Carnitine octanoyltransferase is important for the assimilation of exogenous acetyl-L-carnitine into acetyl-CoA in mammalian cells
In eukaryotes, carnitine is best known for its ability to shuttle esterified fatty acids across mitochondrial membranes for β-oxidation. It also returns to the cytoplasm, in the form of acetyl-L-carnitine (LAC), some of the resulting acetyl groups for posttranslational protein modification and lipid...
Autores principales: | , , , , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
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American Society for Biochemistry and Molecular Biology
2022
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9898754/ https://www.ncbi.nlm.nih.gov/pubmed/36587768 http://dx.doi.org/10.1016/j.jbc.2022.102848 |
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author | Hsu, Jake Fatuzzo, Nina Weng, Nielson Michno, Wojciech Dong, Wentao Kienle, Maryline Dai, Yuqin Pasca, Anca Abu-Remaileh, Monther Rasgon, Natalie Bigio, Benedetta Nasca, Carla Khosla, Chaitan |
author_facet | Hsu, Jake Fatuzzo, Nina Weng, Nielson Michno, Wojciech Dong, Wentao Kienle, Maryline Dai, Yuqin Pasca, Anca Abu-Remaileh, Monther Rasgon, Natalie Bigio, Benedetta Nasca, Carla Khosla, Chaitan |
author_sort | Hsu, Jake |
collection | PubMed |
description | In eukaryotes, carnitine is best known for its ability to shuttle esterified fatty acids across mitochondrial membranes for β-oxidation. It also returns to the cytoplasm, in the form of acetyl-L-carnitine (LAC), some of the resulting acetyl groups for posttranslational protein modification and lipid biosynthesis. While dietary LAC supplementation has been clinically investigated, its effects on cellular metabolism are not well understood. 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 glioma cells, exogenous LAC contributed more robustly to intracellular acetyl-CoA pools than did β-hydroxybutyrate, the predominant circulating ketone body in mammals. The fact that most LAC-derived acetyl-CoA is cytosolic is evident from strong labeling of fatty acids in U87MG cells by exogenous (13)C(2)-acetyl-L-carnitine. We found that the addition of d(3)-acetyl-L-carnitine increases the supply of acetyl-CoA for cytosolic posttranslational modifications due to its strong kinetic isotope effect on acetyl-CoA carboxylase, the first committed step in fatty acid biosynthesis. Surprisingly, whereas cytosolic carnitine acetyltransferase 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 as the key enzyme in this process, implicating a role for peroxisomes in efficient LAC utilization. Our work has opened the door to further biochemical investigations of a new pathway for supplying acetyl-CoA to certain glucose-starved cells. |
format | Online Article Text |
id | pubmed-9898754 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2022 |
publisher | American Society for Biochemistry and Molecular Biology |
record_format | MEDLINE/PubMed |
spelling | pubmed-98987542023-02-09 Carnitine octanoyltransferase is important for the assimilation of exogenous acetyl-L-carnitine into acetyl-CoA in mammalian cells Hsu, Jake Fatuzzo, Nina Weng, Nielson Michno, Wojciech Dong, Wentao Kienle, Maryline Dai, Yuqin Pasca, Anca Abu-Remaileh, Monther Rasgon, Natalie Bigio, Benedetta Nasca, Carla Khosla, Chaitan J Biol Chem Research Article In eukaryotes, carnitine is best known for its ability to shuttle esterified fatty acids across mitochondrial membranes for β-oxidation. It also returns to the cytoplasm, in the form of acetyl-L-carnitine (LAC), some of the resulting acetyl groups for posttranslational protein modification and lipid biosynthesis. While dietary LAC supplementation has been clinically investigated, its effects on cellular metabolism are not well understood. 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 glioma cells, exogenous LAC contributed more robustly to intracellular acetyl-CoA pools than did β-hydroxybutyrate, the predominant circulating ketone body in mammals. The fact that most LAC-derived acetyl-CoA is cytosolic is evident from strong labeling of fatty acids in U87MG cells by exogenous (13)C(2)-acetyl-L-carnitine. We found that the addition of d(3)-acetyl-L-carnitine increases the supply of acetyl-CoA for cytosolic posttranslational modifications due to its strong kinetic isotope effect on acetyl-CoA carboxylase, the first committed step in fatty acid biosynthesis. Surprisingly, whereas cytosolic carnitine acetyltransferase 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 as the key enzyme in this process, implicating a role for peroxisomes in efficient LAC utilization. Our work has opened the door to further biochemical investigations of a new pathway for supplying acetyl-CoA to certain glucose-starved cells. American Society for Biochemistry and Molecular Biology 2022-12-30 /pmc/articles/PMC9898754/ /pubmed/36587768 http://dx.doi.org/10.1016/j.jbc.2022.102848 Text en © 2022 The Authors https://creativecommons.org/licenses/by/4.0/This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Research Article Hsu, Jake Fatuzzo, Nina Weng, Nielson Michno, Wojciech Dong, Wentao Kienle, Maryline Dai, Yuqin Pasca, Anca Abu-Remaileh, Monther Rasgon, Natalie Bigio, Benedetta Nasca, Carla Khosla, Chaitan Carnitine octanoyltransferase is important for the assimilation of exogenous acetyl-L-carnitine into acetyl-CoA in mammalian cells |
title | Carnitine octanoyltransferase is important for the assimilation of exogenous acetyl-L-carnitine into acetyl-CoA in mammalian cells |
title_full | Carnitine octanoyltransferase is important for the assimilation of exogenous acetyl-L-carnitine into acetyl-CoA in mammalian cells |
title_fullStr | Carnitine octanoyltransferase is important for the assimilation of exogenous acetyl-L-carnitine into acetyl-CoA in mammalian cells |
title_full_unstemmed | Carnitine octanoyltransferase is important for the assimilation of exogenous acetyl-L-carnitine into acetyl-CoA in mammalian cells |
title_short | Carnitine octanoyltransferase is important for the assimilation of exogenous acetyl-L-carnitine into acetyl-CoA in mammalian cells |
title_sort | carnitine octanoyltransferase is important for the assimilation of exogenous acetyl-l-carnitine into acetyl-coa in mammalian cells |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9898754/ https://www.ncbi.nlm.nih.gov/pubmed/36587768 http://dx.doi.org/10.1016/j.jbc.2022.102848 |
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