Inhibition of Peroxynitrite-Induced Mitophagy Activation Attenuates Cerebral Ischemia-Reperfusion Injury

Abstract

Activated autophagy/mitophagy has been intensively observed in ischemic brain, but its roles remain controversial. Peroxynitrite (ONOO), as a representative of reactive nitrogen species, is considered as a critical neurotoxic factor in mediating cerebral ischemia-reperfusion (I/R) injury, but its roles in autophagy/mitophagy activation remain unclear. Herein, we hypothesized that ONOO could induce PINK1/Parkin-mediated mitophagy activation via triggering dynamin-related protein 1 (Drp1) recruitment to damaged mitochondria, contributing to cerebral I/R injury. Firstly, we found PINK1/Parkin-mediated mitophagy activation was predominant among general autophagy, leading to rat brain injury at the reperfusion phase after cerebral ischemia. Subsequently, increased nitrotyrosine was found in the plasma of ischemic stroke patients and ischemia-reperfused rat brains, indicating the generation of ONOO in ischemic stroke. Moreover, in vivo animal experiments illustrated that ONOO was dramatically increased, accompanied with mitochondrial recruitment of Drp1, PINK1/Parkin-mediated mitophagy activation, and progressive infarct size in rat ischemic brains at the reperfusion phase. FeTMPyP, a peroxynitrite decomposition catalyst, remarkably reversed mitochondrial recruitment of Drp1, mitophagy activation, and brain injury. Intriguingly, further study revealed that ONOO induced tyrosine nitration of Drp1 peptide, which might contribute to mitochondrial recruitment of Drp1 for mitophagy activation. In vitro cell experiments yielded consistent results with in vivo animal experiments. Taken together, all above findings support the hypothesis that ONOO-induced mitophagy activation aggravates cerebral I/R injury via recruiting Drp1 to damaged mitochondria.

Eugenol Attenuates Cerebral Ischemia-Reperfusion Injury by Enhancing Autophagy via AMPK-mTOR-P70S6K Pathway

“…All these studies revealed that autophagy plays neuroprotective roles after cerebral I/R injury. Reports also demonstrate that autophagy is deleterious for ischemic brain (Zhou et al, 2017;Feng et al, 2018). This discrepancy might be caused by different animal strains, ischemic models, and time of ischemia.…”

Autophagy-dependent cell death – where, how and why a cell eats itself to death

“…Since systemic KOs of non-redundant Atg genes are lethal (Kuma et al, 2017), and even tissue-specific KOs lead to pathology (e.g. Koike et al, 2008), in order to show the necessity of autophagy for cell loss, researchers have resorted to non-specific drugs such as the phosphatidylinositol 3-kinase (PI3K) inhibitor 3-MA (Wen et al, 2008;Puyal et al, 2009;Feng et al, 2018), or less efficient lentiviral-based shRNAmediated knockdowns (Matsui et al, 2007;Zheng et al, 2009;Ginet et al, 2014). Furthermore, the read-out is overall loss of viable tissue (i.e.…”

“…Another recent study has provided evidence for mitophagy in infarcted tissue from adult rats following cerebral ischemia-reperfusion injury. Notably, infarct size was reduced by administration of either the non-specific autophagy inhibitor 3-MA, or a specific inhibitor of Drp1, a factor that is necessary for mitochondrial fission and the recruitment of the mitophagy regulators PINK1 and Parkin to the mitochondria (Feng et al, 2018). Of note, as it is much more difficult to demonstrate mitophagy in vivo, and, furthermore, to prove that it specifically causes cell death, there are not many unambiguous examples in the literature of lethal mitophagy in pathophysiological scenarios.…”

Role of Mitophagy in Cardiovascular Disease

“…Tunicamycin and thapsigargin-induced ER stress protects against ischemic stroke injury, which is probably involved in mitophagy induction [178]. Peroxynitrite-induced PINK1/Parkin-mediated mitophagy activation through drp1 recruitment to damaged mitochondria aggravates cerebral I/R injury during stroke [179]. A natural antioxidant naringin potentially inhibits peroxynitritemediated mitophagy activation by inhibiting the translocation of Parkin to the mitochondria and attenuating ischemic stroke injury [180].…”