Diverse glycerolipid synthesizing enzymes contribute to the daily rhythms in phospholipid synthesis

ACOSTA-RODRíGUEZ VA; MARQUEZ S; SALVADOR G; PASQUARé S; GORNé LD; GARBARINO-PICO E; GIUSTO NM; GUIDO ME

Mendoza

Congreso; XLVIII Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB); 2012

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

Circadian clocks regulate biochemical processes including lipid metabolism and their disruption may lead to metabolic disorders such as obesity, diabetes, etc. We have previously shown that the 32P-phospholipid synthesis oscillates daily in synchronized fibroblasts; however, little is known about the temporal regulation of glycerophospholipid (GPL) synthesis. We found a circadian change in the incorporation of 3H-glycerol into total GPLs in arrested NIH3T3 cells synchronized with a 2 h-serum shock with lowest levels at 28 and 56 h. A daily variation was also seen in the activity of GPL-synthesizing and -remodeling enzymes phosphatidate phosphohydrolase 1 (PAP1) and lysophospholipid acyltransferases (LPLAT), respectively with distinct and opposite profiles. We further investigated the temporal regulation of phosphatidylcholine (PC) synthesis through the Kennedy pathway with Choline Kinase (ChoK) and CTP:phosphocholine cytidylyltranferase (CCT) as key enzymes. PC labeling exhibited a daily variation, and maximum levels were accompanied by a brief increase in CCT activity peaking at 6 and 35 h together with the oscillation of ChoK mRNA (á isoform) and activity. Our results demonstrate that synchronized fibroblasts undergo a temporal regulation in the synthesis and remodeling of GPLs and particularly of PC involving concerted changes in specific enzyme activities and/or mRNA expression.