|
Originally published In Press as doi:10.1194/jlr.M400010-JLR200 on April 21, 2004
Journal of Lipid Research, Vol. 45, 1279-1288, July 2004
Copyright © 2004 by American Society for Biochemistry and Molecular Biology
Overexpression of mitochondrial GPAT in rat hepatocytes leads to decreased fatty acid oxidation and increased glycerolipid biosynthesis
Daniel Lindén*, ,
Lena William-Olsson*,
Magdalena Rhedin*,
Anna-Karin Asztély*,
John C. Clapham* and
Sandra Schreyer1,*
* AstraZeneca R&D, Mölndal, Sweden
Wallenberg Laboratory for Cardiovascular Research, Göteborg University, Sweden
1 To whom correspondence should be addressed. e-mail: sandra.schreyer{at}astrazeneca.com
Glycerol-3-phosphate acyltransferase (GPAT) catalyses the first committed step in glycerolipid biosynthesis. The mitochondrial isoform (mtGPAT) is mainly expressed in liver, where it is highly regulated, indicating that mtGPAT may have a unique role in hepatic fatty acid metabolism. Because both mtGPAT and carnitine palmitoyl transferase-1 are located on the outer mitochondrial membrane, we hypothesized that mtGPAT directs fatty acyl-CoA away from ß-oxidation and toward glycerolipid synthesis. Adenoviral-mediated overexpression of murine mtGPAT in primary cultures of rat hepatocytes increased mtGPAT activity 2.7-fold with no compensatory effect on microsomal GPAT activity. MtGPAT overexpression resulted in a dramatic 80% reduction in fatty acid oxidation and a significant increase in hepatic diacylglycerol and phospholipid biosynthesis. Following lipid loading of the cells, intracellular triacylglycerol biosynthesis was also induced by mtGPAT overexpression. Changing an invariant aspartic acid residue to a glycine [D235G] in mtGPAT resulted in an inactive enzyme, which helps define the active site required for mammalian mtGPAT function. To determine if obesity increases hepatic mtGPAT activity, two models of rodent obesity were examined and shown to have >2-fold increased enzyme activity.
Overall, these results support the concept that increased hepatic mtGPAT activity associated with obesity positively contributes to lipid disorders by reducing oxidative processes and promoting de novo glycerolipid synthesis.
Abbreviations: CHO, Chinese hamster ovary; CPT-1, carnitine palmitoyl transferase-1; ER, endoplasmic reticulum; GPAT, glycerol-3-phosphate acyltransferase; MOI, multiplicity of infection; wt, wild type Supplementary key words glycerol-3-phosphate acyltransferase obesity triglyceride

CiteULike Complore Connotea Del.icio.us Digg Reddit Technorati What's this?
This article has been cited by other articles:

|
 |

|
 |
 
S. Sukumaran, R. I Barnes, A. Garg, and A. K Agarwal
Functional characterization of the human 1-acylglycerol-3-phosphate-O-acyltransferase isoform 10/glycerol-3-phosphate acyltransferase isoform 3
J. Mol. Endocrinol.,
June 1, 2009;
42(6):
469 - 478.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
K. Takeuchi and K. Reue
Biochemistry, physiology, and genetics of GPAT, AGPAT, and lipin enzymes in triglyceride synthesis
Am J Physiol Endocrinol Metab,
June 1, 2009;
296(6):
E1195 - E1209.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
C. A. Nagle, E. L. Klett, and R. A. Coleman
Hepatic triacylglycerol accumulation and insulin resistance
J. Lipid Res.,
April 1, 2009;
50(Supplement):
S74 - S79.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
O. Araki, H. Ying, X. G. Zhu, M. C. Willingham, and S. Y. Cheng
Distinct Dysregulation of Lipid Metabolism by Unliganded Thyroid Hormone Receptor Isoforms
Mol. Endocrinol.,
March 1, 2009;
23(3):
308 - 315.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
M. Prentki and S. R. M. Madiraju
Glycerolipid Metabolism and Signaling in Health and Disease
Endocr. Rev.,
October 1, 2008;
29(6):
647 - 676.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
R. E. Gimeno and J. Cao
Thematic Review Series: Glycerolipids. Mammalian glycerol-3-phosphate acyltransferases: new genes for an old activity
J. Lipid Res.,
October 1, 2008;
49(10):
2079 - 2088.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
S. Nishikawa, K. Doi, H. Nakayama, and K. Uetsuka
The Effect of Fasting on Hepatic Lipid Accumulation and Transcriptional Regulation of Lipid Metabolism Differs between C57BL/6J and BALB/cA Mice Fed a High-fat Diet
Toxicol Pathol,
October 1, 2008;
36(6):
850 - 857.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
Y. Q. Chen, M.-S. Kuo, S. Li, H. H. Bui, D. A. Peake, P. E. Sanders, S. J. Thibodeaux, S. Chu, Y.-W. Qian, Y. Zhao, et al.
AGPAT6 Is a Novel Microsomal Glycerol-3-phosphate Acyltransferase
J. Biol. Chem.,
April 11, 2008;
283(15):
10048 - 10057.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
J. Li, A. Nanayakkara, J. Jun, V. Savransky, and V. Y. Polotsky
Effect of deficiency in SREBP cleavage-activating protein on lipid metabolism during intermittent hypoxia
Physiol Genomics,
October 19, 2007;
31(2):
273 - 280.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
C. A. Nagle, J. An, M. Shiota, T. P. Torres, G. W. Cline, Z.-X. Liu, S. Wang, R. L. Catlin, G. I. Shulman, C. B. Newgard, et al.
Hepatic Overexpression of Glycerol-sn-3-phosphate Acyltransferase 1 in Rats Causes Insulin Resistance
J. Biol. Chem.,
May 18, 2007;
282(20):
14807 - 14815.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
M. R. Gonzalez-Baro, T. M. Lewin, and R. A. Coleman
Regulation of Triglyceride Metabolism II. Function of mitochondrial GPAT1 in the regulation of triacylglycerol biosynthesis and insulin action
Am J Physiol Gastrointest Liver Physiol,
May 1, 2007;
292(5):
G1195 - G1199.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
J. Li, V. Savransky, A. Nanayakkara, P. L. Smith, C. P. O'Donnell, and V. Y. Polotsky
Hyperlipidemia and lipid peroxidation are dependent on the severity of chronic intermittent hypoxia
J Appl Physiol,
February 1, 2007;
102(2):
557 - 563.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
S. J. Nuwayhid, M. Vega, P. D. Walden, and M. E. Monaco
Regulation of de novo phosphatidylinositol synthesis
J. Lipid Res.,
July 1, 2006;
47(7):
1449 - 1456.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
J. Li, M. Bosch-Marce, A. Nanayakkara, V. Savransky, S. K. Fried, G. L. Semenza, and V. Y. Polotsky
Altered metabolic responses to intermittent hypoxia in mice with partial deficiency of hypoxia-inducible factor-1{alpha}
Physiol Genomics,
May 16, 2006;
25(3):
450 - 457.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
D. Linden, L. William-Olsson, A. Ahnmark, K. Ekroos, C. Hallberg, H. P. Sjogren, B. Becker, L. Svensson, J. C. Clapham, J. Oscarsson, et al.
Liver-directed overexpression of mitochondrial glycerol-3-phosphate acyltransferase results in hepatic steatosis, increased triacylglycerol secretion and reduced fatty acid oxidation
FASEB J,
March 1, 2006;
20(3):
434 - 443.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
U. Edvardsson, A. Ljungberg, D. Linden, L. William-Olsson, H. Peilot-Sjogren, A. Ahnmark, and J. Oscarsson
PPAR{alpha} activation increases triglyceride mass and adipose differentiation-related protein in hepatocytes
J. Lipid Res.,
February 1, 2006;
47(2):
329 - 340.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
V. Aas, M. H. Rokling-Andersen, E. T. Kase, G. H. Thoresen, and A. C. Rustan
Eicosapentaenoic acid (20:5 n-3) increases fatty acid and glucose uptake in cultured human skeletal muscle cells
J. Lipid Res.,
February 1, 2006;
47(2):
366 - 374.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
L. E. Hammond, S. Neschen, A. J. Romanelli, G. W. Cline, O. R. Ilkayeva, G. I. Shulman, D. M. Muoio, and R. A. Coleman
Mitochondrial Glycerol-3-phosphate Acyltransferase-1 Is Essential in Liver for the Metabolism of Excess Acyl-CoAs
J. Biol. Chem.,
July 8, 2005;
280(27):
25629 - 25636.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
T. M. Onorato, S. Chakraborty, and D. Haldar
Phosphorylation of Rat Liver Mitochondrial Glycerol-3-phosphate Acyltransferase by Casein Kinase 2
J. Biol. Chem.,
May 20, 2005;
280(20):
19527 - 19534.
[Abstract]
[Full Text]
[PDF]
|
 |
|

|
 |

|
 |
 
T. M. Lewin, S. Wang, C. A. Nagle, C. G. Van Horn, and R. A. Coleman
Mitochondrial glycerol-3-phosphate acyltransferase-1 directs the metabolic fate of exogenous fatty acids in hepatocytes
Am J Physiol Endocrinol Metab,
May 1, 2005;
288(5):
E835 - E844.
[Abstract]
[Full Text]
[PDF]
|
 |
|
Copyright © 2004 by the American Society for Biochemistry and Molecular Biology.
|
Advertisement
Advertisement
|