Translational control of collagen prolyl 4-hydroxylase-α(I) gene expression under hypoxia
Translational control of collagen prolyl 4-hydroxylase-α(I) gene expression under hypoxia
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DOI：
10.1074/jbc.m604939200
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发表时间：
2006-09-08
影响因子：
4.8
通讯作者：
Thiele, Bernd J.
中科院分区：
文献类型：
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作者：
Faehling, Michael;Mrowka, Ralf;Thiele, Bernd J.
缺氧是一种促纤维化刺激，其与增强的胶原蛋白合成以及增强的胶原蛋白脯氨酰4-羟化酶（C-P4 H）活性相关。C-P4 H活性主要由α C-P4 H亚基的调节表达控制。在这项研究中，我们证明了在长期缺氧（36小时，1%的氧气）下，人HT 1080成纤维细胞中C-P4 H-α（I）蛋白的合成增加是在翻译水平上控制的。这是由RNA结合蛋白核仁素（类似于64 kDa形式）在themRNA的5 '和3'非翻译区（UTR）的相互作用介导的。5 '/3'-UTR依赖性机制使C-P4 H-α（I）表达率升高2.3倍，并参与长期缺氧下蛋白水平升高5.3倍。核仁素在5 '-UTR处的相互作用直接发生并且取决于富含AU的元件的存在。类似于64 kDa核仁素/ RNA相互作用研究的统计学评价揭示了一个核心结合序列，对应于UAAAUC或AAAUCU。在3 '-UTR处，核仁素通过蛋白质/蛋白质相互作用间接组装，并借助于另一种3'-UTR结合蛋白，可能是膜联蛋白A2。在低氧条件下，类似于64-kDa核仁素的蛋白质水平的增加可以归因于高分子量核仁素形式的自催化裂解，而核仁素mRNA浓度没有改变。因此，核仁素通过缺氧诱导因子非依赖性途径改变翻译效率是缺氧条件下C-P4 H-α（I）调节的重要步骤。
Hypoxia is a pro-fibrotic stimulus, which is associated with enhanced collagen synthesis, as well as with augmented collagen prolyl 4-hydroxylase (C-P4H) activity. C-P4H activity is controlled mainly by regulated expression of the alpha C-P4H subunit. In this study we demonstrate that the increased synthesis of C-P4H-alpha(I) protein in human HT1080 fibroblasts under long term hypoxia (36 h, 1% oxygen) is controlled at the translational level. This is mediated by an interaction of RNA-binding protein nucleolin (similar to 64 kDa form) at the 5'-and 3'-untranslated regions (UTR) of themRNA. The 5'/3'-UTR-dependent mechanism elevates the C-P4H-alpha(I) expression rate 2.3-fold, and participates in a 5.3-fold increased protein level under long term hypoxia. The interaction of nucleolin at the 5'-UTR occurs directly and depends on the existence of an AU-rich element. Statistical evaluation of the similar to 64-kDa nucleolin/ RNA interaction studies revealed a core binding sequence, corresponding to UAAAUC or AAAUCU. At the 3'-UTR, nucleolin assembles indirectly via protein/ protein interaction, with the help of another 3'-UTR-binding protein, presumably annexin A2. The increased protein level of the similar to 64-kDa nucleolin under hypoxia can be attributed to an autocatalytic cleavage of a high molecular weight nucleolin form, without alterations in nucleolin mRNA concentration. Thus, the alteration of translational efficiency by nucleolin, which occurs through a hypoxia inducible factor independent pathway, is an important step in C-P4H-alpha(I) regulation under hypoxia.