Appelhoff Rebecca J, Tian Ya-Min, Raval Raju R, Turley Helen, Harris Adrian L, Pugh Christopher W, Ratcliffe Peter J, Gleadle Jonathan M
Henry Wellcome Bldg. of Genomic Medicine, Roosevelt Drive, Headington, Oxford, UK.
J Biol Chem. 2004 Sep 10;279(37):38458-65. doi: 10.1074/jbc.M406026200. Epub 2004 Jul 7.
Hypoxia-inducible factor (HIF) is a transcriptional regulator that plays a key role in many aspects of oxygen homeostasis. The heterodimeric HIF complex is regulated by proteolysis of its alpha-subunits, following oxygen-dependent hydroxylation of specific prolyl residues. Although three HIF prolyl hydroxylases, PHD1, PHD2, and PHD3, have been identified that have the potential to catalyze this reaction, the contribution of each isoform to the physiological regulation of HIF remains uncertain. Here we show using suppression by small interference RNA that each of the three PHD isoforms contributes in a non-redundant manner to the regulation of both HIF-1alpha and HIF-2alpha subunits and that the contribution of each PHD under particular culture conditions is strongly dependent on the abundance of the enzyme. Thus in different cell types, isoform-specific patterns of PHD induction by hypoxia and estrogen alter both the relative abundance of the PHDs and their relative contribution to the regulation of HIF. In addition, the PHDs manifest specificity for different prolyl hydroxylation sites within each HIF-alpha subunit, and a degree of selectively between HIF-1alpha and HIF-2alpha isoforms, indicating that differential PHD inhibition has the potential to selectively alter the characteristics of HIF activation.
缺氧诱导因子（HIF）是一种转录调节因子，在氧稳态的许多方面发挥关键作用。异二聚体HIF复合物通过其α亚基的蛋白水解进行调节，这发生在特定脯氨酰残基的氧依赖性羟基化之后。虽然已经鉴定出三种HIF脯氨酰羟化酶，即PHD1、PHD2和PHD3，它们有可能催化这一反应，但每种同工型对HIF生理调节的贡献仍不确定。在这里，我们使用小干扰RNA抑制实验表明，三种PHD同工型中的每一种都以非冗余方式对HIF-1α和HIF-2α亚基的调节起作用，并且在特定培养条件下每种PHD的贡献强烈依赖于该酶的丰度。因此，在不同细胞类型中，缺氧和雌激素诱导的PHD同工型特异性模式既改变了PHD的相对丰度，也改变了它们对HIF调节的相对贡献。此外，PHD对每个HIF-α亚基内不同的脯氨酰羟基化位点表现出特异性，并且在HIF-1α和HIF-2α同工型之间具有一定程度的选择性，这表明差异性PHD抑制有可能选择性地改变HIF激活的特征。
