Tropoelastin expression is up-regulated during activation of hepatic stellate cells and in the livers of CCl(4)-cirrhotic rats.
OBJECTIVE
Activated hepatic stellate cells (HSC) are regarded as the principal cells synthesizing extracellular matrix components in fibrotic liver. Elastin content is increased in cirrhotic livers, but the cellular source is not known. Contribution of HSC to the production of elastin was investigated.


METHODS
Expression of elastin in CCl(4)-cirrhotic rat liver was studied by immunohistochemistry and in situ hybridization, liver myofibroblasts were identified in histological sections by alpha-smooth muscle actin (alpha-SMA) staining. LightCycler PCR and Northern blotting were used to detect tropoelastin mRNA in isolated HSC; tropoelastin protein was detected in the cells and in cell-conditioned medium by Western blotting.


RESULTS
HSC, isolated from normal rat liver, displayed increasing tropoelastin mRNA expression during transdifferentiation in culture. Expression of tropoelastin mRNA was accompanied by the production of tropoelastin protein in vitro. Increased levels of tropoelastin transcripts were found in the connective tissue septa of CCl(4)-cirrhotic rats and co-localized with alpha-SMA positive cells. Immunohistochemistry demonstrated elastin presence in the septa.


CONCLUSIONS
HSC express tropoelastin and its expression increases during transdifferentiation to myofibroblast-like cells.
Kanta
Jiri
J
Department of Medical Biochemistry, Medical Faculty in Hradec Kralove, Charles University in Prague, Czech Republic. kanta@lfhk.cuni.cz
Dooley
Steven
S
Delvoux
Bert
B
Breuer
Sebastian
S
D'Amico
Thomas
T
Gressner
Axel M
AM
D000199:Actins / Q000378:metabolism; D000818:Animals; D002251:Carbon Tetrachloride / Q000633:toxicity; D002478:Cells, Cultured; D004195:Disease Models, Animal; D004587:Electrophoresis, Agar Gel; D019084:Fluorescent Antibody Technique, Indirect; D017403:In Situ Hybridization; D007728:Kupffer Cells / Q000378:metabolism* / Q000473:pathology; D008099:Liver / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D008106:Liver Cirrhosis, Experimental / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014333:Tropoelastin / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation
D000199:Actins; D012333:RNA, Messenger; D014333:Tropoelastin; D002251:Carbon Tetrachloride