title: Sphingosylphosphorylcholine induces differentiation of human mesenchymal stem cells into smooth-muscle-like cells through a TGF-beta-dependent mechanism.
abstract: Mesenchymal stem cells (MSCs) can differentiate into diverse cell types including adipogenic, osteogenic, chondrogenic and myogenic lineages. In the present study, we demonstrated for the first time that sphingosylphosphorylcholine (SPC) induces differentiation of human adipose-tissue-derived mesenchymal stem cells (hATSCs) to smooth-muscle-like cell types. SPC increased the expression levels of several smooth-muscle-specific genes, such as those for alpha-smooth-muscle actin (alpha-SMA), h1-calponin and SM22alpha, as effectively as transforming growth factor beta (TGF-beta1) and TGF-beta3. SPC elicited delayed phosphorylation of Smad2 after 24 hours exposure, in contrast to rapid phosphorylation of Smad2 induced by TGF-beta treatment for 10 minutes. Pretreatment of the cells with pertussis toxin or U0126, an MEK inhibitor, markedly attenuated the SPC-induced expression of beta-SMA and delayed phosphorylation of Smad2, suggesting that the Gi/o-ERK pathway is involved in the increased expression of alpha-SMA through induction of delayed Smad2 activation. In addition, SPC increased secretion of TGF-beta1 through an ERK-dependent pathway, and the SPC-induced expression of alpha-SMA and delayed phosphorylation of Smad2 were blocked by SB-431542, a TGF-beta type I receptor kinase inhibitor, or anti-TGF-beta1 neutralizing antibody. Silencing of Smad2 expression with small interfering RNA (siRNA) abrogated the SPC-induced expression of alpha-SMA. These results suggest that SPC-stimulated secretion of TGF-beta1 plays a crucial role in SPC-induced smooth muscle cell (SMC) differentiation through a Smad2-dependent pathway. Both SPC and TGF-beta increased the expression levels of serum-response factor (SRF) and myocardin, transcription factors involved in smooth muscle differentiation. siRNA-mediated depletion of SRF or myocardin abolished the alpha-SMA expression induced by SPC or TGF-beta. These results suggest that SPC induces differentiation of hATSCs to smooth-muscle-like cell types through G(i/o)-ERK-dependent autocrine secretion of TGF-beta, which activates a Smad2-SRF/myocardin-dependent pathway.
authors.affiliation: Medical Research Center for Ischemic Tissue Regeneration of Pusan National University and the Medical Research Institute, College of Medicine, Pusan National University, Busan 602-739, Republic of Korea.
authors.forename: Eun Su
authors.initials: ES
authors.lastname: Jeon
authors.forename: Hyun Jung
authors.initials: HJ
authors.lastname: Moon
authors.forename: Mi Jeong
authors.initials: MJ
authors.lastname: Lee
authors.forename: Hae Young
authors.initials: HY
authors.lastname: Song
authors.forename: Young Mi
authors.initials: YM
authors.lastname: Kim
authors.forename: Yong Chan
authors.initials: YC
authors.lastname: Bae
authors.forename: Jin Sup
authors.initials: JS
authors.lastname: Jung
authors.forename: Jae Ho
authors.initials: JH
authors.lastname: Kim
mesh_terms: D000199:Actins / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000502:physiology; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000187:drug effects; D009130:Muscle, Smooth / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D009687:Nuclear Proteins / Q000502:physiology; D010766:Phosphorylation / Q000187:drug effects; D010767:Phosphorylcholine / Q000031:analogs & derivatives* / Q000494:pharmacology; D026362:Serum Response Factor / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects; D051899:Smad2 Protein / Q000378:metabolism; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D022502:Stress Fibers / Q000187:drug effects / Q000378:metabolism; D050151:Subcutaneous Fat / Q000166:cytology; D015534:Trans-Activators / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000502:physiology*; D053773:Transforming Growth Factor beta1 / Q000378:metabolism; D000099251:Myocardin
chemical_list: D000199:Actins; D048049:Extracellular Signal-Regulated MAP Kinases; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D009687:Nuclear Proteins; D010767:Phosphorylcholine; D026362:Serum Response Factor; D051899:Smad2 Protein; D013110:Sphingosine; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D000099251:Myocardin; C497782:SMAD2 protein, human; C476858:SRF protein, human; C005356:sphingosine phosphorylcholine