Tumor suppressor gene p53 prevents carcinoma by?
Ans. is 'd' i.e., All of the above * p53 gene is located on chromosome 17 & acts as molecular policeman that prevents the propagation of genetically damage cell. p53 gene product, i.e. p53 protein is a DNA binding protein in the nucleus, when called into action, it controls the transcription of several other genes.* When there is DNA damage due to irradiation, UV light or mutagenic chemicals, there is rapid increase in p53 levels.* p53 causes :-a) Cell cycle arrest: p-53 induces transcription of p21, a CDK inhibitor. p21 inhibit cyclin DCDK- 4 complex and there is arrest of cell cycle late in G1 phase. This allow time for DNA repair.b) DNA repair: p-53 also helps in DNA repair directly by inducing transcription of GADD 45 (growth arrest and DNA damage). GADD 45 encodes a protein that is involved in DNA repair.* If DNA damage is repaired successfully, p53 activate MDM-3 and this MDM-3 induce degradation of p-53 - Relieve in cell cycle block. If DNA damage cannot be successfully repaired, p53 induces apoptosis by inducing the activation of apoptosis inducing gene BAX. So p-53 prevents replication of cell with defective DNA - p53 functions as a critical gatekeeper against formation of cancer. Mutation in p53 leads to carcinogenesis because of loss of above protective mechanism.
DNA repair
Cell cycle arrest
Apoptosis induction
All of the above
Neoplasia