Research Communication Transforming growth factor type- b inhibits Mas receptor expression in fibroblasts but not in myoblasts or differentiated myotubes; Relevance to fibrosis associated to muscular dystrophies Catalina Cofre 1 Mar  ıa Jos e Acu~ na 1 Osvaldo Contreras 1 Mar  ıa Gabriela Morales 2 Cecilia Riquelme 1 Claudio Cabello-Verrugio 2 Enrique Brandan 1 * 1 Center for Aging and Regeneration, CARE Chile-UC and Department of Cell and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Cat  olica de Chile, Santiago, Chile 2 Laboratorio de Biolog  ıa y Fisiopatolog  ıa Molecular, Departamento de Ciencias Biol  ogicas, Facultad de Ciencias Biol  ogicas & Facultad de Medicina, Universidad Andr  es Bello, Santiago, Chile Abstract Duchenne muscular dystrophy is a genetic disorder character- ized by myofiber degeneration, muscle weakness, and increased fibrosis. Transforming growth factor type-b (TGF-b), a central mediator of fibrosis, is upregulated in fibrotic diseases. Angio- tensin-(1–7) [Ang-(1–7)] is a peptide with actions that oppose those of angiotensin-II (Ang II). Ang-(1–7) effects are mediated by the Mas receptor. Treatment with Ang-(1–7) produce positive effects in the mdx mouse, normalizing skeletal muscle architec- ture, decreasing local fibrosis, and fibroblasts, and improving muscle function. Mdx mice deficient for the Mas receptor showed the opposite effects. To identify the cell type(s) responsi- ble for Mas receptor expression, and to characterize whether profibrotic effectors had any effect on its expression, we deter- mined the effect of profibrotic agents on Mas expression. TGF-b, but not connective tissue growth factor or Ang-II, reduced the expression of Mas receptor in fibroblasts isolated from skeletal muscle cells and fibroblasts from two established cell lines. In contrast, no effects were observed in myoblasts and differenti- ated myotubes. This inhibition was mediated by the Smad- dependent (canonical) and the PI3K and MEK1/2 (noncanonical) TGF-b signaling pathways. When both canonical and noncanoni- cal inhibitors of the TGF-b-dependent pathways were added together, the inhibitory effect of TGF-b on Mas expression was lost. The decrease in Mas receptor induced by TGF-b in fibro- blasts reduced the Ang-(1–7) mediated stimulation of phospho- rylation of AKT pathway proteins. These results suggest that reduction of Mas receptor in fibroblasts, by TGF-b, could increase the fibrotic phenotype observed in dystrophic skeletal muscle decreasing the beneficial effect of Ang-(1–7). V C 2015 Bio- Factors, 00(00):000-000, 2015 Keywords: skeletal muscular dystrophies; Mas receptor; fibrosis; TGF- b; fibroblasts; muscle cells Abbreviations: Ang II, Angiotensin II; Ang-(1–7), angiotensin-(1–7); ACE2, angiotensin-converting enzyme 2; CTGF/CCN2, connective tissue growth fac- tor; DMD, Duchenne muscular dystrophy; ECM, extracellular matrix; mdx, DMD mouse model deficient for dystrophin; TGF-b, Transforming growth fac- tor type b; Wt, wild type. V C 2015 International Union of Biochemistry and Molecular Biology Volume 00, Number 00, Month/Month 2015, Pages 00–00 *Address for correspondence: Enrique Brandan, Ph.D.; Department of Cell and Molecular Biology, Faculty of Biological Sciences, Pontificia Universidad Cat  olica de Chile, Santiago, Chile. Tel.: 156 2 2686 2725; Fax: 156 2 26355395; E-mail: ebrandan@bio.puc.cl. Catalina Cofre and Mar  ıa Jos e Acu~ na contributed equally to this work. Additional Supporting Information may be found in the online version of this article. Received 20 January 2015; accepted 26 February 2015 DOI 10.1002/biof.1208 Published online 00 Month 2015 in Wiley Online Library (wileyonlinelibrary.com) BioFactors 1