Melanoma antigen-11 inhibits the hypoxia-inducible factor prolyl hydroxylase 2 and activates hypoxic response.
Melanoma antigen-11 inhibits the hypoxia-inducible factor prolyl hydroxylase 2 and activates hypoxic response.
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DOI：
10.1158/0008-5472.can-08-0811
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发表时间：
2009-01-15
期刊：
影响因子：
11.2
通讯作者：
Niederhuber, John
中科院分区：
文献类型：
--
作者：
Aprelikova, Olga;Pandolfi, Silvia;Tackett, Sean;Ferreira, Mark;Salnikow, Konstantin;Ward, Yvona;Risinger, John I.;Barrett, J. Carl;Niederhuber, John
缺氧诱导因子（HIF）的激活，负责肿瘤血管生成和糖酵解开关，是由减少氧可用性调节。正常情况下，HIF-α蛋白维持在低水平，由HIF脯氨酰羟化酶（PHD）进行的位点特异性羟基化和随后通过von Hippel-Lindau（VHL）泛素连接酶进行的蛋白酶体降解控制。利用酵母双杂交筛选，我们鉴定了法师-11肿瘤-睾丸抗原和主要的HIF-α羟化酶PHD 2之间的相互作用。在常氧和低氧条件下，通过下拉测定、免疫共沉淀和共定位证实了相互作用。此外，还发现法师-11最接近的同源物法师-9与PHD 2相互作用。法师-11抑制PHD活性而不影响蛋白水平。这种抑制伴随着异位或内源性HIF-1α蛋白的稳定。siRNA敲低法师-11可降低HIF-1α及其靶基因的缺氧诱导作用。通过法师-11抑制PHD并随后激活缺氧诱导因子是一种新的肿瘤相关HIF调节机制。这一发现为肿瘤中法师表达的意义提供了新的见解，并可能为治疗干预提供有价值的工具，因为法师基因家族在癌症中而不是在正常组织中的有限表达。
Activation of hypoxia-inducible factors (HIFs), responsible for tumor angiogenesis and glycolytic switch, is regulated by reduced oxygen availability. Normally, HIF-α proteins are maintained at low levels, controlled by site-specific hydroxylation carried out by HIF prolyl hydroxylases (PHDs), and subsequent proteasomal degradation via the von Hippel-Lindau (VHL) ubiquitin ligase. Using a yeast-two hybrid screen, we identified an interaction between MAGE-11 cancer-testis antigen and the major HIF-α hydroxylating enzyme PHD2. The interaction was confirmed by pull-down assay, co-immunoprecipitation and co-localization in both normoxic and hypoxic conditions. Furthermore, MAGE-9, the closest homolog of MAGE-11, was also found to interact with PHD2. MAGE-11 inhibited PHD activity without affecting protein levels. This inhibition was accompanied by stabilization of ectopic or endogenous HIF-1α protein. Knock-down of MAGE-11 by siRNA results in decreased hypoxic induction of HIF-1α and its target genes. Inhibition of PHD by MAGE-11 and following activation of hypoxia-inducible factors is a novel tumor associated HIF regulatory mechanism. This finding provides new insights into the significance of MAGE expression in tumors and may provide valuable tools for therapeutic intervention because of the restricted expression of the MAGE gene family in cancers but not in normal tissues.