Transcriptional regulation of mouse Gpat2 in comparison to the human isoform

GARCIA FABIANI, M.B.; PELLON-MAISON, M.; CATTANEO, E.R.; MONTANARO, M.A.; GONZALEZ BARO, M.R.

Mendoza

Congreso; XLVII Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2012

SAIB

The first step in de novo glycerolipid synthesis is catalyzed by glycerol-3-phosphate acyltransferase (GPAT). In mammals, at least four GPAT isoforms have been described, differing in their cell and tissue locations and functions. GPAT1, 3 and 4 are expressed in lipogenic organs like liver and adipose tissue. Unlike the other 3 isoforms, GPAT2, located in the outer mitochondrial membrane, is highly expressed in rat and mouse testis and certain cancer cells, tissues that do not specialize in lipid synthesis and storage. Gpat2 transcription in testis peaks at the beginning of rat spermatogenesis indicating transcriptional regulation, possibly related to hormones. We cloned the murine Gpat2 promoter region (~6.7, 3.4 and 1.3kpb upstream from the transcription initiation site) into a luciferase-reporter vector and transfected them into CHO-K1 cells. Only the 3.4 kbp construct significantly activated transcription, so we used it for further experiments. Among several hormones, cis-9-retinoic acid increased the promoter’s activity, consistent with its role in testis function. In silico data indicated epigenetic regulation for human GPAT2 gene. Human and mouse cell lines that do not express GPAT2 were treated with a DNA methylation inhibitor and GPAT2 expression was increased only in the human cell lines, evidencing DNA methylation as a possible regulatory GPAT2 expression mechanism in humans.