A Database for TSSs of Human MicroRNAs

MicroRNAs (miRNAs) are small endogeneous non-coding RNAs of about 22nt length. These short RNAs regulate the expression of mRNAs by hybridizing with their 3'-UTRs or by translational repression. They have been shown to take crucial roles in many biological processes. Many of the current studies are focused over how mature miRNAs regulate mRNAs, even though there is very limited knowledge about their transcriptional loci. Primary miRNAs (pri-miRs) are first transcribed from the DNA, followed by the formation of precursor miRNA (pre-miR) by endonucleases activity, which finally produces mature miRNAs. Unfortunately, the identification of the loci of pri-miRs, and the associated information about transcription start sites (TSSs) and promoters is still in progress. This information, even though limited, may be useful for further study on the regulation of miRNAs. In this paper, we provide a novel database of miRNA TSSs (miRT) that might be a valuable resource for advanced research on miRNA regulation

Identification of novel post-transcriptional features in olfactory receptor family mRNAs.

Olfactory receptor (Olfr) genes comprise the largest gene family in mice. Despite their importance in olfaction, how most Olfr mRNAs are regulated remains unexplored. Using RNA-seq analysis coupled with analysis of pre-existing databases, we found that Olfr mRNAs have several atypical features suggesting that post-transcriptional regulation impacts their expression. First, Olfr mRNAs, as a group, have dramatically higher average AU-content and lower predicted secondary structure than do control mRNAs. Second, Olfr mRNAs have a higher density of AU-rich elements (AREs) in their 3'UTR and upstream open reading frames (uORFs) in their 5 UTR than do control mRNAs. Third, Olfr mRNAs have shorter 3' UTR regions and with fewer predicted miRNA-binding sites. All of these novel properties correlated with higher Olfr expression. We also identified striking differences in the post-transcriptional features of the mRNAs from the two major classes of Olfr genes, a finding consistent with their independent evolutionary origin. Together, our results suggest that the Olfr gene family has encountered unusual selective forces in neural cells that have driven them to acquire unique post-transcriptional regulatory features. In support of this possibility, we found that while Olfr mRNAs are degraded by a deadenylation-dependent mechanism, they are largely protected from this decay in neural lineage cells

Features of mammalian microRNA promoters emerge from polymerase II chromatin immunoprecipitation data

Background: MicroRNAs (miRNAs) are short, non-coding RNA regulators of protein coding genes. miRNAs play a very important role in diverse biological processes and various diseases. Many algorithms are able to predict miRNA genes and their targets, but their transcription regulation is still under investigation. It is generally believed that intragenic miRNAs (located in introns or exons of protein coding genes) are co-transcribed with their host genes and most intergenic miRNAs transcribed from their own RNA polymerase II (Pol II) promoter. However, the length of the primary transcripts and promoter organization is currently unknown. Methodology: We performed Pol II chromatin immunoprecipitation (ChIP)-chip using a custom array surrounding regions of known miRNA genes. To identify the true core transcription start sites of the miRNA genes we developed a new tool (CPPP). We showed that miRNA genes can be transcribed from promoters located several kilobases away and that their promoters share the same general features as those of protein coding genes. Finally, we found evidence that as many as 26% of the intragenic miRNAs may be transcribed from their own unique promoters. Conclusion: miRNA promoters have similar features to those of protein coding genes, but miRNA transcript organization is more complex. © 2009 Corcoran et al

T-ALL and thymocytes : a message of noncoding RNAs

In the last decade, the role for noncoding RNAs in disease was clearly established, starting with microRNAs and later expanded towards long noncoding RNAs. This was also the case for T cell acute lymphoblastic leukemia, which is a malignant blood disorder arising from oncogenic events during normal T cell development in the thymus. By studying the transcriptomic profile of protein-coding genes, several oncogenic events leading to T cell acute lymphoblastic leukemia (T-ALL) could be identified. In recent years, it became apparent that several of these oncogenes function via microRNAs and long noncoding RNAs. In this review, we give a detailed overview of the studies that describe the noncoding RNAome in T-ALL oncogenesis and normal T cell development

The Nefarious Nexus of Noncoding RNAs in Cancer

The past decade has witnessed enormous progress, which has seen the noncoding RNAs (ncRNAs) turn from the so called dark matter RNA to critical functional molecules, influencing most physiological processes in development and disease contexts. Many ncRNAs interact with each other and are part of networks that influence the cell transcriptome and proteome and consequently the outcome of biological processes. The regulatory circuits controlled by ncRNAs have become increasingly more relevant in cancer. Further understanding of these complex network interactions and how ncRNAs are regulated, is paving the way for the identification of better therapeutic strategies in cancer

MicroRNA-143 activation regulates smooth muscle and endothelial cell crosstalk in pulmonary arterial hypertension

Rationale: The pathogenesis of PAH remains unclear. The four microRNAs representing the miR-143 and miR-145 stem loops are genomically clustered. Objective: To elucidate the transcriptional regulation of the miR-143/145 cluster, and the role of miR-143 in PAH. Methods and Results: We identified the promoter region that regulates miR-143/145 miRNA expression in pulmonary artery smooth muscle cells (PASMCs). We mapped PAH-related signalling pathways, including estrogens receptor (ER), liver X factor/retinoic X receptor (LXR/RXR), TGF-β (Smads), and hypoxia (HRE) that regulated levels of all pri-miR stem loop transcription and resulting miRNA expression. We observed that miR-143-3p is selectively upregulated compared to miR-143-5p during PASMC migration. Modulation of miR-143 in PASMCs significantly altered cell migration and apoptosis. In addition, we found high abundance of miR-143-3p in PASMCs-derived exosomes. Using assays with pulmonary arterial endothelial cells (PAECs) we demonstrated a paracrine pro-migratory and pro-angiogenic effect of miR-143-3p enriched exosomes from PASMC. Quantitative PCR and in situ hybridisation showed elevated expression of miR-143 in calf models of PAH as well as in samples from PAH patients. Moreover, in contrast to our previous findings that had not supported a therapeutic role in vivo, we now demonstrate a protective role for miR-143 in experimental PH in vivo in miR-143-/- and antimiR143-3p-treated mice exposed to chronic hypoxia in both preventative and reversal settings. Conclusions: MiR-143-3p modulated both cellular and exosome-mediated responses in pulmonary vascular cells, while inhibition of miR-143-3p blocked experimental PH. Taken together these findings confirm an important role for the miR-143/145 cluster in PAH pathobiology

The CD4+ T cell methylome contributes to a distinct CD4+ T cell transcriptional signature in Mycobacterium bovis-infected cattle

peer-reviewedWe hypothesised that epigenetic regulation of CD4+ T lymphocytes contributes to a shift toward a dysfunctional T cell phenotype which may impact on their ability to clear mycobacterial infection. Combined RNA-seq transcriptomic profiling and Reduced Representation Bisulfite Sequencing identified 193 significantly differentially expressed genes and 760 differentially methylated regions (DMRs), between CD4+ T cells from M. bovis infected and healthy cattle. 196 DMRs were located within 10 kb of annotated genes, including GATA3 and RORC, both of which encode transcription factors that promote TH2 and TH17 T helper cell subsets respectively. Gene-specific DNA methylation and gene expression levels for the TNFRSF4 and Interferon-γ genes were significantly negatively correlated suggesting a regulatory relationship. Pathway analysis of DMRs identified enrichment of genes involved in the anti-proliferative TGF-β signaling pathway and TGFB1 expression was significantly increased in peripheral blood leukocytes from TB-infected cattle. This first analysis of the bovine CD4+ T cell methylome suggests that DNA methylation directly contributes to a distinct gene expression signature in CD4+ T cells from cattle infected with M. bovis. Specific methylation changes proximal to key inflammatory gene loci may be critical to the emergence of a non-protective CD4+ T cell response during mycobacterial infection in cattle