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A. Saadi, D.T. Vuong, M.R. Al–Ubaidi; Developmental Expression of rb and p53 and Related Genes in the Normal Retina . Invest. Ophthalmol. Vis. Sci. 2006;47(13):3128.
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Retinal cells achieve postmitosis early during the postnatal development. Therefore, it is reasonable to assume that P53 and/or pRb are involved in maintaining the postmitotic state. In this study we investigated the pattern of expression of p53 and rb genes, their family members and their regulators during development of the normal retina.
Quantitative RT PCR was used to determine the steady state levels of target transcripts in retinal RNA extracts from different developmental time points. Samples analyzed were between embryonic day 15 (E15) and postnatal day 30 (P30). Western blotting and immunoprecipitation were used to determine regulation of target gene products.
Transcripts for p63, p73, E2F2, E2F6, and E2F7 were found to be absent in developing and mature retinas. However, transcripts for p53, rb, p107, p130, mdm2, mdm4, p21, PCNA, tert, yy1, E2F1b, E2F3, E2F4, and E2F5 were detected at E15; increased before birth and gradually decreased as the retina achieved postmitosis at P11. Those transcripts were maintained at that steady state level for the life of the retina. At the protein level, western blot analysis confirmed the same pattern of expression for pRb, mdm2, YY1, and E2F1, while P53 could not be detected by western blot.
Downregulation of the studied genes seems to be a requirement for the retinal cells to enter the postmitosis state. This means that although some of these genes may play a role in retinal development, they play minimal if any role in adult retinal function.
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