Microtubules Regulate Hypoxia-inducible Factor-1α Protein Trafficking and Activity IMPLICATIONS FOR TAXANE THERAPY
Microtubules Regulate Hypoxia-inducible Factor-1α Protein Trafficking and Activity IMPLICATIONS FOR TAXANE THERAPY
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DOI：
10.1074/jbc.m112.345587
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发表时间：
2012-04-06
影响因子：
4.8
通讯作者：
Giannakakou, Paraskevi
中科院分区：
文献类型：
--
作者：
Carbonaro, Marisa;Escuin, Daniel;Giannakakou, Paraskevi
微管细胞骨架的破坏通过抑制缺氧诱导因子（HIF 1 α）途径损害肿瘤血管生成。然而，连接微管破坏与HIF-1 α失活的信号级联尚未阐明。在这里，我们表明，微管靶向药物（MTD）治疗损害HIF-1 α蛋白核转位，显着下调HIF转录活性。我们提供了强有力的证据表明，HIF-1 α蛋白与聚合的微管和交通到细胞核，与动力蛋白马达蛋白的援助。总之，这些数据表明，微管是至关重要的参与核运输和转录活性的HIF-1 α。我们还表明，微管细胞骨架和HIF-1 α调节之间的联系在肾细胞癌（RCC）中丢失，其中HIF-1 α由于von Hippel Lindau（VHL）肿瘤抑制蛋白的突变而过表达。具体地说，我们发现MTD处理RCC细胞不会损害HIF-1 α的核积累或转录活性，并且对HIF-1 α的多核糖体结合特征没有影响。有趣的是，我们发现HIF-1 α蛋白在RCC中不结合微管。此外，VHL功能的恢复未能恢复MTD抑制HIF-1 α的能力，表明VHL对该表型没有贡献。总之，这些结果表明，HIF-1 α的调节是微管独立的，并可能有助于RCC的化疗耐药性质。鉴于HIF-1 α在肿瘤生物学中的重要性，以及MTD在临床肿瘤学中的广泛应用，进一步了解微管依赖性HIF-1 α调节以及RCC中缺乏这种调节是至关重要的。
Disruption of the microtubule cytoskeleton impairs tumor angiogenesis by inhibiting the hypoxia-inducible factor (HIF1 alpha) pathway. However, the signaling cascade linking microtubule disruption to HIF-1 alpha inactivation has not been elucidated. Here, we show that microtubule-targeting drug (MTD) treatment impaired HIF-1 alpha protein nuclear translocation, which significantly down-regulated HIF transcriptional activity. We provide strong evidence that HIF-1 alpha protein associates with polymerized microtubules and traffics to the nucleus, with the aid of the dynein motor protein. Together, these data suggest that microtubules are critically involved in the nuclear trafficking and transcriptional activity of HIF-1 alpha. We also show that the connection between the microtubule cytoskeleton and HIF-1 alpha regulation is lost in renal cell carcinoma (RCC), where HIF-1 alpha is overexpressed because of mutations in the von Hippel Lindau (VHL) tumor suppressor protein. Specifically, we show that MTD treatment of RCC cells did not impair HIF-1 alpha nuclear accumulation or transcriptional activity, and had no effect on the polysome association profile of HIF-1 alpha. Interestingly, we found that HIF-1 alpha protein did not bind microtubules in RCC. Moreover, restoration of VHL function failed to restore the ability of MTDs to inhibit HIF-1 alpha, suggesting that VHL does not contribute to this phenotype. Together, these results suggest that HIF-1 alpha regulation is microtubule-independent, and likely contributes to the chemoresistant nature of RCCs. Further understanding of the microtubule-dependent HIF-1 alpha regulation, and lack thereof in RCC, is essential given the impor-tance of HIF-1 alpha in tumor biology, and the widespread use of MTDs in clinical oncology.