CSTA Gene (Cystatin A)
A cysteine protease inhibitor involved in skin barrier function and tumor suppression
Gene Information Card
| Symbol | CSTA |
|---|---|
| Full Name | Cystatin A |
| Gene Type | Protein coding |
| Chromosomal Location | 3q21.1 |
| NCBI Gene ID | 1475 ncbi.nlm.nih.gov/gene/1475 |
| Ensembl ID | ENSG00000121594 |
| UniProt ID | P01040 |
| OMIM ID | 184600 |
| HGNC ID | 2481 |
| Aliases | STF1, STFA, cystatin AS |
Description
CSTA encodes cystatin A (stefin A), a member of the cystatin superfamily of cysteine protease inhibitors. It functions as a tight-binding inhibitor of cathepsins B, H, L, and S, playing a critical role in epidermal differentiation, skin barrier integrity, and regulation of proteolysis. Loss-of-function mutations cause exfoliative ichthyosis, and altered expression is implicated in various cancers.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Exfoliative ichthyosis (OMIM 607936) | Biallelic loss-of-function mutations in CSTA disrupt cystatin A activity, leading to impaired desmosome turnover and skin peeling. | ClinVar, OMIM |
| Epidermolytic ichthyosis (rare) | Missense mutations affecting protein stability and inhibitor function. | ClinVar |
| Cancer (various) | Downregulation of CSTA in several carcinomas (e.g., breast, lung) correlates with increased cathepsin activity and tumor progression. | COSMIC, NCBI |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Skin | 146.8 | High |
| Esophagus | 42.3 | Medium |
| Oral mucosa | 38.1 | Medium |
| Lung | 5.2 | Low |
| Breast | 3.1 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HaCaT (keratinocyte) | 152.0 | High expression in keratinocytes |
| A431 (epidermoid carcinoma) | 98.5 | Moderate expression |
| MCF7 (breast cancer) | 2.3 | Low expression |
| A549 (lung cancer) | 1.8 | Low expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.2T>C (p.Met1?) | Missense | Rare | Loss of start codon, loss of function |
| c.58C>T (p.Arg20*) | Nonsense | Rare | Premature stop, loss of function |
| c.143G>A (p.Gly48Glu) | Missense | Rare | Impaired inhibitor activity |
| c.247C>T (p.Arg83Cys) | Missense | Rare | Reduced stability |
Mutation functional classification
Loss of Function (LOF)
Biallelic loss-of-function mutations (nonsense, frameshift, start-loss) cause exfoliative ichthyosis due to absent cystatin A activity.
Gain of Function (GOF)
No gain-of-function mutations reported.
Dominant Negative (DN)
Not described; disease inheritance is autosomal recessive.
View complete mutation data：
Gene Ontology (GO)
Pathways
• Cysteine protease inhibition (cathepsins B
• H
• L
• S)
• Epidermal differentiation and cornification
Protein Summary
Cystatin A (stefin A) is a 98-amino-acid, 11 kDa intracellular cysteine protease inhibitor. It is highly expressed in the upper layers of the epidermis and in other stratified squamous epithelia. The protein forms a tight complex with target cathepsins, regulating proteolysis during desquamation and barrier maintenance. Its loss leads to excessive desmosome degradation and skin peeling.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| CSTA Knockout HEK293 Cell Line | EDJ-KQ4375 | Human | 1475 | Details Get a Quote |
| CSTA Knockout A-549 Cell Line | EDJ-KQ26885 | Human | 1475 | Details Get a Quote |
| CSTA Knockout HCT 116 Cell Line | EDJ-KQ26886 | Human | 1475 | Details Get a Quote |
| CSTA Knockout HeLa Cell Line | EDJ-KQ53019 | Human | 1475 | Details Get a Quote |
