Hypoxia regulates β-enolase and pyruvate kinase-M promoters by modulating Sp1/Sp3 binding to a conserved GC element
Hypoxia regulates β-enolase and pyruvate kinase-M promoters by modulating Sp1/Sp3 binding to a conserved GC element
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DOI：
10.1074/jbc.273.40.26087
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发表时间：
1998-10-02
影响因子：
4.8
通讯作者：
Webster, KA
中科院分区：
文献类型：
--
作者：
Discher, DJ;Bishopric, NH;Webster, KA
当细胞暴露于低氧张力时，糖酵解酶基因的转录率被协调诱导。这种效应已在许多细胞类型中得到描述，并且不限于物种或门。哺乳动物细胞中有 11 种不同的糖酵解酶，其中至少有 9 种是由缺氧诱导的。最近的报告描述了缺氧诱导因子-1 (HIF-1) 在乳酸脱氢酶 A、醛缩酶-A、磷酸甘油酸激酶和烯醇化酶-1 基因转录激活中的作用。目前尚不清楚 HIF-1 因子是否专门在缺氧期间调节这些基因，或者该途径的其他基因如何受到调节。在本文中，我们描述了对肌肉特异性丙酮酸激酶-M和β-烯醇化酶启动子的分析，这些启动子暗示了缺氧调节糖酵解酶基因转录的其他机制。当转染的肌肉细胞暴露于缺氧时，由任一启动子指导的报告基因的瞬时转录被激活。这些启动子都不含有 HIF-1 结合位点。相反，缺氧反应定位于紧邻两个基因近端启动子区域的 GATAA 位点上游的富含 GC 的保守元件。 GC元件对于基础和缺氧诱导的表达都是必需的，并且结合转录因子Spl和Sp3。 DNA 结合研究和 Western 分析确定，缺氧导致 Sp3 进行性耗竭，而 Spl 蛋白水平保持不变，Sp3 的过度表达抑制 p-烯醇酶启动子的表达。结论是缺氧通过下调 Sp3 来激活这些糖酵解酶基因启动子，从而消除相关的转录抑制。
The transcription rates of glycolytic enzyme genes are coordinately induced when cells are exposed to low oxygen tension. This effect has been described in many cell types and is not restricted to species or phyla. In mammalian cells, there are 11 distinct glycolytic enzymes, at least 9 of which are induced by hypoxia. Recent reports described a role for the hypoxia-inducible factor-1 (HIF-1) in the transcriptional activation of lactate dehydrogenase A, aldolase-A, phosphoglycerate kinase, and enolase-l genes. It is not known whether the HIF-1 factor acts exclusively to regulate these genes during hypoxia, or how the other genes of the pathway are regulated. In this paper, we describe analyses of the muscle-specific pyruvate kinase-M and beta-enolase promoters that implicate additional mechanisms for the regulation of glycolytic enzyme gene transcription by hypoxia, Transient transcription of a reporter gene directed by either promoter was activated when transfected muscle cells were exposed to hypoxia. Neither of these promoters contain HIF-1 binding sites. Instead, the hypoxia response was localized to a conserved GC-rich element positioned immediately upstream of a GATAA site in the proximal promoter regions of both genes. The GC element was essential for both basal and hypoxia-induced expression and bound the transcription factors Spl and Sp3. Hypoxia caused the progressive depletion of Sp3 determined by DNA binding studies and Western analyses, whereas Spl protein levels remained unchanged, Overexpression of Sp3 repressed expression of p-enolase promoters. It is concluded that hypoxia activates these glycolytic enzyme gene promoters by down-regulating Sp3, thereby removing the associated transcriptional repression.