Adenylation of maternally inherited microRNAs by Wispy
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ABSTRACT: Early development depends heavily on accurate control of maternally inherited mRNAs, and yet it remains unknown how maternal microRNAs (miRNAs) are regulated during maternal to zygotic transition (MZT). We here find that maternal miRNAs are highly adenylated at their 3' ends in mature oocytes and early embryos. Pervasive adenylation is observed in oocytes of fly, sea urchin and mouse, indicating that maternal miRNA adenylation may be widely conserved in animals. We identify Wispy as the enzyme responsible for miRNA adenylation in flies. Wispy is known to be expressed specifically in oocytes and early embryos and function as a noncanonical poly(A) polymerase. Knockout of wispy abrogates miRNA adenylation and induces miRNA accumulation in fly eggs whereas overexpression of Wispy increases adenylation and reduces miRNA levels in S2 cells. Adenylation occurs on both the 5p and 3p miRNAs, indicating that Wispy acts on miRNAs after Dicer processing. We further find that Wispy interacts with Ago1 through protein-protein interaction, which may allow the effective and selective adenylation of miRNAs. Thus, adenylation may contribute to the clearance of maternally deposited miRNAs during MZT. Our work provides the first mechanistic insights into the regulation of maternal miRNAs and illustrates the importance of RNA tailing in development. MiRNA expression and modification profile during early embryo development of fruit fly and zebra fish using high throughput sequencing
Project description:Early development depends heavily on accurate control of maternally inherited mRNAs, and yet it remains unknown how maternal microRNAs (miRNAs) are regulated during maternal to zygotic transition (MZT). We here find that maternal miRNAs are highly adenylated at their 3' ends in mature oocytes and early embryos. Pervasive adenylation is observed in oocytes of fly, sea urchin and mouse, indicating that maternal miRNA adenylation may be widely conserved in animals. We identify Wispy as the enzyme responsible for miRNA adenylation in flies. Wispy is known to be expressed specifically in oocytes and early embryos and function as a noncanonical poly(A) polymerase. Knockout of wispy abrogates miRNA adenylation and induces miRNA accumulation in fly eggs whereas overexpression of Wispy increases adenylation and reduces miRNA levels in S2 cells. Adenylation occurs on both the 5p and 3p miRNAs, indicating that Wispy acts on miRNAs after Dicer processing. We further find that Wispy interacts with Ago1 through protein-protein interaction, which may allow the effective and selective adenylation of miRNAs. Thus, adenylation may contribute to the clearance of maternally deposited miRNAs during MZT. Our work provides the first mechanistic insights into the regulation of maternal miRNAs and illustrates the importance of RNA tailing in development.
Project description:During microRNA-biogenesis, stem-loop structured precursors are processed in two endonucleolytic steps, giving rise to mature microRNAs (miRNAs). This process is not only regulated at the level of transcription but also posttranscriptionally by RNA-binding proteins (RBPs). Here we have used a proteomics-based pull-down approach to map and characterize the interactome of 72 pre-miRNAs in eleven cell lines. We identify over 150 RBPs that interact specifically with distinct pre-miRNAs. To demonstrate their functional relevance, we used RNAi knockdown and CRISPR/Cas-mediated knockout experiments and analyzed changes in miRNA levels. Indeed, a large number of the investigated candidates have effects on miRNA-processing under our experimental conditions, including several C3H-zinc-finger proteins. Ultimately, we show that TRIM71/Lin41 is a potent regulator of miR-29a processing and its inactivation directly affects miR-29a targets. In summary, we provide an extended database of RBPs that interact with pre-miRNAs in different cell types helping to elucidate posttranscriptional regulation of miRNA biogenesis on a global scale.
Project description:The precise control of microRNA (miRNA) biogenesis is important for various cellular functions, and its dysregulation is often associated with human diseases. We previously reported that Terminal uridylyl transferase 4 (TUT4) down-regulates let-7 miRNA biogenesis by oligo-uridylating let-7 precursor (pre-let-7) in mouse embryonic stem cells and that a pluripotency marker Lin28 promotes a processivity of TUT4. Here we find that TUT4 positively controls let-7 biogenesis by adding a uridine residue to the 3’ end of pre-let-7 in the absence of Lin28. Such mono-uridylation enhances Dicer processing by generating an optimal end structure of pre-let-7 for Dicer recognition and may protect pre-miRNA from trimming. Moreover, TUT7, TUT4 and TUT2 redundantly regulate pre-let-7 processing and simultaneous knock down of these TUTs leads to the decrease of mature let-7 and the accumulation of pre-let-7 in cells. This study provides a novel regulation mechanism of miRNA biogenesis, which may function in development and tumorigenesis. HeLa cells were transfected with siRNA two times over a 4~5 day period.
Project description:MicroRNAs (miRNAs) have been shown to have important functions in a variety of cellular processes. Here we report on miRNA expression and their dynamic regulation during mouse oogenesis and early embryos. We show that following specific deletion of Dicer from growing oocytes, the mutant oocytes cease development and were unable to progress through the first cell division. While the mutant mature oocytes seemed morphologically normal, they had disorganized spindle. Using detailed single cell cDNA microarray analysis of normal versus mutant oocytes, we found that a large proportion of maternal genes, including C-mos, are under the control of miRNAs. This study provides strong evidence that maternal miRNAs are essential for the earliest stages of mouse embryonic development. mRNA expression was compared with miRNA expression in dicer knockout and wild-type mouse mature oocyte.
Project description:MicroRNAs (miRNAs) have been shown to have important functions in a variety of cellular processes. Here we report on miRNA expression and their dynamic regulation during mouse oogenesis and early embryos. We show that following specific deletion of Dicer from growing oocytes, the mutant oocytes cease development and were unable to progress through the first cell division. While the mutant mature oocytes seemed morphologically normal, they had disorganized spindle. Using detailed single cell cDNA microarray analysis of normal versus mutant oocytes, we found that a large proportion of maternal genes, including C-mos, are under the control of miRNAs. This study provides strong evidence that maternal miRNAs are essential for the earliest stages of mouse embryonic development. Keywords: mRNA and miRNA expression comparison
Project description:Eukaryotic mRNAs are subject to multiple types of tailing which critically influence mRNA stability and translatability. To investigate RNA tails at the genomic scale, we previously developed TAIL-seq, but its low sensitivity precluded its application to biological materials of minute quantity. In this study, we report a new version of TAILseq (mRNA TAIL-seq or mTAIL-seq) with enhanced sequencing depth for mRNAs (by ~1000 fold compared to the previous version). The improved method allows us to investigate the regulation of poly(A) tail in Drosophila oocytes and embryos. We find that maternal mRNAs are polyadenylated mainly during late oogenesis, prior to fertilization, and that further modulation occurs upon egg activation. Wispy, a noncanonical poly(A) polymerase, adenylates the vast majority of maternal mRNAs with a few intriguing exceptions such as ribosomal protein transcripts. By comparing mTAILseq data with ribosome profiling data, we find a strong coupling between poly(A) tail length and translational efficiency during egg activation. Our data suggest that regulation of poly(A) tail in oocytes shapes the translatomic landscape of embryos, thereby directing the onset of animal development. By virtue of the high sensitivity, low cost, technical robustness, and broad accessibility, mTAIL-seq will be a potent tool to improve our understanding of mRNA tailing in diverse biological systems. Ten separate sets of TAIL-seq experiments were performed. Two sets of HeLa cells are untransfected normal cells. Eight sets of fly sample include a pair of wild type and mutant.
Project description:Dicer, which is required for the processing of both microRNAs (miRNAs) and small interfering RNAs (siRNAs), is essential for oocyte maturation. Oocytes express both miRNAs and endogenous siRNAs (endo-siRNAs). To determine whether the abnormalities in Dicer knockout oocytes during meiotic maturation are secondary to the loss of endo-siRNAs and/or miRNAs, we deleted Dgcr8, which encodes a RNA binding protein specifically required for miRNA processing. In striking contrast to Dicer, Dgcr8 deficient oocytes matured normally and, when fertilized with wild-type sperm, produced healthy appearing offspring, even though miRNA levels were reduced to similar levels as Dicer deficient oocytes. Furthermore, the deletion of both maternal and zygotic Dgcr8 alleles did not impair preimplantation development including the determination of the inner cell mass (ICM) and trophectoderm. Most surprisingly, the mRNA profiles of wild-type and Dgcr8 null oocytes were essentially identical while Dicer null oocytes showed hundreds of misregulated transcripts. These findings show that miRNA function is globally suppressed during oocyte maturation and preimplantation development and that endo-siRNAs, rather than miRNAs, underlie the Dicer knockout phenotype in oocytes. We used microarrays to understand at the global level how loss of miRNAs and/or siRNAs is impacting mRNA levels in mouse oocytes.
Project description:As the fetal heart develops, cardiomyocyte proliferation potential decreases while fatty acid oxidative capacity increases, a highly regulated transition known as cardiac maturation. Small noncoding RNAs, such as microRNAs (miRNAs), contribute to the establishment and control of tissue-specific transcriptional programs. However, small RNA expression dynamics and genome wide miRNA regulatory networks controlling maturation of the human fetal heart remain poorly understood. Transcriptome profiling of small RNAs revealed the temporal expression patterns of miRNA, piRNA, circRNA, snoRNA, snRNA and tRNA in the developing human heart between 8 and 19 weeks of gestation. Our analysis revealed that miRNAs were the most dynamically expressed small RNA species throughout mid-gestation. Cross-referencing differentially expressed miRNAs and mRNAs predicted 6,200 mRNA targets, 2134 of which were upregulated and 4066 downregulated as gestation progresses. Moreover, we found that downregulated targets of upregulated miRNAs predominantly control cell cycle progression, while upregulated targets of downregulated miRNAs are linked to energy sensing and oxidative metabolism. Furthermore, integration of miRNA and mRNA profiles with proteomes and reporter metabolites revealed that proteins encoded in mRNA targets, and their associated metabolites, mediate fatty acid oxidation and are enriched as the heart develops.This study revealed the small RNAome of the maturing human fetal heart. Furthermore, our findings suggest that coordinated activation and repression of miRNA expression throughout mid-gestation is essential to establish a dynamic miRNA-mRNA-protein network that decreases cardiomyocyte proliferation potential while increasing the oxidative capacity of the maturing human fetal heart.
Project description:Poor maternal nutrition causes intrauterine growth restriction (IUGR); however, its effects on fetal cardiac development are unclear. We have developed a baboon model of moderate maternal undernutrition, leading to IUGR. We hypothesized that the IUGR affects fetal cardiac structure and metabolism. Six control pregnant baboons ate ad-libitum (CTRL)) or 70% CTRL from 0.16 of gestation (G). Fetuses were euthanized at C-section at 0.9G under general anesthesia. Male but not female IUGR fetuses showed left ventricular fibrosis inversely correlated with birth weight. Expression of extracellular matrix protein TSP-1 was increased (p<0.05) in male IUGR. Expression of cardiac fibrotic markers TGFß, SMAD3 and ALK-1 were downregulated in male IUGRs with no difference in females. Autophagy was present in male IUGR evidenced by upregulation of ATG7 expression and lipidation LC3B. Global miRNA expression profiling revealed 56 annotated and novel cardiac miRNAs exclusively dysregulated in female IUGR, and 38 cardiac miRNAs were exclusively dysregulated in males (p<0.05). Fifteen (CTRL) and 23 (IUGR) miRNAs, were differentially expressed between males and females (p<0.05) suggesting sexual dimorphism, which can be at least partially explained by differential expression of upstream transcription factors (e.g. HNF4a, and NF?B p50). Lipidomics analysis of fetal cardiac tissue exhibited a net increase in diacylglycerol and plasmalogens and a decrease in triglycerides and phosphatidylcholines. In summary, IUGR resulting from decreased maternal nutrition is associated with sex-dependent dysregulations in cardiac structure, miRNA expression, and lipid metabolism. If these changes persist postnatally, they may program offspring for higher later life cardiac risk.
Project description:Background: Metazoan embryos undergo a maternal-to-zygotic transition (MZT) during which a subset of maternal gene products is eliminated and the zygotic genome becomes transcriptionally active. RNA-binding proteins (RBPs) and the microRNA-induced silencing complex (miRISC) â of which Argonaute 1 (AGO1) is a key component in Drosophila â target maternal mRNAs for degradation. The Drosophila Smaug, Brain tumor (BRAT) and Pumilio (PUM) RBPs direct the degradation of maternal mRNAs. Here we elucidate Smaugâs roles in regulation of miRNAs and miRISC during the MZT. Results: By global analysis of small RNAs at several stages during the MZT, we show that the vast majority of all miRNA species encoded by the Drosophila genome (85%) are expressed during the MZT. Whereas a subset of these miRNAs is loaded into oocytes by the mother and stays at constant levels during the MZT, dozens of miRNA species are either newly synthesized or re-expressed in the early embryo. Loss of Smaug has a profound effect on miRNAs but little effect on piRNAs or siRNAs. Smaug is required for production of new miRNAs during the MZT; Smaug-bound AGO1 reflects the constellation and abundance of the miRNAs present in early embryos; and Smaug is required for the increase in AGO1 protein levels that occurs during the MZT. As a consequence of low miRISC activity in smaug mutants, maternal mRNAs that are normally targeted for degradation by zygotic miRNAs fail to be cleared. BRAT and PUM share target mRNAs with miRISC during the MZT while the miR-309 miRNA family coregulates targets of BRAT but not PUM. Conclusions: Smaug controls the MZT through direct targeting of a subset of maternal mRNAs for degradation and, indirectly, through production and function of miRNAs and miRISC, which control clearance of a distinct subset of maternal mRNAs. BRAT and/or PUM function together with miRISC during the latter process. With respect to miRISC-dependent transcript degradation, Smaug is required (1) for the synthesis of miRNAs, (2) for synthesis and stabilization of AGO1, and (3) for action of AGO1 in association with its bound miRNAs. In smaug mutants a large number of maternal mRNAs persist and the MZT fails. Examination of miRNA expresssion at different time points in wild type and smuag mutant early embryos .