Regulation of Collagenase Activities of Human Cathepsins by Glycosaminoglycans

Florida Atlantic University, Boca Raton, Florida, United States
Journal of Biological Chemistry (Impact Factor: 4.57). 03/2004; 279(7):5470-9. DOI: 10.1074/jbc.M310349200
Source: PubMed


Cathepsin K, a lysosomal papain-like cysteine protease, forms collagenolytically highly active complexes with chondroitin
sulfate and represents the most potent mammalian collagenase. Here we demonstrate that complex formation with glycosaminoglycans
(GAGs) is unique for cathepsin K among human papain-like cysteine proteases and that different GAGs compete for the binding
to cathepsin K. GAGs predominantly expressed in bone and cartilage, such as chondroitin and keratan sulfates, enhance the
collagenolytic activity of cathepsin K, whereas dermatan, heparan sulfate, and heparin selectively inhibit this activity.
Moreover, GAGs potently inhibit the collagenase activity of other cysteine proteases such as cathepsins L and S at 37 °C.
Along this line MMP1-generated collagen fragments in the presence of GAGs are stable against further degradation at 28 °C
by all cathepsins but cathepsin K, whereas thermal destabilization at 37 °C renders the fragments accessible to all cathepsins.
These results suggest a novel mechanism for the regulation of matrix protein degradation by GAGs. It further implies that
cathepsin K represents the only lysosomal collagenolytic activity under physiologically relevant conditions.

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    • "At acidic pH, chondroin-4-sulfate (C4S), chondroitin-6-sulfate (C6S) and keratan sulfate were shown to potentiate the collagenolytic activity of cathepsin K, with C4S being the most potent GAG species. Conversely, dermatan sulfate, heparan sulfate and HP inhibited the degradation of collagens (Li et al. , 2004 ; Wilson et al. , 2009 ). Curiously, the effects of C4S, C6S and dermatan sulfate on cathepsin K were virtually identical when enzyme activity was measured using a small synthetic substrate, resulting in a two-fold increase in the k cat / K m value (Li et al. , 2000 ). "
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    ABSTRACT: Abstract Cathepsin K has emerged as a promising target for the treatment of osteoporosis in recent years. Initially identified as a papain-like cysteine peptidase expressed in high levels in osteoclasts, the important role of this enzyme in bone metabolism was highlighted by the finding that mutations in the CTSK gene cause the rare recessive disorder pycnodysostosis, which is characterized by severe bone anomalies. At the molecular level the physiological role of cathepsin K is reflected by its unique cleavage pattern of type I collagen molecules which is fundamentally different from that of other endogenous collagenases. Several cathepsin K inhibitors have been developed to reduce excessive bone matrix degradation associated with osteoporosis, with the frontrunner odanacatib about to successfully conclude phase 3 clinical trials. Apart from osteoclasts, cathepsin K is expressed in different cell types throughout the body and is involved in processes of adipogenesis, thyroxine liberation and peptide hormone regulation. Elevated activity of cathepsin K has been associated with arthritis, atherosclerosis, obesity, schizophrenia, and tumor metastasis. Accordingly, its activity is tightly regulated via multiple mechanisms, including competitive inhibition by endogenous macromolecular inhibitors and allosteric regulation by glycosaminoglycans. This review provides a state-of-the-art description of the activity of cathepsin K at the molecular level, its biological functions and the mechanisms involved in its regulation.
    Full-text · Article · Apr 2013 · Biological Chemistry
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    • "CTSH digestion was performed at 1 mM CTSH in 0.05 mM sodium acetate, 10 mM ethylenediaminetetraacetic acid (EDTA) and 1 mM L-cysteine HCL Monohydrate at pH 5.5 [49]. CTSK digestion was performed at 1.83 mM CTSK in 50 mM sodium acetate, 2 mM DTT, 2 mM EDTA acid and 350 mM sodium chloride at pH 7.0 [50]. Digestion experiments were performed over a time course of 0, 2, 4, 8, 12 and 24 hours. "
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    ABSTRACT: Tumstatin is an anti-angiogenic collagen IV α3 fragment, levels of which are reduced in the airways of asthmatics. Its reduction may be due to the degradation by extracellular matrix (ECM) proteases. Cathepsins play a role in ECM remodelling, with cathepsin D, H and K (CTSD, CTSH and CTSK) being associated with lung diseases. CTSD modulates the NC1 domains of collagen molecules including tumstatin, while CTSH and CTSK are involved in ECM degradation. The role of these cathepsins in the regulation of tumstatin in the lung has not previously been examined. We demonstrated that CTSB, D, F, H, K, L and S mRNA was expressed in the airways. Quantification of immunohistochemistry showed that there is no difference in the global expression of CTSD, CTSH and CTSK between asthmatics and non-asthmatics. CTSD and CTSK, but not CTSH had the capacity to degrade tumstatin. No difference was observed in the activity of CTSD and H in bronchoalveolar lavage fluid of asthmatic and non-asthmatics, while CTSK was undetectable. This indicates that while CTSD possesses the potential to directly regulate tumstatin, and thus angiogenesis through this mechanism however, it is not likely to be involved in the dysregulation of tumstatin found in asthmatic airways.
    Full-text · Article · Mar 2013 · PLoS ONE
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    • "Some of them, such as chondroitin and keratan sulfate, enhance the collagenolytic activity of cathepsin K, whereas heparan sulfate or heparin selectively inhibits this activity. Moreover, GAGs potentially inhibit the collagenase activity of cathepsins L and S [53]. In addition, the specific inhibition of the collagenase activity of cathepsin K by negatively charged polymers, such as polyglutamates and oligonucleotides, without affecting the overall proteolytic activity of the protease was observed [54]. "
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    ABSTRACT: It is more than 50 years since the lysosome was discovered. Since then its hydrolytic machinery, including proteases and other hydrolases, has been fairly well identified and characterized. Among these are the cysteine cathepsins, members of the family of papain-like cysteine proteases. They have unique reactive-site properties and an uneven tissue-specific expression pattern. In living organisms their activity is a delicate balance of expression, targeting, zymogen activation, inhibition by protein inhibitors and degradation. The specificity of their substrate binding sites, small-molecule inhibitor repertoire and crystal structures are providing new tools for research and development. Their unique reactive-site properties have made it possible to confine the targets simply by the use of appropriate reactive groups. The epoxysuccinyls still dominate the field, but now nitriles seem to be the most appropriate "warhead". The view of cysteine cathepsins as lysosomal proteases is changing as there is now clear evidence of their localization in other cellular compartments. Besides being involved in protein turnover, they build an important part of the endosomal antigen presentation. Together with the growing number of non-endosomal roles of cysteine cathepsins is growing also the knowledge of their involvement in diseases such as cancer and rheumatoid arthritis, among others. Finally, cysteine cathepsins are important regulators and signaling molecules of an unimaginable number of biological processes. The current challenge is to identify their endogenous substrates, in order to gain an insight into the mechanisms of substrate degradation and processing. In this review, some of the remarkable advances that have taken place in the past decade are presented. This article is part of a Special Issue entitled: Proteolysis 50 years after the discovery of lysosome.
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