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1.
Nat Commun ; 15(1): 3544, 2024 May 13.
Artículo en Inglés | MEDLINE | ID: mdl-38740791

RESUMEN

G-protein-coupled receptors (GPCRs) play pivotal roles in various physiological processes. These receptors are activated to different extents by diverse orthosteric ligands and allosteric modulators. However, the mechanisms underlying these variations in signaling activity by allosteric modulators remain largely elusive. Here, we determine the three-dimensional structure of the µ-opioid receptor (MOR), a class A GPCR, in complex with the Gi protein and an allosteric modulator, BMS-986122, using cryogenic electron microscopy. Our results reveal that BMS-986122 binding induces changes in the map densities corresponding to R1673.50 and Y2545.58, key residues in the structural motifs conserved among class A GPCRs. Nuclear magnetic resonance analyses of MOR in the absence of the Gi protein reveal that BMS-986122 binding enhances the formation of the interaction between R1673.50 and Y2545.58, thus stabilizing the fully-activated conformation, where the intracellular half of TM6 is outward-shifted to allow for interaction with the Gi protein. These findings illuminate that allosteric modulators like BMS-986122 can potentiate receptor activation through alterations in the conformational dynamics in the core region of GPCRs. Together, our results demonstrate the regulatory mechanisms of GPCRs, providing insights into the rational development of therapeutics targeting GPCRs.


Asunto(s)
Microscopía por Crioelectrón , Receptores Opioides mu , Receptores Opioides mu/metabolismo , Receptores Opioides mu/química , Receptores Opioides mu/genética , Regulación Alostérica , Humanos , Unión Proteica , Subunidades alfa de la Proteína de Unión al GTP Gi-Go/metabolismo , Subunidades alfa de la Proteína de Unión al GTP Gi-Go/química , Subunidades alfa de la Proteína de Unión al GTP Gi-Go/genética , Células HEK293 , Ligandos , Modelos Moleculares , Conformación Proteica
2.
Nat Commun ; 14(1): 4977, 2023 08 28.
Artículo en Inglés | MEDLINE | ID: mdl-37640715

RESUMEN

Many RNA viruses employ internal ribosome entry sites (IRESs) in their genomic RNA to commandeer the host's translational machinery for replication. The IRES from encephalomyocarditis virus (EMCV) interacts with eukaryotic translation initiation factor 4 G (eIF4G), recruiting the ribosomal subunit for translation. Here, we analyze the three-dimensional structure of the complex composed of EMCV IRES, the HEAT1 domain fragment of eIF4G, and eIF4A, by cryo-electron microscopy. Two distinct eIF4G-interacting domains on the IRES are identified, and complex formation changes the angle therebetween. Further, we explore the dynamics of these domains by using solution NMR spectroscopy, revealing conformational equilibria in the microsecond to millisecond timescale. In the lowly-populated conformations, the base-pairing register of one domain is shifted with the structural transition of the three-way junction, as in the complex structure. Our study provides insights into the viral RNA's sophisticated strategy for optimal docking to hijack the host protein.


Asunto(s)
Factor 4G Eucariótico de Iniciación , ARN Viral , ARN Viral/genética , Microscopía por Crioelectrón , Virus de la Encefalomiocarditis/genética , Genómica , Sitios Internos de Entrada al Ribosoma
3.
BMJ Open ; 13(8): e073846, 2023 08 24.
Artículo en Inglés | MEDLINE | ID: mdl-37620273

RESUMEN

INTRODUCTION: Cardiac rehabilitation (CR) is strongly recommended as a medical treatment to improve the prognosis and quality of life of patients with heart failure (HF); however, participation rates in CR are low compared with other evidence-based treatments. One reason for this is the geographical distance between patients' homes and hospitals. To address this issue, we developed an integrated telerehabilitation platform, RH-01, for home-based CR. We hypothesised that using the RH-01 platform for home-based CR would demonstrate non-inferiority compared with traditional centre-based CR. METHODS AND ANALYSIS: The E-REHAB trial aims to evaluate the efficacy and safety of RH-01 for home-based CR compared with traditional centre-based CR for patients with HF. This clinical trial will be conducted under a prospective, randomised, controlled and non-inferiority design with a primary focus on HF patients. Further, to assess the generalisability of the results in HF to other cardiovascular disease (CVD), the study will also include patients with other CVDs. The trial will enrol 108 patients with HF and 20 patients with other CVD. Eligible HF patients will be randomly assigned to either traditional centre-based CR or home-based CR in a 1:1 fashion. Patients with other CVDs will not be randomised, as safety assessment will be the primary focus. The intervention group will receive a 12-week programme conducted two or three times per week consisting of a remotely supervised home-based CR programme using RH-01, while the control group will receive a traditional centre-based CR programme. The primary endpoint of this trial is change in 6 min walk distance. ETHICS AND DISSEMINATION: The conduct of the study has been approved by an institutional review board at each participating site, and all patients will provide written informed consent before entry. The report of the study will be disseminated via scientific fora, including peer-reviewed publications and presentations at conferences. TRIAL REGISTRATION NUMBER: jRCT:2052200064.


Asunto(s)
Rehabilitación Cardiaca , Enfermedades Cardiovasculares , Insuficiencia Cardíaca , Telerrehabilitación , Humanos , Estudios Prospectivos , Calidad de Vida , Ensayos Clínicos Controlados Aleatorios como Asunto
4.
ACS Omega ; 8(27): 24544-24551, 2023 Jul 11.
Artículo en Inglés | MEDLINE | ID: mdl-37457453

RESUMEN

We aimed to develop a platform to rapidly investigate the responses of agonists and antagonists to G-protein-coupled receptors (GPCRs) using native mass spectrometry (MS). We successfully observed the ligand-bound human ß2 adrenergic receptor (hß2AR); however, it was challenging to quantitatively discuss drug efficacy from MS data alone. Since ligand-bound GPCRs are stabilized by the Gα subunit of G proteins on the membrane, mini-Gs and nanobody80 (Nb80) that can mimic the Gα interface of the GPCR were utilized. Ternary complexes of hß2AR, ligand, and mini-Gs or Nb80 were prepared and subjected to native MS. We found a strong correlation between the hß2AR-mini-Gs or -Nb80 complex ratio observed in the mass spectra and agonist/antagonist efficacy obtained using a cell-based assay. This method does not require radioisotope labeling and would be applicable to the analysis of other GPCRs, facilitating the characterization of candidate compounds as GPCR agonists and antagonists.

5.
Cureus ; 15(4): e37757, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-37213944

RESUMEN

A 64-year-old man was referred from a local clinic with a chief complaint of cough. Computed tomography (CT) revealed a mass comprising a tumor in the right lower lobe and enlarged mediastinal lymph nodes, and a whole-body workup with positron emission tomography-CT showed bilateral lymph node enlargement and cancerous pericarditis. Biopsy with bronchoscopy of the right lower lobe tumor and mediastinal lymph node confirmed the histological findings of small cell lung carcinoma. The clinical diagnosis of extensive-stage small cell lung cancer (ES-SCLC) was confirmed, and first-line treatment with carboplatin, etoposide, and atezolizumab was initiated, followed by tri-weekly atezolizumab thrice. The patient experienced worsening pleural effusion treated with thoracentesis, pleural drainage, and pleurodesis. He also experienced several recurrences, which were managed with second and third-line chemotherapy with nogitecan and amrubicin. He has been receiving third-line therapy for over 30 months since his initial visit and remains stable as of today. The patient experienced an exceptional treatment outcome considering that the prognosis of ES-SCLC remains poor, with a median survival of approximately 10 months with conventional chemotherapies using cytotoxic agents. The use of immune checkpoint inhibitors (ICI) for ES-SCLC as first-line treatment may demonstrate a persistent antitumor effect, and result in improved survival following discontinuation. In conclusion, therapy including ICI for patients with ES-SCLC is a treatment option that shows possibilities in improving survival even after discontinuation.

6.
Front Cardiovasc Med ; 10: 1127121, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37077746

RESUMEN

Background: This study compares the efficacy of coronary computed tomography angiography (CCTA) and near-infrared spectroscopy intravascular ultrasound (NIRS-IVUS) in patients with significant coronary stenosis for predicting periprocedural myocardial injury during percutaneous coronary intervention (PCI). Methods: We prospectively enrolled 107 patients who underwent CCTA before PCI and performed NIRS-IVUS during PCI. Based on the maximal lipid core burden index for any 4-mm longitudinal segments (maxLCBI4mm) in the culprit lesion, we divided the patients into two groups: lipid-rich plaque (LRP) group (maxLCBI4mm ≥ 400; n = 48) and no-LRP group (maxLCBI4mm < 400; n = 59). Periprocedural myocardial injury was a postprocedural cardiac troponin T (cTnT) elevation of ≥5 times the upper limit of normal. Results: The LRP group had a significantly higher cTnT (p = 0.026), lower CT density (p < 0.001), larger percentage atheroma volume (PAV) by NIRS-IVUS (p = 0.036), and larger remodeling index measured by both CCTA (p = 0.020) and NIRS-IVUS (p < 0.001). A significant negative linear correlation was found between maxLCBI4mm and CT density (rho = -0.552, p < 0.001). Multivariable logistic regression analysis identified maxLCBI4mm [odds ratio (OR): 1.006, p = 0.003] and PAV (OR: 1.125, p = 0.014) as independent predictors of periprocedural myocardial injury, while CT density was not an independent predictor (OR: 0.991, p = 0.22). Conclusion: CCTA and NIRS-IVUS correlated well to identify LRP in culprit lesions. However, NIRS-IVUS was more competent in predicting the risk of periprocedural myocardial injury.

7.
Proc Natl Acad Sci U S A ; 119(16): e2121918119, 2022 04 19.
Artículo en Inglés | MEDLINE | ID: mdl-35412886

RESUMEN

Allosteric modulators of G-protein-coupled receptors (GPCRs) enhance signaling by binding to GPCRs concurrently with their orthosteric ligands, offering a novel approach to overcome the efficacy limitations of conventional orthosteric ligands. However, the structural mechanism by which allosteric modulators mediate GPCR signaling remains largely unknown. Here, to elucidate the mechanism of µ-opioid receptor (MOR) activation by allosteric modulators, we conducted solution NMR analyses of MOR by monitoring the signals from methionine methyl groups. We found that the intracellular side of MOR exists in an equilibrium between three conformations with different activities. Interestingly, the populations in the equilibrium determine the apparent signaling activity of MOR. Our analyses also revealed that the equilibrium is not fully shifted to the conformation with the highest activity even in the full agonist-bound state, where the intracellular half of TM6 is outward-shifted. Surprisingly, an allosteric modulator for MOR, BMS-986122, shifted the equilibrium toward the conformation with the highest activity, leading to the increased activity of MOR in the full agonist-bound state. We also determined that BMS-986122 binds to a cleft in the transmembrane region around T162 on TM3. Together, these results suggest that BMS-986122 binding to TM3 increases the activity of MOR by rearranging the direct interactions of TM3 and TM6, thus stabilizing TM6 in the outward-shifted position which is favorable for G-protein binding. These findings shed light on the rational developments of novel allosteric modulators that activate GPCRs further than orthosteric ligands alone and pave the way for next-generation GPCR-targeting therapeutics.


Asunto(s)
Receptores Opioides mu , Sulfonas , Regulación Alostérica , Sitio Alostérico , Sitios de Unión , Ligandos , Conformación Proteica/efectos de los fármacos , Receptores Opioides mu/agonistas , Receptores Opioides mu/química , Transducción de Señal , Sulfonas/química , Sulfonas/farmacología
8.
J Biol Chem ; 298(5): 101844, 2022 05.
Artículo en Inglés | MEDLINE | ID: mdl-35307347

RESUMEN

Eukaryotic mRNAs possess a poly(A) tail at their 3'-end, to which poly(A)-binding protein C1 (PABPC1) binds and recruits other proteins that regulate translation. Enhanced poly(A)-dependent translation, which is also PABPC1 dependent, promotes cellular and viral proliferation. PABP-interacting protein 2A (Paip2A) effectively represses poly(A)-dependent translation by causing the dissociation of PABPC1 from the poly(A) tail; however, the underlying mechanism remains unknown. This study was conducted to investigate the functional mechanisms of Paip2A action by characterizing the PABPC1-poly(A) and PABPC1-Paip2A interactions. Isothermal titration calorimetry and NMR analyses indicated that both interactions predominantly occurred at the RNA recognition motif (RRM)2-RRM3 regions of PABPC1, which have comparable affinities for poly(A) and Paip2A (dissociation constant, Kd = 1 nM). However, the Kd values of isolated RRM2 were 200 and 4 µM in their interactions with poly(A) and Paip2A, respectively; Kd values of 5 and 1 µM were observed for the interactions of isolated RRM3 with poly(A) and Paip2A, respectively. NMR analyses also revealed that Paip2A can bind to the poly(A)-binding interfaces of the RRM2 and RRM3 regions of PABPC1. Based on these results, we propose the following functional mechanism for Paip2A: Paip2A initially binds to the RRM2 region of poly(A)-bound PABPC1, and RRM2-anchored Paip2A effectively displaces the RRM3 region from poly(A), resulting in dissociation of the whole PABPC1 molecule. Together, our findings provide insight into the translation repression effect of Paip2A and may aid in the development of novel anticancer and/or antiviral drugs.


Asunto(s)
Poli A , Proteínas de Unión a Poli(A) , Biosíntesis de Proteínas , Motivo de Reconocimiento de ARN , Poli A/metabolismo , Proteínas de Unión a Poli(A)/genética , Proteínas de Unión a Poli(A)/metabolismo , Unión Proteica , ARN Mensajero/genética , Proteínas de Unión al ARN/genética , Proteínas de Unión al ARN/metabolismo
9.
J Magn Reson ; 336: 107164, 2022 03.
Artículo en Inglés | MEDLINE | ID: mdl-35168190

RESUMEN

G protein-coupled receptors (GPCRs) include various neurotransmitters and hormones, and over 30% of modern drugs target GPCRs. The number of GPCR crystal structures has rapidly increased, and many structures of GPCRs in complexes with their binding partners are being solved by cryo-electron microscopy. However, crystallographic or cryo-electron microscopy data alone cannot fully explain the important features of GPCR signaling determined experimentally. Recent studies have suggested that GPCRs are structurally dynamic, and exchange between multiple conformations. In this respect, NMR methods provide information about the dynamics of proteins over a wide range of frequencies, in aqueous solutions at nearphysiological temperatures. Although NMR studies of GPCRs are challenging due to their innate instability and relatively large molecular weights, recent methodological advances have enabled us to observe the NMR signals of various GPCRs. These NMR studies revealed that GPCRs exist in function-related equilibria between locally different conformations that are simultaneously populated. Here we will describe solution NMR studies that have clarified the function-related conformational dynamics of two GPCRs, ß2 adrenergic receptor and adenosine A2A receptor.


Asunto(s)
Receptores Acoplados a Proteínas G , Microscopía por Crioelectrón/métodos , Espectroscopía de Resonancia Magnética/métodos , Conformación Molecular , Receptores Acoplados a Proteínas G/química , Receptores Acoplados a Proteínas G/metabolismo
10.
IJU Case Rep ; 4(6): 386-390, 2021 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-34755064

RESUMEN

INTRODUCTION: The combination of pembrolizumab and axitinib has recently been approved as a first-line treatment for previously untreated metastatic renal cell carcinoma. However, immune-related adverse events are not well known. CASE PRESENTATION: A 65-year-old male was diagnosed with renal cell carcinoma with metastases to the brain and lungs. The patient had a medical history of stasis dermatitis. During the combined treatment of pembrolizumab and axitinib, blisters appeared on the lower extremities. Skin biopsy revealed septal panniculitis, pustules, and perivascular lymphocytic and neutrophilic infiltration of the skin, and the patient was diagnosed with immune-related dermatitis. The dermatitis improved with oral prednisolone treatment. CONCLUSION: A case of immune-related dermatitis during combinatorial treatment with pembrolizumab and axitinib for renal cell carcinoma has been reported. Preexisting stasis dermatitis may have affected the onset and deterioration of immune-related dermatitis.

11.
Membranes (Basel) ; 11(8)2021 Aug 09.
Artículo en Inglés | MEDLINE | ID: mdl-34436367

RESUMEN

A primary biological function of multi-spanning membrane proteins is to transfer information and/or materials through a membrane by changing their conformations. Therefore, particular dynamics of the membrane proteins are tightly associated with their function. The semi-atomic resolution dynamics information revealed by NMR is able to discriminate function-related dynamics from random fluctuations. This review will discuss several studies in which quantitative dynamics information by solution NMR has contributed to revealing the structural basis of the function of multi-spanning membrane proteins, such as ion channels, GPCRs, and transporters.

12.
Int J Clin Oncol ; 26(10): 1955-1960, 2021 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-34136964

RESUMEN

PURPOSE: To assess the surgical outcomes of off-clamp open partial nephrectomy without renorrhaphy. In the era of robot-assisted surgeries, open partial nephrectomy remains a surgical option for ≥ T1b renal tumours. Although the necessity of renal pedicle clamping and renorrhaphy in open partial nephrectomy for larger tumours remains to be discussed, reports on this issue are rare. METHODS: Twenty-seven open partial nephrectomies for ≥ T1b renal tumours were performed without renal pedicle clamping or renorrhaphy. A soft coagulation system was used to control bleeding from the resection bed. Surgical results, complications, and predictors of perioperative estimated glomerular filtration rate (eGFR) preservation at 1 month and 3 months after surgery were analysed. RESULTS: The median estimated volume of blood loss was 420 mL. The rates of perioperative eGFR preservation were 88.9 and 87.3% at 1 and 3 months after surgery, respectively. Tumour size was an independent predictor of perioperative eGFR preservation at 1 month after surgery, whereas age and exophytic/endophytic properties of the tumour were independent predictors of perioperative eGFR preservation at 3 months after surgery. CONCLUSION: Open partial nephrectomy without renal pedicle clamping or renorrhaphy could be safely performed for ≥ T1b renal tumours, even when tumours were entirely endophytic and located close to the renal pedicle. Mild perioperative eGFR reduction was observed. Although surgical indications should be carefully considered in these cases, off-clamp open partial nephrectomy without renorrhaphy is a feasible procedure for patients with ≥ T1b renal tumours.


Asunto(s)
Neoplasias Renales , Procedimientos Quirúrgicos Robotizados , Tasa de Filtración Glomerular , Humanos , Riñón/cirugía , Neoplasias Renales/cirugía , Nefrectomía , Estudios Retrospectivos , Resultado del Tratamiento
13.
Intern Med ; 60(15): 2445-2449, 2021 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-33642481

RESUMEN

Fusobacterium necrophorum is a very rare cause of endocarditis. We herein report a case of F. necrophorum endocarditis with liver abscesses in a 51-year-old woman. This is the first reported case of monomicrobial F. necrophorum endocarditis to present in a patient over 50 years old. We also reviewed 10 reported cases, including the present case. Our review indicated that anaerobic bacteria, including Gram-negative anaerobic bacilli such as F. necrophorum, should be considered in the differential diagnosis of infective endocarditis, especially in patients without preexisting organic heart disease.


Asunto(s)
Endocarditis Bacteriana , Endocarditis , Infecciones por Fusobacterium , Absceso Hepático , Endocarditis/complicaciones , Endocarditis/diagnóstico , Endocarditis Bacteriana/complicaciones , Endocarditis Bacteriana/diagnóstico , Femenino , Infecciones por Fusobacterium/complicaciones , Infecciones por Fusobacterium/diagnóstico , Fusobacterium necrophorum , Humanos , Persona de Mediana Edad
14.
BMC Mol Cell Biol ; 22(1): 3, 2021 Jan 07.
Artículo en Inglés | MEDLINE | ID: mdl-33413079

RESUMEN

BACKGROUND: Human ether-à-go-go-related gene potassium channel 1 (hERG) is a voltage-gated potassium channel, the voltage-sensing domain (VSD) of which is targeted by a gating-modifier toxin, APETx1. APETx1 is a 42-residue peptide toxin of sea anemone Anthopleura elegantissima and inhibits hERG by stabilizing the resting state. A previous study that conducted cysteine-scanning analysis of hERG identified two residues in the S3-S4 region of the VSD that play important roles in hERG inhibition by APETx1. However, mutational analysis of APETx1 could not be conducted as only natural resources have been available until now. Therefore, it remains unclear where and how APETx1 interacts with the VSD in the resting state. RESULTS: We established a method for preparing recombinant APETx1 and determined the NMR structure of the recombinant APETx1, which is structurally equivalent to the natural product. Electrophysiological analyses using wild type and mutants of APETx1 and hERG revealed that their hydrophobic residues, F15, Y32, F33, and L34, in APETx1, and F508 and I521 in hERG, in addition to a previously reported acidic hERG residue, E518, play key roles in the inhibition of hERG by APETx1. Our hypothetical docking models of the APETx1-VSD complex satisfied the results of mutational analysis. CONCLUSIONS: The present study identified the key residues of APETx1 and hERG that are involved in hERG inhibition by APETx1. These results would help advance understanding of the inhibitory mechanism of APETx1, which could provide a structural basis for designing novel ligands targeting the VSDs of KV channels.


Asunto(s)
Venenos de Cnidarios/toxicidad , Canal de Potasio ERG1/metabolismo , Activación del Canal Iónico/efectos de los fármacos , Secuencia de Aminoácidos , Animales , Venenos de Cnidarios/química , Venenos de Cnidarios/genética , Análisis Mutacional de ADN , Células HEK293 , Humanos , Concentración de Iones de Hidrógeno , Interacciones Hidrofóbicas e Hidrofílicas , Modelos Moleculares , Simulación del Acoplamiento Molecular , Proteínas Mutantes/metabolismo , Mutación/genética , Proteínas Recombinantes/toxicidad , Soluciones , Xenopus laevis
15.
Nat Commun ; 11(1): 5168, 2020 10 14.
Artículo en Inglés | MEDLINE | ID: mdl-33057011

RESUMEN

The potassium ion (K+) channel plays a fundamental role in controlling K+ permeation across the cell membrane and regulating cellular excitabilities. Mutations in the transmembrane pore reportedly affect the gating transitions of K+ channels, and are associated with the onset of neural disorders. However, due to the lack of structural and dynamic insights into the functions of K+ channels, the structural mechanism by which these mutations cause K+ channel dysfunctions remains elusive. Here, we used nuclear magnetic resonance spectroscopy to investigate the structural mechanism underlying the decreased K+-permeation caused by disease-related mutations, using the prokaryotic K+ channel KcsA. We demonstrated that the conformational equilibrium in the transmembrane region is shifted toward the non-conductive state with the closed intracellular K+-gate in the disease-related mutant. We also demonstrated that this equilibrium shift is attributable to the additional steric contacts in the open-conductive structure, which are evoked by the increased side-chain bulkiness of the residues lining the transmembrane helix. Our results suggest that the alteration in the conformational equilibrium of the intracellular K+-gate is one of the fundamental mechanisms underlying the dysfunctions of K+ channels caused by disease-related mutations.


Asunto(s)
Proteínas Bacterianas/metabolismo , Activación del Canal Iónico/genética , Canales de Potasio/metabolismo , Potasio/metabolismo , Alanina/genética , Ataxia/genética , Proteínas Bacterianas/genética , Proteínas Bacterianas/aislamiento & purificación , Epilepsia/genética , Humanos , Síndrome de QT Prolongado/genética , Espectroscopía de Resonancia Magnética , Simulación de Dinámica Molecular , Mutación Missense , Canales de Potasio/genética , Canales de Potasio/aislamiento & purificación , Conformación Proteica en Hélice alfa/genética , Proteínas Recombinantes/genética , Proteínas Recombinantes/aislamiento & purificación , Proteínas Recombinantes/metabolismo , Streptomyces lividans , Valina/genética
16.
Sci Rep ; 10(1): 8132, 2020 05 18.
Artículo en Inglés | MEDLINE | ID: mdl-32424180

RESUMEN

Some neural network can be trained by transfer learning, which uses a pre-trained neural network as the source task, for a small target task's dataset. The performance of the transfer learning depends on the knowledge (i.e., layers) selected from the pre-trained network. At present, this knowledge is usually chosen by humans. The transfer learning method PathNet automatically selects pre-trained modules or adjustable modules in a modular neural network. However, PathNet requires modular neural networks as the pre-trained networks, therefore non-modular pre-trained neural networks are currently unavailable. Consequently, PathNet limits the versatility of the network structure. To address this limitation, we propose Stepwise PathNet, which regards the layers of a non-modular pre-trained neural network as the module in PathNet and selects the layers automatically through training. In an experimental validation of transfer learning from InceptionV3 pre-trained on the ImageNet dataset to networks trained on three other datasets (CIFAR-100, SVHN and Food-101), Stepwise PathNet was up to 8% and 10% more accurate than finely tuned and from-scratch approaches, respectively. Also, some of the selected layers were not supported by the layer functions assumed in PathNet.

17.
Sci Adv ; 6(12): eaay8544, 2020 03.
Artículo en Inglés | MEDLINE | ID: mdl-32206717

RESUMEN

The lipid composition of the plasma membrane is a key parameter in controlling signal transduction through G protein-coupled receptors (GPCRs). Adenosine A2A receptor (A2AAR) is located in the lipid bilayers of cells, containing acyl chains derived from docosahexaenoic acid (DHA). For the NMR studies, we prepared A2AAR in lipid bilayers of nanodiscs, containing DHA chains and other acyl chains. The DHA chains in nanodiscs enhanced the activation of G proteins by A2AAR. Our NMR studies revealed that the DHA chains redistribute the multiple conformations of A2AAR toward those preferable for G protein binding. In these conformations, the rotational angle of transmembrane helix 6 is similar to that in the A2AAR-G protein complex, suggesting that the population shift of the equilibrium causes the enhanced activation of G protein by A2AAR. These findings provide insights into the control of neurotransmissions by A2AAR and the effects of lipids on various GPCR functions.


Asunto(s)
Agonistas del Receptor de Adenosina A2/química , Agonistas del Receptor de Adenosina A2/farmacología , Ácidos Docosahexaenoicos/química , Ácidos Docosahexaenoicos/farmacología , Espectroscopía de Resonancia Magnética , Receptor de Adenosina A2A/química , Receptor de Adenosina A2A/metabolismo , Membrana Celular/metabolismo , Ácidos Docosahexaenoicos/análogos & derivados , Membrana Dobles de Lípidos , Modelos Moleculares , Conformación Molecular , Unión Proteica , Proteínas Recombinantes , Transducción de Señal , Solventes , Relación Estructura-Actividad
18.
Nat Chem Biol ; 16(4): 430-439, 2020 04.
Artículo en Inglés | MEDLINE | ID: mdl-31959965

RESUMEN

G-protein-coupled receptors (GPCRs) are seven-transmembrane proteins mediating cellular signals in response to extracellular stimuli. Although three-dimensional structures showcase snapshots that can be sampled in the process and nuclear magnetic resonance detects conformational equilibria, the mechanism by which agonist-activated GPCRs interact with various effectors remains elusive. Here, we used paramagnetic nuclear magnetic resonance for leucine amide resonances to visualize the structure of ß2-adrenoreceptor in the full agonist-bound state, without thermostabilizing mutations abolishing its activity. The structure exhibited a unique orientation of the intracellular half of the transmembrane helix 6, forming a cluster of G-protein-interacting residues. Furthermore, analyses of efficacy-dependent chemical shifts of the residues near the pivotal PIF microswitch identified an equilibrium among three conformations, including one responsible for the varied signal level in each ligand-bound state. Together, these results provide a structural basis for the dynamic activation of GPCRs and shed light on GPCR-mediated signal transduction.


Asunto(s)
Receptores Adrenérgicos beta 2/metabolismo , Receptores Adrenérgicos beta 2/ultraestructura , Cristalografía por Rayos X/métodos , Humanos , Ligandos , Espectroscopía de Resonancia Magnética/métodos , Proteínas de la Membrana/metabolismo , Modelos Moleculares , Unión Proteica/fisiología , Conformación Proteica , Receptores Acoplados a Proteínas G/metabolismo , Transducción de Señal/fisiología
19.
Acta Diabetol ; 57(2): 173-182, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31375898

RESUMEN

AIMS: Practical management guidelines for impaired glucose tolerance (IGT) have not been established. Although IGT is a potent marker of cardiovascular disease (CVD), it is still controversial whether its magnitude of CVD risk is comparable to that of frank diabetes. Moreover, information on long-term clinical outcomes of IGT patients undergoing coronary revascularization is limited. The aim of the present work was to investigate the 10-year prognostic impact of IGT in comparison with diabetes in patients with CAD undergoing coronary revascularization. METHODS: This cohort recruited from two Japanese clinical sites included patients with coronary artery disease (CAD) undergoing percutaneous coronary intervention (PCI) between 2004 and 2008. Patients were categorized into previously known diabetes (PKD, n = 197), newly diagnosed diabetes (NDD, n = 51), and IGT (n = 50) groups according to oral glucose tolerance test results except for PKD. The primary end point was defined as a composite of cardiovascular death, myocardial infarction, stroke, repeat revascularization, and heart failure hospitalization. RESULTS: The cumulative risk of the primary outcome was significantly higher in the PKD and IGT than in the NDD (log-rank test p = 0.017). A Cox proportional hazards model demonstrated that IGT (hazard ratio [HR], 7.91; 95% confidence interval [CI], 1.84-27.58) and creatinine clearance (HR, 7.89, 95% CI, 2.73-19.10) were predictors of long-term CVD risk, while NDD and PKD were not. CONCLUSIONS: IGT significantly increased the long-term risk of developing CVD in patients with CAD after PCI compared with diabetes.


Asunto(s)
Enfermedades Cardiovasculares/etiología , Complicaciones de la Diabetes/etiología , Diabetes Mellitus/metabolismo , Intolerancia a la Glucosa , Anciano , Enfermedades Cardiovasculares/metabolismo , Complicaciones de la Diabetes/metabolismo , Femenino , Estudios de Seguimiento , Prueba de Tolerancia a la Glucosa , Humanos , Masculino , Persona de Mediana Edad , Pronóstico , Estudios Prospectivos , Factores de Riesgo
20.
Int J Cardiovasc Imaging ; 36(2): 337-346, 2020 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-31628575

RESUMEN

Fractional flow reserve (FFR) is an established method for diagnosing physiological coronary artery stenosis. A method for computing FFR using coronary computed tomography (CT) images was recently developed. However, its calculation requires off-site supercomputer analysis. Here, we report the preliminary result of a method using simple estimation of boundary conditions. The lumen boundaries of the coronary arteries were semi-automatically delineated using full width at half maximum of CT number profiles. The computational fluid dynamics (CFD) of the blood flow was performed using the boundary conditions of a fixed pressure at the coronary ostium and flow rates at each outlet. The total inflow at the coronary ostium was estimated based on the uniform wall shear stress hypothesis and corrected using a hyperemic multiplier to gain a hyperemic flow rate. The flow distribution from a parent vessel to the downstream daughter vessels was determined according to Murray's law. FFR estimated by CFD was calculated as FFRCFD = Pd/Pa. We collected patients who underwent coronary CT and coronary angiography followed by invasively measured FFR and compared FFRCFD with FFR. Sensitivity, specificity, and correlations were assessed. A total of 48 patients and 72 arteries were assessed. The correlation coefficient of FFRCFD with FFR was 0.56. The cut-off value was ≤ 0.80, sensitivity was 59.1%, and specificity was 94.0%. CFD-based FFR using simple boundary conditions for on-site clinical computation provided FFRCFD values that were moderately correlated with invasively measured FFR.


Asunto(s)
Angiografía por Tomografía Computarizada , Angiografía Coronaria/métodos , Enfermedad de la Arteria Coronaria/diagnóstico por imagen , Vasos Coronarios/diagnóstico por imagen , Reserva del Flujo Fraccional Miocárdico , Modelos Cardiovasculares , Modelación Específica para el Paciente , Anciano , Enfermedad de la Arteria Coronaria/fisiopatología , Vasos Coronarios/fisiopatología , Femenino , Humanos , Hidrodinámica , Masculino , Persona de Mediana Edad , Valor Predictivo de las Pruebas , Reproducibilidad de los Resultados , Estudios Retrospectivos
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