Article

Characterization of peripheral circadian clocks in adipose tissues.

Stem Cell Laboratory, Louisiana State University, Pennington Biomedical Research Center, Baton Rouge, LA, USA.
Diabetes (impact factor: 8.29). 05/2006; 55(4):962-70. pp.962-70
Source: PubMed

ABSTRACT First described in the suprachiasmatic nucleus, circadian clocks have since been found in several peripheral tissues. Although obesity has been associated with dysregulated circadian expression profiles of leptin, adiponectin, and other fat-derived cytokines, there have been no comprehensive analyses of the circadian clock machinery in adipose depots. In this study, we show robust and coordinated expression of circadian oscillator genes (Npas2, Bmal1, Per1-3, and Cry1-2) and clock-controlled downstream genes (Rev-erb alpha, Rev-erb beta, Dbp, E4bp4, Stra13, and Id2) in murine brown, inguinal, and epididymal (BAT, iWAT, and eWAT) adipose tissues. These results correlated with respective gene expression in liver and the serum markers of circadian function. Through Affymetrix microarray analysis, we identified 650 genes that shared circadian expression profiles in BAT, iWAT, and liver. Furthermore, we have demonstrated that temporally restricted feeding causes a coordinated phase-shift in circadian expression of the major oscillator genes and their downstream targets in adipose tissues. The presence of circadian oscillator genes in fat has significant metabolic implications, and their characterization may have potential therapeutic relevance with respect to the pathogenesis and treatment of diseases such as obesity, type 2 diabetes, and the metabolic syndrome.

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Keywords

adipose depots
 
adipose tissues
 
Affymetrix microarray analysis
 
circadian clock machinery
 
circadian expression
 
circadian function
 
circadian oscillator genes
 
clock-controlled downstream genes
 
comprehensive analyses
 
dysregulated circadian expression profiles
 
fat-derived cytokines
 
major oscillator genes
 
metabolic syndrome
 
murine brown
 
peripheral tissues
 
respective gene expression
 
Rev-erb beta
 
shared circadian expression profiles
 
suprachiasmatic nucleus
 
type 2 diabetes