Trp53, the mouse ortholog of the human TP53 tumor suppressor gene, is crucial in maintaining cellular homeostasis. It plays extensive roles as the "guardian of the genome," regulating the cell cycle, DNA repair, apoptosis, cellular metabolism, and senescence, thus balancing cell death and proliferation [3]. Mutations or deletions of TP53 lead to loss of p53 activity, a common occurrence in the majority of sporadic cancers [3].

In Trp53 -deficient mouse models, different phenotypes have been observed. BALB/c-Trp53 -deficient mice showed a delayed involution phenotype and a mammary tumor phenotype, enhancing understanding of p53's role in involution, hormonal regulation of its activity, and cooperation with other oncogenic pathways in mammary tumorigenesis [2]. The co-ablation of Rb1 and Trp53 in the mouse adrenal medulla using a Cre/loxP system led to the development of bilateral pheochromocytomas, indicating Trp53 is an efficient genetic modifier of Rb1 loss in pheochromocytoma development [4]. In the Trp53+/- mouse model, which has been used in short-term carcinogenicity testing, positive responses to genotoxic carcinogens were observed, often with an increase in spontaneously occurring tumors [1].

In conclusion, Trp53 is a key tumor suppressor gene, regulating multiple cellular processes. Mouse models, especially gene-knockout models, have significantly contributed to understanding its role in diseases such as breast cancer, pheochromocytoma, and in carcinogenicity testing, providing insights into the mechanisms of tumorigenesis and potential therapeutic strategies.

References:

1. Floyd, Eugenia, Mann, Peter, Long, Gerald, Ochoa, Ricardo. . The Trp53 hemizygous mouse in pharmaceutical development: points to consider for pathologists. In Toxicologic pathology, 30, 147-56. doi:. https://pubmed.ncbi.nlm.nih.gov/11890468/

2. Blackburn, Anneke C, Jerry, D Joseph. 2002. Knockout and transgenic mice of Trp53: what have we learned about p53 in breast cancer? In Breast cancer research : BCR, 4, 101-11. doi:. https://pubmed.ncbi.nlm.nih.gov/12052252/

3. Merino, Diana, Malkin, David. . p53 and hereditary cancer. In Sub-cellular biochemistry, 85, 1-16. doi:10.1007/978-94-017-9211-0_1. https://pubmed.ncbi.nlm.nih.gov/25201186/

4. Tonks, Ian D, Mould, Arne W, Schroder, Wayne A, Walker, Graeme J, Kay, Graham F. . Dual loss of rb1 and Trp53 in the adrenal medulla leads to spontaneous pheochromocytoma. In Neoplasia (New York, N.Y.), 12, 235-43. doi:. https://pubmed.ncbi.nlm.nih.gov/20234817/