Transcriptional activity of p53 isoforms

Protein p53 kao tumor supresorima središnju ulogu u kontroli staničnog ciklusa i tumorigeneze. Nedavno je otkriveno da gen p53 kodira 9 izoformi (p53, p53 β , p53 γ , 133p53, 133p53 β , 133p53 γ , 40p53, 40p53 β i 40p53 γ ) nastalih alternativnim izrezivanjem ili prepisivanjem s alternativnog promotora u intronu 4. Ekspresija izoformi tkivno je specifična, a biološka funkcija im nije u potpunosti razjašnjena. Gen p53 ima dva srodnika velike strukturne i funkcionalne sličnosti, p63 i p73 . Spomenuti geni također imaju određen broj izoformi, koje djelovanje proteina p53 čine još složenijim. Testom luciferaze istražena je transkripcijska aktivnost izoformi p73 β , p53, p53 β , p53 γ , 133p53, 133p53 β , 133p53 γ i 40p53 transfeciranih u stanice H1299, koje nemaju eksprimiran protein p53 divljeg tipa. Dokazana je transkripcijska aktivnost svih istraživanih izoformi. Izoforme p73 β i p53 β pokazuju najveću transkripcijsku aktivnost. Izoforme p53 γ i 40p53 pokazuju značajnu razinu transkripcijske aktivnosti, dok izoforme 133p53, 133p53 β i 133p53 γ imaju izrazito nisku razinu transkripcijske aktivnosti. Metodom Western blot dokazana je ekspresija svih istraživanih izoformi na razini proteina.Protein p53 as a tumor suppressor plays a central role in the cell cycle control and tumorigenesis. It was recently discovered that the gene p53 encodes nine different protein isoforms (p53, p53β, p53γ, 133p53, 133p53β, 133p53γ, 40p53, 40p53β and 40p53γ) due to alternative splicing and usage of the alternative promoter in intron 4. The expression of isoforms is tissue-specific, and their biological function is not fully understood. p53 gene has two relatives of major structural and functional similarities, p63 and p73. They also have a number of isoforms, which make p53 activity more complex. Luciferase assay was used to detect transcriptional activity of isoforms, p73β, p53, p53β, p53γ, 133p53, 133p53β, 133p53γ and 40p53 that were trasfected into H1299 cells, which lack expression of wildtype p53 protein. Transcriptional activity of each isoform was detected. p73β and p53β isoforms show the greatest degree of ranscriptional activity, compared to full-length p53. p53γ and 40p53 show a significant level of transcriptional activity, whereas 133p53, 133p53β and 133p53γ have extremely low levels of transcription activity. Western blot method has shown the expression of all isoforms at the protein level analysis