title: Prevention of muscle disuse atrophy by MG132 proteasome inhibitor.
abstract: BACKGROUND
  Our goal was to determine whether in vivo administration of the proteasome inhibitor MG132 can prevent muscle atrophy caused by hindlimb unloading (HU).
  
  
  METHODS
  Twenty-seven NMRI mice were assigned to a weight-bearing control, a 6-day HU, or a HU+MG132 (1 mg/kg/48 h) treatment group.
  
  
  RESULTS
  Gastrocnemius wasting was significantly less in HU+MG132 mice (-6.7 ± 2.0%) compared with HU animals (-12.6 ± 1.1%, P = 0.011). HU was also associated with an increased expression of MuRF-1 (P = 0.006), MAFbx (P = 0.001), and USP28 (P = 0.027) mRNA, whereas Nedd4, E3α, USP19, and UBP45 mRNA did not change significantly. Increases in MuRF-1, MAFbx, and USP28 mRNA were largely repressed after MG132 administration. β5 proteasome activity tended to increase in HU (+16.7 ± 6.1%, P = 0.086). Neither β1 and β2 proteasome activities nor ubiquitin-conjugated proteins were changed by HU.
  
  
  CONCLUSIONS
  Our results indicate that in vivo administration of MG132 partially prevents muscle atrophy associated with disuse and highlight an unexpected regulation of MG132 proteasome inhibitor on ubiquitin-ligases.
authors.affiliation: Research Group in Muscle and Exercise Physiology, Institute of Neuroscience, Université Catholique de Louvain, Place Pierre de Coubertin 1, Louvain-la-Neuve B-1348, Belgium.
authors.forename: Cecile
authors.initials: C
authors.lastname: Jamart
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Raymackers
authors.forename: Gang
authors.initials: G
authors.lastname: Li An
authors.forename: Louise
authors.initials: L
authors.lastname: Deldicque
authors.forename: Marc
authors.initials: M
authors.lastname: Francaux
mesh_terms: D000818:Animals; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology / Q000627:therapeutic use*; D019417:Hindlimb Suspension / Q000379:methods; D007976:Leupeptins / Q000494:pharmacology / Q000627:therapeutic use*; D008297:Male; D051379:Mice; D009133:Muscular Atrophy / Q000188:drug therapy / Q000201:enzymology; D020966:Muscular Disorders, Atrophic / Q000188:drug therapy* / Q000201:enzymology*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D061988:Proteasome Inhibitors; D011897:Random Allocation
chemical_list: D015853:Cysteine Proteinase Inhibitors; D007976:Leupeptins; D061988:Proteasome Inhibitors; D046988:Proteasome Endopeptidase Complex; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde