ER-to-lysosome Ca²⁺refilling followed by K⁺efflux-coupled store-operated Ca²⁺entry in inflammasome activation and metabolic inflammation

We studied lysosomal Ca²⁺in inflammasome. LPS+palmitic acid (PA) decreased lysosomal Ca²⁺([Ca²⁺]_Lys) and increased [Ca²⁺]_ithrough mitochondrial ROS, which was suppressed inTrpm2-KO macrophages. Inflammasome activation and metabolic inflammation in adipose tissue of high-fat diet (HFD)-fed mice were ameliorated byTrpm2KO. ER→lysosome Ca²⁺refilling occurred after lysosomal Ca²⁺release whose blockade attenuated LPS+PA-induced inflammasome. Subsequently, store-operated Ca²⁺entry (SOCE) was activated whose inhibition suppressed inflammasome. SOCE was coupled with K⁺efflux whose inhibition reduced ER Ca²⁺content ([Ca²⁺]_ER) and impaired [Ca²⁺]_Lysrecovery. LPS+PA activated KCa3.1 channel, a Ca²⁺-activated K⁺channel. Inhibitors of KCa3.1 channel orKcnn4KO reduced [Ca²⁺]_ER, attenuated increase of [Ca²⁺]_ior inflammasome activation by LPS+PA, and ameliorated HFD-induced inflammasome or metabolic inflammation. Lysosomal Ca²⁺release induced delayed JNK and ASC phosphorylation through CAMKII-ASK1. These results suggest a novel role of lysosomal Ca²⁺release sustained by ER→lysosome Ca²⁺refilling and K⁺efflux through KCa3.1 channel in inflammasome activation and metabolic inflammation.