Correction of Ito in human induced pluripotent stem Cell-derived cardiomyocyte carrying DPP6 mutation in early repolarization syndrome by CRISPR/Cas9 genome editing.

Early repolarization syndrome (ERS) is defined as occurring in patients with early repolarization pattern who have survived idiopathic ventricular fibrillation with clinical evaluation unrevealing for other explanations. The pathophysiologic basis of the ERS is currently uncertain. The objective of the present study was to examine the electrophysiological mechanism of ERS utilizing induced pluripotent stem cells (iPSCs) and CRISPR/Cas9 genome editing. Whole genome sequencing was used to identify the DPP6 (c.2561T > C/p.L854P) variant in four families with sudden cardiac arrest induced by ERS. Cardiomyocytes were generated from iPSCs from a 14-year-old boy in the four families with ERS and an unrelated healthy control subject. Patch clamp recordings revealed more significant prolongation of the action potential duration (APD) and increased transient outward potassium current (Ito) (103.97 ± 18.73 pA/pF vs 44.36 ± 16.54 pA/pF at +70 mV, P < 0.05) in ERS cardiomyocytes compared with control cardiomyocytes. Of note, the selective correction of the causal variant in iPSC-derived cardiomyocytes using CRISPR/Cas9 gene editing normalized the Ito, whereas prolongation of the APD remained unchanged. ERS cardiomyocytes carrying DPP6 mutation increased Ito and lengthen APD, which maybe lay the electrophysiological foundation of ERS.

Serum electrolyte concentrations and risk of atrial fibrillation: an observational and mendelian randomization study.

BACKGROUND: Atrial fibrillation (AF) is a prevalent arrhythmic condition resulting in increased stroke risk and is associated with high mortality. Electrolyte imbalance can increase the risk of AF, where the relationship between AF and serum electrolytes remains unclear. METHODS: A total of 15,792 individuals were included in the observational study, with incident AF ascertainment in the Atherosclerosis Risk in Communities (ARIC) study. The Cox regression models were applied to calculate the hazard ratio (HR) and 95% confidence interval (CI) for AF based on different serum electrolyte levels. Mendelian randomization (MR) analyses were performed to examine the causal association. RESULTS: In observational study, after a median 19.7 years of follow-up, a total of 2551 developed AF. After full adjustment, participants with serum potassium below the 5th percentile had a higher risk of AF relative to participants in the middle quintile. Serum magnesium was also inversely associated with the risk of AF. An increased incidence of AF was identified in individuals with higher serum phosphate percentiles. Serum calcium levels were not related to AF risk. Moreover, MR analysis indicated that genetically predicted serum electrolyte levels were not causally associated with AF risk. The odds ratio for AF were 0.999 for potassium, 1.044 for magnesium, 0.728 for phosphate, and 0.979 for calcium, respectively. CONCLUSIONS: Serum electrolyte disorders such as hypokalemia, hypomagnesemia and hyperphosphatemia were associated with an increased risk of AF and may also serve to be prognostic factors. However, the present study did not support serum electrolytes as causal mediators for AF development.

High-Temperature Anomalous Metal States in Iron-Based Interface Superconductors.

The nature of the anomalous metal state has been a major puzzle in condensed matter physics for more than three decades. Here, we report systematic investigation and modulation of the anomalous metal states in high-temperature interface superconductor FeSe films on SrTiO_{3} substrate. Remarkably, under zero magnetic field, the anomalous metal state persists up to 20 K in pristine FeSe films, an exceptionally high temperature standing out from previous observations. In stark contrast, for the FeSe films with nanohole arrays, the characteristic temperature of the anomalous metal state is considerably reduced. We demonstrate that the observed anomalous metal states originate from the quantum tunneling of vortices adjusted by the Ohmic dissipation. Our work offers a perspective for understanding the origin and modulation of the anomalous metal states in two-dimensional bosonic systems.

Sorting Out the Latest Advances in Separators and Pilot-Scale Microbial Electrochemical Systems for Wastewater Treatment: Concomitant Development, Practical Application, and Future Perspective.

To date, dozens of pilot-scale microbial fuel cell (MFC) devices have been successfully developed worldwide for treating various types of wastewater. The availability and configurations of separators are determining factors for the economic feasibility, efficiency, sustainability, and operability of these devices. Thus, the concomitant advances between the separators and pilot-scale MFC configurations deserve further clarification. The analysis of separator configurations has shown that their evolution proceeds as follows: from ion-selective to ion-non-selective, from nonpermeable to permeable, and from abiotic to biotic. Meanwhile, their cost is decreasing and their availability is increasing. Notably, the novel MFCs configured with biotic separators are superior to those configured with abiotic separators in terms of wastewater treatment efficiency and capital cost. Herein, a highly comprehensive review of pilot-scale MFCs (>100 L) has been conducted, and we conclude that the intensive stack of the liquid cathode configuration is more advantageous when wastewater treatment is the highest priority. The use of permeable biotic separators ensures hydrodynamic continuity within the MFCs and simplifies reactor configuration and operation. In addition, a systemic comparison is conducted between pilot-scale MFC devices and conventional decentralized wastewater treatment processes. MFCs showed comparable cost, higher efficiency, long-term stability, and significant superiority in carbon emission reduction. The development of separators has greatly contributed to the availability and usability of MFCs, which will play an important role in various wastewater treatment scenarios in the future.

The impact of anxiety on gait impairments in Parkinson's disease: insights from sensor-based gait analysis.

BACKGROUND: Sensor-based gait analysis provides a robust quantitative tool for assessing gait impairments and their associated factors in Parkinson's disease (PD). Anxiety is observed to interfere with gait clinically, but this has been poorly investigated. Our purpose is to utilize gait analysis to uncover the effect of anxiety on gait in patients with PD. METHODS: We enrolled 38 and 106 PD patients with and without anxiety, respectively. Gait parameters were quantitively examined and compared between two groups both in single-task (ST) and dual-task (DT) walking tests. Multiple linear regression was applied to evaluate whether anxiety independently contributed to gait impairments. RESULTS: During ST, PD patients with anxiety presented significantly shorter stride length, lower gait velocity, longer stride time and stance time, longer stance phase, smaller toe-off (TO) and heel-strike (HS) angles than those without anxiety. While under DT status, the differences were diminished. Multiple linear regression analysis demonstrated that anxiety was an independent factor to a serials of gait parameters, particularly ST-TO (B = -2.599, (-4.82, -0.38)), ST-HS (B = -2.532, (-4.71, -0.35)), ST-TO-CV (B = 4.627, (1.71, 7.64)), ST-HS-CV(B = 4.597, (1.66, 7.53)), ST stance phase (B = 1.4, (0.22, 2.58)), and DT stance phase (B = 1.749, (0.56, 2.94)). CONCLUSION: Our study discovered that anxiety has a significant impact on gait impairments in PD patients, especially exacerbating shuffling steps and prolonging stance phase. These findings highlight the importance of addressing anxiety in PD precision therapy to achieve better treatment outcomes.

Quantum phase transitions in two-dimensional superconductors: a review on recent experimental progress.

Superconductor-insulator/metal transition (SMT) as a paradigm of quantum phase transition has been a research highlight over the last three decades. Benefit from recent developments in the fabrication and measurements of two-dimensional (2D) superconducting films and nanodevices, unprecedented quantum phenomena have been revealed in the quantum phase transitions of 2D superconductors. In this review, we introduce the recent progress on quantum phase transitions in 2D superconductors, focusing on the quantum Griffiths singularity (QGS) and anomalous metal state. Characterized by a divergent critical exponent when approaching zero temperature, QGS of SMT is discovered in ultrathin crystalline Ga films and subsequently detected in various 2D superconductors. The universality of QGS indicates the profound influence of quenched disorder on quantum phase transitions. Besides, in a 2D superconducting system, whether a metallic ground state can exist is a long-sought mystery. Early experimental studies indicate an intermediate metallic state in the quantum phase transition of 2D superconductors. Recently, in high-temperature superconducting films with patterned nanopores, a robust anomalous metal state (i.e. quantum metal or Bose metal) has been detected, featured as the saturated resistance in the low temperature regime. Moreover, the charge-2equantum oscillations are observed in nanopatterned films, indicating the bosonic nature of the anomalous metal state and ending the debate on whether bosons can exist as a metal. The evidences of the anomalous metal states have also been reported in crystalline epitaxial thin films and exfoliated nanoflakes, as well as granular composite films. High quality filters are used in these works to exclude the influence of external high frequency noises in ultralow temperature measurements. The observations of QGS and metallic ground states in 2D superconductors not only reveal the prominent role of quantum fluctuations and dissipations but also provide new perspective to explore quantum phase transitions in superconducting systems.

Arabidopsis nucleoporin NUP96 mediates plant salt tolerance by modulating the transcription of salt-responsive genes.

MAIN CONCLUSION: Physiological and molecular tests show that NUP96 plays an important role in the plant response to salt stress, resulting from the reprogramming of transcriptomic profiles, which are likely to be mediated by the influence on the nuclear/cytosol shuttling of the key regulators of salt tolerance. As a key component of the nuclear pore complex (NPC), nucleoporin 96 (NUP96) is critical for modulating plant development and interactions with environmental factors, but whether NUP96 is involved in the salt response is still unknown. Here, we analyzed the role of Arabidopsis NUP96 under salt stress. The loss-of-function mutant nup96 exhibited salt sensitivity in terms of rosette growth and root elongation, and showed attenuated capacity in maintaining ion and ROS homeostasis, which could be compensated for by the overexpression of NUP96. RNA sequencing revealed that many salt-responsive genes were misregulated after NUP96 mutation, and especially NUP96 is required for the expression of a large portion of salt-induced genes. This is likely correlated with the activity in facilitating nuclear/cytosol transport of the underlying regulators in salt tolerance such as the transcription factor ATAP2, targeted by eight downregulated genes in nup96 under salt stress. Our results illustrate that NUP96 plays an important role in the salt response, probably by regulating the nucleocytoplasmic shuttling of key mRNAs or proteins associated with plant salt responsiveness.

Insight into the Pseudocapacitive Behavior of Electroactive Biofilms in Response to Dynamic-Controlled Electron Transfer and Metabolism Kinetics for Current Generation in Water Treatment.

Electroactive biofilms (EBs) engage in complex electron transfer and storage processes involving intracellular and extracellular mediators with temporary electron storage capabilities. Consequently, electroactive biofilms exhibit pseudocapacitive behaviors during substrate degradation processes. However, comprehensive systematic research in this area has been lacking. This study demonstrated that the pseudocapacitive property was an intrinsic characteristic of EBs. This property represents dynamic-controlled electron transfer and is critical in current generation, unlike noncapacitive responses. Nontransient charge and discharge experiments revealed a correlation between capacitive charge accumulation and current generation in EBs. Additionally, analysis of substrate degradation suggested that the maximum power density (Pmax) changed with the kinetic constants of COD degradation, with pseudocapacitances of EBs directly proportional to Pmax. The interaction networks of key latent variables were evaluated through partial least-squares path modeling analysis. The results indicated that cytochrome c was closely associated with the formation of pseudocapacitance in EBs. In conclusion, pseudocapacitance can be considered a valuable indicator for assessing the complex electron transfer behavior of EBs. Pseudocapacitive biofilms have the potential to efficiently regulate biological reactions and serve as a promising carbon-neutral and renewable strategy for energy generation and storage. An in-depth understanding of the intrinsic property of pseudocapacitive behavior in EBs can undoubtedly advance the development of this concept in the future.

Modification Method of High-Efficiency Organic Bentonite for Drilling Fluids: A Review.

The requirements for drilling bentonites are tightening due to ever-increasing demands for petroleum resources, coupled with cost and reaction technology constraints. In addition to raising the risk of drilling, bentonite's poor performance also raises the possibility of safety incidents and significant financial losses. Organically modified bentonites effectively reduce the consumption of drilling fluids, conserve resources, and lessen environmental effects. This paper aims to provide an overview of the several organic modification methods of bentonite for drilling fluids. It also evaluates the characteristics and application impacts of bentonite. We primarily describe the three popular modification methods represented by intercalation, coupling, and grafting. Also, this review provides the effect of molecular simulation on the investigation of structure in microconfined conditions. Through microlearning, organically modified bentonite with exceptional performance is to be further developed.

Ten-Eleven Translocation 1 Promotes Malignant Progression of Cholangiocarcinoma With Wild-Type Isocitrate Dehydrogenase 1.

BACKGROUND AND AIMS: Cholangiocarcinoma (CCA) is a highly lethal disease without effective therapeutic approaches. The whole-genome sequencing data indicate that about 20% of patients with CCA have isocitrate dehydrogenase 1 (IDH1) mutations, which have been suggested to target 2-oxoglutarate (OG)-dependent dioxygenases in promoting CCA carcinogenesis. However, the clinical study indicates that patients with CCA and mutant IDH1 have better prognosis than those with wild-type IDH1, further complicating the roles of 2-OG-dependent enzymes. APPROACH AND RESULTS: This study aimed to clarify if ten-eleven translocation 1 (TET1), which is one of the 2-OG-dependent enzymes functioning in regulating 5-hydroxymethylcytosine (5hmC) formation, is involved in CCA progression. By analyzing The Cancer Genome Atlas (TCGA) data set, TET1 mRNA was found to be substantially up-regulated in patients with CCA when compared with noncancerous bile ducts. Additionally, TET1 protein expression was significantly elevated in human CCA tumors. CCA cells were challenged with α-ketoglutarate (α-KG) and dimethyl-α-KG (DM-α-KG), which are cosubstrates for TET1 dioxygenase. The treatments with α-KG and DM-α-KG promoted 5hmC formation and malignancy of CCA cells. Molecular and pharmacological approaches were used to inhibit TET1 activity, and these treatments substantially suppressed 5hmC and CCA carcinogenesis. Mechanistically, it was found that knockdown of TET1 may suppress CCA progression by targeting cell growth and apoptosis through epigenetic regulation. Consistently, targeting TET1 significantly inhibited CCA malignant progression in a liver orthotopic xenograft model by targeting cell growth and apoptosis. CONCLUSIONS: Our data suggest that expression of TET1 is highly associated with CCA carcinogenesis. It will be important to evaluate TET1 expression in CCA tumors before application of the IDH1 mutation inhibitor because the inhibitor suppresses 2-hydroxyglutarate expression, which may result in activation of TET, potentially leading to CCA malignancy.

ANOX: A robust computational model for predicting the antioxidant proteins based on multiple features.

As an indispensable component of various living organisms, the antioxidant proteins have been studied for anti-aging and prevention of various diseases, such as altitude sickness, coronary heart disease, and even cancer. However, the traditional experimental methods for identifying the antioxidant proteins are very expensive and time-consuming. Thus, to address the challenge, a new predictor, named ANOX, was developed in this study. Multiple features, such as frequency matrix features (FRE), amino acid and dipeptide composition (AADP), evolutionary difference formula features (EEDP), k-separated bigrams (KSB), and PSI-PRED secondary structure (PRED), were extracted to generate the original feature space. To find the optimized feature subset, the Max-Relevance-Max-Distance (MRMD) algorithm was implemented for feature ranking and our model received the best performance with the top 1170 features. Rigorous tests were performed to evaluate the performance of ANOX, and the results showed that ANOX achieved a major improvement in the prediction accuracy of the antioxidant proteins (AUC:0.930 and 0.935 using 5-fold cross-validation or the jackknife test) compared to the state-of-the-art predictor AOPs-SVM (AUC:0.869 and 0.885). The dataset used in this study and the source code of ANOX are all available at https://github.com/NWAFU-LiuLab/ANOX.

Targeting Aspartate Beta-Hydroxylase with the Small Molecule Inhibitor MO-I-1182 Suppresses Cholangiocarcinoma Metastasis.

BACKGROUND: Cholangiocarcinoma is a devastating disease with a 2% 5-year survival if the disease has spread outside the liver. The enzyme aspartate beta-hydroxylase (ASPH) has been demonstrated to be highly expressed in cholangiocarcinoma but not in normal bile ducts and found to stimulate tumor cell migration. In addition, it was found that targeting ASPH inhibits cholangiocarcinoma malignant progression. However, it is not clear whether targeting ASPH with the small molecule inhibitor MO-I-1182 suppresses cholangiocarcinoma metastasis. The current study aims to study the efficacy of MO-I-1182 in suppressing cholangiocarcinoma metastasis. METHODS: The analysis was performed in vitro and in vivo with a preclinical animal model by using molecular and biochemical strategies to regulate ASPH expression and function. RESULTS: Knockdown of ASPH substantially inhibited cell migration and invasion in two human cholangiocarcinoma cell lines. Targeting ASPH with a small molecule inhibitor suppressed cholangiocarcinoma progression. Molecular mechanism studies demonstrated that knockdown of ASPH subsequently suppressed protein levels of the matrix metalloproteinases. The ASPH knockdown experiments suggest that this enzyme may modulate cholangiocarcinoma metastasis by regulating matrix metalloproteinases expression. Furthermore, using an ASPH inhibitor in a rat cholangiocarcinoma intrahepatic model established with BED-Neu-CL#24 cholangiocarcinoma cells, it was found that targeting ASPH inhibited intrahepatic cholangiocarcinoma metastasis and downstream expression of the matrix metalloproteinases. CONCLUSION: ASPH may modulate cholangiocarcinoma metastasis via matrix metalloproteinases expression. Taken together, targeting ASPH function may inhibit intrahepatic cholangiocarcinoma metastasis and improve survival.

Long non-coding RNA TNRC6C-AS1 promotes methylation of STK4 to inhibit thyroid carcinoma cell apoptosis and autophagy via Hippo signalling pathway.

The role of long non-coding RNAs (lncRNAs) in thyroid carcinoma (TC), the most frequent endocrine malignancy, has been extensively examined. This study investigated effect of interaction among lncRNA TNRC6C-AS1, serine/threonine-protein kinase 4 (STK4) and Hippo signalling pathway on TC. Initially, lncRNA TNRC6C-AS1 expression in TC tissues was detected. To explore roles of lncRNA TNRC6C-AS1, STK4 and Hippo signalling pathway in TC progression, their expressions were altered. Interaction between lncRNA TNRC6C-AS1 and STK4, STK4 promoter methylation, or Hippo signalling pathway was verified. After that, a series of experiments were employed to evaluate in vitro ability of apoptosis, proliferation and autophagy of TC cells and in vivo tumorigenicity, and tumour growth of TC cells. lncRNA TNRC6C-AS1 was highly expressed while STK4 was poorly expressed in TC tissues. LncRNA TNRC6C-AS1 promoted the STK4 methylation and down-regulated STK4 expression, which further activated the Hippo signalling pathway. STK4 silencing was observed to promote the proliferation ability of TC cells, inhibit the apoptosis and autophagy abilities, as well as enhance the tumorigenicity and tumour growth. Moreover, the in vitro proliferation ability as well as the in vivo tumorigenicity and tumour growth of TC cells were inhibited after the blockade of Hippo signalling pathway, while the apoptosis and autophagy abilities were promoted. The results demonstrate that the lncRNA TNRC6C-AS1 increases STK4 promoter methylation to down-regulate STK4 expression, thereby promoting the development of TC through activation of Hippo signalling pathway. It highlights that lncRNA TNRC6C-AS1 may be a novel therapeutic target for the treatment of TC.

Chronic ethanol-mediated hepatocyte apoptosis links to decreased TET1 and 5-hydroxymethylcytosine formation.

The 5-hydroxymethylcytosine (5hmc) is a newly identified epigenetic modification thought to be regulated by the TET family of proteins. Little information is available about how ethanol consumption may modulate 5hmC formation and alcoholic liver disease (ALD) progression. A rat ALD model was used to study 5hmC in relationship to hepatocyte apoptosis. Human ALD liver samples were also used to validate these findings. It was found that chronic ethanol feeding significantly reduced 5hmC formation in a rat ALD model. There were no significant changes in TET2 and TET3 between the control- and ethanol-fed animals. In contrast, methylcytosine dioxygenase TET1 (TET1) expression was substantially reduced in the ethanol-fed rats and was accompanied by increased hepatocyte apoptosis. Similarly, knockdown of TET1 in human hepatocyte-like cells also significantly promoted apoptosis. Down-regulation of TET1 resulted in elevated expression of the DNA damage marker, suggesting a role for 5hmc in hepatocyte DNA damage as well. Mechanistic studies revealed that inhibition of TET1 promoted apoptotic gene expression. Similarly, targeting TET1 activity by removing cosubstrate promoted apoptosis and DNA damage. Furthermore, treatment with 5-azacitidine significantly mimics these effects, suggesting that chronic ethanol consumption promotes hepatocyte apoptosis and DNA damage by diminishing TET1-mediated 5hmC formation and DNA methylation. In summary, the current study provides a novel molecular insight that TET1-mediated 5hmC is involved in hepatocyte apoptosis in ALD progression.-Ji, C., Nagaoka, K., Zou, J., Casulli, S., Lu, S., Cao, K. Y., Zhang, H., Iwagami, Y., Carlson, R. I., Brooks, K., Lawrence, J., Mueller, W., Wands, J. R., Huang, C.-K. Chronic ethanol-mediated hepatocyte apoptosis links to decreased TET1 and 5-hydroxymethylcytosine formation.

A novel DPP6 variant in Chinese families causes early repolarization syndrome.

Previous studies demonstrated that variants in dipeptidyl aminopeptidase-like protein-6 (DPP6) are involved in idiopathic ventricular fibrillation. However, its role in early repolarization syndrome (ERS) remains largely elusive. The aim of this study is to determine whether the novel DPP6-L747P variant is associated with ERS, and explore the underlying mechanisms. In our study, whole genome sequencing was used to identify a genetic variant in 4 Chinese families with sudden cardiac arrest induced by ERS. Then, wild-type (WT) DPP6 or mutant (c.2240T > C/p.L747P) DPP6 were respectively expressed in HEK293 cells, co-expressed with KV4.3 and KChIP2. Western blotting, immunofluorescence, and whole-cell patch clamp experiments were performed to reveal possible underlying mechanisms. A novel missense variant (c.2240T > C/p.L747P) in DPP6 was identified in the 4 families. Both DPP6-WT and DPP6-L747P were mainly located on the cell membrane. Compared with DPP6-WT, the intensity of DPP6 protein bands was downregulated in DPP6-L747P. Functional experiments showed that macroscopic currents exhibited an increase in DPP6-L747P, and the current intensity of DPP6-L747P was increased more than that of DPP6-WT (63.1 ± 8.2 pA/pF vs.86.5 ± 15.1 pA/pF at +50 mV, P < 0.05). Compared with DPP6-WT, the slope of the activation curve of DPP6-L747P was slightly decreased (15.49 ±â€¯0.56 mV vs. 13.88 ±â€¯0.54 mV, P < 0.05), the slope of the inactivation curve was increased (13.65 ±â€¯1.57 mV, vs. 24.44 ±â€¯2.79 mV, P < 0.05) and the recovery time constant was significantly reduced (216.81 ±â€¯18.59 ms vs. 102.11 ±â€¯32.03 ms, P < 0.05). In conclusion, we identified a novel missense variant (c.2240T > C/p. L747P) in DPP6 in 4 Chinese families with sudden cardiac arrest induced by ERS. Patch clamp experiments revealed that this variant could generate a gain of function of Ito and affect the potassium current. These results demonstrated that changes caused by the variant may be the underlying mechanisms of malignant arrhythmias in the individuals with ERS.

Early repolarization pattern associated with coronary artery disease and increased the risk of cardiac death in acute myocardium infarction.

BACKGROUND: Early repolarization pattern (ERP) was associated with sudden cardiac death in recent studies. However, the associations between ERP and coronary artery disease (CAD), and ERP and cardiac death caused by acute myocardial infarction (MI) remains unclear. METHODS: We retrospectively enrolled consecutive 1,545 CAD patients and 908 non-CAD subjects as control group which were confirmed by coronary angiograph. The CAD patients include stable CAD, acute MI patients, and old MI patients. Multivariate logistic regression was employed to evaluate the relationship between ERP and CAD, and ERP and cardiac death caused by acute MI. RESULTS: Of the 1,545 CAD subjects, there were 1,029 stable CAD patients, 404 acute MI patients, and 112 old MI patients. The incidence of ERP was much higher among patients with CAD than without CAD subjects (20.1% vs. 6.2%, p < .001) after adjusting for major cardiovascular risk factors. No significant correlation was observed between lead region of ERP on 12-lead ECG and single abnormal artery. Of the 404 acute MI patients, 342 patients survived and 62 patients died. Incidence of ERP was higher in non-survivor than survivor patients with acute MI (24.2% vs. 17.5%, p = .006) after adjustment for major cardiovascular risk factors. CONCLUSION: The incidence of ERP was higher in CAD patients than subjects without CAD and in non-survivor patients than survivor patients with acute MI. The lead region of ERP on 12-lead ECG was not associated with single abnormal coronary artery.

Mutation in KCNE1 associated to early repolarization syndrome by modulation of slowly activating delayed rectifier K+ current.

BACKGROUND: Recent studies have revealed that mutation in KCNE1, ß-subunits of cardiac potassium channel, involved in ventricular fibrillation. Whereas its role in early repolarization syndrome (ERS) is less well understood. OBJECTIVE: To study whether mutant in KCNE1 is associated with ERS and explore the possible underlying molecular mechanisms. METHODS: Whole genome from four unrelated families with ERS was amplified and sequenced. Wild-type (WT) KCNE1 and/or KCNE1-S38G (S38G) were expressed in HEK293 cells with KCNQ1. Functional studies included whole-cell patch-clamp, western blot and immunofluorescence were performed to reveal the possible underlying mechanisms. RESULTS: The co-expression of KCNE1-S38G and KCNQ1 decreased tail current density of IKs but had little effect in modulation channel kinetics of IKs. Compared with KCNE1-WT, the expression and membrane location of KCNE1-S38G decreased. Co-expression of KCNE1-WT and KCNE1-S38G partially rescued the function of IKs channel. CONCLUSIONS: The S38G mutation induced a loss-of-function of IKs due to decreasing of KCNE1 protein expression and defecting in KCNE1 protein membrane trafficking. Our findings suggested that KCNE1 may be one of the possible modulatory genes associated to ERS.

Alcohol-mediated miR-34a modulates hepatocyte growth and apoptosis.

MicroRNAs (miRs) have been recently shown to be heavily involved in the development of alcoholic liver disease (ALD) and suggested as a potential therapeutic target in ALD. The miR-34a was consistently reported to be significantly elevated in several ALD rodent models, but it remains unclear how miR-34a modulates the cellular behaviours of hepatocytes in ALD development and progression. This study aims to characterize alcohol-induced miR-34a impact on hepatocytes growth and apoptosis. The miRNA array was performed to assess changes in miRNA after chronic alcohol feeding. Liver and blood samples were used to examine ALD progression. The miR-34a was overexpressed in human hepatocytes to evaluate its impact on cell growth and apoptosis. Real-time quantitative PCR and Western blot were used to determine the growth and apoptosis molecular signalling pathways associated with miR-34a. Alcohol feeding significantly promoted fatty liver progression, serum ALT levels, apoptosis and miR-34a expression in rat liver. Overexpression of miR-34a in human hepatocytes suppressed cell growth signallings, including c-Met, cyclin D1 and cyclin-dependent kinase 6 (CDK6). The miR-34a might also inhibit the expression of sirtuin 1 (Sirt1) and its target, B-cell lymphoma 2. Interestingly, the expression of miR-34a reverses the suppressive effects of ethanol on cell growth. But, miR-34a promotes hepatocyte senescence and apoptosis. Although the miR-34a-mediated down-regulation of cell growth-associated genes may contribute to cell growth retardation, other miR-34a targets, such as Sirt1, may reverse this phenotype. Future studies will be needed to clarify the role of miR-34a in ALD progression.

SCN1Bß mutations that affect their association with Kv4.3 underlie early repolarization syndrome.

BACKGROUND: Abnormal cardiac ion channels current, including transient outward potassium current (Ito ), is associated with early repolarization syndrome (ERS). Previous studies showed that mutations in SCN1Bß both to increase the Ito current and to decrease the sodium current. Yet its role in ERS remains unknown. OBJECTIVE: To determine the role of mutations in the SCN1Bß subunits in ERS. METHODS: We screened for mutations in the SCN1B genes from four families with ERS. Wild-type and mutant SCN1Bß genes were co-expressed with wild-type KCND3 in human embryonic kidney cells (HEK293). Whole-cell patch-clamp technique and co-immunoprecipitation were used to study the electrophysiological properties and explore the underlying mechanisms. RESULTS: S248R and R250T mutations in SCN1Bß were detected in 4 families' probands. Neither S248R nor R250T mutation had significant influence on the sodium channel current density (INa ) when co-expressed with SCN5A/WT. Co-expression of KCND3/WT and SCN1Bß/S248R or SCN1Bß/R250T increased the transient outward potassium current Ito by 27.44% and 199.89%, respectively (P < 0.05 and P < 0.01, respectively) when compared with SCN1Bß/WT. Electrophysiological properties showed that S248R and R250T mutations decreased the steady-state inactivation and recovery from inactivation of Ito channel. Co-immunoprecipitation study demonstrated an increased association between SCN1Bß mutations and Kv4.3 compared with SCN1Bß/WT (P < 0.05 and P < 0.01, respectively). CONCLUSION: The S248R and R250T mutations of SCN1Bß gene caused gain-of-function of Ito by associated with Kv4.3, which maybe underlie the ERS phenotype of the probands.

A Heterozygous Missense hERG Mutation Associated with Early Repolarization Syndrome.

BACKGROUND/AIMS: Early repolarization syndrome (ERS) has been recently recognized as early repolarization pattern with idiopathic ventricular fibrillation. However, the genetic background of ERS has not been fully understood. METHODS: A Chinese family with sudden cardiac death associated with ERS was investigated. Direct sequencing of ERS susceptibility genes was performed on the proband and family members. Whole-cell patch-clamp methods were used to characterize the mutant channel expressed in HEK 293 cells. RESULTS: One missense mutation (p. K801T) was found in the hERG (KCNH2 gene) by the direct sequencing of candidate genes. Whole cell voltage clamp studies of the K801T mutation in HEK 293 cells demonstrated a 1.5-fold increase in maximum steady state current (37.2±7.3 vs 20.3±4.4 pA/pF) that occurred at a 20 mV more positive potential compared to the wild type channels. The voltage dependence of inactivation was significantly shifted in the positive voltage direction (WT -59.5±1.4 vs K801T -44.3±1.2 mV). Kinetic analysis revealed slower inactivation rates of K801T, but faster rates of activation and deactivation. The hERG channel blockers tested inhibited K801T-hERG channel in concentration response, and the potencies of these drugs can be rank-ordered as follows: quinidine> disopyramide> sotalol> flecainide. CONCLUSION: Our study indicated that the K801T mutation caused the gain of function of hERG channels that may account for the clinical phenotype of ERS. Quinidine and disopyramide could improve the function of K801T-hERG mutant channel, and may be therapeutic options for patients with the K801T hERG mutation.