Urolithin A‐activated autophagy but not mitophagy protects against ischemic neuronal injury by inhibiting ER stress in vitro and in vivo

Abstract

Aim Mitochondrial autophagy (mitophagy) clears damaged mitochondria and attenuates ischemic neuronal injury. Urolithin A (Uro‐A) activates mitophagy in mammal cells and Caenorhabditis elegans. We explored neuroprotection of Uro‐A against ischemic neuronal injury. Methods Mice were subjected to middle cerebral artery occlusion. The brain infarct and neurological deficit scores were measured. The N2a cells and primary cultured mice cortical neurons were subjected to oxygen‐glucose deprivation and reperfusion (OGD/R). Uro‐A was incubated during OGD/R, and cell injury was determined by MTT and LDH. Autophagosomes were visualized by transfecting mCherry‐microtubule‐associated protein 1 light chain 3 (LC3). The protein levels of LC3‐II, p62, Translocase Of Inner Mitochondrial Membrane 23 (TIMM23), and cytochrome c oxidase subunit 4 isoform 1 (COX4I1) were detected by Western blot. The ER stress markers, activating transcription factor 6 (ATF6) and C/EBP homologous protein (CHOP), were determined by reverse transcription‐polymerase chain reaction (RT‐PCR). Results Urolithin A alleviated OGD/R‐induced injury in N2a cells and neurons and reduced ischemic brain injury in mice. Uro‐A reinforced ischemia‐induced autophagy. Furthermore, Uro‐A‐conferred protection was abolished by 3‐methyladenine, suggesting the requirement of autophagy for neuroprotection. However, mitophagy was not further activated by Uro‐A. Instead, Uro‐A attenuated OGD/R‐induced ER stress, which was abolished by 3‐methyladenosine. Additionally, neuroprotection was reversed by ER stress inducer. Conclusion Urolithin A protected against ischemic neuronal injury by reinforcing autophagy rather than mitophagy. Autophagy activation by Uro‐A attenuated ischemic neuronal death by suppressing ER stress.

Neuroprotective Effects of Pomegranate Juice against Parkinson’s Disease and Presence of Ellagitannins-Derived Metabolite—Urolithin A—In the Brain

“…This finding is in agreement with the previously reported lower neuronal loss observed in rats with I/R injury pretreated with punicalagin [43]. Interestingly, the systemic administration of its metabolite UA has protected mice against ischemic brain injury that correlated with an improved neurological deficit score [44]. Based on this, it seems likely that urolithin A could contribute to the protective effect of PJ-treatment against rotenone-induced neuronal degeneration which results in behavioral improvement.…”

The Metabolite Urolithin-A Ameliorates Oxidative Stress in Neuro-2a Cells, Becoming a Potential Neuroprotective Agent

“…Neuro-2a is a neuroblastoma cell line derived from mice, which has been used because of its ability to produce microtubular proteins. Few works have been done with urolithins using this cell line, but it has been demonstrated that urolithin A protects against ischemic neuronal injury by activating autophagy [29]. This research supports our results on mitochondrial activity, demonstrating that urolithin A is not cytotoxic at this range of physiological concentrations (0.5-50 μM).…”

Proteomic investigation of protein adsorption to cerebral microdialysis membranes in surgically treated intracerebral hemorrhage patients - a pilot study

“…It has been recently shown to have a pleotropic role in the CNS including activation of inflammation, induction of scar formation, promotion of cognitive decline and inhibition of repair [20,21]. Mitochondrial import membrane translocases have an implied role in several neurological disease conditions [22][23][24][25][26]. Another protein found exclusively on the CMD membrane was Aldo-keto reductase 1C2 (AKR1C2) shown previously to be increased in the late stages of Alzheimers Disease [27].…”