Molecular insights into connective tissue growth factor action in rat pancreatic stellate cells.
Pancreatic fibrosis, a key feature of chronic pancreatitis and pancreatic cancer, is mediated by activated pancreatic stellate cells (PSC). Connective tissue growth factor (CTGF) has been suggested to play a major role in fibrogenesis by enhancing PSC activation after binding to alpha5beta1 integrin. Here, we have focussed on molecular determinants of CTGF action. Inhibition of CTGF expression in PSC by siRNA was associated with decreased proliferation, while application of exogenous CTGF stimulated both cell growth and collagen synthesis. Real-time PCR studies revealed that CTGF target genes in PSC not only include mediators of matrix remodelling but also the proinflammatory cytokines interleukin (IL)-1beta and IL-6. CTGF stimulated binding of NF-kappaB to the IL-6 promoter, and siRNA targeting the NF-kappaB subunit RelA interfered with CTGF-induced IL-6 expression, implicating the NF-kappaB pathway in the mediation of the CTGF effect. In further studies, we have analyzed regulation of CTGF expression in PSC. Transforming growth factor-beta1, activin A and tumor necrosis factor-alpha enhanced expression of the CTGF gene, while interferon-gamma displayed the opposite effect. The region from -74 to -125 of the CTGF promoter was revealed to be critical for its activity in PSC as well as for the inhibitory effect of interferon-gamma. Taken together, our results indicate a tight control of CTGF expression in PSC at the transcriptional level. CTGF promotes fibrogenesis both directly by enhancing PSC proliferation and matrix protein synthesis, and indirectly through the release of proinflammatory cytokines that may accelerate the process of chronic inflammation.
Karger
Anna
A
Department of Medicine, University of Rostock, E.-Heydemann-Str. 6, 18057 Rostock, Germany.
Fitzner
Brit
B
Brock
Peter
P
Sparmann
Gisela
G
Emmrich
Jörg
J
Liebe
Stefan
S
Jaster
Robert
R
D000818:Animals; D049109:Cell Proliferation; D002478:Cells, Cultured; D003094:Collagen / Q000096:biosynthesis; D055513:Connective Tissue Growth Factor; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D007375:Interleukin-1 / Q000235:genetics / Q000378:metabolism; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D008297:Male; D008954:Models, Biological; D010179:Pancreas / Q000166:cytology* / Q000201:enzymology / Q000254:growth & development / Q000378:metabolism*; D010766:Phosphorylation; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D011917:Rats, Inbred Lew; D050796:STAT3 Transcription Factor / Q000378:metabolism; D015398:Signal Transduction; D051996:Transcription Factor RelA
C526317:CCN2 protein, human; C526316:CCN2 protein, rat; D017874:Immediate-Early Proteins; D036341:Intercellular Signaling Peptides and Proteins; D007375:Interleukin-1; D015850:Interleukin-6; D034741:RNA, Small Interfering; D050796:STAT3 Transcription Factor; D051996:Transcription Factor RelA; D055513:Connective Tissue Growth Factor; D003094:Collagen; D048049:Extracellular Signal-Regulated MAP Kinases