Gasdermin-Driven Cell Death and Immune Activation in Parkinson's Disease

摘要

Abstract Cell death and inflammation in the substantia nigra are well established hallmarks of Parkinson’s disease (PD). However, the molecular mechanisms governing these processes are still poorly understood. Pyroptosis is an inflammatory necrosis driven by the gasdermin (GSDM) family proteins. When cleaved intracellularly by caspases, gasdermins form pores in cell membranes which first act as conduits for cytokine secretion and ultimately may cause cell swelling and overt necrosis. An emerging body of literature suggests that gasdermin- driven pyroptosis is a key molecular event in initiating cell death and innate immune activation. While the majority of GSDM studies have focused on immune, epithelial and cancer cells, our preliminary data shows that two family members, GSDME (DFNA5) and GSDMD, are expressed in the CNS. We have found that GSDME is present in neurons, while GSDMD is enriched in microglia. The role of these cell death proteins in CNS pathology has not yet been studied. The objective of this proposal is to characterize how the gasdermins may control cell death and inflammation in PD. I hypothesize that in the context of PD a) GSDME acts in neurons to drive pyroptotic neuronal cell death, while b) GSDMD acts in microglia to promote cytokine secretion. To test these hypotheses, we will use mechanistic in vitro experiments, in vivo studies of GSDM expression, and GSDME and D -/- transgenic mice in common PD models. Preliminary data shows that knockout of GSDME protects a human neuron-like cell line (SH-SY5Y) from pyroptosis induced by PD-causing neurotoxins including 6-OHDA, rotenone and MPP. In Aim 1, we will extend these results and investigate whether GSDME is necessary for neurotoxin (6-OHDA) and alpha-synuclein-induced cell death in primary midbrain neurons and two in vivo mouse models of PD. Aim 2 will explore whether GSDMD is cleaved in neurotoxin and alpha-synuclein induced microglia changes, and if this molecule is necessary for cell death and cytokine secretion in vitro and in vivo. Collectively, we seek to establish whether the evolutionarily conserved gasdermin pathways are active in the CNS and contribute to PD. This proposed work has broad implications for how innate immune axes drive neuronal injury and inflammation and may provide rationale for trialing novel GSDM inhibitors in neurodegenerative disease.