T E M P O R A L R E G U L A T I O N O F P H O S P H AT I D Y L C H O L I N E B I O S Y N T H E S I S I N PERIPHERAL OSCILLATORS

ACOSTA-RODRÍGUEZ VA; SEBASTIAN MARQUEZ; GUIDO ME.

PUERTO MADRYN

Congreso; XLVIII Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2010

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

3?10% of transcriptome mostly involved in essential metabolicpathways is under circadian regulation. Circadian oscillators arepresent in different peripheral organs and tissues and even inimmortalized cell lines. We reported that the phospholipidsynthesis oscillates in synchronized fibroblast cultures under anintrinsic clock control. However, it was unknown whether thephosphatidylcholine (PC) metabolism was temporally regulated.To this end, we studied the temporal expression and activity ofCTP:phosphocholine cytidylyltranferase (CT), the key PCsynthesising enzyme. We found that higher labeled PC levelsobserved at 6.5 h after serum shock (SS) correlates with an increasein CT activity at this time. CT activity remains low and peaks againby 33 h after SS. We found detectable mRNA levels for all CTisoforms and a significant increase of CTα 1 mRNA at 3 h of SS byqPCR, returning to basal levels later on. In contrast the CTβ 2mRNA was found elevated between 6-18 h post SS. Thecontribution of CTα 1 to CTβ 2 was higher at all times (0-36h).Preliminary results show that CTα protein remains constant during36 h while CTb isoforms exhibit higher levels after 9 h SS. Resultssuggest that the PC biosynthesis is driven by a circadian clockoperating at different levels (enzyme activity/transcription, etc),and that CT isoforms are differentially regulated in synchronizedcells.