Essay On Ribosome Biogenesis

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I. Introduction
A hallmark of proliferating cells is increased protein synthesis. Increased protein synthesis allows cells to grow before they divide. In order to increase the amount of protein synthesis, proliferating cells increase their rate of ribosome biogenesis. In other words, increased ribosome biogenesis is a hallmark of proliferating cells. Alterations in ribosome biogenesis is known to be a crucial factor in determining whether a cell will proliferate by the role alterations in ribosome biogenesis plays in p53-dependent and independent cell cycle arrest at the G1-S restriction point; ribosome biogenesis is a major factor controlling cell cycle or G1-S progression. (Giulio D, 2012)
In cells with active p53, p53 acts as a gate-keeper that monitors the ribosome biogenesis status of the cell and decides whether that cell will progress through the G1-S restriction point, that is, progress from the G1 phase to the S phase. (Giulio, D, 2012) In a scenario in which p53 decides not to allow a cell to proliferate, a cell will go through p53-mediated apoptosis.
A large percent of cancers with active p53 have been noted to have defects in the p53-mediated apoptotic pathway or the degradation of p53 by p53 degradation pathways has been noted. Another large percent of cancers exist in which there is mutated, non-active p53. The overexpression of ARF or the interruption of the MDM2:p53 interaction are a couple of therapeutic strategies for alleviating p53 degradation in cancer cells with active p53. Other chemotherapies exist that seek to correct the defect in the p53-mediated apoptotic pathway in the cancer cells with active p53. One strategy of therapy for cancer cells lacking active p53/containing mutated p53, is t...

... middle of paper ... of NPM1 are possible reasons why NPM1 also influences cell growth and transformation during tumor development. (Lindstrom, 2010) NPM1 Also interacts with HEXIMI, which regulates RNA Polymerase II transcription. (Lindstrom, 2010)
Acetylated NPM1 as well as acetylated histones disrupts nucleosomes leading to transcriptional activation. (Lindstrom, 2010) Acetylated NPM1 is preferentially found in the nucleosomes in association with RNA Polymerase II. (Lindstrom, 2010) The increase in acetylated NPM1 is noted in cancer. (Lindstrom, 2010) Finding ways to de-acetylate NPM1 is cancer cells is a possible therapeutic strategy. (Lindstrom, 2010) During mitosis NPM1 binds GCN5 inhibits its acetylation of free and mono-nucelated histones. (Lindstrom, 2010)
NPM1 also acts as a corepressor or coactivator of several transcription factors. (Lindstrom, 2010)
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