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    Human chronic kidney allograft rejection is accompanied by increased intraglomerular cathepsin B and L activity
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    The ability of benzyloxycarbonyl-(125I)Tyr-Ala-CHN2 to label cysteine proteinases in a variety of human tissues was investigated. The inhibitor bound only to cathepsin B in tissues homogenized at pH 5.0. When liver was autolysed at pH 4.0 for up to 4 h, the inhibitor also bound to a protein of Mr 25,000. This was identified immunologically and chromatographically as cathepsin L. Both cathepsins B and L were found primarily in kidney, liver and spleen. In spleen, an additional protein of Mr 25,000 was also labelled. This protein could not be precipitated by antibodies to any of cathepsins B, H and L. This protein has tentatively been identified as human cathepsin S by its tissue distribution, chromatographic properties and molecular size. This work clearly shows that peptidyldiazomethanes are specific probes for cysteine proteinases, and that benzyloxycarbonyl-(125I)Tyr-Ala-CHN2 binds to three such enzymes in human tissues.
    Cathepsin L
    Cathepsin H
    Citations (31)
    Cathepsin B, a cysteine protease, is an important target in fighting cancer. This enzyme has been implicated in enhancing tumor invasiveness and metastasis, therefore inhibitors for cathepsin B are highly sought as potential anticancer and antimetastatic agents. A structure-based design effort was pursued in arriving at a template for inhibition of cathepsin B. Focused compound libraries were synthesized based on this template, which were screened for cathepsin B inhibitory properties. Compound 2, 1-(2(R)-{1(S)-acetoxy-2-[2(S)−(2,4-difluoro-benzoylamino)-3-phenyl-propionylaminooxy]-2-oxo-ethyl}-pentanoyl)-pyrrolidine-2(S)-carboxylic acid benzyl ester, is the prototype of this novel class of cysteine protease inhibitor that emerged from the search. The molecule modifies the active site of cathepsin B covalently, irreversibly, and efficiently, a process for which the kinetic parameters were evaluated. A set of three judiciously altered variants of compound 2 was also synthesized to explore the details of the proposed mechanism of action by this inhibitor. Compound 2 and its analogues may prove useful tools in reversing the deleterious effect of cathepsin B in fighting cancer.
    Cathepsin S
    Cysteine protease
    Cathepsin L
    Peptidomimetic
    Mechanism of Action
    Citations (37)
    The activities and contents of the lysosomal cysteine proteinases cathepsins B, H and L were examined in xenografts of biopsied muscles transplanted from age-matched normal subjects and Duchenne-muscular-dystrophy (DMD) patients into nude mice. The activity of cathepsin B increased 9-fold and that of B-plus-L increased 24-fold in the first week after transplantation in normal muscle xenografts. By the third week, the activity of cathepsin B increased a total of 20-fold and B-plus-L increased to 36-fold the original level. The activity levels of cathepsin B, B-plus-L, H and D, and acid phosphatase in normal and DMD xenografts were not significantly different when compared 2 weeks after transplantation. However, the protein content of cathepsin B in DMD muscle xenografts was more than 3-fold that of normal xenografts at 2 weeks. The profile of cathepsin H activity in normal muscle xenografts was different than those of cathepsins B and B-plus-L. In the first week, the cathepsin H diminished sharply to about one-third of the biopsied muscle level and then, by 3 weeks after transplantation, it had increased slightly to about half the original level. The amount of endogenous cysteine-proteinase inhibitor changed in parallel with the activity of cathepsins B and B-plus-L. Cathepsins B and H, but not cathepsin L, were found immunohistochemically in regenerating muscle fibres of normal and DMD xenografts 2 weeks after transplantation. Staining of cathepsin B in DMD xenografts was slightly stronger than that in normal subjects. There was no immunostaining in degenerating or necrotic muscle fibres 2 weeks after transplantation. Western-blot analysis revealed that the cathepsin B band at 29 kDa was increased in normal xenografts 2 and 3 weeks after transplantation. Also, 2 weeks after transplantation the staining intensity of this band was slightly stronger in DMD xenografts than in normal xenografts. These results suggest that cathepsin B participates in the regeneration of transplanted muscle, both normal and DMD, and in the DMD muscle fibre-wasting processes, during regeneration.
    Cathepsin L
    Cathepsin S
    Citations (19)
    Cathepsin B is an abundant and ubiquitously expressed cysteine peptidase of the papain family. It is involved in many physiological processes, such as remodeling of the extracellular matrix (wound healing), apoptosis, and activation of thyroxine and renin. In addition to its physiological roles, cathepsin B is important in many pathological processes, such as inflammation, parasite infection and cancer, where it is highly up-regulated. In cancer patients, elevated cathepsin B activity correlates to poor therapy outcome. Therefore, it is not surprising that the use of cathepsin B inhibitors reduces both tumor cell motility and invasiveness in vitro. This review summarizes recent developments in cathepsin B inhibition. To date, numerous protein inhibitors of cathepsin B have been described, some of which are of endogenous origin and function as regulators of cathepsin B activity in the cell, such as the cystatins. In addition, some exogenous protein inhibitors of cathepsin B have been isolated from various natural sources, and the use of X-ray crystal structures of cathepsin B complexed with such protein inhibitors has resulted in the design and synthesis of many new small-molecular-weight compounds as inhibitors of cathepsin B. These synthetic compounds generally contain an electrophilic functionality that reacts with cathepsin B. In the present review, these inhibitors are divided according to their mechanisms of action, as reversible and irreversible, and then further subdivided into groups for their full descriptions.
    Cathepsin S
    Cathepsin H
    Cathepsin L1
    Cathepsin A
    Cathepsin C
    Cathepsin L
    Cathepsin E
    Cysteine Proteinase Inhibitors
    Citations (119)
    The expression of three lysosomal cysteine protease activities, cathepsins B, H, and L, was examined during differentiation of L6 rat myoblasts. Analyses of intracellular levels of these proteases in unfractionated homogenates prepared from cells at different stages of growth and in parallel HPLC-fractionated samples demonstrated a fusion-related increase in all three cathepsins. Analyses of total levels of endogenous inhibitor activity against purified cathepsin B demonstrated a threefold increase in the ratio of protease to inhibitor during myoblast-myotube formation; however, levels of inhibitor activity remained constant. Extracellular levels of cathepsin B, H, and L activities were also examined in the serum-free defined media of differentiating L6 cells. These studies demonstrated a fusion-related increase in extracellular levels of acid/pepsin-activated (i.e., latent) cathepsin L. While increases in intracellular and extracellular levels of cathepsin activities were temporally related to the fusion process, fusion may not be a prerequisite for increased expression, since the nonfusing L6 variant L6-D3 demonstrated high levels of intracellular cathepsins B and L and extracellular latent cathepsin L activities throughout growth. Taken together, these results support the hypotheses that fusion or fusion-related processes play an important role in the controlled expression of cathepsins in L6 myoblasts and that cathepsins, in turn, play an important role in myoblast-myotube differentiation.Key words: L6 myoblasts, differentiation, lysosomal cysteine proteases.
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    Cysteine cathepsins are expressed in most tissues, including the gastrointestinal tract. We demonstrated an involvement of mouse intestinal cathepsin B in extracellular matrix remodeling for regeneration from trauma. The present study aimed at elucidating roles of cysteine cathepsins in the non-traumatized gastrointestinal tract of mice. Thus we investigated expression and localization patterns of cathepsin B and its closest relative, cathepsin X, along the length of the gastrointestinal tract, and determined the effects of their absence. Cathepsin B showed the highest protein levels in the anterior segments of the gastrointestinal tract, whereas the highest activity was observed in the jejunum, as revealed by cathepsin B-specific activity-based probe labeling. Cathepsin X was most abundant in the jejunum and protein levels were elevated in duodenum and colon of Ctsb-/- mice. The segmental pattern of cathepsin expression was reflected by a compartmentalized distribution of junction proteins and basal lamina constituents, changes in tissue architecture and altered activities of the brush border enzyme aminopeptidase N. In conclusion, we observed different compensatory effects and activity levels of cysteine peptidases along the length of the small and large intestines in a segment-specific manner suggesting specific in situ functions of these enzymes in particular parts of the gastrointestinal tract.
    Cathepsin H
    Jejunum
    Cathepsin L
    Cathepsin A
    Cathepsin C
    Citations (10)
    The cathepsin family of endosomal proteases is required for proteolytic processing of several viruses during entry into host cells. Mammalian reoviruses utilize cathepsins B (Ctsb), L (Ctsl), and S (Ctss) for disassembly of the virus outer capsid and activation of the membrane penetration machinery. To determine whether cathepsins contribute to reovirus tropism, spread, and disease outcome, we infected 3-day-old wild-type (wt), Ctsb(-/-), Ctsl(-/-), and Ctss(-/-) mice with the virulent reovirus strain T3SA+. The survival rate of Ctsb(-/-) mice was enhanced in comparison to that of wt mice, whereas the survival rates of Ctsl(-/-) and Ctss(-/-) mice were diminished. Peak titers at sites of secondary replication in all strains of cathepsin-deficient mice were lower than those in wt mice. Clearance of the virus was delayed in Ctsl(-/-) and Ctss(-/-) mice in comparison to the levels for wt and Ctsb(-/-) mice, consistent with a defect in cell-mediated immunity in mice lacking cathepsin L or S. Cathepsin expression was dispensable for establishment of viremia, but cathepsin L was required for maximal reovirus growth in the brain. Treatment of wt mice with an inhibitor of cathepsin L led to amelioration of reovirus infection. Collectively, these data indicate that cathepsins B, L, and S influence reovirus pathogenesis and suggest that pharmacologic modulation of cathepsin activity diminishes reovirus disease severity.
    Cathepsin L
    Cathepsin L1
    Cathepsin S
    Pathogenesis
    Citations (30)
    A series of peptidyldiazomethanes was synthesized and tested as inactivators of the cysteine proteinases calpain II, cathepsin L and cathepsin B. Inactivators that react rapidly and that show a degree of selectivity between the enzymes were identified. Z-Tyr(I)-Ala-CHN2 (where Z represents benzyloxycarbonyl) reacts rapidly with cathepsin L and more slowly with cathepsin B, but does not inhibit calpain II. Z-Leu-Leu-Tyr-CHN2 reacts rapidly with cathepsin L and calpain II but very slowly with cathepsin B. Boc-Val-Lys(epsilon-Z)Leu-Tyr-CHN2 (where Boc represents t-butyloxycarbonyl) reacts more rapidly with calpain II than with cathepsin L or cathepsin B. The discriminating inhibitory effects of these compounds make them potentially useful for investigation of enzyme functions in vivo. The data presented also provide insights into the subsite specificity of calpain.
    Cathepsin S
    Cathepsin L
    Cathepsin H
    Cathepsin A
    Cathepsin L1
    Cathepsin E
    Cysteine Proteinase Inhibitors
    Cathepsin C
    Citations (139)