GPAT2 silencing alters arachidonate distribution in MDA-MB-231 cells

CATTANEO, E.R.; GUIJAS, C.; MONTANARO, M.A.; QUIROGA, I.Y.; BALSINDE, J.; PELLON-MAISON, M.; GONZALEZ BARO, M.R.

Rosario

Congreso; L Reunion Anual de SAIB; 2014

SAIB

Glycerol-3-phosphate acyltransferases (GPATs) catalyzethe first step in the de novo glycerolipid biosynthesis. Although mouse GPAT2gene was first cloned by sequence homology to GPAT1, we have demonstrated thatGPAT2 is notably different to the other GPATs. In order to elucidate its rolein lipid metabolism, we explored the arachidonate (AA) distribution amongmembrane phospholipids in MDA-MB-231 control (scr-MDA) versus GPAT2 stablyknocked down (sh-MDA) cells. Fatty acid composition of phospholipids (PL) andtriacylglycerols (TG) was evaluated by GLC after a 3-day- incubation with 50 µMAA; AA content in PL and TG of sh-MDA cells was increased (13.6% vs. 6.8% and13% vs. 3 % respectively). Endogenous AA-containing PL species were easured byLC/MS/MS. sh-MDA cells showed higher amounts of most AA-containing PC and PEspecies and lower amounts of (18:1/20:4)PI and (18:2/20:4)PI compared to scr-MDAcells. 2[H]-AA incubation for 30 min showed that sh-MDA cells incorporatedhigher amounts of AA in PC species and lower amounts in (18:0/ 2H 20:4)-PI and(18:1/2H20:4)-PI than scr-MDA cells. Phospholipase A specific activity was alsomeasured and it was 50% lower in sh-MDA than in scr-MDA cells. In conclusion,GPAT2 expression in MDA-MB-231 cells diminished AA content in PC and PE andincorporation of exogenous AA in PC. Results presented heresuggest a novel enzymatic activity for GPAT2.