García-Ortiz, AlmudenaMartín-Cofreces, Noa B.Ibiza, SalesOrtega, ÁngelIzquierdo-Álvarez, AliciaTrullo, AntonioVictor, Víctor M.Calvo, EnriqueSot, BegoñaMartínez Ruiz, AntonioJesús VázquezFrancisco Sánchez-MadridJuan M. SerradorLaura Machesky2024-04-112024-04-112017-04-101545-788510.1371/journal.pbio.2000653https://hdl.handle.net/20.500.14352/103012T cells are an essential arm of the immunity against the invasion of pathogenic agents in organisms. These specialized cells recognize foreign antigens displayed on the surface of antigen-presenting cells (APC) by means of the T cell receptor (TCR). Early signaling takes place in these cells through the specific clustering of TCRs, which trigger the recruitment of signaling molecules to the immune synapse (IS), a plasma membrane–associated intercellular domain important for T cell activation. In this location, several signaling molecules that include the protein kinase C-θ (PKC-θ) form microclusters that are translocated centripetally towards the center of the IS, following the retrograde movement of actin. In this study, we show that nitric oxide (NO) formed by endothelial nitric oxide synthase (eNOS) regulates the translocation of PKC-θ to the IS, increasing its activation. eNOS can effectively modify β-actin by S-nitrosylation on Cys374, reducing its ability to bind profilin-1 (PFN1)—a protein required for actin polymerization—polymerize and flow from the periphery to the central region of the IS. We propose that eNOS-derived NO controls actin polymerization via S-nitrosylation of actin as one of the major driving forces for the transport of PKC-θ towards the central area of the IS, which is essential for T cell activation.The actin cytoskeleton coordinates the organization of signaling microclusters at the immune synapse (IS); however, the mechanisms involved remain poorly understood. We show here that nitric oxide (NO) generated by endothelial nitric oxide synthase (eNOS) controls the coalescence of protein kinase C-θ (PKC-θ) at the central supramolecular activation cluster (c-SMAC) of the IS. eNOS translocated with the Golgi to the IS and partially colocalized with F-actin around the c-SMAC. This resulted in reduced actin polymerization and centripetal retrograde flow of β-actin and PKC-θ from the lamellipodium-like distal (d)- SMAC, promoting PKC-θ activation. Furthermore, eNOS-derived NO S-nitrosylated β-actinon Cys374 and impaired actin binding to profilin-1 (PFN1), as confirmed with the transnitrosylating agent S-nitroso-L-cysteine (Cys-NO). The importance of NO and the formation of PFN1-actin complexes on the regulation of PKC-θ was corroborated by overexpression of PFN1- and actin-binding defective mutants of β-actin (C374S) and PFN1 (H119E), respectively, which reduced the coalescence of PKC-θ at the c-SMAC. These findings unveil a novel NO-dependent mechanism by which the actin cytoskeleton controls the organization and activation of signaling microclusters at the IS.engjournal articlehttps://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.2000653open access577.1Bioquímica (Farmacia)2302 Bioquímica