title: Indinavir impairs protein synthesis and phosphorylations of MAPKs in mouse C2C12 myocytes.
abstract: Anti-retroviral therapy promotes clinical, immunologic, and virologic improvement in human immunodeficiency virus-infected patients. Whereas this therapy adversely affects carbohydrate and lipid metabolism, the effects of anti-retroviral drugs on muscle protein synthesis and degradation have not been reported. To examine these processes, we treated C2C12 myocytes with increasing concentrations of the protease inhibitor indinavir for 1 or 2 days. Treatment of myocytes with a therapeutic concentration of indinavir (20 microM) for 24 h decreased basal protein synthesis by 18%, whereas a 42% decline was observed after 48 h. A similar decrement, albeit quantitatively smaller, was detected with other protease inhibitors. Indinavir did not alter the rate of proteolysis. Likewise, indinavir did not impair the anabolic effect of insulin-like growth factor-I on protein synthesis. Mechanistically, indinavir decreased the phosphorylation of the S6 ribosomal protein (rpS6), and this reduction was associated with a decreased phosphorylation of p70S6 kinase and p90rsk as well as the upstream regulators ERK1/2 and MEK1/2. Indinavir also decreased the phosphorylation of Mnk1 and its upstream effectors, p38 MAPK and ERK1/2. Indinavir did not affect the phosphorylation of mTOR or 4E-BP1, but it did decrease the amount of the active eukaryotic initiation factor eIF4G-eIF4E complex. In conclusion, indinavir decreased protein synthesis in myocytes. This decrease was associated with the disruption of the ERK1/2 and p38 MAPK pathways and a reduction in both the level of functional eIF4F complex and rpS6 phosphorylation.
authors.affiliation: Department of Cellular and Molecular Physiology, Penn State University College of Medicine, Hershey, Pennsylvania 17033, USA. lqh10@psu.edu
authors.forename: Ly Q
authors.initials: LQ
authors.lastname: Hong-Brown
authors.forename: C Randell
authors.initials: CR
authors.lastname: Brown
authors.forename: Charles H
authors.initials: CH
authors.lastname: Lang
mesh_terms: D000818:Animals; D002455:Cell Division; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D039562:Eukaryotic Initiation Factor-4F / Q000187:drug effects / Q000378:metabolism; D017320:HIV Protease Inhibitors / Q000494:pharmacology*; D019469:Indinavir / Q000494:pharmacology*; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects*; D032342:Muscle Cells / Q000187:drug effects*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000187:drug effects / Q000378:metabolism; D038601:Ribosomal Protein S6 / Q000187:drug effects / Q000378:metabolism; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000187:drug effects / Q000378:metabolism; D038744:Ribosomal Protein S6 Kinases, 90-kDa / Q000187:drug effects / Q000378:metabolism
chemical_list: D039562:Eukaryotic Initiation Factor-4F; D017320:HIV Protease Inhibitors; D047908:Intracellular Signaling Peptides and Proteins; D038601:Ribosomal Protein S6; D019469:Indinavir; C491395:MKNK1 protein, human; C106281:Mknk1 protein, mouse; D017346:Protein Serine-Threonine Kinases; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D038744:Ribosomal Protein S6 Kinases, 90-kDa; D020928:Mitogen-Activated Protein Kinases