Small RNAs in early mammalian development: From gametes to gastrulation

The Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research, Center for Reproductive Sciences, and Department of Urology, University of California San Francisco, San Francisco, CA 94143, USA.
Development (Impact Factor: 6.46). 05/2011; 138(9):1653-61. DOI: 10.1242/dev.056234
Source: PubMed


Small non-coding RNAs, including microRNAs (miRNAs), endogenous small interfering RNAs (endo-siRNAs) and Piwi-interacting RNAs (piRNAs), play essential roles in mammalian development. The function and timing of expression of these three classes of small RNAs differ greatly. piRNAs are expressed and play a crucial role during male gametogenesis, whereas endo-siRNAs are essential for oocyte meiosis. By contrast, miRNAs are ubiquitously expressed in somatic tissues and function throughout post-implantation development. Surprisingly, however, miRNAs are non-essential during pre-implantation embryonic development and their function is suppressed during oocyte meiosis. Here, we review the roles of small non-coding RNAs during the early stages of mammalian development, from gamete maturation through to gastrulation.

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    • "The transcriptome of these oocytes is widely perturbed and expression of the most abundant transposable element in mouse oocytes is increased (Stein et al. 2015). It is believed that, after fertilization, neither miRNAs nor siRNAs play a role in preimplantation development, since zygotic deletions of Dgcr8, Dicer, and Ago2 do not have a phenotype until after embryo implantation (Bernstein et al. 2003; Morita et al. 2007; Suh and Blelloch 2011). Moreover, maternal deletion of Dgcr8 has no phenotype until postimplantation , suggesting no essential role for maternal miRNAs throughout oocyte maturation or during the whole preimplantation development (Suh et al. 2010). "
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    ABSTRACT: A hallmark of oocyte development in mammals is the dependence on the translation and utilization of stored RNA and proteins rather than the de novo transcription of genes in order to sustain meiotic progression and early embryo development. In the absence of transcription, the completion of meiosis and early embryo development in mammals relies significantly on maternally synthesized RNAs. Post-transcriptional control of gene expression at the translational level has emerged as an important cellular function in normal development. Therefore, the regulation of gene expression in oocytes is controlled almost exclusively at the level of mRNA and protein stabilization and protein synthesis. This current review is focused on the recently emerged findings on RNA distribution related to the temporal and spatial translational control of the meiotic progression of the mammalian oocyte.
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    • "Oocytes contain large amounts of RNA of all classes (Watanabe et al., 2006, 2008; Tam et al., 2008). Previous studies have demonstrated that maternal non-coding RNAs can be stable for several cell divisions and contribute to gene regulation in early development (Suh and Blelloch, 2011). In contrast, spermatozoa have a highly condensed nucleus, are transcriptionally nearly silent and contain little cytoplasm. "
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    • "Interestingly, it was shown that specific RNAi effectors that are capable of both destabilizing and stabilizing certain transcripts during the MZT are, in fact, essential for the MZT [30]. Because different classes of small RNAs play a key role in the MZT [31], [32], inherited small noncoding RNAs could be involved in the remodeling of RNA profiles during early embryogenesis (Figure 2). "
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