Abstract：Processing bodies (P-bodies) are distinct foci within the cytoplasm of the eukaryotic cell consisting of many enzymes involved in mRNA turnover. P-bodies have been observed in somatic cells originating from vertebrates and invertebrates, plants and yeast. To date, P-bodies have been demonstrated to play fundamental roles in general mRNA decay, nonsense-mediated mRNA decay, adenylate-uridylate-rich element mediated mRNA decay, and microRNA induced mRNA silencing. Not all mRNAs which enter P-bodies are degraded, as it has been demonstrated that some mRNAs can exit P-bodies and re-initiate translation mRNAs are temporarily stored in stress granules. Stress granule is a similar granule of P-body. Stress granules are dense aggregations in the cytosol composed of proteins & RNAs that appear when the cell is under stress. The purpose of stress granules might be to protect RNAs from harmful conditions. Both P-bodies and stress granules play an important role in Post-transcriptional gene regulation. Fully grown mouse (Mus musculus) oocytes in Graafian follicles are transcriptionally silent during the period before the resumption of meiosis until after fertilization when most of the transcriptional reactivation occurs at the 2-cell stage. Products of the oocyte genome support oocyte growth and development before silencing and are also stored for use during the silent period to support oocyte maturation and the early stages of preimplantation embryo development. However, the maturation of oocytes needs a lot of proteins which are mainly generated from the translation of maternally stored mRNA. During the maturation of oocytes, different gene transcriptions expressed at specific time and precise regulation are vital. Oscillatory degradation and resynthesis of cyclins drive the somatic cell through its cycle, and the oocyte utilizes these same processes to control levels of cyclin B1 throughout the period of prophase I arrest. In the fully grown GV oocyte that contains high cyclin B1 levels, ubiquitin-mediated proteasomal degradation of cyclin B1 becomes key to regulating CDK1 activity and is essential during the subsequent stages of meiosis I and II. Known for its role as the driver of anaphase progression in mitosis, the anaphase-promoting complex (APC) is a multimeric E3 ubiquitin ligase, responsible for the ubiquitylation of cyclin B1 and other substrates, which thereby targets them for degradation by the 26S proteasome. The activity and substrate specificity of the APC are regulated by its binding to one of two coactivator proteins that function in a reciprocal manner to coordinate the different phases of the cell cycle. In somatic cells, there are two ways to regulate one gene expression, namely transcriptional regulation and post-transcriptional regulation. The cooperation of both two regulations ensure an orderly life activities in cells. On the contrary, transcriptional regulation does not exist during the maturation of oocytes. Post-transcription regulation is the only way to regulate one gene. Here, we review P-bodies and their function, discuss the function of maternal P-bodies in mouse oocyte maturation, come up with new models about how mRNAs are stored in maternal P-bodies and how mRNAs released from these granules, put forward that oocytes are novel model for the research of post-transcriptional regulation.
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