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1.
Curr Opin Struct Biol ; 88: 102908, 2024 Aug 14.
Artículo en Inglés | MEDLINE | ID: mdl-39146886

RESUMEN

RNA's ability to form and interconvert between multiple secondary and tertiary structures is critical to its functional versatility and the traditional view of RNA structures as static entities has shifted towards understanding them as dynamic conformational ensembles. In this review we discuss RNA structural ensembles and their dynamics, highlighting the concept of conformational energy landscapes as a unifying framework for understanding RNA processes such as folding, misfolding, conformational changes, and complex formation. Ongoing advancements in cryo-electron microscopy and chemical probing techniques are significantly enhancing our ability to investigate multiple structures adopted by conformationally dynamic RNAs, while traditional methods such as nuclear magnetic resonance spectroscopy continue to play a crucial role in providing high-resolution, quantitative spatial and temporal information. We discuss how these methods, when used synergistically, can provide a comprehensive understanding of RNA conformational ensembles, offering new insights into their regulatory functions.

2.
J Cell Biol ; 223(7)2024 07 01.
Artículo en Inglés | MEDLINE | ID: mdl-38625077

RESUMEN

The centromere is a fundamental higher-order structure in chromosomes ensuring their faithful segregation upon cell division. Centromeric transcripts have been described in several species and suggested to participate in centromere function. However, low sequence conservation of centromeric repeats appears inconsistent with a role in recruiting highly conserved centromeric proteins. Here, we hypothesized that centromeric transcripts may function through a secondary structure rather than sequence conservation. Using mouse embryonic stem cells (ESCs), we show that an imbalance in the levels of forward or reverse minor satellite (MinSat) transcripts leads to severe chromosome segregation defects. We further show that MinSat RNA adopts a stem-loop secondary structure, which is conserved in human α-satellite transcripts. We identify an RNA binding region in CENPC and demonstrate that MinSat transcripts function through the structured region of the RNA. Importantly, mutants that disrupt MinSat secondary structure do not cause segregation defects. We propose that the conserved role of centromeric transcripts relies on their secondary RNA structure.


Asunto(s)
Segregación Cromosómica , Satélite de ARN , Animales , Humanos , Ratones , División Celular , Células Madre Embrionarias de Ratones , Satélite de ARN/química , Satélite de ARN/metabolismo , Centrómero/metabolismo
3.
J Biol Chem ; 300(6): 107317, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38677514

RESUMEN

It has become increasingly evident that the structures RNAs adopt are conformationally dynamic; the various structured states that RNAs sample govern their interactions with other nucleic acids, proteins, and ligands to regulate a myriad of biological processes. Although several biophysical approaches have been developed and used to study the dynamic landscape of structured RNAs, technical limitations have limited their application to all classes of RNA due to variable size and flexibility. Recent advances combining chemical probing experiments with next-generation- and direct sequencing have emerged as an alternative approach to exploring the conformational dynamics of RNA. In this review, we provide a methodological overview of the sequencing-based techniques used to study RNA conformational dynamics. We discuss how different techniques have enabled us to better understand the propensity of RNAs from a variety of different classes to sample multiple conformational states. Finally, we present examples of the ways these techniques have reshaped how we think about RNA structure.


Asunto(s)
Secuenciación de Nucleótidos de Alto Rendimiento , Conformación de Ácido Nucleico , ARN , ARN/química , ARN/metabolismo , Secuenciación de Nucleótidos de Alto Rendimiento/métodos , Nanoporos , Humanos , Análisis de Secuencia de ARN/métodos
4.
Nucleic Acids Res ; 52(11): 6441-6458, 2024 Jun 24.
Artículo en Inglés | MEDLINE | ID: mdl-38499483

RESUMEN

Coronaviruses modify their single-stranded RNA genome with a methylated cap during replication to mimic the eukaryotic mRNAs. The capping process is initiated by several nonstructural proteins (nsp) encoded in the viral genome. The methylation is performed by two methyltransferases, nsp14 and nsp16, while nsp10 acts as a co-factor to both. Additionally, nsp14 carries an exonuclease domain which operates in the proofreading system during RNA replication of the viral genome. Both nsp14 and nsp16 were reported to independently bind nsp10, but the available structural information suggests that the concomitant interaction between these three proteins would be impossible due to steric clashes. Here, we show that nsp14, nsp10, and nsp16 can form a heterotrimer complex upon significant allosteric change. This interaction is expected to encourage the formation of mature capped viral mRNA, modulating nsp14's exonuclease activity, and protecting the viral RNA. Our findings show that nsp14 is amenable to allosteric regulation and may serve as a novel target for therapeutic approaches.


Asunto(s)
Metiltransferasas , ARN Viral , SARS-CoV-2 , Proteínas no Estructurales Virales , SARS-CoV-2/genética , SARS-CoV-2/metabolismo , Proteínas no Estructurales Virales/metabolismo , Proteínas no Estructurales Virales/genética , Proteínas no Estructurales Virales/química , Metiltransferasas/metabolismo , Metiltransferasas/genética , Metiltransferasas/química , Metilación , ARN Viral/metabolismo , ARN Viral/química , ARN Viral/genética , Exorribonucleasas/metabolismo , Exorribonucleasas/genética , Humanos , Unión Proteica , Caperuzas de ARN/metabolismo , Caperuzas de ARN/genética , Regulación Alostérica , COVID-19/virología , COVID-19/genética , Multimerización de Proteína , Replicación Viral/genética , ARN Mensajero/metabolismo , ARN Mensajero/genética , ARN Mensajero/química , Proteínas Reguladoras y Accesorias Virales
5.
J Chem Theory Comput ; 19(12): 3672-3685, 2023 Jun 27.
Artículo en Inglés | MEDLINE | ID: mdl-37288967

RESUMEN

Chemical probing experiments such as SHAPE are routinely used to probe RNA molecules. In this work, we use atomistic molecular dynamics simulations to test the hypothesis that binding of RNA with SHAPE reagents is affected by cooperative effects leading to an observed reactivity that is dependent on the reagent concentration. We develop a general technique that enables the calculation of the affinity for arbitrary molecules as a function of their concentration in the grand-canonical ensemble. Our simulations of an RNA structural motif suggest that, at the concentration typically used in SHAPE experiments, cooperative binding would lead to a measurable concentration-dependent reactivity. We also provide a qualitative validation of this statement by analyzing a new set of experiments collected at different reagent concentrations.


Asunto(s)
Simulación de Dinámica Molecular , ARN , Conformación de Ácido Nucleico , ARN/química , Motivos de Nucleótidos
6.
Sci Adv ; 8(31): eabp9153, 2022 08 05.
Artículo en Inglés | MEDLINE | ID: mdl-35921415

RESUMEN

Alternative splicing plays key roles for cell type-specific regulation of protein function. It is controlled by cis-regulatory RNA elements that are recognized by RNA binding proteins (RBPs). The MALT1 paracaspase is a key factor of signaling pathways that mediate innate and adaptive immune responses. Alternative splicing of MALT1 is critical for controlling optimal T cell activation. We demonstrate that MALT1 splicing depends on RNA structural elements that sequester the splice sites of the alternatively spliced exon7. The RBPs hnRNP U and hnRNP L bind competitively to stem-loop RNA structures that involve the 5' and 3' splice sites flanking exon7. While hnRNP U stabilizes RNA stem-loop conformations that maintain exon7 skipping, hnRNP L disrupts these RNA elements to facilitate recruitment of the essential splicing factor U2AF2, thereby promoting exon7 inclusion. Our data represent a paradigm for the control of splice site selection by differential RBP binding and modulation of pre-mRNA structure.


Asunto(s)
Ribonucleoproteína Heterogénea-Nuclear Grupo L , Precursores del ARN , Empalme Alternativo , Sitios de Unión , Exones , Ribonucleoproteína Heterogénea-Nuclear Grupo L/genética , Ribonucleoproteína Heterogénea-Nuclear Grupo L/metabolismo , Ribonucleoproteína Heterogénea-Nuclear Grupo U/genética , Ribonucleoproteína Heterogénea-Nuclear Grupo U/metabolismo , Ribonucleoproteínas Nucleares Heterogéneas/genética , Ribonucleoproteínas Nucleares Heterogéneas/metabolismo , Proteína 1 de la Translocación del Linfoma del Tejido Linfático Asociado a Mucosas/genética , Proteína 1 de la Translocación del Linfoma del Tejido Linfático Asociado a Mucosas/metabolismo , Precursores del ARN/genética , Sitios de Empalme de ARN , Proteínas de Unión al ARN/genética , Proteínas de Unión al ARN/metabolismo
7.
Sci Rep ; 12(1): 9593, 2022 06 10.
Artículo en Inglés | MEDLINE | ID: mdl-35688849

RESUMEN

The replication complex (RC) of SARS-CoV-2 was recently shown to be one of the fastest RNA-dependent RNA polymerases of any known coronavirus. With this rapid elongation, the RC is more prone to incorporate mismatches during elongation, resulting in a highly variable genomic sequence. Such mutations render the design of viral protein targets difficult, as drugs optimized for a given viral protein sequence can quickly become inefficient as the genomic sequence evolves. Here, we use biochemical experiments to characterize features of RNA template recognition and elongation fidelity of the SARS-CoV-2 RdRp, and the role of the exonuclease, nsp14. Our study highlights the 2'OH group of the RNA ribose as a critical component for RdRp template recognition and elongation. We show that RdRp fidelity is reduced in the presence of the 3' deoxy-terminator nucleotide 3'dATP, which promotes the incorporation of mismatched nucleotides (leading to U:C, U:G, U:U, C:U, and A:C base pairs). We find that the nsp10-nsp14 heterodimer is unable to degrade RNA products lacking free 2'OH or 3'OH ribose groups. Our results suggest the potential use of 3' deoxy-terminator nucleotides in RNA-derived oligonucleotide inhibitors as antivirals against SARS-CoV-2.


Asunto(s)
COVID-19 , SARS-CoV-2 , Antivirales/química , Antivirales/farmacología , Humanos , Nucleótidos/farmacología , ARN Viral/genética , ARN Viral/metabolismo , ARN Polimerasa Dependiente del ARN/genética , Ribosa , SARS-CoV-2/genética , Proteínas no Estructurales Virales/metabolismo , Proteínas Virales/genética , Proteínas Virales/farmacología , Replicación Viral/genética
8.
J Mol Biol ; 434(18): 167705, 2022 09 30.
Artículo en Inglés | MEDLINE | ID: mdl-35760371

RESUMEN

MicroRNAs (miRNAs) are small, noncoding RNAs that mediate post-transcriptional downregulation of specific target genes. These transcripts are the products of a two-step processing pathway; primary miRNAs (pri-miRNAs) are processed by Drosha into individual precursor miRNA (pre-miRNA) hairpins, which are subsequently processed by Dicer into mature miRNAs. Single nucleotide polymorphisms (SNPs) that occur in pri-miRNAs, pre-miRNAs and mature miRNAs have been shown to affect the processing of specific target genes by modulating Drosha and Dicer processing or interactions with RNA binding proteins (RBPs). Using NMR and single-molecule optical tweezer experiments, we have investigated the conformational effects of a cancer-linked G/A mutation in the terminal loop of pri-miR-30c RNA, and how this influences binding by the SRSF3 and hnRNP A1 RBPs, which are implicated in its processing. Our results reveal that the wildtype and G/A variant pri-miR-30c RNAs adopt very similar elongated stem-loop structures, both of which are bound by SRSF3. However, while both wildtype and G/A pri-miR-30c RNAs can form dimeric kissing hairpin structures, the G to A mutation results in partial destabilization of the dimer in the variant transcript. This promotes recognition and binding by hnRNP A1, an RBP that enhances pri-miR-30c processing. Our data provide structural insight into the conformational effects of a G/A mutation in pri-miR-30c RNA and how this could affect processing and promote cancer.


Asunto(s)
Ribonucleoproteína Nuclear Heterogénea A1 , MicroARNs , Neoplasias , Procesamiento Postranscripcional del ARN , Ribonucleoproteína Nuclear Heterogénea A1/metabolismo , Humanos , MicroARNs/química , MicroARNs/genética , MicroARNs/metabolismo , Mutación , Neoplasias/genética , Resonancia Magnética Nuclear Biomolecular , Conformación de Ácido Nucleico , Pinzas Ópticas , Proteínas de Unión al ARN/metabolismo , Ribonucleasa III/genética , Factores de Empalme Serina-Arginina/metabolismo , Imagen Individual de Molécula
9.
Nucleic Acids Res ; 50(4): 2350-2362, 2022 02 28.
Artículo en Inglés | MEDLINE | ID: mdl-35166835

RESUMEN

The A-repeat region of the lncRNA Xist is critical for X inactivation and harbors several N6-methyladenosine (m6A) modifications. How the m6A modification affects the conformation of the conserved AUCG tetraloop hairpin of the A-repeats and how it can be recognized by the YTHDC1 reader protein is unknown. Here, we report the NMR solution structure of the (m6A)UCG hairpin, which reveals that the m6A base extends 5' stacking of the A-form helical stem, resembling the unmethylated AUCG tetraloop. A crystal structure of YTHDC1 bound to the (m6A)UCG tetraloop shows that the (m6A)UC nucleotides are recognized by the YTH domain of YTHDC1 in a single-stranded conformation. The m6A base inserts into the aromatic cage and the U and C bases interact with a flanking charged surface region, resembling the recognition of single-stranded m6A RNA ligands. Notably, NMR and fluorescence quenching experiments show that the binding requires local unfolding of the upper stem region of the (m6A)UCG hairpin. Our data show that m6A can be readily accommodated in hairpin loop regions, but recognition by YTH readers requires local unfolding of flanking stem regions. This suggests how m6A modifications may regulate lncRNA function by modulating RNA structure.


Asunto(s)
Adenosina/análogos & derivados , Factores de Empalme de ARN , ARN Largo no Codificante , Adenosina/química , Adenosina/metabolismo , Factores de Empalme de ARN/metabolismo , ARN Largo no Codificante/química , ARN Largo no Codificante/genética , Inactivación del Cromosoma X
10.
Circ Res ; 130(1): 67-79, 2022 01 07.
Artículo en Inglés | MEDLINE | ID: mdl-34789007

RESUMEN

BACKGROUND: Circular RNAs (circRNAs) are generated by back splicing of mostly mRNAs and are gaining increasing attention as a novel class of regulatory RNAs that control various cellular functions. However, their physiological roles and functional conservation in vivo are rarely addressed, given the inherent challenges of their genetic inactivation. Here, we aimed to identify locus conserved circRNAs in mice and humans, which can be genetically deleted due to retained intronic elements not contained in the mRNA host gene to eventually address functional conservation. METHODS AND RESULTS: Combining published endothelial RNA-sequencing data sets with circRNAs of the circATLAS databank, we identified locus-conserved circRNA retaining intronic elements between mice and humans. CRISPR/Cas9 mediated genetic depletion of the top expressed circRNA cZfp292 resulted in an altered endothelial morphology and aberrant flow alignment in the aorta in vivo. Consistently, depletion of cZNF292 in endothelial cells in vitro abolished laminar flow-induced alterations in cell orientation, paxillin localization and focal adhesion organization. Mechanistically, we identified the protein SDOS (syndesmos) to specifically interact with cZNF292 in endothelial cells by RNA-affinity purification and subsequent mass spectrometry analysis. Silencing of SDOS or its protein binding partner Syndecan-4, or mutation of the SDOS-cZNF292 binding site, prevented laminar flow-induced cytoskeletal reorganization thereby recapitulating cZfp292 knockout phenotypes. CONCLUSIONS: Together, our data reveal a hitherto unknown role of cZNF292/cZfp292 in endothelial flow responses, which influences endothelial shape.


Asunto(s)
Proteínas de Unión al ADN , Células Endoteliales , Endotelio Vascular , ARN Circular , Factores de Transcripción , Animales , Humanos , Ratones , Circulación Sanguínea , Proteínas de Unión al ADN/genética , Células Endoteliales/metabolismo , Células Endoteliales/fisiología , Endotelio Vascular/citología , Endotelio Vascular/fisiología , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Ratones Endogámicos C57BL , Unión Proteica , ARN Circular/genética , ARN Circular/metabolismo , Sindecano-4/metabolismo , Factores de Transcripción/genética
11.
Appl Nurs Res ; 62: 151504, 2021 12.
Artículo en Inglés | MEDLINE | ID: mdl-34815000

RESUMEN

This secondary data analysis study aimed to (1) investigate the use of two sense-based parameters (movement and sleep hours) as predictors of chronic pain when controlling for patient demographics and depression, and (2) identify a classification model with accuracy in predicting chronic pain. Data collected by Oregon Health & Science University between March 2018 and December 2019 under the Collaborative Aging Research Using Technology Initiative were analyzed in two stages. Data were collected by sensor technologies and questionnaires from older adults living independently or with a partner in the community. In Stage 1, regression models were employed to determine unique sensor-based behavioral predictors of pain. These sensor-based parameters were used to create a classification model to predict the weekly recalled pain intensity and interference level using a deep neural network model, a machine learning approach, in Stage 2. Daily step count was a unique predictor for both pain intensity (75% Accuracy, F1 = 0.58) and pain interference (82% Accuracy, F1 = 0.59). The developed classification model performed well in this dataset with acceptable accuracy scores. This study demonstrated that machine learning technique can be used to identify the relationship between patients' pain and the risk factors.


Asunto(s)
Dolor Crónico , Anciano , Algoritmos , Dolor Crónico/diagnóstico , Humanos , Aprendizaje Automático , Factores de Riesgo , Encuestas y Cuestionarios
12.
EMBO Rep ; 22(6): e49568, 2021 06 04.
Artículo en Inglés | MEDLINE | ID: mdl-33969602

RESUMEN

Hepatitis B virus (HBV) persists by depositing a covalently closed circular DNA (cccDNA) in the nucleus of infected cells that cannot be targeted by available antivirals. Interferons can diminish HBV cccDNA via APOBEC3-mediated deamination. Here, we show that overexpression of APOBEC3A alone is not sufficient to reduce HBV cccDNA that requires additional treatment of cells with interferon indicating involvement of an interferon-stimulated gene (ISG) in cccDNA degradation. Transcriptome analyses identify ISG20 as the only type I and II interferon-induced, nuclear protein with annotated nuclease activity. ISG20 localizes to nucleoli of interferon-stimulated hepatocytes and is enriched on deoxyuridine-containing single-stranded DNA that mimics transcriptionally active, APOBEC3A-deaminated HBV DNA. ISG20 expression is detected in human livers in acute, self-limiting but not in chronic hepatitis B. ISG20 depletion mitigates the interferon-induced loss of cccDNA, and co-expression with APOBEC3A is sufficient to diminish cccDNA. In conclusion, non-cytolytic HBV cccDNA decline requires the concerted action of a deaminase and a nuclease. Our findings highlight that ISGs may cooperate in their antiviral activity that may be explored for therapeutic targeting.


Asunto(s)
ADN Circular , Virus de la Hepatitis B , Antivirales/farmacología , Citidina Desaminasa , ADN Circular/genética , ADN Viral/genética , ADN Viral/farmacología , Exorribonucleasas , Virus de la Hepatitis B/genética , Humanos , Interferones , Proteínas , Replicación Viral
13.
J Clin Invest ; 131(10)2021 05 17.
Artículo en Inglés | MEDLINE | ID: mdl-33784254

RESUMEN

Vascular stability and tone are maintained by contractile smooth muscle cells (VSMCs). However, injury-induced growth factors stimulate a contractile-synthetic phenotypic modulation which increases susceptibility to abdominal aortic aneurysm (AAA). As a regulator of embryonic VSMC differentiation, we hypothesized that Thymosin ß4 (Tß4) may function to maintain healthy vasculature throughout postnatal life. This was supported by the identification of an interaction with low density lipoprotein receptor related protein 1 (LRP1), an endocytic regulator of platelet-derived growth factor BB (PDGF-BB) signaling and VSMC proliferation. LRP1 variants have been implicated by genome-wide association studies with risk of AAA and other arterial diseases. Tß4-null mice displayed aortic VSMC and elastin defects that phenocopy those of LRP1 mutants, and their compromised vascular integrity predisposed them to Angiotensin II-induced aneurysm formation. Aneurysmal vessels were characterized by enhanced VSMC phenotypic modulation and augmented PDGFR-ß signaling. In vitro, enhanced sensitivity to PDGF-BB upon loss of Tß4 was associated with dysregulated endocytosis, with increased recycling and reduced lysosomal targeting of LRP1-PDGFR-ß. Accordingly, the exacerbated aneurysmal phenotype in Tß4-null mice was rescued upon treatment with the PDGFR-ß antagonist Imatinib. Our study identifies Tß4 as a key regulator of LRP1 for maintaining vascular health, and provides insights into the mechanisms of growth factor-controlled VSMC phenotypic modulation underlying aortic disease progression.


Asunto(s)
Aneurisma de la Aorta Abdominal/prevención & control , Músculo Liso Vascular/metabolismo , Miocitos del Músculo Liso/metabolismo , Transducción de Señal/efectos de los fármacos , Timosina/farmacología , Angiotensina II/efectos adversos , Angiotensina II/farmacología , Animales , Aneurisma de la Aorta Abdominal/inducido químicamente , Aneurisma de la Aorta Abdominal/genética , Aneurisma de la Aorta Abdominal/metabolismo , Becaplermina/genética , Becaplermina/metabolismo , Proteína 1 Relacionada con Receptor de Lipoproteína de Baja Densidad/genética , Proteína 1 Relacionada con Receptor de Lipoproteína de Baja Densidad/metabolismo , Masculino , Ratones , Ratones Noqueados , Receptor beta de Factor de Crecimiento Derivado de Plaquetas/genética , Receptor beta de Factor de Crecimiento Derivado de Plaquetas/metabolismo , Transducción de Señal/genética , Timosina/genética , Timosina/metabolismo
14.
J Am Acad Audiol ; 32(1): 3-9, 2021 01.
Artículo en Inglés | MEDLINE | ID: mdl-33588511

RESUMEN

BACKGROUND: Many apps have been developed for users to screen their hearing in their own home. The purpose of this study was to investigate the validity and efficiency of a self-assessed acceptable noise level (ANL) in comparison to the traditional ANL measurements. RESEARCH DESIGN: A within-subject repeated measures research design was utilized. DATA COLLECTION AND ANALYSIS: Sixty-two adults with normal hearing were recruited from Auburn University and the surrounding community. ANLs were measured utilizing the traditional measurement as well as the self-assessed ANL via the Unitron uHear app. RESULTS: Within-subject repeated measures of variance revealed no significant differences between traditional ANL measurements and self-assessed ANL measurements. Significant differences were found for time required for testing in each condition, revealing self-assessed testing to be significantly faster. CONCLUSION: The self-assessed ANL measurement via the Unitron uHear app is a valid and efficient measurement of ANL in adults with normal hearing.


Asunto(s)
Audífonos , Pérdida Auditiva Sensorineural , Percepción del Habla , Adulto , Audición , Humanos , Ruido
15.
RNA ; 26(9): 1234-1246, 2020 09.
Artículo en Inglés | MEDLINE | ID: mdl-32457084

RESUMEN

The wide prevalence and regulated expression of long noncoding RNAs (lncRNAs) highlight their functional roles, but the molecular basis for their activities and structure-function relationships remains to be investigated, with few exceptions. Among the relatively few lncRNAs conserved over significant evolutionary distances is the long intergenic noncoding RNA (lincRNA) Cyrano (orthologous to human OIP5-AS1), which contains a region of 300 highly conserved nucleotides within tetrapods, which in turn contains a functional stretch of 26 nt of deep conservation. This region binds to and facilitates the degradation of the microRNA miR-7, a short ncRNA with multiple cellular functions, including modulation of oncogenic expression. We probed the secondary structure of Cyrano in vitro and in cells using chemical and enzymatic probing, and validated the results using comparative sequence analysis. At the center of the functional core of Cyrano is a cloverleaf structure maintained over the >400 million years of divergent evolution that separates fish and primates. This strikingly conserved motif provides interaction sites for several RNA-binding proteins and masks a conserved recognition site for miR-7. Conservation in this region strongly suggests that the function of Cyrano depends on the formation of this RNA structure, which could modulate the rate and efficiency of degradation of miR-7.


Asunto(s)
Secuencia Conservada/genética , ARN Largo no Codificante/genética , Proteínas de Unión al ARN/genética , Animales , Humanos , Ratones , MicroARNs/genética , Primates/genética , ARN Mensajero/genética , ARN no Traducido/genética , Pez Cebra
16.
NAR Genom Bioinform ; 2(4): lqaa090, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-33575634

RESUMEN

RNA function crucially depends on its structure. Thermodynamic models currently used for secondary structure prediction rely on computing the partition function of folding ensembles, and can thus estimate minimum free-energy structures and ensemble populations. These models sometimes fail in identifying native structures unless complemented by auxiliary experimental data. Here, we build a set of models that combine thermodynamic parameters, chemical probing data (DMS and SHAPE) and co-evolutionary data (direct coupling analysis) through a network that outputs perturbations to the ensemble free energy. Perturbations are trained to increase the ensemble populations of a representative set of known native RNA structures. In the chemical probing nodes of the network, a convolutional window combines neighboring reactivities, enlightening their structural information content and the contribution of local conformational ensembles. Regularization is used to limit overfitting and improve transferability. The most transferable model is selected through a cross-validation strategy that estimates the performance of models on systems on which they are not trained. With the selected model we obtain increased ensemble populations for native structures and more accurate predictions in an independent validation set. The flexibility of the approach allows the model to be easily retrained and adapted to incorporate arbitrary experimental information.

17.
J Mol Cell Biol ; 11(10): 845-859, 2019 10 25.
Artículo en Inglés | MEDLINE | ID: mdl-31336384

RESUMEN

Following the discovery of numerous long non-coding RNA (lncRNA) transcripts in the human genome, their important roles in biology and human disease are emerging. Recent progress in experimental methods has enabled the identification of structural features of lncRNAs. However, determining high-resolution structures is challenging as lncRNAs are expected to be dynamic and adopt multiple conformations, which may be modulated by interaction with protein binding partners. The X-inactive specific transcript (Xist) is necessary for X inactivation during dosage compensation in female placental mammals and one of the best-studied lncRNAs. Recent progress has provided new insights into the domain organization, molecular features, and RNA binding proteins that interact with distinct regions of Xist. The A-repeats located at the 5' end of the transcript are of particular interest as they are essential for mediating silencing of the inactive X chromosome. Here, we discuss recent progress with elucidating structural features of the Xist lncRNA, focusing on the A-repeats. We discuss the experimental and computational approaches employed that have led to distinct structural models, likely reflecting the intrinsic dynamics of this RNA. The presence of multiple dynamic conformations may also play an important role in the formation of the associated RNPs, thus influencing the molecular mechanism underlying the biological function of the Xist A-repeats. We propose that integrative approaches that combine biochemical experiments and high-resolution structural biology in vitro with chemical probing and functional studies in vivo are required to unravel the molecular mechanisms of lncRNAs.


Asunto(s)
ARN Largo no Codificante/genética , Cromosomas Humanos X/genética , Cromosomas Humanos X/metabolismo , Humanos , ARN Largo no Codificante/química , Proteínas de Unión al ARN/genética , Proteínas de Unión al ARN/metabolismo
18.
J Exp Med ; 216(7): 1700-1723, 2019 07 01.
Artículo en Inglés | MEDLINE | ID: mdl-31126966

RESUMEN

The RNase Regnase-1 is a master RNA regulator in macrophages and T cells that degrades cellular and viral RNA upon NF-κB signaling. The roles of its family members, however, remain largely unknown. Here, we analyzed Regnase-3-deficient mice, which develop hypertrophic lymph nodes. We used various mice with immune cell-specific deletions of Regnase-3 to demonstrate that Regnase-3 acts specifically within myeloid cells. Regnase-3 deficiency systemically increased IFN signaling, which increased the proportion of immature B and innate immune cells, and suppressed follicle and germinal center formation. Expression analysis revealed that Regnase-3 and Regnase-1 share protein degradation pathways. Unlike Regnase-1, Regnase-3 expression is high specifically in macrophages and is transcriptionally controlled by IFN signaling. Although direct targets in macrophages remain unknown, Regnase-3 can bind, degrade, and regulate mRNAs, such as Zc3h12a (Regnase-1), in vitro. These data indicate that Regnase-3, like Regnase-1, is an RNase essential for immune homeostasis but has diverged as key regulator in the IFN pathway in macrophages.


Asunto(s)
Homeostasis/inmunología , Inmunidad Innata , Interferones/metabolismo , Células Mieloides/metabolismo , Ribonucleasas/metabolismo , Regiones no Traducidas 3' , Animales , Autoinmunidad , Linfocitos B/metabolismo , Citometría de Flujo , Regulación de la Expresión Génica , Macrófagos/metabolismo , Ratones , Ratones Endogámicos C57BL , Ratones Noqueados , Células Mieloides/enzimología , Reacción en Cadena en Tiempo Real de la Polimerasa , Ribonucleasas/genética , Transducción de Señal , Linfocitos T/metabolismo
19.
Nucleic Acids Res ; 47(3): 1523-1531, 2019 02 20.
Artículo en Inglés | MEDLINE | ID: mdl-30481318

RESUMEN

The HIV-1 trans-activator protein Tat binds the trans-activation response element (TAR) to facilitate recruitment of the super elongation complex (SEC) to enhance transcription of the integrated pro-viral genome. The Tat-TAR interaction is critical for viral replication and the emergence of the virus from the latent state, therefore, inhibiting this interaction has long been pursued to discover new anti-viral or latency reversal agents. However, discovering active compounds that directly target RNA with high affinity and selectivity remains a significant challenge; limiting pre-clinical development. Here, we report the rational design of a macrocyclic peptide mimic of the arginine rich motif of Tat, which binds to TAR with low pM affinity and 100-fold selectivity against closely homologous RNAs. Despite these unprecedented binding properties, the new ligand (JB181) only moderately inhibits Tat-dependent reactivation in cells and recruitment of positive transcription elongation factor (P-TEFb) to TAR. The NMR structure of the JB181-TAR complex revealed that the ligand induces a structure in the TAR loop that closely mimics the P-TEFb/Tat1:57/AFF4/TAR complex. These results strongly suggest that high-affinity ligands which bind the UCU bulge are not likely to inhibit recruitment of the SEC and suggest that targeting of the TAR loop will be an essential feature of effective Tat inhibitors.


Asunto(s)
Infecciones por VIH/genética , Duplicado del Terminal Largo de VIH/genética , VIH-1/genética , Productos del Gen tat del Virus de la Inmunodeficiencia Humana/genética , Antivirales/química , Antivirales/farmacología , Infecciones por VIH/tratamiento farmacológico , Infecciones por VIH/virología , Duplicado del Terminal Largo de VIH/efectos de los fármacos , VIH-1/efectos de los fármacos , VIH-1/patogenicidad , Humanos , Ligandos , Complejos Multiproteicos/efectos de los fármacos , Complejos Multiproteicos/genética , Factor B de Elongación Transcripcional Positiva/química , Factor B de Elongación Transcripcional Positiva/genética , Unión Proteica , ARN Viral/genética , Transcripción Genética/efectos de los fármacos , Productos del Gen tat del Virus de la Inmunodeficiencia Humana/química
20.
Nurse Educ Pract ; 32: 72-77, 2018 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-30053702

RESUMEN

The purpose of the study was to obtain information concerning the effectiveness of a training program to equip nursing students in administering universal newborn hearing screening procedures, correctly recording results and clearly explaining outcomes to parent/guardians. First semester and third semester nursing students completed the National Center for Hearing Assessment and Management (NCHAM) Utah State University™ Universal Newborn Hearing Screening (UNHS) training as an in-class assignment. Students were surveyed and knowledge assessed prior to and post training. Overall results showed that all student benefited from the training.


Asunto(s)
Conocimientos, Actitudes y Práctica en Salud , Pruebas Auditivas , Tamizaje Neonatal/métodos , Estudiantes de Enfermería , Adulto , Humanos , Recién Nacido , Padres/educación , Padres/psicología , Encuestas y Cuestionarios , Utah
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