Article

RNA Polymerase II Binding Patterns Reveal Genomic Regions Involved in MicroRNA Gene Regulation

University of Calgary, Canada
PLoS ONE (Impact Factor: 3.53). 11/2010; 5(11):e13798. DOI: 10.1371/journal.pone.0013798
Source: PubMed

ABSTRACT MicroRNAs are small non-coding RNAs involved in post-transcriptional regulation of gene expression. Due to the poor annotation of primary microRNA (pri-microRNA) transcripts, the precise location of promoter regions driving expression of many microRNA genes is enigmatic. This deficiency hinders our understanding of microRNA-mediated regulatory networks. In this study, we develop a computational approach to identify the promoter region and transcription start site (TSS) of pri-microRNAs actively transcribed using genome-wide RNA Polymerase II (RPol II) binding patterns derived from ChIP-seq data. Based upon the assumption that the distribution of RPol II binding patterns around the TSS of microRNA and protein coding genes are similar, we designed a statistical model to mimic RPol II binding patterns around the TSS of highly expressed, well-annotated promoter regions of protein coding genes. We used this model to systematically scan the regions upstream of all intergenic microRNAs for RPol II binding patterns similar to those of TSS from protein coding genes. We validated our findings by examining the conservation, CpG content, and activating histone marks in the identified promoter regions. We applied our model to assess changes in microRNA transcription in steroid hormone-treated breast cancer cells. The results demonstrate many microRNA genes have lost hormone-dependent regulation in tamoxifen-resistant breast cancer cells. MicroRNA promoter identification based upon RPol II binding patterns provides important temporal and spatial measurements regarding the initiation of transcription, and therefore allows comparison of transcription activities between different conditions, such as normal and disease states.

0 Bookmarks
 · 
110 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In the cell nucleus, each chromosome is confined to a chromosome territory. This spatial organization of chromosomes plays a crucial role in gene regulation and genome stability. An additional level of organization has been discovered at the chromosome scale: the spatial segregation into open and closed chromatins to form two genome-wide compartments. Although considerable progress has been made in our knowledge of chromatin organization, a fundamental issue remains the understanding of its dynamics, especially in cancer. To address this issue, we performed genome-wide mapping of chromatin interactions (Hi-C) over the time after estrogen stimulation of breast cancer cells. To biologically interpret these interactions, we integrated with estrogen receptor (ER α ) binding events, gene expression and epi
    PLoS ONE 12/2014; 9(12):e113354. DOI:10.1371/journal.pone.0113354 · 3.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Background. The aim of this study was to profile TLR4/NF-κB-responsive microRNAs (miRNAs) and their potential target genes in the skeletal muscles of mice following ischemia-reperfusion injury. Methods. Thigh skeletal muscles of C57BL/6, Tlr4 (-/-), and NF-κB (-/-) mice isolated based on femoral artery perfusion were subjected to ischemia for 2 h and reperfusion for 0 h, 4 h, 1 d, and 7 d. The muscle specimens were analyzed with miRNA arrays. Immunoprecipitation with an argonaute 2- (Ago2-) specific monoclonal antibody followed by whole genome microarray was performed to identify mRNA associated with the RNA-silencing machinery. The potential targets of each upregulated miRNA were identified by combined analysis involving the bioinformatics algorithm miRanda and whole genome expression. Results. Three TLR4/NF-κB-responsive miRNAs (miR-15a, miR-744, and miR-1196) were significantly upregulated in the muscles following ischemia-reperfusion injury. The combined in silico and whole genome microarray approaches identified 5, 4, and 20 potential target genes for miR-15a, miR-744, and miR-1196, respectively. Among the 3 genes (Zbed4, Lrsam1, and Ddx21) regulated by at least 2 of the 3 upregulated miRNAs, Lrsam1 and Ddx21 are known to be associated with the innate immunity pathway. Conclusions. This study profiled TLR4/NF-κB-responsive miRNAs and their potential target genes in mouse skeletal muscle subjected to ischemia-reperfusion injury.
    BioMed Research International 01/2015; 2015:410721. DOI:10.1155/2015/410721 · 2.71 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: MicroRNAs (miRNAs) are short (22 nucleotides), single-stranded, non-coding RNAs that form complimentary base-pairs with the 3' untranslated region of target mRNAs within the RNA-induced silencing complex (RISC) and block translation and/or stimulate mRNA transcript degradation. The non-coding miRBase (release 21, June 2014) reports that human genome contains ~2,588 mature miRNAs which regulate ~ 60% of human protein-coding mRNAs. Dysregulation of miRNA expression has been implicated in estrogen-related diseases including breast and endometrial cancers. The mechanism for estrogen regulation of miRNA expression and the role of estrogen-regulated miRNAs in normal homeostasis, reproduction, lactation, and in cancer is an area of great research and clinical interest. Estrogens regulate miRNAs transcription through estrogen receptors α and β in a tissue-specific and cell-dependent manner. This review focuses primary on the regulation of miRNA expression by ligand-activated ERs and their bona fide gene targets and includes miRNAs regulation by tamoxifen and endocrine disrupting chemicals (EDCs) in breast cancer and cell lines. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
    Molecular and Cellular Endocrinology 02/2015; DOI:10.1016/j.mce.2015.01.035 · 4.24 Impact Factor

Full-text (2 Sources)

Download
48 Downloads
Available from
May 27, 2014