TP63

Tumor protein p63 also known as transformation-related protein 63 is a is_associated_with::protein that in humans is encoded by the TP63 is_associated_with::gene.

TP63 also known as the p63 gene was discovered 20 years after the discovery of the is_associated_with::p53 tumor suppressor gene and along with is_associated_with::p73 constitutes the p53 gene family based on their structural similarity. Despite being discovered significantly later than p53, phylogenetic analysis of p53, p63 and p73, suggest that p63 was the original member of the family from which p53 and p73 evolved.

Function
Tumor protein p63 is a member of the p53 family of is_associated_with::transcription factors. p63 -/- mice have several developmental defects which include the lack of limbs and other tissues, such as teeth and mammary glands, which develop as a result of interactions between is_associated_with::mesenchyme and is_associated_with::epithelium. TP63 encodes for two main isoforms by alternative promoters (TAp63 and ΔNp63). ΔNp63 is involved in multiple functions during skin development and in adult stem/progenitor cell regulation. In contrast, TAp63 has been mostly restricted to its apoptotic function and more recently as the guardian of oocyte integrity. Recently, two new functions have been attributed to TAp63 in heart development and premature aging.

Clinical significance
TP63 mutations underlie several malformation syndromes that include cleft lip and/or palate as a hallmark feature. Mutations in the TP63 gene are associated with is_associated_with::ectrodactyly-ectodermal dysplasia-cleft syndrome in which a midline cleft lip is a common feature, is_associated_with::cleft lip/palate syndrome 3 (EEC3); is_associated_with::ectrodactyly (also known as split-hand/foot malformation 4 (SHFM4)); ankyloblepharon-ectodermal dysplasia-cleft lip/palate (AEC) or is_associated_with::Hay–Wells syndrome in which a midline cleft lip is also a common feature, is_associated_with::Acro–dermato–ungual–lacrimal–tooth syndrome (ADULT); is_associated_with::limb-mammary syndrome; is_associated_with::Rap-Hodgkin syndrome (RHS); and is_associated_with::orofacial cleft 8. Both cleft lip with or without a cleft palate and cleft palate only features have been seen to segregate within the same family with a TP63 mutation. Recently, induced pluripotent stem cells have be produced from patients affected by EEC syndromes by cell reprogramming. The defective epithelial commitment could be partially rescued by a small therapeutic compound.

Diagnostic utility
p63 is_associated_with::immunostaining has utility for head and neck squamous cell carcinomas, differentiating prostatic is_associated_with::adenocarcinoma (the most common type of is_associated_with::prostate cancer) and benign prostatic tissue; normal prostatic glands stain with p63 (as they have basal cells), while the is_associated_with::malignant glands in prostatic adenocarcinoma (which lacks these cells) do not. P63 is also helpful in distinguishing poorly differentiated squamous cell carcinoma from small cell carcinoma or adenocarcinoma. P63 should be strongly stained in poorly differentiated squamous cell, but negative in small cell or adenocarcinoma.

Interactions
TP63 has been shown to interact with is_associated_with::HNRPAB. It also activates IRF6 transcription through the IRF6 enhancer element.

Regulation
There is some evidence that the expression of p63 is regulated by the microRNA miR-203.