GLYCEROL-3-P ACYLTRANSFERASE 2 STIMULATES THE SYNTHESIS OF ARACHIDONIC-ACID-RICH

CATTANEO, ER; PELLON-MAISON M; COLEMAN, RA; GONZALEZ-BARó MR

Puerto Madryn, Argentina

Congreso; XLVI Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2010

SAIB

Glycerol-3-phosphate acyltransferase 2 (GPAT2) is a mitochondrial GPAT isoform highly expressed in testis. GPAT catalyzes the first and committed step in de novo glycerolipid synthesis. In particular GPAT2 has no preference for saturated acyl- CoA substrates, so we hypothesized that it would direct the synthesis of triacylglycerols (TAG) rich in polyunsaturated fatty acids (PUFA) involved in the traffic and metabolism of PUFA in testis. We have previously shown that GPAT2 overexpression in CHOK1 cells increased TAG content. To determine the specific role of GPAT2 we used GPAT2-overexpressing CHOK1 cells to measure GPAT and AGPAT activities using different acyl-CoAs and determine the fatty acid (FA) composition of TAG extracted from cells incubated with 10% FBS DMEM (control media) or with media supplemented with different FA. GPAT2 overexpression increased the incorporation of 18:1n9 and 18:2n9, respecting to control cells, when cells were incubated in media supplemented with 50 ìM of the corresponding exogenous FA. When cells were incubated in control media GPAT2-overexpressing cells increased the incorporation of arachidonic acid into TAG. Consistently, in GPAT2 overexpressing cells both GPAT and AGPAT activities increased 2 fold only when arachidonoyl-CoA was used as a substrate. Our results suggest that GPAT2 is involved in arachidonic acid enriched TAG synthesis.de novo glycerolipid synthesis. In particular GPAT2 has no preference for saturated acyl- CoA substrates, so we hypothesized that it would direct the synthesis of triacylglycerols (TAG) rich in polyunsaturated fatty acids (PUFA) involved in the traffic and metabolism of PUFA in testis. We have previously shown that GPAT2 overexpression in CHOK1 cells increased TAG content. To determine the specific role of GPAT2 we used GPAT2-overexpressing CHOK1 cells to measure GPAT and AGPAT activities using different acyl-CoAs and determine the fatty acid (FA) composition of TAG extracted from cells incubated with 10% FBS DMEM (control media) or with media supplemented with different FA. GPAT2 overexpression increased the incorporation of 18:1n9 and 18:2n9, respecting to control cells, when cells were incubated in media supplemented with 50 ìM of the corresponding exogenous FA. When cells were incubated in control media GPAT2-overexpressing cells increased the incorporation of arachidonic acid into TAG. Consistently, in GPAT2 overexpressing cells both GPAT and AGPAT activities increased 2 fold only when arachidonoyl-CoA was used as a substrate. Our results suggest that GPAT2 is involved in arachidonic acid enriched TAG synthesis.