scholarly journals An approach for the identification of microRNA with an application to Anopheles gambiae.

2006 ◽  
Vol 53 (2) ◽  
pp. 303-309 ◽  
Author(s):  
Raghunath Chatterjee ◽  
Keya Chaudhuri
Keyword(s):  
Drosophila Melanogaster ◽  
Anopheles Gambiae ◽  
Rna Folding ◽  
Noncoding Rnas ◽  
Phylogenetic Distance ◽  
Loop Structure ◽  
Stem Loop ◽  
Stem Loop Structure ◽  
Related Organism ◽  
Post Transcriptional Regulation

MicroRNAs (miRNAs) are an abundant class of 20-27 nt long noncoding RNAs, involved in post-transcriptional regulation of genes in eukaryotes. These miRNAs are usually highly conserved between the genomes of related organisms and their pre-miRNA transcript, about 60-120 nt long, forms extended stem-loop structure. Keeping these facts in mind miRsearch is developed which relies on searching the homologues of all known miRNAs of one organism in the genome of a related organism allowing few mismatches depending on the phylogenetic distance between them, followed by assessing for the capability of formation of stem-loop structure. The precursor sequences so obtained were then screened through the RNA folding program MFOLD selecting the cut-off values on the basis of known Drosophila melanogaster pre-miRNAs. With this approach, about 91 probable candidate miRNAs along with pre-miRNAs were identified in Anopheles gambiae using known D. melanogaster miRNAs. Out of these, 41 probable miRNAs have 100% similarity with already known D. melanogaster miRNAs and others were found to be at least 85% similar to the miRNAs of various other organisms.

scholarly journals Regulation of Histone H4 Lys16 Acetylation by Predicted Alternative Secondary Structures in roX Noncoding RNAs

2008 ◽  
Vol 28 (16) ◽  
pp. 4952-4962 ◽  
Author(s):  
Seung-Won Park ◽  
Mitzi I. Kuroda ◽  
Yongkyu Park
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Noncoding Rnas ◽  
Loop Structure ◽  
Histone H4 ◽  
Stem Loop ◽  
Functional Conservation ◽  
Stem Loop Structure ◽  
Msl Complex ◽  
H4k16 Acetylation

ABSTRACT Despite differences in size and sequence, the two noncoding roX1 and roX2 RNAs are functionally redundant for dosage compensation of the Drosophila melanogaster male X chromosome. Consistent with functional conservation, we found that roX RNAs of distant Drosophila species could complement D. melanogaster roX mutants despite low homology. Deletion of a conserved predicted stem-loop structure in roX2, containing a short GUb (GUUNUACG box) in its 3′ stem, resulted in a defect in histone H4K16 acetylation on the X chromosome in spite of apparently normal localization of the MSL complex. Two copies of the GUb sequence, newly termed the “roX box,” were functionally redundant in roX2, as mutants in a single roX box had no phenotype, but double mutants showed reduced H4K16 acetylation. Interestingly, mutation of two of three roX boxes in the 3′ end of roX1 RNA also reduced H4K16 acetylation. Finally, fusion of roX1 sequences containing a roX box restored function to a roX2 deletion RNA lacking its cognate roX box. These results support a model in which the functional redundancy between roX1 and roX2 RNAs is based, at least in part, on short GUUNUACG sequences that regulate the activity of the MSL complex.

scholarly journals SAFB2 enables the processing of suboptimal stem-loop structures in clustered primary miRNA transcripts

2019 ◽  
Author(s):  
Katharina Hutter ◽  
Michael Lohmüller ◽  
Almina Jukic ◽  
Felix Eichin ◽  
Seymen Avci ◽  
...  
Keyword(s):  
Noncoding Rnas ◽  
General Mechanism ◽  
List Type ◽  
Loop Structure ◽  
Stem Loop ◽  
Protein Coding ◽  
Mirna Processing ◽  
Small Noncoding Rnas ◽  
Stem Loop Structure ◽  
Attachment Factor

SummaryMicroRNAs (miRNAs) are small noncoding RNAs that post-transcriptionally silence most protein-coding genes in mammals. They are generated from primary transcripts containing single or multiple clustered stem-loop structures that are thought to be recognized and cleaved by the DGCR8/DROSHA Microprocessor complex as independent units. Contrasting this view, we here report an unexpected mode of processing of a bicistronic cluster of the miR-15 family, miR-15a-16-1. We find that the primary miR-15a stem-loop is a poor Microprocessor substrate and is consequently not processed on its own, but that the presence of the neighboring primary miR-16-1 stem-loop on the same transcript can compensate for this deficiency in cis. Using a CRISPR/Cas9 screen, we identify SAFB2 (scaffold attachment factor B2) as an essential co-factor in this miR-16-1-assisted pri-miR-15 cleavage, and describe SAFB2 as a novel accessory protein of DROSHA. Notably, SAFB2-mediated cluster assistance expands to other clustered pri-miRNAs including miR-15b, miR-92a and miR-181b, indicating a general mechanism. Together, our study reveals an unrecognized function of SAFB2 in miRNA processing and suggests a scenario in which SAFB2 enables the binding and processing of suboptimal DGCR8/DROSHA substrates in clustered primary miRNA transcripts.Highlightsthe primary miR-15a stem-loop structure per se is a poor Microprocessor substratecleavage of pri-miR-15a requires the processing of an additional miRNA stem-loop on the same RNAsequential pri-miRNA processing or “cluster assistance” is mediated by SAFB proteinsSAFB2 associates with the Microprocessor

scholarly journals Functional Redundancy Within roX1, a Noncoding RNA Involved in Dosage Compensation in Drosophila melanogaster

Genetics ◽  
2003 ◽  
Vol 164 (3) ◽  
pp. 1003-1014
Author(s):  
Carsten Stuckenholz ◽  
Victoria H Meller ◽  
Mitzi I Kuroda
Keyword(s):  
Drosophila Melanogaster ◽  
X Chromosome ◽  
Noncoding Rna ◽  
Rna Stability ◽  
Loop Structure ◽  
Stem Loop ◽  
Stem Loop Structure ◽  
Expression Of Genes ◽  
Rna Domains ◽  
Rna Disruption

Abstract Drosophila melanogaster males dosage compensate by twofold upregulation of the expression of genes on their single X chromosome. This process requires at least five proteins and two noncoding RNAs, roX1 and roX2, which paint the male X chromosome. We used a deletion analysis to search for functional RNA domains within roX1, assaying RNA stability, targeting of the MSL proteins to the X, and rescue of male viability in a roX1-  roX2- mutant background. We found that deletion of 10% segments of the RNA did not dramatically reduce function in most cases, suggesting extensive internal redundancy. The 3′ 600 nt of roX1 were most sensitive to mutations, affecting proper localization and 3′ processing of the RNA. Disruption of an inverted repeat predicted to form a stem-loop structure was found partially responsible for the defects observed.

scholarly journals The perplexities of ZC3H12A self-mRNA regulation

2016 ◽  
Vol 63 (3) ◽  
Author(s):  
Mateusz Wawro ◽  
Jakub Kochan ◽  
Aneta Kasza
Keyword(s):  
Gene Expression ◽  
Biological Activity ◽  
Transcriptional Regulation ◽  
Untranslated Region ◽  
Regulation Of Gene Expression ◽  
Loop Structure ◽  
Stem Loop ◽  
Mrna Regulation ◽  
Stem Loop Structure ◽  
Post Transcriptional Regulation

The mechanisms regulating transcripts turnover are key processes in the regulation of gene expression. The list of proteins involved in mRNAs degradation is still growing, however, the details of RNase-mRNAs interaction are not fully understood. ZC3H12A is a recently discovered inflammation-related RNase engaged in the control of proinflammatory cytokines transcripts turnover. ZC3H12A regulates also its own transcript half-live. We studied the details of this regulation. Our results confirm the importance of the 3’UTR in ZC3H12A-dependent ZC3H12A mRNA degradations. We compared mouse and human stem‑loop structures present in this region and discovered that human conserved stem-loop structure is not sufficient for ZC3H12A-dependent degradation. However, this structure is important for ZC3H12A mRNA post-transcriptional regulation. Our studies emphasize the importance of surroundings of the identified stem-loop structure for its biological activity. Removing of this region together with stem-loop structure greatly inhibits ZC3H12A regulation of the investigated 3’-untranslated region (3’UTR).

968: Gelsolin Gene Silencing Involving Unusual Chromatin Structures and a Novel Stem Loop Structure of the Promoter Region in Human Bladder Cancer

2004 ◽  
Vol 171 (4S) ◽  
pp. 256-257
Author(s):  
Kazunori Haga ◽  
Ataru Sazawa ◽  
Toru Harabayashi ◽  
Nobuo Shinohara ◽  
Minoru Nomoto ◽  
...  
Keyword(s):  
Bladder Cancer ◽  
Gene Silencing ◽  
Promoter Region ◽  
Loop Structure ◽  
Human Bladder Cancer ◽  
Human Bladder ◽  
Stem Loop ◽  
Stem Loop Structure

Detection and sequence analysis of an imperfect stem-loop structure in cis activating gene element from SV40PolyA

2011 ◽  
Vol 33 (4) ◽  
pp. 337-346
Author(s):  
Hong-Gang WANG ◽  
Huan MA ◽  
Zhu LI ◽  
Bin ZHANG ◽  
Xiang-Yang JING ◽  
...  
Keyword(s):  
Sequence Analysis ◽  
Loop Structure ◽  
Stem Loop ◽  
Stem Loop Structure ◽  
In Cis ◽  
Gene Element

scholarly journals Locking up the AS1411 Aptamer with a Flanking Duplex: Towards an Improved Nucleolin-Targeting

2021 ◽  
Vol 14 (2) ◽  
pp. 121
Author(s):  
André Miranda ◽  
Tiago Santos ◽  
Eric Largy ◽  
Carla Cruz
Keyword(s):  
Loop Structure ◽  
Binding Properties ◽  
Stem Loop ◽  
Affinity Ligand ◽  
Stem Loop Structure ◽  
Topology Maintenance ◽  
G Quadruplex ◽  
Dimeric Form ◽  
Biophysical Techniques ◽  
Melting Experiments

We have designed AS1411-N6, a derivative of the nucleolin (NCL)-binding aptamer AS1411, by adding six nucleotides to the 5′-end that are complementary to nucleotides at the 3′-end forcing it into a stem-loop structure. We evaluated by several biophysical techniques if AS1411-N6 can adopt one or more conformations, one of which allows NCL binding. We found a decrease of polymorphism of G-quadruplex (G4)-forming sequences comparing to AS1411 and the G4 formation in presence of K+ promotes the duplex folding. We also studied the binding properties of ligands TMPyP4, PhenDC3, PDS, 360A, and BRACO-19 in terms of stability, binding, topology maintenance of AS1411-N6, and NCL recognition. The melting experiments revealed promising stabilizer effects of PhenDC3, 360A, and TMPyP4, and the affinity calculations showed that 360A is the most prominent affinity ligand for AS1411-N6 and AS1411. The affinity determined between AS1411-N6 and NCL denoting a strong interaction and complex formation was assessed by PAGE in which the electrophoretic profile of AS1411-N6 showed bands of the dimeric form in the presence of the ligands and NCL.

scholarly journals Role of a Stem-Loop Structure inHelicobacter pylori cagATranscript Stability

2018 ◽  
Vol 87 (2) ◽  
Author(s):  
John T. Loh ◽  
Aung Soe Lin ◽  
Amber C. Beckett ◽  
Mark S. McClain ◽  
Timothy L. Cover
Keyword(s):  
Steady State ◽  
Untranslated Region ◽  
Loop Structure ◽  
Stem Loop ◽  
Content Type ◽  
Transcript Stability ◽  
Protein Levels ◽  
Caga Protein ◽  
Stem Loop Structure ◽  
Steady State Levels

ABSTRACTHelicobacter pyloriCagA is a secreted effector protein that contributes to gastric carcinogenesis. Previous studies showed that there is variation amongH. pyloristrains in the steady-state levels of CagA and that a strain-specific motif downstream of thecagAtranscriptional start site (the +59 motif) is associated with both high levels of CagA and premalignant gastric histology. ThecagA5′ untranslated region contains a predicted stem-loop-forming structure adjacent to the +59 motif. In the current study, we investigated the effect of the +59 motif and the adjacent stem-loop oncagAtranscript levels andcagAmRNA stability. Using site-directed mutagenesis, we found that mutations predicted to disrupt the stem-loop structure resulted in decreased steady-state levels of both thecagAtranscript and the CagA protein. Additionally, these mutations resulted in a decreasedcagAmRNA half-life. Mutagenesis of the +59 motif without altering the stem-loop structure resulted in reduced steady-statecagAtranscript and CagA protein levels but did not affectcagAtranscript stability.cagAtranscript stability was not affected by increased sodium chloride concentrations, an environmental factor known to augmentcagAtranscript levels and CagA protein levels. These results indicate that both a predicted stem-loop structure and a strain-specific +59 motif in thecagA5′ untranslated region influence the levels ofcagAexpression.

scholarly journals Mechanism of Rep-Mediated Adeno-Associated Virus Origin Nicking

2000 ◽  
Vol 74 (17) ◽  
pp. 7762-7771 ◽  
Author(s):  
J. Rodney Brister ◽  
Nicholas Muzyczka
Keyword(s):  
Specific Activity ◽  
Dna Helicase ◽  
Loop Structure ◽  
Stem Loop ◽  
Adeno Associated Virus ◽  
Stem Loop Structure ◽  
Virus Origin ◽  
Rep Proteins ◽  
Sequence Elements ◽  
Origin Function

ABSTRACT The single-stranded adeno-associated virus type 2 (AAV) genome is flanked by terminal repeats (TRs) that fold back on themselves to form hairpinned structures. During AAV DNA replication, the TRs are nicked by the virus-encoded Rep proteins at the terminal resolution site (trs). This origin function apparently requires three sequence elements, the Rep binding element (RBE), a small palindrome that comprises a single tip of an internal hairpin within the TR (RBE′), and the trs. Previously, we determined the sequences at the trs required for Rep-mediated cleavage and demonstrated that the trs endonuclease reaction occurs in two discrete steps. In the first step, the Rep DNA helicase activity unwinds the TR, thereby extruding a stem-loop structure at thetrs. In the second step, Rep transesterification activity cleaves the trs. Here we investigate the contribution of the RBE and RBE′ during this process. Our data indicate that Rep is tethered to the RBE in a specific orientation duringtrs nicking. This orientation appears to align Rep on the AAV TR, allowing specific nucleotide contacts with the RBE′ and directing nicking to the trs. Accordingly, alterations in the polarity or position of the RBE relative to the trsgreatly inhibit Rep nicking. Substitutions within the RBE′ also reduce Rep specific activity, but to a lesser extent. Interestingly, Rep interactions with the RBE and RBE′ during nicking seem to be functionally distinct. Rep contacts with the RBE appear necessary for both the DNA helicase and trs cleavage steps of the endonuclease reaction. On the other hand, RBE′ contacts seem to be required primarily for TR unwinding and formation of thetrs stem-loop structure, not cleavage. Together, these results suggest a model of Rep interaction with the AAV TR during origin nicking through a tripartite cleavage signal comprised of the RBE, the RBE′, and the trs.

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