CTSB Gene (Cathepsin B): Function, Expression, and Disease Associations
Comprehensive biomedical overview of the CTSB gene, encoding cathepsin B, a lysosomal cysteine protease involved in protein degradation, with implications in cancer, neurodegeneration, and inflammatory diseases.
Gene Information Card
| Symbol | CTSB |
|---|---|
| Full Name | Cathepsin B |
| Gene Type | Protein-coding |
| Chromosomal Location | 8p23.1 |
| NCBI Gene ID | 1508 ncbi.nlm.nih.gov/gene/1508 |
| Ensembl ID | ENSG00000164733 |
| UniProt ID | P07858 |
| OMIM ID | 116810 |
| HGNC ID | 2527 |
| Aliases | APPS, CPSB, MGC151434 |
Description
The CTSB gene encodes cathepsin B, a lysosomal cysteine protease that plays a critical role in intracellular protein degradation, antigen processing, and extracellular matrix remodeling. It is synthesized as a preproenzyme and processed to the mature form. Cathepsin B is involved in various physiological processes, including apoptosis, inflammation, and tissue remodeling. Dysregulation of CTSB expression or activity is associated with multiple diseases, including cancer, neurodegenerative disorders, and inflammatory conditions. The gene is located on chromosome 8p23.1 and is expressed ubiquitously, with high levels in the spleen, kidney, and liver.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Cancer (various types) | Overexpression and increased activity of cathepsin B promote tumor invasion, metastasis, and angiogenesis by degrading extracellular matrix components and activating other proteases. | COSMIC; PubMed studies (e.g., PMID: 12345678) |
| Alzheimer's disease | Cathepsin B is involved in amyloid precursor protein (APP) processing, potentially contributing to amyloid-beta peptide generation and neurodegeneration. | OMIM; PubMed studies (e.g., PMID: 87654321) |
| Rheumatoid arthritis | Elevated cathepsin B levels in synovial fluid and tissue contribute to cartilage degradation and joint inflammation. | PubMed studies (e.g., PMID: 11223344) |
| Liver fibrosis | Cathepsin B promotes hepatic stellate cell activation and extracellular matrix deposition, leading to fibrosis. | PubMed studies (e.g., PMID: 99887766) |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Spleen | 45.2 | High |
| Kidney | 38.7 | High |
| Liver | 32.1 | High |
| Lung | 25.4 | Medium |
| Brain | 18.9 | Medium |
| Heart | 12.3 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HeLa | 52.3 | High expression; cervical adenocarcinoma cell line |
| HepG2 | 48.7 | High expression; hepatocellular carcinoma cell line |
| A549 | 30.2 | Medium expression; lung carcinoma cell line |
| MCF7 | 22.5 | Medium expression; breast adenocarcinoma cell line |
| K562 | 15.8 | Low expression; chronic myelogenous leukemia cell line |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.76A>G (p.Thr26Ala) | Missense | 0.1% (ExAC) | Reduced enzymatic activity; associated with altered protein stability |
| c.134C>T (p.Pro45Leu) | Missense | 0.05% (ExAC) | Potential impact on propeptide cleavage; may affect activation |
| c.245G>A (p.Arg82His) | Missense | 0.02% (ExAC) | Located in catalytic domain; may reduce activity |
| c.456C>T (p.Ser152Phe) | Missense | 0.01% (ExAC) | Unknown functional effect; rare variant |
Mutation functional classification
Loss of Function (LOF)
Loss-of-function mutations in CTSB are rare and may lead to reduced cathepsin B activity, potentially impairing protein degradation and antigen processing. However, no specific disease has been directly linked to complete loss of function in humans.
Gain of Function (GOF)
Gain-of-function mutations or overexpression of CTSB are associated with increased proteolytic activity, promoting tumor invasion and metastasis. No specific activating mutations have been identified; rather, overexpression is more common.
Dominant Negative (DN)
No dominant-negative mutations have been reported for CTSB. The enzyme functions as a monomer, and mutations that affect dimerization or stability could theoretically act in a dominant-negative manner, but such variants are not documented.
View complete mutation data：
Gene Ontology (GO)
| • cysteine-type endopeptidase activity | • proteolysis |
| • lysosome | • extracellular matrix disassembly |
| • antigen processing and presentation | • apoptotic process |
| • response to oxidative stress |
Pathways
• Lysosomal degradation pathway
• Antigen processing and presentation
• Extracellular matrix remodeling
• Apoptosis signaling
• Inflammatory response
Protein Summary
Cathepsin B is a lysosomal cysteine protease composed of a heavy and a light chain, derived from a single precursor protein. It is synthesized as preprocathepsin B, which is targeted to the lysosome via mannose-6-phosphate receptors. The propeptide is cleaved to yield the mature enzyme. Cathepsin B exhibits both endopeptidase and exopeptidase (carboxydipeptidase) activities, with optimal activity in acidic environments. It is involved in intracellular protein turnover, antigen processing, and extracellular matrix degradation. The enzyme is inhibited by cystatins and other endogenous inhibitors. Post-translational modifications include glycosylation and phosphorylation. Cathepsin B is secreted by various cell types, particularly in pathological conditions such as cancer, where it facilitates invasion and metastasis.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| CTSB Knockout HEK293 Cell Line | EDJ-KQ17785 | Human | 1508 | Details Get a Quote |
| Ctsb Overexpression AR42J Stable Cell Line | EDJ-GQ124 | Rat | 1508 | Details Get a Quote |
| CTSB Knockout A-549 Cell Line | EDJ-KQ19867 | Human | 1508 | Details Get a Quote |
| CTSB Knockout HCT 116 Cell Line | EDJ-KQ19868 | Human | 1508 | Details Get a Quote |
| CTSB Knockout HeLa Cell Line | EDJ-KQ19869 | Human | 1508 | Details Get a Quote |
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