Disruption of Hypoxia-Inducible Transcription Factor-Prolyl Hydroxylase Domain-1 (PHD-1^−/−) Attenuates Ex Vivo Myocardial Ischemia/Reperfusion Injury Through Hypoxia-Inducible Factor-1α Transcription Factor and Its Target Genes in Mice

Abstract

Hypoxia-inducible transcription factor (HIF)-prolyl hydroxylases domain (PHD-1-3) are oxygen sensors that regulate the stability of the HIFs in an oxygen-dependent manner. Suppression of PHD enzymes leads to stabilization of HIFs and offers a potential treatment option for many ischemic disorders, such as peripheral artery occlusive disease, myocardial infarction, and stroke. Here, we show that homozygous disruption of PHD-1 (PHD-1(-/-)) could facilitate HIF-1α-mediated cardioprotection in ischemia/reperfused (I/R) myocardium. Wild-type (WT) and PHD-1(-/-) mice were randomized into WT time-matched control (TMC), PHD-1(-/-) TMC (PHD1TMC), WT I/R, and PHD-1(-/-) I/R (PHD1IR). Isolated hearts from each group were subjected to 30 min of global ischemia followed by 2 h of reperfusion. TMC hearts were perfused for 2 h 30 min without ischemia. Decreased infarct size (35%±0.6% vs. 49%±0.4%) and apoptotic cardiomyocytes (106±13 vs. 233±21 counts/100 high-power field) were observed in PHD1IR compared to wild-type ischemia/reperfusion (WTIR). Protein expression of HIF-1α was significantly increased in PHD1IR compared to WTIR. mRNA expression of β-catenin (1.9-fold), endothelial nitric oxide synthase (1.9-fold), p65 (1.9-fold), and Bcl-2 (2.7-fold) were upregulated in the PHD1IR compared with WTIR, which was studied by real-time quantitative polymerase chain reaction. Further, gel-shift analysis showed increased DNA binding activity of HIF-1α and nuclear factor-kappaB in PHD1IR compared to WTIR. In addition, nuclear translocation of β-catenin was increased in PHD1IR compared with WTIR. These findings indicated that silencing of PHD-1 attenuates myocardial I/R injury probably by enhancing HIF-1α/β-catenin/endothelial nitric oxide synthase/nuclear factor-kappaB and Bcl-2 signaling pathway.

Regulation of IL-1β–induced NF-κB by hydroxylases links key hypoxic and inflammatory signaling pathways

“…Based on these observations, it would be predicted that pharmacologic hydroxylase inhibition in vivo would promote inflammation. However, a number of recent studies have somewhat paradoxically demonstrated a profoundly anti-inflammatory effect of hydroxylase inhibition in multiple models of acute and chronic inflammation (10,11,15,32). In the current study, we investigated the underlying mechanism(s) of anti-inflammatory action of hydroxylase inhibition with an aim to develop our understanding of the role of hydroxylases in regulating inflammatory signaling pathways and the potential for hydroxylase inhibitors as anti-inflammatory therapeutics.…”

“…The same hydroxylases that confer hypoxic sensitivity upon HIF have been reported to be responsible for the hypoxic sensitivity of NF-κB (9). Whereas PHDs have been implicated in the regulation of NF-κB, the functional site(s) of proline hydroxylation in the pathway has yet to be identified (9)(10)(11). Conversely, FIH-dependent asparagine hydroxylation sites on a number of key proteins in the NF-κB pathway have been identified; however, the functional impact of this remains unclear (12,13).…”

Hypoxia-Inducible Factor-1a Dependent Pathways Mediate the Renoprotective Role of Acetazolamide Against Renal Ischemia-Reperfusion Injury

“…HIF-1α plays an important protective role against AKI [14,26,27], which is related to its downstream proteins including the vascular endothelial growth factor (VEGF) [28], NOS [12,29] and Bcl-2 [30,31]. Based on our previous findings, we hypothesised that AZA performed its renoprotective function by modulating eNOS and Bcl-2 which could be connected with HIF-1α.…”

“…It has been well documented that HIF-1α plays a crucial role in ameliorating I/R injury in different organs, such as brain [11], heart [12], liver [13] and kidney [14]. Therefore, pharmacological methods to regulate HIF-1α are intensively pursued.…”

Risk Factors in Heart Disease: Therapeutic Interventions

“…The original article by Adluri et al (1) documented that disruption of hypoxia-inducible factor-prolyl hydroxylase-1 leads to cardioprotection by stabilization of hypoxiainducible factor-1a followed by increased mRNA expression of proangiogenic and antiapoptotic molecules in the ischemic/reperfused myocardium. Again, the cardioprotective effects of Heme oxygenase-1 (HO-1), a stress response protein that provides antioxidant and anti-inflammatory activity, are extensively surveyed by Wu et al (23).…”