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| 2. |
- Pantazis, A., et al.
(författare)
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Tracking the motion of the KV1.2 voltage sensor reveals the molecular perturbations caused by a de novo mutation in a case of epilepsy
- 2020
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Ingår i: Journal of Physiology. - : Blackwell Publishing Ltd. - 0022-3751 .- 1469-7793.
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Tidskriftsartikel (refereegranskat)abstract
- Key points: KV1.2 channels, encoded by the KCNA2 gene, regulate neuronal excitability by conducting K+ upon depolarization. A new KCNA2 missense variant was discovered in a patient with epilepsy, causing amino acid substitution F302L at helix S4, in the KV1.2 voltage-sensing domain. Immunocytochemistry and flow cytometry showed that F302L does not impair KCNA2 subunit surface trafficking. Molecular dynamics simulations indicated that F302L alters the exposure of S4 residues to membrane lipids. Voltage clamp fluorometry revealed that the voltage-sensing domain of KV1.2-F302L channels is more sensitive to depolarization. Accordingly, KV1.2-F302L channels opened faster and at more negative potentials; however, they also exhibited enhanced inactivation: that is, F302L causes both gain- and loss-of-function effects. Coexpression of KCNA2-WT and -F302L did not fully rescue these effects. The proband's symptoms are more characteristic of patients with loss of KCNA2 function. Enhanced KV1.2 inactivation could lead to increased synaptic release in excitatory neurons, steering neuronal circuits towards epilepsy. Abstract: An exome-based diagnostic panel in an infant with epilepsy revealed a previously unreported de novo missense variant in KCNA2, which encodes voltage-gated K+ channel KV1.2. This variant causes substitution F302L, in helix S4 of the KV1.2 voltage-sensing domain (VSD). F302L does not affect KCNA2 subunit membrane trafficking. However, it does alter channel functional properties, accelerating channel opening at more hyperpolarized membrane potentials, indicating gain of function. F302L also caused loss of KV1.2 function via accelerated inactivation onset, decelerated recovery and shifted inactivation voltage dependence to more negative potentials. These effects, which are not fully rescued by coexpression of wild-type and mutant KCNA2 subunits, probably result from the enhancement of VSD function, as demonstrated by optically tracking VSD depolarization-evoked conformational rearrangements. In turn, molecular dynamics simulations suggest altered VSD exposure to membrane lipids. Compared to other encephalopathy patients with KCNA2 mutations, the proband exhibits mild neurological impairment, more characteristic of patients with KCNA2 loss of function. Based on this information, we propose a mechanism of epileptogenesis based on enhanced KV1.2 inactivation leading to increased synaptic release preferentially in excitatory neurons, and hence the perturbation of the excitatory/inhibitory balance of neuronal circuits.
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- Neiburga, KD, et al.
(författare)
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Vascular Tissue Specific miRNA Profiles Reveal Novel Correlations with Risk Factors in Coronary Artery Disease
- 2021
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Ingår i: Biomolecules. - : MDPI AG. - 2218-273X. ; 11:11
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Tidskriftsartikel (refereegranskat)abstract
- Cardiovascular disease (CVD) is the leading cause of morbidity and mortality worldwide. Non-coding RNAs have already been linked to CVD development and progression. While microRNAs (miRs) have been well studied in blood samples, there is little data on tissue-specific miRs in cardiovascular relevant tissues and their relation to cardiovascular risk factors. Tissue-specific miRs derived from Arteria mammaria interna (IMA) from 192 coronary artery disease (CAD) patients undergoing coronary artery bypass grafting (CABG) were analyzed. The aims of the study were 1) to establish a reference atlas which can be utilized for identification of novel diagnostic biomarkers and potential therapeutic targets, and 2) to relate these miRs to cardiovascular risk factors. Overall, 393 individual miRs showed sufficient expression levels and passed quality control for further analysis. We identified 17 miRs–miR-10b-3p, miR-10-5p, miR-17-3p, miR-21-5p, miR-151a-5p, miR-181a-5p, miR-185-5p, miR-194-5p, miR-199a-3p, miR-199b-3p, miR-212-3p, miR-363-3p, miR-548d-5p, miR-744-5p, miR-3117-3p, miR-5683 and miR-5701–significantly correlated with cardiovascular risk factors (correlation coefficient >0.2 in both directions, p-value (p < 0.006, false discovery rate (FDR) <0.05). Of particular interest, miR-5701 was positively correlated with hypertension, hypercholesterolemia, and diabetes. In addition, we found that miR-629-5p and miR-98-5p were significantly correlated with acute myocardial infarction. We provide a first atlas of miR profiles in IMA samples from CAD patients. In perspective, these miRs might play an important role in improved risk assessment, mechanistic disease understanding and local therapy of CAD.
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| 4. |
- Axelsson, Anton, 1991, et al.
(författare)
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Asymmetric Synthesis of Dihydropyranones with Three Contiguous Stereocenters by an NHC-Catalyzed Kinetic Resolution
- 2021
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Ingår i: European Journal of Organic Chemistry. - : Wiley. - 1434-193X .- 1099-0690. ; 2021:25, s. 3657-3661
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Tidskriftsartikel (refereegranskat)abstract
- An oxidative NHC-catalyzed kinetic resolution (KR) of racemic mixtures is presented. The developed reaction furnishes tricyclic dihydropyranones with three contiguous stereocenters in excellent dia- and enantioselectivity, with good-to-moderate yields. Mechanistic studies indicate that the rate-determining step of the reaction is the formation of the Breslow intermediate, while the selectivity determining step occurs later in the mechanism. The presented methodology enables rapid synthesis of complex structures in a single step.
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| 6. |
- Enerbäck, Hanna, et al.
(författare)
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Validation of caries risk assessment methods in orthodontic patients
- 2020
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Ingår i: American Journal of Orthodontics and Dentofacial Orthopedics. - : Elsevier BV. - 0889-5406. ; 158, s. 92-101.e3
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Dental caries is an undesirable side effect of orthodontic treatment with fixed appliances. Caries lesions can result in long-term esthetic disturbance, costly interventions, and even interrupted treatment. Therefore, it is crucial to assess accurately both a patient's caries risk before treatment and their suitability for orthodontic treatment. This study aimed to evaluate the validity of 5 caries risk assessment methods for predicting caries outcome during orthodontic treatment: Cariogram, Caries Management by Risk Assessment (CAMBRA), R2, decayed filled teeth (DFT), and decayed initial filled surfaces (DiFS). Methods: A prospective longitudinal clinical study of 270 adolescents who were referred to the Specialist Clinic for Orthodontics, Mölndal Hospital, Sweden for treatment with fixed orthodontic appliances. The following data were collected before treatment: plaque index, radiographs to determine caries prevalence (DFT, DiFS), photographs to determine white-spot lesions, saliva samples (Streptococcus mutans and Lactobacilli), and responses to a questionnaire (regarding diet and oral hygiene). The variables were compiled to assess caries risk according to Cariogram, CAMBRA, and R2. Radiographs were also taken posttreatment to assess caries incidence. The caries outcomes after treatment were analyzed and compared with the caries risk, assessed by the caries risk assessment methods at baseline. Results: DiFS proved to be the most reliable method for predicting caries during orthodontic treatment, presenting the highest area under the receiver operating characteristic curve for both manifest caries (0.77) and initial caries (0.71). Conclusions: The DiFS prevalence index was demonstrated to be useful in identifying patients who are at risk for developing manifest and initial caries during orthodontic treatment. © 2020
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| 7. |
- Ferreira, Catarina, et al.
(författare)
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Polyphasic characterization of carbapenemresistant Klebsiella pneumoniae clinical isolates suggests vertical transmission of the bla KPC-3 gene
- 2021
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203 .- 1932-6203. ; 16:2 Febuary
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Tidskriftsartikel (refereegranskat)abstract
- Carbapenem-resistant Klebsiella pneumoniae are a major global threat in healthcare facilities. The propagation of carbapenem resistance determinants can occur through vertical transmission, with genetic elements being transmitted by the host bacterium, or by horizontal transmission, with the same genetic elements being transferred among distinct bacterial hosts. This work aimed to track carbapenem resistance transmission by K. pneumoniae in a healthcare facility. The study involved a polyphasic approach based on conjugation assays, resistance phenotype and genotype analyses, whole genome sequencing, and plasmid characterization by pulsed field gel electrophoresis and optical DNA mapping. Out of 40 K. pneumoniae clinical isolates recovered over two years, five were carbapenem- and multidrug- resistant and belonged to multilocus sequence type ST147. These isolates harboured the carbapenemase encoding blaKPC-3 gene, integrated in conjugative plasmids of 140 kbp or 55 kbp, belonging to replicon types incFIA/incFIIK or incN/incFIIK, respectively. The two distinct plasmids encoding the blaKPC-3 gene were associated with distinct genetic lineages, as confirmed by optical DNA mapping and whole genome sequence analyses. These results suggested vertical (bacterial strain-based) transmission of the carbapenem-resistance genetic elements. Determination of the mode of transmission of antibiotic resistance in healthcare facilities, only possible based on polyphasic approaches as described here, is essential to control resistance propagation.
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| 8. |
- Fleetwood, Oliver, et al.
(författare)
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Molecular Insights from Conformational Ensembles via Machine Learning
- 2020
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Ingår i: Biophysical Journal. - : Biophysical Society. - 0006-3495 .- 1542-0086. ; 118:3, s. 765-780
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Tidskriftsartikel (refereegranskat)abstract
- Biomolecular simulations are intrinsically high dimensional and generate noisy data sets of ever-increasing size. Extracting important features from the data is crucial for understanding the biophysical properties of molecular processes, but remains a big challenge. Machine learning (ML) provides powerful dimensionality reduction tools. However, such methods are often criticized as resembling black boxes with limited human-interpretable insight. We use methods from supervised and unsupervised ML to efficiently create interpretable maps of important features from molecular simulations. We benchmark the performance of several methods, including neural networks, random forests, and principal component analysis, using a toy model with properties reminiscent of macromolecular behavior. We then analyze three diverse biological processes: conformational changes within the soluble protein calmodulin, ligand binding to a G protein-coupled receptor, and activation of an ion channel voltage-sensor domain, unraveling features critical for signal transduction, ligand binding, and voltage sensing. This work demonstrates the usefulness of ML in understanding biomolecular states and demystifying complex simulations.
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| 9. |
- Kang, Po Wei, et al.
(författare)
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Calmodulin acts as a state-dependent switch to control a cardiac potassium channel opening
- 2020
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Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 6:50
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Tidskriftsartikel (refereegranskat)abstract
- Calmodulin (CaM) and phosphatidylinositol 4,5-bisphosphate (PIP2) are potent regulators of the voltage-gated potassium channel KCNQ1 (K(v)7.1), which conducts the cardiac I-Ks current. Although cryo-electron microscopy structures revealed intricate interactions between the KCNQ1 voltage-sensing domain (VSD), CaM, and PIP2, the functional consequences of these interactions remain unknown. Here, we show that CaM-VSD interactions act as a state-dependent switch to control KCNQ1 pore opening. Combined electrophysiology and molecular dynamics network analysis suggest that VSD transition into the fully activated state allows PIP 2 to compete with CaM for binding to VSD. This leads to conformational changes that alter VSD-pore coupling to stabilize open states. We identify a motif in the KCNQ1 cytosolic domain, which works downstream of CaM-VSD interactions to facilitate the conformational change. Our findings suggest a gating mechanism that integrates PIP2 and CaM in KCNQ1 voltage-dependent activation, yielding insights into how KCNQ1 gains the phenotypes critical for its physiological function.
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