The metabolism of phospholipids oscillates rhythmically in cultures of fibroblasts and is regulated by the clock protein PERIOD 1.
The mammalian circadian timing system is composed of countless cell oscillators distributed throughout the body and central pacemakers regulating temporal physiology and behavior. Peripheral clocks display circadian rhythms in gene expression both in vivo and in culture. We examined the biosynthesis of phospholipids as well as the expression of the clock gene period 1 (Per1) and its potential involvement in the regulation of the phospholipid metabolism in cultured quiescent NIH 3T3 cells synchronized by a 2 h serum shock. A 30 min pulse of radiolabeled precursor was given at phases ranging from 0.5 to 62 h after serum treatment. We observed a daily rhythm in the phospholipid labeling that persisted at least for two cycles, with levels significantly decreasing 29 and 58 h after treatment. Per1 expression exhibited a rapid and transient induction and a daily rhythmicity in antiphase to the lipid labeling. After Per1 expression knockdown, the rhythm of phospholipid labeling was lost. Furthermore, in cultures of CLOCK mutant fibroblasts--cells with a clock mechanism impairment--PER1 was equally expressed at all times examined and the phospholipid labeling did not oscillate. The results demonstrate that the biosynthesis of phospholipids oscillates daily in cultured fibroblasts by an endogenous clock mechanism involving Per1 expression.
Marquez
Sebastian
S
CIQUIBIC, Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba, Argentina.
Crespo
Pilar
P
Carlini
Valeria
V
Garbarino-Pico
Eduardo
E
Baler
Ruben
R
Caputto
Beatriz L
BL
Guido
Mario E
ME
D016475:3T3 Cells / Q000378:metabolism; D000818:Animals; D001790:Blood Physiological Phenomena; D056926:CLOCK Proteins; D018797:Cell Cycle Proteins; D002478:Cells, Cultured / Q000187:drug effects; D002940:Circadian Rhythm; D003470:Culture Media / Q000494:pharmacology; D005347:Fibroblasts / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D005990:Glycerol / Q000378:metabolism; D006736:Horses; D051379:Mice; D008810:Mice, Inbred C57BL; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D056950:Period Circadian Proteins; D010710:Phosphates / Q000378:metabolism; D010743:Phospholipids / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000096:biosynthesis; D015534:Trans-Activators / Q000235:genetics / Q000502:physiology
D018797:Cell Cycle Proteins; D003470:Culture Media; D009687:Nuclear Proteins; D016376:Oligonucleotides, Antisense; C539023:Per1 protein, mouse; D056950:Period Circadian Proteins; D010710:Phosphates; D010743:Phospholipids; D012333:RNA, Messenger; D015534:Trans-Activators; D056926:CLOCK Proteins; C538944:Clock protein, mouse; D005990:Glycerol