The Research Of SOCE And CAPRI Membrane Translocation

CAPRI is a member of GAPIP4BPfamily, containing four conserved structuraldomains, tandem C2domains (C2A-C2B), a GAP-ralated domian (GRD), apleckstrin homology (PH) domian adjacent to a Bruton’s tyrosine kinase (Btk) motif.Elevated cytosolic calcium binds to CAPRI C2domians and induces CAPRImembrane translocation, thus activate CAPRI GAP activity towards small GTPasesRas and Rap1. Thapsgargin (Tg) induces intracellular calcium level elevation byblocking SERCA pumps of ER and activates SOC channels （Store-OperatedCalcium Channel）. In present study, we investigate whether Tg can induce CAPRImembrane translocation and the relationship between CAPRI membranetranslocation and SOC channels activity in HEK293cells. Our researchdemonstrates that Tg is able to induce CAPRI membrane translocation.Non-specific SOC blocker2-APB, Gd3+and knockdown of endogenous STIM1bysh-STIM1, attenuate CAPRI membrane translocation. Moreover, expression ofconstitutive active form of STIM1(D76A) can incuce CAPRI membranetranslocation even in the absence of Tg stimulation. In primary astrocytes, Tgactivates CAPRI’s GAP enzymatic activity and hydrolyze Rap1-GTP, thus reduceRapGTP forms. While, Gd3+reverse such phenomenon. These results demonstratethat activation of SOC by Tg can induce CAPRI membrane translocation,suggesting SOC is involved in regulation of Ras-MAPK pathway in primaryastrocytes.