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ROLE OF ADRENERGIC NEURONS IN MOTOR CONTROL: EXAMINATION OF CEREBELLAR PURKINJE NEURONS IN MICE FOLLOWING SELECTIVE ADRENERGIC CELL ABLATION IN VIVO
Title
ROLE OF ADRENERGIC NEURONS IN MOTOR CONTROL: EXAMINATION OF CEREBELLAR PURKINJE NEURONS IN MICE FOLLOWING SELECTIVE ADRENERGIC CELL ABLATION IN VIVO.
Creator
Mansour, Monica, Ebert, Steven, University of Central Florida
Abstract / Description
Phenylethanolamine-N-methyltransferase (Pnmt) is the enzyme that catalyzes the conversion of noradrenaline to adrenaline. These catecholamines are synthesized in the medulla of the adrenal gland and by some neurons of the central nervous system. The precise location of Pnmt action in the brain and its physiological significance are unknown. Prior studies led by Aaron Owji, a graduate student in Dr. Ebert�s laboratory, showed that mice with selectively ablated Pnmt cells show signs of...
Show morePhenylethanolamine-N-methyltransferase (Pnmt) is the enzyme that catalyzes the conversion of noradrenaline to adrenaline. These catecholamines are synthesized in the medulla of the adrenal gland and by some neurons of the central nervous system. The precise location of Pnmt action in the brain and its physiological significance are unknown. Prior studies led by Aaron Owji, a graduate student in Dr. Ebert�s laboratory, showed that mice with selectively ablated Pnmt cells show signs of neurological defects such as abnormal gait, weakened grip strength, lack of balance, reduced movement, and defective reflexes during tail suspension tests. The cerebellum is a small section of the brain that is responsible for fine-tuning motor commands. Since the Purkinje cells of the cerebellum act as the sole source of output from the cerebellar cortex, impairment of these cells could possibly account for the motor deficits seen in the mice models. The purpose of this project is to determine if there is indeed a change in Purkinje cells between wild type mice and Pnmt-ablated mice. The first aim is to identify quantitative differences in cell count between both genotypes. The second aim is to determine any morphological changes in the Purkinje cells. The main technique used in this project is immunohistochemistry in which cerebellum tissue from mice models are stained with Calbindin (a cellular marker for Purkinje neurons) and imaged with a confocal microscope. Results showed a slight reduction in the Purkinje cells of the ablated mice compared to the control genotype, accompanied with observable differences in cell structure. Understanding catecholamine pathway mechanisms in the nervous system is imperative for elucidating and targeting key players in neurodegenerative disorders.
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Date Issued
2016
Identifier
CFH2000053, ucf:45511
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFH2000053
CARDIAC CONSEQUENCES OF SELECTIVE ADRENERGIC CELL ABLATION IN MICE
Title
CARDIAC CONSEQUENCES OF SELECTIVE ADRENERGIC CELL ABLATION IN MICE.
Creator
Tumuluri, Lahari, Ebert, Steven, University of Central Florida
Abstract / Description
Phenylethanolamine-N-methyltransferase (Pnmt), is the enzyme that catalyzes the conversion of noradrenaline to adrenaline. It has been found in the embryonic heart and in certain adult heart cells, including intrinsic cardiac adrenergic cells, intracardiac neurons, and cardiomyocytes, but their physiological role in the heart is not well understood. To determine the function of Pnmt-expressing cells in the developing heart, a novel genetically-targeted mouse model that causes selective...
Show morePhenylethanolamine-N-methyltransferase (Pnmt), is the enzyme that catalyzes the conversion of noradrenaline to adrenaline. It has been found in the embryonic heart and in certain adult heart cells, including intrinsic cardiac adrenergic cells, intracardiac neurons, and cardiomyocytes, but their physiological role in the heart is not well understood. To determine the function of Pnmt-expressing cells in the developing heart, a novel genetically-targeted mouse model that causes selective cellular suicide of Pnmt-expressing cells was created by mating Pnmt-Cre Recombinase knock-in mice (Pnmt Cre/Cre) with ROSA26-eGFP-DTA (R26R+/DTA). The �cellular suicide� allele is the Diptheria Toxin A (DTA) gene fragment. Activation of the DTA suicide allele is dependent upon Cre expression, which is under the control of the endogenous Pnmt gene locus (i.e., expression is restricted to adrenaline-producing �adrenergic� cells). Ongoing studies in Dr. Ebert�s laboratory have shown that Pnmt-Cre/DTA mice have a loss of adrenergic cells in the adrenal gland and begin developing serious cardiac and neurological deficits within one month after birth. The purpose of my project is to examine the potential cardiac consequences of selective adrenergic cell ablation in this model. Aim 1 of this study is to analyze echocardiography data from mice with genetic ablation of adrenergic cells compared to age-matched (littermate) controls over the first 6-months after birth. Preliminary evidence indicates that there is substantial loss of function that progressively worsens with age in the ablation group compared to controls. Aim 2 of this study seeks to uncover evidence of adrenergic cell ablation in the heart using histological and immunofluorescence staining techniques. We predict that these experiments will provide physiological and anatomical evidence showing that Pnmt-expressing cells in the heart make significant contributions to cardiac development and function. This knowledge is expected to increase our basic understanding about the specific roles adrenergic cells play during heart, and could lead to the development of novel treatment strategies for certain types of cardiac defects in the future.
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Date Issued
2016
Identifier
CFH2000045, ucf:45512
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFH2000045
ANATOMICAL AND FUNCTIONAL ASSESSMENT OF PNMT+ NEURONS IN THE MOUSE HYPOTHALAMUS AND CEREBELLUM: POTENTIAL ROLES IN ENERGY METABOLISM AND MOTOR CONTROL
Title
ANATOMICAL AND FUNCTIONAL ASSESSMENT OF PNMT+ NEURONS IN THE MOUSE HYPOTHALAMUS AND CEREBELLUM: POTENTIAL ROLES IN ENERGY METABOLISM AND MOTOR CONTROL.
Creator
Lindo, Lake A, Ebert, Steven, University of Central Florida
Abstract / Description
Phenylethanolamine N-methyltransferase (Pnmt) is the enzyme in the catecholamine pathway responsible for converting norepinephrine to epinephrine. Pnmt is present in numerous areas; however, the scope of its expression in the mouse brain is not fully understood. A genetic mouse model was generated by the Ebert lab that exhibited the selective destruction of all Pnmt+ cells through the induction of apoptosis by Diphtheria Toxin A. Unexpected phenotypic defects arose that are characterized by...
Show morePhenylethanolamine N-methyltransferase (Pnmt) is the enzyme in the catecholamine pathway responsible for converting norepinephrine to epinephrine. Pnmt is present in numerous areas; however, the scope of its expression in the mouse brain is not fully understood. A genetic mouse model was generated by the Ebert lab that exhibited the selective destruction of all Pnmt+ cells through the induction of apoptosis by Diphtheria Toxin A. Unexpected phenotypic defects arose that are characterized by metabolic weight deficits and motor ataxia. The distribution of Pnmt+ neurons was examined throughout the hypothalamus and cerebellum to generate an anatomical map of current and historical Pnmt expression using various histochemical methods. Historical Pnmt expression appears more extensive than current expression levels at the adult stage, indicating that certain cells in the mouse brain may have experienced transient Pnmt expression. The presence of Pnmt in these regions suggests that the destruction of these neurons may play a role in the phenotypic defects observed in the ablation mouse model. Gaining a more comprehensive understanding of the potential role of Pnmt in these areas may elucidate new drug targets or novel methods to treat obesity and motor control disorders such as ataxia.
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Date Issued
2018
Identifier
CFH2000547, ucf:45689
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFH2000547
CROSS-TALK OF RETINOIC ACID AND ADRENERGIC HORMONE SIGNALING MAY INFLUENCE DEVELOPMENT OF CARDIAC CONDUCTION AND RHYTHMICITY IN UTERO
Title
CROSS-TALK OF RETINOIC ACID AND ADRENERGIC HORMONE SIGNALING MAY INFLUENCE DEVELOPMENT OF CARDIAC CONDUCTION AND RHYTHMICITY IN UTERO.
Creator
Alam, Sabikha, Ebert, Steven, University of Central Florida
Abstract / Description
Stress hormones, adrenaline and noradrenaline, have been shown to be critical for heart development. Mice lacking dopamine beta-hydroxylase (Dbh), an enzyme responsible for synthesis of these adrenergic hormones, die during mid-gestation due to cardiac failure. Prior research showed that adrenergic cells are found within the electrical conduction system of the heart, and adrenergic deficiency leads to slowed cardiac conduction during embryogenesis. Microarray analysis of wild-type (Dbh+/+)...
Show moreStress hormones, adrenaline and noradrenaline, have been shown to be critical for heart development. Mice lacking dopamine beta-hydroxylase (Dbh), an enzyme responsible for synthesis of these adrenergic hormones, die during mid-gestation due to cardiac failure. Prior research showed that adrenergic cells are found within the electrical conduction system of the heart, and adrenergic deficiency leads to slowed cardiac conduction during embryogenesis. Microarray analysis of wild-type (Dbh+/+) and knockout (Dbh-/-) mouse hearts revealed significant differences in expression of retinoic acid (RA) signaling genes. RA signaling has also been shown to be critical for heart development. These data suggest that heart failure due to adrenergic deficiency may be dependent upon RA signaling. This led to the hypothesis that adrenergic hormones promote the development of the electrical conduction system through modulation of RA signaling. To test this, embryonic mouse hearts were cultured with LE 135, a RA receptor blocker. Heart rate, arrhythmic index (AI) and conduction time were measured. Under these conditions there was a marked increase in arrhythmias. Hearts treated with LE 135 showed a mean AI of 0.232+/-0.057 after 24 hours of treatment while when untreated had an AI of 0.083+/-0.028 (p<0.05;n=15). In contrast, there was no significant change in heart rate or conduction speed after 24 hours with or without the retinoic acid receptor blocker. To determine if adrenergic stimulus influences retinoic acid response, an established RA-sensitive reporter cell line was employed. These F9-RARE-LacZ cells were treated with forskolin (cAMP regulator) and isoproterenol (beta-agonist) to measure changes in RA signaling. Evaluation of RA signaling showed an increase in retinoic acid responsiveness when treated with an adrenergic signaling agonist. These results suggest that proper retinoic acid signaling is essential for maintaining cardiac rhythmicity during embryonic development and adrenergic stimulation can influence this response.
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Date Issued
2011
Identifier
CFH0003831, ucf:44726
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFH0003831
GENETIC AND PHYSIOLOGICAL CONTRIBUTION OF ADRENERGIC CELLS IN HEART DEVELOPMENT
Title
GENETIC AND PHYSIOLOGICAL CONTRIBUTION OF ADRENERGIC CELLS IN HEART DEVELOPMENT.
Creator
Osuala, Kingsley, Ebert, Steven, University of Central Florida
Abstract / Description
The adrenergic hormones norepinephrine (NE) and epinephrine (EPI) are essential for cardiovascular development as embryos lacking NE/EPI begin to die abruptly between embryonic days 10.5 and 11.5 due to apparent cardiac failure. The objective of this research aimed to elucidate the mechanism of embryonic fatality observed in the NE/EPI deficient mouse model. We utilized the dopamine [two]-hydroxylase knockout (Dbh-/-) mouse model, which lacks the gene and subsequent enzyme necessary for...
Show moreThe adrenergic hormones norepinephrine (NE) and epinephrine (EPI) are essential for cardiovascular development as embryos lacking NE/EPI begin to die abruptly between embryonic days 10.5 and 11.5 due to apparent cardiac failure. The objective of this research aimed to elucidate the mechanism of embryonic fatality observed in the NE/EPI deficient mouse model. We utilized the dopamine [two]-hydroxylase knockout (Dbh-/-) mouse model, which lacks the gene and subsequent enzyme necessary for conversion of dopamine to NE. We utilized embryonic mouse hearts at E10.5 from Dbh+/+ (control) and Dbh-/- (experimental model) mice for mRNA transcript expression profiling. Gene expression data suggests a novel connection between the ability of the heart to synthesize adrenergic hormones and the gene expression of enzymes involved in the production of retinoic acid. We found a statistically significant change in transcriptional expression of the retinol binding protein-1 (Rbp-1) [+ 1.4 fold], retinol dehydrogenase 12 (Rdh-12) [+ 2.1 fold], and the beta carotene monooxygenase-1(Bcmo1) [- 2.7 fold] genes in the hearts of E10.5 Dbh-/- embryos. These genes encode enzymes responsible for the transport and enzymatic conversion of retinoic acid precursor molecules. Since alterations in retinoic acid concentration have been shown to cause mid-gestational embryonic teratogenesis and lethality, we chose to quantify retinoic acid present in the Dbh-/-embryo at E10.5. Our results showed a significantly higher concentration of retinoic acid in E10.5 Dbh-/- embryos as compared to wild-type controls. This finding indicates that altered expression of genes involved in retinoic acid synthesis lead to a physiological change in retinoic acid concentration which may contribute to the mid-gestational lethality of the Dbh-/- embryos. Previous studies have shown that adrenergic hormones are produced within the heart itself beginning early in embryonic development, but little is known about the fate and disposition of adrenergic cells within the heart at later stages and into adulthood. To investigate this, we utilized a genetic mouse model that expresses [two]-galactosidase ([two]-Gal) in cells capable of synthesizing EPI in order to identify the spatial and temporal distribution of adrenergic-derived cells in the developing heart. The model was designed so that cells capable of expressing the gene phenylethanolamine N-methyltransferase (Pnmt), which is responsible for the synthesis of epinephrine, also produce the enzyme [two]-Gal as a reporter. Evaluation of the location of these cells in the embryonic heart showed a preferential distribution at the sinoatrial node and atrioventricular sulcus at E10.5, and later at E18.5 a more widely distributed ventricular pattern was observed. In the adult heart, the right myocardium showed two small cclusters of XGAL positive cells, one near the apex and another region of the sinoatrial node. However the left heart myocardium showed XGAL positive cells throughout the left atrium and scattered through the LV where the staining appeared localized to myocytes. Interestingly, the left-sided distribution in the LV appeared to be non-random and non-uniform, since specific regions near the base, mid-section, and apex were consistently XGAL-positive. These findings suggest that adrenergic cells differentiate into cardiac muscle tissue that is predominantly found on the left side of the heart by adult stages of development. Taken collectively, this study has shown a novel connection between adrenergic hormones and RA synthesis, two crucial developmental signaling pathways in the embryonic heart. Remarkably, adrenergic derived cells were also found to persist in the adult heart where they constitute relatively large sections of the left ventricle and atrium. These findings provide important new insights into the mechanism of adrenergic actions in the developing heart and a previously unanticipated structural role for cells descending from an adrenergic lineage in the formation of left myocardial tissue.
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Date Issued
2011
Identifier
CFE0003987, ucf:48653
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0003987
Characterization of neural cells derived from reelin-deficient schizophrenic patient iPS cells
Title
Characterization of neural cells derived from reelin-deficient schizophrenic patient iPS cells.
Creator
Roberts, Nicole, Sugaya, Kiminobu, Ebert, Steven, Masternak, Michal, University of Central Florida
Abstract / Description
Reelin is a large, extracellular glycoprotein that binds to several membrane receptors on neural stem cells (HNSCs), neural progenitor cells (NPCs), and neuroblasts of mammals to direct their migration. Previously, our lab established the presence of Reelin increased migration of wild-type fetal-derived HNSC's, both in vitro and in vivo. In addition, we demonstrated that Reelin protein treatment also increases the formation of radial glia via Notch-1 signaling, in vitro. Radial glia are...
Show moreReelin is a large, extracellular glycoprotein that binds to several membrane receptors on neural stem cells (HNSCs), neural progenitor cells (NPCs), and neuroblasts of mammals to direct their migration. Previously, our lab established the presence of Reelin increased migration of wild-type fetal-derived HNSC's, both in vitro and in vivo. In addition, we demonstrated that Reelin protein treatment also increases the formation of radial glia via Notch-1 signaling, in vitro. Radial glia are precursors to NPCs, as well as a scaffold for neuroblast migration during cortical lamination. Reelin has long been associated with Schizophrenia (SZ). Because post-mortem brains are limited to describing the end-point of the disease, heterozygous haplodeficient Reelin knock-out (Reeler) mice are used to model developmental aspects of SZ in vivo. However, SZ is a complex, polyfactoral disease with a myriad of dysfunctional pathways that may have unforeseen effects on Reelin signaling. K. Brennand et al. (2014) reported low Reelin mRNA expression and cellular characteristics mirroring the Reeler mouse in induced pluripotent stem (iPS) cell-derived NPCs and neurons from living SZ patients. Building upon this and our work with stem cells, here we consider Reelin's effects on migration of Reelin-deficient iPS cell-derived NPCs. Reelin treatment of consists of secreted Reelin from transfected human embryonic kidney 293 cells (HEK 293) with the pCRL RELN gene-containing plasmid created by G. D'Arcangelo (1997) and given to us by T. Curran. Using the metric of cellular migration, this is the first time it have been shown that SZ iNPCs are capable of receiving and reacting to extracellular Reelin. Due to our validation of this model, further work using iPS cell-derived neural cells can confidently be used for future disease modeling and drug discovery of Reelin-deficient SZ.
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Date Issued
2018
Identifier
CFE0007361, ucf:52091
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007361
Unraveling the role of Phenylethanolamine N-methyltransferase (Pnmt+) cells in-vivo
Title
Unraveling the role of Phenylethanolamine N-methyltransferase (Pnmt+) cells in-vivo.
Creator
Manja, Sanjana, Ebert, Steven, Kim, Yoon-Seong, Lambert, Stephen, University of Central Florida
Abstract / Description
Phenylethanolamine N-methyltransferase (Pnmt) is the enzyme that N-methylates norepinephrine to produce the stress hormone/neurotransmitter, epinephrine, which is abundantly expressed in adrenal glands. Developmental studies have also identified Pnmt expression in the embryonic heart and several areas of the brain, including brainstem, cerebellum, and hypothalamus. Thus, we hypothesize that selective ablation of Pnmt+ cells will have detrimental effects on cardiovascular, neuromuscular, and...
Show morePhenylethanolamine N-methyltransferase (Pnmt) is the enzyme that N-methylates norepinephrine to produce the stress hormone/neurotransmitter, epinephrine, which is abundantly expressed in adrenal glands. Developmental studies have also identified Pnmt expression in the embryonic heart and several areas of the brain, including brainstem, cerebellum, and hypothalamus. Thus, we hypothesize that selective ablation of Pnmt+ cells will have detrimental effects on cardiovascular, neuromuscular, and metabolic processes. To uncover the importance of Pnmt+ cells in vivo, we generated a novel Diphtheria Toxin A (DTA) suicide model (Pnmt+/Cre; R26+/DTA) to selectively ablate Pnmt-expressing (Pnmt+) cells in mice. Appearing normal at birth, Pnmt-Cre/DTA mice began to develop apparent cardiovascular, neurological, and metabolic impairments soon thereafter. To measure cardiac function, we performed quantitative echocardiography, electrocardiography (ECG), and blood pressure measurements. Key findings from these assessments indicated decreased left-ventricular performance, slowed atrioventricular conduction, and increased pulse pressure in the Pnmt-Cre/DTA ablation mice. These mice also showed signs of motor control deficits as early as one month, which progressively worsened with age. To assess these effects, we performed standard motor tests including hind-limb clasping, grip strength, and rotarod balance tests. Moreover, we found that the Pnmt-Cre/DTA mice ceased to gain weight shortly after puberty. The motor and metabolic deficits apparent in these animals suggested potential neurological impairments, and we thus undertook immunohistochemical staining experiments to determine the localization of Pnmt+ cells in the brain. Staining revealed Pnmt expression in the Purkinje cells of the cerebellum (motor), paraventricular nucleus of the hypothalamus (metabolic), and surprisingly extensive staining in the cerebral cortex. These results demonstrate that Pnmt+ cell contributions in the brain are much more extensive than previously thought. Overall, this work opens new pathways that will have substantial impacts on our understanding of the roles Pnmt+ cells play in normal development and disorders affecting cardiovascular, motor, and metabolic functions.
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Date Issued
2019
Identifier
CFE0007495, ucf:52649
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007495
Deciphering the Role of Adrenergic Hormones in Embryonic Cardiac Calcium Signaling and Metabolism
Title
Deciphering the Role of Adrenergic Hormones in Embryonic Cardiac Calcium Signaling and Metabolism.
Creator
Peoples, Jessica, Ebert, Steven, Davidson, Victor, Phanstiel, Otto, Yooseph, Shibu, University of Central Florida
Abstract / Description
The adrenergic hormones norepinephrine (NE) and epinephrine (EPI) are critical regulators of mammalian cardiovascular physiology. NE and EPI mediate stress responses to enhance cardiovascular function, however dysregulation of adrenergic signaling leads to heart failure, congenital heart malformations, and sudden cardiac death. Adrenergic hormone-expressing cells were found in the early embryonic heart, and NE has been determined essential for embryonic cardiac development. Despite extensive...
Show moreThe adrenergic hormones norepinephrine (NE) and epinephrine (EPI) are critical regulators of mammalian cardiovascular physiology. NE and EPI mediate stress responses to enhance cardiovascular function, however dysregulation of adrenergic signaling leads to heart failure, congenital heart malformations, and sudden cardiac death. Adrenergic hormone-expressing cells were found in the early embryonic heart, and NE has been determined essential for embryonic cardiac development. Despite extensive work in adults, the regulatory roles and adrenergic targets of these hormones during embryonic cardiac development have not yet been fully determined. Prior transcriptomic studies from our lab showed that expression of signal transduction and metabolic genes in embryos lacking adrenergic hormones were by far the most affected categories of genes. Thus, we hypothesized that adrenergic hormones stimulate early calcium signaling, and are required for sufficient supply of energy substrates for the metabolic shift from anaerobic glycolysis to aerobic respiration during heart development. We utilized the dopamine ?-hydroxylase knock-out (Dbh-/-) mouse model to examine effects of adrenergic-deficiency on calcium signaling and metabolism during heart development. Using calcium-imaging and patch-clamp techniques, we found that calcium transients, voltage-gated calcium channels, and L-type calcium currents in adrenergic-deficient embryonic hearts were not affected relative to controls indicating adrenergic stimulation did not influence early calcium signaling. Metabolomics analyses of adrenergic-deficient hearts revealed disruption in glycolytic and pentose-phosphate pathways as well as reduced activity of respective regulatory enzymes, glyceraldehyde 3-phosphate dehydrogenase and glucose 6-phosphate dehydrogenase indicating compromised glucose metabolism. Addition of pyruvate to embryonic hearts led to significant recovery of ATP concentrations and oxygen consumption rates, thereby supporting the hypothesis that adrenergic-deficient hearts are (")starved(") of metabolic substrates required for transitions from anaerobic glycolysis to aerobic metabolism. Overall, we showed that adrenergic hormones are not necessary for calcium signaling in the embryonic heart, but are essential regulators ensuring sufficient metabolic substrate and boosting enzymatic activities to fuel aerobic metabolism.
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Date Issued
2018
Identifier
CFE0007233, ucf:52223
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007233
Mechanisms of Alpha-Synuclein-Induced Neurodegenertaion in Parkinson's Disease and Stroke
Title
Mechanisms of Alpha-Synuclein-Induced Neurodegenertaion in Parkinson's Disease and Stroke.
Creator
Belal, Cherine, Chan, Sic, Ebert, Steven, Self, William, Teter, Kenneth, University of Central Florida
Abstract / Description
Parkinson's disease (PD) is a debilitating neurodegenerative disorder affecting one million Americans. Despite its social and economic impact, the pathological cascades that lead to neuron dysfunction and degeneration in PD are poorly understood. Endoplasmic reticulum (ER) stress has been implicated as an initiator or contributing factor in neurodegenerative diseases including PD. The ER is an organelle central to protein folding and intracellular Ca2+ homeostasis. Perturbations of these...
Show moreParkinson's disease (PD) is a debilitating neurodegenerative disorder affecting one million Americans. Despite its social and economic impact, the pathological cascades that lead to neuron dysfunction and degeneration in PD are poorly understood. Endoplasmic reticulum (ER) stress has been implicated as an initiator or contributing factor in neurodegenerative diseases including PD. The ER is an organelle central to protein folding and intracellular Ca2+ homeostasis. Perturbations of these functions result in ER stress and upregulation of ER stress proteins, of which some have been implicated in counteracting ER stress-induced cell death. The mechanisms that lead to ER stress and how ER stress proteins contribute to the degenerative cascades remain unclear but their understanding is critical to devising effective therapies for PD. Both the accumulation of mutant a-synuclein (aSyn), which causes an inherited form of PD, and the inhibition of mitochondrial complex I function by PD-inducing neurotoxin lead to ER stress. The critical involvement of ER stress in experimental models of PD supports its potential relevance to PD pathogenesis and led us to test the hypothesis whether the homocysteine-inducible ER protein (Herp), an ubiquitin-like domain (UBD) containing ER-resident protein, can counteract mutant Alpha Syn- and neurotoxin- induced pathological cascades.
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Date Issued
2011
Identifier
CFE0004470, ucf:49310
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0004470
Dissertation Title: Development of molecular and cellular imaging tools to evaluate gene and cell based therapeutic strategies in vivo
Title
Dissertation Title: Development of molecular and cellular imaging tools to evaluate gene and cell based therapeutic strategies in vivo.
Creator
Xia, Jixiang, Ebert, Steven, Khaled, Annette, Cheng, Zixi, Daniell, Henry, University of Central Florida
Abstract / Description
Molecular imaging modalities are important tools to evaluate the efficacy of gene delivery systems and cell-based therapies. Development and application of these modalities will advance our understanding of the mechanism of transgene expression and cell fate and functions. Physical gene transfer methods hold many advantages over viral vectors among gene therapeutic strategies. Here, we evaluated the efficacy of biolistic ((")gene gun(")) gene targeting to tissues with non-invasive...
Show moreMolecular imaging modalities are important tools to evaluate the efficacy of gene delivery systems and cell-based therapies. Development and application of these modalities will advance our understanding of the mechanism of transgene expression and cell fate and functions. Physical gene transfer methods hold many advantages over viral vectors among gene therapeutic strategies. Here, we evaluated the efficacy of biolistic ((")gene gun(")) gene targeting to tissues with non-invasive bioluminescence imaging (BLI) methods. Plasmids carrying the firefly luciferase reporter gene were transfected into mouse skin and liver using biolistics, and BLI was measured at various time points after transfer. With optimized DNA loading ratio (DLRs), reporter gene expression reached to peak 1day after transfer to mouse skin, and the maximum depth of tissue penetration was between 200-300?m. Similar peak expression of reporter gene was found in mouse liver but the expression was relatively stable 4-8 days post-biolistic gene transfer and remained for up to two weeks afterward. Our results demonstrated BLI was an efficient strategy for evaluation of reporter gene expression in the same animals over a period of up to two weeks in vivo. Different tissues showed different expression kinetics, suggesting that this is an important parameter to consider when developing gene therapy strategies for different target tissues. We also employed BLI to measure differentiation of mouse embryonic stem (ES) cells into beating cardiomyocytes in vitro and in vivo. A subset of these cardiomyocytes appears to be derived from an adrenergic lineage that ultimately contribute to substantial numbers of cardiomyocytes primarily on the left side of the heart. At present, it is unclear what the precise role of these cardiac adrenergic cells is with respect to heart development, though it is known that adrenergic hormones (adrenaline and noradrenaline) are essential for embryonic development since mice lacking them die from apparent heart failure during the prenatal period. To identify and characterize cardiac adrenergic cells, we developed a novel mouse genetic model in which the nuclear-localized enhanced green fluorescent protein (nEGFP) reporter gene was targeted to the first exon of the Phenylethanoamine N-transferase (Pnmt) gene, which encodes for the enzyme that converts noradrenaline to adrenaline, and hence serves as a marker for adrenergic cells. Our results demonstrate this knock-in strategy effectively marked adrenergic cells in both fetal and adult mice. Expression of nEGFP was found in Pnmt-positive cells of the adult adrenal medulla, as expected. Pnmt-nEGFP expression also recapitulated endogenous Pnmt expression in the embryonic mouse heart. In addition, nEGFP and Pnmt expression were induced in parallel during differentiation of pluripotent mouse ES cells into beating cardiomyocytes. This new mouse genetic model provides a useful new tool for studying the properties of adrenergic cells in different tissues. We also identified two limitations of the Pnmt-nEGFP model. One is that the amount of nEGFP expressed within individual adrenergic cells was highly variable. Secondly, expression of nEGFP in the embryonic heart was of low abundance and difficult to distinguish from background autofluorescence. To overcome these limitations, we developed two alternative genetic models to investigate adrenergic cells: (1) Mouse embryonic stem cells, which have been previously targeted with Pnmt-Cre recombinase gene, were additionally targeted with a dual reporter plasmid which covered both a loxP-flanked cDNA of red fluorescence protein (HcRed) and also EGFP. Under the undifferentiated status, cells emit red fluorescence as transcription stops before EGFP coding sequence. After differentiation into beating cardiomyoctyes, some cells switch fluorescence from red to green, indicating that excision of loxP-flanked sequences by Cre since Pnmt had been activated. (2) A surface marker, truncated low-affinity nerve growth factor receptor (?LNGFR) was used as the reporter gene as cells expressing this marker can be enriched by magnetic-activated cell sorting (MACS), a potentially efficient way to yield highly purified positive cells at low input abundance in a population. Through a series of subcloning steps, the targeting construct, Pnmt-?LNGFR-Neo-DTA was created and electroporated into 7AC5EYFP embryonic stem cells. Correctly targeted cells were selected by positive and negative screening. These cells provide a new tool with which to identify, isolate, and characterize the function of adrenergic cells in the developing heart, adrenal gland, and other tissues where adrenergic cells make important contributions.
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Date Issued
2011
Identifier
CFE0004491, ucf:49287
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0004491
Genetically-programmed suicide of adrenergic cells in the mouse leads to severe left ventricular dysfunction, impaired weight gain, and symptoms of neurological dysfunction
Title
Genetically-programmed suicide of adrenergic cells in the mouse leads to severe left ventricular dysfunction, impaired weight gain, and symptoms of neurological dysfunction.
Creator
Owji, Aaron, Ebert, Steven, King, Stephen, Sugaya, Kiminobu, University of Central Florida
Abstract / Description
Phenylethanolamine-N-methyltransferase (Pnmt) catalyzes the conversion of noradrenaline to adrenaline and is the last enzyme in the catecholamine biosynthetic pathway. Pnmt serves as a marker for adrenergic cells, and lineage-tracing experiments have identified the embryonic heart and hindbrain region as the first sites of Pnmt expression in the mouse. Pnmt expression in the heart occurs before the adrenal glands have formed and prior to sympathetic innervation, suggesting that the heart is...
Show morePhenylethanolamine-N-methyltransferase (Pnmt) catalyzes the conversion of noradrenaline to adrenaline and is the last enzyme in the catecholamine biosynthetic pathway. Pnmt serves as a marker for adrenergic cells, and lineage-tracing experiments have identified the embryonic heart and hindbrain region as the first sites of Pnmt expression in the mouse. Pnmt expression in the heart occurs before the adrenal glands have formed and prior to sympathetic innervation, suggesting that the heart is the first site of catecholamine production in the mouse. The function of these Pnmt+ cells in heart development remains unclear. In the present study, we test the hypothesis that (i) a genetic ablation technique utilizing a suicide reporter gene selectively destroys Pnmt cells in the mouse, and (ii) Pnmt cells are required for normal cardiovascular and neurological function.To genetically ablate adrenergic cells, we mated Pnmt-Cre mice, in which Cre-recombinase is under the transcriptional regulation of the Pnmt promoter, and a Cre -activated diphtheria toxin A (DTA) mouse strain (ROSA26-eGFP-DTA), thereby causing activation of the toxic allele (DTA) in Pnmt-expressing (adrenergic) cells resulting in selective (")suicide(") of these cells in approximately half of the offspring. The other half serve as controls because they do not have the ROSA26-eGFP-DTA construct. In the Pnmt+/Cre; R26+/DTA offspring, we achieve a dramatic reduction in Pnmt transcript and Pnmt immunoreactive area in the adrenal glands. Furthermore, we show that loss of Pnmt cells results in severe left ventricular dysfunction that progressively worsens with age. These mice exhibit severely reduced cardiac output and ejection fraction due to decreased LV contractility and bradycardia at rest. Surprisingly, these mice appear to have a normal stress response, as heart rate and ejection fraction increased to a similarextent compared to controls. In addition to baseline cardiac dysfunction, these mice fail to gain body weight in a normal manner and display gross neurological dysfunction, including muscular weakness, abnormal gaiting, and altered tail suspension reflex, an indicator of neurological function.This work demonstrates that selective Pnmt cell destruction leads to severe left ventricular dysfunction, lack of weight gain, and neurological dysfunction. This novel mouse is expected to shed insight into the role of Pnmt cells in the heart, and suggests a role for Pnmt cells in neurological regulation of feeding behavior, metabolism, and motor control.
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Date Issued
2015
Identifier
CFE0006048, ucf:50984
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006048
Molecular Mechanisms involved in inflammatory angiogenesis induced by monocyte chemotactic protein induced protein-1 (MCPIP1)
Title
Molecular Mechanisms involved in inflammatory angiogenesis induced by monocyte chemotactic protein induced protein-1 (MCPIP1).
Creator
Roy, Arpita, Kolattukudy, Pappachan, Ebert, Steven, Parthasarathy, Sampath, Self, William, University of Central Florida
Abstract / Description
Major diseases such as cardiovascular diseases, diabetes, obesity and tumor growth are known to involve inflammatory angiogenesis. MCP-induced protein 1 (MCPIP1) encoded by ZC3H12A gene, was reported to promote angiogenesis and is addressed in my dissertation as MCPIP. The mechanism/s involved in the angiogenic differentiation induced by MCPIP was however unknown. The aim of this study was to bridge this gap in our knowledge and delineate the molecular mechanisms and sequential processes...
Show moreMajor diseases such as cardiovascular diseases, diabetes, obesity and tumor growth are known to involve inflammatory angiogenesis. MCP-induced protein 1 (MCPIP1) encoded by ZC3H12A gene, was reported to promote angiogenesis and is addressed in my dissertation as MCPIP. The mechanism/s involved in the angiogenic differentiation induced by MCPIP was however unknown. The aim of this study was to bridge this gap in our knowledge and delineate the molecular mechanisms and sequential processes involved in angiogenesis mediated via MCPIP. To determine if angiogenesis induced by inflammatory cytokines, TNF-?, IL-1? and IL-8 is mediated via induction of MCPIP, knockdown of MCPIP by its specific siRNA, in human umbilical vein endothelial cells was performed. Oxidative stress, ER stress and autophagy are known to be involved in mediating inflammation. We hypothesized that MCPIP-induced angiogenic differentiation is mediated via induction of oxidative stress, ER stress and autophagy. Chemical inhibitors and specific gene knockdown approach were used to inhibit each process postulated. Oxidative stress was inhibited by apocynin or cerium oxide nanoparticles or knockdown of NADPH oxidase subunit, phox47. Endoplasmic reticulum (ER) stress was blocked by tauroursodeoxycholate or knockdown of ER stress signaling protein IRE-1 and autophagy was inhibited by the use of 3?methyl adenine, or LY 294002 or by specific knockdown of beclin1. Matrigel assay was used as an in vitro tool to assay angiogenic differentiation. Inhibition of each step inhibited the subsequent steps postulated. The results reveal that angiogenesis induced by inflammatory agents is mediated via sequential induction of MCPIP that causes oxidative and nitrosative stress resulting in ER stress leading to autophagy required for angiogenesis. MCPIP has deubiquitinase and anti-dicer RNase activities. If and how the dual enzymatic activities of MCPIP mediate angiogenesis was unknown. Our results showed that hypoxia-induced angiogenesis is mediated via MCPIP. MCPIP deubiquitinated ubiquitinated hypoxia-inducible factor (HIF-1?) and the stabilized HIF-1? entered the nucleus to promote the transcription of its target genes, cyclooxygenase-2 and vascular endothelial growth factor causing the activation of p38 MAP kinase involved in angiogenesis. MCPIP expression promoted angiogenesis by inhibition of thrombospondin-1 synthesis via induction of silent information regulator (SIRT)-1 and/or via suppression of VEG-inhibitor levels caused by inhibition of NF-?B activation. MCPIP inhibited the production of the anti-angiogenic microRNAs (miR)-20b and miR-34a that repress the translation of HIF-1? and SIRT-1, respectively. Cells expressing the RNase-dead mutant of MCPIP, D141N, that had lost the ability to induce angiogenesis had deubiquitinase activity but did not inhibit the production of miR-20b and miR-34a. Mimetics of miR-20b and miR-34a inhibited MCPIP-induced angiogenesis. These results show for the first time that both deubiquitinase and anti-dicer RNase activities of MCPIP are involved in inflammatory angiogenesis. Results from our study delineate key processes that could be potential targets for therapeutic intervention against inflammatory angiogenesis.
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Date Issued
2012
Identifier
CFE0004793, ucf:49760
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0004793
Establishment of Methods for Isolation of Pnmt+ Cardiac Progenitor Cells
Title
Establishment of Methods for Isolation of Pnmt+ Cardiac Progenitor Cells.
Creator
Varudkar, Namita, Ebert, Steven, Parthasarathy, Sampath, Muller, Mark, University of Central Florida
Abstract / Description
Cardiovascular disease is the leading cause of death in the United States. Millions of patients suffer each year from endothelial dysfunction and/or debilitating myocardial damage resulting in decreased quality of life and increased risk of death or disablement. Current pharmacological approaches are only partly effective at treating cardiovascular disease, and hence, better strategies are needed to provide significant improvements in treatment options. Cardiac stem/progenitorcells have the...
Show moreCardiovascular disease is the leading cause of death in the United States. Millions of patients suffer each year from endothelial dysfunction and/or debilitating myocardial damage resulting in decreased quality of life and increased risk of death or disablement. Current pharmacological approaches are only partly effective at treating cardiovascular disease, and hence, better strategies are needed to provide significant improvements in treatment options. Cardiac stem/progenitorcells have the potential to regenerate myocardial tissue and repair damaged heart muscle. There are many different types of cardiac progenitor cells, and each may have certain unique properties and characteristics that would likely be useful for particular clinical applications. A current challengein the field is to identify, isolate, and test specific cardiac stem/progenitor cell populations for their ability to repair/regenerate myocardial tissue. Our laboratory has discovered a new type of cardiac progenitor cell that expresses the enzyme, Phenylethanolamine-n-methyltransferase (Pnmt). My initial studies focused on identification of Pnmt+ cells based on knock-in of a nuclear-localized Enhanced Green Fluorescent Protein (nEGFP) reporter gene into exon 1 of the Pnmt gene in a stable recombinant Pnmt-nEGFP mouse embryonic stem cell (mESC) line. These cells were differentiated into cardiomyocytes, and I identified nEGFP+ cells using fluorescence, immunofluorescence, and phase-contrast microscopy techniques. Our results showed that only about 0.025% ( 1 per 4000) of the cardiac-differentiating stem cells expressed the nEGFP+ marker. Because of the relative rarity of these cells, optimization of isolation methods proved initially challenging. To overcome this technical barrier, I used a surrogate cell culture system to establish the methodsof isolation based on expression of either a fluorescent cell marker (EGFP), or a unique cell surface receptor represented by an inactivated (truncated) version of the human low-affinity nerve growth factor receptor (LNGFR). Plasmid DNA containing these reporter genes was transiently transfected into a permissive cell line (RS1), and reporter gene expression was used to identify and isolate transfected from non-transfected cells using either Fluorescence-Activated Cell Sorting(FACS) or Magnetic-Activated Cell Sorting (MACS) methods. The main objective of the study was to establish the isolation techniques based on the expression of reporter genes (EGFP and LNGFR) in RS1 cells. Following transfection, EGFP+ cells were successfully isolated via FACS as verified by flow cytometric and microscopic analyses, which showed that approximately 96% of the isolated cells were indeed EGFP+. Despite the relative purity of the isolated cell population, however, their viability in culture following FACS was substantially compromised ( 50% attrition). In contrast, MACS enabled efficient isolation of LNGFR+ cells, and the vast majority of these ( 90%) retained viability in culture following MACS. The LNGFR expression was verified using RT-PCR. Further, MACS methods enabled isolation of marked cells in about 5-7 mins, whereas it took 2-4 hours to using FACS to perform similar isolations from the same amount of starting material (10^6 cells). In addition, MACS is a more economical method in that it does not require the use of an expensive laser-based instrument to perform the sorting. These results suggest that MACS was a more efficient, gentle, and feasible technique than FACS for isolation of reporter-tagged mammalian cells. Consequently, future studies aimed at isolation of Pnmt+ cardiac progenitor cells will thus primarily focus on MACS methods.
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Date Issued
2014
Identifier
CFE0005558, ucf:50287
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005558
A Complete Approach to Predict Biodistribution of Nanomaterials Within Animal Species from In-vitro Data
Title
A Complete Approach to Predict Biodistribution of Nanomaterials Within Animal Species from In-vitro Data.
Creator
Price, Edward, Gesquiere, Andre, Huo, Qun, Kolpashchikov, Dmitry, Rex, Matthew, Ebert, Steven, University of Central Florida
Abstract / Description
Smart drug-design for antibody and nanomaterial-based therapies allows for optimization of drug efficacy and more efficient early-stage pre-clinical trials. The ideal drug must display maximum efficacy at target tissue sites, but to track and predict distribution to these sites, one must have a mechanistic understanding of the kinetics involved with the individual cells of the tissue itself. This process can be tracked through biological simulations coupled with in-vitro approaches, which...
Show moreSmart drug-design for antibody and nanomaterial-based therapies allows for optimization of drug efficacy and more efficient early-stage pre-clinical trials. The ideal drug must display maximum efficacy at target tissue sites, but to track and predict distribution to these sites, one must have a mechanistic understanding of the kinetics involved with the individual cells of the tissue itself. This process can be tracked through biological simulations coupled with in-vitro approaches, which result in a rapid and efficient in-depth understanding of drug transport within tissue vasculature and cellular environment. As a result, it becomes possible to predict drug biodistribution within live animal tissue cells without the need for animal studies. Herein, we use in-vitro assays to translate transport kinetics to whole-body animal simulations to predict drug distribution from vasculature into individual tissue cells for the first time. Our approach is based on rate constants obtained from an in-vitro assay that accounts for cell-induced degradation, which are translated to a complete animal simulation to predict nanomedicine biodistribution at the single cell level. This approach delivers predictions for therapies of varying size and type for multiple species of animals solely from in-vitro data. Thus, we expect this work to assist in refining, reducing, and replacing animal testing, while at the same time, giving scientists a new perspective during early stages of drug development.
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Date Issued
2019
Identifier
CFE0007900, ucf:52747
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007900
Dissecting the Components of Neuropathic Pain
Title
Dissecting the Components of Neuropathic Pain.
Creator
George, Dale, Lambert, Stephen, Kim, Yoon-Seong, Fernandez-Valle, Cristina, Ebert, Steven, University of Central Florida
Abstract / Description
Pain is a public health issue affecting the lives of nearly 116 million adults in the US, annually. Understanding the physiological and phenotypic changes that occur in response to painful stimuli is of tremendous clinical interest, but, the complexity of pain and the lack of a representative in vitro model hinders the development of new therapeutics. Pain stimuli are first perceived and transmitted by the neurons within the dorsal root ganglia (DRG) which become hyperexcitable under these...
Show morePain is a public health issue affecting the lives of nearly 116 million adults in the US, annually. Understanding the physiological and phenotypic changes that occur in response to painful stimuli is of tremendous clinical interest, but, the complexity of pain and the lack of a representative in vitro model hinders the development of new therapeutics. Pain stimuli are first perceived and transmitted by the neurons within the dorsal root ganglia (DRG) which become hyperexcitable under these conditions. It has now been established that satellite glial cells (SGCs) that ensheathe the DRG cell body actively contribute to this neuronal dysregulation. To understand the role of SGCs in this pain circuit, first, we looked at the development of SGCs within the DRG of rats, and we showed that SGCs developed postnatally, and appeared morphologically, transcriptionally and functionally similar to Schwann cells precursors (SCs), supporting the idea that these cells may exhibit multipotent behavior. Secondly, we describe here, a three-dimensional in vitro model of the DRG which is functionally characterized on a microelectrode array (MEA). This model can be used to assess the long-term recording of spontaneous activity from bundles of axons while preserving the neuronal-SGC interactions similar to those observed in vivo. Furthermore, using capsaicin, an agonist of the TRPV1 nociceptive receptor, we show that this model can be used as an in vitro assay to acquire evoked responses from nociceptive neurons. Overall, this study advances our knowledge on the development and differentiation of SGCs and establishes a novel functional three-dimensional model for the study of SGCs. This model can now be used as a tool to study the underlying basis of neuronal dysregulation in pain.
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Date Issued
2018
Identifier
CFE0007002, ucf:52053
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007002
Biochemical Studies of ABCE1
Title
Biochemical Studies of ABCE1.
Creator
Sims, Lynn, Igarashi, Robert, Ebert, Steven, Self, William, Moore, Sean, University of Central Florida
Abstract / Description
The growth and survival of all cells require functional ribosomes that are capable of protein synthesis. The disruption of the steps required for the function of ribosomes represents a potential future target for pharmacological anti-cancer therapy. ABCE1 is an essential Fe-S protein involved in ribosomal function and is vital for protein synthesis and cell survival. Thus, ABCE1 is potentially a great therapeutic target for cancer treatment. Previously, cell biological, genetic, and...
Show moreThe growth and survival of all cells require functional ribosomes that are capable of protein synthesis. The disruption of the steps required for the function of ribosomes represents a potential future target for pharmacological anti-cancer therapy. ABCE1 is an essential Fe-S protein involved in ribosomal function and is vital for protein synthesis and cell survival. Thus, ABCE1 is potentially a great therapeutic target for cancer treatment. Previously, cell biological, genetic, and structural studies uncovered the general importance of ABCE1, although the exact function of the Fe-S clusters was previously unclear, only a simple structural role was suggested. Additionally, due to the essential nature of ABCE1, its function in ribosome biogenesis, ribosome recycling, and the presence of Fe-S within ABCE1, the protein has been hypothesized to be a target for oxidative degradation by ROS and critically impact cellular function. In an effort to better understand the function of ABCE1 and its associated Fe-S cofactors, the goal of this research was to achieve a better biochemical understanding of the Fe-S clusters of ABCE1. The kinetics of the ATPase activity for the Pyrococcus abyssi ABCE1 (PabABCE1) was studied using both apo- (without reconstituted Fe-S clusters) and holo- (with full complement of Fe-S clusters reconstituted post-purification) forms, and is shown to be jointly regulated by the status of Fe-S clusters and Mg2+. Typically, ATPases require Mg2+, as is true for PabABCE1, but Mg2+ also acts as a unusual negative allosteric effector that modulates ATP affinity of PabABCE1. Comparative kinetic analysis of Mg2+ inhibition shows differences in the degree of allosteric regulation between the apo- and holo-PabABCE1 where the apparent Km for ATP of apo-PabABCE1 increases (>)30 fold from ~30 (&)#181;M to over 1 mM when in the presence of physiologically relevant concentrations of Mg2+. This effect would significantly convert the ATPase activity of PabABCE1 from being independent of cellular energy charge to being dependent on energy charge with cellular [Mg2+]. The effect of ROS on the Fe-S clusters within ABCE1 from Saccharomyces cerevisiae was studied by in vivo 55Fe labeling. A dose and time dependent depletion of ABCE1 bound 55Fe after exposure to H2O2 was discovered, suggesting the progressive degradation of Fe-S clusters under oxidative stress conditions. Furthermore, our experiments show growth recovery, upon removal of the H2O2, reaching a growth rate close to that of untreated cells after ~8 hrs. Additionally, a corresponding increase (~88% recovery) in the ABCE1 bound 55Fe (Fe-S) was demonstrated. Observations presented in this work demonstrate that the majority of growth inhibition, induced by oxidative stress, can be explained by a comparable decrease in ABCE1 bound 55Fe and likely loss of ABCE1 activity that is necessary for normal ribosomal activity. The regulatory roles of the Fe-S clusters with ABCE1 provide the cell a way to modulate the activity of ABCE1 and effectively regulate translation based on both cellular energy charge and the redox state of the cell. Intricate overlapping effects by both [Mg2+] and the status of Fe-S clusters regulate ABCE1's ATPase activity and suggest a regulatory mechanism, where under oxidative stress conditions, the translational activity of ABCE1 can be inhibited by oxidative degradation of the Fe-S clusters. These findings uncover the regulatory function of the Fe-S clusters with ABCE1, providing important clues needed for the development of pharmacological agents toward ABCE1 targeted anti-cancer therapy.
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Date Issued
2012
Identifier
CFE0004600, ucf:49204
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0004600
The Actin-Severing Protein Cofilin Is Downstream Of Neuregulin Signaling, Is Regulated By The Tumor Suppressor Merlin, And Is Essential For Schwann Cell Myelination
Title
The Actin-Severing Protein Cofilin Is Downstream Of Neuregulin Signaling, Is Regulated By The Tumor Suppressor Merlin, And Is Essential For Schwann Cell Myelination.
Creator
Sparrow, Nicklaus, Fernandez-Valle, Cristina, Lambert, Stephen, Ebert, Steven, Altomare, Deborah, University of Central Florida
Abstract / Description
Myelination is a complex process requiring coordination of directional motility and an increase in Schwann cell (SC) size to generate a multi-lamellar myelin sheath. Regulation of actin dynamics during myelination is poorly understood. However, it is known that myelin thickness is related to the abundance of neuregulin1-type III (NRG) expressed on the axon surface. NRG binding to ErbB2/3 receptors on the Schwann cell surface initiates signaling cascades necessary for myelination. We identify...
Show moreMyelination is a complex process requiring coordination of directional motility and an increase in Schwann cell (SC) size to generate a multi-lamellar myelin sheath. Regulation of actin dynamics during myelination is poorly understood. However, it is known that myelin thickness is related to the abundance of neuregulin1-type III (NRG) expressed on the axon surface. NRG binding to ErbB2/3 receptors on the Schwann cell surface initiates signaling cascades necessary for myelination. We identify cofilin1, an actin depolymerizing and severing protein, as a downstream target of NRG-ErbB2/3 signaling in rat SC. A five minute exposure of SCs to NRG triggers phosphorylation of ErbB2 with concomitant dephosphorylation, and activation, of cofilin, and its upstream regulators, LIM domain kinase (LIMK) and Slingshot-1 phosphatase (SSH). This leads to cofilin activation and recruitment to the leading edge of the SC plasma membrane. These changes are associated with rapid plasma membrane expansion yielding a 35(-)50% increase in SC size within 30 minutes of NRG1 exposure. Cofilin1-deficient SCs increase phosphorylation of ErbB2, ERK, focal adhesion kinase, and paxillin in response to NRG, but fail to increase in size possibly due to stabilization of unusually long focal adhesions. Cofilin1-deficient SCs co-cultured with sensory neurons fail to elaborate myelin. Ultrastructural analysis reveals that they unsuccessfully segregate or engage axons and form only patchy basal lamina. After 48 hours of co-culturing with neurons, cofilin-deficient SCs fail to align and elongate on axons and often adhere to the underlying substrate rather than to axons. We show that the Neurofibromatosis Type II (NF2) tumor suppressor, merlin, is an upstream regulator of cofilin1, and that merlin knockdown in Schwann cells inhibits their elaboration of normal myelin sheaths in vitro. Merlin-deficient SCs form shorter myelin segments in DRG neuron/SC co-cultures. Merlin-deficient Schwann cells have increased levels of both active Rac (Rac-GTP) and F-actin indicative of a stable actin cytoskeleton. Surprisingly merlin-deficient Schwann cells fail to dephosphorylate and activate cofilin1 in response to NRG stimulation. Inhibition of LIMK restores the ability of merlin-deficient SCs to activate cofilin in response to NRG. In developing rat sciatic nerve, merlin becomes hyper-phosphorylated at S518 during the time of peak myelin formation. During this time, cofilin is localized to the inner mesaxon, and subsequently to Schmidt-Lanterman incisures in mature myelin. This study: 1) identifies cofilin and its upstream regulators, LIMK and SSH, as end targets of a NRG-ErbB2/3 signaling pathway in Schwann cells, 2) demonstrates that cofilin modulates actin dynamics in Schwann cells allowing for motility needed to effectively engage and myelinate axons, 3) shows that merlin regulates NRG-ErbB2/3-cofilin-actin signaling during SC myelination to determine the myelin segment length.
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Date Issued
2017
Identifier
CFE0006664, ucf:51217
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006664
Functional Identification of Nucleus Tractus Solitarius (NTS) Barosensitive Neurons: Effect of Chronic Intermittent Hypoxia (CIH)
Title
Functional Identification of Nucleus Tractus Solitarius (NTS) Barosensitive Neurons: Effect of Chronic Intermittent Hypoxia (CIH).
Creator
Kolpakova, Jenya, Cheng, Zixi, Naser, Saleh, Kim, Yoon-Seong, Ebert, Steven, University of Central Florida
Abstract / Description
Chronic Intermittent Hypoxia (CIH) is a model used to study obstructive sleep apnea (OSA). Previously, we showed that baroreflex control of heart rate (HR) (baroreflex sensitivity) is reduced in CIH rats. While afferent function and HR in response to vagal efferent stimulationare enhanced, the effect of CIH on the central components, in particular NTS, is still notcompletely understood. F344 rats (3-4 mo) were exposed either to CIH or room air (RA) for 35-50 days. Following CIH exposure, rats...
Show moreChronic Intermittent Hypoxia (CIH) is a model used to study obstructive sleep apnea (OSA). Previously, we showed that baroreflex control of heart rate (HR) (baroreflex sensitivity) is reduced in CIH rats. While afferent function and HR in response to vagal efferent stimulationare enhanced, the effect of CIH on the central components, in particular NTS, is still notcompletely understood. F344 rats (3-4 mo) were exposed either to CIH or room air (RA) for 35-50 days. Following CIH exposure, rats were anaesthetized with Ket/Ace. Using single-unitextracellular recording technique, we recorded NTS barosensitive neurons in response to arterialpressure (AP) changes induced by descending aorta occlusion. Our data indicated that 1) themean arterial pressure and HR were similar in RA control and CIH groups. 2) The majority ofneurons from RA and CIH NTS neurons increased firing rate, whereas other neurons decreasedfiring upon AP elevation. 3) In 27 RA and 31 CIH NTS neurons with increased firing rate, 15 RA and 15 CIH neurons were activated at a low ?MAP at the early phase of AP increase (early neurons); whereas 12 RA neurons and 16 CIH neurons were activated at a late phase of AP increase (late neurons). The early neurons rapidly increased their firing during the rising phase of MAP, whereas late neurons did not increase their firing until the ?MAP reached its peak. 4) Early neuron activity-?MAP relationship was further characterized by the logistic sigmoid function curve. CIH significantly increased the maximal gain of the neuron activity-?MAP curve and the range of the response. In addition, CIH early neurons had a significantly higher firingrate than RA early neurons, whereas CIH did not change the firing rate in late neurons. 5) Forlate neurons, HR reduction correlated with neuronal activity. HR reduction-neuronal activityincrease curve was shifted to the right in CIH neurons, indicating that CIH decreased HR control in response to NTS firing increase. Collectively, our data suggest that NTS barosensitive neuronshave both early and late neurons, CIH selectively enhances neuron activity in response to APchanges in NTS early neurons and attenuate the baroreflex bradycardia. Along our previous workthat CIH-induced the cell loss in the nucleus ambiguus (NA), we conclude that CIH attenuatesthe functions of NA, whereas enhances the NTS functions to compensate for the loss of functionin NA
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Date Issued
2015
Identifier
CFE0005967, ucf:50806
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005967
A high-content multiplexed screening platform for the evaluation and manipulation of force and fatigue of adult derived skeletal muscle myotubes in defined serum-free medium
Title
A high-content multiplexed screening platform for the evaluation and manipulation of force and fatigue of adult derived skeletal muscle myotubes in defined serum-free medium.
Creator
McAleer, Christopher, Hickman, James, Ebert, Steven, Perez Figueroa, J. Manuel, Lambert, Stephen, University of Central Florida
Abstract / Description
The overall focus of this project has two parts: First, was to develop a protocol utilizing serum-free media formulations and defined plating and culture techniques to create functional in vitro myotubes derived from adult skeletal muscle satellite cells. The second was to manipulate the inherent muscle parameters such as force output and fatigue of these myotubes by employing exercise regimes or by small molecule application. The importance of serum-free medium use for in vitro cultures is...
Show moreThe overall focus of this project has two parts: First, was to develop a protocol utilizing serum-free media formulations and defined plating and culture techniques to create functional in vitro myotubes derived from adult skeletal muscle satellite cells. The second was to manipulate the inherent muscle parameters such as force output and fatigue of these myotubes by employing exercise regimes or by small molecule application. The importance of serum-free medium use for in vitro cultures is becoming increasingly important in creating functional systems that can be validated for drug testing by the Food and Drug Administration (FDA). Also, the study of age related diseases as well as the potential for (")personalized medicine(") relies on the proliferation and maturation of satellite cells from adult derived tissue. For that purpose, a serum-free medium and culture system was designed to create mature striated myotubes in culture on a defined non-biological substrate N-1[3-trimethoxysilyl propyl] diethylenetriamine (DETA). These myotubes were evaluated by morphology, muscle specific protein expression, and by muscle functionality. After the thorough characterization of the resultant myotubes the functional output of the muscle was altered utilizing chemical means (creatine supplementation and PGC-1? agonists), chronic long term stimulation, and the use of PGC-1? deficient tissue. In this thesis presentation the utility of the newly developed medium formulation to create myotubes from a variety of adult derived muscle sources will be shown. A protocol in which to exercise skeletal muscle in vitro to alter endurance was developed and employed to manipulate skeletal muscle. Finally, small molecules were tested to validate this system for drug study use. This engineered system has the potential for high-throughput screening of drugs for efficacy and drug toxicity studies as well as general biological studies on muscle fatigue.
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Date Issued
2015
Identifier
CFE0005660, ucf:50162
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005660
Role of Cardiac Catecholamines in Embryos and Adults Under Stress
Title
Role of Cardiac Catecholamines in Embryos and Adults Under Stress.
Creator
Baker, Candice, Ebert, Steven, Bossy-Wetzel, Ella, Siddiqi, Shadab, Lambert, Stephen, University of Central Florida
Abstract / Description
Cardiovascular disease is responsible for the loss of one life every 38 seconds and accounts for 26.6 percent of all infants that die of congenital birth defects. Adrenergic hormones are critically important regulators of cardiovascular physiology in embryos and adults. They are key mediators of stress responses and have profound stimulatory effects on cardiovascular function, and dysregulation of adrenergic function has been associated with many adverse cardiac conditions, including...
Show moreCardiovascular disease is responsible for the loss of one life every 38 seconds and accounts for 26.6 percent of all infants that die of congenital birth defects. Adrenergic hormones are critically important regulators of cardiovascular physiology in embryos and adults. They are key mediators of stress responses and have profound stimulatory effects on cardiovascular function, and dysregulation of adrenergic function has been associated with many adverse cardiac conditions, including congenital malformations, arrhythmias, ischemic heart disease, heart failure, and sudden cardiac death. Despite intensive study, the specific roles these hormones play in the developing heart is not well-understood. Further, there is little information available regarding how these important hormones mediate stress responses in adult females (before and after menopause) in comparison to males. My thesis thus has two major foci: (1) What role(s) do catecholamines play in the embryonic heart?, and (2) Do catecholamines differentially influence cardiac function in aging male and female hearts? Initially, we sought to uncover the roles of adrenergic hormones in the embryonic heart by utilizing an adrenergic-deficient (Dbh-/-) mouse model. We found that adrenergic hormones influence heart development by stimulating expression of the gap junction protein, connexin 43, facilitating atrioventricular conduction, and helping to maintain cardiac rhythm. As development progresses, cardiac energy demands increase substantially, and oxidative phosphorylation becomes vital. Adrenergic hormones regulate metabolism in adults, thus we hypothesized they may stimulate energy metabolism during the embryonic/fetal transition period. We examined ATP, ADP, oxygen consumption rate, and extracellular acidification rates and found these metabolic indices were significantly decreased in Dbh-/- hearts compared to Dbh+/+ controls. We employed transmission electron microscopy of embryonic cardiomyocytes and found the mitochondria were significantly larger in Dbh-/- hearts compared to controls, and had more branch points. Taken together, these results suggest adrenergic hormones play a major role mediating the shift from predominantly anaerobic to aerobic metabolism during the embryonic/fetal transition period.Since there are known differential cardiac responses due to sex, age, and menopause to stress, we used echocardiography to measure left ventricular (LV) function in adult (9, 18 and 21 month) male and female mice (pre and postmenopausal) in response to epinephrine, and immobilization stress to investigate the roles of these factors. My results show 9-month premenopausal female mice display significantly decreased LV responsiveness to epinephrine compared to males, and an increased response to epinephrine due to age, especially in the premenopausal females. Similar LV function was also observed between postmenopausal females and males, and this pattern persisted after immobilization stress. I also investigated anatomical differences in the distribution of adrenergic cells within the heart comparing age, sex, and menopausal status. Notably, the density of cells derived from an adrenergic lineage in the heart was significantly increased in postmenopausal mice compared to age-matched males and cycling females. The selective re-appearance of adrenergic cells in the heart following menopause may provide an explanation for the differential stress responses observed in our system, and could have important clinical ramifications for stress-induced cardiomyopathies.
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Date Issued
2014
Identifier
CFE0005458, ucf:50373
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005458