Years after the discovery that Dicer is a key enzyme in gene-silencing, the role of its helicase domain remains enigmatic. Here we show that this domain is critical for accumulation of certain endogenous small interfering RNAs (endo-siRNAs) in C. elegans. The domain is required for the production of the direct products of Dicer, or primary endo-siRNAs, and consequently, affects levels of downstream intermediates, the secondary endo-siRNAs. Consistent with the role of endo-siRNAs in silencing, their loss correlates with an increase in cognate mRNA levels. We find that the helicase domain of Dicer is not required for microRNA (miRNA) processing, or RNA interference following exposure to exogenous double-stranded RNA. Comparisons of wildtype and helicase-defective strains using deep-sequencing analyses show that the helicase domain is required by a subset of annotated endo-siRNAs, in particular, those associated with the slightly longer 26 nucleotide small RNA species containing a 5' guanosine. Overall design: We reintroduced either wildtype Dicer, or Dicer harboring a mutation (K39A) in it''s helicase domain, into dcr-1(ok247) mutant worms via transgene rescue. We then used high-throughput sequencing to compare levels of small RNAs present in each of these strains.
Dicer's helicase domain is required for accumulation of some, but not all, C. elegans endogenous siRNAs.
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Transgenic mice were generated that expressed the inhibitor of apoptosis and mitotic regulator survivin in pancreatic islet beta cells. Control non-transgenic or transgenic islets were then used in a model of islet transplantation in diabetic recipient mice and tested for their ability to correct hyperglycemia and allow long-term engraftment of tranplanted islets in vivo. Control or transgenic islets were analyzed by chip microarray for potential transcriptional changes associated with transgenic expression of survivin, in vivo.
Genome-wide analysis of Polycomb targets in Drosophila melanogaster.
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Down syndrome (DS), a complex genetic disorder caused by chromosome 21 trisomy, is associated with mitochondrial dysfunction leading to the accumulation of damaged mitochondria. Here we report that mitophagy, a form of selective autophagy activated to clear damaged mitochondria is deficient in primary human fibroblasts derived from individuals with DS leading to accumulation of damaged mitochondria with consequent increases in oxidative stress. We identified two molecular bases for this mitophagy deficiency: PINK1/PARKIN impairment and abnormal suppression of macroautophagy. First, strongly downregulated PARKIN and the mitophagic adaptor protein SQSTM1/p62 delays PINK1 activation to impair mitophagy induction after mitochondrial depolarization by CCCP or antimycin A plus oligomycin. Secondly, mTOR is strongly hyper-activated, which globally suppresses macroautophagy induction and the transcriptional expression of proteins critical for autophagosome formation such as ATG7, ATG3 and FOXO1. Notably, inhibition of mTOR complex 1 (mTORC1) and complex 2 (mTORC2) using AZD8055 (AZD) restores autophagy flux, PARKIN/PINK initiation of mitophagy, and the clearance of damaged mitochondria by mitophagy. These results recommend mTORC1-mTORC2 inhibition as a promising candidate therapeutic strategy for Down Syndrome. Overall design: mRNA-Seq profiling of 9 2N and 8 DS human fibroblasts samples of age 5 months (< 1 year) and 2 years. These samples come from 5 unrelated 2N individuals (of which 2 individuals, one each of 5 months and 2 years, have 3 replicates each) and 3 unrelated DS individuals (of which 2 individuals, one each of 5 months and 2 years, have 3 replicates each). Five samples were reanalyzed from GSE55504.
mTOR hyperactivation in Down Syndrome underlies deficits in autophagy induction, autophagosome formation, and mitophagy.
Sex, Age, SubjectView Samples
Thirty to 60% of CD56dimCD16bright NK cells in healthy adults express CD57, which is not expressed on immature CD56bright NK cells or fetal and newborn NK cells. We hypothesized that CD57+ NK cells within the CD56dim mature NK cell subset are highly mature and might be terminally differentiated.
CD57 defines a functionally distinct population of mature NK cells in the human CD56dimCD16+ NK-cell subset.
Specimen part, SubjectView Samples
Endosperm is an absorptive structure that supports embryo development or seedling germination in angiosperms. The endosperm of cereals is a main source of food, feed, and industrial raw materials worldwide. However, the gene regulatory networks that control endosperm cell differentiation remain largely unclear. As a first step toward characterizing these networks, we profiled the mRNAs in five major cell types of the differentiating endosperm and in the embryo and four maternal compartments of the kernel. Comparisons of these mRNA populations revealed the diverged gene expression programs between filial and maternal compartments, and an unexpected close correlation between embryo and the aleurone layer of endosperm. Gene co-expression network analysis identified co-expression modules associated with single or multiple kernel compartments including modules for the endosperm cell types, some of which showed enrichment of previously identified temporally activated and/or imprinted genes. Detailed analyses of a co-expression module highly correlated with the basal endosperm transfer layer (BETL) identified a regulatory module activated by MRP-1, a regulator of BETL differentiation and function. These results provide a high-resolution atlas of gene activity in the compartments of the maize kernel and help to uncover the regulatory modules associated with the differentiation of the major endosperm cell types. Overall design: RNAs from ten compartments of the maize kernel including the central starchy endosperm (CSE), conducting zone (CZ), aleurone (AL), basal endosperm transfer layer (BETL), embryo-surrounding region (ESR), nucellus (NU), pericarp (PE), placenta-chalazal region (PC), the vascular region of the pedicel (PED), and the embryo (EMB) were isolated at 8 days after pollination (DAP) using laser-capture microdissection and sequenced using an Illumina HiSeq 2000 platform.
RNA sequencing of laser-capture microdissected compartments of the maize kernel identifies regulatory modules associated with endosperm cell differentiation.
Age, Specimen part, Cell line, SubjectView Samples
We examine the global effect of hBD3 on transcription in TLR4-stimulated macrophages and for the first time show that hBD3 inhibits the transcription of critical pro-inflammatory genes.
Human β-defensin 3 affects the activity of pro-inflammatory pathways associated with MyD88 and TRIF.
Specimen part, Treatment, TimeView Samples
A number of macrophage and macrophage-like cells are responsible for immune response to challenges. Despite their shared role, these immune cells differ in the inflammatory response and impact on physiology and behavior. The purpose of this study was to profile mRNA levels (transcriptome) to better understand differences between immune cells under homeostasis using two mouse strains. Overall design: total RNA samples were obtained from 12 mice per strain and immune cell type and were subjected to paired-end RNA sequencing
Microglia Transcriptome Changes in a Model of Depressive Behavior after Immune Challenge.
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The p21 RAS subfamily of small GTPases, including KRAS, HRAS, and NRAS, regulates cell proliferation, cytoskeletal organization and other signaling networks, and is the most frequent target of activating mutations in cancer. Activating germline mutations of KRAS and HRAS cause severe developmental abnormalities leading to Noonan, cardio-facial-cutaneous and Costello syndrome, but activating germline mutations of NRAS have not been reported. Autoimmune lymphoproliferative syndrome (ALPS) is the most common genetic disease of lymphocyte apoptosis and causes autoimmunity as well as excessive lymphocyte accumulation, particularly of CD4-, CD8- ab T cells. Mutations in ALPS typically affect CD95 (Fas/APO-1)-mediated apoptosis, one of the extrinsic death pathways involving tumor necrosis factor receptor (TNFR) superfamily proteins, but certain ALPS individuals have no such mutations. We show here that the salient features of ALPS as well as a predisposition to hematological malignancies can be caused by a heterozygous germline Gly13Asp activating mutation of the NRAS oncogene that does not impair CD95-mediated apoptosis. The increase in active, GTP-bound NRAS augments RAF/MEK/ERK signaling which markedly decreases the pro-apoptotic protein BIM and attenuates intrinsic, nonreceptor-mediated mitochondrial apoptosis. Thus, germline activating mutations in NRAS differ from other p21 Ras oncoproteins by causing selective immune abnormalities without general developmental defects. Our observations on the effects of NRAS activation indicate that RAS-inactivating drugs, such as farnesyl-transferase inhibitors (FTIs) should be examined in human autoimmune and lymphocyte homeostasis disorders.
NRAS mutation causes a human autoimmune lymphoproliferative syndrome.
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To better understand transcriptional regulation during human oogenesis and pre-implantation embryonic development, we defined stage-specific transcription, which revealed cleavage stage as highly distinctive. We present multiple lines of evidence that two cleavage-specific homologs, mouse mDUX and human DUX4, each activate hundreds of cleavage-specific endogenous genes (e.g. ZSCAN4, ZFP352, KDM4E) and retroviral elements (MERVL/HERVL-family). Remarkably, mDux expression converts mouse ESCs into two-cell embryo-like (2C-like) cells by binding to MERVL promoters/enhancers and restoring the chromatin landscape (via ATACseq) to the pattern of mouse two-cell embryos Overall design: We derived and analyzed transcriptomes from seven stages of developing human oocytes and embryos. The blastocyst stage embryos were dissected into inner cell mass (ICM) and trophectoderm lineages and processed independently. Cells from each stage were pooled and RNA was extracted. Two stranded libraries were prepared from each stage. Each library was then split and amplied for 12 or 14 PCR cycles, resulting in four technical replicates per developmental stage. 12 and14 cycle replicates from the same library prep were merged after sequencing
Conserved roles of mouse DUX and human DUX4 in activating cleavage-stage genes and MERVL/HERVL retrotransposons.
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