title: CCN1/CYR61 overexpression in hepatic stellate cells induces ER stress-related apoptosis.
abstract: CCN1/CYR61 is a matricellular protein of the CCN family, comprising six secreted proteins specifically associated with the extracellular matrix (ECM). CCN1 acts as an enhancer of the cutaneous wound healing process by preventing hypertrophic scar formation through induction of myofibroblast senescence. In liver fibrosis, the senescent cells are primarily derived from activated hepatic stellate cells (HSC) that initially proliferate in response to liver damage and are the major source of ECM. We investigate here the possible use of CCN1 as a senescence inducer to attenuate liver fibrogenesis by means of adenoviral gene transfer in primary HSC, myofibroblasts (MFB) and immortalized HSC lines (i.e. LX-2, CFSC-2G). Infection with Ad5-CMV-CCN1 induced large amounts of CCN1 protein in all these cells, resulting in an overload of the endoplasmic reticulum (ER) and in a compensatory unfolded protein response (UPR). The UPR resulted in upregulation of ER chaperones including BIP/Grp78, Grp94 and led to an activation of IRE1α as evidenced by spliced XBP1 mRNA with IRE1α-induced JNK phosphorylation. The UPR arm PERK and eIF2a was phosphorylated, combined with significant CHOP upregulation. Ad5-CMV-CCN1 induced HSC apoptosis that was evident by proteolytic cleavage of caspase-12, caspase-9 and the executor caspase-3 and positive TUNEL stain. Remarkably, Ad5-CMV-CCN1 effectively reduced collagen type I mRNA expression and protein. We conclude that the matricellular protein CCN1 gene transfer induces HSC apoptosis through ER stress and UPR.
authors.affiliation: Institute of Molecular Pathobiochemistry, Experimental Gene Therapy and Clinical Chemistry, RWTH Aachen University Hospital, Germany. Electronic address: ekamphorst@ukaachen.de.
authors.forename: Erawan
authors.initials: E
authors.lastname: Borkham-Kamphorst
authors.affiliation: Institute of Molecular Pathobiochemistry, Experimental Gene Therapy and Clinical Chemistry, RWTH Aachen University Hospital, Germany.
authors.forename: Bettina T
authors.initials: BT
authors.lastname: Steffen
authors.affiliation: Institute of Molecular Pathobiochemistry, Experimental Gene Therapy and Clinical Chemistry, RWTH Aachen University Hospital, Germany.
authors.forename: Eddy
authors.initials: E
authors.lastname: Van de Leur
authors.affiliation: Institute of Molecular Pathobiochemistry, Experimental Gene Therapy and Clinical Chemistry, RWTH Aachen University Hospital, Germany.
authors.forename: Ute
authors.initials: U
authors.lastname: Haas
authors.affiliation: Institute of Molecular Pathobiochemistry, Experimental Gene Therapy and Clinical Chemistry, RWTH Aachen University Hospital, Germany.
authors.forename: Lidia
authors.initials: L
authors.lastname: Tihaa
authors.affiliation: Division of Liver Diseases, Icahn School of Medicine at Mount Sinai, NY, USA.
authors.forename: Scott L
authors.initials: SL
authors.lastname: Friedman
authors.affiliation: Institute of Molecular Pathobiochemistry, Experimental Gene Therapy and Clinical Chemistry, RWTH Aachen University Hospital, Germany. Electronic address: rweiskirchen@ukaachen.de.
authors.forename: Ralf
authors.initials: R
authors.lastname: Weiskirchen
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D053148:Caspase 3 / Q000378:metabolism; D055515:Cysteine-Rich Protein 61 / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D059865:Endoplasmic Reticulum Stress / Q000502:physiology*; D055166:Hepatic Stellate Cells / Q000378:metabolism*; D008103:Liver Cirrhosis / Q000378:metabolism; D058628:Myofibroblasts / Q000378:metabolism; D017207:Rats, Sprague-Dawley; D056811:Unfolded Protein Response / Q000502:physiology*
chemical_list: C501849:CCN1 protein, rat; D055515:Cysteine-Rich Protein 61; C505410:Casp3 protein, rat; D053148:Caspase 3
keywords: CCN1/CYR61; ER stress; Hepatic stellate cells; Matricellular protein; Myofibroblasts; Unfolded protein response