title: Nuclear cathepsin F regulates activation markers in rat hepatic stellate cells.
abstract: Activation of hepatic stellate cells during liver fibrosis is a major event facilitating an increase in extracellular matrix deposition. The up-regulation of smooth muscle alpha-actin and collagen type I is indicative of the activation process. The involvement of cysteine cathepsins, a class of lysosomal cysteine proteases, has not been studied in conjunction with the activation process of hepatic stellate cells. Here we report a nuclear cysteine protease activity partially attributed to cathepsin F, which co-localizes with nuclear speckles. This activity can be regulated by treatment with retinol/palmitic acid, known to reduce the hepatic stellate cell activation. The treatment for 48 h leads to a decrease in activity, which is coupled to an increase in cystatin B and C transcripts. Cystatin B knockdown experiments during the same treatment confirm the regulation of the nuclear activity by cystatin B. We demonstrate further that the inhibition of the nuclear activity by E-64d, a cysteine protease inhibitor, results in a differential regulation of smooth muscle alpha-actin and collagen type I transcripts. On the other hand, cathepsin F small interfering RNA transfection leads to a decrease in nuclear activity and a transcriptional down-regulation of both activation markers. These findings indicate a possible link between nuclear cathepsin F activity and the transcriptional regulation of hepatic stellate cell activation markers.
authors.affiliation: Department of Tissue Engineering, Institute of Bioengineering and Nanotechnology, Singapore 138669. gmaubach@ibn.a-star.edu.sg
authors.forename: Gunter
authors.initials: G
authors.lastname: Maubach
authors.forename: Michelle Chin Chia
authors.initials: MC
authors.lastname: Lim
authors.forename: Lang
authors.initials: L
authors.lastname: Zhuo
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D056646:Cathepsin F; D002403:Cathepsins / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D005786:Gene Expression Regulation; D022781:Hepatocytes / Q000378:metabolism*; D008954:Models, Biological; D008969:Molecular Sequence Data; D034741:RNA, Small Interfering / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D034741:RNA, Small Interfering; D002403:Cathepsins; D056646:Cathepsin F; C534093:Ctsf protein, rat