On the rules of engagement for microRNAs targeting protein coding regions.

MiRNAs post-transcriptionally repress gene expression by binding to mRNA 3'UTRs, but the extent to which they act through protein coding regions (CDS regions) is less well established. MiRNA interaction studies show a substantial proportion of binding occurs in CDS regions, however sequencing studies show much weaker effects on mRNA levels than from 3'UTR interactions, presumably due to competition from the translating ribosome. Consequently, most target prediction algorithms consider only 3'UTR interactions. However, the consequences of CDS interactions may have been underestimated, with the reporting of a novel mode of miRNA-CDS interaction requiring base pairing of the miRNA 3' end, but not the canonical seed site, leading to repression of translation with little effect on mRNA turnover. Using extensive reporter, western blotting and bioinformatic analyses, we confirm that miRNAs can indeed suppress genes through CDS-interaction in special circumstances. However, in contrast to that previously reported, we find repression requires extensive base-pairing, including of the canonical seed, but does not strictly require base pairing of the 3' miRNA terminus and is mediated through reducing mRNA levels. We conclude that suppression of endogenous genes can occur through miRNAs binding to CDS, but the requirement for extensive base-pairing likely limits the regulatory impacts to modest effects on a small subset of targets.

Down-regulation of TGF-ß, VEGF, and bFGF in vascular endothelial cells of chicken induced by a brittle star (Ophiocoma erinaceus) extract.

Great attention has been focused on the discovery of anti-angiogenic natural and synthetic compounds to be finally used as or at least a part of the treatment of tumors. The marine ecosystems provide diversity in natural chemicals with the potential of being exploited as medicines in the treatment of diseases. Several studies have investigated Ophiuroids as a source of anti-tumor and anti-metastatic organisms. Here, we described the inhibitory effects of an ethanolic crude extract of brittle star (Ophiocoma erinaceus) on angiogenesis and the expression level of TGF-ß, VEGF, and bFGF in chicken chorioallantoic membrane (CAM) as an experimental model. To do this 45 embryonated eggs were randomly divided into six groups including the control group, sham, three experimental groups and positive. The number and the length of vessels were calculated using ImageJ® software. The relative mRNA levels of the genes in different groups were evaluated by qRT-PCR method. Our study was suggestive of an anti-angiogenesis effect of brittle star ethanolic crude extract in a CAM model. The extract also showed a pharmacological effect of down-regulation of mRNA related to VEGF, TGF-ß, and bFGF genes on chicken vascular endothelial cells. It was also showed that the observed inhibitory effect is with a dose-dependent manner in which the highest inhibitory effect belonged to the highest used dose. We indicated the anti-angiogenesis properties of the Persian Gulf brittle star. Further studies are needed in other aspects of the brittle star extract in the treatment of angiogenesis, hyperplasia, and cancers.