title: Lack of Smad3 signaling leads to impaired skeletal muscle regeneration.
abstract: Smad3 is a key intracellular signaling mediator for both transforming growth factor-β and myostatin, two major regulators of skeletal muscle growth. Previous published work has revealed pronounced muscle atrophy together with impaired satellite cell functionality in Smad3-null muscles. In the present study, we have further validated a role for Smad3 signaling in skeletal muscle regeneration. Here, we show that Smad3-null mice had incomplete recovery of muscle weight and myofiber size after muscle injury. Histological/immunohistochemical analysis suggested impaired inflammatory response and reduced number of activated myoblasts during the early stages of muscle regeneration in the tibialis anterior muscle of Smad3-null mice. Nascent myofibers formed after muscle injury were also reduced in number. Moreover, Smad3-null regenerated muscle had decreased oxidative enzyme activity and impaired mitochondrial biogenesis, evident by the downregulation of the gene encoding mitochondrial transcription factor A, a master regulator of mitochondrial biogenesis. Consistent with known Smad3 function, reduced fibrotic tissue formation was also seen in regenerated Smad3-null muscle. In conclusion, Smad3 deficiency leads to impaired muscle regeneration, which underscores an essential role of Smad3 in postnatal myogenesis. Given the negative role of myostatin during muscle regeneration, the increased expression of myostatin observed in Smad3-null muscle may contribute to the regeneration defects.
authors.affiliation: School of Biological Sciences, Nanyang Technological University, Singapore.
authors.forename: Xiaojia
authors.initials: X
authors.lastname: Ge
authors.forename: Anuradha
authors.initials: A
authors.lastname: Vajjala
authors.forename: Craig
authors.initials: C
authors.lastname: McFarlane
authors.forename: Walter
authors.initials: W
authors.lastname: Wahli
authors.forename: Mridula
authors.initials: M
authors.lastname: Sharma
authors.forename: Ravi
authors.initials: R
authors.lastname: Kambadur
mesh_terms: D000818:Animals; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005355:Fibrosis; D005786:Gene Expression Regulation; D008264:Macrophages / Q000276:immunology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D008931:Mitochondria, Muscle / Q000378:metabolism; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D018482:Muscle, Skeletal / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D009133:Muscular Atrophy / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D032448:Myoblasts, Skeletal / Q000201:enzymology / Q000378:metabolism / Q000473:pathology; D018006:Myogenic Regulatory Factors / Q000235:genetics / Q000378:metabolism; D055435:Myostatin / Q000235:genetics / Q000378:metabolism; D009336:Necrosis; D020556:Neutrophil Infiltration; D012333:RNA, Messenger / Q000378:metabolism; D032496:Satellite Cells, Skeletal Muscle / Q000201:enzymology / Q000378:metabolism / Q000473:pathology; D015398:Signal Transduction; D051900:Smad3 Protein / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D004268:DNA-Binding Proteins; D024101:Mitochondrial Proteins; C525912:Mstn protein, mouse; D018006:Myogenic Regulatory Factors; D055435:Myostatin; D012333:RNA, Messenger; D051900:Smad3 Protein; C497791:Smad3 protein, mouse; D014157:Transcription Factors; C422562:mitochondrial transcription factor A