Daily rhythms of glycerophospholipid synthesis in fibroblast cultures involve differential enzyme contributions

ACOSTA-RODRÍGUEZ VA; MARQUEZ S; SALVADOR GA; PASQUARÉ SJ; GORNÉ LD; GARBARINO PICO E; GIUSTO NM; GUIDO ME

JLR PAPERS IN PRESS

AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC

Lugar: Bethesda, Maryland; Año: 2013 vol. 54 p. 1798 - 1811

0022-2275

Circadian clocks regulate several biochemical processes including lipid metabolism and its disruption leads to severe metabolic disorders. Immortalized cell lines may act as circadian clocks displaying daily variations in [32P]-phospholipid labeling; however, the regulation of glycerophospholipid (GPL) synthesis remains unknown from a chronobiological perspective. In arrested NIH 3T3 cells synchronized with a 2 h-serum shock, we found significant temporal variations in: a) the labeling of total [3H]- GPLs, with lowest levels around 28 and 56 h, and b) the activity of GPL-synthesizing and -remodeling enzymes such as phosphatidate phosphohydrolase 1 (PAP-1) and lysophospholipid acyltransferases (LPLAT), respectively, with clear antiphase profiles. In addition, we investigated the temporal regulation of phosphatidylcholine (PC) biosynthesis. PC is mainly synthesized through the Kennedy pathway being Choline Kinase (ChoK) and CTP: phosphocholine cytidylyltranferase (CCT), key regulatory enzymes. PC labeling exhibited a significant daily variation with the lowest levels every ~28 h, variations that were accompanied by brief increases in CCT activity and the oscillation in ChoK mRNA expression and activity. Results demonstrate that synchronized fibroblasts are subject to complex levels of metabolic regulation exhibiting temporal variations in the synthesis of net GPLs and particularly of PC with concerted changes in specific enzyme expression and/or activities.