title: UBE2B is implicated in myofibrillar protein loss in catabolic C2C12 myotubes.
abstract: Skeletal muscle protein loss is an adaptive response to various patho-physiological situations, and the ubiquitin proteasome system (UPS) is responsible for the degradation of the bulk of muscle proteins. The role of E2 ubiquitin-conjugating enzymes is still poorly understood in skeletal muscle.
  
  
  
  We screened for E2s expression levels in C2C12 myotubes submitted to the catabolic glucocorticoid dexamethasone (Dex).
  
  
  
  One micromolar Dex induced an accumulation of proteasome substrates (polyUb conjugates) and an overexpression of the muscle-specific E3 ligase MuRF1 and of six E2 enzymes, UBE2A, UBE2B, UBE2D1, UBE2D2, UBE2G1, and UBE2J1. However, only MuRF1 and UBE2B were sensitive to mild catabolic conditions (0.16 μM Dex). UBE2B knockdown induced a sharp decrease of total (-18%) and K48 (-28%) Ub conjugates, that is, proteasome substrates, indicating an important role of UBE2B in the overall protein breakdown in catabolic myotubes.
  
  
  
  Interestingly, these results indicate an important role of UBE2B on muscle protein homeostasis during catabolic conditions.
authors.affiliation: INRA, UMR 1019, UNH, CRNH Auvergne Saint Genès Champanelle F-63122 France; Clermont Université, Université d'Auvergne, Unité de Nutrition Humaine BP 10448 Clermont-Ferrand F-63000 France.
authors.forename: Cécile
authors.initials: C
authors.lastname: Polge
authors.affiliation: INRA, UMR 1019, UNH, CRNH Auvergne Saint Genès Champanelle F-63122 France; Clermont Université, Université d'Auvergne, Unité de Nutrition Humaine BP 10448 Clermont-Ferrand F-63000 France.
authors.forename: Roza
authors.initials: R
authors.lastname: Leulmi
authors.affiliation: INRA, UMR 1019, UNH, CRNH Auvergne Saint Genès Champanelle F-63122 France; Clermont Université, Université d'Auvergne, Unité de Nutrition Humaine BP 10448 Clermont-Ferrand F-63000 France.
authors.forename: Marianne
authors.initials: M
authors.lastname: Jarzaguet
authors.affiliation: INRA, UMR 1019, UNH, CRNH Auvergne Saint Genès Champanelle F-63122 France; Clermont Université, Université d'Auvergne, Unité de Nutrition Humaine BP 10448 Clermont-Ferrand F-63000 France.
authors.forename: Agnes
authors.initials: A
authors.lastname: Claustre
authors.affiliation: INRA, UMR 1019, UNH, CRNH Auvergne Saint Genès Champanelle F-63122 France; Clermont Université, Université d'Auvergne, Unité de Nutrition Humaine BP 10448 Clermont-Ferrand F-63000 France.
authors.forename: Lydie
authors.initials: L
authors.lastname: Combaret
authors.affiliation: INRA, UMR 1019, UNH, CRNH Auvergne Saint Genès Champanelle F-63122 France; Clermont Université, Université d'Auvergne, Unité de Nutrition Humaine BP 10448 Clermont-Ferrand F-63000 France.
authors.forename: Daniel
authors.initials: D
authors.lastname: Béchet
authors.affiliation: INRA, UMR 1019, UNH, CRNH Auvergne Saint Genès Champanelle F-63122 France; Clermont Université, Université d'Auvergne, Unité de Nutrition Humaine BP 10448 Clermont-Ferrand F-63000 France; Service de Néphrologie Réanimation Médicale, Pôle Respiratoire, Endocrinologie-Diabétologie, Urologie, Néphrologie-Dialyse, Nutrition Clinique, Infectiologie, Réanimation Médicale, Hygiène Hospitalière (REUNNIRH) Clermont-Ferrand France.
authors.forename: Anne-Elisabeth
authors.initials: AE
authors.lastname: Heng
authors.affiliation: INRA, UMR 1019, UNH, CRNH Auvergne Saint Genès Champanelle F-63122 France; Clermont Université, Université d'Auvergne, Unité de Nutrition Humaine BP 10448 Clermont-Ferrand F-63000 France.
authors.forename: Didier
authors.initials: D
authors.lastname: Attaix
authors.affiliation: INRA, UMR 1019, UNH, CRNH Auvergne Saint Genès Champanelle F-63122 France; Clermont Université, Université d'Auvergne, Unité de Nutrition Humaine BP 10448 Clermont-Ferrand F-63000 France.
authors.forename: Daniel
authors.initials: D
authors.lastname: Taillandier
keywords: C2C12 myotubes; E2 Ubiquitin‐conjugating enzyme; E3 ligase; Ubiquitin; Ubiquitin proteasome system