title: Cathepsins L and S are not required for activation of dipeptidyl peptidase I (cathepsin C) in mice.
abstract: The cysteine protease dipeptidyl peptidase I (DPPI) activates granule-associated immune-cell serine proteases. The in vivo activator of DPPI itself is unknown; however, cathepsins L and S are candidates because they activate pro-DPPI in vitro. In this study, we tested whether cathepsins L and S activate pro-DPPI in vivo by characterizing DPPI activity and processing in cells lacking cathepsins L and S. DPPI activity, and the relative size and amounts of DPPI heavy and light chains, were identical in mast cells from wild-type and cathepsin L/S double-null mice. Furthermore, the activity of DPPI-dependent chymase was preserved in tissues of cathepsin L/S double-null mice. These results show that neither cathepsin L nor S is required for activation of DPPI and suggest that one or more additional proteases is responsible.
authors.affiliation: Department of Medicine and Cardiovascular Research Institute, University of California, San Francisco, CA 94143-0111, USA.
authors.forename: Jon
authors.initials: J
authors.lastname: Mallen-St Clair
authors.forename: Guo-Ping
authors.initials: GP
authors.lastname: Shi
authors.forename: Rachel E
authors.initials: RE
authors.lastname: Sutherland
authors.forename: Harold A
authors.initials: HA
authors.lastname: Chapman
authors.forename: George H
authors.initials: GH
authors.lastname: Caughey
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Wolters
mesh_terms: D000818:Animals; D020789:Cathepsin C / Q000378:metabolism*; D056668:Cathepsin L; D002403:Cathepsins / Q000235:genetics / Q000378:metabolism*; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D008407:Mast Cells; D051379:Mice; D018345:Mice, Knockout
chemical_list: D002403:Cathepsins; D020789:Cathepsin C; D003546:Cysteine Endopeptidases; D056668:Cathepsin L; C534278:Ctsl protein, mouse; C028217:cathepsin S