|
Mir155 Gene
MiR-155 is a microRNA that in humans is encoded by the ''MIR155'' host gene or ''MIR155HG''. MiR-155 plays a role in various physiological and pathological processes. Exogenous molecular control ''in vivo'' of miR-155 expression may inhibit malignant growth, viral infections, and enhance the progression of cardiovascular diseases. Discovery The ''MIR155HG'' was initially identified as a gene that was transcriptionally activated by promoter insertion at a common retroviral integration site in B-cell lymphomas and was formerly called BIC (B-cell Integration Cluster). The ''MIR155HG'' is transcribed by RNA polymerase II and the resulting ~1,500 nucleotide RNA is capped and polyadenylated. The 23 nucleotide single-stranded miR-155, which is harbored in exon 3, is subsequently processed from the parent RNA molecule. Biogenesis The MIR155HG RNA transcript does not contain a long open reading frame (ORF), however, it does include an imperfectly base-paired stem loop that is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MicroRNA
Micro ribonucleic acid (microRNA, miRNA, μRNA) are small, single-stranded, non-coding RNA molecules containing 21–23 nucleotides. Found in plants, animals, and even some viruses, miRNAs are involved in RNA silencing and post-transcriptional regulation of gene expression. miRNAs base-pair to complementary sequences in messenger RNA (mRNA) molecules, then silence said mRNA molecules by one or more of the following processes: * Cleaving the mRNA strand into two pieces. * Destabilizing the mRNA by shortening its poly(A) tail. * Reducing translation of the mRNA into proteins. In cells of humans and other animals, miRNAs primarily act by destabilizing the mRNA. miRNAs resemble the small interfering RNAs (siRNAs) of the RNA interference (RNAi) pathway, except miRNAs derive from regions of RNA transcripts that fold back on themselves to form short stem-loops (hairpins), whereas siRNAs derive from longer regions of double-stranded RNA. The human genome may encode ov ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mir155 Gene
MiR-155 is a microRNA that in humans is encoded by the ''MIR155'' host gene or ''MIR155HG''. MiR-155 plays a role in various physiological and pathological processes. Exogenous molecular control ''in vivo'' of miR-155 expression may inhibit malignant growth, viral infections, and enhance the progression of cardiovascular diseases. Discovery The ''MIR155HG'' was initially identified as a gene that was transcriptionally activated by promoter insertion at a common retroviral integration site in B-cell lymphomas and was formerly called BIC (B-cell Integration Cluster). The ''MIR155HG'' is transcribed by RNA polymerase II and the resulting ~1,500 nucleotide RNA is capped and polyadenylated. The 23 nucleotide single-stranded miR-155, which is harbored in exon 3, is subsequently processed from the parent RNA molecule. Biogenesis The MIR155HG RNA transcript does not contain a long open reading frame (ORF), however, it does include an imperfectly base-paired stem loop that is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RNA-induced Silencing Complex
The RNA-induced silencing complex, or RISC, is a multiprotein complex, specifically a ribonucleoprotein, which functions in gene silencing via a variety of pathways at the transcriptional and translational levels. Using single-stranded RNA (ssRNA) fragments, such as microRNA (miRNA), or double-stranded small interfering RNA (siRNA), the complex functions as a key tool in gene regulation. The single strand of RNA acts as a template for RISC to recognize complementary DNA, complementary messenger RNA (mRNA) transcription (genetics), transcript. Once found, one of the proteins in RISC, Argonaute, activates and cleaves the mRNA. This process is called RNA interference (RNAi) and it is found in many eukaryotes; it is a key process in defense against viral disease, viral infections, as it is triggered by the presence of double-stranded RNA (dsRNA). Discovery The biochemistry, biochemical identification of RISC was conducted by Gregory Hannon and his colleagues at the Cold Spring Harbor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Argonaute
The Argonaute protein family, first discovered for its evolutionarily conserved stem cell function, plays a central role in RNA silencing processes as essential components of the RNA-induced silencing complex (RISC). RISC is responsible for the gene silencing phenomenon known as RNA interference (RNAi). Argonaute proteins bind different classes of small non-coding RNAs, including microRNAs (miRNAs), small interfering RNAs (siRNAs) and Piwi-interacting RNAs (piRNAs). Small RNAs guide Argonaute proteins to their specific targets through sequence complementarity (base pairing), which then leads to mRNA cleavage, translation inhibition, and/or the initiation of mRNA decay. The name of this protein family is derived from a mutant phenotype resulting from mutation of AGO1 in ''Arabidopsis thaliana'', which was likened by Bohmert et al. to the appearance of the pelagic octopus '' Argonauta argo''. RNA interference RNA interference (RNAi) is a biological process in which RNA mo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dicer
Dicer, also known as endoribonuclease Dicer or helicase with RNase motif, is an enzyme that in humans is encoded by the gene. Being part of the RNase III family, Dicer cleaves double-stranded RNA (dsRNA) and pre-microRNA (pre-miRNA) into short double-stranded RNA fragments called small interfering RNA and microRNA, respectively. These fragments are approximately 20–25 base pairs long with a two-base overhang on the 3′-end. Dicer facilitates the activation of the RNA-induced silencing complex (RISC), which is essential for RNA interference. RISC has a catalytic component Argonaute, which is an endonuclease capable of degrading messenger RNA (mRNA). Discovery Dicer was given its name in 2001 by Stony Brook PhD student Emily Bernstein while conducting research in Gregory Hannon's lab at Cold Spring Harbor Laboratory. Bernstein sought to discover the enzyme responsible for generating small RNA fragments from double-stranded RNA. Dicer's ability to generate aroun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exportin-5
Exportin-5 (XPO5) is a protein that, in humans, is encoded by the ''XPO5'' gene. In Eukaryote, eukaryotic cells, the primary purpose of XPO5 is to export MicroRNA, pre-microRNA (also known as pre-miRNA) out of the Cell nucleus, nucleus and into the cytoplasm, for further processing by the Dicer enzyme. Once in the cytoplasm, the microRNA (also known as miRNA) can act as a gene silencer by regulating Translation (biology), translation of Messenger RNA, mRNA. Although XPO5 is primarily involved in the transport of MicroRNA, pre-miRNA, it has also been reported to transport tRNA. Much research on XPO5 is ongoing. miRNA is a prominent research topic due to its potential use as a therapeutic, with several miRNA-based drugs already in use. Mechanism Binding to pre-miRNA After RanGTP binds to XPO5, the XPO5-RanGTP complex forms a U-like structure to hold the pre-miRNA. The XPO5-RanGTP complex recognizes pre-miRNA by its two-nucleotide Directionality (molecular biology), 3’ overha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stem-loop
Stem-loops are nucleic acid Biomolecular structure, secondary structural elements which form via intramolecular base pairing in single-stranded DNA or RNA. They are also referred to as hairpins or hairpin loops. A stem-loop occurs when two regions of the same nucleic acid strand, usually Complementarity (molecular biology), complementary in nucleotide sequence, base-pair to form a double helix that ends in a loop of unpaired nucleotides. Stem-loops are most commonly found in RNA, and are a key building block of many RNA biomolecular structure#Secondary structure, secondary structures. Stem-loops can direct RNA folding, protect structural stability for messenger RNA (mRNA), provide recognition sites for RNA-binding protein, RNA binding proteins, and serve as a Substrate (chemistry), substrate for Enzyme catalysis, enzymatic reactions. Formation and stability The formation of a stem-loop is dependent on the stability of the helix and loop regions. The first prerequisite is the p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DGCR8
The microprocessor complex subunit DGCR8 ''(DiGeorge syndrome critical region 8)'' is a protein that in humans is encoded by the gene. In other animals, particularly the common model organisms ''Drosophila melanogaster'' and ''Caenorhabditis elegans'', the protein is known as ''Pasha'' (partner of Drosha). It is a required component of the RNA interference pathway. Function The subunit DGCR8 is localized to the cell nucleus and is required for microRNA (miRNA) processing. It binds to the other subunit Drosha, an RNase III enzyme, to form the microprocessor complex that cleaves a primary transcript known as pri-miRNA to a characteristic stem-loop structure known as a pre-miRNA, which is then further processed to miRNA fragments by the enzyme Dicer. DGCR8 contains an RNA-binding domain and is thought to bind pri-miRNA to stabilize it for processing by Drosha. DGCR8 is also required for some types of DNA repair. Removal of UV-induced DNA photoproducts, during transcription ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drosha
Drosha is a Class 2 ribonuclease III enzyme that in humans is encoded by the ''DROSHA'' (formerly ''RNASEN'') gene. It is the primary nuclease that executes the initiation step of miRNA processing in the nucleus. It works closely with DGCR8 and in correlation with Dicer. It has been found significant in clinical knowledge for cancer prognosis. and HIV-1 replication. History Human Drosha was cloned in 2000 when it was identified as a nuclear dsRNA ribonuclease involved in the processing of ribosomal RNA precursors. The other two human enzymes that participate in the processing and activity of miRNA are the Dicer and Argonaute proteins. Recently, proteins like Drosha have been found significant in cancer prognosis and HIV-1 replication. Function Members of the ribonuclease III superfamily of double-stranded (ds) RNA-specific endoribonucleases participate in diverse RNA maturation and decay pathways in eukaryotic and prokaryotic cells. The RNase III Drosha is the core nucl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ribonuclease III
Ribonuclease III (RNase III or RNase C) (BREND3.1.26.3 is a type of ribonuclease that recognizes dsRNA and cleaves it at specific targeted locations to transform them into mature RNAs. These enzymes are a group of endoribonucleases that are characterized by their ribonuclease domain, which is labelled the RNase III domain. They are ubiquitous compounds in the cell and play a major role in pathways such as RNA precursor synthesis, RNA Silencing, and the ''pnp'' autoregulatory mechanism. Types of RNase III The RNase III superfamily is divided into four known classes: 1, 2, 3, and 4. Each class is defined by its domain structure.Liang Y-H, Lavoie M, Comeau M-A, Elela SA, Ji X. Structure of a Eukaryotic RNase III Post-Cleavage Complex Reveals a Double- Ruler Mechanism for Substrate Selection. Molecular cell. 2014;54(3):431-444. doi:10.1016/j.molcel.2014.03.006. Class 1 RNase III *Class 1 RNase III enzymes have a homodimeric structure whose function is to cleave dsRNA into multiple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microprocessor Complex
The microprocessor complex is a protein complex involved in the early stages of processing microRNA (miRNA) and RNA interference (RNAi) in animal cells. The complex is minimally composed of the ribonuclease enzyme Drosha and the dimeric RNA-binding protein DGCR8 (also known as Pasha in non-human animals), and cleaves primary miRNA substrates to pre-miRNA in the cell nucleus. Microprocessor is also the smaller of the two multi-protein complexes that contain human Drosha. Composition The microprocessor complex consists minimally of two proteins: Drosha, a ribonuclease III enzyme; and DGCR8, a double-stranded RNA RNA-binding protein, binding protein. (DGCR8 is the name used in mammalian genetics, abbreviated from "DiGeorge syndrome critical region 8"; the homologous protein in model organisms such as Drosophila melanogaster, flies and Caenorhabditis elegans, worms is called ''Pasha'', for ''Pa''rtner of Dro''sha''.) The stoichiometry of the minimal complex was at one point expe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
