RESUMEN
Posttraumatic stress disorder (PTSD) is a debilitating psychosomatic condition characterized by impairment of brain fear circuits and persistence of exceptionally strong associative memories resistant to extinction. In this study, we investigated the neural and behavioral consequences of inhibiting protein synthesis, a process known to suppress the formation of conventional aversive memories, in an established PTSD animal model based on contextual fear conditioning in mice. Control animals were subjected to the conventional fear conditioning task. Utilizing c-Fos neural activity mapping, we found that the retrieval of PTSD and normal aversive memories produced activation of an overlapping set of brain structures. However, several specific areas, such as the infralimbic cortex and the paraventricular thalamic nucleus, showed an increase in the PTSD group compared to the normal aversive memory group. Administration of protein synthesis inhibitor before PTSD induction disrupted the formation of traumatic memories, resulting in behavior that matched the behavior of mice with usual aversive memory. Concomitant with this behavioral shift was a normalization of brain c-Fos activation pattern matching the one observed in usual fear memory. Our findings demonstrate that inhibiting protein synthesis during traumatic experiences significantly impairs the development of PTSD in a mouse model. These data provide insights into the neural underpinnings of protein synthesis-dependent traumatic memory formation and open prospects for the development of new therapeutic strategies for PTSD prevention.
Asunto(s)
Miedo , Memoria , Proteínas Proto-Oncogénicas c-fos , Trastornos por Estrés Postraumático , Animales , Masculino , Ratones , Encéfalo/metabolismo , Modelos Animales de Enfermedad , Ratones Endogámicos C57BL , Biosíntesis de Proteínas , Inhibidores de la Síntesis de la Proteína/farmacología , Proteínas Proto-Oncogénicas c-fos/metabolismo , Trastornos por Estrés Postraumático/metabolismoRESUMEN
Prolyl-tRNA synthetase (ProRS), belonging to the family of aminoacyl-tRNA synthetases responsible for pairing specific amino acids with their respective tRNAs, is categorized into two distinct types: the eukaryote/archaeon-like type (E-type) and the prokaryote-like type (P-type). Notably, these types are specific to their corresponding cognate tRNAs. In an intriguing paradox, Thermus thermophilus ProRS (TtProRS) aligns with the E-type ProRS but selectively charges the P-type tRNAPro, featuring the bacterium-specific acceptor-stem elements G72 and A73. This investigation reveals TtProRS's notable resilience to the inhibitor halofuginone, a synthetic derivative of febrifugine emulating Pro-A76, resembling the characteristics of the P-type ProRS. Furthermore, akin to the P-type ProRS, TtProRS identifies its cognate tRNA through recognition of the acceptor-stem elements G72/A73, along with the anticodon elements G35/G36. However, in contrast to the P-type ProRS, which relies on a strictly conserved R residue within the bacterium-like motif 2 loop for recognizing G72/A73, TtProRS achieves this through a non-conserved sequence, RTR, within the otherwise non-interacting eukaryote-like motif 2 loop. This investigation sheds light on the adaptive capacity of a typically conserved housekeeping enzyme to accommodate a novel substrate.
Asunto(s)
Aminoacil-ARNt Sintetasas , ARN de Transferencia de Prolina , Thermus thermophilus , Thermus thermophilus/química , Thermus thermophilus/enzimología , Thermus thermophilus/genética , Aminoacil-ARNt Sintetasas/química , Aminoacil-ARNt Sintetasas/genética , Aminoacil-ARNt Sintetasas/metabolismo , ARN de Transferencia de Prolina/química , ARN de Transferencia de Prolina/genética , ARN de Transferencia de Prolina/metabolismo , Secuencias de Aminoácidos , Secuencia de Aminoácidos , Secuencias Invertidas Repetidas , Evolución Molecular , Levaduras/enzimología , Inhibidores de la Síntesis de la Proteína/farmacología , Proteínas Bacterianas/química , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Piperidinas/farmacología , Quinazolinonas/farmacologíaRESUMEN
The eukaryotic translation initiation factor eIF5B is a bacterial IF2 ortholog that plays an important role in ribosome joining and stabilization of the initiator tRNA on the AUG start codon during the initiation of translation. We identified the fluorophenyl oxazole derivative 2,2-dibromo-1-(2-(4-fluorophenyl)benzo[d]oxazol-5-yl)ethanone quinolinol as an inhibitor of fungal protein synthesis using an in vitro translation assay in a fungal system. Mutants resistant to this compound were isolated in Saccharomyces cerevisiae and were demonstrated to contain amino acid substitutions in eIF5B that conferred the resistance. These results suggest that eIF5B is a target of potential antifungal compound and that mutation of eIF5B can confer resistance. Subsequent identification of 16 other mutants revealed that primary mutations clustered mainly on domain 2 of eIF5B and secondarily mainly on domain 4. Domain 2 has been implicated in the interaction with the small ribosomal subunit during initiation of translation. The tested translation inhibitor could act by weakening the functional contact between eIF5B and the ribosome complex. This data provides the basis for the development of a new family of antifungals.
Asunto(s)
Antifúngicos , Factores Eucarióticos de Iniciación , Saccharomyces cerevisiae , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/efectos de los fármacos , Factores Eucarióticos de Iniciación/metabolismo , Factores Eucarióticos de Iniciación/genética , Antifúngicos/farmacología , Mutación , Biosíntesis de Proteínas/efectos de los fármacos , Farmacorresistencia Fúngica/genética , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/antagonistas & inhibidores , Inhibidores de la Síntesis de la Proteína/farmacología , Sustitución de AminoácidosRESUMEN
The consolidation of memory is thought to ultimately depend on the synthesis of new proteins, since translational inhibitors such as anisomycin and cycloheximide adversely affect the permanence of long-term memory. However, when applied directly in brain, these agents also profoundly suppress neural activity to an extent that is directly correlated to the degree of protein synthesis inhibition caused. Given that neural activity itself is likely to help mediate consolidation, this finding is a serious criticism of the strict de novo protein hypothesis of memory. Here, we test the neurophysiological effects of another translational inhibitor, emetine. Unilateral intra-hippocampal infusion of emetine suppressed ongoing local field and multiunit activity at ipsilateral sites as compared to the contralateral hippocampus in a fashion that was positively correlated to the degree of protein synthesis inhibition as confirmed by autoradiography. This suppression of activity was also specific to the circumscribed brain region in which protein synthesis inhibition took place. These experiments provide further evidence that ongoing protein synthesis is necessary and fundamental for neural function and suggest that the disruption of memory observed in behavioral experiments using translational inhibitors may be due, in large part, to neural suppression.
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Emetina , Hipocampo , Inhibidores de la Síntesis de la Proteína , Emetina/farmacología , Animales , Inhibidores de la Síntesis de la Proteína/farmacología , Hipocampo/efectos de los fármacos , Hipocampo/metabolismo , Hipocampo/fisiología , Masculino , Biosíntesis de Proteínas/efectos de los fármacos , Biosíntesis de Proteínas/fisiología , Ratas , Neuronas/efectos de los fármacos , Potenciales de Acción/efectos de los fármacos , Potenciales de Acción/fisiología , Ratas Sprague-DawleyRESUMEN
The transmembrane protein Agp2, initially shown as a transporter of L-carnitine, mediates the high-affinity transport of polyamines and the anticancer drug bleomycin-A5. Cells lacking Agp2 are hyper-resistant to polyamine and bleomycin-A5. In these earlier studies, we showed that the protein synthesis inhibitor cycloheximide blocked the uptake of bleomycin-A5 into the cells suggesting that the drug uptake system may require de novo synthesis. However, our recent findings demonstrated that cycloheximide, instead, induced rapid degradation of Agp2, and in the absence of Agp2 cells are resistant to cycloheximide. These observations raised the possibility that the degradation of Agp2 may allow the cell to alter its drug resistance network to combat the toxic effects of cycloheximide. In this study, we show that membrane extracts from agp2Δ mutants accentuated several proteins that were differentially expressed in comparison to the parent. Mass spectrometry analysis of the membrane extracts uncovered the pleiotropic drug efflux pump, Pdr5, involved in the efflux of cycloheximide, as a key protein upregulated in the agp2Δ mutant. Moreover, a global gene expression analysis revealed that 322 genes were differentially affected in the agp2Δ mutant versus the parent, including the prominent PDR5 gene and genes required for mitochondrial function. We further show that Agp2 is associated with the upstream region of the PDR5 gene, leading to the hypothesis that cycloheximide resistance displayed by the agp2Δ mutant is due to the derepression of the PDR5 gene.
Asunto(s)
Transportadoras de Casetes de Unión a ATP , Cicloheximida , Inhibidores de la Síntesis de la Proteína , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Cicloheximida/farmacología , Inhibidores de la Síntesis de la Proteína/farmacología , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Transportadoras de Casetes de Unión a ATP/metabolismo , Transportadoras de Casetes de Unión a ATP/genética , Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/efectos de los fármacos , Saccharomyces cerevisiae/genética , Regulación hacia Arriba/efectos de los fármacos , Farmacorresistencia Fúngica/genética , Farmacorresistencia Fúngica/efectos de los fármacos , Regulación Fúngica de la Expresión Génica/efectos de los fármacosRESUMEN
The benefits of physical exercise (PE) on memory consolidation have been well-documented in both healthy and memory-impaired animals. However, the underlying mechanisms through which PE exerts these effects are still unclear. In this study, we aimed to investigate the role of hippocampal protein synthesis in memory modulation by acute PE in rats. After novel object recognition (NOR) training, rats were subjected to a 30-min moderate-intensity acute PE on the treadmill, while control animals did not undergo any procedures. Using anisomycin (ANI) and rapamycin (RAPA), compounds that inhibit protein synthesis through different mechanisms, we manipulated protein synthesis in the CA1 region of the hippocampus to examine its contribution to memory consolidation. Memory was assessed on days 1, 7, and 14 post-training. Our results showed that inhibiting protein synthesis by ANI or RAPA impaired NOR memory consolidation in control animals. However, acute PE prevented this impairment without affecting memory persistence. We also evaluated brain-derived neurotrophic factor (BDNF) levels after acute PE at 0.5h, 2h, and 12h afterward and found no differences in levels compared to animals that did not engage in acute PE or were only habituated to the treadmill. Therefore, our findings suggest that acute PE could serve as a non-pharmacological intervention to enhance memory consolidation and prevent memory loss in conditions associated with hippocampal protein synthesis inhibition. This mechanism appears not to depend on BDNF synthesis in the early hours after exercise.
Asunto(s)
Amnesia , Anisomicina , Factor Neurotrófico Derivado del Encéfalo , Hipocampo , Condicionamiento Físico Animal , Ratas Wistar , Animales , Masculino , Condicionamiento Físico Animal/fisiología , Ratas , Hipocampo/metabolismo , Hipocampo/efectos de los fármacos , Anisomicina/farmacología , Factor Neurotrófico Derivado del Encéfalo/metabolismo , Factor Neurotrófico Derivado del Encéfalo/biosíntesis , Amnesia/metabolismo , Amnesia/prevención & control , Inhibidores de la Síntesis de la Proteína/farmacología , Sirolimus/farmacología , Biosíntesis de Proteínas/efectos de los fármacos , Biosíntesis de Proteínas/fisiología , Consolidación de la Memoria/efectos de los fármacos , Consolidación de la Memoria/fisiología , Reconocimiento en Psicología/efectos de los fármacos , Reconocimiento en Psicología/fisiologíaRESUMEN
Shigellosis remains a common gastrointestinal disease mostly in children < 5 years of age in developing countries. Azithromycin (AZM), a macrolide, is currently the first-line treatment for shigellosis in Bangladesh; ciprofloxacin (CIP) and ceftriaxone (CRO) are also used frequently. We aimed to evaluate the current epidemiology of antimicrobial resistance (AMR) and mechanism(s) of increasing macrolide resistance in Shigella in Bangladesh. A total of 2407 clinical isolates of Shigella from 2009 to 2016 were studied. Over the study period, Shigella sonnei was gradually increasing and become predominant (55%) over Shigella flexneri (36%) by 2016. We used CLSI-guided epidemiological cut-off value (ECV) for AZM in Shigella to set resistance breakpoints (zone-diameter ≤ 15 mm for S. flexneri and ≤ 11 mm for S. sonnei). Between 2009 and 2016, AZM resistance increased from 22% to approximately 60%, CIP resistance increased by 40%, and CRO resistance increased from zero to 15%. The mphA gene was the key macrolide resistance factor in Shigella; a 63MDa conjugative middle-range plasmid was harboring AZM and CRO resistance factors. Our findings show that, especially after 2014, there has been a rapid increase in resistance to the three most effective antibiotics. The rapid spread of macrolide (AZM) resistance genes among Shigella are driven by horizontal gene transfer rather than direct lineage.
Asunto(s)
Disentería Bacilar , Shigella , Niño , Humanos , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Disentería Bacilar/tratamiento farmacológico , Disentería Bacilar/epidemiología , Macrólidos/farmacología , Macrólidos/uso terapéutico , Farmacorresistencia Bacteriana/genética , Azitromicina/farmacología , Azitromicina/uso terapéutico , Ciprofloxacina/farmacología , Ciprofloxacina/uso terapéutico , Ceftriaxona/farmacología , Pruebas de Sensibilidad Microbiana , Inhibidores de la Síntesis de la Proteína/farmacología , Plásmidos/genéticaRESUMEN
Plasticity in gene expression allows bacteria to adapt to diverse environments. This is particularly relevant in the dynamic niche of the human intestinal tract; however, transcriptional networks remain largely unknown for gut-resident bacteria. Here we apply differential RNA sequencing (RNA-seq) and conventional RNA-seq to the model gut bacterium Bacteroides thetaiotaomicron to map transcriptional units and profile their expression levels across 15 in vivo-relevant growth conditions. We infer stress- and carbon source-specific transcriptional regulons and expand the annotation of small RNAs (sRNAs). Integrating this expression atlas with published transposon mutant fitness data, we predict conditionally important sRNAs. These include MasB, which downregulates tetracycline tolerance. Using MS2 affinity purification and RNA-seq, we identify a putative MasB target and assess its role in the context of the MasB-associated phenotype. These data-publicly available through the Theta-Base web browser ( http://micromix.helmholtz-hiri.de/bacteroides/ )-constitute a valuable resource for the microbiome community.
Asunto(s)
Bacteroides thetaiotaomicron , Humanos , Bacteroides thetaiotaomicron/genética , Transcriptoma , ARN , Inhibidores de la Síntesis de la Proteína , TetraciclinasRESUMEN
The essential yeast protein GPN-loop GTPase 1 (Npa3) plays a critical role in RNA polymerase II (RNAPII) assembly and subsequent nuclear import. We previously identified a synthetic lethal interaction between a mutant lacking the carboxy-terminal 106-amino acid tail of Npa3 (npa3ΔC) and a bud27Δ mutant. As the prefoldin-like Bud27 protein participates in ribosome biogenesis and translation, we hypothesized that Npa3 may also regulate these biological processes. We investigated this proposal by using Saccharomyces cerevisiae strains episomally expressing either wild-type Npa3 or hypomorphic mutants (Npa3ΔC, Npa3K16R, and Npa3G70A). The Npa3ΔC mutant fully supports RNAPII nuclear localization and activity. However, the Npa3K16R and Npa3G70A mutants only partially mediate RNAPII nuclear targeting and exhibit a higher reduction in Npa3 function. Cell proliferation in these strains displayed an increased sensitivity to protein synthesis inhibitors hygromycin B and geneticin/G418 (npa3G70A > npa3K16R > npa3ΔC > NPA3 cells) but not to transcriptional elongation inhibitors 6-azauracil, mycophenolic acid or 1,10-phenanthroline. In all three mutant strains, the increase in sensitivity to both aminoglycoside antibiotics was totally rescued by expressing NPA3. Protein synthesis, visualized by quantifying puromycin incorporation into nascent-polypeptide chains, was markedly more sensitive to hygromycin B inhibition in npa3ΔC, npa3K16R, and npa3G70A than NPA3 cells. Notably, high-copy expression of the TIF11 gene, that encodes the eukaryotic translation initiation factor 1A (eIF1A) protein, completely suppressed both phenotypes (of reduced basal cell growth and increased sensitivity to hygromycin B) in npa3ΔC cells but not npa3K16R or npa3G70A cells. We conclude that Npa3 plays a critical RNAPII-independent and previously unrecognized role in translation initiation.
Asunto(s)
Factor 1 Eucariótico de Iniciación , Higromicina B , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Núcleo Celular/metabolismo , Núcleo Celular/genética , GTP Fosfohidrolasas/genética , GTP Fosfohidrolasas/metabolismo , Higromicina B/farmacología , Biosíntesis de Proteínas/efectos de los fármacos , Inhibidores de la Síntesis de la Proteína/farmacología , ARN Polimerasa II/genética , ARN Polimerasa II/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/crecimiento & desarrollo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas de Unión al GTP Monoméricas/genética , Proteínas de Unión al GTP Monoméricas/metabolismoRESUMEN
It is widely accepted that fear memories are consolidated through protein synthesis-dependent changes in the basolateral amygdala complex (BLA). However, recent studies show that protein synthesis is not required to consolidate the memory of a new dangerous experience when it is similar to a prior experience. Here, we examined whether the protein synthesis requirement for consolidating the new experience varies with its spatial and temporal distance from the prior experience. Female and male rats were conditioned to fear a stimulus (S1, e.g., light) paired with shock in stage 1 and a second stimulus (S2, e.g., tone) that preceded additional S1-shock pairings (S2-S1-shock) in stage 2. The latter stage was followed by a BLA infusion of a protein synthesis inhibitor, cycloheximide, or vehicle. Subsequent testing with S2 revealed that protein synthesis in the BLA was not required to consolidate fear to S2 when the training stages occurred 48â h apart in the same context; was required when they were separated by 14â d or occurred in different contexts; but was again not required if S1 was re-presented after the delay or in the different context. Similarly, protein synthesis in the BLA was not required to reconsolidate fear to S2 when the training stages occurred 48â h apart but was required when they occurred 14â d apart. Thus, the protein synthesis requirement for consolidating/reconsolidating fear memories in the BLA is determined by similarity between present and past experiences, the time and place in which they occur, and reminders of the past experiences.
Asunto(s)
Complejo Nuclear Basolateral , Consolidación de la Memoria , Ratas , Masculino , Femenino , Animales , Complejo Nuclear Basolateral/fisiología , Consolidación de la Memoria/fisiología , Inhibidores de la Síntesis de la Proteína/farmacología , Cicloheximida/farmacología , Miedo/fisiologíaRESUMEN
Hyperactivated KRAS mutations fuel tumorigenesis and represent attractive targets for cancer treatment. While covalent inhibitors have shown clinical benefits against the KRASG12C mutant, advancements for non-G12C mutants remain limited, highlighting the urgent demand for pan-KRAS inhibitors. RNA G-quadruplexes (rG4s) in the 5'-untranslated region of KRAS mRNA can regulate KRAS translation, making them promising targets for pan-KRAS inhibitor development. Herein, we designed and synthesized 50 novel coumarin-quinolinium derivatives, leveraging our previously developed rG4-specific ligand, QUMA-1. Notably, several compounds exhibited potent antiproliferative activity against cancer cells as pan-KRAS translation inhibitors. Among them, 15a displayed exceptional capability in stabilizing KRAS rG4s, suppressing KRAS translation, and consequently modulating MAPK and PI3K-AKT pathways. 15a induced cell cycle arrest, prompted apoptosis in KRAS-driven cancer cells, and effectively inhibited tumor growth in a KRAS mutant xenograft model. These findings underscore the potential of 15a as a pan-KRAS translation inhibitor, offering a novel and promising approach to target various KRAS-driven cancers.
Asunto(s)
G-Cuádruplex , Proteínas Proto-Oncogénicas p21(ras) , Humanos , Línea Celular Tumoral , Proteínas Proto-Oncogénicas p21(ras)/genética , Proteínas Proto-Oncogénicas p21(ras)/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Inhibidores de la Síntesis de la Proteína , MutaciónRESUMEN
Circadian-paced biological processes are key to physiology and required for metabolic, immunologic, and cardiovascular homeostasis. Core circadian clock components are transcription factors whose half-life is precisely regulated, thereby controlling the intrinsic cellular circadian clock. Genetic disruption of molecular clock components generally leads to marked pathological events phenotypically affecting behavior and multiple aspects of physiology. Using a transcriptional signature similarity approach, we identified anti-cancer protein synthesis inhibitors as potent modulators of the cardiomyocyte molecular clock. Eukaryotic protein translation inhibitors, ranging from translation initiation (rocaglates, 4-EGI1, etc.) to ribosomal elongation inhibitors (homoharringtonine, puromycin, etc.), were found to potently ablate protein abundance of REV-ERBα, a repressive nuclear receptor and component of the molecular clock. These inhibitory effects were observed both in vitro and in vivo and could be extended to PER2, another component of the molecular clock. Taken together, our observations suggest that the activity spectrum of protein synthesis inhibitors, whose clinical use is contemplated not only in cancers but also in viral infections, must be extended to circadian rhythm disruption, with potential beneficial or iatrogenic effects upon acute or prolonged administration.
Asunto(s)
Relojes Circadianos , Relojes Circadianos/genética , Ritmo Circadiano/fisiología , Inhibidores de la Síntesis de la Proteína , Miembro 1 del Grupo D de la Subfamilia 1 de Receptores Nucleares/metabolismo , CorazónRESUMEN
Linezolid is the first and only oxazolidinone antibacterial drug was approved in the last 35 years. It exhibits bacteriostatic efficacy against M. tuberculosis and is a crucial constituent of the BPaL regimen (Bedaquiline, Pretomanid, and Linezolid), which was authorized by the FDA in 2019 for the treatment of XDR-TB or MDR-TB. Despite its unique mechanism of action, Linezolid carries a considerable risk of toxicity, including myelosuppression and serotonin syndrome (SS), which is caused by inhibition of mitochondrial protein synthesis (MPS) and monoamine oxidase (MAO), respectively. Based on the structure toxicity relationship (STR) of Linezolid, in this work, we used a bioisosteric replacement approach to optimize the structure of Linezolid at the C-ring and/or C-5 position for myelosuppression and serotogenic toxicity. Extensive hierarchical multistep docking, drug likeness prediction, molecular binding interactions analyses, and toxicity assessment identified three promising compounds (3071, 7549 and 9660) as less toxic potential modulators of Mtb EthR protein. Compounds 3071, 7549 and 9660 were having the significant docking score of -12.696 Kcal/mol, -12.681 Kcal/mol and -15.293 Kcal/mol towards the Mtb EthR protein with less MAO-A and B affinity [compound 3071: MAO A (-4.799 Kcal/mol) and MAO B (-6.552 Kcal/mol); compound 7549: MAO A (> -2.00 Kcal/mol) and MAO B (> -2.00 Kcal/mol) and compound 9660: MAO A (> -5.678 Kcal/mol) and MAO B (> -6.537Kcal/mol) and none of them shown the Leukopenia as a side effect due to the Myelosuppression. The MD simulation results and binding free energy estimations correspond well with docking analyses, indicating that the proposed compounds bind and inhibit the EthR protein more effectively than Linezolid. The quantum mechanical and electrical characteristics were evaluated using density functional theory (DFT), which also demonstrated that the proposed compounds are more reactive than Linezolid.Communicated by Ramaswamy H. Sarma.
Asunto(s)
Mycobacterium tuberculosis , Tuberculosis Resistente a Múltiples Medicamentos , Humanos , Linezolid/efectos adversos , Inhibidores de la Síntesis de la Proteína/farmacología , Inhibidores de la Síntesis de la Proteína/uso terapéutico , Tuberculosis Resistente a Múltiples Medicamentos/tratamiento farmacológico , Tuberculosis Resistente a Múltiples Medicamentos/microbiología , Monoaminooxidasa , Resistencia a Múltiples Medicamentos , Simulación del Acoplamiento MolecularRESUMEN
BACKGROUND: The widespread use of aminoglycosides is a prevalent cause of sensorineural hearing loss. Patients receiving aminoglycosides usually have elevated levels of circulating stress hormones due to disease or physiological stress; however, whether the stress hormone cortisol impacts aminoglycoside-mediated injury of cochlear hair cells has not been fully investigated. METHODS: House Ear Institute-Organ of Corti 1 (HEI-OC1) cells with or without cortisol pretreatment were exposed to gentamicin, we investigated the effect of cortisol pretreatment on gentamicin ototoxicity by assessing cell viability. Molecular pathogenesis was explored by detecting apoptosis and oxidative stress. Meanwhile, by inhibiting glucocorticoid receptors (GR) and mineralocorticoid receptors (MR), the potential roles of receptor types in cortisol-mediated sensitization were evaluated. RESULTS: Cortisol concentrations below 75 µmol/l did not affect cell viability. However, pretreatment with 50 µmol/l cortisol for 24 hours sensitized hair cells to gentamicin-induced apoptosis. Further mechanistic studies revealed that cortisol significantly increased hair cell apoptosis and oxidative stress, and altered apoptosis-related protein expressions induced by gentamicin. In addition, blockade of either GR or MR attenuated cortisol-induced hair cell sensitization to gentamicin toxicity. CONCLUSION: Cortisol pretreatment increased mammalian hair cell susceptibility to gentamicin toxicity. Sensitization was related to the activation of the intrinsic apoptotic pathway and excessive generation of reactive oxygen species. Cortisol may exacerbate aminoglycoside ototoxicity.
Asunto(s)
Antibacterianos , Gentamicinas , Células Ciliadas Auditivas , Hidrocortisona , Ototoxicidad , Animales , Humanos , Aminoglicósidos , Antibacterianos/efectos adversos , Antibacterianos/farmacología , Apoptosis , Gentamicinas/efectos adversos , Gentamicinas/toxicidad , Células Ciliadas Auditivas/efectos de los fármacos , Hidrocortisona/farmacología , Mamíferos/metabolismo , Ototoxicidad/etiología , Ototoxicidad/metabolismo , Inhibidores de la Síntesis de la Proteína , Especies Reactivas de Oxígeno/metabolismoRESUMEN
Microplastics (MPs) and antibiotics are ubiquitous in aquatic ecosystems, and their accumulation and combined effects are considered emerging threats that may affect biodiversity and ecosystem function. The particle size of microplastics plays an important role in their combined effects with antibiotics. Submerged macrophytes are crucial in maintaining the health and stability of freshwater ecosystems. However, little is known about the combined effects of different particle size of MPs and antibiotics on freshwater plants, particularly their effects on submerged macrophyte communities. Thus, there is an urgent need to study their effects on the macrophyte communities to provide essential information for freshwater ecosystem management. In the present study, a mesocosm experiment was conducted to explore the effects of three particle sizes (5 µm, 50 µm, and 500 µm) of polystyrene-microplastics (PSMPs) (75 mg/L), tetracycline (TC) (50 mg/L), and their co-pollutants on interactions between Hydrilla verticillata and Elodea nuttallii. Our results showed that the effects of MPs are size-dependent on macrophytes at the community level rather than at the population level, and that small and medium sized MPs can promote the growth of the two test macrophytes at the community level. In addition, macrophytes at the community level have a stronger resistance to pollutant stress than those at the population level. Combined exposure to MPs and TC co-pollutants induces species-specific responses and antagonistic toxic effects on the physio-biochemical traits of submerged macrophytes. Our study provides evidence that MPs and co-pollutants not only affect the morphology and physiology at the population level but also the interactions between macrophytes. Thus, there are promising indications on the potential consequences of MPs and co-pollutants on macrophyte community structure, which suggests that future studies should focus on the effects of microplastics and their co-pollutants on aquatic macrophytes at the community level rather than only at the population level. This will improve our understanding of the profound effects of co-pollutants in aquatic environments on the structure and behavior of aquatic communities and ecosystems.
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Ecosistema , Contaminantes Ambientales , Microplásticos/toxicidad , Plásticos/toxicidad , Tamaño de la Partícula , Inhibidores de la Síntesis de la Proteína , Antibacterianos , TetraciclinasRESUMEN
In response to stress stimuli, eukaryotic cells typically suppress protein synthesis. This leads to the release of mRNAs from polysomes, their condensation with RNA-binding proteins, and the formation of non-membrane-bound cytoplasmic compartments called stress granules (SGs). SGs contain 40S but generally lack 60S ribosomal subunits. It is known that cycloheximide, emetine, and anisomycin, the ribosome inhibitors that block the progression of 80S ribosomes along mRNA and stabilize polysomes, prevent SG assembly. Conversely, puromycin, which induces premature termination, releases mRNA from polysomes and stimulates the formation of SGs. The same effect is caused by some translation initiation inhibitors, which lead to polysome disassembly and the accumulation of mRNAs in the form of stalled 48S preinitiation complexes. Based on these and other data, it is believed that the trigger for SG formation is the presence of mRNA with extended ribosome-free segments, which tend to form condensates in the cell. In this study, we evaluated the ability of various small-molecule translation inhibitors to block or stimulate the assembly of SGs under conditions of severe oxidative stress induced by sodium arsenite. Contrary to expectations, we found that ribosome-targeting elongation inhibitors of a specific type, which arrest solitary 80S ribosomes at the beginning of the mRNA coding regions but do not interfere with all subsequent ribosomes in completing translation and leaving the transcripts (such as harringtonine, lactimidomycin, or T-2 toxin), completely prevent the formation of arsenite-induced SGs. These observations suggest that the presence of even a single 80S ribosome on mRNA is sufficient to prevent its recruitment into SGs, and the presence of extended ribosome-free regions of mRNA is not sufficient for SG formation. We propose that mRNA entry into SGs may be mediated by specific contacts between RNA-binding proteins and those regions on 40S subunits that remain inaccessible when ribosomes are associated.
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Biosíntesis de Proteínas , Gránulos de Estrés , ARN Mensajero/metabolismo , Gránulos Citoplasmáticos , Ribosomas/metabolismo , Inhibidores de la Síntesis de la Proteína/farmacología , Proteínas de Unión al ARN/metabolismoRESUMEN
Oxazolidinones represent a significant class of synthetic bacterial protein synthesis inhibitors that are primarily effective against Gram-positive bacteria. The commercial success of linezolid, the first FDA-approved oxazolidinone antibiotic, has motivated researchers to develop more potent oxazolidinones by employing various drug development strategies to fight against antimicrobial resistance, some of which have shown promising results. Thus, this Perspective aims to discuss the strategies employed in constructing oxazolidinone-based antibacterial agents and summarize recent advances in discovering oxazolidinone antibiotics to provide valuable insights for potentially developing next-generation oxazolidinone antibacterial agents or other pharmaceuticals.
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Oxazolidinonas , Oxazolidinonas/farmacología , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Linezolid/farmacología , Inhibidores de la Síntesis de la Proteína , Bacterias Grampositivas , Pruebas de Sensibilidad MicrobianaRESUMEN
We herein report the selection and characterization of a new riboswitch dependent on the aminoglycoside tobramycin. Its dynamic range rivals even the tetracycline dependent riboswitch to be the current best performing, synthetic riboswitch that controls translation initiation. The riboswitch was selected with RNA Capture-SELEX, a method that not only selects for binding but also for structural changes in aptamers on binding. This study demonstrates how this method can fundamentally reduce the labour required for the de novo identification of synthetic riboswitches. The initially selected riboswitch candidate harbours two distinct tobramycin binding sites with KDs of 1.1 nM and 2.4 µM, respectively, and can distinguish between tobramycin and the closely related compounds kanamycin A and B. Using detailed genetic and biochemical analyses and 1H NMR spectroscopy, the proposed secondary structure of the riboswitch was verified and the tobramycin binding sites were characterized. The two binding sites were found to be essentially non-overlapping, allowing for a separate investigation of their contribution to the activity of the riboswitch. We thereby found that only the high-affinity binding site was responsible for regulatory activity, which allowed us to engineer a riboswitch from only this site with a minimal sequence size of 33 nt and outstanding performance.
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Aptámeros de Nucleótidos , Ingeniería Genética , Riboswitch , Tobramicina , Aptámeros de Nucleótidos/química , Ligandos , Conformación de Ácido Nucleico , Inhibidores de la Síntesis de la Proteína , ARN/química , Tetraciclina , Tobramicina/farmacología , Saccharomyces cerevisiae/efectos de los fármacos , Ingeniería Genética/métodosRESUMEN
INTRODUCTION: Streptococcal toxic shock syndrome (STSS) is a severe consequence of infections from Streptococcus pyogenes. The early identification and timely intervention with appropriate anti-infective agents are pivotal for managing pediatric STSS. This study evaluates the effectiveness of various treatment regimens for STSS in children. METHODS: Clinical data of children with STSS resulting from ß-hemolytic streptococcal infections in two hospitals were retrospectively analyzed from January 2009 to April 2023. Additionally, literature from the China National Knowledge Infrastructure on pediatric STSS was examined. Antimicrobial treatments were categorized into four groups based on their compositions, with an additional categorization for adjunct therapeutic drugs. RESULTS: Of 32 confirmed STSS cases, all displayed sensitivity to ampicillin, ß-lactam antibiotics, and vancomycin, but resistance to clindamycin, erythromycin, and tetracycline. From the literature, 23 studies with 50 cases were extracted, leading to a total of 82 patients for evaluation. The efficacy rates varied significantly among the four treatment groups. Notably, the standard penicillin-containing group exhibited the highest efficacy (86.4%), while the group with macrolides/unused antibiotics registered a 0% efficacy rate. The other two groups demonstrated efficacy rates of 32.1% and 42.3%. CONCLUSION: For pediatric STSS, Streptococcus pyogenes shows notable sensitivity to ampicillin. Implementing timely ß-lactam antibiotics, specifically penicillin, in conjunction with clindamycin and intravenous immunoglobulins enhances the treatment success rate.
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Choque Séptico , Infecciones Estreptocócicas , Humanos , Niño , Antibacterianos/uso terapéutico , Clindamicina/uso terapéutico , Choque Séptico/tratamiento farmacológico , Estudios Retrospectivos , Infecciones Estreptocócicas/tratamiento farmacológico , Streptococcus pyogenes , Penicilinas/uso terapéutico , Ampicilina/uso terapéutico , Inhibidores de la Síntesis de la Proteína/uso terapéutico , Macrólidos/uso terapéuticoRESUMEN
Streptococcus pneumoniae (pneumococcus) is a leading vaccine-preventable cause of childhood invasive disease. Nigeria has the second highest pneumococcal disease burden globally, with an estimated ~49â000 child deaths caused by pneumococcal infections each year. Ten-valent pneumococcal conjugate vaccine (GSK; PCV10) was introduced in December 2014 in a phased approach. However, few studies have characterized the disease-causing pneumococci from Nigeria. This study assessed the prevalence of serotypes, antibiotic susceptibility and genomic lineages using whole genome sequencing and identified lineages that could potentially escape PCV10 (GSK). We also investigated the potential differences in pneumococcal lineage features between children with and without sickle cell disease. A collection of 192 disease-causing pneumococcal isolates was obtained from Kano (n=189) and Abuja (n=3) states, Nigeria, between 1 January 2014 and 31 May 2018. The majority (99â%, 190/192) of specimens were recovered from children aged 5 years or under. Among them, 37 children had confirmed or traits of sickle cell disease. Our findings identified 25 serotypes expressed by 43 Global Pneumococcal Sequence Clusters (GPSCs) and 85 sequence types (STs). The most common serotypes were 14 (18â%, n=35), 6B (16â%, n=31), 1 (9â%, n=17), 5 (9â%, n=17) and 6A (9â%, n=17); all except serotype 6A are included in PCV10 (GSK). PCV10 (SII; PNEUMOSIL) and PCV13 formulations include serotypes 6A and 19A which would increase the overall coverage from 67â% by PCV10 (GSK) to 78 and 82â%, respectively. The pneumococcal lineages were a mix of globally spreading and unique local lineages. Following the use of PCV10 (GSK), GPSC5 expressing serotype 6A, GPSC10 (19A), GPSC26 (12F and 46) and GPSC627 (9L) are non-vaccine type lineages that could persist and potentially expand under vaccine-selective pressure. Approximately half (52â%, 99/192) of the pneumococcal isolates were resistant to the first-line antibiotic penicillin and 44â% (85/192) were multidrug-resistant. Erythromycin resistance was very low (2â%, 3/192). There was no significant difference in clinical manifestation, serotype prevalence or antibiotic resistance between children with and without traits of or confirmed sickle cell disease. In summary, our findings show that a high percentage of the pneumococcal disease were caused by the serotypes that are covered by currently available vaccines. Given the low prevalence of resistance, macrolide antibiotics, such as erythromycin, should be considered as an option to treat pneumococcal disease in Nigeria. However, appropriate use of macrolide antibiotics should be vigilantly monitored to prevent the potential increase in macrolide resistance.