Inhibition of HIF-prolyl-4-hydroxylases prevents mitochondrial impairment and cell death in a model of neuronal oxytosis

Abstract

Mitochondrial impairment induced by oxidative stress is a main characteristic of intrinsic cell death pathways in neurons underlying the pathology of neurodegenerative diseases. Therefore, protection of mitochondrial integrity and function is emerging as a promising strategy to prevent neuronal damage. Here, we show that pharmacological inhibition of hypoxia-inducible factor prolyl-4-hydroxylases (HIF-PHDs) by adaptaquin inhibits lipid peroxidation and fully maintains mitochondrial function as indicated by restored mitochondrial membrane potential and ATP production, reduced formation of mitochondrial reactive oxygen species (ROS) and preserved mitochondrial respiration, thereby protecting neuronal HT-22 cells in a model of glutamate-induced oxytosis. Selective reduction of PHD1 protein using CRISPR/Cas9 technology also reduced both lipid peroxidation and mitochondrial impairment, and attenuated glutamate toxicity in the HT-22 cells. Regulation of activating transcription factor 4 (ATF4) expression levels and related target genes may mediate these beneficial effects. Overall, these results expose HIF-PHDs as promising targets to protect mitochondria and, thereby, neurons from oxidative cell death.

Hypoxia‐inducible factors as neuroprotective agent in Alzheimer's disease

“…Karuppagounder and Ratan proposed that inhibition of PHD as a novel target to enhance the HIF level in stroke therapy . Neitemeier et al . concluded that HIF‐PHDs can be a promising target to protect the mitochondria‐mediated neuron death.…”

“…They have also been found in several disease processes including the progression of cancer via inflammation, antiapoptosis, angiogenesis and malignant cell proliferation . Though recent experimental studies have demonstrated the stabilization of their level has a neuroprotective effect on the brain, knowledge of their exact role in AD is scant . Therefore, information on the HIFs, mainly their regulation and possible role as neuroprotector in AD will be worthwhile to the scientific community.…”

Sex differences in neonatal mouse brain injury after hypoxia‐ischemia and adaptaquin treatment

“…Pharmacological inhibition of HIF‐PHD using iron chelators such as deferoxamine (Yao et al, ) or genetic approaches through knockout of PHD1 and PHD2 (Li et al, ; Quaegebeur et al, ) prevented neuronal cell death. These findings indicated that HIF‐PHD inhibition might involve a newly identified form of programmed cell death called ferroptosis, which is a non‐apoptotic form of cell death that depends on cellular iron, lipid‐based ROS formation, and the loss of GPX4 activity (Neitemeier et al, ; Stockwell et al, ; Wu et al, ). Further, it has been shown that AQ can inhibit mitochondrial demise by reducing ROS production, thereby maintaining mitochondrial function (Neitemeier et al, ), preventing neuronal death (Niatsetskaya et al, ), and improving functional outcome after brain injury (Karuppagounder et al, ).…”

“…These findings indicated that HIF‐PHD inhibition might involve a newly identified form of programmed cell death called ferroptosis, which is a non‐apoptotic form of cell death that depends on cellular iron, lipid‐based ROS formation, and the loss of GPX4 activity (Neitemeier et al, ; Stockwell et al, ; Wu et al, ). Further, it has been shown that AQ can inhibit mitochondrial demise by reducing ROS production, thereby maintaining mitochondrial function (Neitemeier et al, ), preventing neuronal death (Niatsetskaya et al, ), and improving functional outcome after brain injury (Karuppagounder et al, ). In this study, even though AQ treatment achieved pronounced neuroprotection both in grey matter and white matter in the neonatal HI brain injury model, it only caused a mild reduction in the number of Fluoro‐Jade–labeled cells in the cortex and had no effect on caspase‐dependent and caspase‐independent neuronal cell death.…”

“…Hypoxia‐inducible factor prolyl‐4‐hydroxylase domain (HIF‐PHD) is an important target against mitochondrial damage, and inhibition of HIF‐PHD prevents neuronal cell death induced by mitochondrial damage resulting from oxidative stress in vitro and ischemic injury in vivo (Karuppagounder et al, ; Neitemeier et al, ; Quaegebeur et al, ). HIF‐PHD is a non‐heme, Fe 2+ ‐dependent enzyme belonging to the 2‐oxoglutarate‐dependent oxygenase superfamily, which is the main regulator of hypoxia response.…”