title: Does base-pairing strength play a role in microRNA repression?
abstract: MicroRNAs (miRNAs) are short, single-stranded RNAs that silence gene expression by either degrading mRNA or repressing translation. Each miRNA regulates a specific set of mRNA "targets" by binding to complementary sequences in their 3' untranslated region. In this study, we examined the importance of the base-pairing strength of the miRNA-target duplex to repression. We hypothesized that if base-pairing strength affects the functionality of miRNA repression, organisms with higher body temperature or that live at higher temperatures will have miRNAs with higher G/C content so that the miRNA-target complex will remain stable. In the nine model organisms examined, we found a significant correlation between the average G/C content of miRNAs and physiological temperature, supporting our hypothesis. Next, for each organism examined, we compared the average G/C content of miRNAs that are conserved among distant organisms and that of miRNAs that are evolutionarily recent. We found that the average G/C content of ancient miRNAs is lower than recent miRNAs in homeotherms, whereas the trend was inversed in poikilotherms, suggesting that G/C content is associated with temperature, thus further supporting our hypothesis. In the organisms examined, the average G/C content of miRNA "seed" sequences was higher than that of mature miRNAs, which was higher than pre-miRNA loops, suggesting an association between the degree of functionality of the sequence and its average G/C content. Our analyses show a possible association between the base-pairing strength of miRNA-targets and the temperature of an organism, suggesting that base-pairing strength plays a role in repression by miRNAs.
authors.affiliation: Department of Entomology, The Hebrew University, Rehovot 76100, Israel.
authors.forename: Ido
authors.initials: I
authors.lastname: Carmel
authors.forename: Noam
authors.initials: N
authors.lastname: Shomron
authors.forename: Yael
authors.initials: Y
authors.lastname: Heifetz
mesh_terms: D000818:Animals; D001482:Base Composition; D020029:Base Pairing; D001831:Body Temperature / Q000235:genetics / Q000502:physiology; D006801:Humans; D035683:MicroRNAs / Q000737:chemistry / Q000235:genetics*; D034622:RNA Interference; D013816:Thermodynamics
chemical_list: D035683:MicroRNAs