title: Myostatin promotes a fibrotic phenotypic switch in multipotent C3H 10T1/2 cells without affecting their differentiation into myofibroblasts.
abstract: Tissue fibrosis, the excessive deposition of collagen/extracellular matrix combined with the reduction of the cell compartment, defines fibroproliferative diseases, a major cause of death and a public health burden. Key cellular processes in fibrosis include the generation of myofibroblasts from progenitor cells, and the activation or switch of already differentiated cells to a fibrotic synthetic phenotype. Myostatin, a negative regulator of skeletal muscle mass, is postulated to be involved in muscle fibrosis. We have examined whether myostatin affects the differentiation of a multipotent mesenchymal mouse cell line into myofibroblasts, and/or modulates the fibrotic phenotype and Smad expression of the cell population. In addition, we investigated the role of follistatin in this process. Incubation of cells with recombinant myostatin protein did not affect the proportion of myofibroblasts in the culture, but significantly upregulated the expression of fibrotic markers such as collagen and the key profibrotic factors transforming growth factor-beta1 (TGF-beta1) and plasminogen activator inhibitor (PAI-1), as well as Smad3 and 4, and the pSmad2/3. An antifibrotic process evidenced by the upregulation of follistatin, Smad7, and matrix metalloproteinase 8 accompanied these changes. Follistatin inhibited TGF-beta1 induction by myostatin. Transfection with a cDNA expressing myostatin upregulated PAI-1, whereas an shRNA against myostatin blocked this effect. In conclusion, myostatin induced a fibrotic phenotype without significantly affecting differentiation into myofibroblasts. The concurrent endogenous antifibrotic reaction confirms the view that phenotypic switches in multipotent and differentiated cells may affect the progress or reversion of fibrosis, and that myostatin pharmacological inactivation may be a novel therapeutic target against fibrosis.
authors.affiliation: Division of Endocrinology Metabolism and Molecular Medicine and RCMI Molecular Core, The Charles R Drew University of Medicine and Science, 1731 East 120th Street, Los Angeles, California, 90059 USA. jorgeartaza@cdrewu.edu
authors.forename: Jorge N
authors.initials: JN
authors.lastname: Artaza
authors.forename: Rajan
authors.initials: R
authors.lastname: Singh
authors.forename: Monica G
authors.initials: MG
authors.lastname: Ferrini
authors.forename: Melissa
authors.initials: M
authors.lastname: Braga
authors.forename: James
authors.initials: J
authors.lastname: Tsao
authors.forename: Nestor F
authors.initials: NF
authors.lastname: Gonzalez-Cadavid
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D015536:Down-Regulation; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology*; D005355:Fibrosis; D038681:Follistatin / Q000378:metabolism / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D008648:Mesoderm / Q000187:drug effects / Q000473:pathology*; D051379:Mice; D039902:Multipotent Stem Cells / Q000473:pathology*; D032446:Myoblasts / Q000378:metabolism / Q000473:pathology*; D055435:Myostatin; D010641:Phenotype; D010766:Phosphorylation; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D051785:Smad Proteins / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D053773:Transforming Growth Factor beta1 / Q000235:genetics; D015854:Up-Regulation
chemical_list: D038681:Follistatin; C525912:Mstn protein, mouse; D055435:Myostatin; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D011994:Recombinant Proteins; D051785:Smad Proteins; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1