Biology subjects

Blouin, C. M.

Publications and source records attributed to Blouin, C. M..

3 recordsLinked to original sources

bioRxiv2023

Dia2 formin controls receptor activity by organizing plasma membrane lipid partitioning at the nanoscale

Activation of JAK/STAT signaling by IFN-{gamma} requires partitioning of IFN-{gamma}R into specific lipid nanodomains at the plasma membrane. Using IFN-{gamma}R as a proxy, we investigated the role of actin dynamics in the formation and organization of lipid nanodomains, a process that remains poorly understood. We identified formin Dia2/DIAPH3 as a specific and RhoA -dependent regulator of IFN-{gamma}-induced JAK/STAT signaling. Based on lipidomics and specific probes enabling membrane lipid imaging by super resolution microscopy, we demonstrate that Dia2 is required for proper assembly of sphingomyelin and cholesterol lipid complexes. Finally, we show that the disorganization of lipid nanodomains induced by Dia2 depletion results in drastic changes in nano-partitioning and activity of other membrane proteins, such as Thy1 and PD-L1. Our data establish, therefore, the central role of the RhoA-Dia2 axis in the regulation of IFN-{gamma} induced JAK/STAT signaling, and more broadly, in the nanoscale organization of the plasma membrane.

cell biology↗

bioRxiv2019

STAM Interaction with Hrs Controls JAK/STAT Activation by Interferon-α at the Early Endosome

Activation of the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway by type I interferons (IFN) requires clathrin-dependent endocytosis of the IFN-/{beta} receptor (IFNAR). The molecular machinery that brings about the selective activation of IFN-/{beta}-induced JAK/STAT signaling on endosomes remains unknown. Here we show that the constitutive association of STAM with IFNAR1 and the TYK2 Janus kinase at the plasma membrane prevents the activation of TYK2 by type I IFNs. IFN- stimulated endocytosis leads to the interaction of IFNAR1 with Hrs on early endosomes, which then relieves TYK2 inhibition by STAM and thereby allows for TYK2 and IFNAR signaling. In contrast, IFN-{beta} stimulation results in sorting of IFNAR to a distinct endosomal subdomain where the receptor is activated independently from Hrs. Our results identify the molecular machinery that controls the spatiotemporal activation of TYK2 and establish the central role of endosomal sorting in the differential regulation of JAK/STAT signaling by IFN- and IFN-{beta}.\n\nSummaryThe spatiotemporal activation of JAK/STAT signaling by IFN- is controlled by STAM association with Hrs at the early endosome.

cell biology↗

bioRxiv2018

Lack of functional caveolae in Cav3 mutated human dystrophic myotubes results in deficient mechanoprotection and IL6/STAT3 mechanosignaling.

Caveolin-3 is the major structural protein of caveolae in muscle cells. Mutations in the CAV3 gene cause different type of muscle disorders mostly characterized by defects in membrane integrity and repair, deregulation in the expression of various muscle proteins and deregulation of several muscle associated signaling pathways. We show here that myotubes derived from patients bearing the CAV3 P28L and R26Q mutations present a lack of functional caveolae at the plasma membrane which results in an abnormal mechanoresponse. Mutant myotubes can no longer buffer the increase of membrane tension induced by mechanical stress and present an hyperactivation of the IL6/STAT3 signaling pathway at rest and under mechanical stress. The impaired mechanical regulation of the IL6/STAT3 signaling pathway by caveolae leads to chronic activation and a higher expression of muscle specific genes. These defects could be reversed by reassembling a pool of functional caveolae through expression of wild type Cav3. Our findings bring more mechanistic insight into human Cav3 associated muscle disorders and show a general defect in the mechanoresponse of CAV3 P28L and R26Q myotubes.

cell biology↗