title: Myostatin and MyoD family expression in skeletal muscle of IGF-1 knockout mice.
abstract: Insulin-like growth factor-1 (IGF-1) is a positive regulator in proliferation and differentiation of skeletal muscle cells, while myostatin (MSTN) is a member of transforming growth factor beta superfamily that acts as a negative regulator of skeletal muscle mass. The present study was performed to detail whether a correlation exists between MSTN and IGF-1 in skeletal muscle of IGF-1 knockout mice (IGF-1(-/-)) and their wild type (WT; i.e., IGF-1(+/+)) littermates. The body weight of IGF-1(-/-) animals was 32% that of WT littermates. The fiber cross-sectional areas (CSA) and number of fibers in M. rectus femoris of IGF-1(-/-) animals were 49 and 59% those of WT animals, respectively. Thus, muscle hypoplasia of IGF-1(-/-) undoubtedly was confirmed. Myostatin mRNA levels and protein levels were similar between M. gastrocnemius of IGF-1(-/-) and WT animals. Myostatin immunoreactivity was similarly localized in muscle fibers of both IGF-1(-/-) and WT M. rectus femoris. The mRNA levels of MyoD family (Myf5, MyoD, MRF4, myogenin) were differentially expressed in IGF-1(-/-)M. gastrocnemius, in which the mRNA expression of MRF4 and myogenin was significantly lower, whereas there were no changes in the mRNA expression of Myf5 and MyoD. These findings first describe that myostatin expression is not influenced by intrinsic failure of IGF-1, although MRF4 and myogenin are downregulated.
authors.affiliation: Laboratory of Functional Morphology, Department of Animal Biology, Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai 981-8555, Japan.
authors.forename: Masato
authors.initials: M
authors.lastname: Miyake
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Hayashi
authors.forename: Tomomi
authors.initials: T
authors.lastname: Sato
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Taketa
authors.forename: Kouichi
authors.initials: K
authors.lastname: Watanabe
authors.forename: Shinji
authors.initials: S
authors.lastname: Hayashi
authors.forename: Sachi
authors.initials: S
authors.lastname: Tanaka
authors.forename: Shyuichi
authors.initials: S
authors.lastname: Ohwada
authors.forename: Hisashi
authors.initials: H
authors.lastname: Aso
authors.forename: Takahiro
authors.initials: T
authors.lastname: Yamaguchi
mesh_terms: D000818:Animals; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000502:physiology*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000378:metabolism*; D017570:MyoD Protein / Q000235:genetics / Q000378:metabolism*; D051787:Myogenic Regulatory Factor 5 / Q000235:genetics / Q000378:metabolism; D018006:Myogenic Regulatory Factors / Q000235:genetics / Q000378:metabolism; D018008:Myogenin / Q000235:genetics / Q000378:metabolism; D055435:Myostatin; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism*
chemical_list: C525912:Mstn protein, mouse; D017570:MyoD Protein; C057363:MyoD1 myogenic differentiation protein; C503801:Myog protein, mouse; D051787:Myogenic Regulatory Factor 5; D018006:Myogenic Regulatory Factors; D018008:Myogenin; D055435:Myostatin; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; C063403:myogenic factor 6; D007334:Insulin-Like Growth Factor I