Mitochondrial Glycerol Phosphate Acyltransferase Directs the Incorporation of Exogenous Fatty Acids into Triacylglycerol

The mitochondrial isoform of glycerol-3-phosphate acyltransferase (GPAT), the first step in glycerolipid synthesis, is up-regulated by insulin and by high carbohydrate feeding via SREBP-1c, suggesting that it plays a role in triacylglycerol synthesis. To test this hypothesis, we overexpressed mitoch...

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Detalles Bibliográficos
Autores principales: Igal, Rubén Ariel, Wang, Shuli, Gonzalez-Baró, Maria, Coleman, Rosalind A.
Formato: Articulo
Lenguaje:Inglés
Publicado: 2001
Materias:
Ciencias Médicas
glycerol-3-phosphate acyltransferase
glycerolipid synthesis
insulin
carbohydrate
Acceso en línea:http://sedici.unlp.edu.ar/handle/10915/83437
Aporte de:
SEDICI (UNLP) de Universidad Nacional de La Plata
id I19-R120-10915-83437
record_format dspace
institution Universidad Nacional de La Plata
institution_str I-19
repository_str R-120
collection SEDICI (UNLP)
language Inglés
topic Ciencias Médicas
glycerol-3-phosphate acyltransferase
glycerolipid synthesis
insulin
carbohydrate
spellingShingle Ciencias Médicas
glycerol-3-phosphate acyltransferase
glycerolipid synthesis
insulin
carbohydrate
Igal, Rubén Ariel
Wang, Shuli
Gonzalez-Baró, Maria
Coleman, Rosalind A.
Mitochondrial Glycerol Phosphate Acyltransferase Directs the Incorporation of Exogenous Fatty Acids into Triacylglycerol
topic_facet Ciencias Médicas
glycerol-3-phosphate acyltransferase
glycerolipid synthesis
insulin
carbohydrate
description The mitochondrial isoform of glycerol-3-phosphate acyltransferase (GPAT), the first step in glycerolipid synthesis, is up-regulated by insulin and by high carbohydrate feeding via SREBP-1c, suggesting that it plays a role in triacylglycerol synthesis. To test this hypothesis, we overexpressed mitochondrial GPAT in Chinese hamster ovary (CHO) cells. When GPAT was overexpressed 3.8-fold, triacylglycerol mass was 2.7-fold higher than in control cells. After incubation with trace [14C]oleate (∼3 μM), control cells incorporated 4.7-fold more label into phospholipid than triacylglycerol, but GPAT-overexpressing cells incorporated equal amounts of label into phospholipid and triacylglycerol. In GPAT-overexpressing cells, the incorporation of label into phospholipid, particularly phosphatidylcholine, decreased 30%, despite normal growth rate and phospholipid content, suggesting that exogenous oleate was directed primarily toward triacylglycerol synthesis. Transiently transfected HEK293 cells that expressed a 4.4-fold increase in GPAT activity incorporated 9.7-fold more [14C]oleate into triacylglycerol compared with control cells, showing that the effect of GPAT overexpression was similar in two different cell types that had been transfected by different methods. When the stable, GPAT-overexpressing CHO cells were incubated with 100 μM oleate to stimulate triacylglycerol synthesis, they incorporated 1.9-fold more fatty acid into triacylglycerol than did the control cells. Confocal microscopy of CHO and HEK293 cells transfected with the GPAT-FLAG construct showed that GPAT was located correctly in mitochondria and was not present elsewhere in the cell. These studies indicate that overexpressed mitochondrial GPAT directs incorporation of exogenous fatty acid into triacylglycerol rather than phospholipid and imply that (a) mitochondrial GPAT and lysophosphatidic acid acyltransferase produce a separate pool of lysophosphatidic acid and phosphatidic acid that must be transported to the endoplasmic reticulum where the terminal enzymes of triacylglycerol synthesis are located, and (b) this pool remains relatively separate from the pool of lysophosphatidic acid and phosphatidic acid that contributes to the synthesis of the major phospholipid species.
format Articulo
Articulo
author Igal, Rubén Ariel
Wang, Shuli
Gonzalez-Baró, Maria
Coleman, Rosalind A.
author_facet Igal, Rubén Ariel
Wang, Shuli
Gonzalez-Baró, Maria
Coleman, Rosalind A.
author_sort Igal, Rubén Ariel
title Mitochondrial Glycerol Phosphate Acyltransferase Directs the Incorporation of Exogenous Fatty Acids into Triacylglycerol
title_short Mitochondrial Glycerol Phosphate Acyltransferase Directs the Incorporation of Exogenous Fatty Acids into Triacylglycerol
title_full Mitochondrial Glycerol Phosphate Acyltransferase Directs the Incorporation of Exogenous Fatty Acids into Triacylglycerol
title_fullStr Mitochondrial Glycerol Phosphate Acyltransferase Directs the Incorporation of Exogenous Fatty Acids into Triacylglycerol
title_full_unstemmed Mitochondrial Glycerol Phosphate Acyltransferase Directs the Incorporation of Exogenous Fatty Acids into Triacylglycerol
title_sort mitochondrial glycerol phosphate acyltransferase directs the incorporation of exogenous fatty acids into triacylglycerol
publishDate 2001
url http://sedici.unlp.edu.ar/handle/10915/83437
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AT wangshuli mitochondrialglycerolphosphateacyltransferasedirectstheincorporationofexogenousfattyacidsintotriacylglycerol
AT gonzalezbaromaria mitochondrialglycerolphosphateacyltransferasedirectstheincorporationofexogenousfattyacidsintotriacylglycerol
AT colemanrosalinda mitochondrialglycerolphosphateacyltransferasedirectstheincorporationofexogenousfattyacidsintotriacylglycerol
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