title: Autophagy modulates dynamics of connexins at the plasma membrane in a ubiquitin-dependent manner.
abstract: Different pathways contribute to the turnover of connexins, the main structural components of gap junctions (GJs). The cellular pool of connexins targeted to each pathway and the functional consequences of degradation through these degradative pathways are unknown. In this work, we focused on the contribution of macroautophagy to connexin degradation. Using pharmacological and genetic blockage of macroautophagy both in vitro and in vivo, we found that the cellular pool targeted by this autophagic system is primarily the one organized into GJs. Interruption of connexins' macroautophagy resulted in their retention at the plasma membrane in the form of functional GJs and subsequent increased GJ-mediated intercellular diffusion. Up-regulation of macroautophagy alone is not sufficient to induce connexin internalization and degradation. To better understand what factors determine the autophagic degradation of GJ connexins, we analyzed the changes undergone by the fraction of plasma membrane connexin 43 targeted for macroautophagy and the sequence of events that trigger this process. We found that Nedd4-mediated ubiquitinylation of the connexin molecule is required to recruit the adaptor protein Eps15 to the GJ and to initiate the autophagy-dependent internalization and degradation of connexin 43. This study reveals a novel regulatory role for macroautophagy in GJ function that is directly dependent on the ubiquitinylation of plasma membrane connexins.
authors.affiliation: Department of Development and Molecular Biology, Albert Einstein College of Medicine, New York, NY 10461, USA.
authors.forename: Eloy
authors.initials: E
authors.lastname: Bejarano
authors.forename: Henrique
authors.initials: H
authors.lastname: Girao
authors.forename: Andrea
authors.initials: A
authors.lastname: Yuste
authors.forename: Bindi
authors.initials: B
authors.lastname: Patel
authors.forename: Carla
authors.initials: C
authors.lastname: Marques
authors.forename: David C
authors.initials: DC
authors.lastname: Spray
authors.forename: Paulo
authors.initials: P
authors.lastname: Pereira
authors.forename: Ana Maria
authors.initials: AM
authors.lastname: Cuervo
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000818:Animals; D001343:Autophagy; D019556:COS Cells; D002450:Cell Communication; D002451:Cell Compartmentation; D002462:Cell Membrane / Q000378:metabolism* / Q000648:ultrastructure; D002522:Chlorocebus aethiops; D017630:Connexins / Q000378:metabolism*; D004705:Endocytosis; D056827:Endosomal Sorting Complexes Required for Transport / Q000378:metabolism; D017629:Gap Junctions / Q000378:metabolism; D008297:Male; D051379:Mice; D008954:Models, Biological; D041681:NIH 3T3 Cells; D000075702:Nedd4 Ubiquitin Protein Ligases; D010588:Phagosomes / Q000378:metabolism / Q000648:ultrastructure; D059748:Proteolysis; D025801:Ubiquitin / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism; D054875:Ubiquitination
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D017630:Connexins; D056827:Endosomal Sorting Complexes Required for Transport; C082729:Eps15 protein, mouse; D025801:Ubiquitin; D000075702:Nedd4 Ubiquitin Protein Ligases; C000618461:Nedd4l protein, mouse; D044767:Ubiquitin-Protein Ligases