Hepatocyte growth factor regulates proteoglycan synthesis in interstitial fibroblasts.
BACKGROUND
Hepatocyte growth factor (HGF) is a clinically important growth factor with therapeutic potential for the treatment of interstitial fibrosis and chronic renal failure. Proteoglycans are components of the renal interstitium, which have multiple actions, including growth regulation. In this study, we examined the effects of HGF on proteoglycan synthesis in interstitial fibroblasts, and the mechanisms of these effects.


RESULTS
Expression and agonist-induced activation of the HGF receptor c-Met was detected in rat renal interstitial fibroblasts (NRK-49F) by reverse transcription-polymerase chain reaction (RT-PCR) analysis and immune complex/immunoblot assay. Moreover, stimulation of the cells with HGF resulted in a marked increase (five- to tenfold) in phosphorylation of extracellular signal-related protein kinase (ERK) 1/2 and p38 mitogen-activated protein kinase (MAPK), but not of c-Jun NH2 terminal kinase (JNK). Treatment with HGF resulted in a time- and dose-dependent increase (P < 0.01) in both cell-associated and secreted proteoglycan synthesis to two- to fourfold of control levels. This effect was attenuated by the MAPK/ERK kinase (MEK) inhibitor PD98059 and the p38 MAPK inhibitor SB203580. Ion-exchange chromatography suggested that chondroitin sulfate/dermatan sulfate proteoglycans were up-regulated after HGF treatment. Northern blot, RT-PCR, Western blot, and promoter activity assays revealed that HGF caused a significant increase in decorin mRNA and protein, as well as in biglycan mRNA, protein, and promoter activity, suggesting transcriptional control of gene expression. Since the effects of biglycan on fibroblast proliferation are still unclear, the effects of biglycan were examined by thymidine assay, and biglycan was found to attenuate transforming growth factor-beta (TGF-beta)-induced changes in cell proliferation.


CONCLUSIONS
These results suggest that HGF causes an increase in the small leucine-rich proteoglycans biglycan and decorin by ERK1/2- and p38 MAPK-mediated pathways in fibroblasts. These findings may be relevant for understanding potential mechanisms by which HGF can exert TGF-beta inhibitory actions in the kidney.
Kobayashi
Emi
E
Department of Internal Medicine, School of Medicine, Keio University, Tokyo, Japan.
Sasamura
Hiroyuki
H
Mifune
Mizuo
M
Shimizu-Hirota
Ryoko
R
Kuroda
Mari
M
Hayashi
Matsuhiko
M
Saruta
Takao
T
D053674:Aggrecans; D000818:Animals; D058578:Biglycan; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016326:Extracellular Matrix Proteins; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D006023:Glycoproteins / Q000378:metabolism; D017228:Hepatocyte Growth Factor / Q000494:pharmacology / Q000502:physiology*; D048031:JNK Mitogen-Activated Protein Kinases; D007668:Kidney / Q000166:cytology / Q000378:metabolism*; D037181:Lectins, C-Type; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011509:Proteoglycans / Q000096:biosynthesis* / Q000494:pharmacology; D019859:Proto-Oncogene Proteins c-met / Q000378:metabolism / Q000502:physiology; D051381:Rats; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases
C508321:Acan protein, rat; D053674:Aggrecans; C546886:Bgn protein, rat; D058578:Biglycan; D004791:Enzyme Inhibitors; D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; D037181:Lectins, C-Type; D011509:Proteoglycans; D016212:Transforming Growth Factor beta; D017228:Hepatocyte Growth Factor; D019859:Proto-Oncogene Proteins c-met; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases