GPCR-mediated Activation of PLCγ2 Initiates Dysregulated Recruitment of Neutrophils in Cold-induced Urticaria in PLAID Patients

The current dogma is that chemoattractants G protein coupled receptors (GPCRs) activate β phospholipase C (PLCβ) while receptor tyrosine kinases (RTKs) activate γ phospholipase C (PLCγ). Here, we show that chemoattractant/GPCR-mediated membrane recruitment of PLCγ2 constitutes GPCR-mediated phospholipase C (PLC) signaling and is essential for neutrophil polarization and migration during GPCR-mediated chemotaxis. In response to a chemoattractant stimulation, cells lacking PLCγ2 ( plcg2 kd ) displayed altered dynamics of diacylglycerol (DAG) production and calcium response; increased Ras/PI3K/Akt activation; elevated GSK3 phosphorylation and cofilin activation; impaired dynamics of actin polymerization; and consequently defects in cell polarization and migration during chemotaxis. At low temperature, neutrophils expressing the gain-of-function mutant of PLCγ2 (Δ686) displayed better chemotaxis than the cells expressing wild-type PLCγ2. The study provides a molecular mechanism for the dysregulated recruitment and activation of neutrophils in cold-induced urticaria in PLCγ2-associated antibody deficiency and immune dysregulation (PLAID) patients bearing gain-of-function mutations of PLCγ2.