Akbal, A. | bioRxiv Science

bioRxiv2026

NLRP3 activators disrupt the endocytic AP2 complex and plasma membrane signaling

Organellar perturbations are linked to NLRP3 inflammasome activation, however, it remains unclear whether unrelated agonists converge on a common upstream pathway. Here, we traced intracellular organelle and protein movements by differential ultracentrifugation combined with mass spectrometry-based proteomics. We show that NLRP3 activators uniformly disrupt the endocytic Adaptor Protein 2 (AP2) complex, whereas other subcellular rearrangements are stimulus-specific. We discovered Dynasore as a K-efflux-independent NLRP3 activator that engages this signaling node irrespective of endocytosis inhibition. Pharmacological and genetic perturbation of AP2 renders cells unresponsive to extracellular cues, blunting GPCR signaling, cAMP production, and chemotaxis, thereby enforcing a frozen signaling state that propagates NLRP3 inflammasome activation. Collectively, our study reveals a common surveillance checkpoint linking impaired plasma membrane signaling to the execution of inflammation and cell death. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/707400v1_ufig1.gif" ALT="Figure 1"> View larger version (44K): org.highwire.dtl.DTLVardef@178eb1dorg.highwire.dtl.DTLVardef@193cb02org.highwire.dtl.DTLVardef@1f50080org.highwire.dtl.DTLVardef@1f3e3e4_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2024

Cytosolic sodium accumulation is a cellular danger signal triggering endocytic dysfunction and NLRP3 inflammasome activation

Detecting and responding to noxious molecules internalized within the endolysosomal system, including bacterial toxins and particulate matter, is essential to prevent cellular intoxication and damage. Here, we demonstrate that the NLRP3 inflammasome detects perturbations of the endolysosomal system by large clostridial toxins, including toxin B from Clostridioides difficile, as well as monosodium urate and silica crystals in human macrophages. These molecules cause sodium efflux from the endolysosomal system into the cytosol, driving cytosolic sodium accumulation. The rapid increase in cytosolic sodium subsequently triggers cell swelling and inhibits endocytic trafficking to activate the NLRP3 inflammasome. Furthermore, we demonstrate that cytosolic sodium accumulation is a common trigger for NLRP3 activation by non-particulate stimuli, including nigericin and inhibition of the Na+/K+ ATPase. Our findings reveal that accumulation of cytosolic sodium is the common denominator underlying activation of the NLRP3 inflammasome upon exposure to different danger signals.

immunology↗