Increased ADAMTS-13 proteolytic activity in rat hepatic stellate cells upon activation in vitro and in vivo.
BACKGROUND
ADAMTS-13 is a member of A Disintegrin And Metalloprotease with ThromboSpondin type 1 repeats (ADAMTS) family, primarily synthesized in hepatic stellate cells (HSCs), one of the major cell types transdifferentiating into myofibroblasts during liver fibrosis. However, the association between ADAMTS-13 expression and HSC activation or liver fibrosis is not known.


METHODS
In this study, we determined the ADAMTS-13 mRNA, protein, and activity in isolated primary HSCs upon activation on a plastic dish and in liver after administration of carbon tetrachloride (CCl(4)) in rats.


RESULTS
We showed that ADAMTS-13 antigen and proteolytic activity in the activated rat HSCs were dramatically increased, whereas ADAMTS-13 mRNA in these cells was only minimally altered. Similarly, the ADAMTS-13 antigen and proteolytic activity in rat liver after CCl(4) injury were also significantly increased, whereas the ADAMTS-13 mRNAs in these liver tissues were only slightly increased compared with normal. Surprisingly, despite the dramatic up-regulation of ADAMTS-13 protein synthesis in the activated HSCs after CCl(4) administration, the plasma levels of ADAMTS-13 protease in rats did not increase concordantly.


CONCLUSIONS
We conclude that the up-regulation of ADAMTS-13 protein expression in rat HSCs during activation in vitro and in vivo suggests the possibility of ADAMTS-13 proteolysis, an important part of function of the activated HSCs, perhaps through modulation of liver regeneration or formation of liver fibrosis after various injuries. The data also suggest the minimal contribution of the activated HSCs in regulation of plasma levels of ADAMTS-13 protease.
Niiya
M
M
Department of Pathology and Laboratory Medicine, The Children's Hospital of Philadelphia, 34th Street & Civic Center Boulevard, Philadelphia, PA 19104, USA.
Uemura
M
M
Zheng
X W
XW
Pollak
E S
ES
Dockal
M
M
Scheiflinger
F
F
Wells
R G
RG
Zheng
X L
XL
D051722:ADAM Proteins / Q000378:metabolism*; D000071120:ADAMTS13 Protein; D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D006868:Hydrolysis; D007150:Immunohistochemistry; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015854:Up-Regulation
D051722:ADAM Proteins; D000071120:ADAMTS13 Protein; C512067:Adamts13 protein, rat