Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.30.2 (endonuclease)
18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Neoplasms arising from glial cells make up the most common group of primary brain tumors. The clinical outcome, especially the survival rates of the patients with brain tumours depend on tumour grade expressing its malignancy. A prognosis for glioblastomas (WHO IV) is very poor, but for astrocytomas (WHO I and II) it is relatively favourable. For oligodendrogliomas a longer survival time than for glioblastomas is observed. There is evidence that oxidative stress and reactive oxygen species (ROS) are crucial in the etiology and progression of a number of human diseases, including neoplasms. An oxidative damage of DNA, lipids and proteins is caused mainly with hydroxyl radical (*OH), the most reactive ROS species and may be seriously deleterious. In addition to all four basic nucleotides: adenosine (A), guanosine (G), tymidine (T) and cytosine (C), 5-methylcytosine (m5C) is a rare but normal component of cellular DNA and occurs mainly within a sequence of a structural gene or in regulatory regions. In the reaction with hydroxyl radical all DNA components can be modified, but m5C is relatively easily deaminated to thymine, which, in turn, pairs with adenine and after a round of replication, CG to TA transition occurs. Because thymine is a normal DNA base, therefore the product of spontaneous deamination of m5C is not so easily detected by cell's DNA repair system. Thus, 5-methylcytosine residue constitutes a mutational hotspot and DNA methylation pattern in patients might be useful as a primary diagnostic tool or as a marker for early detection of relapse of the disease. In recent years a new mechanism of posttranscriptional gene silencing has been discovered and named RNA interference (RNAi). This phenomenon is based on mRNA degradation mediated by small double-stranded RNA molecules, approximately 19-28 nucleotides in length, called short interfering RNAs (siRNAs). These molecules are produced from long dsRNAs by a dsRNA-specific endonuclease (DICER) and form 300 kD multi-enzyme complex (RISC) which by Watson-Crick base-pairing of noncoding strand with their mRNA-targets induce specific degradation. The high sequence-specificity of RNAi makes it a new, promising tool in a gene-function analysis as well as in potential therapeutics development.
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PMID:The diagnosis and therapy of brain tumours. 1624 17

MicroRNAs (miRNAs) are 20-24 nucleotide endogenous regulatory molecules conserved in higher eukaryotes. In Arabidopsis, miRNAs are produced through step-wise cleavages of primary miRNA precursors (pri-miRNAs) by DICER-LIKE1 (DCL1). This cleavage step is also supported by a double-stranded RNA-binding protein, HYPONASTIC LEAVES1 (HYL1). In many cases, mature miRNA is predominantly incorporated into an endonuclease, ARGONAUTE1 (AGO1), which degrades miRNA-targeted mRNAs. Here, we examined and revealed whole genome transcriptomes in ago1-25 and hyl1-2 mutants using tiling arrays. The data in this paper are valuable for understanding the relationship between the miRNA pathway and its effect on transcriptomes.
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PMID:Transcriptome analyses revealed diverse expression changes in ago1 and hyl1 Arabidopsis mutants. 1963 21

In plant cells, DICER-LIKE4 processes perfectly double-stranded RNA (dsRNA) into short interfering (si) RNAs, and DICER-LIKE1 generates micro (mi) RNAs from primary miRNA transcripts (pri-miRNA) that form fold-back structures of imperfectly dsRNA. Both si and miRNAs direct the endogenous endonuclease, ARGONAUTE1 to cleave complementary target single-stranded RNAs and either small RNA (sRNA)-directed pathway can be harnessed to silence genes in plants. A routine way of inducing and directing RNA silencing by siRNAs is to express self-complementary single-stranded hairpin RNA (hpRNA), in which the duplexed region has the same sequence as part of the target gene's mRNA. Artificial miRNA (amiRNA)-mediated silencing uses an endogenous pri-miRNA, in which the original miRNA/miRNA* sequence has been replaced with a sequence complementary to the new target gene. In this chapter, we describe the plasmid vector systems routinely used by our research group for the generation of either hpRNA-derived siRNAs or amiRNAs.
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PMID:Vectors and methods for hairpin RNA and artificial microRNA-mediated gene silencing in plants. 2118 31

The aim of this study was to identify the candidate causal single nucleotide polymorphisms (SNPs) and candidate causal mechanisms that contribute to bone mineral density (BMD) and to generate a SNP to gene to pathway hypothesis using an analytical pathway-based approach. We used hip BMD GWAS data of the genotypes of 301,019 SNPs in 5,715 Europeans. ICSNPathway (identify candidate causal SNPs and pathways) analysis was applied to the BMD GWAS dataset. The first stage involved the pre-selection of candidate causal SNPs by linkage disequilibrium analysis and the functional SNP annotation of the most significant SNPs found. The second stage involved the annotation of biological mechanisms for the pre-selected candidate causal SNPs using improved-gene set enrichment analysis. ICSNPathway analysis identified seven candidate SNPs, eight candidate pathways, and seven hypothetical biological mechanisms. Eight pathways are as follows; gamma-hexachlorocyclohexane degradation (nominal p-value < 0.001, false discovery rate (FDR) <0.001), regulation of the smoothened signaling pathway (nominal p-value < 0.001, FDR = 0.016), TACI and BCMA stimulation of B cell immune response (nominal p-value < 0.001, FDR = 0.021), endonuclease activity (nominal p-value = 0.001, FDR = 0,026), regulation of defense response to virus (nominal p-value = 0.001, FDR = 0.028), serine_type_endopeptidase_inhibitor_activity (nominal p-value = 0.001, FDR = 0.044), endoribonuclease activity (nominal p-value = 0.002, FDR = 0.045), and myeloid leukocyte differentiation (nominal p-value = 0.001, FDR = 0.050). The most significant causal pathway was gamma-hexachlorocyclohexane degradation. CYP3A5, PON2, PON3, CMBL, PON1, ALPL, CYP3A43, CYP3A7, ACP6, ACPP, and ALPI (p < 0.05) are involved in the pathway of gamma-hexachlorocyclohexane degradation. Further examination of the gene contents revealed that DBR1, DICER1, EXO1, FEN1, POP1, POP4, RPP30, and RPP38 were involved in 2 of the 8 pathways (p < 0.05). By applying ICSNPathway analysis to BMD GWAS data, we identified seven candidate SNPs and eight pathways involving gamma-hexachlorocyclohexane degradation, which may contribute to low BMD.
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PMID:Pathway analysis of genome-wide association study for bone mineral density. 2253 38

MicroRNAs (miRNAs) are a class of endogenous, non-coding RNAs that mediate post-transcriptional gene silencing by inhibiting mRNA translation and promoting mRNA decay. DICER1, an RNase III endonuclease encoded by Dicer1, is required for processing short 21-22 nucleotide miRNAs from longer double-stranded RNA precursors. Here, we investigate the loss of Dicer1 in mouse postnatal male germ cells to determine how disruptions in the miRNA biogenesis pathway may contribute to infertility. Reduced levels of Dicer1 transcripts and DICER1 were confirmed in germ cell knock-out (GCKO) testes by postnatal day 18 (P18). Compared to wild-type (WT) at 8 weeks, GCKO males had no change in body weight; yet showed significant reductions in testis mass and sperm number. Histology and fertility tests confirmed spermatogenic failure in GCKO males. Array analyses at P18 showed that in comparison to WT testes, 75% of miRNA genes and 37% of protein coding genes were differentially expressed in GCKO testes. Among these, 96% of miRNA genes were significantly down-regulated, while 4% miRNA genes were overexpressed. Interestingly, we observed preferential overexpression of genes encoded on the sex chromosomes in GCKO testes, including more than 80% of previously identified targets of meiotic sex chromosome inactivation (MSCI). Compared to WT, GCKO mice showed higher percentages of germ cells at early meiotic stages (leptotene and zygotene) but lower percentages at later stages (pachytene, diplotene and metaphase I) providing evidence that deletion of Dicer1 leads to disruptions in meiotic progression. Therefore, deleting Dicer1 in early postnatal germ cells resulted in deregulation of transcripts encoded by genes on the sex chromosomes, impaired meiotic progression and led to spermatogenic failure and infertility.
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PMID:Deregulated sex chromosome gene expression with male germ cell-specific loss of Dicer1. 2305 86

MicroRNAs (miRNAs) are small RNAs that control gene expression through silencing of target mRNAs. Mature miRNAs are processed from primary miRNA transcripts by the endonuclease activity of the DICER-LIKE1 (DCL1) protein complex. Mechanisms exist that allow the DCL1 complex to precisely excise the miRNA from its precursor. Our understanding of miRNA biogenesis, particularly its intersection with transcription and other aspects of RNA metabolism such as splicing, is still evolving. Mature miRNAs are incorporated into an ARGONAUTE (AGO) effector complex competent for target gene silencing but are also subjected to turnover through a degradation mechanism that is beginning to be understood. The mechanisms of miRNA target silencing in plants are no longer limited to AGO-catalyzed slicing, and the contribution of translational inhibition is increasingly appreciated. Here, we review the mechanisms underlying the biogenesis, turnover, and activities of plant miRNAs.
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PMID:Biogenesis, turnover, and mode of action of plant microRNAs. 2389 25

Despite the fact that alveolar macrophages play an important role in smoking-related disease, little is known about what regulates their pathophysiologic phenotype. Evaluating smoker macrophages, we found significant down-regulation of multiple microRNAs (miRNAs). This work investigates the hypothesis that cigarette smoke alters mature miRNA expression in lung macrophages by inhibiting processing of primary miRNA transcripts. Studies on smoker alveolar macrophages showed a defect in miRNA maturation. Studies on the miRNA biogenesis machinery led us to focus on the cytosolic RNA endonuclease, DICER. DICER cleaves the stem-loop structure from pre-miRNAs, allowing them to dissociate into their mature 20-22-nucleotide single-stranded form. DICER activity assays confirmed impaired DICER activity following cigarette smoke exposure. Further protein studies demonstrated a decreased expression of the native 217-kDa form of DICER and an accumulation of high molecular weight forms with cigarette smoke exposure. This molecular mass shift was shown to contain SUMO moieties and could be blocked by silencing RNA directed at the primary SUMOylating ligase, Ubc9. In determining the cigarette smoke components responsible for changes in DICER, we found that N-acetylcysteine, an antioxidant and anti-aldehyde, protected DICER protein and activity from cigarette smoke extract. This massive down-regulation of miRNAs (driven in part by alterations in DICER) may be an important regulator of the disease-promoting macrophage phenotype found in the lungs of smokers.
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PMID:A microRNA processing defect in smokers' macrophages is linked to SUMOylation of the endonuclease DICER. 2466 3

The endonuclease DICER that processes micro-RNAs and small interfering RNAs is essential for normal spermatogenesis and male fertility. We previously showed that the deletion of Dicer1 gene in postnatal spermatogonia in mice using Ngn3 promoter-driven Cre expression caused severe defects in the morphogenesis of haploid spermatid to mature spermatozoon, including problems in cell polarization and nuclear elongation. In this study, we further analyzed the same mouse model and revealed that absence of functional DICER in differentiating male germ cells induces disorganization of the cell-cell junctions in the seminiferous epithelium. We detected discontinuous and irregular apical ectoplasmic specializations between elongating spermatids and Sertoli cells. The defective anchoring of spermatids to Sertoli cells caused a premature release of spermatids into the lumen. Our findings may help also explain the abnormal elongation process of remaining spermatids because these junctions and the correct positioning of germ cells in the epithelium are critically important for the progression of spermiogenesis. Interestingly, cell adhesion-related genes were generally upregulated in Dicer1 knockout germ cells. Claudin 5 ( Cldn5 ) was among the most upregulated genes and we show that the polarized localization of CLAUDIN5 in the apical ectoplasmic specializations was lost in Dicer1 knockout spermatids. Our results suggest that DICER-dependent pathways control the formation and organization of cell-cell junctions in the seminiferous epithelium via the regulation of cell adhesion-related genes.
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PMID:DICER Regulates the Formation and Maintenance of Cell-Cell Junctions in the Mouse Seminiferous Epithelium. 2651 Aug 68

DICER1, a RNAse endonuclease involved in the processing of siRNA and microRNA, is known to play a pivotal role in the post-transcriptional regulation of gene expression. Germ line mutations in the DICER1 gene increase the risk for different types of tumors. At present, DICER1 syndrome is an established, though not well defined, member of the group of genetic tumor predisposition syndromes. Here, we report a DICER1 syndrome family with a medical history of different rare tumors mostly occurring at a young age. The tumor spectrum in this family included both DICER1 syndrome-typical forms, such as pleuropulmonary blastoma, multinodular goiter, and cystic nephroma, and not previously reported manifestations, such as pilomatrixoma, and juvenile basal cell carcinoma. The latter tumor types are usually considered to be indicators of familial adenomatous polyposis and basal cell nevus syndrome.
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PMID:DICER1 syndrome can mimic different genetic tumor predispositions. 2657 41

The RNAse III endonuclease DICER is a key regulator of microRNA (miRNA) biogenesis and is frequently decreased in a variety of malignancies. We characterized the role of DICER in glioblastoma (GB), specifically demonstrating its effects on the ability of glioma stem-like cells (GSCs) to form tumors in a mouse model of GB. DICER silencing in GSCs reduced their stem cell characteristics, while tumors arising from these cells were more aggressive, larger in volume, and displayed a higher proliferation index and lineage differentiation. The resulting tumors, however, were more sensitive to radiation treatment. Our results demonstrate that DICER silencing enhances the tumorigenic potential of GSCs, providing a platform for analysis of specific relevant miRNAs and development of potentially novel therapies against GB.
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PMID:DICER governs characteristics of glioma stem cells and the resulting tumors in xenograft mouse models of glioblastoma. 2742 Nov 40


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