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Published on: July 18, 2019
An induction in hepatic HDL secretion associated with reduced ATPase expression
Nihar R Pandey1, Joanna Renwick, Seham Rabaa
1Lipoprotein and Atherosclerosis Research Group, The University of Ottawa Heart Institute, Ottawa, Ontario K1Y 4W7, Canada.
The American Journal of Pathology
|September 1, 2009
Summary
Linoleic acid-phospholipids enhance high-density lipoprotein (HDL) secretion by liver cells. This process involves regulating ATP-dependent proteins and altering HDL particle migration, impacting cholesterol transport.
Area of Science:
- Biochemistry
- Cell Biology
- Metabolic Research
Background:
- High-density lipoprotein (HDL) plays a crucial role in reverse cholesterol transport.
- Apolipoprotein A-I (apoA-I) is the main protein component of HDL.
- Hepatic secretion of HDL is a key step in maintaining cholesterol homeostasis.
Purpose of the Study:
- To investigate the relationship between apoA-I accumulation in cell media and membrane ATPase expression.
- To determine the role of linoleic acid-phospholipids in regulating HDL secretion.
- To explore the involvement of ATP-binding cassette (ABC) transporters in this process.
Main Methods:
- Treatment of HepG2 cells with dilinoeoylphosphatidylcholine (DLPC).
- Assessment of apoA-I secretion levels.
- Measurement of cell surface F1-ATPase expression and cellular ABC transporter protein levels (ABCA1, ABCG1).
- Inhibition and induction of ABC transporter activity.
Main Results:
- DLPC treatment increased apoA-I secretion fourfold.
- DLPC reduced F1-ATPase expression and decreased cellular ABCA1 and ABCG1 protein levels.
- ABC transporter inhibition enhanced DLPC's effect on apoA-I secretion, while increasing ABC transporter levels blocked it.
- DLPC shifted HDL secretion from prebeta-migrating to alpha-migrating particles.
Conclusions:
- Linoleic acid-phospholipid-induced hepatic HDL secretion is linked to the expression and function of membrane ATP-metabolizing proteins.
- Regulation of ATPases and ABC transporters is critical for modulating apoA-I secretion and HDL particle composition.
- These findings provide insights into mechanisms controlling HDL metabolism and cholesterol efflux.
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