Oxygen-regulated expression of the RNA-binding proteins RBM3 and CIRP by a HIF-1-independent mechanism
Oxygen-regulated expression of the RNA-binding proteins RBM3 and CIRP by a HIF-1-independent mechanism
复制标题
DOI：
10.1242/jcs.01026
复制
发表时间：
2004-04-01
影响因子：
4
通讯作者：
Seeger, K
中科院分区：
文献类型：
--
作者：
Wellmann, S;Bührer, C;Seeger, K
低氧诱导因子1（hypoxiinducible factor 1，HIF-1）是一种由HIF-1 α和HIF-1 β两个亚基组成的异源二聚体蛋白质，它介导了几十个基因对低氧张力的转录调控。在HIF-1 α缺陷的人白血病细胞系Z-33中，暴露于轻度（8%O-2）或重度（1%O-2）缺氧，我们发现两种相关的异质性核核糖核蛋白，RNA结合基序蛋白3（RBM 3）和冷诱导RNA结合蛋白（CIRP），这是高度保守的冷应激蛋白与RNA结合特性的显着上调。缺氧也诱导RBM 3和CIRP在鼠HIF-1 β缺陷细胞系Hepa-1 c4中的上调。在不同的HIF-1感受态细胞中，RBM 3和CIRP被中度低温（32 ℃）诱导，但低温在增加HIF-1 α或血管内皮生长因子（VEGF）（一种已知的HIF-1靶点）方面无效。相反，铁螯合剂诱导VEGF，但不诱导RBM 3或CIRP。缺氧后RBM 3和CIRP mRNA的增加被放线菌素D抑制，体外核运行试验表明缺氧后RBM 3和CIRP mRNA的特异性增加，这表明调节发生在基因转录水平。呼吸链抑制剂NaN 3和氰化物以剂量依赖性方式抑制缺氧诱导的RBM 3或CIRP转录。然而，耗尽线粒体的细胞仍然能够响应于缺氧而上调RBM 3和CIRP。因此，RBM 3和CIRP通过既不涉及HIF-1也不涉及线粒体的机制响应于缺氧而适应性表达。
The transcriptional regulation of several dozen genes in response to low oxygen tension is mediated by hypoxiainducible factor 1 (HIF-1), a heterodimeric protein composed of two subunits, HIF-1alpha and HIF-1beta. In the HIF-1alpha-deficient human leukemic cell line, Z-33, exposed to mild (8% O-2) or severe (1% O-2) hypoxia, we found significant upregulation of two related heterogenous nuclear ribonucleoproteins, RNA-binding motif protein 3 (RBM3) and cold inducible RNA-binding protein (CIRP), which are highly conserved cold stress proteins with RNA-binding properties. Hypoxia also induced upregulation of RBM3 and CIRP in the murine HIF-1beta-deficient cell line, Hepa-1 c4. In various HIF-1 competent cells, RBM3 and CIRP were induced by moderate hypothermia (32degreesC) but hypothermia was ineffective in increasing HIF-1alpha or vascular endothelial growth factor (VEGF), a known HIF-1 target. In contrast, iron chelators induced VEGF but not RBM3 or CIRP. The RBM3 and CIRP mRNA increase after hypoxia was inhibited by actinomycin-D, and in vitro nuclear run-on assays demonstrated specific increases in RBM3 and CIRP mRNA after hypoxia, which suggests that regulation takes place at the level of gene transcription. Hypoxia-induced RBM3 or CIRP transcription was inhibited by the respiratory chain inhibitors NaN3 and cyanide in a dose-dependent fashion. However, cells depleted of mitochondria were still able to upregulate RBM3 and CIRP in response to hypoxia. Thus, RBM3 and CIRP are adaptatively expressed in response to hypoxia by a mechanism that involves neither HIF-1 nor mitochondria.