title: Diverse signaling pathways regulate fibroblast differentiation and transformation through Rho kinase activation.
abstract: This study examined the role of agonist-induced Rho kinase (ROCK) involvement in the morphological outcome of pulmonary-derived fibroblasts. Normal human lung fibroblasts (NHLF) spontaneously differentiate into network-like structures in a two-dimensional growth factor reduced Matrigel matrix-based assay. Sphingosine 1-phosphate (SPP), a bioactive phospholipid that regulates angiogenesis, inhibited fibroblast morphogenesis in a dose-dependent manner, virtually eliminating the presence of multi-cellular structures at 500 nM. Pretreatment with the Rho kinase-specific inhibitor, H1152, eradicated the high dose SPP-induced inhibition. Similarly, NHLFs transfected with Rho kinase siRNA prevented SPP-induced inhibition of the fibroblast morphogenesis. Alternatively, transforming growth factor-beta1 (TGF-beta1), a cytokine recognized as a key mediator of wound healing, terminally differentiates NHLF into myofibroblasts as evidenced by the expression of the smooth muscle cell isoform of alpha-actin (alpha-SMA). H1152 suppressed TGF-beta1-induced alpha-SMA expression in a dose-dependent manner. Similarly, treatment with Rho kinase siRNA reduced alpha-SMA expression by greater than 50%. SPP treatment had no effect on TGF-beta1-induced transformation into myofibroblasts, and TGF-beta1 treatment did not alter fibroblast morphogenesis. This study suggests a dual regulatory role for Rho kinase in cellular regulation of fibroblasts in which SPP-induced Rho kinase activation via a G-protein coupled receptor suppresses fibroblast morphogenesis while TGF-beta1-induced Rho kinase activation through a serine/threonine kinase receptor culminates in transformation into myofibroblasts.
authors.affiliation: Cellular Biochemistry Laboratory, Methodist Research Institute, Clarian Health Partners, Indianapolis, Indiana, USA.
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Harvey
authors.forename: Corine Nivanka
authors.initials: CN
authors.lastname: Paranavitana
authors.forename: Gary P
authors.initials: GP
authors.lastname: Zaloga
authors.forename: Rafat A
authors.initials: RA
authors.lastname: Siddiqui
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000031:analogs & derivatives / Q000494:pharmacology; D000199:Actins / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D019070:Cell Lineage; D048430:Cell Shape; D003094:Collagen / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D004789:Enzyme Activation; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D007797:Laminin / Q000378:metabolism; D008168:Lung / Q000166:cytology / Q000378:metabolism; D008246:Lysophospholipids / Q000494:pharmacology; D009024:Morphogenesis / Q000187:drug effects; D010641:Phenotype; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011509:Proteoglycans / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013110:Sphingosine / Q000031:analogs & derivatives / Q000494:pharmacology; D013997:Time Factors; D014162:Transfection; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology; D054460:rho-Associated Kinases
chemical_list: C459092:2-methyl-1-((4-methyl-5-isoquinolinyl)sulfonyl)homopiperazine; D000199:Actins; D004338:Drug Combinations; D047908:Intracellular Signaling Peptides and Proteins; D007797:Laminin; D008246:Lysophospholipids; D047428:Protein Kinase Inhibitors; D011509:Proteoglycans; D034741:RNA, Small Interfering; D053773:Transforming Growth Factor beta1; C059485:matrigel; C060506:sphingosine 1-phosphate; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D003094:Collagen; D017346:Protein Serine-Threonine Kinases; D054460:rho-Associated Kinases; D013110:Sphingosine