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Arch Med Sci. 2011 Dec 31;7(6):933-40. doi: 10.5114/aoms.2011.26603. Epub 2011 Dec 30.

Obesity alters the expression profile of clock genes in peripheral blood mononuclear cells.

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Division of Nephrology, Hypertension and Endocrinology, Department of Medicine, Nihon University School of Medicine, Tokyo, Japan.



The aim of this study was to investigate the association between the variation in expression profile of clock genes and obesity using peripheral blood mononuclear (PMN) cells.


The subjects comprised 10 obese patients and 10 healthy volunteers. Blood was collected at different time-points during the day and levels of blood sugar, IRI, adiponectin and leptin were determined. Peripheral blood mononuclear cells were sampled, and expression levels of brain and muscle Arnt-like protein-1 (BMAL1), Period (PER)1, PER2, Cryptochrome (CRY)1, CRY2, and REV-ERBĪ± mRNA were quantified.


During the day, the expression levels of BMAL1, CRY1, CRY2 and PER2 genes in PMN cells of the obese group were all significantly higher compared to those in the non-obese group. In addition, expression of BMAL1, CRY1, CRY2 and PER2 genes in PMN cells increased between 12:00 and 21:00 in the obese group. In PMN cells of both groups, PER1 gene expression showed a bimodal pattern, with high expression at 9:00 and 18:00.


Differences were observed in the expression profile variation of clock genes between the obese and non-obese groups. This study reveals the differences in clock gene expression profiles between obese and non-obese subjects, with evidence for two distinct chronotypes, and suggests a contribution of these chronotypes to fat accumulation in humans.


Bmal1; Per1; biological clock; circadian rhythm

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