Exogenous Netrin-1 Inhibits Autophagy of Ischemic Brain Tissues and Hypoxic Neurons via PI3K/mTOR Pathway in Ischemic Stroke

Abstract

Background and Objective: Ischemic stroke is a serious disease that endangers human health. How to reduce the damage of neurons in ischemic regions is an urgent problem to be explored. Autophagy is an important pathophysiological process in cerebral ischemia and Netrin-1 is an effective neuroprotective protein. This study aims to investigate the effect of Netrin-1 on autophagy of ischemic brain tissues and hypoxic neurons. Methods: We constructed rat persistent middle cerebral artery occlusion model in vivo and constructed the Oxygen Glucose-Deprivation model in vitro. Rats and cells were treated with or without Netrin-1. Western blot analysis was performed to detect autophagy related proteins LC3B, P62 and pathway related proteins PI3K, p-PI3K, mTOR, p-mTOR. CCK-8 assay was performed to detect the viability of hypoxic neurons. We also performed western-blot analysis and qRT-PCR test to detect levels of Netrin-1 protein and mRNA. Results: Autophagy enhanced both in ischemic brain tissues and hypoxic neurons. Netrin-1 inhibited autophagy through PI3K/mTOR pathway both in vivo and in vitro. At the same time, we found that exogenous Netrin-1 can promote the secretion of Netrin-1 protein by neurons themselves, which indicated that Netrin-1 can further amplify the neuroprotective effect through the positive feedback mechanism. Conclusions: Exogenous Netrin-1 alleviates damage of ischemic brain tissues and enhances viability of hypoxic neurons by inhibiting autophagy via PI3K/mTOR pathway. This effect can be amplified by positive feedback mechanism.

Hypoxic Adaptation of Mitochondrial Metabolism in Rat Cerebellum Decreases in Pregnancy

“…Autophagy is also coupled to pro-survival function of mitochondrial fission under energy stress [44][45][46][47]. However, the homeostatic and pro-survival functions of mTOR, autophagy and mitochondrial fission are highly conditional, with overactivation of these processes also mediating the brain damage by hypoxia [48][49][50].…”

A Novel Netrin-1-Derived Peptide Enhances Protection against Neuronal Death and Mitigates of Intracerebral Hemorrhage in Mice

“…Netrin-1 activates FAK phosphorylation and Src family protein tyrosine kinases (SFKs) phosphorylation [ 17 ]. Both FAK and SFK signaling pathways play a pivotal role in the developmental stage of nervous system and injury repair [ 36 , 37 ]. Moreover, Netrin-1 is able to activate the extracellular signal-regulated kinase-1/2 (ERK1/2), which mediates action of Mitogen-activated protein kinase (MAPK) pathway [ 38 , 39 , 40 ].…”

Treating Cerebral Ischemia: Novel Therapeutic Strategies from Experimental Stroke Research

“…The precise role of autophagy as the third main mechanism of programmed cell death after ischemic stroke is not fully understood and remains controversial (26). However, cumulative evidence from preclinical in vitro and in vivo studies suggests a neuroprotective effect of pharmacological autophagy inhibition (27)(28)(29).…”

“…miR-21 mediates antiinflammatory activity through the downregulation of NF-κB and TNF-α and induction of the antiinflammatory cytokine IL-10 (131). Another miR, miR-126 from ADMSC-EVs, can promote functional recovery after stroke in rats by improving neurogenesis and suppressing microglia activation (27). Meanwhile, Gal-3BP, a suppressor of inflammatory responses through NF-κB pathway, was found in iPSC-EVs.…”