Nitric Oxide Donor, (±)-S-Nitroso-N-acetylpenicillamine, Stabilizes Transactive Hypoxia-Inducible Factor-1α by Inhibiting von Hippel-Lindau Recruitment and Asparagine Hydroxylation

Abstract

We have confirmed that the NO donor (Ϯ)-S-nitroso-Nacetylpenicillamine (SNAP) stabilizes the transactive form of hypoxia-inducible factor-1␣ (HIF-1␣), leading to the induction of HIF-1␣ target genes such as vascular endothelial growth factor and carbonic anhydrase 9. Activation of HIF-1␣ should require inhibition of the dual system that keeps it inactive. One is ubiquitination, which is triggered by hydroxylation of HIF-1␣-proline and the subsequent binding of E3 ubiquitin ligase, the von Hippel Lindau (VHL) protein. The other is hydroxylation of HIF-1␣-asparagine, which reduces the affinity of HIF-1␣ for its coactivator, cAMP responsive element binding protein/p300. We examined the effects of the NO donor SNAP on proline and asparagine hydroxylation of HIF-1␣ peptides by measuring the activities of the corresponding enzymes, HIF-1␣-specific proline hydroxylase 2 (PHD2) and the HIF-1␣-specific asparagine hydroxylase, designated factor inhibiting HIF-1␣ (FIH-1), respectively. We found that the SNAP did not prevent PHD2 from hydroxylating the proline of HIF-1␣. Instead, it blocked the interaction between VHL and the proline-hydroxylated HIF-1␣, but only when the reducing agents Fe(II) and vitamin C were limiting. The fact that the absence of cysteine 520 of HIF-1␣ abolishes its responsiveness to SNAP suggests that this residue mediates the inhibition by SNAP of the interaction between VHL and HIF-1␣, presumably by S-nitrosylation of HIF-1␣. Unlike PHD2, asparagine hydroxylation by FIH-1 was directly inhibited by SNAP, but again only when reducing agents were limiting. Substitution of cysteine 800 of HIF-1␣ with alanine failed to reverse the inhibitory effects of SNAP on asparagine hydroxylation, implying that FIH-1, not its substrate HIF-1␣, is inhibited by SNAP.Hypoxia-inducible factor-1 (HIF-1), a heterodimeric transcription factor, is a master transcription activator responsible for gene induction under hypoxic conditions (Semenza, 2000). It is composed of an ␣ subunit and a ␤ subunit. HIF-1␣ is ubiquitinated and rapidly degraded under normoxic conditions (Jaakkola et al., 2001). The stability and activity of the ␣ subunit of HIF-1 are regulated by post-translational modification, specifically by hydroxylation. Proline residues 402 and 564 of the oxygen-dependent degradation domain (ODD; amino acids 401-603 of human HIF-1␣) are hydroxylated, mainly by HIF-1␣-specific proly-4-hydroxylase 2 (PHD2)

Endothelial Cell-Derived Nitric Oxide Enhances Aerobic Glycolysis in Astrocytes via HIF-1 -Mediated Target Gene Activation

“…MCT4 mRNA levels are shown as mean Ϯ SEM of triplicate samples, repeated three times on different cell preparations with similar results. normoxic conditions (Sandau et al, 2001;Kasuno et al, 2004;Park et al, 2008) and destabilization under hypoxic conditions (Sogawa et al, 1998). Here, we detected HIF-1␣ stabilization under normoxic conditions in NO-treated astrocytes, but not in neurons.…”

Hydroxylase-dependent regulation of the NF-κB pathway

“…Studies using recombinant proteins suggested that the effect of NO upon PHD2 was irreversible; however in studies in cell culture, NO-induced reduction of HIF-1 α -hydroxylation was found to be reversible (Metzen et al , 2003 ;Berchner -Pfannschmidt et al, 2007 ;Tug et al , 2009 ). It has also been suggested that FIH is inhibited by NO; nonetheless, this was demonstrated only when iron and ascorbate were limiting (Metzen et al , 2003 ;Park et al , 2008 ). On the other hand, HIF-dependent target genes, such as PHD2, are up-regulated in response to NO, indicating the inhibition of both PHDs and FIH (Kimura et al , 2000 ;Berchner -Pfannschmidt et al, 2007 ).…”

Regulation of pancreatic β-cell survival by nitric oxide

“…118 On the other hand, NO increases the stability and transcriptional activity of HIF-1α by disrupting its interaction with VHL, perhaps through the S-nitrosylation of Cys800 of HIF-1α. 124 Furthermore, several conditions, such as shear stress or Brainderived neurotrophic factor (BDNF), induce nuclear localization of NO, where NO may induce class II HDAC and SIRT1 S-nitrosylation and promote chromatin-remodelling, thereby broadly regulates gene expression. 125,126 All of these actions may be due to the post-translation modification of these transcriptional regulation components.…”