P2X7 Receptor Activation Modulates Autophagy in SOD1-G93A Mouse Microglia

Abstract

Autophagy and inflammation play determinant roles in the pathogenesis of Amyotrophic Lateral Sclerosis (ALS), an adult-onset neurodegenerative disease characterized by deterioration and final loss of upper and lower motor neurons (MN) priming microglia to sustain neuroinflammation and a vicious cycle of neurodegeneration. Given that extracellular ATP through P2X7 receptor constitutes a neuron-to-microglia alarm signal implicated in ALS, and that P2X7 affects autophagy in immune cells, we have investigated if autophagy can be directly triggered by P2X7 activation in primary microglia from superoxide dismutase 1 (SOD1)-G93A mice. We report that P2X7 enhances the expression of the autophagic marker microtubule-associated protein 1 light chain 3 (LC3)-II, via mTOR pathway and concomitantly with modulation of anti-inflammatory M2 microglia markers. We also demonstrate that the autophagic target SQSTM1/p62 is decreased in SOD1-G93A microglia after a short stimulation of P2X7, but increased after a sustained challenge. These effects are prevented by the P2X7 antagonist A-804598, and the autophagy/phosphoinositide-3-kinase inhibitor wortmannin (WM). Finally, a chronic in vivo treatment with A-804598 in SOD1-G93A mice decreases the expression of SQSTM1/p62 in lumbar spinal cord at end stage of disease. These data identify the modulation of the autophagic flux as a novel mechanism by which P2X7 activates ALS-microglia, to be considered for further investigations in ALS.

P2X7R-mediated Autophagic Impairment Contributes to Central Sensitization in a chronic Migraine Model with Recurrent Nitroglycerin Stimulation in Mice

“…All the data are presented as the mean ± standard error of the mean (SEM [59,60]. The accumulation of LC3-II is usually caused by increased autophagosome formation due to enhanced autophagic ux or dysfunctional degradation of the autophagosome due to impaired autophagic ux [36,45,61,62]. The p62 protein is a well-known autophagy substrate that helps to determine the reason for the change in LC3-II, thus providing the additional evidence of autophagic ux [59].…”

“…It is well documented that P2 × 7R plays a dual role in autophagy pathway regulation depending on the different cell types and stimulation window of P2 × 7R [36]. In non-transgenic microglia and human epithelial cells, P2 × 7R negatively regulates autophagy by disrupting lysosomal function [32,113,114].…”

“…Numerous studies have indicated the involvement role of P2X7R in autophagy regulation [32,33]. Shortterm P2X7R activation has been shown to stimulate autophagic ux, while persistent P2X7R stimulation leads to autophagic dysfunction [36]. Here, we assessed the effect of P2X7R on autophagic ux in the CM.…”

“…Numerous studies have indicated the critical role of P2 × 7R in autophagy regulation [32][33][34][35][36][37]. The P2 × 7R-mediated autophagy modulation has been con rmed to participate in the pathophysiological process of amyotrophic lateral sclerosis [36], Duchenne muscular dystrophy [37] and status epilepticus [35]. Meanwhile, extensive evidence has revealed the interaction between autophagy and in ammatory processes [38].…”

Protein Kinase C Isozymes and Autophagy during Neurodegenerative Disease Progression

“…ATG7 cKO; SOD1G93A double mutant mice show a reduction in p62 accumulation and interestingly prolong the lifespan of mice [132]. P2X7 overexpression encourages autophagic protein in SOD1G93A primary microglia and causes formation of ALS pathogenesis [133]. On the other hand, rilmenidine, disseminates the autophagy mechanism through the mTOR independent pathway and induces the degradation of SOD1G93A and p62 aggregates.…”