The anti-fibrotic effects of CCN1/CYR61 in primary portal myofibroblasts are mediated through induction of reactive oxygen species resulting in cellular senescence, apoptosis and attenuated TGF-β signaling.
Cysteine-rich protein 61 (CCN1/CYR61) is a CCN (CYR61, CTGF (connective tissue growth factor), and NOV (Nephroblastoma overexpressed gene)) family matricellular protein comprising six secreted CCN proteins in mammals. CCN1/CYR61 expression is associated with inflammation and injury repair. Recent studies show that CCN1/CYR61 limits fibrosis in models of cutaneous wound healing by inducing cellular senescence in myofibroblasts of the granulation tissue which thereby transforms into an extracellular matrix-degrading phenotype. We here investigate CCN1/CYR61 expression in primary profibrogenic liver cells (i.e., hepatic stellate cells and periportal myofibroblasts) and found an increase of CCN1/CYR61 expression during early activation of hepatic stellate cells that declines in fully transdifferentiated myofibroblasts. By contrast, CCN1/CYR61 levels found in primary parenchymal liver cells (i.e., hepatocytes) were relatively low compared to the levels exhibited in hepatic stellate cells and portal myofibroblasts. In models of ongoing liver fibrogenesis, elevated levels of CCN1/CYR61 were particularly noticed during early periods of insult, while expression declined during prolonged phases of fibrogenesis. We generated an adenovirus type 5 encoding CCN1/CYR61 (i.e., Ad5-CMV-CCN1/CYR61) and overexpressed CCN1/CYR61 in primary portal myofibroblasts. Interestingly, overexpressed CCN1/CYR61 significantly inhibited production of collagen type I at both mRNA and protein levels as evidenced by quantitative real-time polymerase chain reaction, Western blot and immunocytochemistry. CCN1/CYR61 further induces production of reactive oxygen species (ROS) leading to dose-dependent cellular senescence and apoptosis. Additionally, we demonstrate that CCN1/CYR61 attenuates TGF-β signaling by scavenging TGF-β thereby mitigating in vivo liver fibrogenesis in a bile duct ligation model.


CONCLUSIONS
In line with dermal fibrosis and scar formation, CCN1/CYR61 is involved in liver injury repair and tissue remodeling. CCN1/CYR61 gene transfer into extracellular matrix-producing liver cells is therefore potentially beneficial in liver fibrotic therapy.
Institute of Clinical Chemistry and Pathobiochemistry, RWTH Aachen University Hospital, Germany. Electronic address: ekamphorst@ukaachen.de.
Erawan
E
Borkham-Kamphorst
Institute of Clinical Chemistry and Pathobiochemistry, RWTH Aachen University Hospital, Germany.
Christian
C
Schaffrath
Institute of Clinical Chemistry and Pathobiochemistry, RWTH Aachen University Hospital, Germany.
Eddy
E
Van de Leur
Institute of Clinical Chemistry and Pathobiochemistry, RWTH Aachen University Hospital, Germany.
Ute
U
Haas
Institute of Clinical Chemistry and Pathobiochemistry, RWTH Aachen University Hospital, Germany.
Lidia
L
Tihaa
Institute of Clinical Chemistry and Pathobiochemistry, RWTH Aachen University Hospital, Germany.
Steffen K
SK
Meurer
Department of Internal Medicine III, RWTH Aachen University Hospital, Germany.
Yulia A
YA
Nevzorova
Department of Internal Medicine III, RWTH Aachen University Hospital, Germany.
Christian
C
Liedtke
Institute of Clinical Chemistry and Pathobiochemistry, RWTH Aachen University Hospital, Germany. Electronic address: rweiskirchen@ukaachen.de.
Ralf
R
Weiskirchen
D000818:Animals; D017209:Apoptosis; D016922:Cellular Senescence; D055515:Cysteine-Rich Protein 61 / Q000502:physiology*; D008297:Male; D058628:Myofibroblasts / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction; D016212:Transforming Growth Factor beta / Q000378:metabolism*
C501849:CCN1 protein, rat; D055515:Cysteine-Rich Protein 61; D017382:Reactive Oxygen Species; D016212:Transforming Growth Factor beta
Apoptosis; CCN protein; Hepatic stellate cell; Myofibroblast; Portal myofibroblast; Senescence