EP300

EP300 (E1A binding protein p300) is a gene that provides instructions for making a protein called p300. This protein regulates the activity of many genes in tissues throughout the body. It plays an essential role in regulating cell growth and division, prompting cells to mature and assume specialized functions (differentiate), and preventing the growth of cancerous tumors. The p300 protein appears to be critical for normal development before and after birth.

The p300 protein carries out its function by activating transcription, the process of making a blueprint of a gene for protein production. Specifically, p300 connects transcription factors, which are proteins that start the transcription process, with the complex of proteins that carries out transcription in the cell's nucleus. On the basis of this function, p300 is called a transcriptional coactivator.

The EP300 gene is located on the long (q) arm of the human chromosome 22 at position 13.2, from base pair 39,812,289 to base pair 39,900,044.

EP300 is closely related to another gene, CREBBP, which is found on human chromosome 16.

Related diseases
Mutations in the EP300 gene are responsible for a small percentage of cases of Rubinstein-Taybi syndrome. These mutations result in the loss of one copy of the gene in each cell, which reduces the amount of p300 protein by half. Some mutations lead to the production of a very short, nonfunctional version of the p300 protein, while others prevent one copy of the gene from making any protein at all. Although researchers do not know how a reduction in the amount of p300 protein leads to the specific features of Rubinstein-Taybi syndrome, it is clear that the loss of one copy of the EP300 gene disrupts normal development.

Rarely, chromosomal rearrangements involving chromosome 22 have been associated with certain types of cancer. These rearrangements, called translocations, disrupt the region of chromosome 22 that contains the EP300 gene. For example, researchers have found a translocation between chromosomes 8 and 22 in several people with a cancer of blood cells called acute myeloid leukemia (AML). Another translocation, involving chromosomes 11 and 22, has been found in a small number of people who have undergone cancer treatment. This chromosomal change is associated with the development of AML following chemotherapy for other forms of cancer.

Mutations in the EP300 gene have been identified in several other types of cancer. These mutations are somatic, which means they are acquired during a person's lifetime and are present only in certain cells. Somatic mutations in the EP300 gene have been found in a small number of solid tumors, including cancers of the colon and rectum, stomach, breast and pancreas. Studies suggest that EP300 mutations may also play a role in the development of some prostate cancers, and could help predict whether these tumors will increase in size or spread to other parts of the body. In cancer cells, EP300 mutations prevent the gene from producing any functional protein. Without p300, cells cannot effectively restrain growth and division, which can allow cancerous tumors to form.