REGULATION OF GLUT1 GENE EXPRESSION BY HYPOXIA

描述(改编自申请人的摘要)：规定 葡萄糖通过质膜的转运对 细胞代谢正常，血糖稳态，糖尿病高血糖。 无处不在的GLUT1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，胞浆钙升高， 低氧和氧化磷酸化的抑制。调查人员 已经表明，细胞内GLUT1 mRNA含量的增加是对 叠氮对氧化磷酸化的抑制作用是由两种途径介导的 增强GLUT1的转录，降低GLUT1的降解。最近 研究人员进行了一项新的观察，发现GLUT1在一个 氯化钴[Co(II)]显著增加了细胞系的数量， 刺激低氧反应基因表达的试剂； 这个基因家族的成员可以被低氧上调，但不能被抑制剂上调。 氧化磷酸化。因此，GLUT1似乎是第一个示例 其表达受低氧双重调节的基因，即 通过降低氧气浓度本身，以及通过随行人员 氧化磷酸化的抑制。调查人员还发现 GLUT1启动子/5‘-侧翼区的不同区域是 对叠氮和钴(II)的转录反应是必需的。在……里面 此外，一个480个碱基对的DNA片段位于约3.5kBP的上游 Glut1转录起始点是一种“增强子”，对于 对Co(II)的反应，并含有一个缺氧诱导元件(HIE)。 最近，调查人员发现了一个666个BP的区域 出现的转录起始点上游约6kBP 负责刺激GLUT1基因转录的反应 去阿齐德。基于上述发现，本文提出了研究建议。 申请续批以检验以下假设：1) GLUT1启动子区域的不同元件介导转录 对叠氮和钴(11)的反应；2)GLUT1基因和 特异性RNA结合因子介导GLUT1的稳定性 叠氮、钙离子载体和茴香素处理的细胞中的mrna。 这些研究的结果将有助于我们更好地理解 GLUT1葡萄糖转运体在多种生理和病理组织中的表达 病理生理条件，尤指适应反应的条件 低氧和氧化磷酸化的抑制。

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.