Chloride intracellular channel (CLIC) protein function in S1P-induced Rac1 activation requires membrane localization of the C-terminus, but not thiol-transferase nor ion channel activities

• DOI: 10.3389/fcell.2025.1565262
• Publication Date: 2025-04-01T05:53:41Z
• Authors: De Yu Mao; Jordan J. Jesse; Daniel D. Shaye; Jan Kitajewski
• Keywords: Transport protein

We have established a novel and evolutionarily-conserved function for chloride intracellular channel proteins (CLICs) in regulating Rho/Rac GTPases downstream of G protein-coupled receptors (GPCRs). Endothelial CLIC1 CLIC4 are rapidly transiently re-localized from the cytoplasm to plasma membrane response GPCR ligand sphingosine-1-phosphate (S1P), both CLICs required activate Rac1 S1P, but how they perform this remains unknown. Biochemical studies suggest that act as non-specific ion channels and/or glutathione-S-transferases, dependent on N-terminal features, vitro. Here we investigate CLIC functional domains localization requirements their S1P-mediated signaling. Structure-function analyses endothelial cells demonstrate CLIC4-specific functions reside at C-termini, N-terminus encodes determinants S1P-induced re-localization is dispensable activation when C-terminus localized via heterologous signal. Our results postulated thiol-transferase activities not suggests sequences C-termini critical function. Given importance S1P signaling vascular biology disease, our work establishes platform further understanding membrane-localized link activity regulation.