Activin A is an autocrine activator of rat pancreatic stellate cells: potential therapeutic role of follistatin for pancreatic fibrosis.
OBJECTIVE
The present study was conducted to examine the effect of activin A on activation of rat pancreatic stellate cells (PSCs).


METHODS
PSCs were prepared from rat pancreas using collagenase digestion and centrifugation with Nycodenz gradient. Activation of PSCs was examined by determining smooth muscle actin expression with western blotting. The presence of activin A receptors in PSCs was investigated by reverse transcription-polymerase chain reaction (RT-PCR), western blotting, and immunocytochemistry. Expression of activin A and transforming growth factor beta (TGF-beta) mRNA was examined by RT-PCR. Activin A and TGF-beta peptide concentrations were examined with ELISA. Existence of activin A peptide in PSCs was investigated by immunocytochemistry. Collagen secretion was determined by Sirius red dye binding.


RESULTS
Activin A receptors I and IIa were present in PSCs. PSCs expressed activin A mRNA and secreted activin A. Activin A enhanced PSC activation and collagen secretion in a dose dependent manner. TGF-beta and activin A increased each other's secretion and mRNA expression of PSCs. Follistatin decreased TGF-beta mRNA expression and TGF-beta secretion of PSCs, and inhibited both PSC activation and collagen secretion.


CONCLUSIONS
Activin A is an autocrine activator of PSCs. Follistatin can inhibit PSC activation and collagen secretion by blocking autocrined activin A and decreasing TGF-beta expression and secretion of PSCs.
Ohnishi
N
N
Department of Internal Medicine, Jichi Medical School, Tochigi, Japan. hohnishi@jichi.ac.jp
Miyata
T
T
Ohnishi
H
H
Yasuda
H
H
Tamada
K
K
Ueda
N
N
Mashima
H
H
Sugano
K
K
D000199:Actins / Q000032:analysis; D030201:Activin Receptors, Type I / Q000032:analysis / Q000235:genetics; D030301:Activin Receptors, Type II / Q000032:analysis / Q000235:genetics; D028341:Activins / Q000032:analysis / Q000378:metabolism / Q000494:pharmacology*; D000818:Animals; D019898:Autocrine Communication; D015153:Blotting, Western / Q000379:methods; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005355:Fibrosis; D038681:Follistatin / Q000494:pharmacology* / Q000627:therapeutic use; D028322:Inhibin-beta Subunits / Q000032:analysis / Q000378:metabolism / Q000494:pharmacology*; D008856:Microscopy, Fluorescence; D010179:Pancreas / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D011506:Proteins; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016212:Transforming Growth Factor beta / Q000032:analysis / Q000235:genetics / Q000494:pharmacology
D000199:Actins; D038681:Follistatin; D011506:Proteins; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; C422405:activin A; D028341:Activins; D003094:Collagen; D028322:Inhibin-beta Subunits; D030201:Activin Receptors, Type I; D030301:Activin Receptors, Type II; C425585:activin receptor type II-A