CIRCADIAN VARIATION IN PHOSPHATIDYLCHOLINE CONTENT AND SYNTHESIZING ENZYME EXPRESSION IN MOUSE LIVER

GORNE, LUCAS D.; ACOSTA RODRIGUEZ, VICTORIA A.; GUIDO, MARIO E.

Potrero de los Funes, San Luis

Congreso; 47 Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2011

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular - SAIB -

Previous studies showed a circadian regulation in the biosynthesis of phospholipids in the vertebrate nervous system as well as in an immortalized cell line (Guido et al., 2001; Marquez et al., 2004). The circadian control of phospholipid synthesis and specifically of phosphatidylcholine (PC), the most abundant lipid in all eukaryotic cells, is slightly known. In the present work, we investigated the temporal variation in the membrane phospholipid composition, mainly focused in PC as well as in the expression of its synthesizing enzymes choline kinase (CK) and cytidylyltransferase (CCT) in mammalian peripheral tissues. For this, C57BL/6J mice were exposed to a 12:12 h light dark (LD) cycle or kept in constant dark (DD), killed at different times while livers and testes were dissected out and collected for further assays. mRNAs levels were determined by real-time qPCR using the clock gene Bmal1 as a circadian marker. In testes, we did not observe any temporal variation in lipid composition, expression of PC synthesis enzymes or Bmal1 mRNA, under any illumination condition tested. However, in the liver, we found a significant change in levels of CKa mRNA, in content of PI, PC and in the ratio PC/PE in DD. These results strongly suggest that there is a close relationship between clock driven-mechanisms and phospholipid metabolism in peripheral tissues of synchronized mice.