Endothelial PAS domain protein 1 (EPAS1) induces adrenomedullin gene expression in cardiac myocytes: role of EPAS1 in an inflammatory response in cardiac myocytes.
Endothelial PAS domain protein 1 (EPAS1) has been identified as a member of the basic helix-loop-helix (bHLH)-PAS protein family, and plays a critical role in the regulation of hypoxia inducible genes. It remains unknown whether physiological stimuli other than hypoxia modulate EPAS1 expression. This study examined the inducible expression of EPAS1 by various cytokines and growth factors, and determined the target gene for EPAS1 in cardiac myocytes. In cultured cardiac myocytes, interleukin-1beta (IL-1beta) but not tumor necrosis factor alpha markedly increased the EPAS1 mRNA and protein levels in a time- and dose-dependent manner, whereas hypoxia increases the expression of EPAS1 protein but not its mRNA. Such an induction of EPAS1 by IL-1beta was efficiently inhibited by the pretreatment of the cells with Src kinase inhibitors, such as herbimycin A and PP1. The expression of adrenomedullin (AM) mRNA, which is also upregulated by IL-1beta, was dramatically increased in cardiac myocytes transduced with adenovirus expressing EPAS1. Transient transfection assays using the site-specific mutation of the AM promoter showed that EPAS1 overexpression increases the transcriptional activity through a sequence similar to the consensus HRE (hypoxia responsive element). These results suggest that IL-1beta induces the EPAS1 at the transcriptional level, which in turn activates the AM gene. Since IL-1beta has been implicated in the pathogenesis of heart failure and AM can ameliorate the cardiac function, our results suggest that EPAS1 plays a role in the adaptation of the cardiac myocytes during heart failure as well as in the regulation of gene expression by hypoxia.
Tanaka
Toru
T
Second Department of Internal Medicine, Gunma University School of Medicine, 3-39-15, Showa-machi, Maebashi, Gunma, 371-8511, Japan.
Akiyama
Hideo
H
Kanai
Hiroyoshi
H
Sato
Mahito
M
Takeda
Shinichi
S
Sekiguchi
Kenichi
K
Yokoyama
Tomoyuki
T
Kurabayashi
Masahiko
M
D053607:Adrenomedullin; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D005786:Gene Expression Regulation; D018014:Gene Transfer Techniques; D006333:Heart Failure / Q000378:metabolism; D007249:Inflammation / Q000378:metabolism; D007375:Interleukin-1 / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000378:metabolism*; D010455:Peptides / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D015534:Trans-Activators / Q000378:metabolism*; D015854:Up-Regulation; D019061:src-Family Kinases / Q000378:metabolism; D000099162:Endothelial PAS Domain-Containing Protein 1
D053607:Adrenomedullin; D051792:Basic Helix-Loop-Helix Proteins; D007375:Interleukin-1; D010455:Peptides; D012333:RNA, Messenger; D015534:Trans-Activators; D019061:src-Family Kinases; D000099162:Endothelial PAS Domain-Containing Protein 1