36 research outputs found

    Extracellular Kir2.1C122Y Mutant Upsets Kir2.1-PIP2 Bonds and Is Arrhythmogenic in Andersen-Tawil Syndrome.

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    BACKGROUND Andersen-Tawil syndrome type 1 is a rare heritable disease caused by mutations in the gene coding the strong inwardly rectifying K+ channel Kir2.1. The extracellular Cys (cysteine)122-to-Cys154 disulfide bond in the channel structure is crucial for proper folding but has not been associated with correct channel function at the membrane. We evaluated whether a human mutation at the Cys122-to-Cys154 disulfide bridge leads to Kir2.1 channel dysfunction and arrhythmias by reorganizing the overall Kir2.1 channel structure and destabilizing its open state. METHODS We identified a Kir2.1 loss-of-function mutation (c.366 A>T; p.Cys122Tyr) in an ATS1 family. To investigate its pathophysiological implications, we generated an AAV9-mediated cardiac-specific mouse model expressing the Kir2.1C122Y variant. We employed a multidisciplinary approach, integrating patch clamping and intracardiac stimulation, molecular biology techniques, molecular dynamics, and bioluminescence resonance energy transfer experiments. RESULTS Kir2.1C122Y mice recapitulated the ECG features of ATS1 independently of sex, including corrected QT prolongation, conduction defects, and increased arrhythmia susceptibility. Isolated Kir2.1C122Y cardiomyocytes showed significantly reduced inwardly rectifier K+ (IK1) and inward Na+ (INa) current densities independently of normal trafficking. Molecular dynamics predicted that the C122Y mutation provoked a conformational change over the 2000-ns simulation, characterized by a greater loss of hydrogen bonds between Kir2.1 and phosphatidylinositol 4,5-bisphosphate than wild type (WT). Therefore, the phosphatidylinositol 4,5-bisphosphate-binding pocket was destabilized, resulting in a lower conductance state compared with WT. Accordingly, on inside-out patch clamping, the C122Y mutation significantly blunted Kir2.1 sensitivity to increasing phosphatidylinositol 4,5-bisphosphate concentrations. In addition, the Kir2.1C122Y mutation resulted in channelosome degradation, demonstrating temporal instability of both Kir2.1 and NaV1.5 proteins. CONCLUSIONS The extracellular Cys122-to-Cys154 disulfide bond in the tridimensional Kir2.1 channel structure is essential for the channel function. We demonstrate that breaking disulfide bonds in the extracellular domain disrupts phosphatidylinositol 4,5-bisphosphate-dependent regulation, leading to channel dysfunction and defects in Kir2.1 energetic stability. The mutation also alters functional expression of the NaV1.5 channel and ultimately leads to conduction disturbances and life-threatening arrhythmia characteristic of Andersen-Tawil syndrome type 1.The authors thank the Centro Nacional de Investigaciones Cardiovasculares (CNIC) Viral Vectors Unit for producing the adeno-associated virus serotype 9. Confocal experiments were conducted at the CNIC Microscopy and Dynamic Imaging Unit. The authors thank the CNIC Bioinformatics Unit for generating the in silico homology modeling simulations, F-function analysis, and helpful discussions. The authors also thank the Centro de Supercomputación de Galicia for the use of the Finis Terrae III supercomputer to perform molecular dynamics studies. The CNIC was supported by the Instituto de Salud Carlos III, the Ministerio de Ciencia, Innovación y Universidades, and the Pro CNIC Foundation and is a Severo Ochoa Center of Excellence (grant CEX2020-001041-S funded by MICIU/AEI/10.13039/501100011033). This work was supported by the National heart, Lung and Blood Institute under National Institutes of Health (NIH) grant R01HL163943; the La Caixa Banking Foundation project code HR18-00304 (grant LCF/PR/HR19/52160013); grants PI-FIS-2020, PI20/01220, PI-FIS-2023, and PI23/01039 from the Instituto de Salud Carlos III and cofunded by the Fondo Europeo de Desarrollo Regional (FEDER) and the European Union, respectively; grants PID2020-116935RB-I00 and BFU2016-75144-R funded by MICIU/AEI/10.13039/501100011033; the Fundación La Marató de TV3 (736/C/2020) amb el suport de la Fundació La Marató de TV3; the CIBER (Centro de Investigación Biomédica en Red) de Enfermedades Cardiovasculares (grant CB16/11/00458); the European Union’s Horizon 2020 grant agreement GA-965286; and the Program S2022/BMD7229-CM ARCADIACM funded by the Comunidad de Madrid to J. Jalife; grant PID2021-126423OB-C22 (to M. Martín-Martínez) funded by MICIU/AEI/10.13039/501100011033; and European Regional Development Fund (ERDF) grant PID2022-137214OB-C22 (to M. Gutierrez-Rodríguez) funded by MICIU/AEI/10.13039/501100011033. The imaging studies were performed in the TRIMA@CNIC (Infraestructura de Imagen Traslacional Avanzada del CNIC) node of the ICTS ReDIB (Infraestructuras Científicas y Técnicas Singulares: Red Distribuida de Imagen Biomédica) grant ICTS-2018- 04-CNIC-16 funded by MICIU/AEI/10.13039/501100011033 and ERDF, and project EQC2018-005070-P funded by MICIU/AEI/10.13039/501100011033 and FEDER. A.I. Moreno-Manuel holds an formación profesional universitaria (FPU) contract (FPU20/01569) from the Ministerio de Universidades. J.M. Ruiz Robles holds an FPU contract (FPU22/03253) from the Ministerio de Universidades. L.K. Gutiérrez holds an FPI contract (PRE2018-083530) from the Ministerio de Economía y Competitividad de España cofunded by the Fondo Social Europeo, attached to project SEV-2015-0505-18-2. I. Martínez-Carrascoso holds a PFIS (Contratos predoctorales de formación en investigación en salud) contract (FI21/00243) funded by Instituto de Salud Carlos III and the Fondo Social Europeo Plus cofunded by the European Union. M.L. Vera-Pedrosa held contract PEJD-2019-PRE/BMD15982 funded by the Consejería de Educación e Investigación de la Comunidad de Madrid y Fondo Social Europeo.S

    Differential clinical characteristics and prognosis of intraventricular conduction defects in patients with chronic heart failure

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    Intraventricular conduction defects (IVCDs) can impair prognosis of heart failure (HF), but their specific impact is not well established. This study aimed to analyse the clinical profile and outcomes of HF patients with LBBB, right bundle branch block (RBBB), left anterior fascicular block (LAFB), and no IVCDs. Clinical variables and outcomes after a median follow-up of 21 months were analysed in 1762 patients with chronic HF and LBBB (n = 532), RBBB (n = 134), LAFB (n = 154), and no IVCDs (n = 942). LBBB was associated with more marked LV dilation, depressed LVEF, and mitral valve regurgitation. Patients with RBBB presented overt signs of congestive HF and depressed right ventricular motion. The LAFB group presented intermediate clinical characteristics, and patients with no IVCDs were more often women with less enlarged left ventricles and less depressed LVEF. Death occurred in 332 patients (interannual mortality = 10.8%): cardiovascular in 257, extravascular in 61, and of unknown origin in 14 patients. Cardiac death occurred in 230 (pump failure in 171 and sudden death in 59). An adjusted Cox model showed higher risk of cardiac death and pump failure death in the LBBB and RBBB than in the LAFB and the no IVCD groups. LBBB and RBBB are associated with different clinical profiles and both are independent predictors of increased risk of cardiac death in patients with HF. A more favourable prognosis was observed in patients with LAFB and in those free of IVCDs. Further research in HF patients with RBBB is warranted

    Multiancestry analysis of the HLA locus in Alzheimer’s and Parkinson’s diseases uncovers a shared adaptive immune response mediated by HLA-DRB1*04 subtypes

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    Across multiancestry groups, we analyzed Human Leukocyte Antigen (HLA) associations in over 176,000 individuals with Parkinson’s disease (PD) and Alzheimer’s disease (AD) versus controls. We demonstrate that the two diseases share the same protective association at the HLA locus. HLA-specific fine-mapping showed that hierarchical protective effects of HLA-DRB1*04 subtypes best accounted for the association, strongest with HLA-DRB1*04:04 and HLA-DRB1*04:07, and intermediary with HLA-DRB1*04:01 and HLA-DRB1*04:03. The same signal was associated with decreased neurofibrillary tangles in postmortem brains and was associated with reduced tau levels in cerebrospinal fluid and to a lower extent with increased Aβ42. Protective HLA-DRB1*04 subtypes strongly bound the aggregation-prone tau PHF6 sequence, however only when acetylated at a lysine (K311), a common posttranslational modification central to tau aggregation. An HLA-DRB1*04-mediated adaptive immune response decreases PD and AD risks, potentially by acting against tau, offering the possibility of therapeutic avenues

    What’s New in the Treatment of Enterococcal Endocarditis?

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    Enterococcus spp. are among the common pathogens causing infective endocarditis (IE). Despite major medical advances and new potent antimicrobial agents, the mortality has not significantly improved for several decades. The usual lack of bactericidal activity of penicillin or ampicillin, the toxicity from the combination of penicillin plus aminoglycosides, and the increased reports of high-level resistance to aminoglycosides have led to the exploration of other regimens for treatment of Enterococcus faecalis IE. As an example, ampicillin plus ceftriaxone is now a well-recognized regimen for this organism. However, the emerging of new drug resistances in Enterococcus faecium dramatically reduces the therapeutic alternatives for this organism in IE which continues to be an immense challenge for clinicians even with the availability of newer antimicrobial agents. This article summarizes the current treatment options for enterococcal endocarditis and reviews of recent publications on the topic

    X-linked recessive TLR7 deficiency in ~1% of men under 60 years old with life-threatening COVID-19

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    Publisher Copyright: Copyright © 2021Autosomal inborn errors of type I IFN immunity and autoantibodies against these cytokines underlie at least 10% of critical COVID-19 pneumonia cases. We report very rare, biochemically deleterious X-linked TLR7 variants in 16 unrelated male individuals aged 7 to 71 years (mean, 36.7 years) from a cohort of 1202 male patients aged 0.5 to 99 years (mean, 52.9 years) with unexplained critical COVID-19 pneumonia. None of the 331 asymptomatically or mildly infected male individuals aged 1.3 to 102 years (mean, 38.7 years) tested carry such TLR7 variants (P = 3.5 × 10−5). The phenotypes of five hemizygous relatives of index cases infected with SARS-CoV-2 include asymptomatic or mild infection (n = 2) or moderate (n = 1), severe (n = 1), or critical (n = 1) pneumonia. Two patients from a cohort of 262 male patients with severe COVID-19 pneumonia (mean, 51.0 years) are hemizygous for a deleterious TLR7 variant. The cumulative allele frequency for deleterious TLR7 variants in the male general population is <6.5 × 10−4. We show that blood B cell lines and myeloid cell subsets from the patients do not respond to TLR7 stimulation, a phenotype rescued by wild-type TLR7. The patients’ blood plasmacytoid dendritic cells (pDCs) produce low levels of type I IFNs in response to SARS-CoV-2. Overall, X-linked recessive TLR7 deficiency is a highly penetrant genetic etiology of critical COVID-19 pneumonia, in about 1.8% of male patients below the age of 60 years. Human TLR7 and pDCs are essential for protective type I IFN immunity against SARS-CoV-2 in the respiratory tract.Peer reviewe

    Differential clinical characteristics and prognosis of intraventricular conduction defects in patients with chronic heart failure

    No full text
    Intraventricular conduction defects (IVCDs) can impair prognosis of heart failure (HF), but their specific impact is not well established. This study aimed to analyse the clinical profile and outcomes of HF patients with LBBB, right bundle branch block (RBBB), left anterior fascicular block (LAFB), and no IVCDs. Clinical variables and outcomes after a median follow-up of 21 months were analysed in 1762 patients with chronic HF and LBBB (n = 532), RBBB (n = 134), LAFB (n = 154), and no IVCDs (n = 942). LBBB was associated with more marked LV dilation, depressed LVEF, and mitral valve regurgitation. Patients with RBBB presented overt signs of congestive HF and depressed right ventricular motion. The LAFB group presented intermediate clinical characteristics, and patients with no IVCDs were more often women with less enlarged left ventricles and less depressed LVEF. Death occurred in 332 patients (interannual mortality = 10.8%): cardiovascular in 257, extravascular in 61, and of unknown origin in 14 patients. Cardiac death occurred in 230 (pump failure in 171 and sudden death in 59). An adjusted Cox model showed higher risk of cardiac death and pump failure death in the LBBB and RBBB than in the LAFB and the no IVCD groups. LBBB and RBBB are associated with different clinical profiles and both are independent predictors of increased risk of cardiac death in patients with HF. A more favourable prognosis was observed in patients with LAFB and in those free of IVCDs. Further research in HF patients with RBBB is warranted
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