Transcriptional regulation of Cidea, mitochondrial cell death-inducing DNA fragmentation factor α-like effector A, in mouse liver by peroxisome proliferator-activated receptor α and γ

Cidea ( cell death-inducing DNA fragmentation factor alpha-like effector A), a member of a novel family of proapoptotic proteins, is expressed abundantly in the brown adipose tissue of the mouse. Although Cidea mRNA is not detectable in the mouse liver, we now show that peroxisome proliferator-activated receptor ( PPAR) alpha ligandsWy-14,643 and ciprofibrate increase the Cidea mRNA level in a PPAR alpha-dependent manner, whereas Cidea induction in liver by PPAR gamma overexpression is PPAR alpha independent. Increase in Cidea mRNA content in liver did not alter the expression of uncoupling protein 1 (Ucp1) gene, which regulates thermogenesis, lipolysis, and conservation of energy. Although Cidea is considered to be a proapoptotic factor, Cidea induction in liver did not result in increased apoptosis. To elucidate the mechanism by which PPAR alpha and PPAR gamma regulate Cidea gene expression in the liver, we analyzed the promoter region of the Cidea gene. Three putative peroxisome proliferator response elements (PPREs) are found in the Cidea gene promoter. Transactivation, gel-shift, and chromatin immunoprecipitation assays indicated that the proximal PPRE in Cidea gene (Cidea-PPRE1 at - 680/ - 668) is functional for both PPAR alpha and -gamma. We conclude that Cidea is a novel target gene for both PPAR alpha and -gamma in the liver where these two transcription factors utilize the same PPRE region for dual regulation. The induction of Cidea in liver with these PPAR alpha and -gamma agonists suggests a possible role for Cidea in energy metabolism and a less likely role in hepatocyte apoptosis.