Transforming growth factor-beta induces contraction of activated hepatic stellate cells.
OBJECTIVE
Transforming growth factor-beta (TGF-beta) is a cytokine produced in abundance during liver injury. Recognizing the prominent roles that hepatic stellate cells (HSCs) and TGF-beta play in portal hypertension and fibrogenesis, respectively, we sought to evaluate the effect of TGF-beta on the contractility of activated HSCs.


METHODS
Spontaneous immortalized cell lines of HSC origin were used in this study. Cells were grown in three-dimensional collagen gel lattice, transferred to 60 mm dishes and exposed to varying concentrations of TGF-beta1 in serum-free medium at 37 degrees C for up to 120 h. The area of the floating gels was measured using a Fluor S-MultiImager (Biorad), the cellular smooth muscle-alpha actin (SMA) content quantified and PKC activation studies conducted.


RESULTS
TGF-beta1 induced a time- and dose-dependent decrease in lattice area up to 40% of control (P<0.05) that reflects the contraction of activated HSCs. This induced contraction was associated with increases in SMA content (3-fold, P<0.05) and PKC activation (5-fold, P<0.05) in these cells. Furthermore, pre-incubating with a PKC--specific inhibitor completely abrogated the TGF-beta-induced contraction.


CONCLUSIONS
TGF-beta induces contraction of activated HSCs via an increase in SMA content and a PKC--mediated pathway.
Kharbanda
Kusum K
KK
Department of Veterans Affairs Medical Center, VA Alcohol Research Center, 4101 Woolworth Avenue, Omaha, NE 68105, USA. kkharbanda@unmc.edu
Rogers
David D
DD
Wyatt
Todd A
TA
Sorrell
Michael F
MF
Tuma
Dean J
DJ
D000199:Actins / Q000378:metabolism; D000818:Animals; D002461:Cell Line, Transformed; D003094:Collagen / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D006975:Hypertension, Portal / Q000378:metabolism*; D008297:Male; D011493:Protein Kinase C / Q000378:metabolism; D051744:Protein Kinase C-epsilon; D051381:Rats; D017208:Rats, Wistar; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
D000199:Actins; D016212:Transforming Growth Factor beta; D003094:Collagen; C497257:Prkce protein, rat; D011493:Protein Kinase C; D051744:Protein Kinase C-epsilon