Cathepsin K: a cysteine protease with unique kinin-degrading properties.
Taking into account a previous report of an unidentified enzyme from macrophages acting as a kininase, the ability of cysteine proteases to degrade kinins has been investigated. Wild-type fibroblast lysates from mice, by contrast with cathepsin K-deficient lysates, hydrolysed BK (bradykinin), and released two metabolites, BK-(1-4) and BK-(5-9). Cathepsin K, but not cathepsins B, H, L and S, cleaved kinins at the Gly4-Phe5 bond and the bradykinin-mimicking substrate Abz (o-aminobenzoic acid)-RPPGFSPFR-3-NO2-Tyr (3-nitrotyrosine) more efficiently (pH 6.0: kcat/K(m)=12500 mM(-1) x s(-1); pH 7.4: kcat/K(m)=6930 mM(-1) x s(-1)) than angiotensin-converting enzyme hydrolysed BK. Conversely Abz-RPPGFSPFR-3-NO2-Tyr was not cleaved by the Y67L (Tyr67-->Leu)/L205A (Leu205-->Ala) cathepsin K mutant, indicating that kinin degradation mostly depends on the S2 substrate specificity. Kininase activity was further evaluated on bronchial smooth muscles. BK, but not its metabolites BK(1-4) and BK(5-9), induced a dose-dependent contraction, which was abolished by Hoe140, a B2-type receptor antagonist. Cathepsin K impaired BK-dependent contraction of normal and chronic hypoxic rats, whereas cathepsins B and L did not. Taking together vasoactive properties of kinins and the potency of cathepsin K to modulate BK-dependent contraction of smooth muscles, the present data support the notion that cathepsin K may act as a kininase, a unique property among mammalian cysteine proteases.
Godat
Emmanuel
E
INSERM U618, Protéases et Vectorisation Pulmonaires/IFR 135 Imagerie Fonctionnelle, Université François Rabelais, Faculté de Médecine, 2 bis, Boulevard Tonnellé, F-37032 Tours Cédex, France.
Lecaille
Fabien
F
Desmazes
Claire
C
Duchêne
Sophie
S
Weidauer
Enrico
E
Saftig
Paul
P
Brömme
Dieter
D
Vandier
Christophe
C
Lalmanach
Gilles
G
D000818:Animals; D001920:Bradykinin / Q000378:metabolism; D001980:Bronchi / Q000201:enzymology / Q000473:pathology; D056657:Cathepsin K; D002403:Cathepsins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D005347:Fibroblasts / Q000166:cytology / Q000201:enzymology; D005453:Fluorescence; D006801:Humans; D000860:Hypoxia / Q000201:enzymology / Q000473:pathology; D066298:In Vitro Techniques; D007705:Kinins / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018716:Molecular Mimicry / Q000502:physiology; D009130:Muscle, Smooth / Q000201:enzymology; D010455:Peptides / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
D007705:Kinins; D010455:Peptides; D002403:Cathepsins; D003546:Cysteine Endopeptidases; C534130:CTSK protein, human; D056657:Cathepsin K; C534132:Ctsk protein, mouse; C534133:Ctsk protein, rat; D001920:Bradykinin