title: A multifunctional protease inhibitor to regulate endolysosomal function.
abstract: Proteases constitute a major class of drug targets. Endosomal compartments harbor several protease families whose attenuation may be beneficial to a number of biological processes, including inflammation, cancer metastasis, antigen presentation, and parasite clearance. As a step toward the goal of generalized but targeted protease inhibition in the endocytic pathway, we describe here the synthesis, characterization, and cellular application of a novel multifunctional protease inhibitor. We show that pepstatin A, a potent but virtually insoluble inhibitor of cathepsins D and E, can be conjugated to a single site on cystatin C, a potent inhibitor of the papain-like cysteine proteases (PLCP) and of asparagine endopeptidease (AEP), to create a highly soluble compound capable of suppressing the activity of all 3 principal protease families found in endosomes and lysosomes. We demonstrate that this cystatin-pepstatin inhibitor (CPI) can be taken up by cells to modulate protease activity and affect biological responses.
authors.affiliation: Division of Cell Signalling and Immunology, College of Life Sciences, University of Dundee, U.K.
authors.forename: Sander I
authors.initials: SI
authors.lastname: van Kasteren
authors.forename: Ilana
authors.initials: I
authors.lastname: Berlin
authors.forename: Jeff D
authors.initials: JD
authors.lastname: Colbert
authors.forename: Doreen
authors.initials: D
authors.lastname: Keane
authors.forename: Huib
authors.initials: H
authors.lastname: Ovaa
authors.forename: Colin
authors.initials: C
authors.lastname: Watts
mesh_terms: D015891:Cystatins / Q000737:chemistry; D057056:Cysteine Proteases / Q000378:metabolism; D010450:Endopeptidases / Q000378:metabolism; D008247:Lysosomes / Q000187:drug effects* / Q000201:enzymology / Q000502:physiology; D010436:Pepstatins / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D011480:Protease Inhibitors / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D013329:Structure-Activity Relationship
chemical_list: D015891:Cystatins; D010436:Pepstatins; D011480:Protease Inhibitors; D057056:Cysteine Proteases; D010450:Endopeptidases; C031375:pepstatin