Cathepsins L and S are not required for activation of dipeptidyl peptidase I (cathepsin C) in mice.
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.
Mallen-St Clair
Jon
J
Department of Medicine and Cardiovascular Research Institute, University of California, San Francisco, CA 94143-0111, USA.
Shi
Guo-Ping
GP
Sutherland
Rachel E
RE
Chapman
Harold A
HA
Caughey
George H
GH
Wolters
Paul J
PJ
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
D002403:Cathepsins; D020789:Cathepsin C; D003546:Cysteine Endopeptidases; D056668:Cathepsin L; C534278:Ctsl protein, mouse; C028217:cathepsin S