Increased activities of cathepsin B and other lysosomal hydrolases in fibroblasts and bone tissue cultured in the presence of cysteine proteinases inhibitors

Montenez, J P; Delaissé, Jean‐Marie; Tulkens, Paul M.; Kishore, Bellamkonda

doi:10.1016/0024-3205(94)00659-8

Cited by 23 publications

(12 citation statements)

References 25 publications

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“…Thus, as previously described [25], cycloheximide alone decreased the activity of cathepsin B to 20% of the control values. Co-incubation with azithromycin did not affect this decrease.…”

Section: Resultssupporting

confidence: 86%

“…The latter also causes an increase of lysosomal enzyme activities in cells cultivated in its presence but by impairing their breakdown [25], and its effect is therefore not antagonized by cycloheximide. This difference of behavior therefore suggests that azithromycin exerts its effect not in the lysosomes but probably at some step during the processing and packaging of the lysosomal enzymes, which is protein synthesis-dependent.…”

Section: Discussionmentioning

confidence: 99%

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Hyperactivity of cathepsin B and other lysosomal enzymes in fibroblasts exposed to azithromycin, a dicationic macrolide antibiotic with exceptional tissue accumulation

et al. 1996

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Azithromycin accumulates in lysosomes where it causes phospholipidosis. In homogenates prepared by sonication of fibroblasts incubated for 3 days with azithromycin (66 pM), the activities of sulfatase A, phospholipase AI, N-acetyl-~-hexosaminidase and cathepsin B increased from 180 to 330%, but not those of 3 non-lysosomal enzymes. The level of cathepsin B mRNA was unaffected. The hyperactivity induced by azithromycin is non-reversible upon drug withdrawal, prevented by coincubation with cycloheximide, affects the Vmax but not the Am, and is not reproduced with gentamicin, another drug also causing lysosomal phospholipidosis. The data therefore suggest that azithromycin increases the level of lysosomal enzymes by a mechanism distinct from the stimulation of gene expression but requiring protein synthesis, and is not in direct relation to the lysosomal phospholipidosis.

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“…Thus, as previously described [25], cycloheximide alone decreased the activity of cathepsin B to 20% of the control values. Co-incubation with azithromycin did not affect this decrease.…”

Section: Resultssupporting

confidence: 86%

Section: Discussionmentioning

confidence: 99%

Hyperactivity of cathepsin B and other lysosomal enzymes in fibroblasts exposed to azithromycin, a dicationic macrolide antibiotic with exceptional tissue accumulation

et al. 1996

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“…3). Previous reports have shown that both nonselective, nonbasic cysteine cathepsin inhibitors (Kominami et al, 1987;Montenez et al, 1994) and lysosomotropic compounds, such as chloroquine (Gerard et al, 1988;Gerbaux et al, 1996), induce an increase of cathepsin and other lysosomal protein levels in both isolated cells and in vivo. The formation of a protein-ligand complex often results in protein stabilization toward thermal and chaotropic agent denaturation (Kleanthous et al, 1991), as well as protease susceptibility .…”

Section: Discussionmentioning

confidence: 99%

Effect of Cathepsin K Inhibitor Basicity on in Vivo Off-Target Activities

Desmarais

Black²,

Oballa³

et al. 2007

Mol Pharmacol

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Cathepsin K is a lysosomal cysteine protease that is a pharmacological target for the treatment of osteoporosis. Previous studies showed that basic, lipophilic cathepsin K inhibitors are lysosomotropic and have greater activities in cell-based assays against cathepsin K, as well as the physiologically important lysosomal cysteine cathepsins B, L, and S, than expected based on their potencies against these isolated enzymes. Long-term administration of the basic cathepsin K inhibitors N- (1-(((cyanomethyl) -006235) and balicatib to rats at a supratherapeutic dose of 500 mg/kg/day for 4 weeks resulted in increased tissue protein levels of cathepsin B and L but had no effect on cathepsin B and L message. This is attributed to the inhibitor engagement of these off-target enzymes and their stabilization to proteolytic degradation. No such increase in these tissue cathepsins was detected at the same dose of, a potent nonbasic cathepsin K inhibitor with a similar off-target profile, although all three inhibitors provided similar plasma exposures. Using an activity-based probe, 125 I-BIL-DMK, in vivo inhibition of cathepsins B, L, and S was detected in tissues of mice given a single oral dose of L-006235 and balicatib, but not in mice given L-873724. In each case, similar tissue levels were achieved by all three compounds, thereby demonstrating the in vivo cathepsin selectivity of L-873724. In conclusion, basic cathepsin K inhibitors demonstrate increased off-target cysteine cathepsin activities than their nonbasic analogs and potentially have a greater risk of adverse effects associated with inhibition of these cathepsins.The CA1 family of human papain-like cysteine proteases comprises 11 members. These enzymes are collectively known as cathepsins, a name which is derived from the Greek kathepsein, to digest. Being largely lysosomal enzymes, cathepsins have acidic pH activity and stability optima. These enzymes are synthesized as preproenzymes, the mature proteins sharing between 25 and 80% sequence identity (Lecaille et al., 2002;Turk et al., 2003). Cathepsin K (Cat K) is highly and somewhat specifically expressed in osteoclasts, the multinucleated giant cells of hematopoietic origin that are responsible for the normal physiological process of bone resorption. Cat K destroys the organic fraction of bone through its potent collagenase activity, this process taking place in the acidic pit between the osteoclast and the bone surface and also intracellularly within lysosomes of the osteoclast (Saftig et al., 1998). A large volume of genetic and pharmacological data points to a pivotal role for Cat K in bone resorption, and Cat K inhibitors are presently being evaluated in clinical trials as a treatment of osteoporosis, a disease characterized by an imbalance of bone resorption over bone formation (performed by osteoblasts) (Deaton and Tavares, 2005;Grabowskal et al., 2005;Yasuda et al., 2005;Boyce et al., 2006;Close et al., 2006). Both physiological and pathological roles have been identified for the remaining 10 ...

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“…However, the important question of possible upregulation of cathepsins B, L, or S in cathepsin K-deficient osteoclasts has not been answered. Interestingly, the levels of cathepsins B, H, L, and other lysosomal enzymes such as TRAP, increase upon treatment with cysteine proteinase inhibitors (Kominami et al, 1987;Montenez et al, 1994). Furthermore, cathepsin L levels increase in osteoclasts upon stimulation by a series of bone-resorbing agents, and antisense oligodeoxynucleotides for cathepsin L inhibit the resorption of calvariae cultured in the presence of these bone-resorbing agents (Furuyama and Fujisawa, 2000).…”

Section: Bone Matrix Solubilization Is Still Possible Inmentioning

confidence: 95%

Matrix metalloproteinases (MMP) and cathepsin K contribute differently to osteoclastic activities

Delaissé

Andersen

Engsig

et al. 2003

Microscopy Res & Technique

287

184

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The best established proteolytic event of osteoclasts is bone matrix solubilization by the cysteine proteinase cathepsin K. Here, however, we draw the attention on osteoclastic activities depending on matrix metalloproteinases (MMPs). We discuss the observations supporting that MMPs contribute significantly to bone matrix solubilization in specific areas of the skeleton and in some developmental and pathological situations. Our discussion takes into account (1) the characteristics of the bone remodeling persisting in the absence of cathepsin K, (2) the ultrastructure of the resorption zone in response to inactivation of MMPs and of cathepsin K in different bone types, (3) bone resorption levels in MMP knockout mice compared to wild-type mice, (4) the identification of MMPs in osteoclasts and surrounding cells, and (5) the effect of different bone pathologies on the serum concentrations of specific collagen fragments believed to discriminate between cathepsin K and MMP cleavage. Next, we provide evidence that MMPs are very critical for osteoclast migration, thereby controlling also the cell-matrix interactions required for cell attachment/detachment. The evidence supporting this role is based on a model of osteoclast recruitment in primitive long bones, an assay of osteoclast invasion through collagen gel, and the effect of proteinase inhibitors/knockouts in these models. Furthermore, we mention observations indicating a role of MMPs in initiation of bone resorption. Finally, we emphasize the many distinct ways MMPs may alter focally the extracellular environment thereby regulating the osteoclast behavior. Although the understanding of MMPs in osteoclast biology is rapidly expanding, it is suspected that important roles remain to be discovered.

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Increased activities of cathepsin B and other lysosomal hydrolases in fibroblasts and bone tissue cultured in the presence of cysteine proteinases inhibitors

Cited by 23 publications

References 25 publications

Hyperactivity of cathepsin B and other lysosomal enzymes in fibroblasts exposed to azithromycin, a dicationic macrolide antibiotic with exceptional tissue accumulation

Hyperactivity of cathepsin B and other lysosomal enzymes in fibroblasts exposed to azithromycin, a dicationic macrolide antibiotic with exceptional tissue accumulation

Effect of Cathepsin K Inhibitor Basicity on in Vivo Off-Target Activities

Matrix metalloproteinases (MMP) and cathepsin K contribute differently to osteoclastic activities

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