An activity-based probe for the determination of cysteine cathepsin protease activities in whole cells.
We describe a novel diazomethylketone-containing irreversible inhibitor (BIL-DMK) which is specific for a subset of pharmaceutically important cysteine cathepsin proteases. BIL-DMK rapidly inactivates cathepsins B, F, K, L, S, and V in isolated enzyme assays and labels cathepsins in whole cells. The presence of catalytically active cathepsins B, L, and K or S was demonstrated using radioiodinated BIL-DMK in HepG2 (hepatoma), HIG82 (rabbit synoviocyte), and Ramos (B lymphoma) cell lines, respectively. The identity of each protein labeled was confirmed from the isoelectric point and molecular mass of the radioactive spots on two-dimensional gel and by comigration with each cathepsin as identified by immunoblotting. These cell lines were used to establish whole-cell enzyme occupancy assays to determine the potency of both irreversible and reversible inhibitors against each cathepsin in their native cellular lysosomal or endosomal environment. These whole-cell enzyme occupancy assays are useful to determine the cellular permeability of competing inhibitors and have the advantage of not requiring specific substrates for each cathepsin of interest.
Falgueyret
Jean-Pierre
JP
Department of Biochemistry and Molecular Biology, Merck Frosst Centre for Therapeutic Research, Kirkland, Que., Canada.
Black
W Cameron
WC
Cromlish
Wanda
W
Desmarais
Sylvie
S
Lamontagne
Sonia
S
Mellon
Christophe
C
Riendeau
Denis
D
Rodan
Sevgi
S
Tawa
Paul
P
Wesolowski
Gregg
G
Bass
Kathryn E
KE
Venkatraman
Shankar
S
Percival
M David
MD
D000818:Animals; D001345:Autoradiography; D001713:Biphenyl Compounds / Q000494:pharmacology*; D015153:Blotting, Western; D002401:Cathepsin B / Q000032:analysis / Q000037:antagonists & inhibitors; D056657:Cathepsin K; D056668:Cathepsin L; D002403:Cathepsins / Q000032:analysis / Q000037:antagonists & inhibitors / Q000378:metabolism*; D045744:Cell Line, Tumor; D003546:Cysteine Endopeptidases / Q000032:analysis; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology*; D003978:Diazomethane / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000494:pharmacology; D006801:Humans; D007457:Iodine Radioisotopes; D007930:Leucine / Q000031:analogs & derivatives* / Q000494:pharmacology; D011817:Rabbits
D001713:Biphenyl Compounds; D015853:Cysteine Proteinase Inhibitors; D007457:Iodine Radioisotopes; C503724:N-((1S)-1-(((1-(2-diazoacetyl)butyl)amino)carbonyl)-3-methylbutyl)-4'-iodo-(1,1'-biphenyl)-4-carboxamide; C015795:diazomethyl ketones; D003978:Diazomethane; D002403:Cathepsins; D003546:Cysteine Endopeptidases; D002401:Cathepsin B; C534281:CTSL protein, human; D056668:Cathepsin L; C028217:cathepsin S; C534130:CTSK protein, human; D056657:Cathepsin K; D007930:Leucine