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1.
RNA ; 29(12): 1928-1938, 2023 12.
Artigo em Inglês | MEDLINE | ID: mdl-37783489

RESUMO

Ribosomal pauses are a critical part of cotranslational events including protein folding and localization. However, extended ribosome pauses can lead to ribosome collisions, resulting in the activation of ribosome rescue pathways and turnover of protein and mRNA. While this relationship has been known, there has been little exploration of how ribosomal stalls impact translation duration at a quantitative level. We have taken a method used to measure elongation time and adapted it for use in Saccharomyces cerevisiae to quantify the impact of elongation stalls. We find, in transcripts containing Arg CGA codon repeat-induced stalls, a Hel2-mediated dose-dependent decrease in protein expression and mRNA level and an elongation delay on the order of minutes. In transcripts that contain synonymous substitutions to nonoptimal Leu codons, there is a decrease in protein and mRNA levels, as well as similar elongation delay, but this occurs through a non-Hel2-mediated mechanism. Finally, we find that Dhh1 selectively increases protein expression, mRNA level, and elongation rate. This indicates that distinct poorly translated mRNAs will activate different rescue pathways despite similar elongation stall durations. Taken together, these results provide new quantitative mechanistic insight into the surveillance of translation and the roles of Hel2 and Dhh1 in mediating ribosome pausing events.


Assuntos
Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Biossíntese de Proteínas , Ribossomos/genética , Ribossomos/metabolismo , Códon/genética , Códon/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Elongação Traducional da Cadeia Peptídica , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Ubiquitina-Proteína Ligases/genética
2.
Cochrane Database Syst Rev ; 7: CD013610, 2023 07 18.
Artigo em Inglês | MEDLINE | ID: mdl-37462324

RESUMO

BACKGROUND: Cystic fibrosis (CF) is a life-limiting genetic disorder predominantly affecting the lungs and pancreas. Airway clearance techniques (ACTs) and exercise therapy are key components of physiotherapy, which is considered integral in managing CF; however, low adherence is well-documented. Poor physiotherapy adherence may lead to repeated respiratory infections, reduced exercise tolerance, breathlessness, reduced quality of life, malaise and reduced life expectancy, as well as increased use of pharmacology, healthcare access and hospital admission. Therefore, evidence-based strategies to inform clinical practice and improve adherence to physiotherapy may improve quality of life and reduce treatment burden. OBJECTIVES: To assess the effects of interventions to enhance adherence to airway clearance treatment and exercise therapy in people with CF and their effects on health outcomes, such as pulmonary exacerbations, exercise capacity and health-related quality of life. SEARCH METHODS: We searched the Cochrane Cystic Fibrosis Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. Date of last search: 1 March 2023. We also searched online trials registries and the reference lists of relevant articles and reviews. Date of last search: 28 March 2023. SELECTION CRITERIA: We included randomised controlled trials (RCTs) and quasi-RCTs of parallel design assessing any intervention aimed at enhancing adherence to physiotherapy in people with CF versus no intervention, another intervention or usual care. DATA COLLECTION AND ANALYSIS: Two review authors independently checked search results for eligible studies and independently extracted data. We used standard procedures recommended by Cochrane and assessed the certainty of evidence using the GRADE system. MAIN RESULTS: Two RCTs (77 participants with CF; age range 2 to 20 years; 44 (57%) males) met the inclusion criteria of this review. One study employed an intervention to improve adherence to exercise and the second an intervention to improve adherence to ACT. Both studies measured outcomes at baseline and at three months, but neither study formally assessed our primary outcome of adherence in terms of our planned outcome measures, and results were dependent on self-reported data. Adherence to ACTs One RCT (43 participants) assessed using specifically-composed music alongside ACTs compared to self-selected or no music (usual care). The ACT process consisted of nebuliser inhalation treatment, ACTs and relaxation or antibiotic nebuliser treatment. We graded all evidence as very low certainty. This study reported adherence to ACTs using the Morisky-Green questionnaire and also participants' perception of treatment time and enjoyment, which may influence adherence (outcome not reported specifically in this review). We are uncertain whether participants who received specifically-composed music may be more likely to adhere at six and 12 weeks compared to those who received usual care, risk ratio (RR) 1.75 (95% confidence interval (CI) 1.07 to 2.86) and RR 1.56 (95% CI 1.01 to 2.40) respectively. There may not be any difference in adherence when comparing specifically-composed music to self-selected music at six weeks, RR 1.21 (95% CI 0.87 to 1.68) or 12 weeks, RR 1.52 (95% CI 0.97 to 2.38); or self-selected music to usual care at six weeks, RR 1.44 (95% CI 0.82 to 2.52) or 12 weeks, RR 1.03 (95% CI 0.57 to 1.86). The music study also reported the number of respiratory infections requiring hospitalisation at 12 weeks, with no difference seen in the risk of hospitalisation between all groups. Adherence to exercise One RCT (24 participants) compared the provision of a manual of aerobic exercises, recommended exercise prescription plus two-weekly follow-up phone calls to reinforce exercise practice over a period of three months to verbal instructions for aerobic exercise according to the CF centre's protocol. We graded all evidence as very low certainty. We are uncertain whether an educational intervention leads to more participants in the intervention group undertaking increased regular physical activity at three months (self-report), RR 3.67 (95% CI 1.24 to 10.85), and there was no reported difference between groups in the number undertaking physical activity three times per week or undertaking at least 40 minutes of physical activity. No effect was seen on secondary outcome measures of spirometry, exercise capacity or any CF quality of life domains. This study did not report on the frequency of respiratory infections (hospitalised or not) or adverse events. AUTHORS' CONCLUSIONS: We are uncertain whether a music-based motivational intervention may increase adherence to ACTs or affect the risk of hospitalisation for a respiratory infection. We are also uncertain whether an educational intervention increases adherence to exercise or reduces the frequency of respiratory infection-related hospital admission. However, these results are largely based on self-reported data and the impact of strategies to improve adherence to ACT and exercise in children and adolescents with stable CF remains inconclusive. Given that adherence to ACT and exercise therapy are fundamental to the clinical management of people with CF, there is an urgent need for well-designed, large-scale clinical trials in this area, which should conform to the CONSORT statement for standards of reporting and use appropriate, validated outcome measures. Studies should also ensure full disclosure of data for all important clinical outcomes.


Assuntos
Fibrose Cística , Masculino , Adolescente , Criança , Humanos , Pré-Escolar , Adulto Jovem , Adulto , Feminino , Fibrose Cística/complicações , Exercício Físico , Terapia Respiratória , Qualidade de Vida , Modalidades de Fisioterapia
3.
RNA Biol ; 19(1): 636-649, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35491906

RESUMO

Protein synthesis is energetically expensive and its rate is influenced by factors such as cell type and environment. Suppression of translation is a canonical response to stressful changes in the cellular environment. In particular, inhibition of the initiation step of translation has been highlighted as the key control step in stress-induced translational suppression as mechanisms that quickly suppress initiation are well-conserved. However, cells have evolved complex regulatory means to control translation apart from initiation. Here, we examine the role of the elongation step of translation in yeast subjected to acute glucose deprivation. The use of ribosome profiling and in vivo reporter assays demonstrated elongation rates slow progressively following glucose removal. We observed that ribosome distribution broadly shifts towards the downstream ends of transcripts after both acute and gradual glucose deprivation but not in response to other stressors. Additionally, on assessed mRNAs, a correlation existed between ribosome occupancy and protein production pre-stress but was lost after stress. These results indicate that stress-induced elongation regulation causes ribosomes to slow down and build up on a considerable proportion of the transcriptome in response to glucose withdrawal. Finally, we report ribosomes that built up along transcripts are competent to resume elongation and complete protein synthesis after readdition of glucose to starved cells. This suggests that yeast has evolved mechanisms to slow translation elongation in response to glucose starvation which do not preclude continuation of protein production from those ribosomes, thereby averting a need for new initiation events to take place to synthesize proteins.Abbreviations: AUG: start codon, bp: base pair(s), CDS: coding sequence, CHX: cycloheximide, eEF2: eukaryotic elongation factor 2, LTM: lactimidomycin, nt: nucleotide, PGK1: 3-phosphoglycerate kinase, ribosomal biogenesis: ribi, RO: ribosome occupancy, RPF: ribosome protected fragment, TE: translational efficiency.


Assuntos
Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Glucose , Elongação Traducional da Cadeia Peptídica , Ribossomos/genética , Ribossomos/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo
4.
Phys Chem Chem Phys ; 21(19): 10038-10051, 2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-31046039

RESUMO

Time-resolving and controlling coupled electronic and nuclear dynamics at conical intersections on the sub-femtosecond to few-femtosecond time scale is among the challenging goals of attosecond physics. Here we present numerical simulations of time-resolved photoelectron spectroscopy of such dynamics in NO2, where the coupled electron-nuclear motion at the 2A1/2B2 conical intersection is steered on the sub-laser-cycle time scale by a nearly single-cycle, waveform controlled mid-infrared laser pulse. For a rigorous description of the photoionization dynamics, we employ ab initio energy- and geometry-resolved photoionization matrix elements obtained with the multichannel R-matrix method, using a multiconfigurational description of the molecule and a newly developed algorithm to generate photoionization dipoles that are phase consistent on the level of both the neutral and the ionic states. We find that for sufficient molecular alignment, the time- and energy-resolved anisotropy parameters of the photoelectron angular distributions provide a particularly clear picture of both the ultrafast natural molecular dynamics at the conical intersection and its modifications by the control pulse. In particular, changes in the electronic and nuclear configurations induced by the control pulse lead to the appearance of non-vanishing odd anisotropy parameters in the photoelectron spectra. These are absent in the spectra obtained without the control pulse and therefore provide sensitive, background-free diagnostic of the control.

5.
J Chem Phys ; 149(6): 064104, 2018 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-30111137

RESUMO

The photoionization of chiral molecules prepared in a coherent superposition of excited states can give access to the underlying chiral coherent dynamics in a procedure known as photoexcitation induced photoelectron circular dichroism (PXECD). As in photoelectron circular dichroism (PECD), chirality manifests as asymmetric photoelectron emission in the forward/backward direction (relative to the laser propagation direction). However, in PXECD, the asymmetric photoemission is additionally contingent on coherence. This exclusive dependence on coherence can also be seen in a different part of the photoelectron angular distribution (PAD), where it is not contingent on the chirality of the molecule, thus allowing extension of PXECD's sensitivity to tracking coherence to non-chiral molecules. Here we present a general theory of PXECD based on angular momentum algebra and derive explicit expressions for all pertinent asymmetry parameters which arise for the arbitrary polarization of pump (which prepares the superposition of excited states) and ionizing probe pulses. The theory is developed in a way that clearly and simply separates chiral and non-chiral contributions to the PAD and also demonstrates how PXECD and PECD-type contributions, which may be distinguished by whether the pump or ionizing probe pulse enables chiral response, are mixed when arbitrary polarization is used.

6.
Phys Chem Chem Phys ; 19(30): 19673-19682, 2017 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-28513724

RESUMO

We present the first ab initio multi-channel photoionization calculations for NO2 in the vicinity of the 2A1/2B2 conical intersection, for a range of nuclear geometries, using our newly developed set of tools based on the ab initio multichannel R-matrix method. Electronic correlation is included in both the neutral and the scattering states of the molecule via configuration interaction. Configuration mixing is especially important around conical intersections and avoided crossings, both pertinent for NO2, and manifests itself via significant variations in photoelectron angular distributions. The method allows for a balanced and accurate description of the photoionization/photorecombination for a number of different ionic channels in a wide range of photoelectron energies up to 100 eV. Proper account of electron correlations is crucial for interpreting time-resolved signals in photoelectron spectroscopy and high harmonic generation (HHG) from polyatomic molecules.

7.
Electrophoresis ; 37(11): 1489-97, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-26913967

RESUMO

Glycans have numerous functions in various biological processes and participate in the progress of diseases. Reliable quantitative glycomic profiling techniques could contribute to the understanding of the biological functions of glycans, and lead to the discovery of potential glycan biomarkers for diseases. Although LC-MS is a powerful analytical tool for quantitative glycomics, the variation of ionization efficiency and MS intensity bias are influencing quantitation reliability. Internal standards can be utilized for glycomic quantitation by MS-based methods to reduce variability. In this study, we used stable isotope labeled IgG2b monoclonal antibody, iGlycoMab, as an internal standard to reduce potential for errors and to reduce variabililty due to sample digestion, derivatization, and fluctuation of nanoESI efficiency in the LC-MS analysis of permethylated N-glycans released from model glycoproteins, human blood serum, and breast cancer cell line. We observed an unanticipated degradation of isotope labeled glycans, tracked a source of such degradation, and optimized a sample preparation protocol to minimize degradation of the internal standard glycans. All results indicated the effectiveness of using iGlycoMab to minimize errors originating from sample handling and instruments.


Assuntos
Glicômica/métodos , Marcação por Isótopo , Polissacarídeos/análise , Linhagem Celular Tumoral , Cromatografia Líquida , Humanos , Espectrometria de Massas , Padrões de Referência
8.
Faraday Discuss ; 194: 349-368, 2016 12 16.
Artigo em Inglês | MEDLINE | ID: mdl-27711830

RESUMO

We theoretically study high-harmonic generation in toluene, ortho-xylene and fluorobenzene driven by a 1.8 µm ultrashort pulse. We find that the chemical substitutions have a strong influence on the amplitude and phase of the emission from the highest occupied molecular orbital, despite having a small influence on the orbital itself. We show that this influence is due to the tunnel ionization step, which depends critically on the sign and amplitude of the asymptotic part of the wave function. We discuss how these effects would manifest in phase-sensitive high-harmonic generation spectroscopy experiments.

9.
Faraday Discuss ; 194: 369-405, 2016 12 16.
Artigo em Inglês | MEDLINE | ID: mdl-27722584

RESUMO

High harmonic generation (HHG) spectroscopy has opened up a new frontier in ultrafast science, where electronic dynamics can be measured on an attosecond time scale. The strong laser field that triggers the high harmonic response also opens multiple quantum pathways for multielectron dynamics in molecules, resulting in a complex process of multielectron rearrangement during ionization. Using combined experimental and theoretical approaches, we show how multi-dimensional HHG spectroscopy can be used to detect and follow electronic dynamics of core rearrangement on sub-laser cycle time scales. We detect the signatures of laser-driven hole dynamics upon ionization and reconstruct the relative phases and amplitudes for relevant ionization channels in a CO2 molecule on a sub-cycle time scale. Reconstruction of channel-resolved complex ionization amplitudes on attosecond time scales has been a long-standing goal of high harmonic spectroscopy. Our study brings us one step closer to fulfilling this initial promise and developing robust schemes for sub-femtosecond imaging of multielectron rearrangement in complex molecular systems.

11.
Eye (Lond) ; 2024 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-38565599

RESUMO

School eye health (SEH) has been on the global agenda for many years, and there is mounting evidence available to support that school-based visual screenings are one of the most effective and cost-efficient interventions to reach children over five years old. A scoping review was conducted in MEDLINE, Web of Science, PubMed, and CINHAL between February and June 2023 to identify current priorities in recent literature on school eye health in low- and middle-income countries (LMICs). Selection of relevant publications was performed with Covidence, and the main findings were classified according to the WHO Health Promoting Schools framework (HPS). A total of 95 articles were included: cross-sectional studies (n = 55), randomised controlled trials (n = 7), qualitative research (n = 7) and others. Results demonstrate that multi-level action is required to implement sustainable and integrated school eye health programmes in low and middle-income countries. The main priorities identified in this review are: standardised and rigorous protocols; cost-effective workforce; provision of suitable spectacles; compliance to spectacle wear; efficient health promotion interventions; parents and community engagement; integration of programmes in school health; inter-sectoral, government-owned programmes with long-term financing schemes. Even though many challenges remain, the continuous production of quality data such as the ones presented in this review will help governments and other stakeholders to build evidence-based, comprehensive, integrated, and context-adapted programmes and deliver quality eye care services to children all over the world.

12.
Cochrane Database Syst Rev ; (5): CD009041, 2013 May 31.
Artigo em Inglês | MEDLINE | ID: mdl-23728685

RESUMO

BACKGROUND: Dysfunctional breathing/hyperventilation syndrome (DB/HVS) is a respiratory disorder, psychologically or physiologically based, involving breathing too deeply and/or too rapidly (hyperventilation) or erratic breathing interspersed with breath-holding or sighing (DB). DB/HVS can result in significant patient morbidity and an array of symptoms including breathlessness, chest tightness, dizziness, tremor and paraesthesia. DB/HVS has an estimated prevalence of 9.5% in the general adult population, however, there is little consensus regarding the most effective management of this patient group. OBJECTIVES: (1) To determine whether breathing exercises in patients with DB/HVS have beneficial effects as measured by quality of life indices (2) To determine whether there are any adverse effects of breathing exercises in patients with DB/HVS SEARCH METHODS: We identified trials for consideration using both electronic and manual search strategies. We searched CENTRAL, MEDLINE, EMBASE, and four other databases. The latest search was in February 2013. SELECTION CRITERIA: We planned to include randomised, quasi-randomised or cluster randomised controlled trials (RCTs) in which breathing exercises, or a combined intervention including breathing exercises as a key component, were compared with either no treatment or another therapy that did not include breathing exercises in patients with DB/HVS. Observational studies, case studies and studies utilising a cross-over design were not eligible for inclusion.We considered any type of breathing exercise for inclusion in this review, such as breathing control, diaphragmatic breathing, yoga breathing, Buteyko breathing, biofeedback-guided breathing modification, yawn/sigh suppression. Programs where exercises were either supervised or unsupervised were eligible as were relaxation techniques and acute-episode management, as long as it was clear that breathing exercises were a key component of the intervention.We excluded any intervention without breathing exercises or where breathing exercises were not key to the intervention. DATA COLLECTION AND ANALYSIS: Two review authors independently checked search results for eligible studies, assessed all studies that appeared to meet the selection criteria and extracted data. We used standard procedures recommended by The Cochrane Collaboration. MAIN RESULTS: We included a single RCT assessed at unclear risk of bias, which compared relaxation therapy (n = 15) versus relaxation therapy and breathing exercises (n = 15) and a no therapy control group (n = 15).Quality of life was not an outcome measure in this RCT, and no numerical data or statistical analysis were presented in this paper. A significant reduction in the frequency and severity of hyperventilation attacks in the breathing exercise group compared with the control group was reported. In addition, a significant difference in frequency and severity of hyperventilation attacks between the breathing and relaxation group was reported. However, no information could be extracted from the paper regarding the size of the treatment effects. AUTHORS' CONCLUSIONS: The results of this systematic review are unable to inform clinical practice, based on the inclusion of only one small, poorly reported RCT. There is no credible evidence regarding the effectiveness of breathing exercises for the clinical symptoms of DB/HVS. It is currently unknown whether these interventions offer any added value in this patient group or whether specific types of breathing exercise demonstrate superiority over others. Given that breathing exercises are frequently used to treat DB/HVS, there is an urgent need for further well designed clinical trials in this area. Future trials should conform to the CONSORT statement for standards of reporting and use appropriate, validated outcome measures. Trial reports should also ensure full disclosure of data for all important clinical outcomes.


Assuntos
Exercícios Respiratórios , Hiperventilação/terapia , Terapia de Relaxamento/métodos , Adulto , Humanos , Ensaios Clínicos Controlados Aleatórios como Assunto , Transtornos Respiratórios/terapia , Síndrome
13.
Front Neurosci ; 17: 1210175, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37588516

RESUMO

Traumatic Brain Injury (TBI) is a major cause of disability and mortality, particularly among the elderly, yet our mechanistic understanding of how age renders the post-traumatic brain vulnerable to poor clinical outcomes and susceptible to neurological disease remains poorly understood. It is well established that dysregulated and sustained immune responses contribute to negative outcomes after TBI, however our understanding of the interactions between central and peripheral immune reservoirs is still unclear. The meninges serve as the interface between the brain and the immune system, facilitating important bi-directional roles in healthy and disease settings. It has been previously shown that disruption of this system exacerbates inflammation in age related neurodegenerative disorders such as Alzheimer's disease, however we have an incomplete understanding of how the meningeal compartment influences immune responses after TBI. Here, we examine the meningeal tissue and its response to brain injury in young (3-months) and aged (18-months) mice. Utilizing a bioinformatic approach, high-throughput RNA sequencing demonstrates alterations in the meningeal transcriptome at sub-acute (7-days) and chronic (1 month) timepoints after injury. We find that age alone chronically exacerbates immunoglobulin production and B cell responses. After TBI, adaptive immune response genes are up-regulated in a temporal manner, with genes involved in T cell responses elevated sub-acutely, followed by increases in B cell related genes at chronic time points after injury. Pro-inflammatory cytokines are also implicated as contributing to the immune response in the meninges, with ingenuity pathway analysis identifying interferons as master regulators in aged mice compared to young mice following TBI. Collectively these data demonstrate the temporal series of meningeal specific signatures, providing insights into how age leads to worse neuroinflammatory outcomes in TBI.

14.
PLoS One ; 18(7): e0288363, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37440485

RESUMO

The pathophysiological changes that occur after traumatic brain injury (TBI) can lead to the development of post-traumatic epilepsy, a life-long complication of brain trauma. The etiology of post-traumatic epilepsy remains unknown, but TBI brains exhibit an abnormal excitatory / inhibitory balance. In this study, we examine how brain injury alters susceptibility to chemically-induced seizures in C57Bl/6J mice, and if pharmacological enhancement of glutamate transporters can reduce chronic post-traumatic seizures. We found that controlled cortical impact (CCI) mice display delayed susceptibility to pentylenetetrazol (PTZ)-induced seizures. While CCI mice have no change in seizure susceptibility at 7d post-injury (dpi), at 70dpi they have reduced latency to PTZ-induced seizure onset, higher seizure frequency and longer seizure duration. Quantification of glutamate transporter mRNA showed that levels of Scl1a2 and Scl1a3 mRNA were increased at 7dpi, but significantly decreased at 70dpi. To test if increased levels of glutamate transporters can ameliorate delayed-onset seizure susceptibility in TBI mice, we exposed a new cohort of mice to CCI and administered ceftriaxone (200mg/kg/day) for 14d from 55-70dpi. We found that ceftriaxone significantly increased Scl1a2 and Scl1a3 in CCI mouse brain at 70dpi, and prevented the susceptibility of CCI mice to PTZ-induced seizures. This study demonstrates cortical impact can induce a delayed-onset seizure phenotype in mice. Delayed (55dpi) ceftriaxone treatment enhances glutamate transporter mRNA in the CCI brain, and reduces PTZ-induced seizures in CCI mice.


Assuntos
Lesões Encefálicas Traumáticas , Epilepsia Pós-Traumática , Humanos , Camundongos , Animais , Ceftriaxona/farmacologia , Ceftriaxona/uso terapêutico , Tempo para o Tratamento , Lesões Encefálicas Traumáticas/complicações , Lesões Encefálicas Traumáticas/tratamento farmacológico , Convulsões/induzido quimicamente , Convulsões/tratamento farmacológico , Convulsões/complicações , Pentilenotetrazol/toxicidade , Camundongos Endogâmicos C57BL , Glutamatos , Modelos Animais de Doenças
15.
bioRxiv ; 2023 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-36993688

RESUMO

Ribosomal pauses are a critical part of co-translational events including protein folding and localization. However, extended ribosome pauses can lead to ribosome collisions, resulting in the activation of ribosome rescue pathways and turnover of protein and mRNA. While this relationship has been known, the specific threshold between permissible pausing versus activation of rescue pathways has not been quantified. We have taken a method used to measure elongation time and adapted it for use in S. cerevisiae to quantify the impact of elongation stalls. We find, in transcripts containing Arg CGA codon repeat-induced stalls, a Hel2-mediated dose-dependent decrease in protein expression and mRNA level and an elongation delay on the order of minutes. In transcripts that contain synonymous substitutions to non-optimal Leu codons, there is a decrease in protein and mRNA levels, as well as similar elongation delay, but this occurs through a non-Hel2-mediated mechanism. Finally, we find that Dhh1 selectively increases protein expression, mRNA level, and elongation rate. This indicates that distinct poorly translated codons in an mRNA will activate different rescue pathways despite similar elongation stall durations. Taken together, these results provide new quantitative mechanistic insight into the surveillance of translation and the roles of Hel2 and Dhh1 in mediating ribosome pausing events.

16.
J Biomol Tech ; 33(2)2022 07 15.
Artigo em Inglês | MEDLINE | ID: mdl-36756538

RESUMO

A current method to locate sites of N-linked glycosylation on a protein involves the identification of deamidated sites after releasing the glycans with peptide-N-glycosidase F (PNGase F). PNGase F deglycosylation converts glycosylated Asn residues into Asp. The 1-Da mass tag created by this process is observable by liquid chromatography-tandem mass spectrometry analysis. A potential interference to this method of N-glycosylation site mapping is the chemical deamidation of Asn residues, which occurs spontaneously and can result in false positives. Deamidation is a pH-dependent process that results in the formation of iso-Asp (i-Asp) and native Asp (n-Asp) by a succinimide intermediate, whereas PNGase F deglycosylation results in the conversion of the glycosylation Asn residue into n-Asp. N-linked glycosylation sites can thus be identified by the presence of a single chromatographic peak corresponding to an n-Asp residue within the consensus sequence Asn-X-Ser/Thr, whereas sites of deamidation led to 2 chromatographic peaks resulting from the presence of n-Asp and i-Asp. The intent of this study is to alert investigators in the field to the potential and unexpected errors resulting from this phenomenon and to suggest a strategy to overcome this pitfall and limit the number of false-positive identifications.


Assuntos
Asparagina , Glicosilação , Peptídeo-N4-(N-acetil-beta-glucosaminil) Asparagina Amidase/química , Asparagina/química , Asparagina/metabolismo , Espectrometria de Massas , Cromatografia Líquida
17.
Methods Protoc ; 5(5)2022 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-36287049

RESUMO

In aging, the brain is more vulnerable to injury and neurodegenerative disease, but the mechanisms responsible are largely unknown. Evidence now suggests that neuroinflammation, mediated by resident brain astrocyte and microglia populations, are key players in the generation of inflammatory responses and may influence both age related processes and the initiation/progression of neurodegeneration. Consequently, targeting these cell types individually and collectively may aid in the development of novel disease-modifying therapies. We have optimized and characterized a protocol for the effective sequential isolation of both microglia and astrocytes from the adult mouse brain in young and aged mice. We demonstrate a technique for the sequential isolation of these immune cells by using magnetic beads technology, optimized to increase yield and limit potential artifacts in downstream transcriptomic applications, including RNA-sequencing pipelines. This technique is versatile, cost-effective, and reliable for the study of responses within the same biological context, simultaneously being advantageous in reducing mice numbers required to assess cellular responses in normal and age-related pathological conditions.

18.
Elife ; 112022 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-36107469

RESUMO

During times of unpredictable stress, organisms must adapt their gene expression to maximize survival. Along with changes in transcription, one conserved means of gene regulation during conditions that quickly repress translation is the formation of cytoplasmic phase-separated mRNP granules such as P-bodies and stress granules. Previously, we identified that distinct steps in gene expression can be coupled during glucose starvation as promoter sequences in the nucleus are able to direct the subcellular localization and translatability of mRNAs in the cytosol. Here, we report that Rvb1 and Rvb2, conserved ATPase proteins implicated as protein assembly chaperones and chromatin remodelers, were enriched at the promoters and mRNAs of genes involved in alternative glucose metabolism pathways that we previously found to be transcriptionally upregulated but translationally downregulated during glucose starvation in yeast. Engineered Rvb1/Rvb2-binding on mRNAs was sufficient to sequester mRNAs into mRNP granules and repress their translation. Additionally, this Rvb tethering to the mRNA drove further transcriptional upregulation of the target genes. Further, we found that depletion of Rvb2 caused decreased alternative glucose metabolism gene mRNA induction, but upregulation of protein synthesis during glucose starvation. Overall, our results point to Rvb1/Rvb2 coupling transcription, mRNA granular localization, and translatability of mRNAs during glucose starvation. This Rvb-mediated rapid gene regulation could potentially serve as an efficient recovery plan for cells after stress removal.


Assuntos
Adenosina Trifosfatases/metabolismo , Glucose , Proteínas de Saccharomyces cerevisiae/metabolismo , Fatores de Transcrição/metabolismo , Cromatina/metabolismo , DNA Helicases/metabolismo , Glucose/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética
19.
Biology (Basel) ; 11(7)2022 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-36101412

RESUMO

Traumatic brain injury (TBI) is a significant risk factor for the development of sleep and circadian rhythm impairments. In this study we compare the circadian rhythms and sleep patterns in the high-frequency head impact (HFHI) and controlled cortical impact (CCI) mouse models of TBI. These mouse models have different injury mechanisms key differences of pathology in brain regions controlling circadian rhythms and EEG wave generation. We found that both HFHI and CCI caused dysregulation in the diurnal expression of core circadian genes (Bmal1, Clock, Per1,2, Cry1,2) at 24 h post-TBI. CCI mice had reduced locomotor activity on running wheels in the first 7 d post-TBI; however, both CCI and HFHI mice were able to maintain circadian behavior cycles even in the absence of light cues. We used implantable EEG to measure sleep cycles and brain activity and found that there were no differences in the time spent awake, in NREM or REM sleep in either TBI model. However, in the sleep states, CCI mice have reduced delta power in NREM sleep and reduced theta power in REM sleep at 7 d post-TBI. Our data reveal that different types of brain trauma can result in distinct patterns of circadian and sleep disruptions and can be used to better understand the etiology of sleep disorders after TBI.

20.
J Intensive Care Soc ; 23(2): 183-190, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35615241

RESUMO

Background: The unprecedented increase in critically ill patients due to the COVID-19 pandemic mandated rapid training in critical care for redeployed staff to work safely in intensive care units (ICU). Methods: The COVID-19 ICU Remote-Learning Course (CIRLC) is a remote delivery course developed in response to the pandemic. This was a one-day course focused on the fundamentals of Intensive Care. The course used blended learning with recorded lectures and interactive tutorials delivered by shielding and frontline ICU trained professionals. The course was developed within one week and piloted at three NHS Trusts. It was then made publicly available free of charge to redeployed healthcare professionals across the UK and Ireland. An iterative cycle of improvement was used to update the course content weekly. A course confidence questionnaire with quantitative and qualitative questions was used to evaluate effectiveness. Data is reported as n (%), means (SD) and thematic analysis was used for the open questions. Results: 1,269 candidates from 171 organisations completed the course, with 99 volunteer trainers. 96% of respondents rated the course as very or extremely useful. 86% rated the online platform as excellent. Overall confidence improved from 2.7/5 to 3.9/5. Qualitative data showed that the course was pitched at the appropriate level, accessible and built clinicians confidence to work in intensive care. Conclusion: This model of educational delivery with a rapid iteration cycle was a pragmatic, effective solution to knowledge-based training under social distancing measures. Whilst full course evaluation was not possible, we believe that this work demonstrates practical guidance on educational response in a pandemic as well as highlighting the altruistic nature of the critical care community.

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