Autocatalytic processing of procathepsin B is triggered by proenzyme activity. FEBS J. 276, 660-668

Department of Biochemistry and Molecular and Structural Biology, Jozef Stefan Institute, Ljubljana, Slovenia.
FEBS Journal (Impact Factor: 4). 03/2009; 276(3):660-8. DOI: 10.1111/j.1742-4658.2008.06815.x
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Cathepsin B (EC and other cysteine proteases are synthesized as zymogens, which are processed to their mature forms autocatalytically or by other proteases. Autocatalytic processing was suggested to be a bimolecular process, whereas initiation of the processing has not yet been clarified. Procathepsin B was shown by zymography to hydrolyze the synthetic substrate 7-N-benzyloxycarbonyl-L-arginyl-L-arginylamide-4-methylcoumarin (Z-Arg-Arg-NH-MEC), suggesting that procathepsin B is catalytically active. The activity-based probe DCG-04, which is an E-64-type inhibitor, was found to label both mature cathepsin B and its zymogen, confirming the zymography data. Mutation analyses in the linker region between the propeptide and the mature part revealed that autocatalytic processing of procathepsin B is largely unaffected by mutations in this region, including mutations to prolines. On the basis of these results, a model for autocatalytic activation of cysteine cathepsins is proposed, involving propeptide dissociation from the active-site cleft as the first step during zymogen activation. This unimolecular conformational change is followed by a bimolecular proteolytic removal of the propeptide, which can be accomplished in one or more steps. Such activation, which can be also facilitated by glycosaminoglycans or by binding to negatively charged surfaces, may have important physiological consequences because cathepsin zymogens were often found secreted in various pathological states.

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    • "Exceptionally, CatS, remains catalytically active under neutral pH and remains stable outside the lysosome. Like CatB and CatL, CatS undergoes autoactivation (Pungercar et al., 2009). Interestingly , glycosaminoglycans promote the autocatalytic processing of cathepsins to their mature forms (Caglic et al., 2007). "
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    ABSTRACT: Dyslipemia has a direct impact on cardiac remodeling by altering extracellular matrix (ECM) components. One of the main ECM components is elastin, a proteic three-dimensional network that can be efficiently degraded by cysteine proteases or cathepsins. Dyslipemic status in insulin resistance and combined hyperlipoproteinemia diseases include raised levels of very low density lipoproteins (VLDL), triglyceride (TG)-cholesteryl ester (CE)-rich lipoproteins. Enhanced VLDL concentration promotes cardiomyocyte intracellular cholesteryl ester (CE) accumulation in a LRP1-dependent manner. The aim of this work was to analyze the effect of cardiomyocyte intracellular CE accumulation on tropoelastin (TE) characteristics and to investigate the role of LRP1 and Cathepsin S (CatS) on these effects. Molecular studies showed that LRP1 deficiency impared CE selective uptake and accumulation from TG-CE- rich lipoproteins (VLDL+IDL) and CE-rich lipoproteins (aggregated LDL, agLDL). Biochemical and confocal microscopic studies showed that LRP1-mediated intracellular CE accumulation increased CatS mature protein levels and induced an altered intracellular TE globule structure. Biophysical studies evidenced that LRP1-mediated intracellular CE accumulation caused a significant drop of Tg2 glass transition temperature of cardiomyocyte secreted TE. Moreover, CatS deficiency prevented the alterations in TE intracellular globule structure and on TE glass transition temperature. These results demonstrate that LRP1-mediated cardiomyocyte intracellular CE accumulation alters the structural and physical characteristics of secreted TE through an increase in CatS mature protein levels. Therefore, the modulation of LRP1-mediated intracellular CE accumulation in cardiomyocytes could impact pathological ventricular remodeling associated with insulin-resistance and combined hyperlipoproteinemia, pathologies characterized by enhanced concentrations of TG-CE-rich lipoproteins.
    The International Journal of Biochemistry & Cell Biology 09/2014; 55. DOI:10.1016/j.biocel.2014.09.005 · 4.05 Impact Factor
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    • "Their activation can be autocatalytic or catalyzed by other proteases [14] [38]. However, even during autocatalytic activation, activation is always in trans, i.e. one cathepsin or procathepsin molecule activating another procathepsin molecule [39]. In contrast to endopeptidases , exopeptidases cathepsins C and X cannot be autocatalytically activated but require an endopeptidase such as cathepsin L or S for their activation [40] [41]. "
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    ABSTRACT: Cysteine cathepsins are normally found in the lysosomes where they are involved in intracellular protein turnover. Their ability to degrade the components of the extracellular matrix in vitro was first reported more than 25 years ago. However, cathepsins were for a long time not considered to be among the major players in ECM degradation in vivo. During the last decade it has, however, become evident that abundant secretion of cysteine cathepsins into extracellular milieu is accompanying numerous physiological and disease conditions, enabling the cathepsins to degrade extracellular proteins. In this review we will focus on cysteine cathepsins and their extracellular functions linked with ECM degradation, including regulation of their activity, which is often enhanced by acidification of the extracellular microenvironment, such as found in the bone resorption lacunae or tumor microenvironment. We will further discuss the ECM substrates of cathepsins with a focus on collagen and elastin, including the importance of that for pathologies. Finally, we will overview the current status of cathepsin inhibitors in clinical development for treatment of ECM-linked diseases, in particular osteoporosis. Due to their major role in ECM remodelling cysteine cathepsins have emerged as an important group of therapeutic targets for a number of ECM-related diseases, including, osteoporosis, cancer and cardiovascular diseases. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties..
    Biochimica et Biophysica Acta 03/2014; 1840(8). DOI:10.1016/j.bbagen.2014.03.017 · 4.66 Impact Factor
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    • "Procathepsin B was a pro-form of active mature form of cathepsin B (8,9) and could be suggested as a new tumour biomarker in ovarian cancer. "
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    ABSTRACT: To evaluate procathepsin B, as well as endogenous inhibitors of cysteine proteases (cystatin B and cystatin C) in biological fluids as possible biomarkers of ovarian cancer. To observe levels of serum procathepsin B in different age groups. The sample (N=27) of women with gynaecological tumours included 18 patients with ovarian cancer (n=18) and 9 patients with benign ovarian tumours (n=9); 72 healthy women were in the control group. All patients were treated in Novosibirsk Regional Oncological Center, Russia. Serum samples of healthy women (n=40) aged 18-70 years were used as controls for common biomarker of ovarian cancer CA-125. In the Procathepsin B study, serum samples of healthy women (n=32) aged 18-40 years (n=14), 41-55 years (n=10) and 56-80 (n=8) years were used as controls. Common biomarker of ovarian cancer, CA-125, was assayed by using a commercial kit (Vector, Koltsovo, Novosibirsk Region, Russia). Procathepsin B was measured by means of a commercial kit for human procathepsin B (R&D, USA); cystatin C was measured by commercial ELISA kits for human (BioVendor, Czechia); cystatin B was measured by ELISA kits for human (USCN Life Science Inc., Wuhan, China). Statistical analysis was performed by one-way ANOVA (Statistica 10 Program). In the control group, serum procathepsin B concentration did not reveal age dependency. In the ovarian cancer group, both levels of serum procathepsin B and standard biomarker CA-125 increased significantly (both p<0.001) compared with the control group. In the benign ovarian tumour group, serum procathepsin B (p<0.001) and CA-125 (p=0.004) increased about 2.5- and 8-fold compared to the control group. Serum cystatin B level increased up to 1.7-fold in the ovarian cancer group compared to the control group. The increase of serum CA-125 was about 3.5-fold higher (p=0.017) and procathepsin B was 1.8-fold higher (p<0.05) in the ovarian cancer group compared to the benign tumour group. Cystatin B in ascites fluid increased equally in both ovarian cancer (p<0.001) and benign ovarian tumours group (p<0.05). Cystatin C concentration in ascites fluid increased only in patients with ovarian cancer (p<0.05) and did not change in the benign tumours group. Large increases of procathepsin B level (about 13-fold, p<0.001) and to a lesser degree of cystatin C (1.8-fold, p<0.05) and cystatin B levels (1.4 fold, p<0.001) were revealed in ascites fluids of patients with ovarian cancer compared to the control serum. The significant difference in serum procathepsin B levels was noted between the ovarian cancer and benign tumour groups (p<0.05), which could be used in differential diagnostics between malignant and benign gynaecological tumours. Serum procathepsin B demonstrated significant promise as a new biomarker of ovarian cancer.
    08/2013; 72. DOI:10.3402/ijch.v72i0.21215
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