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

Navin Viswakarma,Songtao Yu,Swati Naik,Papreddy Kashireddy,Kojiro Matsumoto,Joy Sarkar,Sailesh Surapureddi,Yuzhi Jia,M Sambasiva Rao,Janardan K Reddy

doi:10.1074/jbc.m701983200

Abstract

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 ligands Wy-14,643 and ciprofibrate increase the Cidea mRNA level in a PPARalpha-dependent manner, whereas Cidea induction in liver by PPARgamma overexpression is PPARalpha 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 PPARalpha and PPARgamma 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 PPARalpha and -gamma. We conclude that Cidea is a novel target gene for both PPARalpha 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 PPARalpha and -gamma agonists suggests a possible role for Cidea in energy metabolism and a less likely role in hepatocyte apoptosis.

Highlights

Namely peroxisome proliferator-activated receptor (PPAR)␣(NR1C1), PPAR␤/␦(NR1C2), and PPAR␥(NR1C3) [1,2,3]
We show that a Cidea gene promoter contains a functional peroxisome proliferator response elements (PPREs) that is responsive to both these PPAR isotypes
To determine whether the Cidea gene contains a PPRE(s), which may be responsive to PPAR␣- and -␥

Summary

EXPERIMENTAL PROCEDURES

Mice and Treatments—Wild-type (C57BL/6J) and PPAR␣Ϫ/Ϫ mice (3– 4-month old) were kept on a 12-h light-dark cycle [23]. To assess whether Cidea induction in liver leads to increased apoptosis, groups of 5– 8 wild-type mice were fed control diet or diet containing Wy-14,643 for 4 days and 4 weeks, hematoxylin- and eosin-stained or TUNEL-stained (Roche Applied Science) liver sections were analyzed. Amplified cDNA was cloned into pCR4-TOPO vector (Invitrogen), sequenced, radiolabeled, and used as a probe. The dA-tailed cDNA was PCR amplified using an oligo(dT)-anchor primer and another Cidea-specific primer Cide-A (RACE)-2, which anneals 79 bp downstream of the Cidea translational start site. The amplified products were purified using a High Pure PCR product purification kit (Roche Applied Science) and cloned into the pCR4-TOPO (Invitrogen) and sequenced to assign transcription start site. The DNA fragment (ϳ3 kb), containing the Cidea promoter was amplified using the Expand High Fidelity PCR system (Roche Applied Science) and designated pL-Cid. Luciferase activity of each construct was compared with that of the promoterless pGL3-Basic vector

Electrophoretic Mobility Shift

Cidea mRNA Is Induced in Mouse

Cidea inductive effects in mouse liver following treatment with

EMSA primers

DISCUSSION