Atlas of Genetics and Cytogenetics in Oncology and Haematology

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CTSB (cathepsin B)


Other namesAPPS
LocusID (NCBI) 1508
Location 8p23.1
Location_base_pair Starts at 11700034 and ends at 11725646 bp from pter ( according to hg19-Feb_2009)  [Mapping]


Description The gene for human cathepsin B is located on chromosome 8p22 and it comprises 12 exons. The transcript length is 1017 bps which are translated to 339 residues preproenzyme. Cathepsin B mRNA consists of several variants produced by alternative exon splicing. Most variations involve the 5'- and 3'-UTR. Cathepsin B mRNAs lacking exon 2 are predominant in human tumours. In addition, human breast and colon carcinomas and human melanoma contain a cathepsin B transcript that is also missing exon 3 encoding the signal peptide and 7 residues of the activation propeptide.
Transcription Transcription is initiated from more than one promoter region. In addition to the promoter region upstream from exon 1, there could be promoters upstream from exons 3 and 4. Each promoter region could be regulated independently.


  Richardson diagram of procathepsin B structure: a-helixes are shown in red and β-sheets in green. Catalytic residues are shown in ball-and-stick representation: Cys108 in yellow, His278 in purple and Asn298 in pink. His189 on the occluding loop is shown in purple in ball-and-stick representation. The propeptide is shown in grey (MEROPS: the peptidase database - C01.060).
Description Cathepsin B belongs to the superfamily of papain-like cysteine proteases. It is synthesized as a preproenzyme of 339 amino acid residues with a calculated Mr of 37 822 Da. The presence of a signal sequence and N-glycosylation sites shows that cathepsin B is targeted to the endosomal/lysosomal compartment via the mannose-6-phosphate receptor pathway.
Under certain pathological conditions, cathepsin B is translocated to the peripheral cytoplasmic and plasma membrane region or secreted from cells. Processing to the mature enzyme form occurs in the acidic environment of the trans-Golgi and the lysosome. Procathepsin B can be activated by cathepsin D, elastase and cathepsins G, uPA/PLAU or tPA./PLAT Activation occurs by cleaving and dissociation of 62 residue proregion. The final proteolytic event is the cleavage between residues 47 and 50 to yield a two-chain form of the enzyme with the excision of a dipeptide. Access of substrate into the active site of cathepsin B is controlled by an 18-residue-long insertion (Pro 107­Asp 124), termed the occluding loop which provides two His residues to bind the carboxylic group of the C-terminus of the substrate. This explains the preferred carboxypeptidase activity of the enzyme.
However, cathepsin B can also act as an endopeptidase since the occluding loop is flexible and can move from the active site cleft when endopeptidase substrate binds to the enzyme. For colorimetric and fluorimetric assay of cathepsin B peptidyl-NHPhNO2 and ­NHMec substrates are most commonly used. When the selectivity for cathepsin B over other lysosomal cysteine peptidases such as cathepsin H, cathepsin L and cathepsin S is required, Z-Arg-Arg+ NHPhNO2 or Z-Arg-Arg+NHMec should be used.
Cathepsin B is inhibited by a2-macroglobulin, the cystatin family of inhibitors of papain-like cysteine peptidases and by the equistatin family. The displacement of the occluding loop is required for the binding of cystatin C to the active-site cleft. Most of the natural cysteine protease inhibitors are therefore much less effective against cathepsin B than other members of the papain family. Cathepsin B is susceptible to the various classes of irreversible inhibitors that have been developed for the papain family. Selectivity has been achieved through the synthesis of E-64 derivatives CA-074, CA-030 and isobutyl-epoxysuccinyl-Leu-Pro.
Expression Based on the structure of the mouse and human promoter regions, cathepsin B is classified as a housekeeping gene. Although this implies that the expression of the gene is constitutive, increases in the amounts of mRNA for cathepsin B have been reported in many human tumours. At the gene level, the altered expression results from gene amplification, elevated transcription, use of alternative promoters and alternative splicing. These molecular changes lead to increased cathepsin B protein levels and in turn redistribution, secretion and increased activity. Over-expression of cathepsin B has been reported in several human tumours including tumours of brain, colon, prostate and thyroid.
Localisation Cathepsin B asts as a lysosomal cysteine protease in normal cells and tissues. In malignant tumours and premalignant lesions, the expression of cathepsin B is highly up-regulated and the enzyme is secreted and becomes associated with the cell surface. Secretion of procathepsin B occurs principally as a result of increased expression, whereas secretion of active cathepsin B seems to be facilitated by lysosomal exocytosis or extracellular processing by surface activators. Cathepsin B is localized to caveolae on the tumour surface, where binding to the annexin II heterotetramer occurs. Activation of cathepsin B on the cell surface leads to the regulation of downstream proteolytic cascade(s). A truncated form of cathepsin B lacking the signal peptide and part of the propeptide, and encoded by the construct missing exons 2 and 3, was neither found in the Golgi apparatus nor in lysosomal vesicles, but rather in the cytoplasm as patches associated with membranous and short fibrillar elements.
Function In the lysosomes, cathepsin B is involved in the turnover of proteins and plays various roles in maintaining the normal metabolism of cells. Cathepsin B protein and activity levels have been found to be higher in many human tumours including tumours of breast, cervix and ovary, colon, stomach, glioma, lung and thyroid. The redistribution of cathepsin B to the cell surface in cancer cells occurs coincidently with degradation of the underlying extracellular matrix (ECM). Cathepsin B can affect ECM directly causing its proteolytic degradation or indirectly via activation or amplification of other ECM-degrading proteases. The endopeptidase activity of cathepsin B should be important in direct extra- or intra-cellular remodelling of ECM, since it is capable of degrading ECM proteins laminin, fibronectin, and collagen IV, facilitating tumour cell invasion and metastasis. Digestion of fibronectin results in exposure of the CS-1 sequence, which is recognized by the integrin receptor a4β1, linking cathepsin B to cellular signal transduction events. Cathepsin B indirectly enhances proteolysis by activating the urokinase-type pro-plasminogen which can subsequently activate the plasmin-metalloproteinases proteolytic pathway.
Moreover, cathepsin B may change the balance between metalloproteinases (MMP) and their inhibitors and directly activates some of the MMPs - interstitial procollagenase (proMMPs-3) and prostromelysin-1 (proMMPs-2), and cleaves and inactivates some of the MMP inhibitors TIMP-1 and TIMP-2. In such a way, cathepsin B assists tumour cells in their detachment from ECMs and metastasis. Moreover, during proteolytic breakdown of ECMs, some ECM-bound growth factors such as bFGF, EGF, TGF-β, IGF-I and VEGF may be liberated and become bioavailable for growth modulation of receptor-partner expressing tumour and stroma cells.
Homology Cathepsin B is encoded by a single gene in humans and other mammals and it exhibit a high degree of sequence homology to other cysteine proteinases of the papain superfamily. In contrast, cathepsin B-like cysteine protease genes occur as large multigene families in a wide range of parasitic helminths and free-living nematodes. Several cathepsin B-like genes were shown to be expressed in the intestine of the parasitic worm Haemonchus contortus or in the free-living nematode Caenorhabditis elegans. No function for any of the cathepsin B-like cysteine protease, has been resolved but it is believed that they are involved in induction of protective immunity.


Germinal not yet reported for Homo sapiens.
Somatic not yet reported for Homo sapiens.

Implicated in

Entity Invasive cancers
Disease Over-expression of cathepsin B mRNA has been reported in several human tumours including tumours of brain, colon, prostate and thyroid. However, increased expression of cathepsin B, in premalignant lesions, suggests that this enzyme may play a role in the transformation of pre-malignant lesions to malignant tumours. Moreover, it has been found that cathepsin B expression often increases specifically at the invasive edge of tumour cells. Although, a few studies indicate a correlation between cathepsin B mRNA over-expression and tumour invasion, numerous studies have been focused on cathepsin B expression at the level of protein and activity. Cathepsin B protein and activity levels have been found to be higher in many human tumours including tumours of breast, cervix and ovary, colon, stomach, bladder, glioma, lung, prostate and thyroid.
Prognosis Cathepsin B was shown to participate in processes of tumour growth, vascularisation, invasion and metastasis. Its level in tumour tissue extracts can provide useful clinical information to predict disease-free and overall survival in breast, prostate, lung, colorectal and other cancer patients. Cathepsin B expression correlated with the invasiveness, especially in malignant breast and prostate tumours. In melanoma and colorectal cancer patients high serum levels of cathepsins B correlated with shorter survival. It was found that both cysteine cathepsins and their endogenous protein inhibitors stefins and cystatin C can also predict prognosis when measured extracellularly. However, the cathepsin B/cystatin C complex was found to be less abundant in sera of patients with malignant tumours than in those with benign diseases or in healthy controls, suggesting an imbalance between the enzyme and its inhibitor in cancer patients.
Oncogenesis Cathepsin B can degrade components of the extracellular matrix (laminin, fibronectin and collagen IV) and intact basement membrane in vitro. In vivo studies have found that there is an inverse correlation between cathepsin B staining and basement membrane (type IV collagen or laminin) staining in bladder, gastric, lung and colon carcinomas. This would be consistent with a functional role for cathepsin B in degrading these extracellular matrix components in vivo.
Once activated, cathepsin B may activate pro-uPA, which then in turn can convert plasminogen to plasmin. Plasmin is capable of degrading several components of the extracellular matrix may activate MMPs such as interstitial collagenase (MMP-1), stromelysin-1 (MMP-3), gelatinase B (MMP-9), metalloelastase (MMP-12), and collagenase-3 (MMP-13). These MMPs can degrade many different components of the extracellular matrix and can activate other MMPs. Cathepsin B, in addition to indirectly activating MMPs via the plaminogen activator/plasmin cascade, may also directly activate MMPs, e.g., interstitial collagenase and stromelysin-1. In vitro assays, however, do not replicate the complex tumour environment and thus we are not sure if these interactions between proteases actually occur in vivo.
Entity Neurodegenerative diseases
Disease The regulated secretory pathway of neurons is the major source of toxic beta-amyloid peptides that accumulates in Alzheimer's disease. Extracellular beta-amyloid peptides secreted from that pathway is generated by beta-secretase processing of amyloid precursor protein. Previously, cysteine protease activity was demonstrated as the major beta-secretase activity in regulated secretory vesicles of neuronal chromaffin cells. The representative cysteine protease activity in these secretory vesicles was identified as cathepsin B. These results demonstrate a newly identified role for cathepsin B in neurosecretory vesicles in the production of biologically active peptides. Inhibitors of cathepsin B may be considered as therapeutic agents to reduce toxic beta-amyloid peptides in Alzheimer's disease.
Entity Cardiovascular diseases
Disease Cathepsin cysteine proteases have been shown to play a role in several cardiovascular diseases, including restenosis and neointima formation, aneurysm formation, and atherosclerosis. Cathepsin B is mainly expressed in macrophages, but also in smooth muscle cells and human umbilical venous endothelial cells. Its mRNA and protein levels were found to be increased in atherosclerotic lesions of apoE-deficient mice, and cathepsin B immunoreactivity was highest in areas next to the lumen and in macrophages. Relocation of cathepsin B from the lysosome into the cytosol, where it may act as cleavage enzymes in apoptosis, may eventually contribute to the formation of the necrotic core and can be considered an atherosclerosis-stimulating role. On the other hand, inhibition of cathepsin B reduced lysosomal degradation of modified LDL, thereby inducing foam cell formation, which can be regarded as an atherosclerosis-protective role for cathepsin B.

External links

HGNC (Hugo)CTSB   2527
Entrez_Gene (NCBI)CTSB  1508  cathepsin B
GeneCards (Weizmann)CTSB
Ensembl (Hinxton)ENSG00000164733 [Gene_View]  chr8:11700034-11725646 [Contig_View]  CTSB [Vega]
ICGC DataPortalENSG00000164733
Genatlas (Paris)CTSB
SOURCE (Princeton)NM_001908 NM_147780 NM_147781 NM_147782 NM_147783
Genomic and cartography
GoldenPath (UCSC)CTSB  -  8p23.1   chr8:11700034-11725646 -  8p23.1   [Description]    (hg19-Feb_2009)
EnsemblCTSB - 8p23.1 [CytoView]
Mapping of homologs : NCBICTSB [Mapview]
Gene and transcription
Genbank (Entrez)AK075393 AK092070 AK097384 AK130184 AK290239
RefSeq transcript (Entrez)NM_001908 NM_147780 NM_147781 NM_147782 NM_147783
RefSeq genomic (Entrez)AC_000140 NC_000008 NC_018919 NG_009217 NT_077531 NW_001839122 NW_004929336
Consensus coding sequences : CCDS (NCBI)CTSB
Cluster EST : UnigeneHs.520898 [ NCBI ]
CGAP (NCI)Hs.520898
Alternative Splicing : Fast-db (Paris)GSHG0029411
Alternative Splicing GalleryENSG00000164733
Gene ExpressionCTSB [ NCBI-GEO ]     CTSB [ SEEK ]   CTSB [ MEM ]
Protein : pattern, domain, 3D structure
UniProt/SwissProtP07858 (Uniprot)
NextProtP07858  [Medical]
With graphics : InterProP07858
Splice isoforms : SwissVarP07858 (Swissvar)
Catalytic activity : Enzyme3.4.22.1 [ Enzyme-Expasy ] [ IntEnz-EBI ] [ BRENDA ] [ KEGG ]   
Domaine pattern : Prosite (Expaxy)THIOL_PROTEASE_ASN (PS00640)    THIOL_PROTEASE_CYS (PS00139)    THIOL_PROTEASE_HIS (PS00639)   
Domains : Interpro (EBI)Pept_asp_AS [organisation]   Pept_cys_AS [organisation]   Pept_his_AS [organisation]   Peptidase_C1A [organisation]   Peptidase_C1A_C [organisation]   Propeptide_C1A [organisation]  
Related proteins : CluSTrP07858
Domain families : Pfam (Sanger)Peptidase_C1 (PF00112)    Propeptide_C1 (PF08127)   
Domain families : Pfam (NCBI)pfam00112    pfam08127   
Domain families : Smart (EMBL)Pept_C1 (SM00645)  
DMDM Disease mutations1508
Blocks (Seattle)P07858
PDB (SRS)1CSB    1GMY    1HUC    1PBH    2IPP    2PBH    3AI8    3CBJ    3CBK    3K9M    3PBH   
PDB (PDBSum)1CSB    1GMY    1HUC    1PBH    2IPP    2PBH    3AI8    3CBJ    3CBK    3K9M    3PBH   
PDB (IMB)1CSB    1GMY    1HUC    1PBH    2IPP    2PBH    3AI8    3CBJ    3CBK    3K9M    3PBH   
PDB (RSDB)1CSB    1GMY    1HUC    1PBH    2IPP    2PBH    3AI8    3CBJ    3CBK    3K9M    3PBH   
Human Protein AtlasENSG00000164733 [gene] [tissue] [antibody] [cell] [cancer]
Peptide AtlasP07858
IPIIPI00295741   IPI01009733   IPI00909303   IPI01014579   IPI00978088   IPI01011636   IPI00978678   IPI00984553   IPI00983365   IPI00983480   IPI00982855   IPI00982206   IPI00980515   IPI00976781   IPI00981711   IPI00975638   IPI00976313   IPI00984007   IPI00984542   
Protein Interaction databases
IntAct (EBI)P07858
Interologous Interaction database P07858
Ontologies - Pathways
Ontology : AmiGOtoll-like receptor signaling pathway  cysteine-type endopeptidase activity  protein binding  extracellular region  extracellular space  intracellular  nucleolus  mitochondrion  lysosome  proteolysis  peptidase activity  cysteine-type peptidase activity  extracellular matrix disassembly  extracellular matrix organization  collagen catabolic process  endolysosome lumen  melanosome  regulation of apoptotic process  intracellular membrane-bounded organelle  innate immune response  perinuclear region of cytoplasm  regulation of catalytic activity  cellular response to thyroid hormone stimulus  
Ontology : EGO-EBItoll-like receptor signaling pathway  cysteine-type endopeptidase activity  protein binding  extracellular region  extracellular space  intracellular  nucleolus  mitochondrion  lysosome  proteolysis  peptidase activity  cysteine-type peptidase activity  extracellular matrix disassembly  extracellular matrix organization  collagen catabolic process  endolysosome lumen  melanosome  regulation of apoptotic process  intracellular membrane-bounded organelle  innate immune response  perinuclear region of cytoplasm  regulation of catalytic activity  cellular response to thyroid hormone stimulus  
Pathways : KEGGLysosome    Antigen processing and presentation   
Protein Interaction DatabaseCTSB
Wikipedia pathwaysCTSB
Gene fusion - rearrangments
Polymorphisms : SNP, mutations, diseases
SNP Single Nucleotide Polymorphism (NCBI)CTSB
snp3D : Map Gene to Disease1508
Genetic variants : HAPMAPCTSB
Exome VariantCTSB
ICGC programENSG00000164733 
Somatic Mutations in Cancer : COSMICCTSB 
CONAN: Copy Number AnalysisCTSB 
Mutations and Diseases : HGMDCTSB
Genomic VariantsCTSB  CTSB [DGVbeta]
Pred. of missensesPolyPhen-2  SIFT(SG)  SIFT(JCVI)  Align-GVGD  MutAssessor  Mutanalyser  
Pred. splicesGeneSplicer  Human Splicing Finder  MaxEntScan  
Disease Genetic AssociationCTSB
Huge Navigator CTSB [HugePedia]  CTSB [HugeCancerGEM]
General knowledge
Homologs : HomoloGeneCTSB
Homology/Alignments : Family Browser (UCSC)CTSB
Phylogenetic Trees/Animal Genes : TreeFamCTSB
Chemical/Protein Interactions : CTD1508
Chemical/Pharm GKB GenePA27027
Clinical trialCTSB
Cancer Resource (Charite)ENSG00000164733
Other databases
PubMed236 Pubmed reference(s) in Entrez


E-64 [L-trans-epoxysuccinyl-leucyl-amido(4-guanidino)butane] and related epoxides as inhibitors of cysteine proteinases.
Barrett AJ, Kembhavi AA, Hanada K.
Acta Biol Med Ger. 1981;40(10-11):1513-7.
PMID 7044005
Confirmation of the human cathepsin B gene (CTSB) assignment to chromosome 8.
Fong D, Chan MM, Hsieh WT, Menninger JC, Ward DC.
Hum Genet. 1992 Apr;89(1):10-2.
PMID 1577456
Characterization of the cathepsin B gene and multiple mRNAs in human tissues: evidence for alternative splicing of cathepsin B pre-mRNA.
Gong Q, Chan SJ, Bajkowski AS, Steiner DF, Frankfater A.
DNA Cell Biol. 1993 May;12(4):299-309.
PMID 8494608
Identification of two new exons and multiple transcription start points in the 5'-untranslated region of the human cathepsin-B-encoding gene.
Berquin IM, Cao L, Fong D, Sloane BF.
Gene. 1995 Jul 4;159(2):143-9.
PMID 7622042
Crystal structures of human procathepsin B at 3.2 and 3.3 Angstroms resolution reveal an interaction motif between a papain-like cysteine protease and its propeptide.
Turk D, Podobnik M, Kuhelj R, Dolinar M, Turk V.
FEBS Lett. 1996 Apr 22;384(3):211-4.
PMID 8617355
Cathepsin B and cysteine proteinase inhibitors in human lung cancer cell lines.
Heidtmann HH, Salge U, Abrahamson M, Bencina M, Kastelic L, Kopitar-Jerala N, Turk V, Lah TT.
Clin Exp Metastasis. 1997 Jul;15(4):368-81.
PMID 9219725
Equistatin, a new inhibitor of cysteine proteinases from Actinia equina, is structurally related to thyroglobulin type-1 domain.
Lenarcic B, Ritonja A, Strukelj B, Turk B, Turk V.
J Biol Chem. 1997 May 23;272(21):13899-903.
PMID 9153250
Cystatin inhibition of cathepsin B requires dislocation of the proteinase occluding loop. Demonstration By release of loop anchoring through mutation of his110.
Pavlova A, Krupa JC, Mort JS, Abrahamson M, Bjork I.
FEBS Lett. 2000 Dec 29;487(2):156-60.
PMID 11150500
Cathepsin B-like cysteine proteases confer intestinal cysteine protease activity in Haemonchus contortus.
Shompole S, Jasmer DP.
J Biol Chem. 2001 Jan 26;276(4):2928-34.
PMID 11032834
Comparison of potential biological markers cathepsin B, cathepsin L, stefin A and stefin B with urokinase and plasminogen activator inhibitor-1 and clinicopathological data of breast carcinoma patients.
Levicar N, Kos J, Blejec A, Golouh R, Vrhovec I, Frkovic-Grazio S, Lah TT.
Cancer Detect Prev. 2002;26(1):42-9.
PMID 12088202
The alternative use of exons 2 and 3 in cathepsin B mRNA controls enzyme trafficking and triggers nuclear fragmentation in human cells.
Muntener K, Zwicky R, Csucs G, Baici A.
Histochem Cell Biol. 2003 Feb;119(2):93-101.
PMID 12610728
Cathepsin B and its role(s) in cancer progression.
Podgorski I, Sloane BF.
Biochem Soc Symp. 2003;(70):263-76.
PMID 14587299
Intracellular and extracellular cathepsin B facilitate invasion of MCF-10A neoT cells through reconstituted extracellular matrix in vitro.
Premzl A, Zavasnik-Bergant V, Turk V, Kos J.
Exp Cell Res. 2003 Feb 15;283(2):206-14.
PMID 12581740
Molecular regulation of human cathepsin B: implication in pathologies.
Yan S, Sloane BF.
Biol Chem. 2003 Jun;384(6):845-54.
PMID 12887051
Carboxypeptidases cathepsins X and B display distinct protein profile in human cells and tissues.
Kos J, Sekirnik A, Premzl A, Zavasnik Bergant V, Langerholc T, Turk B, Werle B, Golouh R, Repnik U, Jeras M, Turk V.
Exp Cell Res. 2005 May 15;306(1):103-13.
PMID 15878337
Proteolytic-antiproteolytic balance and its regulation in carcinogenesis.
Skrzydlewska E, Sulkowska M, Koda M, Sulkowski S.
World J Gastroenterol. 2005 Mar 7;11(9):1251-66.
PMID 15761961
Unique neuronal functions of cathepsin L and cathepsin B in secretory vesicles: biosynthesis of peptides in neurotransmission and neurodegenerative disease.
Hook VY.
Biol Chem. 2006 Oct-Nov;387(10-11):1429-39.
PMID 17081116
Cathepsin cysteine proteases in cardiovascular disease.
Lutgens SP, Cleutjens KB, Daemen MJ, Heeneman S.
FASEB J. 2007 Oct;21(12):3029-41.
PMID 17522380
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Written04-2008Zala Jevnikar, Janko Kos
Faculty of Pharmacy, University of Ljubljana, Ljubljana, Slovenia


This paper should be referenced as such :
Jevnikar, Z ; Kos, J
CTSB (cathepsin B)
Atlas Genet Cytogenet Oncol Haematol. 2009;13(2):126-129.
Free online version   Free pdf version   [Bibliographic record ]

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indexed on : Fri Jul 11 16:57:52 CEST 2014

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