title: Sphingosine kinase 1 regulates differentiation of human and mouse lung fibroblasts mediated by TGF-beta1.
abstract: Transforming growth factor beta (TGF-beta) contributes to the progression of pulmonary fibrosis through up-regulation of alpha-smooth muscle actin (alpha-SMA) as lung myofibroblast differentiation. Bioactive sphingosine 1-phosphate (S1P) has been shown to mimic TGF-beta signals; however, the function of S1P in lung fibrotic process has not been well documented. We found, in a mouse model of bleomycin lung fibrosis, that SPHK1 and alpha-SMA were colocalized within lung fibrotic foci and that these expressions were significantly increased in primary cultured fibroblasts. Using human lung fibroblasts WI-38, we explored the rationale of sphingosine kinase (SPHK) with TGF-beta1 stimulation. SPHK inhibitors and small interference RNA (siRNA) targeted SPHK1 decreased alpha-SMA and fibronectin expression up-regulated by TGF-beta1. In the meantime, SPHK1 inhibition did not affect smad2 phosphorylation in response to TGF-beta1. Then we examined whether S1P receptors transactivation may affect TGF-beta signals. siRNA against S1P(2) and S1P(3), but not S1P(1), reduced alpha-SMA expression as well as Y-27632, Rho kinase inhibitor. We also detected activation of Rho GTPase upon stimulation of TGF-beta1 on the cell membrane where S1P(2) or S1P(3) was overexpressed. These data suggested that SPHK1 activation by TGF-beta1 leads to Rho-associated myofibroblasts differentiation mediated by transactivated S1P receptors in the lung fibrogenic process.
authors.affiliation: Division of Cardiovascular and Respiratory Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Kobe, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kono
authors.forename: Teruaki
authors.initials: T
authors.lastname: Nishiuma
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Nishimura
authors.forename: Yoshikazu
authors.initials: Y
authors.lastname: Kotani
authors.forename: Taro
authors.initials: T
authors.lastname: Okada
authors.forename: Shun-Ichi
authors.initials: S
authors.lastname: Nakamura
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Yokoyama
mesh_terms: D000818:Animals; D001761:Bleomycin; D002454:Cell Differentiation / Q000187:drug effects*; D002460:Cell Line; D004789:Enzyme Activation / Q000187:drug effects; D005260:Female; D005347:Fibroblasts / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D020868:Gene Silencing; D006801:Humans; D008168:Lung / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D051379:Mice; D008810:Mice, Inbred C57BL; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011658:Pulmonary Fibrosis / Q000139:chemically induced / Q000201:enzymology / Q000473:pathology; D034741:RNA, Small Interfering / Q000378:metabolism; D049349:Receptors, Lysosphingolipid / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D051899:Smad2 Protein / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology*; D015854:Up-Regulation / Q000187:drug effects / Q000235:genetics; D020741:rho GTP-Binding Proteins / Q000378:metabolism; D000099157:Sphingosine Kinase
chemical_list: D001761:Bleomycin; D017853:Phosphotransferases (Alcohol Group Acceptor); D047428:Protein Kinase Inhibitors; D034741:RNA, Small Interfering; D049349:Receptors, Lysosphingolipid; D051899:Smad2 Protein; D053773:Transforming Growth Factor beta1; D020741:rho GTP-Binding Proteins; D000099157:Sphingosine Kinase