Journal Article

Cultured rat glomerular epithelial cells show gene expression and production of transforming growth factor‐β: expression is enhanced by thrombin

Satoru Tsunoda, Hideaki Yamabe, Hiroshi Osawa, Mitsuaki Kaizuka, Kenichi Shirato and Ken Okumura

in Nephrology Dialysis Transplantation

Published on behalf of European Renal Association - European Dialysis and Transplant Assoc

Volume 16, issue 9, pages 1776-1782
Published in print September 2001 | ISSN: 0931-0509
Published online September 2001 | e-ISSN: 1460-2385 | DOI: http://dx.doi.org/10.1093/ndt/16.9.1776
Cultured rat glomerular epithelial cells show gene expression and production of transforming growth factor‐β: expression is enhanced by thrombin

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Background. Glomerular crescents play an important role in progressive glomerular injury. The lesions consist of epithelial cells, macrophages, and deposits of fibrin and extracellular matrix. Transforming growth factor beta (TGF‐β) contributes to the modulation of cell growth and extracellular matrix synthesis. Thrombin is involved in fibrin formation in crescents. The purpose of this study was to examine whether glomerular epithelial cells (GEC) could produce TGF‐β, and if so, to clarify the role of TGF‐β in GEC proliferation. We also investigated whether thrombin could modulate the production of TGF‐β and extracellular matrix by GEC.

Methods. Bioassay using the TGF‐β‐dependent mink pulmonary epithelial cell line (CCL‐64), immunoblot analysis, and reverse transcriptase polymerase chain reaction (RT‐PCR) were used to demonstrate TGF‐β production by rat GEC. TGF‐β gene expression was examined by RT‐PCR in GEC incubated with thrombin, and type IV collagen and fibronectin were quantified by enzyme immunoassay in culture supernatants of GEC incubated with thrombin or TGF‐β.

Results. TGF‐β activity was demonstrated in GEC supernatants by bioassay. Immunoblot analysis of concentrated culture supernatants using anti‐TGF‐β antibody revealed a 12.5‐kDa protein, which was compatible with TGF‐β. Concentrated GEC supernatants inhibited GEC proliferation as well as porcine TGF‐β. RT‐PCR demonstrated TGF‐β gene expression in GEC. Thrombin (0.5–5.0 U/ml) enhanced TGF‐β mRNA expression in a dose‐dependent manner. Thrombin (5.0 U/ml) and porcine TGF‐β (5.0 ng/ml) stimulated the production of type IV collagen and fibronectin by GEC.

Conclusions. Rat GEC produce TGF‐β in vitro. Thrombin may participate in the progression of glomerulosclerosis in crescentic glomerulonephritis through the stimulation of TGF‐β production by GEC.

Keywords: fibronectin; glomerular epithelial cells; rat; TGF‐β; thrombin; type IV collagen

Journal Article.  3881 words.  Illustrated.

Subjects: Nephrology

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