Disease relevance of CTSB

• The structure of the compound seemed to be responsible for the effects measured since compounds used to represent constituents of Zeolite A (silicon dioxide and aluminum chloride) failed to inhibit bone resorption or reduce the level of secreted cathepsin B enzyme activity [1].
• Breast muscle (BM) weight, leg muscle (LM) weight, whole body weight, and BM and LM cathepsin B and L activities were obtained on 12 birds/treatment [2].

High impact information on CTSB

• At higher concentrations (10-100 mM), the chymotrypsin substrates N alpha-p-tosyl-L-arginine methyl ester and tryptophan methyl ester and the cathepsin B inhibitor leupeptin also inhibit [3H] 1,25(OH)2D3 binding to its receptor [3].
• Osteoclasts were transiently transfected and secretions of cathepsin B/K and tartrate-resistant acid phosphatase (TRAP) were monitored [4].
• In basal-lateral membranes, enhanced CB activity was detectable 10 h after 1,25(OH)2D3 in vivo, rose to 155% of -D levels at 15 h, and to 245% of controls in fractions from +D birds, whereas acid phosphatase was 75%, 81%, and 125% of controls, respectively, at these times.(ABSTRACT TRUNCATED AT 250 WORDS)[5]
• Peptidyl acyloxymethyl ketones, previously established as potent inactivators of the lysosomal cysteine proteinase cathepsin B, were evaluated against smooth-muscle calpain, a member of the family of Ca(2+)-dependent cysteine proteinases [6].
• Ki values for the inhibition of cysteine proteinases were as follows: papain (less than 1 X 10(-11)M), cathepsin B (8 X 10(-10)M), cathepsin H (about 2 X 10(-8)M) and cathepsin L (about 3 X 10(-12)M) [7].

Biological context of CTSB

• Overlapping cDNA fragments encoding avian cathepsin B were cloned from an osteoclast cDNA library and sequenced [8].
• The NH2-terminal amino acid sequence of the enzyme was similar to that of chicken cathepsin B. These characteristics indicate that the purified enzyme is a member of the cysteine proteinase family [9].

Anatomical context of CTSB

• In osteoclasts and cultured macrophages, which produce large quantities of cathepsin B, mRNAs of 1.8 and 2.4 kb are produced in approximately equal quantities, while cells producing smaller quantities of the enzyme produce predominantly the 2.4 kb form [8].
• After 30 min of calcium transport, endocytic vesicles prepared from either vitamin D-deficient or 1,25(OH)2D3-treated birds had recovered cathepsin B activity to pretransport levels [10].
• In sections prepared after 3 min of calcium absorption, cathepsin B staining was localized near the basal and lateral membranes of the epithelial cells [10].
• In the absence of calcium transport, cathepsin B-specific activity was enhanced in whole homogenates, endocytic vesicles, and a lysosomal fraction prepared from intestinal epithelium of 1,25(OH)2D3-treated chicks, relative to vitamin D-deficient controls [10].
• Hybridization of RNA extracted from the L6 myogenic cell line with cathepsin B cDNA showed an increase in the level of cathepsin B mRNA [11].

Associations of CTSB with chemical compounds

• They are all collagen-degrading cysteine proteinases, with Mr values of 25,250, 23,500, 34,000 and 30,000 for cathepsin B, L, N and S respectively [12].
• Proteolysis of liver acetyl coenzyme A carboxylase by cathepsin B [13].
• The protease was inhibited by leupeptin, which is known to be a strong inhibitor of papain, cathepsin B, trypsin, and plasmin [14].
• Neither were cathepsin B and B + L activities affected by T3 or T4 [15].
• Ubiquitin and proteasome subunits (C1 and C2) and calpains (m-, mu-, and p94/calpain-3) but not cathepsin B mRNA expression were increased by serum deprivation [16].

Other interactions of CTSB

• In the present study, we examined the effect of serum deprivation on expression of the proteolytic-related genes (ubiquitin, proteasome, calpains, and cathepsin B) by real-time PCR of cDNA in chick myotubes [16].
• Recombinant Q53E- and Q53N--chicken egg white cystatin variants inhibit papain, actinidin and cathepsin B [17].

Analytical, diagnostic and therapeutic context of CTSB

• Thus, biochemical analysis of cathepsin B activity in putative endocytic vesicles and lysosomes supports the intracellular redistribution of protease visualized with immunofluorescence microscopy [10].

References