Temporal regulation of phosphatidylcholine biosynthesis in synchronized cultures of fibroblasts

ACOSTA-RODRÍGUEZ VA; GUIDO ME.; SEBASTIAN MARQUEZ

potrero de funes San Luis

Congreso; XLVIII Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2011

Circadian oscillators are present in different peripheral organs andtissues and even in immortalized cell lines. We reported that thephospholipid synthesis oscillates in synchronized fibroblast culturesunder an intrinsic clock control (Marquez et al., 2004). However,little is known about the temporal regulation of phosphatidylcholine(PC) metabolism. Here, we examined the daily variations in PClevels and expression of PC synthesizing enzymes in quiescent NIH3T3 cells synchronized by serum shock (SS). PC is mainlysynthesized through the Kennedy?s pathway and catalyzed bycholine kinase (CK), choline cytidylyltransferase (CT) and andcytidine phosphotransferase (CPT). We found a higher content oflabeled PC at 6.5 h after SS. We also found detectable mRNA levelsfor all CT isoforms, with higher expression of CTa at all times tested(0-36 h). Both CTa1 transcript and protein peaked at 3 h poststimulation, while CTb2 mRNA was higher at 9-12 h. We alsodetected increased levels of CTb isoform proteins during 9-18 h byWB. Preliminary results showed that CKa transcript assessed byqPCR is elevated during first 18 h post-synchronization while CKbmRNA remains constant during 36 h examined. Results suggest thatsynchronized fibroblasts exhibit temporal variations in PC contentwhich could be due, at least in part, to changes in the expression ofCK and CT enzymes.