Elucidating mechanisms of acetyl-L-carnitine metabolism in mammalian cells
Abstract/Contents
- Abstract
- In eukaryotes carnitine is best known for its ability to shuttle esterified fatty acids across mitochondrial membranes for -oxidation. It also returns, in the form of acetyl-L-carnitine (LAC), some of the resulting acetyl groups for post-translational protein modification to the nucleocytoplasm. Earlier work revealed that LAC supplementation has unexpected antidepressant effects in mammals while implicating an epigenetic mechanism for this property. To explain how exogenous LAC influences mammalian cell metabolism, we synthesized isotope-labeled forms of LAC and its analogs. In cultures of glucose-limited U87MG cells, exogenous LAC contributed more robustly to intracellular acetyl-CoA pools than did b-hydroxybutyrate, the predominant circulating ketone body in mammals. The fact that most LAC-derived acetyl-CoA is cytosolic is evident from strong biosynthetic labeling of fatty acids in U87MG cells by exogenous 13C2-acetyl-L-carnitine. Addition of d3-acetyl-L-carnitine increases the supply of acetyl-CoA for epigenetic uses due to its expectedly strong kinetic isotope effect on acetyl-CoA carboxylase, the first committed step in fatty acid biosynthesis. Surprisingly, whereas cytosolic carnitine acetyltransferase (CRAT) is believed to catalyze acetyl group transfer from LAC to Coenzyme A, CRAT-/- U87MG cells were unimpaired in their ability to assimilate exogenous LAC into acetyl-CoA. We identified carnitine octanoyltransferase (CROT) as the key enzyme in this process, implicating a role for peroxisomes in efficient LAC utilization. By engineering a carnitine analog with markedly superior selectivity for CROT over CRAT, our work has also opened the door to further chemical genetic investigations of a new pathway for supplying acetyl-CoA to certain glucose-starved cells.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2022; ©2022 |
| Publication date | 2022; 2022 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Hsu, Jake Wei-En |
|---|---|
| Degree supervisor | Khosla, Chaitan, 1964- |
| Thesis advisor | Khosla, Chaitan, 1964- |
| Thesis advisor | Abu-Remaileh, Monther |
| Thesis advisor | Swartz, James R |
| Degree committee member | Abu-Remaileh, Monther |
| Degree committee member | Swartz, James R |
| Associated with | Stanford University, Department of Chemical Engineering |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Jake Hsu. |
|---|---|
| Note | Submitted to the Department of Chemical Engineering. |
| Thesis | Thesis Ph.D. Stanford University 2022. |
| Location | https://purl.stanford.edu/rc402td7775 |
Access conditions
- Copyright
- © 2022 by Jake Wei-En Hsu
- License
- This work is licensed under a Creative Commons Attribution 3.0 Unported license (CC BY).
Also listed in
Loading usage metrics...