User:antonio marco/Mir-2 microRNA precursor
| mir-2 microRNA precursor | |
|---|---|
| Predicted secondary structure and sequence conservation of mir-2 | |
| Identifiers | |
| Symbol | mir-2 |
| Rfam | RF00047 |
| miRBase | MI0000117 |
| miRBase family | MIPF0000049 |
| Other data | |
| RNA type | Gene; miRNA |
| Domain(s) | Eukaryota |
| GO | GO:0035195 GO:0035068 |
| SO | SO:0001244 |
| PDB structures | PDBe |
The mir-2 microRNA (miRNA) family includes the microRNA genes mir-2 and mir-13 (MIPF0000049). Mir-2 is widespread in invertebrates, and it is the largest family of microRNAs in the model species Drosophila melanogaster . MicroRNAs from this family are produced from the 3' arm of the precursor hairpin.[1] Leaman et al. showed that the miR-2 family regulates cell survival by translational repression of proapoptotic factors.[2] Based on computational prediction of targets, a role in neural development and maintenance has been suggested.[1]
Species distribution
[edit ]The mir-2 family is specific to protostomes.[1] There are 8 mir-2-related loci in Drosophila melanogaster : mir-2a-1, mir-2a-2, mir-2b-1, mir-2b-2, mir-2c, mir-13a, mir-13b-1 and mir-13b-2.[3] Most other insect genomes host five mir-2 loci [4] although the number varies in other invertebrates.[1] Mir-13 subfamily emerged from mir-2 sequences before the insect radiation.[1]
Although mir-11 and mir-6 have similar sequences to mir-2 microRNAs, they are not evolutionarily related[1] , and therefore should not be considered from the same microRNA family.
Mir-2 hairpin precursor sequences are highly conserved, in particular in their 3' arm in which the first 10 nucleotides are identical to all family members. Functional mir-2 microRNAs come from the 3' arm of the precursors, and most of them have the same Drosha processing point.[1] [3] [5] That means that the seed sequence is virtually the same in all these products[6] , hence, they should target the same transcripts.
Mir-2 microRNAs are organized in a large cluster in most insects. This cluster has typically 5 members of the mir-2 family plus mir-71, an evolutionarily unrelated microRNA.[4] [1] The number of mir-2 sequences differs among invertebrate lineages although they remain tightly clustered in the genome. A notable exception has been observed in Drosophila melanogaster , in which the mir-2 family is organized in two clusters and two single loci.[3] Additionally, mir-7 microRNA has been lost in the Drosophila lineage.[4]
Origin and evolution
[edit ]The mir-2 family originated before the last common ancestor of protostomes, and has been ever since linked to mir-71.[1] The evolution of mir-2 is characterized by successive expansions by duplication events. Since most paralogous microRNAs conserve their function, it has been suggested that mir-2 evolution is dominated by a birth-and-death dynamics driven by random drift.[1]
One mir-2 microRNA in Drosophila, dme-miR-2a-2[1], is two nucleotides offset with respect to the canonical products of other mir-2 precursors.[5] This is likely to affect the function of that particular microRNA. This functional shift is associated to a change in the genomic distribution of mir-2 sequences in Drosophila. The functional diversification of microRNAs may require breaking the genomic linkage between paralogs, probably to avoid the co-regulation of multiple products by the same regulatory sequences.[1]
In the human parasite Schistosoma mansoni the whole mir-71/mir-2 cluster has been duplicated, and one of the copies is in the sexual chromosome.[7]
Targets of mir-2/mir-13
[edit ]Mir-2 microRNAs in Drosophila specifically target three pro-apoptotic genes: rpr, grim and skl.[2] The repression of rpr and grim by the Hox gene ABD-B prevents apoptosis in neural cells. [8] On the other hand, computational prediction of microRNA targets show that mir-2 may target neural genes in both Drosophila and Caenorhabditis elegans .[1] All this suggests a conserved role of mir-2 in neural development and maintenance.[1] However, further experiments are required to confirm this association.
See also
[edit ]References
[edit ]- ^ a b c d e f g h i j k l m Marco, A; Hooks, KB; Griffiths-Jones, S (2011). "UPDATE". RNA Biology: 0–1.
- ^ a b Leaman, Dan; Chen, Po Yu; Fak, John; Yalcin, Abdullah; Pearce, Michael; Unnerstall, Ulrich; Marks, Debora S.; Sander, Chris; Tuschl, Thomas; Gaul, Ulrike (2005). "Antisense-mediated depletion reveals essential and specific functions of microRNAs in Drosophila development". Cell. 121 (7): 1097–1108. doi:10.1016/j.cell.2005年04月01日6. PMID 15989958.
{{cite journal}}: CS1 maint: date and year (link) - ^ a b c Ruby, JG; Stark, A; Johnston, WK; Kellis, M; Bartel, DP; Lai, EC (2007). "Evolution, biogenesis, expression, and target predictions of a substantially expanded set of Drosophila microRNAs". Genome Res. 17 (12): 1850–64. doi:10.1101/gr.6597907. PMC 2099593 . PMID 17989254.
- ^ a b c Marco, A; Hui, JH; Ronshaugen, M; Griffiths-Jones, S (2010). "Functional shifts in insect microRNA evolution". Genome Biol Evol. 2: 686–96. doi:10.1093/gbe/evq053. PMC 2956262 . PMID 20817720.
- ^ a b Wang, X; Liu, S (2011). "Systematic curation of miRBase annotation using integrated small RNA high-throughput sequencing data for C. elegans and Drosophila". Front Gene. 2: 686–696. doi:10.1093/gbe/evq053. PMC 2956262 . PMID 20817720.
- ^ Bartel, DP (2009). "MicroRNAs: target recognition and regulatory functions". Cell. 136 (2): 215–33. doi:10.1016/j.cell.200901002. PMC 3794896 . PMID 19167326.
- ^ Gomes, M; Muniyappa, MK; Carvalho, SG; Guerra-Sa, R; Spillane, C (2011). "Genome-wide identification of novel microRNAs and their target genes in the human parasite Schistosoma mansoni". Genomics. 98 (2): 96–111. doi:10.1016/j.ygeno.201105007. PMID 21640815.
- ^ Miguel-Aliaga, I; Thor, S (2004). "Segment-specific prevention of pioneer neuron apoptosis by cell-autonomous, postmitotic Hox gene activity". Development. 131 (24): 6093–105. doi:10.1242/dev.01521. PMID 15537690.