Connective tissue growth factor induces c-fos gene activation and cell proliferation through p44/42 MAP kinase in primary rat hepatic stellate cells.
OBJECTIVE
Connective tissue growth factor (CCN2) is expressed during activation of hepatic stellate cells (HSC) and promotes HSC proliferation, adhesion, and collagen production. The aim of the study was to investigate CCN2 signaling pathways in HSC.


METHODS
Primary HSC were obtained by enzymatic perfusion of rat liver. DNA synthesis was evaluated by [(3)H]thymidine incorporation. Phosphorylation of Elk-1, extracellular signal-regulated kinase (ERK1/2) and focal adhesion kinase (FAK) was evaluated by Western blot. Transcriptional factor binding activity was determined by gel mobility shift assay while c-fos promoter and CCN2 promoter activity was evaluated using luciferase reporters. c-fos mRNA expression was evaluated by Northern blot.


RESULTS
CCN2 stimulated DNA synthesis and phosphorylation of FAK, Elk-1 and ERK1/2, the latter of which was blocked by heparin. The serum response element binding activity and luciferase reporter activity of the c-fos promoter, together with expression of c-fos, were enhanced by CCN2. CCN2-induced c-fos gene activation, expression and cell proliferation were blocked by inhibiting ERK1/2 with PD98059. CCN2 promoter activity was enhanced by TGF-beta1 or PDGF via a Smad7-dependent pathway.


CONCLUSIONS
CCN2-stimulated HSC DNA synthesis is associated with transient induction of c-fos gene activation and expression as well as activation of the ERK1/2 signal pathway.
Gao
Runping
R
Laboratoire d'Oncologie Virale et Moléculaire, Université Paris 7, Diderot 75005, France.
Ball
DeAnna K
DK
Perbal
Bernard
B
Brigstock
David R
DR
D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D055513:Connective Tissue Growth Factor; D004268:DNA-Binding Proteins / Q000378:metabolism; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; D015870:Gene Expression / Q000502:physiology; D005786:Gene Expression Regulation / Q000187:drug effects*; D016762:Genes, fos; D022781:Hepatocytes / Q000201:enzymology / Q000502:physiology*; D017874:Immediate-Early Proteins / Q000494:pharmacology*; D036341:Intercellular Signaling Peptides and Proteins / Q000494:pharmacology*; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000494:pharmacology; D027602:Serum Response Element / Q000502:physiology; D026362:Serum Response Factor / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D053773:Transforming Growth Factor beta1; D050807:ets-Domain Protein Elk-1
C526316:CCN2 protein, rat; D004268:DNA-Binding Proteins; C494114:Elk1 protein, rat; D017874:Immediate-Early Proteins; D036341:Intercellular Signaling Peptides and Proteins; D010982:Platelet-Derived Growth Factor; D011518:Proto-Oncogene Proteins; D011994:Recombinant Proteins; D026362:Serum Response Factor; C508962:Tgfb1 protein, rat; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1; D050807:ets-Domain Protein Elk-1; D055513:Connective Tissue Growth Factor; D011505:Protein-Tyrosine Kinases; D051417:Focal Adhesion Kinase 1; D051416:Focal Adhesion Protein-Tyrosine Kinases; C496052:Ptk2 protein, rat; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases