The CIDE genes might serve as novel targets for therapeutic intervention of obesity

Distribution and quantitative analysis of CIDEa and CIDEc in broiler chickens: accounting for differential fat deposition between strains

1. Differences in the expression of CIDEa and CIDEc in 20 different tissues were examined. Both CIDEa and CIDEc mRNA transcripts were predominantly but variably expressed in white adipose tissue (WAT) but were also expressed at moderate levels in the kidney and liver and at lower levels in the ovary. Interestingly, among WAT types, both CIDEa and CIDEc were expressed at the lowest levels in heart coronary WAT. 2. To better understand the roles of CIDEa and CIDEc in the fat deposition of broiler chickens, the differences in lipid droplet (LD) size and mRNA levels of CIDEa and CIDEc between lean-type and fat-type broiler chicken lines were studied. LD sizes were larger in fat-type broiler lines, and CIDEa and CIDEc mRNA levels in white adipose, kidney and liver tissues were significantly higher in fat-type broiler lines than in their lean counterparts. 3. Developmental expression patterns of CIDEa and CIDEc mRNA were analysed in different tissue types (WAT, liver and kidney) in Arbor Acres broiler chickens, and CIDEa and CIDEc mRNA expression levels increased during sequential developmental stages, achieving peak expression levels at week 6. 4. These observations suggest that the functions of CIDEa and CIDEc reflect inherent characteristics of lipid metabolism that contribute to the differences in fat deposition between strains. The results in this study contribute to a more robust understanding of the tissue distribution and expression patterns of CIDEa and CIDEc mRNA and facilitate further research concerning the molecular mechanism underlying fat deposition in broiler chickens.

Molecular cloning, genomic organization, chromosome mapping, tissues expression pattern and identification of a novel splicing variant of porcine CIDEb gene

Cell death-inducing DNA fragmentation factor-α-like effector b (CIDEb) is a member of the CIDE family of apoptosis-inducing factors, CIDEa and CIDEc have been reported to be Lipid droplets (LDs)-associated proteins that promote atypical LD fusion in adipocytes, and responsible for liver steatosis under fasting and obese conditions, whereas CIDEb promotes lipid storage under normal diet conditions [1], and promotes the formation of triacylglyceride-enriched VLDL particles in hepatocytes [2]. Here, we report the gene cloning, chromosome mapping, tissue distribution, genetic expression analysis, and identification of a novel splicing variant of the porcine CIDEb gene. Sequence analysis shows that the open reading frame of the normal porcine CIDEb isoform covers 660bp and encodes a 219-amino acid polypeptide, whereas its alternative splicing variant encodes a 142-amino acid polypeptide truncated at the fourth exon and comprised of the CIDE-N domain and part of the CIDE-C domain. The deduced amino acid sequence of normal porcine CIDEb shows an 85.8% similarity to the human protein and 80.0% to the mouse protein. The CIDEb genomic sequence spans approximately 6KB comprised of five exons and four introns. Radiation hybrid mapping demonstrated that porcine CIDEb is located at chromosome 7q21 and at a distance of 57cR from the most significantly linked marker, S0334, regions that are syntenic with the corresponding region in the human genome. Tissue expression analysis indicated that normal CIDEb mRNA is ubiquitously expressed in many porcine tissues. It was highly expressed in white adipose tissue and was observed at relatively high levels in the liver, lung, small intestine, lymphatic tissue and brain. The normal version of CIDEb was the predominant form in all tested tissues, whereas the splicing variant was expressed at low levels in all examined tissues except the lymphatic tissue. Furthermore, genetic expression analysis indicated that CIDEb mRNA levels were significantly higher in the white adipose tissue of lean pigs than their obese counterparts, in contrast to porcine CIDEa and CIDEc [3]. We therefore speculate that CIDEb may play a contrary role to the other CIDEs. The basic molecular information we provide here will be useful for further investigations of the physiological function of the gene, which will be helpful in better understanding the role of the CIDE family in lipid metabolism in pig models.

Molecular cloning, chromosomal location and expression pattern of porcine CIDEa and CIDEc

Cell death-inducing DFF45-like effectors a and c (CIDEa and CIDEc) are two members of the novel CIDE family of apoptosis-inducing factors. Except as pro-apoptotic proteins, it has been reported that CIDEa and CIDEc could be involved in lipid or fat metabolism. Here we first reported the cDNA cloning, chromosome mapping and expression analysis of CIDEa and CIDEc in pigs. Sequence analysis showed that porcine CIDEa contains an open reading frame of 660 bp, which encodes 219 amino acids, and CIDEc contains a coding region of 717 bp that encodes 238 amino acids. The deduced amino acid sequence of porcine CIDEa and CIDEc shows high similarities to their corresponding human and mouse homologues. Radiation hybrid mapping demonstrated that porcine CIDEa and CIDEc are located at chromosome 6q21-26 and 13q31 respectively, syntenic with the loci of their corresponding homologues on human chromosomes. Tissue distribution analysis indicated that porcine CIDEa and CIDEc mRNAs are co-expressed in various tissues. Both of them were highly expressed in white adipose tissue, and CIDEc mRNA was also expressed at relatively high level in porcine small intestine, lymph and brain. Furthermore, CIDEa and CIDEc mRNA level in white adipose tissues and liver were significantly higher in obese pigs than in their lean counterparts. Our studies provide basic molecular information useful for the further investigation on the function of the two genes, which will be helpful in better understanding of the roles of CIDEs in lipid metabolism.

Transcriptional activation of Cidec by PPARgamma2 in adipocyte

Cidec is a lipid droplet-associated protein, which inhibits lipolysis, leading to the accumulation of triglycerides in adipocytes. However, the transcriptional regulation of Cidec in adipocyte remains unknown. In the present study we investigated that the mouse Cidec transcript is regulated by PPARgamma2. After the differentiation of adipocyte, the expression pattern of Cidec was similar to that of PPARgamma2. In the presence of a PPARgamma agonist, the level of Cidec mRNA was highly increased. In addition, putative PPRE sites were identified in the Cidec promoter. By chromatin immunoprecipitation assay and reporter assay, we observed the binding of PPARgamma2 to the promoter of Cidec. Gel shift assay and the mutagenesis study were showed that the -219/-207 region of the Cidec promoter could function as a PPRE of the Cidec promoter. These results suggest that PPARgamma2 is required for the transcriptional activity of Cidec during adipogenesis, which could be contributed to understand the molecular mechanism of lipid droplet formation in adipocytes.