REGULATION OF GLUT1 GENE EXPRESSION BY HYPOXIA

描述（改编自申请人的摘要）： 葡萄糖跨质膜转运对于 正常细胞代谢、葡萄糖稳态和糖尿病的高血糖症。 普遍存在的GLUT 1葡萄糖转运蛋白的表达被增强， 几种刺激包括血清、甲状腺激素、胞质钙升高， 缺氧和氧化磷酸化抑制。 调查人员 已经表明，细胞GLUT 1 mRNA含量的增加， 叠氮化物对氧化磷酸化的抑制作用是由 GLUT 1 mRNA的转录增强和降解减少。 最近 研究人员发现，GLUT 1在一个细胞中的表达， 氯化钴[Co（II）]显著增加了细胞系的数量， 刺激低氧应答基因表达的试剂; 该基因家族的成员被缺氧上调，但不被抑制剂上调 氧化磷酸化反应 因此，GLUT 1似乎是第一个例子 一个基因的表达受到缺氧的双重调控，即 通过氧气浓度本身的降低， 氧化磷酸化的抑制。 调查人员还发现， GLUT 1启动子/5 '-侧翼区的不同区域 叠氮化物和钴（II）的转录反应所必需的。 在 此外，一个480 bp的DNA片段位于约3.5 kbp的上游， GLUT 1转录起始位点作为“增强子”发挥功能，对于 对Co（II）的反应，并含有缺氧诱导元件（HIE）。 最近，研究人员发现了一个666 bp的区域， 转录起始位点上游约6 kbp， 负责刺激GLUT 1基因转录， 叠氮化物。 基于上述研究结果，本文提出了一些研究建议。 继续补助金申请，以测试以下假设：1） GLUT 1启动子区域中的不同元件介导了GLUT 1基因的转录。 对叠氮化物和Co（II）的响应; 2）GLUT 1 mRNA中含有的序列， 特异性RNA结合因子介导观察到的GLUT 1稳定 用叠氮化物、钙离子载体和茴香霉素处理的细胞中的mRNA。 这些研究的结果将加深我们对 GLUT 1葡萄糖转运蛋白在许多生理和 病理生理条件，特别是适应性反应的条件 缺氧和氧化磷酸化抑制。

DESCRIPTION (Adapted from applicant's abstract): Regulation of the rate of glucose transport across plasma membranes is of fundamental importance to normal cell metabolism, glucose homeostasis, and hyperglycemia of diabetes. Expression of the ubiquitous GLUT1 glucose transporter is augmented by several stimuli including serum, thyroid hormone, rise in cytosolic calcium, hypoxia, and inhibition of oxidative phosphorylation. The investigators have shown that the increase in cell GLUT1 mRNA content in response to inhibition of oxidative phosphorylation by azide is mediated by both enhanced transcription and decreased degradation of GLUT1 mRNA. Recently the investigators have made the novel observation that GLUT1 expression in a number of cell lines is markedly augmented by cobalt(II) chloride [Co(II)], an agent which stimulates the expression of hypoxia-responsive genes; members of this gene family are upregulated by hypoxia but not by inhibitors of oxidative phosphorylation. Hence, GLUT1 appears to be the first example of a gene whose expression is regulated in a dual fashion by hypoxia, namely by a reduction in oxygen concentration per se, and by the attendant inhibition of oxidative phosphorylation. The investigators have also found that different regions of the GLUT1 promoter/5'-flanking region are necessary for the transcriptional response to azide and Co(II). In addition, a 480-bp DNA segment located approximately 3.5 kbp upstream of the GLUT1 transcription start-site functions as an "enhancer", is essential for the response to Co(II), and contains an hypoxia-inducible-element (HIE). More recently the investigators have identified a 666-bp region located approximately 6 kbp upstream of the transcription start-site which appears to be responsible for the stimulation o GLUT1 gene transcription in response to azide. Based on the above findings, studies are proposed in this continuation grant application to test the following hypotheses: 1) Different elements in the GLUT1 promoter region mediate the transcriptional response to azide and Co(ll); 2) Sequences contained in GLUT1 mRNA and specific RNA binding factors mediate the observed stabilization of GLUT1 mRNA in cells treated with azide, calcium ionophores, and anisomycin. Results of these studies will enhance our understanding of the regulation of the GLUTl glucose transporter expression in a number of physiological and pathophysiological conditions, especially those of the adaptive response to hypoxia and to inhibition of oxidative phosphorylation.