PI3 Gene (Peptidase Inhibitor 3)
PI3: A key regulator of inflammation and tissue repair through inhibition of neutrophil elastase
Gene Information Card
| Symbol | PI3 |
|---|---|
| Full Name | Peptidase Inhibitor 3 |
| Gene Type | protein-coding |
| Chromosomal Location | 20q13.12 |
| NCBI Gene ID | 5266 ncbi.nlm.nih.gov/gene/5266 |
| Ensembl ID | ENSG00000124102 |
| UniProt ID | P19957 |
| OMIM ID | 182130 |
| HGNC ID | 8947 |
| Aliases | ESPI, SKALP, WAP3, elafin |
Description
PI3 (Peptidase Inhibitor 3), also known as elafin or SKALP, encodes a serine protease inhibitor that specifically targets neutrophil elastase and proteinase 3. It is involved in the regulation of inflammation, tissue remodeling, and antimicrobial defense. The protein is secreted by epithelial cells and is upregulated in response to inflammatory stimuli. PI3 has been implicated in various diseases, including chronic obstructive pulmonary disease (COPD), psoriasis, and certain cancers.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Chronic Obstructive Pulmonary Disease (COPD) | Elafin deficiency leads to unchecked neutrophil elastase activity, contributing to lung tissue destruction and inflammation. | ClinVar, NCBI Gene |
| Psoriasis | Overexpression of PI3 in psoriatic skin lesions suggests a role in abnormal keratinocyte proliferation and inflammation. | NCBI Gene, UniProt |
| Cystic Fibrosis | Reduced elafin levels in airway secretions correlate with increased neutrophil elastase activity and disease severity. | ClinVar, PubMed |
| Non-Small Cell Lung Cancer | PI3 expression is altered in lung tumors, potentially affecting tumor progression and immune evasion. | COSMIC, NCBI Gene |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Lung | 12.5 | Medium |
| Skin | 8.3 | Medium |
| Esophagus | 6.1 | Low |
| Trachea | 5.4 | Low |
| Salivary Gland | 4.2 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| A549 (Lung carcinoma) | 15.2 | High expression |
| HaCaT (Keratinocyte) | 10.8 | Moderate expression |
| HEK 293 (Embryonic kidney) | 2.1 | Low expression |
| HeLa (Cervical carcinoma) | 1.5 | Very low expression |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1A>G | Missense | <0.01% | Unknown functional effect |
| c.124G>A | Missense | <0.01% | Reported in ClinVar as benign |
| c.205C>T | Nonsense | <0.01% | Predicted loss of function |
Mutation functional classification
Loss of Function (LOF)
Nonsense mutations (e.g., c.205C>T) are predicted to cause premature truncation and loss of protease inhibitory activity.
Gain of Function (GOF)
No gain-of-function mutations have been reported for PI3.
Dominant Negative (DN)
No dominant-negative mutations have been described for PI3.
View complete mutation data：
Gene Ontology (GO)
Pathways
• Neutrophil degranulation (Reactome: R-HSA-6798695)
• Innate immune system (Reactome: R-HSA-168249)
Protein Summary
The PI3 protein, elafin (also known as SKALP), is a 95-amino-acid secreted serine protease inhibitor belonging to the WAP (whey acidic protein) family. It specifically inhibits neutrophil elastase and proteinase 3, protecting tissues from proteolytic damage during inflammation. Elafin is produced by epithelial cells and is upregulated in response to cytokines such as TNF-α and IL-1β. Its structure includes a four-disulfide core domain typical of WAP proteins. Elafin also exhibits antimicrobial properties and is involved in wound healing and tissue remodeling.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| PI3 Knockout HEK293 Cell Line | EDJ-KQ2398 | Human | 5266 | Details Get a Quote |
| PI3 Knockout A-549 Cell Line | EDJ-KQ22888 | Human | 5266 | Details Get a Quote |
| PI3 Knockout HeLa Cell Line | EDJ-KQ22889 | Human | 5266 | Details Get a Quote |
| PI3 Knockout HCT 116 Cell Line | EDJ-KQ71096 | Human | 5266 | Details Get a Quote |
