Nitrate-responsive Sialin2 couples stress granule assembly and clearance to maintain neuronal homeostasis.

Abstract

Stress granules (SGs) are phase-separated ribonucleoprotein condensates that support cellular adaptation to acute stress, but how extracellular signals coordinate their assembly and recovery-phase clearance remains unclear. Here, we show that nitrate-responsive Sialin2 coordinates SG homeostasis across the stress cycle. During acute stress, Sialin2 undergoes liquid-liquid phase separation and co-assembles with Ras GTPase-activating protein SH3-domain-binding protein (G3BP)-centered scaffolds to promote SG formation. During recovery, Sialin2 preserves liquid-like SG dynamics and promotes autophagy-linked clearance. Sialin2 loss delays SG resolution, promotes retention of amyotrophic lateral sclerosis (ALS)-linked fused in sarcoma (FUS) and TAR DNA-binding protein 43 (TDP-43) variants, and enhances amyloid precursor protein (APP)-related amyloidogenic output. In an ALS mouse model, nitrate treatment reduces SG-like pathology and neuroinflammation, preserves neuronal integrity, and delays functional decline. Together, these findings define a nitrate-Sialin2 signaling module that couples SG assembly to recovery-phase clearance and links inorganic anion sensing to protection against neurodegeneration.