title: Distinct roles of Smad2-, Smad3-, and ERK-dependent pathways in transforming growth factor-beta1 regulation of pancreatic stellate cellular functions.
abstract: Pancreatic stellate cells (PSCs) play a major role in promoting pancreatic fibrosis. Transforming growth factor-beta(1) (TGF-beta(1)) regulates PSC activation and proliferation in an autocrine manner. The intracellular signaling pathways of the regulation were examined in this study. Immunoprecipitation and immunocytochemistry revealed that Smad2, Smad3, and Smad4 were functionally expressed in PSCs. Adenovirus-mediated expression of Smad2, Smad3, or dominant-negative Smad2/3 did not alter TGF-beta(1) mRNA expression level or the amount of autocrine TGF-beta(1) peptide. However, expression of dominant-negative Smad2/3 inhibited PSC activation and enhanced their proliferation. Co-expression of Smad2 with dominant-negative Smad2/3 restored PSC activation inhibited by dominant-negative Smad2/3 expression without changing their proliferation. By contrast, co-expression of Smad3 with dominant-negative Smad2/3 attenuated PSC proliferation enhanced by dominant-negative Smad2/3 expression without altering their activation. Exogenous TGF-beta(1) increased TGFbeta(1) mRNA expression in PSCs. However, PD98059, a specific inhibitor of mitogen-activated protein kinase kinase (MEK1), inhibited ERK activation by TGF-beta(1), and consequently attenuated TGF-beta(1) enhancement of its own mRNA expression in PSCs. We propose that TGF-beta(1) differentially regulates PSC activation, proliferation, and TGF-beta(1) mRNA expression through Smad2-, Smad3-, and ERK-dependent pathways, respectively.
authors.affiliation: Department of Gastroenterology, Jichi Medical School, Tochigi 329-0498, Japan. hohnishi@jichi.ac.jp
authors.forename: Hirohide
authors.initials: H
authors.lastname: Ohnishi
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Miyata
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Yasuda
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Satoh
authors.forename: Kazunobu
authors.initials: K
authors.lastname: Hanatsuka
authors.forename: Hiroto
authors.initials: H
authors.lastname: Kita
authors.forename: Akira
authors.initials: A
authors.lastname: Ohashi
authors.forename: Kiichi
authors.initials: K
authors.lastname: Tamada
authors.forename: Noriko
authors.initials: N
authors.lastname: Makita
authors.forename: Taroh
authors.initials: T
authors.lastname: Iiri
authors.forename: Namiki
authors.initials: N
authors.lastname: Ueda
authors.forename: Hirosato
authors.initials: H
authors.lastname: Mashima
authors.forename: Kentaro
authors.initials: K
authors.lastname: Sugano
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D002478:Cells, Cultured; D003239:Connective Tissue Cells / Q000166:cytology / Q000502:physiology; D004268:DNA-Binding Proteins / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010179:Pancreas / Q000166:cytology / Q000502:physiology*; D051381:Rats; D015398:Signal Transduction; D051899:Smad2 Protein; D051900:Smad3 Protein; D015534:Trans-Activators / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000502:physiology*; D053773:Transforming Growth Factor beta1
chemical_list: D004268:DNA-Binding Proteins; D051899:Smad2 Protein; C497784:Smad2 protein, rat; D051900:Smad3 Protein; C497787:Smad3 protein, rat; C508962:Tgfb1 protein, rat; D015534:Trans-Activators; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D020928:Mitogen-Activated Protein Kinases