Acetylcholine Reduces IKr and Prolongs Action Potentials in Human Ventricular Cardiomyocytes

Vagal nerve stimulation (VNS) has a meaningful basis as a potentially effective treatment for heart failure with reduced ejection fraction. There is an ongoing VNS randomized study, and four studies are completed. However, relatively little is known about the effect of acetylcholine (ACh) on repolarization in human ventricular cardiomyocytes, as well as the effect of ACh on the rapid component of the delayed rectifier K(+) current (I(Kr)). Here, we investigated the effect of ACh on the action potential parameters in human ventricular preparations and on I(Kr) in human induced pluripotent stem-cell-derived cardiomyocytes (hiPSC-CMs). Using standard microelectrode technique, we demonstrated that ACh (5 µM) significantly increased the action potential duration in human left ventricular myocardial slices. ACh (5 µM) also prolonged repolarization in a human Purkinje fiber and a papillary muscle. Optical mapping revealed that ACh increased the action potential duration in human left ventricular myocardial slices and that the effect was dose-dependent. Perforated patch clamp experiments demonstrated action potential prolongation and a significant decrease in I(Kr) by ACh (5 µM) in hiPSC-CMs. Computer simulations of the electrical activity of a human ventricular cardiomyocyte showed an increase in action potential duration upon implementation of the experimentally observed ACh-induced changes in the fully activated conductance and steady-state activation of I(Kr). Our findings support the hypothesis that ACh can influence the repolarization in human ventricular cardiomyocytes by at least changes in I(Kr)

The Capsid Protein of Hepatitis E Virus Inhibits Interferon Induction via Its N-Terminal Arginine-Rich Motif

Hepatitis E virus (HEV) causes predominantly acute and self-limiting hepatitis. However, in HEV-infected pregnant women, the case fatality rate because of fulminant hepatitis can be up to 30%. HEV infection is zoonotic for some genotypes. The HEV genome contains three open reading frames: ORF1 encodes the non-structural polyprotein involved in viral RNA replication; ORF2 encodes the capsid protein; ORF3 encodes a small multifunctional protein. Interferons (IFNs) play a significant role in the early stage of the host antiviral response. In this study, we discovered that the capsid protein antagonizes IFN induction. Mechanistically, the capsid protein blocked the phosphorylation of IFN regulatory factor 3 (IRF3) via interaction with the multiprotein complex consisting of mitochondrial antiviral-signaling protein (MAVS), TANK-binding kinase 1 (TBK1), and IRF3. The N-terminal domain of the capsid protein was found to be responsible for the inhibition of IRF3 activation. Further study showed that the arginine-rich-motif in the N-terminal domain is indispensable for the inhibition as mutations of any of the arginine residues abolished the blockage of IRF3 phosphorylation. These results provide further insight into HEV interference with the host innate immunity.https://doi.org/10.3390/v1111105

A Linear Surface Epitope in a Proline-Rich Region of ORF3 Product of Genotype 1 Hepatitis E Virus

Hepatitis E virus (HEV) is one of the viral pathogens causing hepatitis in humans. HEV open reading frame 3 (ORF3) encodes a small multifunctional protein (VP13), which is essential for HEV infection. In this study, a linear epitope was identified in a polyproline (PXXP) motif from VP13 of genotype 1 HEV by using a monoclonal antibody. The epitope was detected in enzyme-linked immunosorbent assay (ELISA), immunoblotting and immunofluorescence assays. Epitope mapping showed that the epitope locates in a proline-rich region containing a PXXP motif in amino acid residues 66-75 of VP13. The epitope was also detected in HEV-infected liver cells and reacted with genotype 1-specific antibodies in an HEV-positive human serum sample. The results demonstrated that the epitope in the PXXP motif of the genotype 1 VP13 is linear and surface-oriented, which should facilitate in-depth studies on the viral protein and HEV biology

The Capsid Protein of Hepatitis E Virus Inhibits Interferon Induction via Its N-Terminal Arginine-Rich Motif

Hepatitis E virus (HEV) causes predominantly acute and self-limiting hepatitis. However, in HEV-infected pregnant women, the case fatality rate because of fulminant hepatitis can be up to 30%. HEV infection is zoonotic for some genotypes. The HEV genome contains three open reading frames: ORF1 encodes the non-structural polyprotein involved in viral RNA replication; ORF2 encodes the capsid protein; ORF3 encodes a small multifunctional protein. Interferons (IFNs) play a significant role in the early stage of the host antiviral response. In this study, we discovered that the capsid protein antagonizes IFN induction. Mechanistically, the capsid protein blocked the phosphorylation of IFN regulatory factor 3 (IRF3) via interaction with the multiprotein complex consisting of mitochondrial antiviral-signaling protein (MAVS), TANK-binding kinase 1 (TBK1), and IRF3. The N-terminal domain of the capsid protein was found to be responsible for the inhibition of IRF3 activation. Further study showed that the arginine-rich-motif in the N-terminal domain is indispensable for the inhibition as mutations of any of the arginine residues abolished the blockage of IRF3 phosphorylation. These results provide further insight into HEV interference with the host innate immunity

Stretchable and Transparent Metal Nanowire Microelectrodes for Simultaneous Electrophysiology and Optogenetics Applications

Recently developed optically transparent microelectrode technology provides a promising approach for simultaneous high-resolution electrical and optical biointerfacing with tissues in vivo and in vitro. A critically unmet need is designing high-performance stretchable platforms for conformal biointerfacing with mechanically active organs. Here, we report silver nanowire (Ag NW) stretchable transparent microelectrodes and interconnects that exhibit excellent electrical and electrochemical performance, high optical transparency, superior mechanical robustness and durability by a simple selective-patterning process. The fabrication method allows the direct integration of Ag NW networks on elastomeric substrates. The resulting Ag NW interface exhibits a low sheet resistance (Rsh) of 1.52–4.35 Ω sq−1, an advantageous normalized electrochemical impedance of 3.78–6.04 Ω cm2, a high optical transparency of 61.3–80.5% at 550 nm and a stretchability of 40%. The microelectrode arrays (MEAs) fabricated with this approach exhibit uniform electrochemical performance across all channels. Studies on mice demonstrate that both pristine and stretched Ag NW microelectrodes can achieve high-fidelity electrophysiological monitoring of cardiac activity with/without co-localized optogenetic pacing. Together, these results pave the way for developing stretchable and transparent metal nanowire networks for high-resolution opto-electric biointerfacing with mechanically active organs, such as the heart

A Linear Surface Epitope in a Proline-Rich Region of ORF3 Product of Genotype 1 Hepatitis E Virus

Hepatitis E virus (HEV) is one of the viral pathogens causing hepatitis in humans. HEV open reading frame 3 (ORF3) encodes a small multifunctional protein (VP13), which is essential for HEV infection. In this study, a linear epitope was identified in a polyproline (PXXP) motif from VP13 of genotype 1 HEV by using a monoclonal antibody. The epitope was detected in enzyme-linked immunosorbent assay (ELISA), immunoblotting and immunofluorescence assays. Epitope mapping showed that the epitope locates in a proline-rich region containing a PXXP motif in amino acid residues 66-75 of VP13. The epitope was also detected in HEV-infected liver cells and reacted with genotype 1-specific antibodies in an HEV-positive human serum sample. The results demonstrated that the epitope in the PXXP motif of the genotype 1 VP13 is linear and surface-oriented, which should facilitate in-depth studies on the viral protein and HEV biology

Fiber spectrum analyzer based on planar waveguide array aligned to a camera without lens

We propose and experimentally demonstrate a fiber spectrum analyzer based on a planar waveguide chip butt-coupled with an input fiber and aligned to a standard camera without any free-space optical elements. The chip consists of a single-mode waveguide to connect with the fiber, a beam broadening area, and a waveguide array in which the lengths of the waveguides are designed for both wavelength separation and beam focusing. The facet of the chip is diced open so that the outputs of the array form a near-field emitter. The far field are calculated by the Rayleigh-Sommerfeld diffraction integral. We show that the chip can provide a focal depth on the millimeter scale, allowing relaxed alignment to the camera without any fine-positioning stage. Two devices with 120 and 220 waveguides are fabricated on the polymer waveguide platform. The measured spectral width are 0.63 nm and 0.42 nm, respectively. This simple and practical approach may lead to the development of a spectrum analyzer for fiber that is easily mountable to any commercial camera, thereby avoiding the complication for customized detectors as well as electronic circuits afterwards

Zika virus NS5 protein antagonizes type I interferon production via blocking TBK1 activation

Zika virus (ZIKV) is a mosquito-borne positive-sense single-stranded RNA virus in the family of Flaviviridae. Unlike other flaviviruses, ZIKV infection of pregnant women may result in birth defects in their newborns, such as microcephaly or vision problem. ZIKV is known to antagonize the interferon (IFN) production in infected cells. However, the exact mechanism of this interference is not fully understood. Here, we demonstrate that NS5 protein of ZIKV MR766 strain antagonizes IFN production through inhibiting the activation of TANK-binding kinase 1 (TBK1), which phosphorylates the transcription activator IFN regulatory factor 3 (IRF3). Mechanistically, NS5 interacts with the ubiquitin-like domain of TBK1 and results in less complex of TBK1 and TNF (tumor necrosis factor) receptor-associated factor 6 (TRAF6), leading to dampened TBK1 activation and IRF3 phosphorylation. Our study provides insights into the mechanism of ZIKV evasion of IFN-mediated innate immunity