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Mild hypoxia-induced cardiomyocyte hypertrophy via up-regulation of HIF-1α-mediated TRPC signalling.

ABSTRACT: Hypoxia-inducible factor-1 alpha (HIF-1α) is a central transcriptional regulator of hypoxic response. The present study was designed to investigate the role of HIF-1α in mild hypoxia-induced cardiomyocytes hypertrophy and its underlying mechanism. Mild hypoxia (MH, 10% O(2)) caused hypertrophy in cultured neonatal rat cardiac myocytes, which was accompanied with increase of HIF-1α mRNA and accumulation of HIF-1α protein in nuclei. Transient receptor potential canonical (TRPC) channels including TRPC3 and TRPC6, except for TRPC1, were increased, and Ca(2+)-calcineurin signals were also enhanced in a time-dependent manner under MH condition. MH-induced cardiomyocytes hypertrophy, TRPC up-regulation and enhanced Ca(2+)-calcineurin signals were inhibited by an HIF-1α specific blocker, SC205346 (30 μM), whereas promoted by HIF-1α overexpression. Electrophysiological voltage-clamp demonstrated that DAG analogue, OAG (30 μM), induced TRPC current by as much as 170% in neonatal rat cardiomyocytes overexpressing HIF-1α compared to negative control. These results implicate that HIF-1α plays a key role in development of cardiac hypertrophy in responses to hypoxic stress. Its mechanism is associated with up-regulating TRPC3, TRPC6 expression, activating TRPC current and subsequently leading to enhanced Ca(2+)-calcineurin signals.

SUBMITTER: Chu W

PROVIDER: S-EPMC3822973 | biostudies-literature | 2012 Sep

REPOSITORIES: biostudies-literature

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Mild hypoxia-induced cardiomyocyte hypertrophy via up-regulation of HIF-1α-mediated TRPC signalling.

Chu Wenfeng W Wan Lin L Zhao Dan D Qu Xuefeng X Cai Fulai F Huo Rong R Wang Ning N Zhu Jiuxin J Zhang Chun C Zheng Fangfang F Cai Ruijun R Dong Deli D Lu Yanjie Y Yang Baofeng B

Journal of cellular and molecular medicine 20120901 9

Hypoxia-inducible factor-1 alpha (HIF-1α) is a central transcriptional regulator of hypoxic response. The present study was designed to investigate the role of HIF-1α in mild hypoxia-induced cardiomyocytes hypertrophy and its underlying mechanism. Mild hypoxia (MH, 10% O(2)) caused hypertrophy in cultured neonatal rat cardiac myocytes, which was accompanied with increase of HIF-1α mRNA and accumulation of HIF-1α protein in nuclei. Transient receptor potential canonical (TRPC) channels including ...[more]

PMID: 22129453

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Project description:Background Few reports have addressed the mechanism by which microRNA miR-10b-5p regulates post-myocardial infarction (post-MI) cardiomyocyte apoptosis under hypoxic conditions. Methods and Results C57BL/6 mice underwent surgical ligation of the left anterior descending artery to create an MI or ischemia/reperfusion animal model. The expression of miR-10b-5p, PTEN (phosphatase and tensin homolog), and HIF-1α (hypoxia-inducible factor 1α) was detected in infarct border zone tissues at various time points. After precordial injections of the negative control or miR-10b-5p, overexpression lentiviruses were made in the areas surrounding the MI sites at 1 week, and myocardial infarct size, cardiac function, and cardiomyocyte apoptosis were examined. A miR-10b-5p mimic was transfected into primary mouse cardiomyocytes to analyze its effects on cardiomyocyte apoptosis and PTEN expression. Meanwhile, PTEN as a target of miR-10b-5p was verified via luciferase reporter gene assays. Cotransfection of miR-10b-5 and PTEN verified the relationship between miR-10b-5 and PTEN. Under hypoxic stress, the expression of HIF-1α and miR-10b-5p was examined. The results showed that miR-10b-5p expression was markedly reduced in the infarct border zone. Overexpression of miR-10b-5p in the murine model of MI significantly reduced MI size, improved cardiac function, and inhibited apoptosis. Overexpression of miR-10b-5p in vitro antagonized hypoxia-induced cardiomyocyte apoptosis and specifically inhibited the expression of the apoptosis-related gene PTEN, but overexpression of PTEN weakened these effects. We also found that hypoxia-induced accumulation of HIF-1α resulted in decreased expression of miR-10b-5p. Interfering with the activation of the HIF-1α signaling pathway promoted Pri-miR-10b and miR-10b-5p expression and inhibited PTEN expression. Conclusions MicroRNA miR-10b-5p antagonizes hypoxia-induced cardiomyocyte apoptosis, indicating that miR-10b-5p may serve as a potential future clinical target for the treatment of MI.

Dataset Information

Mild hypoxia-induced cardiomyocyte hypertrophy via up-regulation of HIF-1α-mediated TRPC signalling.

Publications

Mild hypoxia-induced cardiomyocyte hypertrophy via up-regulation of HIF-1α-mediated TRPC signalling.

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