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miRNA biogenesis in plants differs from animal biogenesis mainly in the steps of nuclear processing and export. Instead of being cleaved by two different enzymes, once inside and once outside the nucleus, both cleavages of the plant miRNA are performed by a Dicer homolog, called Dicer-like1 (DL1). DL1 is expressed only in the nucleus of plant ...
The RNase III Dicer is a critical member of RISC that initiates the RNA interference process by producing double-stranded siRNA or single-stranded miRNA. Enzymatic cleavage of dsRNA within the cell produces the short siRNA fragments of 21-23 nucleotides in length with a two-nucleotide 3' overhang.
The lethal-7 (let-7) gene was first discovered in the nematode C. elegans as a key developmental regulator and became one of the first two known microRNAs (the other one is lin-4). [8] Soon, let-7 was found in the fruit fly (Drosophila), and identified as the first known human miRNA by a BLAST (basic local alignment search tool) research. [9]
These two proteins homeostatically control miRNA biogenesis by an auto-feedback loop. [16] A 2nt 3' overhang is generated by Drosha in the nucleus recognized by Dicer in the cytoplasm, which couples the upstream and downstream processing events. Pre-miRNA is then further processed by the RNase Dicer into mature miRNAs in the cell cytoplasm.
The microprocessor complex consists minimally of two proteins: Drosha, a ribonuclease III enzyme; and DGCR8, a double-stranded RNA binding protein. [4] [5] [6] (DGCR8 is the name used in mammalian genetics, abbreviated from "DiGeorge syndrome critical region 8"; the homologous protein in model organisms such as flies and worms is called Pasha, for Partner of Drosha.)
microRNA mediated repression occurs in two ways, either by translational repression or stimulating mRNA decay. miRNA recruit the RISC complex to the mRNA to which they are bound. The link to P-bodies comes by the fact that many, if not most, of the proteins necessary for miRNA gene silencing are localized to P-bodies, as reviewed by Kulkarni et ...
An miRNA that remains constant in its expression through these stages is proposed to have a role in regulating general aspects of cell physiology. [8] Thus it was becoming evident in 2003 shortly after its discovery, that the mir-92 miRNA and associated family members are providing functional roles to the cell cycle and to cell signalling, and ...
Dicer, also known as endoribonuclease Dicer or helicase with RNase motif, is an enzyme that in humans is encoded by the DICER1 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.