Kilik
Joined: 29 Jun 2005
Posts: 84
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 Posted: Fri Feb 16, 2007 4:44 am Post subject: Why is the microRNA of different species unrelated?
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People always proclaim, all species share the same and very similar DNA. Why then, is micro rna from different species so different , work in different ways, and totally different in structure?
Since you probably didn't know, here is some info-
http://www.wi.mit.edu/news/archives/2006/cpa_0505.html
Why is the microRNA of different species so different?
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=523849
| Quote: | Five different papers have recently appeared that used computational approaches to predict microRNA targets in Drosophila [5-7], and mammals [8,9]. These studies only considered hits occurring within 3'-UTR regions that were conserved across related species, and favored or required a short region of perfect complementarity towards the 5'-end of microRNAs. However, there is reason to suspect that the rules governing microRNA-target interactions may not be universal. For example, in plants, most of the known microRNAs bind in a perfect or near-perfect manner to mRNA targets located within the protein coding region (cds) [10,11]. In contrast, in C. elegans [12] and Drosophila [13], known microRNAs lack long stretches (>10) of complementarity with their targets and generally interact within the 3'-untranslated region (3'-UTR). Furthermore, whereas the 5'-ends of many Drosophila microRNAs recognize 5–6 nt. common motifs within the target, these motifs are not a general feature of mammalian microRNAs [14]. Thus, it is conceivable that human microRNA targets do not follow the same constraints as observed in C. elegans and Drosophila.
In the present paper, we have performed an unbiased statistical analysis of the manner in which human microRNAs interact complementarily with human mRNAs present in the NCBI human RefSeq database, looking for characteristics that differ significantly as compared with scrambled versions of the same microRNA sequences. The results demonstrate several novel features of human microRNA-mRNA interactions that differ from C. elegans and Drosophila, and identify a short-list of promising candidate microRNA-mRNA target pairs that are unlikely to have arisen by chance. |
C. elegans
http://en.wikipedia.org/wiki/Caenorhabditis_elegans
Drosophila
http://en.wikipedia.org/wiki/Drosophila
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In humans, protein expression largely depends on a “microRNA code” - a highly integrated functional network within which microRNA molecules work in a cooperative manner. MicroRNA show specific expression profiles in different normal / pathological cells and tissues, and are directly involved in numerous pathologies such as cancers, CNS diseases, metabolic diseases and certain viral infections. However, only a subset of these microRNA and their targets are known today. Actigenics has developed a powerful discovery platform that allows identification, validation and analysis of microRNA and their function in any cellular and tissue context. Well-designed algorithms allow identification of the set of functional targets for each microRNA and of the subset of microRNA acting in a coordinated fashion to regulate specific biological processes. |
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