Kelch-like 20 up-regulates the expression of hypoxia-inducible factor-2α through hypoxia- and von Hippel-Lindau tumor suppressor protein-independent regulatory mechanisms
Kelch-like 20 up-regulates the expression of hypoxia-inducible factor-2α through hypoxia- and von Hippel-Lindau tumor suppressor protein-independent regulatory mechanisms
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DOI：
10.1016/j.bbrc.2011.08.058
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发表时间：
2011-09-23
影响因子：
3.1
通讯作者：
Nakano, Yoshihisa
中科院分区：
文献类型：
--
作者：
Higashimura, Yasuki;Terai, Takashi;Nakano, Yoshihisa
尽管它们的结构相似，但缺氧诱导因子（HIF）-1 α和HIF-2 α具有不同的功能特性，并表现出不同的时空表达模式，这表明这两种蛋白质的表达受不同机制的调节。为了阐明HIF-2 α特异性调控机制，我们在酵母双杂交系统中筛选HIF-2 α相关蛋白，并鉴定了kelch样20（KLHI 20）。HIF-2 α与KLHL 20相互作用，而HIF-1 α与KLHL 20不相互作用。siRNA介导的KLHL 20敲低降低了HIF-2 α蛋白，但没有HIF-2 α mRNA或HIF-1 α蛋白。KLHL 20的消耗降低了缺氧诱导的HIF活性，并因此导致HIF-2 α应答基因如VEGF和CITED 2的表达水平降低。相反，KLHL 20的过表达增加了O（2）敏感野生型和O（2）不敏感突变型HIF-2 α的表达水平和转录活性。KLHL 20 siRNA还抑制von Hippel-Lindau肿瘤抑制蛋白（pVHL）缺陷型786-O细胞中的HIF-2活性。这些结果表明，KLHL 20是一个新的球员，调节HIF-2 α蛋白的表达，通过机制独立于缺氧和pVHL。(C)2011 Elsevier Inc. All rights reserved.
Despite their structural similarity, hypoxia-inducible factor (HIF)-1 alpha and HIF-2 alpha have distinct functional properties and exhibit distinct spatiotemporal expression patterns, suggesting that the expressions of the two proteins are regulated by different mechanisms. To clarify the HIF-2 alpha-specific regulatory mechanism, we screened HIF-2 alpha-associated proteins in a yeast two-hybrid system and identified kelch-like 20 (KLHI20). HIF-2 alpha, but not HIF-1 alpha, interacted with KLHL20. siRNA-mediated knockdown of KLHL20 decreased HIF-2 alpha protein, but not HIF-2 alpha mRNA or HIF-1 alpha protein. Depletion of KLHL20 decreased hypoxia-induced HIF activity, and consequently resulted in decreased expression levels of HIF-2 alpha-responsive genes such as VEGF and CITED2. In contrast, overexpression of KLHL20 increased the expression levels and transcriptional activities of the O(2)-sensitive wild-type and O(2)-insensitive mutant forms of HIF-2 alpha. KLHL20 siRNA also inhibited HIF-2 activity in von Hippel-Lindau tumor suppressor protein (pVHL)-deficient 786-O cells. These results indicate that KLHL20 is a novel player that regulates HIF-2 alpha protein expression through mechanisms independent of hypoxia and pVHL. (C) 2011 Elsevier Inc. All rights reserved.