Glycerol-3-phosphate acyltransferase 2: a mitochondrial testicular isoform involved in cellular proliferation

CATTÁNEO ER; PELLON-MAISON M; COLEMAN RA; GONZALEZ-BARO MR

EEUU

Conferencia; Gordon Research Conference “Molecular and Cellular Biology of Lipids”.; 2009

Gordon Research Conferences

Glycerol-3-phosphate acyltransferase 2: a mitochondrial testicular isoform involved in cellular proliferation   Glycerol-3-phosphate acyltransferase (GPAT) catalyzes the first and committed step in de novo glycerolipid synthesis. In mammals, several isoforms have been described         with different cellular localization and kinetic properties. The mitochondrial isoform GPAT2 is highly expressed in rat testis and has no preference for saturated acyl-CoA substrates, so we hypothesized that it would be involved in the synthesis of triacylglycerols (TAG) rich in unsaturated fatty acids, required for the proper testicular function. Northern blot analysis showed that GPAT2 mRNA is expressed in seminiferous tubules, specifically in germ-line cells. The expression increases with age of the rat from 19 to 60-days of age, and it is associated with the onset of spermatogenesis. Transient GPAT2 overexpression in CHOK1 cells increased the TAG content compared to GPAT1-overexpressing and control cells. Oil-red-O staining showed that lipid droplets were larger but similar in number. CHO-K1 cells stably overexpressing GPAT2 2-fold had an increased proliferation rate compared to GPAT1-overexpressing and control cells. Crystal violet proliferation assays showed that, after 65 hr, the cell number was ~30% higher in GPAT2-overexpressing cells. Our results indicate that GPAT2 is involved in TAG synthesis related to spermatic cells, and that some metabolite/s derived from its activity may be involved in the testis’ processes of cellular proliferation.  Supported by CONICET PIP 6503 and NIH TW06034