Distinct roles of Smad2-, Smad3-, and ERK-dependent pathways in transforming growth factor-beta1 regulation of pancreatic stellate cellular functions.
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.
Ohnishi
Hirohide
H
Department of Gastroenterology, Jichi Medical School, Tochigi 329-0498, Japan. hohnishi@jichi.ac.jp
Miyata
Tomohiko
T
Yasuda
Hiroshi
H
Satoh
Yukihiro
Y
Hanatsuka
Kazunobu
K
Kita
Hiroto
H
Ohashi
Akira
A
Tamada
Kiichi
K
Makita
Noriko
N
Iiri
Taroh
T
Ueda
Namiki
N
Mashima
Hirosato
H
Sugano
Kentaro
K
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
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