Members of the cell death-inducing DFF45-like effector (CIDE) gene family have 
been shown to regulate lipid metabolism. In this article, we report that the 
third member of the human CIDE family, CIDEC, is down-regulated in response to a 
reduced caloric intake. The down-regulation was demonstrated by microarray and 
real-time polymerase chain reaction analysis of subcutaneous adipose tissue in 2 
independent studies on obese patients undergoing treatment with a very low 
calorie diet. By analysis of CIDEC expression in 65 human tissues, we conclude 
that human CIDEC is predominantly expressed in subcutaneous adipocytes. 
Together, these observations led us to investigate the effect of decreased CIDEC 
expression in cultured 3T3-L1 adipocytes. Small interfering RNA-mediated 
knockdown of CIDEC resulted in an increased basal release of nonesterified fatty 
acids, decreased responsiveness to adrenergic stimulation of lipolysis, and 
increased oxidation of endogenous fatty acids. Thus, we suggest that CIDEC is a 
regulator of adipocyte lipid metabolism and may be important for the adipocyte 
to adapt to changes in energy availability.