pre-miRNA processing
Definition
Target type: biologicalprocess
A process involved in the conversion of a pre-microRNA transcript into a mature microRNA molecule. [GOC:sl, PMID:15211354]
Pre-miRNA processing is a crucial step in the biogenesis of microRNAs (miRNAs), small non-coding RNA molecules that regulate gene expression. This intricate process involves the precise cleavage of a primary miRNA transcript (pri-miRNA) into a mature miRNA that can bind to target messenger RNAs (mRNAs) and silence their translation. The process can be broadly divided into two main stages: nuclear processing and cytoplasmic processing.
**Nuclear Processing:**
1. **Transcription:** The first step begins with the transcription of a primary miRNA transcript (pri-miRNA) by RNA polymerase II. This pri-miRNA is a long, hairpin-shaped RNA molecule with a 5' cap and a 3' poly(A) tail.
2. **Drosha Processing:** The pri-miRNA is recognized and cleaved by a microprocessor complex, which consists of the RNase III enzyme Drosha and the double-stranded RNA-binding protein DGCR8. Drosha cleaves the pri-miRNA at specific sites, generating a shorter precursor miRNA (pre-miRNA) that is typically 70-100 nucleotides in length. This cleavage event releases the pre-miRNA from the longer pri-miRNA molecule.
**Cytoplasmic Processing:**
3. **Export:** The pre-miRNA is then exported from the nucleus to the cytoplasm by the nuclear export protein Exportin-5. This transport step requires the recognition of the 2-nucleotide 3' overhang that is generated by Drosha processing.
4. **Dicer Processing:** Once in the cytoplasm, the pre-miRNA is further processed by another RNase III enzyme called Dicer. Dicer, in association with its partner protein TRBP, cleaves the pre-miRNA at the terminal loop, generating a mature miRNA duplex of approximately 22 nucleotides.
5. **Unwinding and Incorporation:** The mature miRNA duplex is unwound, and one strand, designated as the guide strand, is incorporated into a protein complex called the RNA-induced silencing complex (RISC). The other strand, the passenger strand, is typically degraded.
**Mature miRNA Function:**
6. **Target Recognition:** The mature miRNA, now incorporated into RISC, can bind to complementary sequences in target mRNAs. This interaction can lead to translational repression or mRNA degradation, depending on the degree of complementarity between the miRNA and its target mRNA.
**Overall, pre-miRNA processing is a highly regulated and essential process that ensures the production of functional miRNAs, which play critical roles in diverse cellular processes, including development, differentiation, and disease.**'
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Proteins (2)
| Protein | Definition | Taxonomy |
|---|---|---|
| Protein argonaute-2 | A protein argonaute-2 that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q9UKV8] | Homo sapiens (human) |
| RISC-loading complex subunit TARBP2 | A RISC-loading complex subunit TARBP2 that is encoded in the genome of human. [PRO:DNx, UniProtKB:Q15633] | Homo sapiens (human) |
Compounds (6)
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| enoxacin | enoxacin : A 1,8-naphthyridine derivative that is 1,4-dihydro-1,8-naphthyridine with an ethyl group at the 1 position, a carboxy group at the 3-position, an oxo sustituent at the 4-position, a fluoro substituent at the 5-position and a piperazin-1-yl group at the 7 position. An antibacterial, it is used in the treatment of urinary-tract infections and gonorrhoea. Enoxacin: A broad-spectrum 6-fluoronaphthyridinone antibacterial agent that is structurally related to NALIDIXIC ACID. | 1,8-naphthyridine derivative; amino acid; fluoroquinolone antibiotic; monocarboxylic acid; N-arylpiperazine; quinolone antibiotic | antibacterial drug; DNA synthesis inhibitor |
| sulfaguanidine | sulfaguanidine : A sulfonamide incorporating a guanidine moiety used to block the synthesis of folic acid; mostly used in veterinary medicine Sulfaguanidine: A sulfanilamide antimicrobial agent that is used to treat enteric infections. | sulfonamide antibiotic | antiinfective agent |
| sulfanilamide | substituted aniline; sulfonamide; sulfonamide antibiotic | antibacterial agent; drug allergen; EC 4.2.1.1 (carbonic anhydrase) inhibitor | |
| sulfisomidine | sulfisomidine : A sulfonamide consisting of pyrimidine having methyl substituents at the 2- and 6-positions and a 4-aminobenzenesulfonamido group at the 4-position. Sulfisomidine: A sulfanilamide antibacterial agent. | pyrimidines; sulfonamide; sulfonamide antibiotic | antiinfective agent |
| uridine monophosphate | uridine 5'-monophosphate : A pyrimidine ribonucleoside 5'-monophosphate having uracil as the nucleobase. Uridine Monophosphate: 5'-Uridylic acid. A uracil nucleotide containing one phosphate group esterified to the sugar moiety in the 2', 3' or 5' position. | pyrimidine ribonucleoside 5'-monophosphate; uridine 5'-phosphate | Escherichia coli metabolite; human metabolite; mouse metabolite |
| schisanhenol b | schisanhenol B: isolated from kernels of Schisandra rubriflora; structure given in first source |