MicroRNA - Volume 5, Issue 1, 2016

Inflammatory bowel diseases, including Crohn’s Disease and Ulcerative Colitis, result from a dysregulated inflammatory response to environmental factors in genetically predisposed individuals. The list of genetic factors involved in the development of these diseases has considerably increased in last years. However, recently, new promising insights on inflammatory bowel diseases have been produced by studies on microRNAs. MicroRNAs are small non coding RNA molecules, that play a pivotal role in gene expression and regulation. They are involved in many biological processes, such as cellular proliferation and differentiation, signal transduction and, more recently, they have been recognized as also having a role in the innate and adaptative response. In this review we give an overview on the role of microRNAs in the pathogenesis of inflammatory bowel diseases.

Malignant Pleural Mesothelioma (MPM) is an aggressive disease characterized by a dismal prognosis, mainly due to late diagnosis. To date, there are very few treatment options available and the refractoriness to the majority of therapeutic strategies, leading to consider MPM a relevant problem in public health. Therefore, the identification of novel prognostic markers and alternative therapeutic strategies remain a top priority. Several efforts have been made in this direction and to date a number of studies have investigated the role of microRNA as biomarkers in MPM, identifying the potential prognostic role of miR-29c* and miR-31. Very recently, the first microRNA signature able to discriminate poor or and good prognosis of MPM patients underwent surgery has been published. Very interestingly, several microRNA such as miR-1, miR-16, and miR-34b/c have been identified as potential therapeutic agents. Indeed, the forced expression of these microRNA resulted in anti-tumor effects both in vitro and in vivo. Besides, the introduction of microRNA mimic, some agents such as EphrinA1 and Onconase, seemed to exert anti-tumor effects through specific microRNA. Moreover, microRNA have also been reported to play a role in chemoresistance enhancing the sensitivity to specific drug such as pemetrexed. In this review the most relevant and updated data about the role of microRNA as prognostic markers and therapeutic agents in MPM will be presented, opening new avenues towards improved management of this aggressive disease.

Background: The miR-106a-363 cluster, encoding six miRNAs (miR- 106a, miR-18b, miR-20b, miR-19b-2, miR-92-2 and miR-363), has been shown to be overexpressed in various tumours. In oral carcinoma cells, however only miR- 106a was detectable from this cluster. We have investigated how effects of transfection of oral carcinoma cells with a non-expressed member of this cluster affect mRNA transcriptomes and cellular selected functions. Methods: Investigate effects of miR-20b and miR-363 mimics on cellular respiration, glycolysis and mobility. Effects on mRNA transcriptomes were monitored using microarrays. Results: The studies show that in oral carcinoma cells transfected with miR-20b -, or miR-363-3p or miR-363-5p mimic different mRNAs were differentially expressed. Nevertheless, bioinformatics analysis suggested significant associations of differentially expressed genes to inhibition of cellular proliferation, cell cycle and cellular migration. These results were also experimentally confirmed. Conclusions: Transfection of miRNA mimics for unexpressed members of the miR-106a-363 cluster (miR20b, miR-363-3p and miR-363-5p) exhibit an anti-proliferative effect on oral carcinoma cells, although likely mediated by different regulatory mechanisms.

Background: miR-144 has potential benefits in protecting against myocardial ischemia and suppression of tumor growth. We have previously shown that a single intravenous injection of miR-144 provides potent cardioprotection, but its kinetics and distribution are not known. Methods: Single stranded mature miR-144 or Cy3-labelled-miR-144 was delivered into C57/B6 mice by tail vein injection. Results: After intravenous injection, the signal of Cy3-labelled-miR-144 in the kidney, brain, heart and liver peaks at 60 minutes, and is predominantly localised to the endothelium at that stage. In the kidney and heart, Cy3-labelled-miR-144 signal is detectable within the parenchymal tissues for at least 3 days, after which it starts to decrease, but brain Cy3-miR-144 signal rapidly decreases after 1 hour, and is lost at day 1, with no parenchymal uptake detected. Cy3-miR-144 signal can be detected until day 28 in the liver. Stem loop RTPCR confirmed the temporal pattern shown by miR-144 in kidney, brain and heart, but in liver there was a continuous rise following the initial injection until day 28 with no signs of decrease, suggesting de-novo synthesis. Conclusion: There is early endothelial uptake of injected miR-144 followed by organ-specific distribution and kinetics. In the liver, there appears to be a positive feedback process that leads to continued accumulation of miR-144 that persists for at least 28 days. These observations should be taken into account when designing experiments utilizing parenteral miR-144 and assessing the biology of its actions.

Introduction: MicroRNA (miR) is non-coding small RNA that regulate mRNA at the post-transcriptional level by degradation or inhibition. To find physical stress markers, we developed a rat model involving a simple and complicated stress and measured serum miR levels. Materials and Methods: To demonstrate changes in serum miR levels when physical stress is applied, we constructed three stress modalities using rats: alcohol intake, treadmill running and restraint. After alcohol administration, the rats were made to run on a treadmill and some of the rats were further stressed by restraining with a 2 kg water bag immediately after the treadmill run. The rats were grouped as follows: control, run for 20 min, run for 90 min, run and restrained for 20 min, run and restrained for 90 min. Using total RNA extracted from sera, expression levels of eight miRs were measured by real-time PCR. Results: The level of miR-199a was increased by 20 min stress procedures and the levels of miR-1, miR-24a and miR-133a/b were increased by 90 min stress procedures. No change in the levels of miR-208, miR-212 or miR-296-5p was seen under any stress conditions. There was no significant difference between a treadmill run only and a combination of treadmill run and being restrained by a 2 kg water bag. Discussion: We demonstrated that a combination of these serum miRs might indicate the intensity of stress experienced.

Background: The initiation of β-cell proliferation to recover reduced β-cell mass is considered as one of the attractive therapeutic approaches for type 1 and 2 diabetes. In this study, we investigated the involvement of miRNAs in β-cell proliferation. Methods: Global miRNA array analysis of pancreas tissue was carried out using a 60% partial pancreatectomy (PPx) rodent model, which is a well-characterized model for pancreatic regeneration with accelerated proliferation of β-cells. To explore miRNAs with mitogenic activity on β-cells, precursors and antisense oligonucleotides (ASOs) for miRNAs were transfected into a primary islet monolayer cell cultures isolated from adult rats in order to modify their expression and proliferation of β-cells. Results: We found that miR-199b-5p, which was up-regulated 2.6 times in the pancreas of the PPx treated group, significantly enhanced the proliferation of β-cells when its precursor was over-expressed. Target genes of miR-199b-5p were investigated and Mixed lineage kinase-3 (MLK3) was identified as one of the candidates since its expression was down-regulated through an interaction with miR-199b-5p and siRNA treatment for MLK3 enhanced the proliferation of β-cells. Conclusion: Our data suggest that the up-regulation of miR-199b-5p enhances proliferation of β-cells at least in part through down-regulation of MLK3.

Background: MicroRNAs (miRNAs) are endogenous small non-coding RNAs with 18-24 nucleotides in length, which have important roles in posttranscriptional gene regulation. The resemblance of miRNA biogenesis in unicellular green algae and those in plants suggests probable evolutionary conserved pathways. This conservation provides a ground towards prediction of new homologs via computational biology. Methods: Here, conserved miRNA genes in Chlamydomonas reinhardtii and plants were examined through homology alignment. Previously known and unique plant miRNAs were BLASTed against expressed sequence tags (ESTs) and genomic survey sequences (GSSs) of C. reinhardtii. All candidate sequences with appropriate fold back structures were screened according to a series of miRNA filtering criteria. Results: Homologous miRNAs (17), belonging to 9 miRNA gene families were predicted. Interestingly and for the first time, a miRNA family of genes was localized to chloroplast. Again and for the first time, here we report identification of C. reinhardtii miRNA orthologs in plants and animals. miRNA target genes were identified based on their sequence complementarities to the respective miRNAs using psRNATarget against C. reinhardtii, Unigene, and DFCI Gene Index (CHRGI). Totally, 152 potential target sites were identified. From the predicted miRNAs, 7 miRNAs had no target sequence in C. reinhardtii protein coding genes. Conclusion: Identifying miRNA and their target transcript(s) would be useful for other research concerned with the function and regulatory mechanisms of C. reinhardtii miRNAs and helps researchers to better understand the nature of its extensive metabolic flexibility and environmental compatibility to survive in distinct environmental niches and nutrient availability.