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HEPATIC LIPASE REGULATES LIPOPROTEIN TRAFFICKING IN HEPATOCYTES

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Date Issued:
2015
Abstract/Description:
The production of very low density lipoprotein and high density lipoprotein particles by the liver is a tightly regulated process, which begins with synthesis and assembly of core protein components in the rough endoplasmic reticulum. Factors influencing the production and metabolism of these particles are of immediate medical relevance, as their malfunction or hyperactivity can lead to an assortment of disease states. Hepatic lipase is a secreted liver enzyme, with many previously described roles in the metabolism and clearance of both high and low density lipoproteins. Increased production and assembly of this enzyme is an indicator of metabolic dysfunction, while its absence or insufficiency leads to pre-mature atherosclerosis and death. The present study shows that this enzyme's role in lipoprotein metabolism is not confined to the degradation and clearance of these particles after they have been secreted. Experiments using co-immunoprecipitation targeted at hepatic lipase demonstrate that this protein interacts with ApoA1 and ApoB100, the core protein components of HDL and VLDL respectively, at the ER level in hepatocytes, as part of an enormous multi-subunit protein complex. This interaction with ApoA1 leads to decreased competence of hepatocytes to secrete HDL, which confers a pro-atherogenic phenotype. Analysis of ER to Golgi VLDL transport vesicles, produced with a cell-free in vitro budding assay, has revealed that hepatic lipase is co-secreted between these compartments with immature VLDL particles. Further analysis of cytosol isolated from hepatocytes demonstrates an interaction between hepatic lipase and the LDL-receptor related protein in a post-Golgi vesicle; the significance of which will be investigated in future studies.
Title: HEPATIC LIPASE REGULATES LIPOPROTEIN TRAFFICKING IN HEPATOCYTES.
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Name(s): Thibeaux, Simeon, Author
Siddiqi, Shadab, Committee Chair
University of Central Florida, Degree Grantor
Type of Resource: text
Date Issued: 2015
Publisher: University of Central Florida
Language(s): English
Abstract/Description: The production of very low density lipoprotein and high density lipoprotein particles by the liver is a tightly regulated process, which begins with synthesis and assembly of core protein components in the rough endoplasmic reticulum. Factors influencing the production and metabolism of these particles are of immediate medical relevance, as their malfunction or hyperactivity can lead to an assortment of disease states. Hepatic lipase is a secreted liver enzyme, with many previously described roles in the metabolism and clearance of both high and low density lipoproteins. Increased production and assembly of this enzyme is an indicator of metabolic dysfunction, while its absence or insufficiency leads to pre-mature atherosclerosis and death. The present study shows that this enzyme's role in lipoprotein metabolism is not confined to the degradation and clearance of these particles after they have been secreted. Experiments using co-immunoprecipitation targeted at hepatic lipase demonstrate that this protein interacts with ApoA1 and ApoB100, the core protein components of HDL and VLDL respectively, at the ER level in hepatocytes, as part of an enormous multi-subunit protein complex. This interaction with ApoA1 leads to decreased competence of hepatocytes to secrete HDL, which confers a pro-atherogenic phenotype. Analysis of ER to Golgi VLDL transport vesicles, produced with a cell-free in vitro budding assay, has revealed that hepatic lipase is co-secreted between these compartments with immature VLDL particles. Further analysis of cytosol isolated from hepatocytes demonstrates an interaction between hepatic lipase and the LDL-receptor related protein in a post-Golgi vesicle; the significance of which will be investigated in future studies.
Identifier: CFH0004736 (IID), ucf:45366 (fedora)
Note(s): 2015-05-01
B.S.
Medicine, Burnett School of Biomedical Sciences
Bachelors
This record was generated from author submitted information.
Subject(s): Hepatic lipase
Lipoprotein
Trafficking
ApoA1
Hepatocytes
Persistent Link to This Record: http://purl.flvc.org/ucf/fd/CFH0004736
Restrictions on Access: campus 2020-04-01
Host Institution: UCF

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