“Temporal regulation of phosphatidylcholine biosynthesis in synchronized cultures of fibroblasts“.

ACOSTA RODRÍGUEZ VA; MÁRQUEZ S; GUIDO ME

Potrero de los Funes, San Luis

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

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB).

Circadian oscillators are present in different peripheral organs and tissues and even in immortalized cell lines. We reported that the phospholipid synthesis oscillates in synchronized fibroblast cultures under 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 PC levels and expression of PC synthesizing enzymes in quiescent NIH 3T3 cells synchronized by serum shock (SS). PC is mainly synthesized through the Kennedy’s pathway and catalyzed by choline kinase (CK), choline cytidylyltransferase (CT) and and cytidine phosphotransferase (CPT). We found a higher content of labeled PC at 6.5 h after SS. We also found detectable mRNA levels for all CT isoforms, with higher expression of CTa at all times tested (0-36 h). Both CTa1 transcript and protein peaked at 3 h post stimulation, while CTb2 mRNA was higher at 9-12 h. We also detected increased levels of CTb isoform proteins during 9-18 h by WB. Preliminary results showed that CKa transcript assessed by qPCR is elevated during first 18 h post-synchronization while CKb mRNA remains constant during 36 h examined. Results suggest that synchronized fibroblasts exhibit temporal variations in PC content which could be due, at least in part, to changes in the expression of CK and CT enzymes.