Sonic hedgehog is a critical mediator of erythropoietin-induced cardiac protection in mice
Kazutaka Ueda, Hiroyuki Takano, Yuriko Niitsuma, Hiroshi Hasegawa, Raita Uchiyama, Toru Oka, Masaru Miyazaki, Haruaki Nakaya, Issei Komuro
Kazutaka Ueda, Hiroyuki Takano, Yuriko Niitsuma, Hiroshi Hasegawa, Raita Uchiyama, Toru Oka, Masaru Miyazaki, Haruaki Nakaya, Issei Komuro
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Research Article Cardiology

Sonic hedgehog is a critical mediator of erythropoietin-induced cardiac protection in mice

Abstract

Erythropoietin reportedly has beneficial effects on the heart after myocardial infarction, but the underlying mechanisms of these effects are unknown. We here demonstrate that sonic hedgehog is a critical mediator of erythropoietin-induced cardioprotection in mice. Treatment of mice with erythropoietin inhibited left ventricular remodeling and improved cardiac function after myocardial infarction, independent of erythropoiesis and the mobilization of bone marrow–derived cells. Erythropoietin prevented cardiomyocyte apoptosis and increased the number of capillaries and mature vessels in infarcted hearts by upregulating the expression of angiogenic cytokines such as VEGF and angiopoietin-1 in cardiomyocytes. Erythropoietin also increased the expression of sonic hedgehog in cardiomyocytes, and inhibition of sonic hedgehog signaling suppressed the erythropoietin-induced increase in angiogenic cytokine expression. Furthermore, the beneficial effects of erythropoietin on infarcted hearts were abolished by cardiomyocyte-specific deletion of sonic hedgehog. These results suggest that erythropoietin protects the heart after myocardial infarction by inducing angiogenesis through sonic hedgehog signaling.

Authors

Kazutaka Ueda, Hiroyuki Takano, Yuriko Niitsuma, Hiroshi Hasegawa, Raita Uchiyama, Toru Oka, Masaru Miyazaki, Haruaki Nakaya, Issei Komuro

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Figure 7

EPO upregulates expression levels of Shh.

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EPO upregulates expression levels of Shh. Western blotting of Shh in cul...
Western blotting of Shh in cultured neonatal rat cardiomyocytes and cardiac fibroblasts (A) and in the culture supernatants (B). Cells were treated with EPO (100 U/ml) or CEPO (100 U/ml) for 48 hours. Shh-N represents the aminoterminal domain of Shh, which is a biologically active form of Shh. (C) Immunocytochemical staining for Shh (red), α-sarcomeric actinin (green), and vimentin (blue). Cardiomyocytes and cardiac fibroblasts were cocultured with or without EPO for 48 hours. EPO induced the cytoplasmic accumulation of Shh in cardiomyocytes but not cardiac fibroblasts. Scale bars: 10 μm. (D) qRT-PCR analysis of Shh mRNA. Cardiomyocytes were treated with EPO for 24 hours (n = 5). *P < 0.05. (E) qRT-PCR analysis of Ptch-1, Gli-1, and Ang-1 mRNA. Cardiomyocytes were treated with rmShh (0.1 or 1.0 μg/ml) for 24 hours (n = 4). *P < 0.05; **P < 0.01 versus control. #P < 0.05; ##P < 0.01 versus rmShh and cyclopamine (5 μM) treatment. (F) Western blotting of VEGF. Cardiomyocytes were treated with rmShh (1.0 μg/ml) for 48 hours. Cyclopamine (cyclo) was administered 15 minutes before rmShh treatment. Representative Western blots and quantification of the bands are shown (n = 4).