title: Suppressor of cytokine signaling 1 suppresses muscle differentiation through modulation of IGF-I receptor signal transduction.
abstract: Suppressor of cytokine signaling (SOCS) 1 was initially identified as an intracellular negative feedback regulator of the JAK-STAT signal pathway. Recently, it has been suggested that SOCS1 affects signals of growth factors and hormones. One of them, SOCS1, is also known to be involved in auto-regulation of IRS-1-mediated signaling. However, the mechanism(s) of SOCS1 induction by insulin-like growth factor (IGF)-I and a role of SOCS1 on IGF-I receptor-mediated signaling are not clarified. Here, we investigate SOCS1 on muscle differentiation. We found that muscle differentiation was suppressed in SOCS1 stable transformant C2C12 myoblasts, while it was promoted in SOCS1-deficient myoblasts. Additionally, SOCS1 augmented MEK phosphorylation and reduced Akt phosphorylation induced by IGF-I. Then, SOCS1 stable transformant C2C12 myoblasts, infected with adenovirus bearing constitutively active Akt, have the ability to differentiate again. Collectively, these findings suggest that SOCS1 suppresses muscle differentiation through negative feedback regulation of IGF-I receptor-mediated signaling.
authors.affiliation: Department of Molecular Medicine, Osaka University Graduate School of Medicine, 2-2 Yamada-oka, Suita City, Osaka, Japan.
authors.forename: Makiko
authors.initials: M
authors.lastname: Inaba
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Saito
authors.forename: Minoru
authors.initials: M
authors.lastname: Fujimoto
authors.forename: Satoru
authors.initials: S
authors.lastname: Sumitani
authors.forename: Tomoharu
authors.initials: T
authors.lastname: Ohkawara
authors.forename: Toshio
authors.initials: T
authors.lastname: Tanaka
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Kouhara
authors.forename: Soji
authors.initials: S
authors.lastname: Kasayama
authors.forename: Ichiro
authors.initials: I
authors.lastname: Kawase
authors.forename: Tadamitsu
authors.initials: T
authors.lastname: Kishimoto
authors.forename: Tetsuji
authors.initials: T
authors.lastname: Naka
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation / Q000502:physiology*; D002460:Cell Line; D005786:Gene Expression Regulation / Q000502:physiology; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D051379:Mice; D018485:Muscle Fibers, Skeletal / Q000166:cytology* / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism; D032446:Myoblasts / Q000166:cytology* / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D017526:Receptor, IGF Type 1 / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D000071222:Suppressor of Cytokine Signaling 1 Protein; D050826:Suppressor of Cytokine Signaling Proteins
chemical_list: D002352:Carrier Proteins; D011518:Proto-Oncogene Proteins; D011994:Recombinant Proteins; D012097:Repressor Proteins; C491590:Socs1 protein, mouse; D000071222:Suppressor of Cytokine Signaling 1 Protein; D050826:Suppressor of Cytokine Signaling Proteins; D007334:Insulin-Like Growth Factor I; D017526:Receptor, IGF Type 1; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt