Disruption of auto-inhibition underlies conformational signaling of ASIC1a to induce neuronal necroptosis

Jing-Jing Wang,Qin Hu,Fan Yang,Xin Qi,Tian-Le Xu,Fan Liu,Michael X Zhu,Ying Li,Yi-Zhi Wang

doi:10.1038/s41467-019-13873-0

Abstract

We reported previously that acid-sensing ion channel 1a (ASIC1a) mediates acidic neuronal necroptosis via recruiting receptor-interacting protein kinase 1 (RIPK1) to its C terminus (CT), independent of its ion-conducting function. Here we show that the N-terminus (NT) of ASIC1a interacts with its CT to form an auto-inhibition that prevents RIPK1 recruitment/activation under resting conditions. The interaction involves glutamate residues at distal NT and is disrupted by acidosis. Expression of mutant ASIC1a bearing truncation or glutamate-to-alanine substitutions at distal NT causes constitutive cell death. The NT-CT interaction is further disrupted by N-ethylmaleimide-sensitive fusion ATPase (NSF), which associates with ASIC1a-NT under acidosis, facilitating RIPK1 interaction with ASIC1a-CT. Importantly, a membrane-penetrating synthetic peptide representing the distal 20 ASIC1a NT residues, NT1–20, reduced neuronal damage in both in vitro model of acidotoxicity and in vivo mouse model of ischemic stroke, demonstrating the therapeutic potential of targeting the auto-inhibition of ASIC1a for neuroprotection against acidotoxicity.

Highlights

We reported previously that acid-sensing ion channel 1a (ASIC1a) mediates acidic neuronal necroptosis via recruiting receptor-interacting protein kinase 1 (RIPK1) to its C terminus (CT), independent of its ion-conducting function
We showed that ASIC1a-CT is critical for acidosisinduced cell death, which involves binding and phosphorylating RIPK1
The present study extends our earlier finding that acidosisinduced neuronal death involves an ion conduction-independent conformational coupling between ASIC1a and RIPK1 and consequent activation of necroptotic death[2]

Summary

Introduction

We reported previously that acid-sensing ion channel 1a (ASIC1a) mediates acidic neuronal necroptosis via recruiting receptor-interacting protein kinase 1 (RIPK1) to its C terminus (CT), independent of its ion-conducting function. We recently uncovered that the ion conducting function of ASIC1a is not required for the extracellular acid-induced neuronal cell demise[2] Rather, this acidotoxic effect involves an acidosis-evoked complex formation between ASIC1a and receptor-interacting serine/threonine-protein kinase 1 (RIPK1, known as RIP1), with the latter becoming phosphorylated, eventually leading to a specific type of necrotic cell death, termed necroptosis[2]. Testing synthetic membranepenetrating peptides representing the distal NT of ASIC1a, we identify peptide NT1–20 to offer protection to neurons in both acidosis-induced necroptosis in vitro and a mouse model of ischemic stroke in vivo, providing proof of concept for a neuroprotective strategy against acidotoxicity

Methods

Results

Conclusion