Inhibition of normal rat kidney cell growth by transforming growth factor-beta is mediated by collagen.
We have investigated the mechanism of inhibition of the serum-free monolayer growth of normal rat kidney (NRK) cells by transforming growth factor-beta (TGF-beta). NRK cells grown on fibronectin-coated dishes exhibited a biphasic response to TGF-beta. Monolayer growth was slightly stimulated by subpicomolar concentrations, while picomolar concentrations of TGF-beta inhibited NRK cell growth in the presence or absence of epidermal growth factor. NRK cells exhibited a similar biphasic growth response to exogenous type I collagen. TGF-beta induced a 3-5-fold increase in the deposition of type I collagen-like proteins into the extracellular matrix of NRK cells during serum-free growth. Type I collagen-like proteins were identified by their sensitivity to degradation by purified bacterial collagenase and by Western blot analysis. The TGF-beta dose-response curves for induction of extracellular matrix-localized collagen and inhibition of NRK cell growth were similar. Finally, the inclusion of a purified bacterial collagenase, which did not degrade TGF-beta or TGF-beta receptors, or alter control NRK growth, prevented exogenous collagen or TGF-beta from inhibiting the serum-free growth of NRK cells. Our results demonstrate that an increase in collagen secretion plays an important role in the inhibition of the growth of NRK cells by TGF-beta.
Nugent
M A
MA
Roche Institute of Molecular Biology, Roche Research Center, Nutley, New Jersey 07110.
Newman
M J
MJ
D000818:Animals; D002455:Cell Division / Q000187:drug effects*; D002460:Cell Line; D003094:Collagen / Q000494:pharmacology*; D003470:Culture Media; D005109:Extracellular Matrix / Q000378:metabolism; D015151:Immunoblotting; D007668:Kidney; D007700:Kinetics; D003012:Microbial Collagenase / Q000378:metabolism; D014176:Protein Biosynthesis; D011506:Proteins / Q000302:isolation & purification; D051381:Rats; D015291:Transforming Growth Factors / Q000494:pharmacology*
D003470:Culture Media; D011506:Proteins; D015291:Transforming Growth Factors; D003094:Collagen; D003012:Microbial Collagenase