Small RNAs in early mammalian development: from gametes to gastrulation
ABSTRACT 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.
- SourceAvailable from: Frank Leigh Lu[Show abstract] [Hide abstract]
ABSTRACT: Human embryonic stem cells (hESCs) are functionally unique for their self-renewal ability and pluripotency, but the molecular mechanisms giving rise to these properties are not fully understood. hESCs can differentiate into embryoid bodies (EBs) containing ectoderm, mesoderm, and endoderm. In the miR-200 family, miR-200c was especially enriched in undifferentiated hESCs and significantly downregulated in EBs. The knockdown of the miR-200c in hESCs downregulated Nanog expression, upregulated GATA binding protein 4 (GATA4) expression, and induced hESC apoptosis. The knockdown of GATA4 rescued hESC apoptosis induced by downregulation of miR-200c. miR-200c directly targeted the 3'-untranslated region of GATA4. Interestingly, the downregulation of GATA4 significantly inhibited EB formation in hESCs. Overexpression of miR-200c inhibited EB formation and repressed the expression of ectoderm, endoderm, and mesoderm markers, which could partially be rescued by ectopic expression of GATA4. Fibroblast growth factor (FGF) and activin A/nodal can sustain hESC renewal in the absence of feeder layer. Inhibition of transforming growth factor-β (TGF-β)/activin A/nodal signaling by SB431542 treatment downregulated the expression of miR-200c. Overexpression of miR-200c partially rescued the expression of Nanog/phospho-Smad2 that was downregulated by SB431542 treatment. Our observations have uncovered novel functions of miR-200c and GATA4 in regulating hESC renewal and differentiation.Stem Cell Research 12/2013; 12(2):338-353. DOI:10.1016/j.scr.2013.11.009 · 3.91 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: MicroRNAs (miRNAs) finely tune messenger RNA (mRNA) expression. As the brain is a highly heterogeneous tissue, physiologically relevant miRNA expression profiling greatly benefits from sampling brain regions or nuclei. MiRNA expression profiling from individual samples is also important for investigating potential differences between animals according to their physiological and pathophysiological status. We have punched the arcuate (ARC) and paraventricular (PVN) nuclei from the hypothalamus of seven male Wistar rats and used them to establish a novel method for the characterization of the miRNA expression profile of individual rat brain nuclei. The identity of the ARC and PVN samples was checked for proopiomelanocortin and arginine vasopressin mRNA expression, respectively. Individual cDNA libraries were constructed from purified RNAs between 16 and 26 bases, using barcoded adapters. Libraries were multiplexed and sequenced using Illumina technology to a read depth >10(5). The ARC and PVN profiles displayed similar expression from a set of more than 210 miRNA genes. Expression was high or moderate for about twenty miRNAs that may be used to define a common ARC/PVN prototype profile of male Wistar rats. These miRNAs included seven of the eight genes of the let-7 family, the two miR-7 genes, miR-9 gene and 5' copy of the three miR-30 loci. Our method shows that the ARC and PVN from a single rat are accessible for miRNA digital characterization. This method will allow miRNA transcriptome characterization for any rat brain substructure or nuclei that can be microdissected.Journal of neuroscience methods 06/2012; 209(1):134-43. DOI:10.1016/j.jneumeth.2012.05.033 · 1.96 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Long non-coding RNAs (ncRNAs) have been shown to regulate important biological processes that support normal cellular functions. Aberrant regulation of these essential functions can promote tumor development. In this review, we underscore the importance of the regulatory role played by this distinct class of ncRNAs in cancer-associated pathways that govern mechanisms such as cell growth, invasion, and metastasis. We also highlight the possibility of using these unique RNAs as diagnostic and prognostic biomarkers in malignancies.Frontiers in Genetics 02/2012; 3:17. DOI:10.3389/fgene.2012.00017