Gene promoter of apoptosis inhibitory protein IAP2: identification of enhancer elements and activation by severe hypoxia.
Inhibitors of apoptosis (IAPs) antagonize cell death and regulate the cell cycle. One mechanism controlling IAP expression is translation initiation through the internal ribosome entry sites. Alternatively, IAP expression can be regulated at the transcription level. We showed recently the activation of IAP2 transcription by severe hypoxia. To pursue this regulation, we have cloned the full-length cDNA of rat IAP2, and have isolated and analysed the promoter regions of this gene. The cDNA encodes a protein of 589 amino acids, exhibiting structural features of IAP. In rat tissues, a major IAP2 transcript of approximately 3.5 kb was detected. We subsequently isolated 3.3 kb of the proximal 5'-flanking regions of this gene, which showed significant promoter activity. Of interest, 5' sequential deletion of the promoter sequence identified an enhancer of approximately 200 bp. Deletion of cAMP-response-element-binding protein (CREB) sites in the enhancer sequence diminished its activity. Finally, the IAP2 gene promoter was activated significantly by severe hypoxia and not by CoCl(2) or desferrioxamine, pharmacological inducers of hypoxia-inducible factor-1. In conclusion, in this study we have cloned the full-length cDNA of rat IAP2, and for the first time we have isolated and analysed promoter sequences of this gene, leading to the identification of enhancer elements. Moreover, we have demonstrated activation of the gene promoter by severe hypoxia, a condition shown to induce IAP2. These findings provide a basis for further investigation of gene regulation of IAP2, a protein with multiple functions.
Dong
Zheng
Z
Department of Pathology, University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA. dong@uthscsa.edu
Nishiyama
Junichiro
J
Yi
Xiaolan
X
Venkatachalam
Manjeri A
MA
Denton
Michael
M
Gu
Sumin
S
Li
Senlin
S
Qiang
Mei
M
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D003035:Cobalt / Q000494:pharmacology; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D018076:DNA, Complementary; D003676:Deferoxamine / Q000494:pharmacology; D024202:Electrophoretic Mobility Shift Assay; D004742:Enhancer Elements, Genetic; D005786:Gene Expression Regulation; D006801:Humans; D000860:Hypoxia / Q000235:genetics*; D051034:Inhibitor of Apoptosis Proteins; D051379:Mice; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D016329:Sp1 Transcription Factor / Q000378:metabolism; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
D017362:Cyclic AMP Response Element-Binding Protein; D018076:DNA, Complementary; D051034:Inhibitor of Apoptosis Proteins; D012333:RNA, Messenger; D016329:Sp1 Transcription Factor; D014764:Viral Proteins; C086430:inhibitor of apoptosis, Nucleopolyhedrovirus; D003035:Cobalt; C018021:cobaltous chloride; D003676:Deferoxamine