Project description:Imprinted genes with parental-biased allelic expression are enriched in pathways regulating energy homeostasis. Here, we functionally characterize a large cluster of maternally-expressed microRNAs (miRNAs) to explore the molecular and cellular consequences of imprinted miRNA activity in neurons. Using an induced neuron (iN) culture system, we show maternally-expressed miRNAs from the miR-379/410 cluster direct the RNA induced silencing complex (RISC) to transcriptional and developmental regulators, including paternally-expressed transcripts. Maternal deletion of this imprinted miRNA cluster results in increased protein levels of several targets and up-regulation of a broader gene program regulating synaptic transmission and neuronal function. A subset of these transcriptional changes can be attributed to de-repression of Plagl1, a paternally-expressed transcriptional activator that regulates Igf2, a major factor in energy homeostasis. These data suggest non-coding RNAs actively engage as maternally-expressed miRNAs antagonize paternally-driven gene programs in neurons.
Project description:Imprinted genes with parental-biased allelic expression are frequently co-regulated and enriched in common biological pathways. Here, we functionally characterize a large cluster of microRNAs (miRNAs) expressed from the maternally inherited allele ("maternally expressed") to explore the molecular and cellular consequences of imprinted miRNA activity. Using an induced neuron (iN) culture system, we show that maternally expressed miRNAs from the miR-379/410 cluster direct the RNA-induced silencing complex (RISC) to transcriptional and developmental regulators, including paternally expressed transcripts like Plagl1. Maternal deletion of this imprinted miRNA cluster resulted in increased protein levels of several targets and upregulation of a broader transcriptional program regulating synaptic transmission and neuronal function. A subset of the transcriptional changes resulting from miR-379/410 deletion can be attributed to de-repression of Plagl1. These data suggest maternally expressed miRNAs antagonize paternally driven gene programs in neurons.
Project description:Genetic imprinting is an epigenetic phenomenon that describes unequal expression of paternal and maternal alleles of a gene in sexually reproducing organisms including mammals and flowering plants. The function of imprinted genes was rarely reported. We report genome-wide analysis of gene expression, DNA methylation, and small RNAs in the rice endosperm and functional tests of five imprinted genes in seed development using CRISPR/Cas9 editing technology. We identified 162 maternally expressed genes(MEGs) and 95 paternally expressed genes (PEGs) in the rice endosperm, which were associated with miniature inverted-repeat transposable elements, imprinted differentially methylated loci, and some 21-22-siRNAs and lncRNAs. Remarkably, one-third of MEGs and nearly half of PEGs were associated with grain-yield quantitative trait loci and enriched in the endosperm-expressed genes. Disrupting two MEGs increased the amount of small starch granules and reduced grain size, weight, and embryo size, while mutating three PEGs reduced starch content and seed fertility. Our data support both MEGs and PEGs in rice are required for starch and nutrient accumulation, mediating offspring fitness and optimal seed size. This imprinting strategy provides potential means for improving grain yield of rice and other cereal crops.
Project description:MicroRNAs (miRNAs) are a recently discovered class of noncoding genes that regulate the translation of target mRNA. More than 300 miRNAs have now been discovered in humans, although the function of most is still unknown. A highly sensitive, semiquantitative real-time polymerase chain reaction method was used to reveal the differential expression of several miRNAs during the development of both mouse and human lung. Of note was the up-regulation in neonatal mouse and fetal human lung of a maternally imprinted miRNA cluster located at human chromosome 14q32.31 (mouse chromosome 12F2), which includes the miR-154 and miR-335 families and is situated within the Gtl2-Dio3 domain. Conversely, several miRNAs were up-regulated in adult compared with neonatal/fetal lung, including miR-29a and miR-29b. Differences in the spatial expression patterns of miR-154, miR-29a, and miR-26a was demonstrated using in situ hybridization of mouse neonatal and adult tissue using miRNA-specific locked nucleic acid (LNA) probes. Of interest, miR-154 appeared to be localized to the stroma of fetal but not adult lungs. The overall expression profile was similar for mouse and human tissue, suggesting evolutionary conservation of miRNA expression during lung development and demonstrating the importance of maternally imprinted miRNAs in the developmental process.
Project description:The mammalian imprinted Dlk1-Dio3 domain contains multiple lncRNAs, mRNAs, the largest miRNA cluster in the genome and four differentially methylated regions (DMRs), and deletion of maternal RNA within this locus results in embryonic lethality, but the mechanism by which this occurs is not clear. Here, we optimized the model of maternally expressed RNAs transcription termination in the domain and found that the cause of embryonic death was apoptosis in the embryo, particularly in the liver. We generated a mouse model of maternally expressed RNAs silencing in the Dlk1-Dio3 domain by inserting a 3×polyA termination sequence in Gtl2 locus. By analyzing mouse embryos RNA-Seq data combined with histological analysis, we found that silence of maternally expressed RNAs in the domain activated apoptosis, causing vascular rupture of fetal liver, resulting hemorrhage and injury. Mechanistically, termination of Gtl2 transcription results in the silencing of the maternally expressed RNAs and activation of the paternally expressed genes in the interval, and it is the gene itself rather than the IG-DMR and Gtl2-DMR that causes the above phenotypes. In conclusion, these findings illuminate a novel mechanism by which silencing of the maternally expressed RNAs within Dlk1-Dio3 domain leads to hepatic hemorrhage and embryonic death through activation of the apoptosis.
Project description:Some flowering plant and vertebrate genes are expressed primarily or exclusively from either the maternal or paternal allele, a phenomenon called genomic imprinting. Flowering plant imprinted gene expression has been described primarily in endosperm, a terminal nutritive tissue consumed by the embryo during seed development or after germination. Imprinted expression in Arabidopsis thaliana endosperm is orchestrated by differences in cytosine DNA methylation between the paternal and maternal genomes, as well as by Polycomb group (PcG) proteins. Currently only eleven imprinted Arabidopsis genes are known. Here we use extensive sequencing of cDNA libraries to identify many new paternally and maternally imprinted genes in A. thaliana endosperm, including transcription factors, proteins involved in hormone signaling, and epigenetic regulators. The imprinted status of many maternally-expressed genes is not altered by mutations in the DNA-demethylating glycosylase DEMETER, the DNA methyltransferase MET1 or the core PcG protein FIE, indicating that these genes are regulated by novel mechanisms or deposited from maternal tissues. We did not find any imprinted genes in the embryo. Our results demonstrate that imprinted gene expression, particularly from the maternal genome, is an extensive, mechanistically complex phenomenon that likely affects multiple aspects of seed development. Epigenetics Examination of genomic imprinting in Arabidopsis endosperm
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. MiRNA expression and modification profile during early embryo development of fruit fly and zebra fish using high throughput sequencing