Functions of rat acyl-CoA synthetases in bacteria and mammalian cells

Public Deposited
Analytics

Downloadable Content

Download PDF
Request Version for Screen Reader
Last Modified
  • March 20, 2019
Creator
  • Li, Lei
    • Affiliation: Gillings School of Global Public Health, Department of Nutrition
Abstract
  • Long chain acyl-CoA synthetase (ACSL) activates long chain fatty acids in the initial step of lipid metabolism, and provides substrates for both anabolic and catabolic pathways. Dysregulation of fatty acid partitioning between these opposing pathways results in cellular lipid accumulation, which may cause obesity and lipotoxicity. We hypothesized that ACSL isoforms play a critical role in fatty acid channeling into different metabolic pathways and that regulation of ACSL may change the fatty acid channeling. This dissertation describes three independent projects that examined the function of rat ACSL isoforms in lipid metabolism and their acute regulation by phosphorylation. Using an E. coli model with its endogenous ACSL mutated (fadD), we demonstrated that although all rat ACSL isoforms partially rescued fatty acid transport, beta-oxidation, and phospholipid synthesis, only ACSL5 supported growth on oleate as the sole energy and carbon source. This study supported the hypothesis that ACSL isoforms are functionally different and prompted the subsequent study on function of ACSL1 in lipid metabolism. Using an adenovirus that carries an ACSL1 cDNA, we overexpressed rat ACSL1 in primary hepatocytes and examined the effects on metabolic pathways. Consistent with our hypothesis that individual ACSLs partition fatty acid, we found that ACSL1 overexpression increased oleate incorporation into diacylglycerol and phospholipids, but not triacylglycerol, and decreased cholesterol ester synthesis. Together with the finding from a previous study in our lab with ACSL5 overexpression, these data provided direct evidence of different fatty acid channeling by ACSLs. We then studied the potential acute phosphorylation regulation of ACSL1 and ACSL5 in 3T3-L1 adipocytes and hepatocytes. We identified phosphorylated threonine 192 on ACSL5, and detected ACSL5 and ACSL1 with phosphorylated serine residues. These data were the first to show that ACSL could be phosphorylated, and that phosphorylation could occur on distinct residues among different ACSL isoforms. The importance of this dissertation also lies in directing future research on mechanisms of specific role of individual ACSL isoforms and potential clinical implication for obesity and its related metabolic diseases.
Date of publication
DOI
Resource type
Rights statement
  • In Copyright
Advisor
  • Coleman, Rosalind
Language
Access right
  • Open access
Date uploaded
  • October 19, 2010

Relations

Parents:

This work has no parents.

Items

Thumbnail Title Date Uploaded Visibility Actions
file details Functions of rat acyl-CoA synthetases in bacteria and mammalian cells 2019-04-12 Public Download