Lando David, Peet Daniel J, Whelan Dean A, Gorman Jeffrey J, Whitelaw Murray L
Department of Molecular Biosciences (Biochemistry), Adelaide University, SA 5005, Australia.
Science. 2002 Feb 1;295(5556):858-61. doi: 10.1126/science.1068592.
The hypoxia-inducible factors (HIFs) 1alpha and 2alpha are key mammalian transcription factors that exhibit dramatic increases in both protein stability and intrinsic transcriptional potency during low-oxygen stress. This increased stability is due to the absence of proline hydroxylation, which in normoxia promotes binding of HIF to the von Hippel-Lindau (VHL tumor suppressor) ubiquitin ligase. We now show that hypoxic induction of the COOH-terminal transactivation domain (CAD) of HIF occurs through abrogation of hydroxylation of a conserved asparagine in the CAD. Inhibitors of Fe(II)- and 2-oxoglutarate-dependent dioxygenases prevented hydroxylation of the Asn, thus allowing the CAD to interact with the p300 transcription coactivator. Replacement of the conserved Asn by Ala resulted in constitutive p300 interaction and strong transcriptional activity. Full induction of HIF-1alpha and -2alpha, therefore, relies on the abrogation of both Pro and Asn hydroxylation, which during normoxia occur at the degradation and COOH-terminal transactivation domains, respectively.
缺氧诱导因子（HIFs）1α和2α是关键的哺乳动物转录因子，在低氧应激期间，其蛋白质稳定性和内在转录活性均显著增加。这种稳定性的增加是由于脯氨酸羟基化的缺失，在常氧条件下，脯氨酸羟基化会促进HIF与冯·希佩尔-林道（VHL肿瘤抑制因子）泛素连接酶的结合。我们现在表明，HIF的羧基末端反式激活结构域（CAD）的缺氧诱导是通过CAD中一个保守天冬酰胺的羟基化缺失来实现的。依赖于铁（II）和2-氧戊二酸的双加氧酶抑制剂可阻止天冬酰胺的羟基化，从而使CAD能够与p300转录共激活因子相互作用。用丙氨酸取代保守的天冬酰胺会导致组成型p300相互作用和强大的转录活性。因此，HIF-1α和-2α的完全诱导依赖于脯氨酸和天冬酰胺羟基化的缺失，在常氧条件下，它们分别发生在降解结构域和羧基末端反式激活结构域。
