Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 2.041
Filtrar
1.
Nano Lett ; 2024 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-39388580

RESUMO

Monolayer transition metal dichalcogenides (TMDs) have emerged as promising materials to generate single-photon emitters (SPEs). While there are several previous reports in the literature about TMD-based SPEs, the precise nature of the excitonic states involved in them is still under debate. Here, we use magneto-optical techniques under in-plane and out-of-plane magnetic fields to investigate the nature of SPEs in WSe2 monolayers on glass substrates under different strain profiles. Our results reveal important changes on the exciton localization and, consequently, on the optical properties of SPEs. Remarkably, we observe an anomalous PL energy redshift with no significant changes of photoluminescence (PL) intensity under an in-plane magnetic field. We present a model to explain this redshift based on intervalley defect excitons under a parallel magnetic field. Overall, our results offer important insights into the nature of SPEs in TMDs, which are valuable for future applications in quantum technologies.

2.
Clin Biochem ; 133-134: 110830, 2024 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-39353501

RESUMO

BACKGROUND: Glycated albumin (GA) is often described as a reflection of glucose exposure over the past 2-4 weeks. We examined the scale of the operative interval for changes in %GA from the perspective of a theoretical model for GA formation, by simulating the time course of changes in %GA after changes in glucose. METHODS: Probability of survival of albumin (A) was according to first-order elimination based on t1/2 of 17 days. Probability of formation of GA from A per unit time was proportional to glucose (G) and a glycation rate constant, k, deduced from reference values for %GA vs. G. We then simulated the kinetics of changes in %GA for conditions in which a prior steady-state (constant G) was followed by a step change in G. RESULTS: The glycation rate constant k was 9.79e-4/d/(mmol/L). We simulated changes in %GA for two scenarios involving step changes in G at time = 0: A. from 10 mmol/L to 15 mmol/L (%GA ultimately moves from 19.3% to 26.4%); B. from 15 mmol/L to 10 mmol/L (%GA ultimately moves from 26.4% to 19.3%). For both scenarios, the fractional transition of %GA between respective starting points and ultimate endpoints was after 30 days approximately 80% of the ultimate full transition. CONCLUSIONS: Model-based calculations support the description of %GA as a reflection of G over the past 4-6 weeks, longer than the period of 2-4 weeks that is commonly cited.

3.
Brain Behav Immun ; 2024 Oct 12.
Artigo em Inglês | MEDLINE | ID: mdl-39401554

RESUMO

BACKGROUND: Human endogenous retroviruses (HERVs) are sequences in the human genome that originated from infections with ancient retroviruses during our evolution. Previous studies have linked HERVs to neurodegenerative diseases, but defining their role in aetiology has been challenging. Here, we used a retrotranscriptome-wide association study (rTWAS) approach to assess the relationships between genetic risk for neurodegenerative diseases and HERV expression in the brain, calculated with genomic precision. METHODS: We analysed genetic association statistics pertaining to Alzheimer's disease, amyotrophic lateral sclerosis, multiple sclerosis, and Parkinson's disease, using HERV expression models calculated from 792 cortical samples. Robust risk factors were considered those that survived multiple testing correction in the primary analysis, which were also significant in conditional and joint analyses, and that had a posterior inclusion probability above 0.5 in fine-mapping analyses. RESULTS: The primary analysis identified 12 HERV expression signatures associated with neurodegenerative disease susceptibility. We found one HERV expression signature robustly associated with amyotrophic lateral sclerosis on chromosome 12q14 (MER61_12q14.2) and one robustly associated with multiple sclerosis on chromosome 1p36 (ERVLE_1p36.32a). A co-expression analysis suggested that these HERVs are involved in homophilic cell adhesion via plasma membrane adhesion molecules. CONCLUSIONS: We found HERV expression profiles robustly associated with amyotrophic lateral sclerosis and multiple sclerosis susceptibility, highlighting novel risk mechanisms underlying neurodegenerative disease, and offering potential new targets for therapeutic intervention.

4.
J Natl Cancer Inst ; 2024 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-39412492

RESUMO

PURPOSE: Most breast biopsies are diagnosed as benign breast disease (BBD), with 1.5- to fourfold increased breast cancer (BC) risk. Apart from pathologic diagnoses of atypical hyperplasia, few factors aid in BC risk assessment of these patients. We assessed whether a 313-SNP polygenic risk score (PRS) stratifies risk of BBD patients. PATIENTS AND METHODS: We pooled data from five Breast Cancer Association Consortium case-control studies (mean age = 59.9 years), including 6,706 cases and 8,488 controls. Using logistic regression, we estimated BC risk associations by self-reported BBD history and strata of PRS, with median PRS category among women without BBD as the referent. We assessed interactions and mediation of BBD and PRS with BC risk. RESULTS: BBD history was associated with increased BC risk (OR = 1.48, 95% CI: 1.37-1.60; p < .001). PRS increased BC risk, irrespective of BBD history (p-interaction = 0.48), with minimal evidence of mediation of either factor by the other. Women with BBD and PRS in the highest tertile had over 2-fold increased odds of BC (OR = 2.73, 95% CI: 2.41-3.09) and those with BBD and PRS in the lowest tertile experienced reduced BC risk (OR = 0.79, 95% CI: 0.70-0.91), compared to the reference group. Women with BBD and PRS in the highest decile had a 3.7- fold increase (95% CI: 3.00-4.61) compared to those with median PRS without BBD. CONCLUSION: BC risks are elevated among women with BBD and increase progressively with PRS, suggesting that optimal combinations of these factors may improve risk stratification.

5.
bioRxiv ; 2024 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-39386644

RESUMO

RNA binding proteins ( RBPs ) control varied processes, including RNA splicing, stability, transport, and translation 1-3 . Dysfunctional RNA-RBP interactions contribute to the pathogenesis of human disease 1,4,5 , however, characterizing the nature and dynamics of multiprotein assemblies on RNA has been challenging. To address this, non-isotopic ligation-based ultraviolet crosslinking immunoprecipitation 6 was combined with mass spectrometry ( irCLIP-RNP ) to identify RNA-dependent associated proteins ( RDAPs ) co-bound to RNA with any RBP of interest. irCLIP-RNP defined landscapes of multimeric protein assemblies on RNA, uncovering previously unknown patterns of RBP-RNA associations, including cell-type-selective combinatorial relationships between RDAPs and primary RBPs. irCLIP-RNP also defined dynamic RDAP remodeling in response to epidermal growth factor ( EGF ), uncovering EGF-induced recruitment of UPF1 adjacent to HNRNPC to effect splicing surveillance of cell proliferation mRNAs. To identify the RNAs simultaneously co-bound by multiple studied RBPs, a sequential immunoprecipitation irCLIP ( Re-CLIP ) method was also developed. Re-CLIP confirmed binding relationships seen in irCLIP-RNP and detected simultaneous HNRNPC and UPF1 co-binding on RND3 and DDX3X mRNAs. irCLIP-RNP and Re-CLIP provide a framework to identify and characterize dynamic RNA-protein assemblies in living cells.

6.
Prehosp Emerg Care ; : 1-5, 2024 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-39264840

RESUMO

Emergency Medical Services (EMS) and law enforcement (LE) frequently work as a team in encounters with individuals experiencing acute behavioral emergencies manifesting with severe agitation and aggression. The optimal management is a rehearsed, coordinated effort by law enforcement and EMS providing the necessary interventions to address behaviors that endanger the patient, the responders, and the public. The purpose of this document is to provide guidance and direction in the shared responsibility of managing and caring for a person displaying behavioral instability with irrational, agitated, and/or violent behavior. This is a discussion of the roles of law enforcement, 9-1-1 call centers (hereafter referred to as the Emergency Call Centers or "ECCs"), Fire, and EMS. A coordinated and unified response enhances the safety and effective management of potentially serious situations posed by individuals experiencing such acute behavioral emergencies. This paper provides the framework for an approach endorsed by NAEMSP, IACP, and the IAFC.

8.
Br J Cancer ; 2024 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-39294438

RESUMO

BACKGROUND: The clinical validity of the multifactorial BOADICEA model for epithelial tubo-ovarian cancer (EOC) risk prediction has not been assessed in a large sample size or over a longer term. METHODS: We evaluated the model discrimination and calibration in the UK Biobank cohort comprising 199,429 women (733 incident EOCs) of European ancestry without previous cancer history. We predicted 10-year EOC risk incorporating data on questionnaire-based risk factors (QRFs), family history, a 36-SNP polygenic risk score and pathogenic variants (PV) in six EOC susceptibility genes (BRCA1, BRCA2, RAD51C, RAD51D, BRIP1 and PALB2). RESULTS: Discriminative ability was maximised under the multifactorial model that included all risk factors (AUC = 0.68, 95% CI: 0.66-0.70). This model was well calibrated in deciles of predicted risk with calibration slope=0.99 (95% CI: 0.98-1.01). Discriminative ability was similar in women younger or older than 60 years. The AUC was higher when analyses were restricted to PV carriers (0.76, 95% CI: 0.69-0.82). Using relative risk (RR) thresholds, the full model classified 97.7%, 1.7%, 0.4% and 0.2% women in the RR < 2.0, 2.0 ≤ RR < 2.9, 2.9 ≤ RR < 6.0 and RR ≥ 6.0 categories, respectively, identifying 9.1 of incident EOC among those with RR ≥ 2.0. DISCUSSION: BOADICEA, implemented in CanRisk ( www.canrisk.org ), provides valid 10-year EOC risks and can facilitate clinical decision-making in EOC risk management.

9.
bioRxiv ; 2024 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-39282298

RESUMO

Protein aggregates are emerging therapeutic targets in rare monogenic causes of cardiomyopathy and amyloid heart disease, but their role in more prevalent heart failure syndromes remains mechanistically unexamined. We observed mis-localization of desmin and sarcomeric proteins to aggregates in human myocardium with ischemic cardiomyopathy and in mouse hearts with post-myocardial infarction ventricular remodeling, mimicking findings of autosomal-dominant cardiomyopathy induced by R120G mutation in the cognate chaperone protein, CRYAB. In both syndromes, we demonstrate increased partitioning of CRYAB phosphorylated on serine-59 to NP40-insoluble aggregate-rich biochemical fraction. While CRYAB undergoes phase separation to form condensates, the phospho-mimetic mutation of serine-59 to aspartate (S59D) in CRYAB mimics R120G-CRYAB mutants with reduced condensate fluidity, formation of protein aggregates and increased cell death. Conversely, changing serine to alanine (phosphorylation-deficient mutation) at position 59 (S59A) restored condensate fluidity, and reduced both R120G-CRYAB aggregates and cell death. In mice, S59D CRYAB knock-in was sufficient to induce desmin mis-localization and myocardial protein aggregates, while S59A CRYAB knock-in rescued left ventricular systolic dysfunction post-myocardial infarction and preserved desmin localization with reduced myocardial protein aggregates. 25-Hydroxycholesterol attenuated CRYAB serine-59 phosphorylation and rescued post-myocardial infarction adverse remodeling. Thus, targeting CRYAB phosphorylation-induced condensatopathy is an attractive strategy to counter ischemic cardiomyopathy.

10.
Curr Opin Biotechnol ; 90: 103197, 2024 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-39299060

RESUMO

Phosphorus (P) is essential for growing crops, but the supply of high-quality phosphate rock reserves used for fertilizer production is finite while losses of P from the food/waste system cause considerable environmental damage. A variety of emerging approaches in biotechnology are reviewed that hold promise for improving the sustainability of P use in the food/water systems. These include improved sensors, cell culture approaches to meat production, bio-based P adsorption and transformation strategies, advancements in understanding of polyphosphate-accumulating organisms, and new approaches involving biomineralization and anaerobic treatment. By advancing these technologies to scale, progress can be made in developing a circular phosphorus economy that improves food security while protecting drinking water and aquatic ecosystems.

11.
Psychol Med ; : 1-10, 2024 Sep 26.
Artigo em Inglês | MEDLINE | ID: mdl-39324397

RESUMO

BACKGROUND: Diagnostic criteria for major depressive disorder allow for heterogeneous symptom profiles but genetic analysis of major depressive symptoms has the potential to identify clinical and etiological subtypes. There are several challenges to integrating symptom data from genetically informative cohorts, such as sample size differences between clinical and community cohorts and various patterns of missing data. METHODS: We conducted genome-wide association studies of major depressive symptoms in three cohorts that were enriched for participants with a diagnosis of depression (Psychiatric Genomics Consortium, Australian Genetics of Depression Study, Generation Scotland) and three community cohorts who were not recruited on the basis of diagnosis (Avon Longitudinal Study of Parents and Children, Estonian Biobank, and UK Biobank). We fit a series of confirmatory factor models with factors that accounted for how symptom data was sampled and then compared alternative models with different symptom factors. RESULTS: The best fitting model had a distinct factor for Appetite/Weight symptoms and an additional measurement factor that accounted for the skip-structure in community cohorts (use of Depression and Anhedonia as gating symptoms). CONCLUSION: The results show the importance of assessing the directionality of symptoms (such as hypersomnia versus insomnia) and of accounting for study and measurement design when meta-analyzing genetic association data.

12.
J Community Genet ; 2024 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-39320563

RESUMO

BACKGROUND: Multifactorial cancer risk prediction tools, such as CanRisk, are increasingly being incorporated into routine healthcare. Understanding risk information and communicating risk is challenging and healthcare professionals rely substantially on the outputs of risk prediction tools to communicate results. This work aimed to produce a new CanRisk report so users can directly access key information and communicate risk estimates effectively. METHODS: Over a 13-month period, we led an 8-step co-design process with patients, the public, and healthcare professionals. Steps comprised 1) think aloud testing of the original CanRisk report; 2) structured feedback on the original report; 3) literature review; 4) development of a new report prototype; 5) first round of structured feedback; 6) updating the new report prototype; 7) second round of structured feedback; and 8) finalising and publishing the new CanRisk report. RESULTS: We received 56 sets of feedback from 34 stakeholders. Overall, the original CanRisk report was not suitable for patients and the public. Building on the feedback, the new report has an overview of the information presented: section one summarises key information for individuals; sections two and three present information for healthcare professionals in different settings. New features also include explanatory text, definitions, graphs, keys and tables to support the interpretation of the information. DISCUSSION: This co-design experience shows the value of collaboration for the successful communication of complex health information. As a result, the new CanRisk report has the potential to better support shared decision-making processes about cancer risk management across clinical settings.

13.
Aging Cell ; 23(10): e14288, 2024 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-39092674

RESUMO

Reactivation of retroelements in the human genome has been linked to aging. However, whether the epigenetic state of specific retroelements can predict chronological age remains unknown. We provide evidence that locus-specific retroelement DNA methylation can be used to create retroelement-based epigenetic clocks that accurately measure chronological age in the immune system, across human tissues, and pan-mammalian species. We also developed a highly accurate retroelement epigenetic clock compatible with EPICv.2.0 data that was constructed from CpGs that did not overlap with existing first- and second-generation epigenetic clocks, suggesting a unique signal for epigenetic clocks not previously captured. We found retroelement-based epigenetic clocks were reversed during transient epigenetic reprogramming, accelerated in people living with HIV-1, and responsive to antiretroviral therapy. Our findings highlight the utility of retroelement-based biomarkers of aging and support a renewed emphasis on the role of retroelements in geroscience.


Assuntos
Envelhecimento , Metilação de DNA , Epigênese Genética , Retroelementos , Humanos , Metilação de DNA/genética , Retroelementos/genética , Envelhecimento/genética , Biomarcadores/metabolismo , Animais , Masculino , Feminino , Pessoa de Meia-Idade , Idoso , Adulto
14.
J Clin Med ; 13(16)2024 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-39200793

RESUMO

Background: Biomechanical analysis of the sagittal alignment of the lumbar spine and pelvis on radiographs is common in clinical practices including chiropractic, physical therapy, scoliosis-related thoraco-lumbo-sacral orthosis (TLSO) management, orthopedics, and neurosurgery. Of specific interest is the assessment of pelvic morphology and the relationship between angle of pelvic incidence, sacral slope, and lumbar lordosis to pain, disability, and clinical treatment of spine conditions. The current state of the literature on the reliability of common methods quantifying these parameters on radiographs is limited. Methods: The objective of this systematic review is to identify and review the available studies on the reliability of different methods of biomechanical analysis of sagittal lumbo-pelvic parameters used in clinical practice. Our review followed the recommendations of the preferred reporting items for systematic reviews and meta-analyses (PRISMA). The design of this systematic review was registered with PROSPERO (CRD42023379873). Results: The search strategy yielded a total of 2387 articles. A total of 1539 articles were screened after deduplication and exclusion by automation tools, leaving 473 full-text articles that were retrieved. After exclusion, 64 articles met the inclusion criteria. The preponderance of the evidence showed good to excellent reliability for biomechanical assessment of sagittal lumbo-pelvic spine alignment. Conclusions: The results of this systematic review of the literature show that sagittal radiographic analysis of spinal biomechanics and alignment of the human lumbo-pelvic spine is a reliable tool for aiding diagnosis and management in clinical settings.

15.
J Med Genet ; 2024 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-39209703

RESUMO

BACKGROUND: Deleterious germline variants in ATM and CHEK2 have been associated with a moderately increased risk of breast cancer. Risks for other cancers remain unclear. METHODS: Cancer associations for coding variants in ATM and CHEK2 were evaluated using whole-exome sequence data from UK Biobank linked to cancer registration data (348 488 participants), and analysed both as a retrospective case-control and a prospective cohort study. Odds ratios, hazard ratios, and combined relative risks (RRs) were estimated by cancer type and gene. Separate analyses were performed for protein-truncating variants (PTVs) and rare missense variants (rMSVs; allele frequency <0.1%). RESULTS: PTVs in ATM were associated with increased risks of nine cancers at p<0.001 (pancreas, oesophagus, lung, melanoma, breast, ovary, prostate, bladder, lymphoid leukaemia (LL)), and three at p<0.05 (colon, diffuse non-Hodgkin's lymphoma (DNHL), rectosigmoid junction). Carriers of rMSVs had increased risks of four cancers (p<0.05: stomach, pancreas, prostate, Hodgkin's disease (HD)). RRs were highest for breast, prostate, and any cancer where rMSVs lay in the FAT or PIK domains, and had a Combined Annotation Dependent Depletion score in the highest quintile.PTVs in CHEK2 were associated with three cancers at p<0.001 (breast, prostate, HD) and six at p<0.05 (oesophagus, melanoma, ovary, kidney, DNHL, myeloid leukaemia). Carriers of rMSVs had increased risks of five cancers (p<0.001: breast, prostate, LL; p<0.05: melanoma, multiple myeloma). CONCLUSION: PTVs in ATM and CHEK2 are associated with a wide range of cancers, with the highest RR for pancreatic cancer in ATM PTV carriers. These findings can inform genetic counselling of carriers.

16.
Mol Pharmacol ; 2024 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-39214710

RESUMO

The γ-aminobutyric acid type A (GABAA) receptor is modulated by a number of neuroactive steroids. Sulfated steroids and 3ß-hydroxy steroids inhibit while 3α-hydroxy steroids typically potentiate the receptor. Here, we have investigated inhibition of the α1ß3γ2L GABAA receptor by the endogenous neurosteroid 3α-hydroxy-5ß-pregnan-20-one (3α5ßP) and the synthetic neuroactive steroid 3α-hydroxy-5α-androstane-17ß-carbonitrile (ACN). The receptors were expressed in Xenopus oocytes. All experiments were done using two-electrode voltage-clamp electrophysiology. In the presence of low concentrations of GABA, 3α5ßP and ACN potentiate the GABAA receptor. To reveal inhibition, we conducted the experiments on receptors activated by the combination of a saturating concentration of GABA and propofol to fully activate the receptors and mask potentiation, or on mutant receptors in which potentiation is ablated. Under these conditions, both steroids inhibited the receptor with IC50s of ~13 µM and maximal inhibitory effects of 70-90%. Receptor inhibition by 3α5ßP was sensitive to substitution of the α1TM2-2' residue, previously shown to ablate inhibition by pregnenolone sulfate. However, results of coapplication studies and the apparent lack of state dependence suggest that pregnenolone sulfate and 3α5ßP inhibit the GABAA receptor independently and through distinct mechanisms. Mutations to the neurosteroid binding sites in the α1 and ß3 subunits significantly, albeit weakly and incompletely, reduced inhibition by 3α5ßP and ACN. Significance Statement The heteromeric GABAA receptor is inhibited by sulfated steroids and 3ß-hydroxy steroids while 3α-hydroxy steroids are considered to potentiate the receptor. We show here that 3α-hydroxy steroids have inhibitory effects on the α1ß3γ2L receptor, which are observed in specific experimental settings and are expected to manifest under different physiological conditions.

17.
Int J Mol Sci ; 25(16)2024 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-39201544

RESUMO

5ß-Dihydrosteroids are produced by the reduction of Δ4-3-ketosteroids catalyzed by steroid 5ß-reductase (AKR1D1). By analogy with steroid 5α-reductase, genetic deficiency exists in AKR1D1 which leads to errors in newborn metabolism and in this case to bile acid deficiency. Also, like the 5α-dihydrosteroids (e.g., 5α-dihydrotestosterone), the 5ß-dihydrosteroids produced by AKR1D1 are not inactive but regulate ligand access to nuclear receptors, can act as ligands for nuclear and membrane-bound receptors, and regulate ion-channel opening. For example, 5ß-reduction of cortisol and cortisone yields the corresponding 5ß-dihydroglucocorticoids which are inactive on the glucocorticoid receptor (GR) and provides an additional mechanism of pre-receptor regulation of ligands for the GR in liver cells. By contrast, 5ß-pregnanes can act as neuroactive steroids at the GABAA and NMDA receptors and at low-voltage-activated calcium channels, act as tocolytic agents, have analgesic activity and act as ligands for PXR, while bile acids act as ligands for FXR and thereby control cholesterol homeostasis. The 5ß-androstanes also have potent vasodilatory properties and work through blockade of Ca2+ channels. Thus, a preference for 5ß-dihydrosteroids to work at the membrane level exists via a variety of mechanisms. This article reviews the field and identifies gaps in knowledge to be addressed in future research.


Assuntos
Ácidos e Sais Biliares , Humanos , Animais , Ácidos e Sais Biliares/metabolismo , Oxirredutases/metabolismo
18.
bioRxiv ; 2024 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-39091845

RESUMO

Sterol transport proteins (STPs) play a pivotal role in cholesterol homeostasis and therefore are essential for healthy human physiology. Despite recent advances in dissecting functions of STPs in the human cell, there is still a significant knowledge gap regarding their specific biological functions and a lack of suitable selective probes for their study. Here, we profile fluorescent steroid-based probes across ten STPs, uncovering substantial differences in their selectivity, aiding the retrospective and prospective interpretation of biological results generated with those probes. These results guided the establishment of an STP screening panel combining diverse biophysical assays, enabling the evaluation of 41 steroid-based natural products and derivatives. Combining this with a thorough structural analysis revealed the molecular basis for STP specific selectivity profiles, leading to the uncovering of several new potent and selective Aster-B inhibitors, and supporting the role of this protein in steroidogenesis.

20.
Br J Pharmacol ; 181(21): 4229-4244, 2024 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-38978389

RESUMO

BACKGROUND AND PURPOSE: Neurosteroids are allosteric modulators of GABAA currents, acting through several functional binding sites although their affinity and specificity for each site are unknown. The goal of this study was to measure steady-state binding affinities of various neurosteroids for specific sites on the GABAA receptor. EXPERIMENTAL APPROACH: Two methods were developed to measure neurosteroid binding affinity: (1) quenching of specific tryptophan residues in neurosteroid binding sites by the neurosteroid 17-methylketone group, and (2) FRET between MQ290 (an intrinsically fluorescent neurosteroid) and tryptophan residues in the binding sites. The assays were developed using ELIC-α1GABAAR, a chimeric receptor containing transmembrane domains of the α1-GABAA receptor. Tryptophan mutagenesis was used to identify specific interactions. KEY RESULTS: Allopregnanolone (3α-OH neurosteroid) was shown to bind at intersubunit and intrasubunit sites with equal affinity, whereas epi-allopregnanolone (3ß-OH neurosteroid) binds at the intrasubunit site. MQ290 formed a strong FRET pair with W246, acting as a site-specific probe for the intersubunit site. The affinity and site-specificity of several neurosteroid agonists and inverse agonists was measured using the MQ290 binding assay. The FRET assay distinguishes between competitive and allosteric inhibition of MQ290 binding and demonstrated an allosteric interaction between the two neurosteroid binding sites. CONCLUSIONS AND IMPLICATIONS: The affinity and specificity of neurosteroid binding to two sites in the ELIC-α1GABAAR were directly measured and an allosteric interaction between the sites was revealed. Adaptation of the MQ290 FRET assay to a plate-reader format will enable screening for high affinity agonists and antagonists for neurosteroid binding sites.


Assuntos
Neuroesteroides , Receptores de GABA-A , Receptores de GABA-A/metabolismo , Receptores de GABA-A/química , Receptores de GABA-A/genética , Sítios de Ligação , Neuroesteroides/metabolismo , Animais , Pregnanolona/farmacologia , Pregnanolona/metabolismo , Humanos , Transferência Ressonante de Energia de Fluorescência , Xenopus laevis , Ligação Proteica
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...