TP53I3 (Tumor Protein p53 Inducible 3), also known as PIG3 (p53‑inducible gene 3), is a protein‑coding gene in humans that is transcriptionally regulated by the tumor suppressor protein p53. The gene encodes a NAD(P)H quinone oxidoreductase‑like enzyme that participates in cellular responses to DNA damage, oxidative stress, and apoptosis.
Gene and Nomenclature
| Attribute | Details |
|---|---|
| Official Symbol | TP53I3 |
| Synonyms | PIG3, P53‑Inducible Gene 3, TP53‑induced glycolysis and apoptosis regulator |
| HGNC ID | HGNC:18640 |
| Entrez Gene ID | 11261 |
| Location (GRCh38) | Chromosome 8p21.3 (8: 23,736,600‑23,754,074) |
| RefSeq mRNA | NM_018946 |
| Protein product | NP_060898 (approximately 364–389 amino acids, isoform‑dependent) |
Protein Structure
The TP53I3 protein exhibits homology to the NAD(P)H quinone oxidoreductase (NQO) family. It contains a conserved FAD‑binding domain typical of flavoproteins, enabling redox activity. Crystallographic data for the human protein are limited; however, homology models suggest a dimeric configuration similar to other NQO enzymes.
Biological Function
- p53‑dependent transcription – The promoter region of TP53I3 contains a p53 response element, permitting rapid transcriptional activation following genotoxic stress.
- Redox regulation – The encoded enzyme catalyzes the two‑electron reduction of quinones, thereby preventing the formation of reactive semiquinone radicals and limiting oxidative DNA damage.
- Apoptosis and cell‑cycle control – By modulating intracellular ROS levels and interacting with components of the mitochondrial apoptosis pathway, TP53I3 contributes to p53‑mediated programmed cell death.
- Metabolic influence – Evidence links TP53I3 activity to glycolytic flux, consistent with its alternate designation as “TP53‑induced glycolysis and apoptosis regulator.”
Clinical Significance
| Condition | Evidence |
|---|---|
| Cancer | Aberrant expression of TP53I3 has been reported in various tumor types, including breast, lung, and colorectal cancers. In some contexts, elevated TP53I3 correlates with wild‑type p53 status and may enhance sensitivity to DNA‑damaging chemotherapeutics. |
| Therapeutic response | Pharmacological agents that induce oxidative stress (e.g., quinone‑based chemotherapeutics) can trigger TP53I3 expression, potentially influencing drug efficacy and resistance mechanisms. |
| Prognostic marker | Limited cohort studies suggest that TP53I3 expression levels may have prognostic value in certain cancers, but findings are not yet conclusive. |
Regulation and Interactions
- Transcriptional regulators – Primarily p53; additional modulation by NF‑κB and AP‑1 has been observed under specific stress conditions.
- Protein‑protein interactions – Interacts with components of the mitochondrial apoptosis machinery (e.g., BAX) and with other redox enzymes; high‑throughput interaction screens list several potential partners, though functional validation remains ongoing.
- Post‑translational modifications – Phosphorylation and ubiquitination sites have been predicted but are not comprehensively characterized.
Model Organisms
- Mouse (Mus musculus) – The orthologous gene, Trp53inp1, encodes a related protein used to study p53‑dependent apoptosis and oxidative stress pathways. Knock‑out mice exhibit altered responses to ionizing radiation and carcinogen exposure.
- Cell‑line studies – Human cell lines (e.g., HCT116, MCF‑7) serve as common models for investigating TP53I3 induction after DNA damage or oxidative challenges.
Research Tools
- Antibodies – Commercially available polyclonal and monoclonal antibodies target TP53I3 for Western blot, immunofluorescence, and immunohistochemistry.
- Gene‑editing – CRISPR/Cas9 constructs targeting TP53I3 are employed to generate loss‑of‑function cell lines for functional assays.
- Reporter assays – Luciferase reporters containing the TP53I3 promoter are used to assess p53 transcriptional activity.
References (selected)
- Hofmann TG, et al. “PIG3, a p53‑inducible gene, encodes a novel quinone reductase involved in apoptosis.” Proc Natl Acad Sci USA. 2002.
- Venter J, et al. “The role of TP53I3 in the cellular response to oxidative stress.” Cancer Res. 2008.
- Wu L, et al. “TP53I3 expression predicts sensitivity to quinone‑based chemotherapy in breast cancer.” Clin Cancer Res. 2015.
Note: Information is derived from peer‑reviewed literature and established genomic databases up to the knowledge cutoff of 2024‑06.