title: Serotonin augments smooth muscle differentiation of bone marrow stromal cells.
abstract: Bone marrow stromal cells (BMSCs) contain a subset of multipotent stem cells. Here, we demonstrate that serotonin, a biogenic amine released by platelets and mast cells, can induce the smooth muscle differentiation of BMSCs. Brown Norway rat BMSCs stimulated with serotonin had increased expression of the smooth muscle markers smooth muscle myosin heavy chain (MHC) and α actin (α-SMA) by qPCR and Western blot, indicating smooth muscle differentiation. This was accompanied by a concomitant down-regulation of the microRNA miR-25-5p, which was found to negatively regulate smooth muscle differentiation. Serotonin upregulated serum response factor (SRF) and myocardin, transcription factors known to induce contractile protein expression in smooth muscle cells, while it down-regulated Elk1 and Kruppel-like factor 4 (KLF4), known to induce proliferation. Serotonin increased SRF binding to promoter regions of the MHC and α-SMA genes, assessed by chromatin immunoprecipitation assay. Induction of smooth muscle differentiation by serotonin was blocked by the knock-down of SRF and myocardin. Transforming growth factor (TGF)-β1 was constitutively expressed by BMSCs and serotonin triggered its release. Inhibition of miR-25-5p augmented TGF-β1 expression, however the differentiation of BMSCs was not mediated by TGF-β1. These findings demonstrate that serotonin promotes a smooth muscle-like phenotype in BMSCs by altering the balance of SRF, myocardin, Elk1 and KLF4 and miR-25-5p is involved in modulating this balance. Therefore, serotonin potentially contributes to the pathogenesis of diseases characterized by tissue remodeling with increased smooth muscle mass.
authors.affiliation: Meakins-Christie Laboratories, Department of Medicine, McGill University, 3626 St.-Urbain, Montréal, Québec, H2X 2P2, Canada.
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Hirota
authors.affiliation: Meakins-Christie Laboratories, Department of Medicine, McGill University, 3626 St.-Urbain, Montréal, Québec, H2X 2P2, Canada.
authors.forename: Sarah
authors.initials: S
authors.lastname: McCuaig
authors.affiliation: Meakins-Christie Laboratories, Department of Medicine, McGill University, 3626 St.-Urbain, Montréal, Québec, H2X 2P2, Canada.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: O'Sullivan
authors.affiliation: Meakins-Christie Laboratories, Department of Medicine, McGill University, 3626 St.-Urbain, Montréal, Québec, H2X 2P2, Canada. Electronic address: james.martin@mcgill.ca.
authors.forename: James G
authors.initials: JG
authors.lastname: Martin
mesh_terms: D000818:Animals; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured; D000090062:Kruppel-Like Factor 4; D008297:Male; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D051381:Rats; D012701:Serotonin / Q000235:genetics / Q000378:metabolism*; D026362:Serum Response Factor / Q000235:genetics / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000378:metabolism; D015854:Up-Regulation; D000099251:Myocardin
chemical_list: D000090062:Kruppel-Like Factor 4; D035683:MicroRNAs; D009687:Nuclear Proteins; D012701:Serotonin; D026362:Serum Response Factor; D015534:Trans-Activators; D053773:Transforming Growth Factor beta1; D000099251:Myocardin; C000715469:Klf4 protein, rat