Characterization of the murine CTP:phosphocholine cytidylyltransferase beta gene promoter

MARCUCCI H; ELENA C; BANCHIO C

Mar del Plata (Argentina)

Congreso; XLIII Reunión Anual. Sociedad Argentina en Investigación Bioquímica y Biología Molecular. SAIB.; 2007

SAIB

  CTP:phosphocholine cytidylyltransferase (CCT) is a key regulatory enzyme in phosphatidylcholine (PC) biosynthesis by the Kennedy pathway. In mammals, there are two genes that encode enzymes that catalyze this reaction: Pcyt1a for CCTa, and Pcyt1b for CCTb isoforms. In mice, two isoforms named CCTb2 and CCTb3 can be generated from the Pcyt1b gene. We characterized two promoters that drive the expression of each CCTb isoforms (CCTb2 and CCTb3). The promoters were isolated from mouse DNA and its activity delineated by luciferase reporter assay and gel-shift analysis in Neuro2A (mouse neuroblastoma), TM4 (Sertoli) and C3H10T1/2 (mouse embryo fibroblast) cells. We also mapped by primer extension the transcription start sites of both promoters. The physiological role of CCTb is not clear, however, previous report have shown that the expression of CCTb2 enhance during neurite outgrowth and CCTb2 specific knockout mice revealed an essential role for this isoform in ovary maturation and in the maintenance of sperm production. To identify the transcription factors that bind to the CCTb2 promoter and regulate its expression we performed EMSA and DNasaI footprinting. Our results show that the expression of the CCTb isoforms is driven by two alternatives promoters and we propose that AP1 as a transcription factor that could regulate the expression of CCTb2 in brain.