Inhibition of Prolyl Hydroxylase Protects against 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced Neurotoxicity: MODEL FOR THE POTENTIAL INVOLVEMENT OF THE HYPOXIA-INDUCIBLE FACTOR PATHWAY IN PARKINSON DISEASE

Donna W Lee,Subramanian Rajagopalan,Ambreena Siddiq,Roberto Gwiazda,Lichuan Yang,M.Flint Beal,Rajiv R Ratan,Julie K Andersen

doi:10.1074/jbc.m109.000638

Abstract

Hypoxia-inducible factor (HIF) plays an important role in cell survival by regulating iron, antioxidant defense, and mitochondrial function. Pharmacological inhibitors of the iron-dependent enzyme class prolyl hydroxylases (PHD), which target alpha subunits of HIF proteins for degradation, have recently been demonstrated to alleviate neurodegeneration associated with stroke and hypoxic-ischemic injuries. Here we report that inhibition of PHD by 3,4-dihydroxybenzoate (DHB) protects against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced nigral dopaminergic cell loss and up-regulates HIF-1alpha within these neurons. Elevations in mRNA and protein levels of HIF-dependent genes heme oxygenase-1 (Ho-1) and manganese superoxide dismutase (Mnsod) following DHB pretreatment alone are also maintained in the presence of MPTP. MPTP-induced reductions in ferroportin and elevations in nigral and striatal iron levels were reverted to levels comparable with that of untreated controls with DHB pretreatment. Reductions in pyruvate dehydrogenase mRNA and activity resulting from MPTP were also found to be attenuated by DHB. In vitro, the HIF pathway was activated in N27 cells grown at 3% oxygen treated with either PHD inhibitors or an iron chelator. Concordant with our in vivo data, the MPP(+)-elicited increase in total iron as well as decreases in cell viability were attenuated in the presence of DHB. Taken together, these data suggest that protection against MPTP neurotoxicity may be mediated by alterations in iron homeostasis and defense against oxidative stress and mitochondrial dysfunction brought about by cellular HIF-1alpha induction. This study provides novel data extending the possible therapeutic utility of HIF induction to a Parkinson disease model of neurodegeneration, which may prove beneficial not only in this disorder itself but also in other diseases associated with metal-induced oxidative stress.

Highlights

An important family of enzymes that require iron as an essential cofactor are the prolyl 4-hydroxylases (PHDs), which serve to hydroxylate proline residues situated within hypoxiainducible factor proteins (HIFs) [7]
PHD Inhibition Protects against MPTP-induced DAergic Cell Loss and Striatal Denervation—Based on the hypothesis that an inhibition of iron-dependent PHD activity could result in the accumulation of HIF-1␣ and a HIF-mediated activation of prosurvival gene products, it was postulated that DHB may reduce the extent of DAergic injury induced by systemic MPTP treatment in young adult mice
DHB is a low molecular weight inhibitor of PHD that displaces 2-oxoglutarate or ascorbate, co-factors required for PHD activity [17], and has been shown to reduce infarct volume induced by middle cerebral artery occlusion [10]

Summary

Introduction

An important family of enzymes that require iron as an essential cofactor are the prolyl 4-hydroxylases (PHDs), which serve to hydroxylate proline residues situated within hypoxiainducible factor proteins (HIFs) [7]. Pyridine; DMOG, dimethyloxaloylglycine; DHB, dihydroxybenzoate; SIH, salicylaldehyde isonicotinoyl hydrazone; PHD, prolyl 4-hydroxylase; HO-1, heme oxygenase-1; SN, substantia nigra; ST, striatum; VEGF, vascular endothelial growth factor; MnSOD, manganese superoxide dismutase; TH, tyrosine hydroxylase; MPTP, 1-methyl-4-phenyl-1,2,3,6tetrahydropyridine; CQ, clioquinol; HPLC, high pressure liquid chromatography; RT, reverse transcriptase; BisTris, 2-[bis(2-hydroxyethyl)amino]-2-(hydroxymethyl)propane-1,3-diol; TES, 2-{[2-hydroxy-1,1bis(hydroxymethyl)ethyl]amino}ethanesulfonic acid; FPT, ferroportin; ICP-MS, inductively coupled plasma-mass spectrometry; PDH, pyruvate dehydrogenase; SNpc, substantia nigra pars compacta. Previous studies have demonstrated that deferoxamine, an iron chelator, can activate HIF-1␣ and prevent neuronal death in both in vitro and in vivo models of ischemia likely via inhibition of PHDs [8, 9]. We demonstrate here that PHD inhibition increases induction of HIF and HIF-related genes, functionally impacts on parameters of iron homeostasis and metabolic function, and, most importantly, significantly reduces the extent of DAergic nigrostriatal injury observed in the well established murine MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) PD model

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Conclusion