Localization of Rat Cathepsin K in Osteoclasts and Resorption Pits: Inhibition of Bone Resorption and Cathepsin K-Activity by Peptidyl Vinyl Sulfones
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L. Xia
Abstract
We have localized cathepsin K in rat osteoclasts and within exposed resorption pits by immuno-fluorescence microscopy. Intracellular staining using an antibody raised against recombinant mouse cathepsin K was vesicular and uniformly distributed throughout the cell. Confocal microscopy analysis did not reveal an accumulation of cathepsin K containing vesicles opposing the ruffled border and the resorption lacuna. Exposed resorption pits exhibited a uniform distribution of cathepsin K, and no differences were observed between the edges and the centers of the pits. The immunostaining of resorption pits with anti-cathepsin K antibodies demonstrates that the protease is secreted into the sub-osteoclastic compartment.
Cathepsin K-specific inhibition using peptidyl vinyl sulfones as selective cysteine protease inactivators reduced bone resorption by 80% in a dose-dependent manner at sub-micromolar concentrations. No reduction of bone resorption was observed at those low concentrations using a potent cathepsin L, S, B-specific inhibitor. That the inhibition of bone resorption can be attributed to cathepsin K-like protease inhibition was corroborated by the selective inhibition of the osteoclastic Z-Gly-Pro-Arg-MβNA hydrolyzing activity by the cathepsin K, L, S, B-inhibitor, but not by the cathepsin L, B, and S inhibitor. Z-Gly-Pro-Arg-MβNA is efficiently hydrolyzed by cathepsin K but only poorly by cathepsins L, S, and B. On the contrary, the intracellular hydrolysis of the cathepsin B-specific substrate, Z-Arg-Arg-MβNA, was prevented by both types of inhibitors.
The identification of cathepsin K in resorption pits and the inhibition of bone resorption and intracellular cathepsin K activity by selective vinyl sulfone inhibitors indicate the critical role of the protease in osteoclastic bone resorption.
Copyright © 1999 by Walter de Gruyter GmbH & Co. KG
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Articles in the same Issue
- To Our Authors, Readers and Subscribers
- Michael Strauss. January 12, 1950 April 29, 1999
- Monoallelic Expression of Pax5: A Paradigm for the Haploinsufficiency of Mammalian Pax Genes?
- Adeno-Associated Viral Vectors for Gene Transfer and Gene Therapy
- Histidyl-tRNA Synthetase
- Dequalinium TM Vesicles Form Stable Complexes with Plasmid DNA which Are Protected from DNase Attack
- On the Role of Thymopoietins in Cell Proliferation. Immunochemical Evidence for New Members of the Human Thymopoietin Family
- Functional Characterization of Atherosclerosis-Associated Ser128Arg and Leu554Phe E-Selectin Mutations
- Cycloheximide, a New Tool to Dissect Specific Steps in ER-Associated Degradation of Different Substrates
- Localization of Rat Cathepsin K in Osteoclasts and Resorption Pits: Inhibition of Bone Resorption and Cathepsin K-Activity by Peptidyl Vinyl Sulfones
- Oxidation of 4-tert-Butylcatechol and Dopamine by Hydrogen Peroxide Catalysed by Horseradisch Peroxidase
- A Non-Radioactive Method for Inexpensive Quantitative RT-PCR
- Activation of the Transcription Factor ISGF3 by Interferon-gamma
- Acquisition of Myogenic Specificity through Replacement of One Amino Acid of MASH-1 and Introduction of an Additional alpha -Helical Turn
- The Heavy Metal-Responsive Transcription Factor-1 (MTF-1) Is Not Required for Neural Differentiation
- Human Fc gamma Receptor IIb Expressed in <I>Escherichia coli</I> Reveals IgG Binding Capability
- Mutational Analysis of Two Stefin A Epitopes
