Carbon Monoxide Promotes VEGF Expression by Increasing HIF-1α Protein Level via Two Distinct Mechanisms, Translational Activation and Stabilization of HIF-1α Protein
Carbon Monoxide Promotes VEGF Expression by Increasing HIF-1α Protein Level via Two Distinct Mechanisms, Translational Activation and Stabilization of HIF-1α Protein
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DOI：
10.1074/jbc.m110.131284
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发表时间：
2010-10-15
影响因子：
4.8
通讯作者：
Kim, Young-Myeong
中科院分区：
文献类型：
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作者：
Choi, Yoon Kyung;Kim, Chun-Ki;Kim, Young-Myeong
一氧化碳（CO）在血管功能中起着重要作用。我们在此研究了CO调节HIF-1（缺氧诱导转录因子-1）依赖性血管内皮生长因子（VEGF）表达的分子机制，VEGF是一种重要的血管生成因子。我们发现CORM-2 （co -释放分子）刺激星形胶质细胞通过增加VEGF的表达和分泌来促进血管生成。CORM-2还诱导HO-1（血红氧合酶-1）表达和核HIF-1 α蛋白水平升高，但未改变其启动子活性和mRNA水平。用HIF-1 α siRNA和一种血红素加氧酶抑制剂抑制VEGF表达，说明CO通过上调HIF-1 α蛋白水平刺激VEGF表达，这与HO-1诱导有部分关联。CORM-2激活了翻译调节蛋白p70（S6k）和eIF-4E，并磷酸化了它们的上游信号介质Akt和ERK。这些翻译信号事件和HIF-1 α蛋白水平被磷脂酰肌醇3-激酶（PI3K）、MEK和mTOR抑制剂抑制，表明PI3K/Akt/mTOR和MEK/ERK通路参与了HIF-1 α的翻译增加。此外，CORM-2还通过抑制HIF-1 α的泛素化来提高其稳定性，而不改变脯氨酸羟化酶依赖的HIF-1 α降解途径。CORM-2增加HIF-1 α /HSP90 α相互作用，这是HIF-1 α稳定的原因，HSP90特异性抑制剂降低了这种相互作用、HIF-1 α蛋白水平和VEGF表达。此外，HSP90 α敲低抑制corm -2诱导的HIF-1 α和VEGF蛋白水平的升高。这些结果表明，CO通过两种不同的机制，即翻译刺激和HIF-1 α蛋白稳定，通过增加HIF-1 α蛋白水平来刺激VEGF的产生。
Carbon monoxide (CO) plays a significant role in vascular functions. We here examined the molecular mechanism by which CO regulates HIF-1 (hypoxia-inducible transcription factor-1)-dependent expression of vascular endothelial growth factor (VEGF), which is an important angiogenic factor. We found that astrocytes stimulated with CORM-2 (CO-releasing molecule) promoted angiogenesis by increasing VEGF expression and secretion. CORM-2 also induced HO-1 (hemeoxygenase-1) expression and increased nuclear HIF-1 alpha protein level, without altering its promoter activity and mRNA level. VEGF expression was inhibited by treatment with HIF-1 alpha siRNA and a hemeoxygenase inhibitor, indicating that CO stimulates VEGF expression via up-regulation of HIF-1 alpha protein level, which is partially associated with HO-1 induction. CORM-2 activated the translational regulatory proteins p70(S6k) and eIF-4E as well as phosphorylating their upstream signal mediators Akt and ERK. These translational signal events and HIF-1 alpha protein level were suppressed by inhibitors of phosphatidylinositol 3-kinase (PI3K), MEK, and mTOR, suggesting that the PI3K/Akt/mTOR and MEK/ERK pathways are involved in a translational increase in HIF-1 alpha. In addition, CORM-2 also increased stability of the HIF-1 alpha protein by suppressing its ubiquitination, without altering the proline hydroxylase-dependent HIF-1 alpha degradation pathway. CORM-2 increased HIF-1 alpha/HSP90 alpha interaction, which is responsible for HIF-1 alpha stabilization, and HSP90-specific inhibitors decreased this interaction, HIF-1 alpha protein level, and VEGF expression. Furthermore, HSP90 alpha knockdown suppressed CORM-2-induced increases in HIF-1 alpha and VEGF protein levels. These results suggest that CO stimulates VEGF production by increasing HIF-1 alpha protein level via two distinct mechanisms, translational stimulation and protein stabilization of HIF-1 alpha.