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Dates J, Kolosov D. Voltage-gated ion channels as novel regulators of epithelial ion transport in the osmoregulatory organs of insects. FRONTIERS IN INSECT SCIENCE 2024; 4:1385895. [PMID: 38835480 PMCID: PMC11148248 DOI: 10.3389/finsc.2024.1385895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2024] [Accepted: 05/01/2024] [Indexed: 06/06/2024]
Abstract
Voltage-gated ion channels (VGICs) respond to changes in membrane potential (Vm) and typically exhibit fast kinetic properties. They play an important role in signal detection and propagation in excitable tissues. In contrast, the role of VGICs in non-excitable tissues like epithelia is less studied and less clear. Studies in epithelia of vertebrates and invertebrates demonstrate wide expression of VGICs in epithelia of animals. Recently, VGICs have emerged as regulators of ion transport in the Malpighian tubules (MTs) and other osmoregulatory organs of insects. This mini-review aims to concisely summarize which VGICs have been implicated in the regulation of ion transport in the osmoregulatory epithelia of insects to date, and highlight select groups for further study. We have also speculated on the roles VGICs may potentially play in regulating processes connected directly to ion transport in insects (e.g., acid-base balance, desiccation, thermal tolerance). This review is not meant to be exhaustive but should rather serve as a thought-provoking collection of select existing highlights on VGICs, and to emphasize how understudied this mechanism of ion transport regulation is in insect epithelia.
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Affiliation(s)
- Jocelyne Dates
- Department of Biological Sciences, California State University San Marcos, San Marcos, CA, United States
| | - Dennis Kolosov
- Department of Biological Sciences, California State University San Marcos, San Marcos, CA, United States
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Dowdy T, Vilamu HM, Lita A, Li A, Yamasaki T, Zhang L, Chari R, Song H, Zhang M, Zhang W, Briceno N, Davis D, Gilbert MR, Larion M. Targeting the sphingolipid rheostat in IDH1 mut glioma alters cholesterol homeostasis and triggers apoptosis via membrane degradation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.26.591321. [PMID: 38903071 PMCID: PMC11188108 DOI: 10.1101/2024.04.26.591321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/22/2024]
Abstract
The cross-regulation of metabolism and trafficking is not well understood for the vital sphingolipids and cholesterol constituents of cellular compartments. While reports are starting to surface on how sphingolipids like sphingomyelin (SM) dysregulate cholesterol levels in different cellular compartments (Jiang et al., 2022), limited research is available on the mechanisms driving the relationship between sphingolipids and cholesterol homeostasis, or its biological implications. Previously, we have identified sphingolipid metabolism as a unique vulnerability for IDH1 mut gliomas via a rational drug design. Herein, we show how modulating sphingolipid levels affects cholesterol homeostasis in brain tumors. However, we unexpectedly discovered for the first time that C17 sphingosine and NDMS addition to cancer cells alters cholesterol homeostasis by impacting its cellular synthesis, uptake, and efflux leading to a net decrease in cholesterol levels and inducing apoptosis. Our results reflect a reverse correlation between the levels of sphingosines, NDMS, and unesterified, free cholesterol in the cells. We show that increasing sphingosine and NDMS (a sphingosine analog) levels alter not only the trafficking of cholesterol between membranes but also the efflux and synthesis of cholesterol. We also demonstrate that despite the effort to remove free cholesterol by ABCA1-mediated efflux or by suppressing machinery for the influx (LDLR) and biosynthetic pathway (HMGCR), apoptosis is inevitable for IDH1 mut glioma cells. This is the first study that shows how altering sphingosine levels directly affects cholesterol homeostasis in cancer cells and can be used to manipulate this relationship to induce apoptosis in IDH1 mut gliomas.
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Moura ACM, Asare IK, Cruz MF, Aguado AJF, Tuck KD, Campbell CC, Scheyer MW, Obaseki I, Alston S, Kravats AN, Sanders CR, Lorigan GA, Sahu ID. Studying Conformational Properties of Transmembrane Domain of KCNE3 in a Lipid Bilayer Membrane Using Molecular Dynamics Simulations. MEMBRANES 2024; 14:45. [PMID: 38392672 PMCID: PMC10890134 DOI: 10.3390/membranes14020045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Revised: 01/22/2024] [Accepted: 01/29/2024] [Indexed: 02/24/2024]
Abstract
KCNE3 is a single-pass integral membrane protein that regulates numerous voltage-gated potassium channel functions such as KCNQ1. Previous solution NMR studies suggested a moderate degree of curved α-helical structure in the transmembrane domain (TMD) of KCNE3 in lyso-myristoylphosphatidylcholine (LMPC) micelles and isotropic bicelles with the residues T71, S74 and G78 situated along the concave face of the curved helix. During the interaction of KCNE3 and KCNQ1, KCNE3 pushes its transmembrane domain against KCNQ1 to lock the voltage sensor in its depolarized conformation. A cryo-EM study of KCNE3 complexed with KCNQ1 in nanodiscs suggested a deviation of the KCNE3 structure from its independent structure in isotropic bicelles. Despite the biological significance of KCNE3 TMD, the conformational properties of KCNE3 are poorly understood. Here, all atom molecular dynamics (MD) simulations were utilized to investigate the conformational dynamics of the transmembrane domain of KCNE3 in a lipid bilayer containing a mixture of POPC and POPG lipids (3:1). Further, the effect of the interaction impairing mutations (V72A, I76A and F68A) on the conformational properties of the KCNE3 TMD in lipid bilayers was investigated. Our MD simulation results suggest that the KCNE3 TMD adopts a nearly linear α helical structural conformation in POPC-POPG lipid bilayers. Additionally, the results showed no significant change in the nearly linear α-helical conformation of KCNE3 TMD in the presence of interaction impairing mutations within the sampled time frame. The KCNE3 TMD is more stable with lower flexibility in comparison to the N-terminal and C-terminal of KCNE3 in lipid bilayers. The overall conformational flexibility of KCNE3 also varies in the presence of the interaction-impairing mutations. The MD simulation data further suggest that the membrane bilayer width is similar for wild-type KCNE3 and KCNE3 containing mutations. The Z-distance measurement data revealed that the TMD residue site A69 is close to the lipid bilayer center, and residue sites S57 and S82 are close to the surfaces of the lipid bilayer membrane for wild-type KCNE3 and KCNE3 containing interaction-impairing mutations. These results agree with earlier KCNE3 biophysical studies. The results of these MD simulations will provide complementary data to the experimental outcomes of KCNE3 to help understand its conformational dynamic properties in a more native lipid bilayer environment.
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Affiliation(s)
| | - Isaac K Asare
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA
| | - Mateo Fernandez Cruz
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA
| | | | - Kaeleigh Dyan Tuck
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA
| | - Conner C Campbell
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA
| | - Matthew W Scheyer
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA
| | - Ikponwmosa Obaseki
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Steve Alston
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA
| | - Andrea N Kravats
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Charles R Sanders
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University, Nashville, TN 37232, USA
| | - Gary A Lorigan
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Indra D Sahu
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
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4
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Lai H, Gao M, Yang H. The potassium channels: Neurobiology and pharmacology of tinnitus. J Neurosci Res 2024; 102:e25281. [PMID: 38284861 DOI: 10.1002/jnr.25281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2023] [Revised: 10/27/2023] [Accepted: 11/16/2023] [Indexed: 01/30/2024]
Abstract
Tinnitus is a widespread public health issue that imposes a significant social burden. The occurrence and maintenance of tinnitus have been shown to be associated with abnormal neuronal activity in the auditory pathway. Based on this view, neurobiological and pharmacological developments in tinnitus focus on ion channels and synaptic neurotransmitter receptors in neurons in the auditory pathway. With major breakthroughs in the pathophysiology and research methodology of tinnitus in recent years, the role of the largest family of ion channels, potassium ion channels, in modulating the excitability of neurons involved in tinnitus has been increasingly demonstrated. More and more potassium channels involved in the neural mechanism of tinnitus have been discovered, and corresponding drugs have been developed. In this article, we review animal (mouse, rat, hamster, and guinea-pig), human, and genetic studies on the different potassium channels involved in tinnitus, analyze the limitations of current clinical research on potassium channels, and propose future prospects. The aim of this review is to promote the understanding of the role of potassium ion channels in tinnitus and to advance the development of drugs targeting potassium ion channels for tinnitus.
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Affiliation(s)
- Haohong Lai
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
| | - Minqian Gao
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
- Department of Hearing and Speech-Language Science, Guangzhou Xinhua University, Guangzhou, China
| | - Haidi Yang
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou, China
- Department of Hearing and Speech-Language Science, Guangzhou Xinhua University, Guangzhou, China
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Yamanouchi D, Kasuya G, Nakajo K, Kise Y, Nureki O. Dual allosteric modulation of voltage and calcium sensitivities of the Slo1-LRRC channel complex. Mol Cell 2023; 83:4555-4569.e4. [PMID: 38035882 DOI: 10.1016/j.molcel.2023.11.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2022] [Revised: 09/15/2023] [Accepted: 11/06/2023] [Indexed: 12/02/2023]
Abstract
Modulation of large conductance intracellular ligand-activated potassium (BK) channel family (Slo1-3) by auxiliary subunits allows diverse physiological functions in excitable and non-excitable cells. Cryoelectron microscopy (cryo-EM) structures of voltage-gated potassium (Kv) channel complexes have provided insights into how voltage sensitivity is modulated by auxiliary subunits. However, the modulation mechanisms of BK channels, particularly as ligand-activated ion channels, remain unknown. Slo1 is a Ca2+-activated and voltage-gated BK channel and is expressed in neurons, muscle cells, and epithelial cells. Using cryo-EM and electrophysiology, we show that the LRRC26-γ1 subunit modulates not only voltage but also Ca2+ sensitivity of Homo sapiens Slo1. LRRC26 stabilizes the active conformation of voltage-senor domains of Slo1 by an extracellularly S4-locking mechanism. Furthermore, it also stabilizes the active conformation of Ca2+-sensor domains of Slo1 intracellularly, which is functionally equivalent to intracellular Ca2+ in the activation of Slo1. Such a dual allosteric modulatory mechanism may be general in regulating the intracellular ligand-activated BK channel complexes.
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Affiliation(s)
- Daichi Yamanouchi
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Go Kasuya
- Division of Integrative Physiology, Department of Physiology, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke-shi, Tochigi 329-0498, Japan.
| | - Koichi Nakajo
- Division of Integrative Physiology, Department of Physiology, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke-shi, Tochigi 329-0498, Japan
| | - Yoshiaki Kise
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
| | - Osamu Nureki
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
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Scheyer MW, Campbell C, William PL, Hussain M, Begum A, Fonseca SE, Asare IK, Dabney P, Dabney-Smith C, Lorigan GA, Sahu ID. Electron paramagnetic resonance spectroscopic characterization of the human KCNE3 protein in lipodisq nanoparticles for structural dynamics of membrane proteins. Biophys Chem 2023; 301:107080. [PMID: 37531799 DOI: 10.1016/j.bpc.2023.107080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 07/07/2023] [Accepted: 07/24/2023] [Indexed: 08/04/2023]
Abstract
One of the major challenges in solubilization of membrane proteins is to find the optimal physiological environment for their biophysical studies. EPR spectroscopy is a powerful biophysical technique for studying the structural and dynamic properties of macromolecules. However, the challenges in the membrane protein sample preparation and flexible motion of the spin label limit the utilization of EPR spectroscopy to a majority of membrane protein systems in a physiological membrane-bound state. Recently, lipodisq nanoparticles or styrene-maleic acid copolymer-lipid nanoparticles (SMALPs) have emerged as a membrane mimetic system for investigating the structural studies of membrane proteins. However, its detail characterization for membrane protein studies is still poorly understood. Recently, we characterized the potassium channel membrane protein KCNQ1 voltage sensing domain (KCNQ1-VSD) and KCNE1 reconstituted into lipodisq nanoparticles using EPR spectroscopy. In this study, the potassium channel accessory protein KCNE3 containing flexible N- and C-termini was encapsulated into proteoliposomes and lipodisq nanoparticles and characterized for studying its structural and dynamic properties using nitroxide based site-directed spin labeling EPR spectroscopy. CW-EPR lineshape analysis data indicated an increase in spectral line broadenings with the addition of the styrene-maleic acid (SMA) polymer which approaches close to the rigid limit providing a homogeneous stabilization of the protein-lipid complex. Similarly, EPR DEER measurements indicated an enhanced quality of distance measurements with an increase in the phase memory time (Tm) values upon incorporation of the sample into lipodisq nanoparticles, when compared to proteoliposomes. These results agree with the solution NMR structural structure of the KCNE3 and EPR studies of other membrane proteins in lipodisq nanoparticles. This study along with our earlier studies will provide the reference characterization data that will provide benefit to the membrane protein researchers for studying structural dynamics of challenging membrane proteins.
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Affiliation(s)
- Matthew W Scheyer
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA
| | - Conner Campbell
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA
| | - Patrick L William
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA
| | - Mustakim Hussain
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA
| | - Afsana Begum
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA
| | | | - Isaac K Asare
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA
| | - Peyton Dabney
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA
| | - Carole Dabney-Smith
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Gary A Lorigan
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA
| | - Indra D Sahu
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA; Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA.
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7
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Huang S, Li Y, Shen J, Liang W, Li C. Identification of a diagnostic model and molecular subtypes of major depressive disorder based on endoplasmic reticulum stress-related genes. Front Psychiatry 2023; 14:1168516. [PMID: 37649561 PMCID: PMC10464956 DOI: 10.3389/fpsyt.2023.1168516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Accepted: 08/03/2023] [Indexed: 09/01/2023] Open
Abstract
Subject Major depressive disorder (MDD) negatively affects patients' behaviours and daily lives. Due to the high heterogeneity and complex pathological features of MDD, its diagnosis remains challenging. Evidence suggests that endoplasmic reticulum stress (ERS) is involved in the pathogenesis of MDD; however, relevant diagnostic markers have not been well studied. This study aimed to screen for ERS genes with potential diagnostic value in MDD. Methods Gene expression data on MDD samples were downloaded from the GEO database, and ERS-related genes were obtained from the GeneCards and MSigDB databases. Differentially expressed genes (DEGs) in MDD patients and healthy subjects were identified and then integrated with ERS genes. ERS diagnostic model and nomogram were developed based on biomarkers screened using the LASSO method. The diagnostic performance of this model was evaluated. ERS-associated subtypes were identified. CIBERSORT and GSEA were used to explore the differences between the different subtypes. Finally, WGCNA was performed to identify hub genes related to the subtypes. Results A diagnostic model was developed based on seven ERS genes: KCNE1, PDIA4, STAU1, TMED4, MGST1, RCN1, and SHC1. The validation analysis showed that this model had a good diagnostic performance. KCNE1 expression was positively correlated with M0 macrophages and negatively correlated with resting CD4+ memory T cells. Two subtypes (SubA and SubB) were identified, and these two subtypes showed different ER score. The SubB group showed higher immune infiltration than the SubA group. Finally, NCF4, NCF2, CSF3R, and FPR2 were identified as hub genes associated with ERS molecular subtypes. Conclusion Our current study provides novel diagnostic biomarkers for MDD from an ERS perspective, and these findings further facilitate the use of precision medicine in MDD.
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Affiliation(s)
- Shuwen Huang
- Research Base of Chinese Medicine Syndrome, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian, China
- FuJian Key Laboratory of TCM Health State, Fuzhou, Fujian, China
| | - Yong Li
- Research Base of Chinese Medicine Syndrome, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian, China
- FuJian Key Laboratory of TCM Health State, Fuzhou, Fujian, China
| | - Jianying Shen
- Research Base of Chinese Medicine Syndrome, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian, China
- FuJian Key Laboratory of TCM Health State, Fuzhou, Fujian, China
| | - Wenna Liang
- Research Base of Chinese Medicine Syndrome, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian, China
- FuJian Key Laboratory of TCM Health State, Fuzhou, Fujian, China
| | - Candong Li
- Research Base of Chinese Medicine Syndrome, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian, China
- FuJian Key Laboratory of TCM Health State, Fuzhou, Fujian, China
- LI Candong Qihuang Scholar Studio, Fujian University of Traditional Chinese Medicine, Fuzhou, Fujian, China
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Venkat V, Abdelhalim H, DeGroat W, Zeeshan S, Ahmed Z. Investigating genes associated with heart failure, atrial fibrillation, and other cardiovascular diseases, and predicting disease using machine learning techniques for translational research and precision medicine. Genomics 2023; 115:110584. [PMID: 36813091 DOI: 10.1016/j.ygeno.2023.110584] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Revised: 02/06/2023] [Accepted: 02/11/2023] [Indexed: 02/22/2023]
Abstract
Cardiovascular disease (CVD) is the leading cause of mortality and loss of disability adjusted life years (DALYs) globally. CVDs like Heart Failure (HF) and Atrial Fibrillation (AF) are associated with physical effects on the heart muscles. As a result of the complex nature, progression, inherent genetic makeup, and heterogeneity of CVDs, personalized treatments are believed to be critical. Rightful application of artificial intelligence (AI) and machine learning (ML) approaches can lead to new insights into CVDs for providing better personalized treatments with predictive analysis and deep phenotyping. In this study we focused on implementing AI/ML techniques on RNA-seq driven gene-expression data to investigate genes associated with HF, AF, and other CVDs, and predict disease with high accuracy. The study involved generating RNA-seq data derived from the serum of consented CVD patients. Next, we processed the sequenced data using our RNA-seq pipeline and applied GVViZ for gene-disease data annotation and expression analysis. To achieve our research objectives, we developed a new Findable, Accessible, Intelligent, and Reproducible (FAIR) approach that includes a five-level biostatistical evaluation, primarily based on the Random Forest (RF) algorithm. During our AI/ML analysis, we have fitted, trained, and implemented our model to classify and distinguish high-risk CVD patients based on their age, gender, and race. With the successful execution of our model, we predicted the association of highly significant HF, AF, and other CVDs genes with demographic variables.
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Affiliation(s)
- Vignesh Venkat
- Rutgers Institute for Health, Health Care Policy and Aging Research, Rutgers University, 112 Paterson St, New Brunswick, NJ, USA
| | - Habiba Abdelhalim
- Rutgers Institute for Health, Health Care Policy and Aging Research, Rutgers University, 112 Paterson St, New Brunswick, NJ, USA
| | - William DeGroat
- Rutgers Institute for Health, Health Care Policy and Aging Research, Rutgers University, 112 Paterson St, New Brunswick, NJ, USA
| | - Saman Zeeshan
- Rutgers Cancer Institute of New Jersey, Rutgers University, 195 Little Albany St, New Brunswick, NJ, USA
| | - Zeeshan Ahmed
- Rutgers Institute for Health, Health Care Policy and Aging Research, Rutgers University, 112 Paterson St, New Brunswick, NJ, USA; Department of Medicine, Robert Wood Johnson Medical School, Rutgers Biomedical and Health Sciences, 125 Paterson St, New Brunswick, NJ, USA.
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Campbell C, Faleel FDM, Scheyer MW, Haralu S, Williams PL, Carbo WD, Wilson-Taylor AS, Patel NH, Sanders CR, Lorigan GA, Sahu ID. Comparing the structural dynamics of the human KCNE3 in reconstituted micelle and lipid bilayered vesicle environments. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2022; 1864:183974. [PMID: 35716725 DOI: 10.1016/j.bbamem.2022.183974] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2021] [Revised: 05/12/2022] [Accepted: 05/25/2022] [Indexed: 06/15/2023]
Abstract
KCNE3 is a single transmembrane protein of the KCNE family that modulates the function and trafficking of several voltage-gated potassium channels, including KCNQ1. Structural studies of KCNE3 have been previously conducted in a wide range of model membrane mimics. However, it is important to assess the impact of the membrane mimics used on the observed conformation and dynamics. In this study, we have optimized a method for the reconstitution of the KCNE3 into POPC/POPG lipid bilayer vesicles for electron paramagnetic resonance (EPR) spectroscopy. Our CD spectroscopic data suggested that the degree of regular secondary structure for KCNE3 protein reconstituted into lipid bilayered vesicle is significantly higher than in DPC detergent micelles. Electron paramagnetic resonance (EPR) spectroscopy in combination with site-directed spin labeling (SDSL) was used to probe the structural dynamics of S49C, M59C, L67C, V85C, and S101C mutations of KCNE3 in both DPC micelles and in POPC/POPG lipid bilayered vesicles. Our CW-EPR power saturation data suggested that the site S74C is buried inside the lipid bilayered membrane while the site V85C is located outside the membrane, in contrast to DPC micelle results. These results suggest that the KCNE3 micelle structures need to be refined using data obtained in the lipid bilayered vesicles in order to ascertain the native structure of KCNE3. This work will provide guidelines for detailed structural studies of KCNE3 in a more native membrane environment and comparing the lipid bilayer results to the isotropic bicelle structure and to the KCNQ1-bound cryo-EM structure.
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Affiliation(s)
- Conner Campbell
- Natural Science Division, Campbellsville University, Campbellsville, KY, United States of America
| | | | - Matthew W Scheyer
- Natural Science Division, Campbellsville University, Campbellsville, KY, United States of America
| | - Samuel Haralu
- Natural Science Division, Campbellsville University, Campbellsville, KY, United States of America
| | - Patrick L Williams
- Natural Science Division, Campbellsville University, Campbellsville, KY, United States of America
| | - William David Carbo
- Natural Science Division, Campbellsville University, Campbellsville, KY, United States of America
| | | | - Nima H Patel
- Natural Science Division, Campbellsville University, Campbellsville, KY, United States of America
| | - Charles R Sanders
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University, Nashville, TN, United States of America
| | - Gary A Lorigan
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH, United States of America
| | - Indra D Sahu
- Natural Science Division, Campbellsville University, Campbellsville, KY, United States of America; Department of Chemistry and Biochemistry, Miami University, Oxford, OH, United States of America.
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Abbott GW. Kv Channel Ancillary Subunits: Where Do We Go from Here? Physiology (Bethesda) 2022; 37:0. [PMID: 35797055 PMCID: PMC9394777 DOI: 10.1152/physiol.00005.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/29/2022] [Accepted: 04/29/2022] [Indexed: 01/10/2023] Open
Abstract
Voltage-gated potassium (Kv) channels each comprise four pore-forming α-subunits that orchestrate essential duties such as voltage sensing and K+ selectivity and conductance. In vivo, however, Kv channels also incorporate regulatory subunits-some Kv channel specific, others more general modifiers of protein folding, trafficking, and function. Understanding all the above is essential for a complete picture of the role of Kv channels in physiology and disease.
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Affiliation(s)
- Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California
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11
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Ahmad B, Skorska A, Wolfien M, Sadraddin H, Lemcke H, Vasudevan P, Wolkenhauer O, Steinhoff G, David R, Gaebel R. The Effects of Hypoxic Preconditioned Murine Mesenchymal Stem Cells on Post-Infarct Arrhythmias in the Mouse Model. Int J Mol Sci 2022; 23:ijms23168843. [PMID: 36012110 PMCID: PMC9408396 DOI: 10.3390/ijms23168843] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 08/04/2022] [Accepted: 08/05/2022] [Indexed: 11/16/2022] Open
Abstract
Ventricular arrhythmias associated with myocardial infarction (MI) have a significant impact on mortality in patients following heart attack. Therefore, targeted reduction of arrhythmia represents a therapeutic approach for the prevention and treatment of severe events after infarction. Recent research transplanting mesenchymal stem cells (MSC) showed their potential in MI therapy. Our study aimed to investigate the effects of MSC injection on post-infarction arrhythmia. We used our murine double infarction model, which we previously established, to more closely mimic the clinical situation and intramyocardially injected hypoxic pre-conditioned murine MSC to the infarction border. Thereafter, various types of arrhythmias were recorded and analyzed. We observed a homogenous distribution of all types of arrhythmias after the first infarction, without any significant differences between the groups. Yet, MSC therapy after double infarction led to a highly significant reduction in simple and complex arrhythmias. Moreover, RNA-sequencing of samples from stem cell treated mice after re-infarction demonstrated a significant decline in most arrhythmias with reduced inflammatory pathways. Additionally, following stem-cell therapy we found numerous highly expressed genes to be either linked to lowering the risk of heart failure, cardiomyopathy or sudden cardiac death. Moreover, genes known to be associated with arrhythmogenesis and key mutations underlying arrhythmias were downregulated. In summary, our stem-cell therapy led to a reduction in cardiac arrhythmias after MI and showed a downregulation of already established inflammatory pathways. Furthermore, our study reveals gene regulation pathways that have a potentially direct influence on arrhythmogenesis after myocardial infarction.
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Affiliation(s)
- Beschan Ahmad
- Department of Cardiac Surgery, Rostock University Medical Center, 18057 Rostock, Germany
- Department of Life, Light & Matter, Interdisciplinary Faculty, Rostock University, 18059 Rostock, Germany
| | - Anna Skorska
- Department of Cardiac Surgery, Rostock University Medical Center, 18057 Rostock, Germany
- Department of Life, Light & Matter, Interdisciplinary Faculty, Rostock University, 18059 Rostock, Germany
| | - Markus Wolfien
- Department of Systems Biology and Bioinformatics, University of Rostock, 18051 Rostock, Germany
- Institute for Medical Informatics and Biometry, Faculty of Medicine Carl Gustav Carus, Technical University Dresden, 01307 Dresden, Germany
| | - Haval Sadraddin
- Department of Cardiac Surgery, Rostock University Medical Center, 18057 Rostock, Germany
- Department of Life, Light & Matter, Interdisciplinary Faculty, Rostock University, 18059 Rostock, Germany
| | - Heiko Lemcke
- Department of Cardiac Surgery, Rostock University Medical Center, 18057 Rostock, Germany
- Department of Life, Light & Matter, Interdisciplinary Faculty, Rostock University, 18059 Rostock, Germany
| | - Praveen Vasudevan
- Department of Cardiac Surgery, Rostock University Medical Center, 18057 Rostock, Germany
- Department of Life, Light & Matter, Interdisciplinary Faculty, Rostock University, 18059 Rostock, Germany
| | - Olaf Wolkenhauer
- Department of Systems Biology and Bioinformatics, University of Rostock, 18051 Rostock, Germany
| | - Gustav Steinhoff
- Department of Cardiac Surgery, Rostock University Medical Center, 18057 Rostock, Germany
- Department of Life, Light & Matter, Interdisciplinary Faculty, Rostock University, 18059 Rostock, Germany
| | - Robert David
- Department of Cardiac Surgery, Rostock University Medical Center, 18057 Rostock, Germany
- Department of Life, Light & Matter, Interdisciplinary Faculty, Rostock University, 18059 Rostock, Germany
- Correspondence: ; Tel.: +49-381-4988973; Fax: +49-381-4988970
| | - Ralf Gaebel
- Department of Cardiac Surgery, Rostock University Medical Center, 18057 Rostock, Germany
- Department of Life, Light & Matter, Interdisciplinary Faculty, Rostock University, 18059 Rostock, Germany
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12
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Asare IK, Galende AP, Garcia AB, Cruz MF, Moura ACM, Campbell CC, Scheyer M, Alao JP, Alston S, Kravats AN, Sanders CR, Lorigan GA, Sahu ID. Investigating Structural Dynamics of KCNE3 in Different Membrane Environments Using Molecular Dynamics Simulations. MEMBRANES 2022; 12:membranes12050469. [PMID: 35629795 PMCID: PMC9147993 DOI: 10.3390/membranes12050469] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Revised: 03/21/2022] [Accepted: 04/21/2022] [Indexed: 11/27/2022]
Abstract
KCNE3 is a potassium channel accessory transmembrane protein that regulates the function of various voltage-gated potassium channels such as KCNQ1. KCNE3 plays an important role in the recycling of potassium ion by binding with KCNQ1. KCNE3 can be found in the small intestine, colon, and in the human heart. Despite its biological significance, there is little information on the structural dynamics of KCNE3 in native-like membrane environments. Molecular dynamics (MD) simulations are a widely used as a tool to study the conformational dynamics and interactions of proteins with lipid membranes. In this study, we have utilized all-atom molecular dynamics simulations to characterize the molecular motions and the interactions of KCNE3 in a bilayer composed of: a mixture of POPC and POPG lipids (3:1), POPC alone, and DMPC alone. Our MD simulation results suggested that the transmembrane domain (TMD) of KCNE3 is less flexible and more stable when compared to the N- and C-termini of KCNE3 in all three membrane environments. The conformational flexibility of N- and C-termini varies across these three lipid environments. The MD simulation results further suggested that the TMD of KCNE3 spans the membrane width, having residue A69 close to the center of the lipid bilayers and residues S57 and S82 close to the lipid bilayer membrane surfaces. These results are consistent with previous biophysical studies of KCNE3. The outcomes of these MD simulations will help design biophysical experiments and complement the experimental data obtained on KCNE3 to obtain a more detailed understanding of its structural dynamics in the native membrane environment.
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Affiliation(s)
- Isaac K. Asare
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA; (I.K.A.); (A.P.G.); (A.B.G.); (M.F.C.); (A.C.M.M.); (C.C.C.); (M.S.); (S.A.)
| | - Alberto Perez Galende
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA; (I.K.A.); (A.P.G.); (A.B.G.); (M.F.C.); (A.C.M.M.); (C.C.C.); (M.S.); (S.A.)
| | - Andres Bastidas Garcia
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA; (I.K.A.); (A.P.G.); (A.B.G.); (M.F.C.); (A.C.M.M.); (C.C.C.); (M.S.); (S.A.)
| | - Mateo Fernandez Cruz
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA; (I.K.A.); (A.P.G.); (A.B.G.); (M.F.C.); (A.C.M.M.); (C.C.C.); (M.S.); (S.A.)
| | - Anna Clara Miranda Moura
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA; (I.K.A.); (A.P.G.); (A.B.G.); (M.F.C.); (A.C.M.M.); (C.C.C.); (M.S.); (S.A.)
| | - Conner C. Campbell
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA; (I.K.A.); (A.P.G.); (A.B.G.); (M.F.C.); (A.C.M.M.); (C.C.C.); (M.S.); (S.A.)
| | - Matthew Scheyer
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA; (I.K.A.); (A.P.G.); (A.B.G.); (M.F.C.); (A.C.M.M.); (C.C.C.); (M.S.); (S.A.)
| | - John Paul Alao
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA; (J.P.A.); (A.N.K.)
| | - Steve Alston
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA; (I.K.A.); (A.P.G.); (A.B.G.); (M.F.C.); (A.C.M.M.); (C.C.C.); (M.S.); (S.A.)
| | - Andrea N. Kravats
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA; (J.P.A.); (A.N.K.)
| | - Charles R. Sanders
- Center for Structural Biology, Department of Biochemistry, Vanderbilt University, Nashville, TN 37232, USA;
| | - Gary A. Lorigan
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA; (J.P.A.); (A.N.K.)
- Correspondence: (G.A.L.); (I.D.S.); Tel.: +1-(513)-529-2813 (G.A.L.); +1-(270)-789-5597 (I.D.S.)
| | - Indra D. Sahu
- Natural Science Division, Campbellsville University, Campbellsville, KY 42718, USA; (I.K.A.); (A.P.G.); (A.B.G.); (M.F.C.); (A.C.M.M.); (C.C.C.); (M.S.); (S.A.)
- Department of Chemistry and Biochemistry, Miami University, Oxford, OH 45056, USA; (J.P.A.); (A.N.K.)
- Correspondence: (G.A.L.); (I.D.S.); Tel.: +1-(513)-529-2813 (G.A.L.); +1-(270)-789-5597 (I.D.S.)
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13
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Yan Q. The Yin-Yang Dynamics in Cardiovascular Pharmacogenomics and Personalized Medicine. Methods Mol Biol 2022; 2547:255-266. [PMID: 36068468 DOI: 10.1007/978-1-0716-2573-6_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Studies of genetic variants and systems biology have indicated that Yin-Yang dynamics are especially meaningful for cardiovascular pharmacogenomics and personalized therapeutic strategies. The comprehensive concepts of Yin-Yang can be used to characterize the dynamical factors in the adaptive microenvironments of the complex cardiovascular systems. The Yin-Yang imbalances in the complex adaptive systems (CAS) at different levels and stages are essential for cardiovascular diseases (CVDs), including atherosclerosis, hypertension, and heart failure (HF). At the molecular and cellular levels, Yin-Yang interconnections have been considered critical for genetic variants and various pathways, mitophagy, cell death, and cholesterol homeostasis. The significance of the adaptive and spatiotemporal factors in the nonlinear Yin-Yang interactions has been identified in different pathophysiological processes such as fibrosis. The Yin-Yang dynamical balances between proinflammatory and anti-inflammatory cytokines have vital roles in the complex reactions to stress and impairments to the heart. Procoagulant and anticoagulant lipids and lipoproteins in plasma have the Yin-Yang roles that increase or decrease thrombin productions and thrombosis. At the systems level, the Yin-Yang type of relationships has been suggested between atrial fibrillation (AF), diastolic dysfunction (DD), and HF. Based on such perceptions, systemic and personalized cardiovascular profiles can be constructed by embracing the features of CAS, especially the microenvironments and the adaptative pathophysiological stages. These features can be integrated into the comprehensive Yin-Yang dynamics framework to identify more accurate biomarkers for better prevention and treatments. The goal of reestablishing ubiquitous Yin-Yang dynamical balances may become the central theme for personalized and systems medicine for cardiovascular diseases.
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14
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Sen S, Hallee L, Lam CK. The Potential of Gamma Secretase as a Therapeutic Target for Cardiac Diseases. J Pers Med 2021; 11:jpm11121294. [PMID: 34945766 PMCID: PMC8703931 DOI: 10.3390/jpm11121294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2021] [Revised: 11/24/2021] [Accepted: 12/01/2021] [Indexed: 11/16/2022] Open
Abstract
Heart diseases are some of the most common and pressing threats to human health worldwide. The American Heart Association and the National Institute of Health jointly work to annually update data on cardiac diseases. In 2018, 126.9 million Americans were reported as having some form of cardiac disorder, with an estimated direct and indirect total cost of USD 363.4 billion. This necessitates developing therapeutic interventions for heart diseases to improve human life expectancy and economic relief. In this review, we look into gamma-secretase as a potential therapeutic target for cardiac diseases. Gamma-secretase, an aspartyl protease enzyme, is responsible for the cleavage and activation of a number of substrates that are relevant to normal cardiac development and function as found in mutation studies. Some of these substrates are involved in downstream signaling processes and crosstalk with pathways relevant to heart diseases. Most of the substrates and signaling events we explored were found to be potentially beneficial to maintain cardiac function in diseased conditions. This review presents an updated overview of the current knowledge on gamma-secretase processing of cardiac-relevant substrates and seeks to understand if the modulation of gamma-secretase activity would be beneficial to combat cardiac diseases.
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Affiliation(s)
- Sujoita Sen
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA;
| | - Logan Hallee
- Department of Mathematical Sciences, University of Delaware, Newark, DE 19716, USA;
| | - Chi Keung Lam
- Department of Biological Sciences, University of Delaware, Newark, DE 19716, USA;
- Correspondence: ; Tel.: +1-302-831-3165
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15
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Montell C. Drosophila sensory receptors-a set of molecular Swiss Army Knives. Genetics 2021; 217:1-34. [PMID: 33683373 DOI: 10.1093/genetics/iyaa011] [Citation(s) in RCA: 46] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 11/17/2020] [Indexed: 01/01/2023] Open
Abstract
Genetic approaches in the fruit fly, Drosophila melanogaster, have led to a major triumph in the field of sensory biology-the discovery of multiple large families of sensory receptors and channels. Some of these families, such as transient receptor potential channels, are conserved from animals ranging from worms to humans, while others, such as "gustatory receptors," "olfactory receptors," and "ionotropic receptors," are restricted to invertebrates. Prior to the identification of sensory receptors in flies, it was widely assumed that these proteins function in just one modality such as vision, smell, taste, hearing, and somatosensation, which includes thermosensation, light, and noxious mechanical touch. By employing a vast combination of genetic, behavioral, electrophysiological, and other approaches in flies, a major concept to emerge is that many sensory receptors are multitaskers. The earliest example of this idea was the discovery that individual transient receptor potential channels function in multiple senses. It is now clear that multitasking is exhibited by other large receptor families including gustatory receptors, ionotropic receptors, epithelial Na+ channels (also referred to as Pickpockets), and even opsins, which were formerly thought to function exclusively as light sensors. Genetic characterizations of these Drosophila receptors and the neurons that express them also reveal the mechanisms through which flies can accurately differentiate between different stimuli even when they activate the same receptor, as well as mechanisms of adaptation, amplification, and sensory integration. The insights gleaned from studies in flies have been highly influential in directing investigations in many other animal models.
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Affiliation(s)
- Craig Montell
- Department of Molecular, Cellular, and Developmental Biology, The Neuroscience Research Institute, University of California, Santa Barbara, CA 93106, USA
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16
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Control of Biophysical and Pharmacological Properties of Potassium Channels by Ancillary Subunits. Handb Exp Pharmacol 2021; 267:445-480. [PMID: 34247280 DOI: 10.1007/164_2021_512] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Potassium channels facilitate and regulate physiological processes as diverse as electrical signaling, ion, solute and hormone secretion, fluid homeostasis, hearing, pain sensation, muscular contraction, and the heartbeat. Potassium channels are each formed by either a tetramer or dimer of pore-forming α subunits that co-assemble to create a multimer with a K+-selective pore that in most cases is capable of functioning as a discrete unit to pass K+ ions across the cell membrane. The reality in vivo, however, is that the potassium channel α subunit multimers co-assemble with ancillary subunits to serve specific physiological functions. The ancillary subunits impart specific physiological properties that are often required for a particular activity in vivo; in addition, ancillary subunit interaction often alters the pharmacology of the resultant complex. In this chapter the modes of action of ancillary subunits on K+ channel physiology and pharmacology are described and categorized into various mechanistic classes.
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17
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Cabrera‐Garcia D, Bekdash R, Abbott GW, Yazawa M, Harrison NL. The envelope protein of SARS-CoV-2 increases intra-Golgi pH and forms a cation channel that is regulated by pH. J Physiol 2021; 599:2851-2868. [PMID: 33709461 PMCID: PMC8251088 DOI: 10.1113/jp281037] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 03/02/2021] [Indexed: 12/19/2022] Open
Abstract
KEY POINTS We report a novel method for the transient expression of SARS-CoV-2 envelope (E) protein in intracellular organelles and the plasma membrane of mammalian cells and Xenopus oocytes. Intracellular expression of SARS-CoV-2 E protein increases intra-Golgi pH. By targeting the SARS-CoV-2 E protein to the plasma membrane, we show that it forms a cation channel, viroporin, that is modulated by changes of pH. This method for studying the activity of viroporins may facilitate screening for new antiviral drugs to identify novel treatments for COVID-19. ABSTRACT The envelope (E) protein of coronaviruses such as SARS-CoV-1 is proposed to form an ion channel or viroporin that participates in viral propagation and pathogenesis. Here we developed a technique to study the E protein of SARS-CoV-2 in mammalian cells by directed targeting using a carboxyl-terminal fluorescent protein tag, mKate2. The wild-type SARS-CoV-2 E protein can be trafficked to intracellular organelles, notably the endoplasmic reticulum-Golgi intermediate complex, where its expression increases pH inside the organelle. We also succeeded in targeting SARS-CoV-2 E to the plasma membrane, which enabled biophysical analysis using whole-cell patch clamp recording in a mammalian cell line, HEK 293 cells, and two-electrode voltage clamp electrophysiology in Xenopus oocytes. The results suggest that the E protein forms an ion channel that is permeable to monovalent cations such as Na+ , Cs+ and K+ . The E current is nearly time- and voltage-independent when E protein is expressed in mammalian cells, and is modulated by changes of pH. At pH 6.0 and 7.4, the E protein current is activated, whereas at pH 8.0 and 9.0, the amplitude of E protein current is reduced, and in oocytes the inward E current fades at pH 9 in a time- and voltage-dependent manner. Using this directed targeting method and electrophysiological recordings, potential inhibitors of the E protein can be screened and subsequently investigated for antiviral activity against SARS-CoV-2 in vitro and possible efficacy in treating COVID-19.
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Affiliation(s)
| | - Ramsey Bekdash
- Department of Molecular Pharmacology and TherapeuticsColumbia UniversityNew YorkNYUSA
- Columbia Stem Cell Initiative, Department of Rehabilitation and Regenerative MedicineColumbia UniversityNew YorkNYUSA
| | - Geoffrey W. Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of MedicineUniversity of CaliforniaIrvineCAUSA
| | - Masayuki Yazawa
- Department of Molecular Pharmacology and TherapeuticsColumbia UniversityNew YorkNYUSA
- Columbia Stem Cell Initiative, Department of Rehabilitation and Regenerative MedicineColumbia UniversityNew YorkNYUSA
| | - Neil L. Harrison
- Department of AnesthesiologyColumbia UniversityNew YorkNYUSA
- Department of Molecular Pharmacology and TherapeuticsColumbia UniversityNew YorkNYUSA
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18
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Fluorescence Fluctuation Spectroscopy enables quantification of potassium channel subunit dynamics and stoichiometry. Sci Rep 2021; 11:10719. [PMID: 34021177 PMCID: PMC8140153 DOI: 10.1038/s41598-021-90002-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 04/15/2021] [Indexed: 11/08/2022] Open
Abstract
Voltage-gated potassium (Kv) channels are a family of membrane proteins that facilitate K+ ion diffusion across the plasma membrane, regulating both resting and action potentials. Kv channels comprise four pore-forming α subunits, each with a voltage sensing domain, and they are regulated by interaction with β subunits such as those belonging to the KCNE family. Here we conducted a comprehensive biophysical characterization of stoichiometry and protein diffusion across the plasma membrane of the epithelial KCNQ1-KCNE2 complex, combining total internal reflection fluorescence (TIRF) microscopy and a series of complementary Fluorescence Fluctuation Spectroscopy (FFS) techniques. Using this approach, we found that KCNQ1-KCNE2 has a predominant 4:4 stoichiometry, while non-bound KCNE2 subunits are mostly present as dimers in the plasma membrane. At the same time, we identified unique spatio-temporal diffusion modalities and nano-environment organization for each channel subunit. These findings improve our understanding of KCNQ1-KCNE2 channel function and suggest strategies for elucidating the subunit stoichiometry and forces directing localization and diffusion of ion channel complexes in general.
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19
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Huang H, Chamness LM, Vanoye CG, Kuenze G, Meiler J, George AL, Schlebach JP, Sanders CR. Disease-linked supertrafficking of a potassium channel. J Biol Chem 2021; 296:100423. [PMID: 33600800 PMCID: PMC7988323 DOI: 10.1016/j.jbc.2021.100423] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 02/04/2021] [Accepted: 02/12/2021] [Indexed: 12/21/2022] Open
Abstract
Gain-of-function (GOF) mutations in the voltage-gated potassium channel subfamily Q member 1 (KCNQ1) can induce cardiac arrhythmia. In this study, it was tested whether any of the known human GOF disease mutations in KCNQ1 act by increasing the amount of KCNQ1 that reaches the cell surface-"supertrafficking." Seven of the 15 GOF mutants tested were seen to surface traffic more efficiently than the WT channel. Among these, we found that the levels of R231C KCNQ1 in the plasma membrane were fivefold higher than the WT channel. This was shown to arise from the combined effects of enhanced efficiency of translocon-mediated membrane integration of the S4 voltage-sensor helix and from enhanced post-translational folding/trafficking related to the energetic linkage of C231 with the V129 and F166 side chains. Whole-cell electrophysiology recordings confirmed that R231C KCNQ1 in complex with the voltage-gated potassium channel-regulatory subfamily E member 1 not only exhibited constitutive conductance but also revealed that the single-channel activity of this mutant is only 20% that of WT. The GOF phenotype associated with R231C therefore reflects the effects of supertrafficking and constitutive channel activation, which together offset reduced channel activity. These investigations show that membrane protein supertrafficking can contribute to human disease.
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Affiliation(s)
- Hui Huang
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA; Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA
| | - Laura M Chamness
- Department of Chemistry, Indiana University, Bloomington, Indiana, USA
| | - Carlos G Vanoye
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | - Georg Kuenze
- Departments of Chemistry and Pharmacology, Vanderbilt University, Nashville, Tennessee, USA; Department of Bioinformatics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Jens Meiler
- Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA; Departments of Chemistry and Pharmacology, Vanderbilt University, Nashville, Tennessee, USA; Department of Bioinformatics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Alfred L George
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA
| | | | - Charles R Sanders
- Department of Biochemistry, Vanderbilt University, Nashville, Tennessee, USA; Center for Structural Biology, Vanderbilt University, Nashville, Tennessee, USA; Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA.
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20
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Mehboob R, Kurdi M, Ahmad M, Gilani SA, Khalid S, Nasief H, Mirdad A, Malibary H, Hakamy S, Hassan A, Alaifan M, Bamaga A, Shahzad SA. Comprehensive Analysis of Genes Associated With Sudden Infant Death Syndrome. Front Pediatr 2021; 9:742225. [PMID: 34722422 PMCID: PMC8555024 DOI: 10.3389/fped.2021.742225] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 09/13/2021] [Indexed: 12/15/2022] Open
Abstract
Background: Sudden infant death syndrome (SIDS) is a tragic incident which remains a mystery even after post-mortem investigation and thorough researches. Methods: This comprehensive review is based on the genes reported in the molecular autopsy studies conducted on SIDS so far. A total of 20 original studies and 7 case reports were identified and included in this analysis. The genes identified in children or adults were not included. Most of the genes reported in these studies belonged to cardiac channel and cardiomyopathy. Cardiac channel genes in SIDS were scrutinized for further analysis. Results: After screening and removing the duplicates, 42 unique genes were extracted. When the location of these genes was assessed, it was observed that most of these belonged to Chromosomes 11, 1 and 3 in sequential manner. The pathway analysis shows that these genes are involved in the regulation of heart rate, action potential, cardiac muscle cell contraction and heart contraction. The protein-protein interaction network was also very big and highly interactive. SCN5A, CAV3, ALG10B, AKAP9 and many more were mainly found in these cases and were regulated by many transcription factors such as MYOG C2C1 and CBX3 HCT11. Micro RNA, "hsa-miR-133a-3p" was found to be prevalent in the targeted genes. Conclusions: Molecular and computational approaches are a step forward toward exploration of these sad demises. It is so far a new arena but seems promising to dig out the genetic cause of SIDS in the years to come.
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Affiliation(s)
- Riffat Mehboob
- Research Unit, Faculty of Allied Health Sciences, The University of Lahore, Lahore, Pakistan.,Lahore Medical Research Center, LLP, Lahore, Pakistan
| | - Maher Kurdi
- Department of Pathology, Faculty of Medicine in Rabigh, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Mursleen Ahmad
- Department of Medicine, Sahiwal Medical College, Sahiwal, Pakistan
| | - Syed Amir Gilani
- Research Unit, Faculty of Allied Health Sciences, The University of Lahore, Lahore, Pakistan
| | - Sidra Khalid
- Lahore Medical Research Center, LLP, Lahore, Pakistan
| | - Hisham Nasief
- Department of Obstetric and Gynecology, Faculty of Medicine, King Abdulaziz University and Hospital, Jeddah, Saudi Arabia
| | - Abeer Mirdad
- Pediatric Department, East Jeddah Hospital, Jeddah, Saudi Arabia
| | - Husam Malibary
- Department of Internal Medicine, Faculty of Medicine, King Abdul Aziz University, Jeddah, Saudi Arabia
| | - Sahar Hakamy
- Center of Excellence in Genomic Research, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Amber Hassan
- Research Unit, Faculty of Allied Health Sciences, The University of Lahore, Lahore, Pakistan
| | - Meshari Alaifan
- Department of Paediatrics, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Ahmed Bamaga
- Paediatric Department, King Faisal Specialist Hospital and Research Center, Jeddah, Saudi Arabia.,Neurology and Pediatric Department, Faculty of Medicine, King Abdulaziz University Hospital, King Abdulaziz University, Jeddah, Saudi Arabia
| | - Syed Adnan Shahzad
- Faculty of Medicine and University Hospital of Cologne, Institute of Virology, University of Cologne, Cologne, Germany
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21
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Abancens M, Bustos V, Harvey H, McBryan J, Harvey BJ. Sexual Dimorphism in Colon Cancer. Front Oncol 2020; 10:607909. [PMID: 33363037 PMCID: PMC7759153 DOI: 10.3389/fonc.2020.607909] [Citation(s) in RCA: 83] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 11/09/2020] [Indexed: 12/12/2022] Open
Abstract
A higher incidence of colorectal cancer (CRC) is found in males compared to females. Young women (18-44 years) with CRC have a better survival outcome compared to men of the same age or compared to older women (over 50 years), indicating a global incidence of sexual dimorphism in CRC rates and survival. This suggests a protective role for the sex steroid hormone estrogen in CRC development. Key proliferative pathways in CRC tumorigenesis exhibit sexual dimorphism, which confer better survival in females through estrogen regulated genes and cell signaling. Estrogen regulates the activity of a class of Kv channels (KCNQ1:KCNE3), which control fundamental ion transport functions of the colon and epithelial mesenchymal transition through bi-directional interactions with the Wnt/β-catenin signalling pathway. Estrogen also modulates CRC proliferative responses in hypoxia via the novel membrane estrogen receptor GPER and HIF1A and VEGF signaling. Here we critically review recent clinical and molecular insights into sexual dimorphism of CRC biology modulated by the tumor microenvironment, estrogen, Wnt/β-catenin signalling, ion channels, and X-linked genes.
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Affiliation(s)
- Maria Abancens
- Department of Molecular Medicine, RCSI University of Medicine and Health Sciences, Beaumont Hospital, Dublin, Ireland
- Department of Surgery, RCSI University of Medicine and Health Sciences, Beaumont Hospital, Dublin, Ireland
| | - Viviana Bustos
- Departamento de Acuicultura y Recursos Agroalimentarios, Programa Fitogen, Universidad de Los Lagos, Osorno, Chile
| | - Harry Harvey
- Department of Medical Oncology, Cork University Hospital, Cork, Ireland
| | - Jean McBryan
- Department of Molecular Medicine, RCSI University of Medicine and Health Sciences, Beaumont Hospital, Dublin, Ireland
- Department of Surgery, RCSI University of Medicine and Health Sciences, Beaumont Hospital, Dublin, Ireland
| | - Brian J. Harvey
- Department of Molecular Medicine, RCSI University of Medicine and Health Sciences, Beaumont Hospital, Dublin, Ireland
- Centro de Estudios Cientificos CECs, Valdivia, Chile
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22
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Fenyves BG, Arnold A, Gharat VG, Haab C, Tishinov K, Peter F, de Quervain D, Papassotiropoulos A, Stetak A. Dual Role of an mps-2/KCNE-Dependent Pathway in Long-Term Memory and Age-Dependent Memory Decline. Curr Biol 2020; 31:527-539.e7. [PMID: 33259792 DOI: 10.1016/j.cub.2020.10.069] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 09/14/2020] [Accepted: 10/21/2020] [Indexed: 01/24/2023]
Abstract
Activity-dependent persistent changes in neuronal intrinsic excitability and synaptic strength are underlying learning and memory. Voltage-gated potassium (Kv) channels are potential regulators of memory and may be linked to age-dependent neuronal disfunction. MinK-related peptides (MiRPs) are conserved transmembrane proteins modulating Kv channels; however, their possible role in the regulation of memory and age-dependent memory decline are unknown. Here, we show that, in C. elegans, mps-2 is the sole member of the MiRP family that controls exclusively long-term associative memory (LTAM) in AVA neuron. In addition, we demonstrate that mps-2 also plays a critical role in age-dependent memory decline. In young adult worms, mps-2 is transcriptionally upregulated by CRH-1/cyclic AMP (cAMP)-response-binding protein (CREB) during LTAM, although the mps-2 baseline expression is CREB independent and instead, during aging, relies on nhr-66, which acts as an age-dependent repressor. Deletion of nhr-66 or its binding element in the mps-2 promoter prevents age-dependent transcriptional repression of mps-2 and memory decline. Finally, MPS-2 acts through the modulation of the Kv2.1/KVS-3 and Kv2.2/KVS-4 heteromeric potassium channels. Altogether, we describe a conserved MPS-2/KVS-3/KVS-4 pathway essential for LTAM and also for a programmed control of physiological age-dependent memory decline.
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Affiliation(s)
- Bank G Fenyves
- Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland; Division of Molecular Neuroscience, Department of Psychology, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland; Department of Molecular Biology, Semmelweis University, Tűzoltó u. 37-47, 1094 Budapest, Hungary
| | - Andreas Arnold
- Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland; Division of Molecular Neuroscience, Department of Psychology, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland
| | - Vaibhav G Gharat
- Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland; Division of Molecular Neuroscience, Department of Psychology, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland
| | - Carmen Haab
- Division of Molecular Neuroscience, Department of Psychology, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland
| | - Kiril Tishinov
- Biozentrum, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland
| | - Fabian Peter
- Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland; Division of Molecular Neuroscience, Department of Psychology, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland
| | - Dominique de Quervain
- Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland; Division of Cognitive Neuroscience, Department of Psychology, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland; University Psychiatric Clinics, University of Basel, Wilhelm Klein-Strasse 27, 4055 Basel, Switzerland
| | - Andreas Papassotiropoulos
- Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland; Division of Molecular Neuroscience, Department of Psychology, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland; Biozentrum, Life Sciences Training Facility, University of Basel, Klingelbergstrasse 50/70, 4056 Basel, Switzerland; University Psychiatric Clinics, University of Basel, Wilhelm Klein-Strasse 27, 4055 Basel, Switzerland
| | - Attila Stetak
- Transfaculty Research Platform Molecular and Cognitive Neurosciences, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland; Division of Molecular Neuroscience, Department of Psychology, University of Basel, Birmannsgasse 8, 4055 Basel, Switzerland; University Psychiatric Clinics, University of Basel, Wilhelm Klein-Strasse 27, 4055 Basel, Switzerland.
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Fantin SM, Huang H, Sanders CR, Ruotolo BT. Collision-Induced Unfolding Differentiates Functional Variants of the KCNQ1 Voltage Sensor Domain. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2020; 31:2348-2355. [PMID: 32960579 PMCID: PMC8106873 DOI: 10.1021/jasms.0c00288] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
The KCNQ1 voltage-gated potassium channel regulates the repolarization of cardiac cells, and a plurality of point mutations in its voltage-sensing domain (VSD) are associated with toxic gain or loss of pore function, resulting in disease. As is the case with many disease-associated membrane proteins, there are hundreds of human variants of interest identified for KCNQ1; however, a significant portion of these variants have not been characterized in relation to their functional and disease associations. Additionally, as the VSD consists of four transmembrane helices, studies into dynamic structural differences among KCNQ1 VSD variants are hindered by the current limitations and deficits in the high-resolution structure determination of membrane proteins. Here, we use native ion mobility-mass spectrometry and collision-induced unfolding (CIU) to address the need for a high throughput-compatible method for the structural characterization of membrane protein variants of unknown significance using the KCNQ1 VSD as a model system. We perform CIU on wild-type and three mutant KCNQ1 VSD forms associated with the toxic gain or loss of function and show through both automated feature detection and comprehensive difference analysis of the CIU data sets that the variants are clearly grouped by function and disease association. We also construct a classification scheme based on the CIU data sets, which is able to differentiate the variant functional groups and classify a recently characterized variant to its correct grouping. Further, we probe the stability of the KCNQ1 VSD variants when liberated from C12E8 micelles at pH 8.0 and find preliminary evidence that the R231C mutation associated with the gain of the pore function is destabilized relative to the wild-type and loss of function variants.
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Affiliation(s)
- Sarah M. Fantin
- University of Michigan Department of Chemistry, Ann Arbor, Michigan 48109, United States
| | - Hui Huang
- Vanderbilt University, Department of Biochemistry, Nashville, Tennessee 37232, United States
| | - Charles R. Sanders
- Vanderbilt University, Department of Biochemistry, Nashville, Tennessee 37232, United States
| | - Brandon T. Ruotolo
- University of Michigan Department of Chemistry, Ann Arbor, Michigan 48109, United States
- Corresponding Author:
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24
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Hu B, Zeng WP, Li X, Al-Sheikh U, Chen SY, Ding J. A conserved arginine/lysine-based motif promotes ER export of KCNE1 and KCNE2 to regulate KCNQ1 channel activity. Channels (Austin) 2020; 13:483-497. [PMID: 31679457 PMCID: PMC6833972 DOI: 10.1080/19336950.2019.1685626] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
KCNE β-subunits play critical roles in modulating cardiac voltage-gated potassium channels. Among them, KCNE1 associates with KCNQ1 channel to confer a slow-activated IKs current, while KCNE2 functions as a dominant negative modulator to suppress the current amplitude of KCNQ1. Any anomaly in these channels will lead to serious myocardial diseases, such as the long QT syndrome (LQTS). Trafficking defects of KCNE1 have been reported to account for the pathogenesis of LQT5. However, the molecular mechanisms underlying KCNE forward trafficking remain elusive. Here, we describe an arginine/lysine-based motif ([R/K](S)[R/K][R/K]) in the proximal C-terminus regulating the endoplasmic reticulum (ER) export of KCNE1 and KCNE2 in HEK293 cells. Notably, this motif is highly conserved in the KCNE family. Our results indicate that the forward trafficking of KCNE2 controlled by the motif (KSKR) is essential for suppressing the cell surface expression and current amplitude of KCNQ1. Unlike KCNE2, the motif (RSKK) in KCNE1 plays important roles in modulating the gating of KCNQ1 in addition to mediating the ER export of KCNE1. Furthermore, truncations of the C-terminus did not reduce the apparent affinity of KCNE2 for KCNQ1, demonstrating that the rigid C-terminus of KCNE2 may not physically interact with KCNQ1. In contrast, the KCNE1 C-terminus is critical for its interaction with KCNQ1. These results contribute to the understanding of the mechanisms of KCNE1 and KCNE2 membrane targeting and how they coassemble with KCNQ1 to regulate the channels activity.
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Affiliation(s)
- Bin Hu
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Wen-Ping Zeng
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China.,School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China
| | - Xia Li
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - Umar Al-Sheikh
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China
| | - San-You Chen
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China.,CAS Key Laboratory of Microscale Magnetic Resonance and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui, China
| | - Jiuping Ding
- Key Laboratory of Molecular Biophysics of the Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei, China
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25
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Abbott GW. KCNQs: Ligand- and Voltage-Gated Potassium Channels. Front Physiol 2020; 11:583. [PMID: 32655402 PMCID: PMC7324551 DOI: 10.3389/fphys.2020.00583] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 05/11/2020] [Indexed: 12/26/2022] Open
Abstract
Voltage-gated potassium (Kv) channels in the KCNQ (Kv7) family are essential features of a broad range of excitable and non-excitable cell types and are found in organisms ranging from Hydra vulgaris to Homo sapiens. Although they are firmly in the superfamily of S4 domain-bearing voltage-sensing ion channels, KCNQ channels are highly sensitive to a range of endogenous and exogenous small molecules that act directly on the pore, the voltage-sensing domain, or the interface between the two. The focus of this review is regulation of KCNQs by direct binding of neurotransmitters and metabolites from both animals and plants and the role of the latter in the effects of plants consumed for food and as traditional folk medicines. The conceptual question arises: Are KCNQs voltage-gated channels that are also sensitive to ligands or ligand-gated channels that are also sensitive to voltage?
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Affiliation(s)
- Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, CA, United States
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26
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A Family of Auxiliary Subunits of the TRP Cation Channel Encoded by the Complex inaF Locus. Genetics 2020; 215:713-728. [PMID: 32434796 DOI: 10.1534/genetics.120.303268] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 05/15/2020] [Indexed: 02/06/2023] Open
Abstract
TRP channels function in many types of sensory receptor cells. Despite extensive analyses, an open question is whether there exists a family of auxiliary subunits, which could influence localization, trafficking, and function of TRP channels. Here, using Drosophila melanogaster, we reveal a previously unknown TRP interacting protein, INAF-C, which is expressed exclusively in the ultraviolet-sensing R7 photoreceptor cells. INAF-C is encoded by an unusual locus comprised of four distinct coding regions, which give rise to four unique single-transmembrane-containing proteins. With the exception of INAF-B, roles for the other INAF proteins were unknown. We found that both INAF-B and INAF-C are required for TRP stability and localization in R7 cells. Conversely, loss of just INAF-B greatly reduced TRP from other types of photoreceptor cells, but not R7. The requirements for TRP and INAF are reciprocal, since loss of TRP decreased the concentrations of both INAF-B and INAF-C. INAF-A, which is not normally expressed in photoreceptor cells, can functionally substitute for INAF-B, indicating that it is a third TRP auxiliary protein. Reminiscent of the structural requirements between Kv channels and KCNE auxiliary subunits, the codependencies of TRP and INAF depended on several transmembrane domains (TMDs) in TRP, and the TMD and the C-terminus of INAF-B. Our studies support a model in which the inaF locus encodes a family of at least three TRP auxiliary subunits.
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27
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Di Lollo V, Canciello A, Orsini M, Bernabò N, Ancora M, Di Federico M, Curini V, Mattioli M, Russo V, Mauro A, Cammà C, Barboni B. Transcriptomic and computational analysis identified LPA metabolism, KLHL14 and KCNE3 as novel regulators of Epithelial-Mesenchymal Transition. Sci Rep 2020; 10:4180. [PMID: 32144311 PMCID: PMC7060278 DOI: 10.1038/s41598-020-61017-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 02/17/2020] [Indexed: 12/15/2022] Open
Abstract
Epithelial-mesenchymal transition (EMT) is a complex biological program between physiology and pathology. Here, amniotic epithelial cells (AEC) were used as in vitro model of transiently inducible EMT in order to evaluate the transcriptional insights underlying this process. Therefore, RNA-seq was used to identify the differentially expressed genes and enrichment analyses were carried out to assess the intracellular pathways involved. As a result, molecules exclusively expressed in AEC that experienced EMT (GSTA1-1 and GSTM3) or when this process is inhibited (KLHL14 and KCNE3) were identified. Lastly, the network theory was used to obtain a computational model able to recognize putative controller genes involved in the induction and in the prevention of EMT. The results suggested an opposite role of lysophosphatidic acid (LPA) synthesis and degradation enzymes in the regulation of EMT process. In conclusion, these molecules may represent novel EMT regulators and also targets for developing new therapeutic strategies.
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Affiliation(s)
- V Di Lollo
- Faculty of Bioscience and Technology for Food, Agriculture and Environment, University of Teramo, Teramo, Italy. .,Molecular biology and genomic Unit, Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise "G. Caporale", Teramo, Italy.
| | - A Canciello
- Faculty of Bioscience and Technology for Food, Agriculture and Environment, University of Teramo, Teramo, Italy.
| | - M Orsini
- Molecular biology and genomic Unit, Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise "G. Caporale", Teramo, Italy
| | - N Bernabò
- Faculty of Bioscience and Technology for Food, Agriculture and Environment, University of Teramo, Teramo, Italy
| | - M Ancora
- Molecular biology and genomic Unit, Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise "G. Caporale", Teramo, Italy
| | - M Di Federico
- Molecular biology and genomic Unit, Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise "G. Caporale", Teramo, Italy
| | - V Curini
- Molecular biology and genomic Unit, Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise "G. Caporale", Teramo, Italy
| | - M Mattioli
- Faculty of Bioscience and Technology for Food, Agriculture and Environment, University of Teramo, Teramo, Italy
| | - V Russo
- Faculty of Bioscience and Technology for Food, Agriculture and Environment, University of Teramo, Teramo, Italy
| | - A Mauro
- Faculty of Bioscience and Technology for Food, Agriculture and Environment, University of Teramo, Teramo, Italy
| | - C Cammà
- Molecular biology and genomic Unit, Istituto Zooprofilattico Sperimentale dell'Abruzzo e del Molise "G. Caporale", Teramo, Italy
| | - B Barboni
- Faculty of Bioscience and Technology for Food, Agriculture and Environment, University of Teramo, Teramo, Italy
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28
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Taylor KC, Kang PW, Hou P, Yang ND, Kuenze G, Smith JA, Shi J, Huang H, White KM, Peng D, George AL, Meiler J, McFeeters RL, Cui J, Sanders CR. Structure and physiological function of the human KCNQ1 channel voltage sensor intermediate state. eLife 2020; 9:e53901. [PMID: 32096762 PMCID: PMC7069725 DOI: 10.7554/elife.53901] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Accepted: 02/24/2020] [Indexed: 12/14/2022] Open
Abstract
Voltage-gated ion channels feature voltage sensor domains (VSDs) that exist in three distinct conformations during activation: resting, intermediate, and activated. Experimental determination of the structure of a potassium channel VSD in the intermediate state has previously proven elusive. Here, we report and validate the experimental three-dimensional structure of the human KCNQ1 voltage-gated potassium channel VSD in the intermediate state. We also used mutagenesis and electrophysiology in Xenopus laevisoocytes to functionally map the determinants of S4 helix motion during voltage-dependent transition from the intermediate to the activated state. Finally, the physiological relevance of the intermediate state KCNQ1 conductance is demonstrated using voltage-clamp fluorometry. This work illuminates the structure of the VSD intermediate state and demonstrates that intermediate state conductivity contributes to the unusual versatility of KCNQ1, which can function either as the slow delayed rectifier current (IKs) of the cardiac action potential or as a constitutively active epithelial leak current.
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Affiliation(s)
- Keenan C Taylor
- Department of Biochemistry, Vanderbilt UniversityNashvilleUnited States
- Center for Structural Biology, Vanderbilt UniversityNashvilleUnited States
| | - Po Wei Kang
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity, and Arrhythmia Center, Washington University in St. LouisSt. LouisUnited States
| | - Panpan Hou
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity, and Arrhythmia Center, Washington University in St. LouisSt. LouisUnited States
| | - Nien-Du Yang
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity, and Arrhythmia Center, Washington University in St. LouisSt. LouisUnited States
| | - Georg Kuenze
- Center for Structural Biology, Vanderbilt UniversityNashvilleUnited States
- Departments of Chemistry and Pharmacology, Vanderbilt UniversityNashvilleUnited States
| | - Jarrod A Smith
- Department of Biochemistry, Vanderbilt UniversityNashvilleUnited States
- Center for Structural Biology, Vanderbilt UniversityNashvilleUnited States
| | - Jingyi Shi
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity, and Arrhythmia Center, Washington University in St. LouisSt. LouisUnited States
| | - Hui Huang
- Department of Biochemistry, Vanderbilt UniversityNashvilleUnited States
- Center for Structural Biology, Vanderbilt UniversityNashvilleUnited States
| | - Kelli McFarland White
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity, and Arrhythmia Center, Washington University in St. LouisSt. LouisUnited States
| | - Dungeng Peng
- Department of Biochemistry, Vanderbilt UniversityNashvilleUnited States
- Center for Structural Biology, Vanderbilt UniversityNashvilleUnited States
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical CenterNashvilleUnited States
| | - Alfred L George
- Department of Pharmacology, Northwestern University Feinberg School of MedicineChicagoUnited States
| | - Jens Meiler
- Center for Structural Biology, Vanderbilt UniversityNashvilleUnited States
- Departments of Chemistry and Pharmacology, Vanderbilt UniversityNashvilleUnited States
- Department of Bioinformatics, Vanderbilt University Medical CenterNashvilleUnited States
| | - Robert L McFeeters
- Department of Chemistry, University of Alabama in HuntsvilleHuntsvilleUnited States
| | - Jianmin Cui
- Department of Biomedical Engineering, Center for the Investigation of Membrane Excitability Disorders, and Cardiac Bioelectricity, and Arrhythmia Center, Washington University in St. LouisSt. LouisUnited States
| | - Charles R Sanders
- Department of Biochemistry, Vanderbilt UniversityNashvilleUnited States
- Center for Structural Biology, Vanderbilt UniversityNashvilleUnited States
- Department of Medicine, Vanderbilt University Medical CenterNashvilleUnited States
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29
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The membrane protein KCNQ1 potassium ion channel: Functional diversity and current structural insights. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1862:183148. [PMID: 31825788 DOI: 10.1016/j.bbamem.2019.183148] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 11/15/2019] [Accepted: 12/04/2019] [Indexed: 12/19/2022]
Abstract
BACKGROUND Ion channels play crucial roles in cellular biology, physiology, and communication including sensory perception. Voltage-gated potassium (Kv) channels execute their function by sensor activation, pore-coupling, and pore opening leading to K+ conductance. SCOPE OF REVIEW This review focuses on a voltage-gated K+ ion channel KCNQ1 (Kv 7.1). Firstly, discussing its positioning in the human ion chanome, and the role of KCNQ1 in the multitude of cellular processes. Next, we discuss the overall channel architecture and current structural insights on KCNQ1. Finally, the gating mechanism involving members of the KCNE family and its interaction with non-KCNE partners. MAJOR CONCLUSIONS KCNQ1 executes its important physiological functions via interacting with KCNE1 and non-KCNE1 proteins/molecules: calmodulin, PIP2, PKA. Although, KCNQ1 has been studied in great detail, several aspects of the channel structure and function still remain unexplored. This review emphasizes the structural and biophysical studies of KCNQ1, its interaction with KCNE1 and non-KCNE1 proteins and focuses on several seminal findings showing the role of VSD and the pore domain in the channel activation and gating properties. GENERAL SIGNIFICANCE KCNQ1 mutations can result in channel defects and lead to several diseases including atrial fibrillation and long QT syndrome. Therefore, a thorough structure-function understanding of this channel complex is essential to understand its role in both normal and disease biology. Moreover, unraveling the molecular mechanisms underlying the regulation of this channel complex will help to find therapeutic strategies for several diseases.
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30
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Deckelbaum RA, Lobov IB, Cheung E, Halasz G, Rajamani S, Lerner J, Tong C, Li Z, Boland P, Dominguez M, Hughes V, Yancopoulos GD, Murphy AJ, Thurston G, Cao J, Romano C, Gale NW. The potassium channel Kcne3 is a VEGFA-inducible gene selectively expressed by vascular endothelial tip cells. Angiogenesis 2019; 23:179-192. [PMID: 31754927 PMCID: PMC7160073 DOI: 10.1007/s10456-019-09696-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 11/02/2019] [Indexed: 12/22/2022]
Abstract
Angiogenesis is largely driven by motile endothelial tip-cells capable of invading avascular tissue domains and enabling new vessel formation. Highly responsive to Vascular Endothelial Growth-Factor-A (VEGFA), endothelial tip-cells also suppress angiogenic sprouting in adjacent stalk cells, and thus have been a primary therapeutic focus in addressing neovascular pathologies. Surprisingly, however, there remains a paucity of specific endothelial tip-cell markers. Here, we employ transcriptional profiling and a lacZ reporter allele to identify Kcne3 as an early and selective endothelial tip-cell marker in multiple angiogenic contexts. In development, Kcne3 expression initiates during early phases of angiogenesis (E9) and remains specific to endothelial tip-cells, often adjacent to regions expressing VEGFA. Consistently, Kcne3 activation is highly responsive to exogenous VEGFA but maintains tip-cell specificity throughout normal retinal angiogenesis. We also demonstrate endothelial tip-cell selectivity of Kcne3 in several injury and tumor models. Together, our data show that Kcne3 is a unique marker of sprouting angiogenic tip-cells and offers new opportunities for investigating and targeting this cell type.
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Affiliation(s)
- Ron A Deckelbaum
- Department of Pre-Therapeutic Target Discovery, Regeneron Pharmaceuticals Inc, Tarrytown, NY, 10591, USA.
| | | | - Eunice Cheung
- Department of Ophthalmology, Regeneron Pharmaceuticals Inc, Tarrytown, NY, 10591, USA
| | - Gabor Halasz
- Department of Bioinformatics, Regeneron Pharmaceuticals Inc, Tarrytown, NY, 10591, USA
| | - Saathyaki Rajamani
- Department of Pre-Therapeutic Target Discovery, Regeneron Pharmaceuticals Inc, Tarrytown, NY, 10591, USA
| | - Julia Lerner
- Department of Pre-Therapeutic Target Discovery, Regeneron Pharmaceuticals Inc, Tarrytown, NY, 10591, USA
| | - Chunxiang Tong
- Department of Pre-Therapeutic Target Discovery, Regeneron Pharmaceuticals Inc, Tarrytown, NY, 10591, USA
| | - Zhe Li
- Department of Oncology & Angiogenesis, Regeneron Pharmaceuticals Inc., Tarrytown, NY, 10591, USA
| | - Patricia Boland
- Department of Oncology & Angiogenesis, Regeneron Pharmaceuticals Inc., Tarrytown, NY, 10591, USA
| | - Melissa Dominguez
- Department of Pre-Therapeutic Target Discovery, Regeneron Pharmaceuticals Inc, Tarrytown, NY, 10591, USA
| | - Virginia Hughes
- Department of Pre-Therapeutic Target Discovery, Regeneron Pharmaceuticals Inc, Tarrytown, NY, 10591, USA
| | - George D Yancopoulos
- Department of Research, Regeneron Pharmaceuticals Inc, Tarrytown, NY, 10591, USA
| | - Andrew J Murphy
- Department of Research, Regeneron Pharmaceuticals Inc, Tarrytown, NY, 10591, USA
| | - Gavin Thurston
- Department of Oncology & Angiogenesis, Regeneron Pharmaceuticals Inc., Tarrytown, NY, 10591, USA
| | - Jingtai Cao
- Department of Ophthalmology, Regeneron Pharmaceuticals Inc, Tarrytown, NY, 10591, USA
| | - Carmelo Romano
- Department of Ophthalmology, Regeneron Pharmaceuticals Inc, Tarrytown, NY, 10591, USA
| | - Nicholas W Gale
- Department of Pre-Therapeutic Target Discovery, Regeneron Pharmaceuticals Inc, Tarrytown, NY, 10591, USA
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31
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Zhou L, Köhncke C, Hu Z, Roepke TK, Abbott GW. The KCNE2 potassium channel β subunit is required for normal lung function and resilience to ischemia and reperfusion injury. FASEB J 2019; 33:9762-9774. [PMID: 31162977 DOI: 10.1096/fj.201802519r] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The KCNE2 single transmembrane-spanning voltage-gated potassium (Kv) channel β subunit is ubiquitously expressed and essential for normal function of a variety of cell types, often via regulation of the KCNQ1 Kv channel. A polymorphism upstream of KCNE2 is associated with reduced lung function in human populations, but the pulmonary consequences of KCNE2 gene disruption are unknown. Here, germline deletion of mouse Kcne2 reduced pulmonary expression of potassium channel α subunits Kcnq1 and Kcnb1 but did not alter expression of other Kcne genes. Kcne2 colocalized and coimmunoprecipitated with Kcnq1 in mouse lungs, suggesting the formation of pulmonary Kcnq1-Kcne2 potassium channel complexes. Kcne2 deletion reduced blood O2, increased CO2, increased pulmonary apoptosis, and increased inflammatory mediators TNF-α, IL-6, and leukocytes in bronchoalveolar lavage (BAL) fluids. Consistent with increased pulmonary vascular leakage, Kcne2 deletion increased plasma, BAL albumin, and the BAL:plasma albumin concentration ratio. Kcne2-/- mouse lungs exhibited baseline induction of the reperfusion injury salvage kinase pathway but were less able to respond via this pathway to imposed pulmonary ischemia/reperfusion injury (IRI). We conclude that KCNE2 regulates KCNQ1 in the lungs and is required for normal lung function and resistance to pulmonary IRI. Our data support a causal relationship between KCNE2 gene disruption and lung dysfunction.-Zhou, L., Köhncke, C., Hu, Z., Roepke, T. K., Abbott, G. W. The KCNE2 potassium channel β subunit is required for normal lung function and resilience to ischemia and reperfusion injury.
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Affiliation(s)
- Leng Zhou
- Department of Anesthesiology, West China Hospital, Sichuan University, Chengdu, China
| | - Clemens Köhncke
- Experimental and Clinical Research Center, Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Zhaoyang Hu
- Laboratory of Anesthesiology and Critical Care Medicine, Translational Neuroscience Center, West China Hospital, Sichuan University, Chengdu, China
| | - Torsten K Roepke
- Experimental and Clinical Research Center, Max Delbrück Center for Molecular Medicine, Berlin, Germany.,Clinic for Cardiology and Angiology, Charité-Berlin University of Medicine Campus Mitte, Berlin, Germany.,Clinic for Internal Medicine and Cardiology Klinikum Niederlausitz, Senftenberg, Germany
| | - Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California-Irvine, Irvine, California, USA
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32
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Law CL, Sanders CR. NMR resonance assignments and secondary structure of a mutant form of the human KCNE1 channel accessory protein that exhibits KCNE3-like function. BIOMOLECULAR NMR ASSIGNMENTS 2019; 13:143-147. [PMID: 30603955 PMCID: PMC6440842 DOI: 10.1007/s12104-018-09867-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 12/13/2018] [Indexed: 06/09/2023]
Abstract
KCNQ1 (Q1) is a voltage-gated potassium channel that is modulated by members of the KCNE family, the best-characterized being KCNE1 (E1) and KCNE3 (E3). The Q1/E1 complex generates a channel with delayed activation and increased conductance. This complex is expressed in cardiomyocytes where it provides the IKs current that is critical for the repolarization phase of the cardiac action potential. The Q1/E3 complex, on the other hand, is expressed in epithelial cells of the colon and stomach, where it serves as a constitutively active leak channel to help maintain water and ion homeostasis. Studies show the single transmembrane segments (TMS) present in both E1 and E3 are essential to their distinct functions. More specifically, residues FTL located near the middle of the E1 TMS are essential for the delayed activation of Q1, while the corresponding TVG sites in E3 are critical for constitutive activation of the channel. Swapping these three residues leads to the switching of the functional properties for both Q1/E1FTL→TVG and Q1/E3TVG→FTL complexes. This work details the backbone assignments and chemical shifts for the E1FTL→TVG mutant, as determined using a suite of 3D NMR experiments along with specific and inverse amino acid isotopic labeling. The completed assignments can be used, in conjunction with other NMR experiments, to generate a 3D structure of E1FTL→TVG. The results of TALOS-N analysis of the chemical shifts are reported here. The E1FTL→TVG structure will be compared to the already available E1 and E3 structures to determine the roles that their TMS triplet motifs play in each protein to dictate their distinct channel-modulatory functions.
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Affiliation(s)
- Cheryl L Law
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, 37240-7917, USA
| | - Charles R Sanders
- Department of Biochemistry and Center for Structural Biology, Vanderbilt University School of Medicine Basic Sciences, Nashville, TN, 37240-7917, USA.
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33
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Faridi R, Tona R, Brofferio A, Hoa M, Olszewski R, Schrauwen I, Assir MZ, Bandesha AA, Khan AA, Rehman AU, Brewer C, Ahmed W, Leal SM, Riazuddin S, Boyden SE, Friedman TB. Mutational and phenotypic spectra of KCNE1 deficiency in Jervell and Lange-Nielsen Syndrome and Romano-Ward Syndrome. Hum Mutat 2019; 40:162-176. [PMID: 30461122 PMCID: PMC6328321 DOI: 10.1002/humu.23689] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Revised: 11/01/2018] [Accepted: 11/15/2018] [Indexed: 11/11/2022]
Abstract
KCNE1 encodes a regulatory subunit of the KCNQ1 potassium channel-complex. Both KCNE1 and KCNQ1 are necessary for normal hearing and cardiac ventricular repolarization. Recessive variants in these genes are associated with Jervell and Lange-Nielson syndrome (JLNS1 and JLNS2), a cardio-auditory syndrome characterized by congenital profound sensorineural deafness and a prolonged QT interval that can cause ventricular arrhythmias and sudden cardiac death. Some normal-hearing carriers of heterozygous missense variants of KCNE1 and KCNQ1 have prolonged QT intervals, a dominantly inherited phenotype designated Romano-Ward syndrome (RWS), which is also associated with arrhythmias and elevated risk of sudden death. Coassembly of certain mutant KCNE1 monomers with wild-type KCNQ1 subunits results in RWS by a dominant negative mechanism. This paper reviews variants of KCNE1 and their associated phenotypes, including biallelic truncating null variants of KCNE1 that have not been previously reported. We describe three homozygous nonsense mutations of KCNE1 segregating in families ascertained ostensibly for nonsyndromic deafness: c.50G>A (p.Trp17*), c.51G>A (p.Trp17*), and c.138C>A (p.Tyr46*). Some individuals carrying missense variants of KCNE1 have RWS. However, heterozygotes for loss-of-function variants of KCNE1 may have normal QT intervals while biallelic null alleles are associated with JLNS2, indicating a complex genotype-phenotype spectrum for KCNE1 variants.
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Affiliation(s)
- Rabia Faridi
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore 54550, Pakistan
| | - Risa Tona
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
| | - Alessandra Brofferio
- Cardiology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health Clinical Center, Bethesda, MD 20892, USA
| | - Michael Hoa
- Auditory Development and Restoration Program, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
| | - Rafal Olszewski
- Auditory Development and Restoration Program, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
| | - Isabelle Schrauwen
- Center for Statistical Genetics, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Muhammad Z.K. Assir
- Allama Iqbal Medical Research Centre, Jinnah Hospital Complex, Lahore 54550, Pakistan
| | - Akhtar A. Bandesha
- Cardiology Department, The Pakistan Institute of Medical Sciences, Islamabad, Pakistan
| | - Asma A. Khan
- National Centre of Excellence in Molecular Biology, University of the Punjab, Lahore 54550, Pakistan
| | - Atteeq U. Rehman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
| | - Carmen Brewer
- Audiology Unit, National Institute on Deafness and Other Communication Disorders (NIDCD), National Institutes of Health, Bethesda, MD 20892, USA
| | - Wasim Ahmed
- Department of Biochemistry, Faculty of Biological Sciences, Quaid-i-Azam University, Islamabad 45320, Pakistan
| | - Suzanne M. Leal
- Center for Statistical Genetics, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Sheikh Riazuddin
- Allama Iqbal Medical Research Centre, Jinnah Hospital Complex, Lahore 54550, Pakistan
| | - Steven E. Boyden
- Section on Genetics of Communication Disorders, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
| | - Thomas B. Friedman
- Laboratory of Molecular Genetics, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, MD 20892, USA
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34
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Ramoz N. QT length during methadone maintenance treatment: Gene x dose interaction. Fundam Clin Pharmacol 2019; 33:94-95. [PMID: 30663143 DOI: 10.1111/fcp.12431] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Nicolas Ramoz
- INSERM UMR894, Center of Psychiatry and Neuroscience, 102-108 Rue de la Santé, 75014, Paris, France
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35
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Zerdazi EH, Vorspan F, Marees AT, Naccache F, Lepine JP, Laplanche JL, Prince N, Marie-Claire C, Bellivier F, Mouly S, Bloch V. QT length during methadone maintenance treatment: gene × dose interaction. Fundam Clin Pharmacol 2019; 33:96-106. [DOI: 10.1111/fcp.12405] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 07/04/2018] [Accepted: 08/01/2018] [Indexed: 12/11/2022]
Affiliation(s)
- El-Hadi Zerdazi
- INSERM U1144 Variabilité de réponse aux psychotropes; Université Paris Descartes; Université Paris Diderot; Université Sorbonne Paris Cité; Faculté de Pharmacie; 4 avenue de l'observatoire - 75006 Paris France
- APHP; Service d'addictologie; DHU Pe-PSY; Pôle de Psychiatrie et d'Addictologie des Hôpitaux Universitaires; Henri Mondor; F94000 Créteil France
| | - Florence Vorspan
- INSERM U1144 Variabilité de réponse aux psychotropes; Université Paris Descartes; Université Paris Diderot; Université Sorbonne Paris Cité; Faculté de Pharmacie; 4 avenue de l'observatoire - 75006 Paris France
- APHP; Département de Psychiatrie et de Médecine Addictologigue; Hôpital Fernand Widal; 75010 Paris France
| | - Andries T. Marees
- Department of Psychiatry, Amsterdam Neuroscience; Academic Medical Center; University of Amsterdam; Amsterdam The Netherlands
- QIMR Berghofer; Translational Neurogenomics Group; Brisbane Australia
| | - François Naccache
- INSERM U1144 Variabilité de réponse aux psychotropes; Université Paris Descartes; Université Paris Diderot; Université Sorbonne Paris Cité; Faculté de Pharmacie; 4 avenue de l'observatoire - 75006 Paris France
- APHP; Département de Psychiatrie et de Médecine Addictologigue; Hôpital Fernand Widal; 75010 Paris France
| | - Jean-Pierre Lepine
- INSERM U1144 Variabilité de réponse aux psychotropes; Université Paris Descartes; Université Paris Diderot; Université Sorbonne Paris Cité; Faculté de Pharmacie; 4 avenue de l'observatoire - 75006 Paris France
- APHP; Département de Psychiatrie et de Médecine Addictologigue; Hôpital Fernand Widal; 75010 Paris France
| | - Jean-Louis Laplanche
- INSERM U1144 Variabilité de réponse aux psychotropes; Université Paris Descartes; Université Paris Diderot; Université Sorbonne Paris Cité; Faculté de Pharmacie; 4 avenue de l'observatoire - 75006 Paris France
| | - Nathalie Prince
- INSERM U1144 Variabilité de réponse aux psychotropes; Université Paris Descartes; Université Paris Diderot; Université Sorbonne Paris Cité; Faculté de Pharmacie; 4 avenue de l'observatoire - 75006 Paris France
| | - Cynthia Marie-Claire
- INSERM U1144 Variabilité de réponse aux psychotropes; Université Paris Descartes; Université Paris Diderot; Université Sorbonne Paris Cité; Faculté de Pharmacie; 4 avenue de l'observatoire - 75006 Paris France
| | - Frank Bellivier
- INSERM U1144 Variabilité de réponse aux psychotropes; Université Paris Descartes; Université Paris Diderot; Université Sorbonne Paris Cité; Faculté de Pharmacie; 4 avenue de l'observatoire - 75006 Paris France
- APHP; Département de Psychiatrie et de Médecine Addictologigue; Hôpital Fernand Widal; 75010 Paris France
- Fondation FondaMental; Fondation de coopération scientifique; Hôpital Albert Chenevier; 94000 Créteil France
| | - Stéphane Mouly
- INSERM U1144 Variabilité de réponse aux psychotropes; Université Paris Descartes; Université Paris Diderot; Université Sorbonne Paris Cité; Faculté de Pharmacie; 4 avenue de l'observatoire - 75006 Paris France
- Département de Médecine Interne; Hôpital Lariboisière; APHP; 75010 Paris France
| | - Vanessa Bloch
- INSERM U1144 Variabilité de réponse aux psychotropes; Université Paris Descartes; Université Paris Diderot; Université Sorbonne Paris Cité; Faculté de Pharmacie; 4 avenue de l'observatoire - 75006 Paris France
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36
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Li R, Miao J, Tabaran AF, O'Sullivan MG, Anderson KJ, Scott PM, Wang Z, Cormier RT. A novel cancer syndrome caused by KCNQ1-deficiency in the golden Syrian hamster. J Carcinog 2018; 17:6. [PMID: 30450013 PMCID: PMC6187935 DOI: 10.4103/jcar.jcar_5_18] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 07/31/2018] [Indexed: 12/18/2022] Open
Abstract
BACKGROUND The golden Syrian hamster is an emerging model organism. To optimize its use, our group has made the first genetically engineered hamsters. One of the first genes that we investigated is KCNQ1 which encodes for the KCNQ1 potassium channel and also has been implicated as a tumor suppressor gene. MATERIALS AND METHODS We generated KCNQ1 knockout (KO) hamsters by CRISPR/Cas9-mediated gene targeting and investigated the effects of KCNQ1-deficiency on tumorigenesis. RESULTS By 70 days of age seven of the eight homozygous KCNQ1 KOs used in this study began showing signs of distress, and on necropsy six of the seven ill hamsters had visible cancers, including T-cell lymphomas, plasma cell tumors, hemangiosarcomas, and suspect myeloid leukemias. CONCLUSIONS None of the hamsters in our colony that were wild-type or heterozygous for KCNQ1 mutations developed cancers indicating that the cancer phenotype is linked to KCNQ1-deficiency. This study is also the first evidence linking KCNQ1-deficiency to blood cancers.
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Affiliation(s)
- Rong Li
- Department of Animal, Dairy, and Veterinary Sciences, Utah State University, Logan, Utah, USA
| | - Jinxin Miao
- Department of Animal, Dairy, and Veterinary Sciences, Utah State University, Logan, Utah, USA
| | - Alexandru-Flaviu Tabaran
- Veterinary Diagnostic Laboratory, College of Veterinary Medicine, University of Minnesota, Duluth, MN, USA.,Comparative Pathology Shared Resource, Masonic Cancer Center, University of Minnesota, Duluth, MN, USA
| | - M Gerard O'Sullivan
- Veterinary Diagnostic Laboratory, College of Veterinary Medicine, University of Minnesota, Duluth, MN, USA.,Comparative Pathology Shared Resource, Masonic Cancer Center, University of Minnesota, Duluth, MN, USA
| | - Kyle J Anderson
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, MN, USA
| | - Patricia M Scott
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, MN, USA
| | - Zhongde Wang
- Department of Animal, Dairy, and Veterinary Sciences, Utah State University, Logan, Utah, USA
| | - Robert T Cormier
- Department of Biomedical Sciences, University of Minnesota Medical School, Duluth, MN, USA
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37
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David JP, Lisewski U, Crump SM, Jepps TA, Bocksteins E, Wilck N, Lossie J, Roepke TK, Schmitt N, Abbott GW. Deletion in mice of X-linked, Brugada syndrome- and atrial fibrillation-associated Kcne5 augments ventricular K V currents and predisposes to ventricular arrhythmia. FASEB J 2018; 33:2537-2552. [PMID: 30289750 DOI: 10.1096/fj.201800502r] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
KCNE5 is an X-linked gene encoding KCNE5, an ancillary subunit to voltage-gated potassium (KV) channels. Human KCNE5 mutations are associated with atrial fibrillation (AF)- and Brugada syndrome (BrS)-induced cardiac arrhythmias that can arise from increased potassium current in cardiomyocytes. Seeking to establish underlying molecular mechanisms, we created and studied Kcne5 knockout ( Kcne5-/0) mice. Intracardiac ECG revealed that Kcne5 deletion caused ventricular premature beats, increased susceptibility to induction of polymorphic ventricular tachycardia (60 vs. 24% in Kcne5+/0 mice), and 10% shorter ventricular refractory period. Kcne5 deletion increased mean ventricular myocyte KV current density in the apex and also in the subpopulation of septal myocytes that lack fast transient outward current ( Ito,f). The current increases arose from an apex-specific increase in slow transient outward current-1 ( IKslow,1) (conducted by KV1.5) and Ito,f (conducted by KV4) and an increase in IKslow,2 (conducted by KV2.1) in both apex and septum. Kcne5 protein localized to the intercalated discs in ventricular myocytes, where KV2.1 was also detected in both Kcne5-/0 and Kcne5+/0 mice. In HL-1 cardiac cells and human embryonic kidney cells, KCNE5 and KV2.1 colocalized at the cell surface, but predominantly in intracellular vesicles, suggesting that Kcne5 deletion increases IK,slow2 by reducing KV2.1 intracellular sequestration. The human AF-associated mutation KCNE5-L65F negative shifted the voltage dependence of KV2.1-KCNE5 channels, increasing their maximum current density >2-fold, whereas BrS-associated KCNE5 mutations produced more subtle negative shifts in KV2.1 voltage dependence. The findings represent the first reported native role for Kcne5 and the first demonstrated Kcne regulation of KV2.1 in mouse heart. Increased KV current is a manifestation of KCNE5 disruption that is most likely common to both mouse and human hearts, providing a plausible mechanistic basis for human KCNE5-linked AF and BrS.-David, J.-P., Lisewski, U., Crump, S. M., Jepps, T. A., Bocksteins, E., Wilck, N., Lossie, J., Roepke, T. K., Schmitt, N., Abbott, G. W. Deletion in mice of X-linked, Brugada syndrome- and atrial fibrillation-associated Kcne5 augments ventricular KV currents and predisposes to ventricular arrhythmia.
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Affiliation(s)
- Jens-Peter David
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark.,Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ulrike Lisewski
- Medical Clinic and Polyclinic for Cardiology and Angiology, Charité Medical University of Berlin, Berlin, Germany.,Experimental and Clinical Research Center (ECRC), Charité Medical University of Berlin, Berlin, Germany
| | - Shawn M Crump
- Bioelectricity Laboratory, Department of Physiology and Biophysics, University of California, Irvine, Irvine, California, USA; and
| | - Thomas A Jepps
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark.,Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Elke Bocksteins
- Laboratory for Molecular Biophysics, Physiology, and Pharmacology, Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
| | - Nicola Wilck
- Medical Clinic and Polyclinic for Cardiology and Angiology, Charité Medical University of Berlin, Berlin, Germany.,Experimental and Clinical Research Center (ECRC), Charité Medical University of Berlin, Berlin, Germany
| | - Janine Lossie
- Medical Clinic and Polyclinic for Cardiology and Angiology, Charité Medical University of Berlin, Berlin, Germany.,Experimental and Clinical Research Center (ECRC), Charité Medical University of Berlin, Berlin, Germany
| | - Torsten K Roepke
- Medical Clinic and Polyclinic for Cardiology and Angiology, Charité Medical University of Berlin, Berlin, Germany.,Experimental and Clinical Research Center (ECRC), Charité Medical University of Berlin, Berlin, Germany
| | - Nicole Schmitt
- Danish National Research Foundation Centre for Cardiac Arrhythmia, University of Copenhagen, Copenhagen, Denmark.,Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, University of California, Irvine, Irvine, California, USA; and
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38
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Huang H, Kuenze G, Smith JA, Taylor KC, Duran AM, Hadziselimovic A, Meiler J, Vanoye CG, George AL, Sanders CR. Mechanisms of KCNQ1 channel dysfunction in long QT syndrome involving voltage sensor domain mutations. SCIENCE ADVANCES 2018; 4:eaar2631. [PMID: 29532034 PMCID: PMC5842040 DOI: 10.1126/sciadv.aar2631] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 02/02/2018] [Indexed: 05/21/2023]
Abstract
Mutations that induce loss of function (LOF) or dysfunction of the human KCNQ1 channel are responsible for susceptibility to a life-threatening heart rhythm disorder, the congenital long QT syndrome (LQTS). Hundreds of KCNQ1 mutations have been identified, but the molecular mechanisms responsible for impaired function are poorly understood. We investigated the impact of 51 KCNQ1 variants with mutations located within the voltage sensor domain (VSD), with an emphasis on elucidating effects on cell surface expression, protein folding, and structure. For each variant, the efficiency of trafficking to the plasma membrane, the impact of proteasome inhibition, and protein stability were assayed. The results of these experiments combined with channel functional data provided the basis for classifying each mutation into one of six mechanistic categories, highlighting heterogeneity in the mechanisms resulting in channel dysfunction or LOF. More than half of the KCNQ1 LOF mutations examined were seen to destabilize the structure of the VSD, generally accompanied by mistrafficking and degradation by the proteasome, an observation that underscores the growing appreciation that mutation-induced destabilization of membrane proteins may be a common human disease mechanism. Finally, we observed that five of the folding-defective LQTS mutant sites are located in the VSD S0 helix, where they interact with a number of other LOF mutation sites in other segments of the VSD. These observations reveal a critical role for the S0 helix as a central scaffold to help organize and stabilize the KCNQ1 VSD and, most likely, the corresponding domain of many other ion channels.
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Affiliation(s)
- Hui Huang
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37240, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
| | - Georg Kuenze
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37240, USA
| | - Jarrod A. Smith
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37240, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
| | - Keenan C. Taylor
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37240, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
| | - Amanda M. Duran
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37240, USA
| | - Arina Hadziselimovic
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37240, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
| | - Jens Meiler
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
- Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA
- Department of Pharmacology, Vanderbilt University, Nashville, TN 37240, USA
- Department of Bioinformatics, Vanderbilt University Medical Center, Nashville, TN 37232, USA
| | - Carlos G. Vanoye
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Alfred L. George
- Department of Pharmacology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA
| | - Charles R. Sanders
- Department of Biochemistry, Vanderbilt University, Nashville, TN 37240, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN 37240, USA
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232, USA
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39
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Trotta MC, Salerno M, Brigida AL, Monda V, Messina A, Fiore C, Avola R, Bernardini R, Sessa F, Marsala G, Zanghì GN, Messina G, D'Amico M, Di Filippo C. Inhibition of aldose-reductase-2 by a benzofuroxane derivative bf-5m increases the expression of kcne1, kcnq1 in high glucose cultured H9c2 cardiac cells and sudden cardiac death. Oncotarget 2017; 9:17257-17269. [PMID: 29707106 PMCID: PMC5915114 DOI: 10.18632/oncotarget.23270] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2017] [Accepted: 12/08/2017] [Indexed: 12/20/2022] Open
Abstract
Long QT syndrome (LQTS) is characterized by prolonged QT interval, leading to sudden cardiac death. Hyperglycemia is an important risk factor for LQTS, inhibiting the cardiac rapid component delayed rectifier K+ current (Iks), responsible for QT interval. We previously showed that the new ALR2 inhibitor BF-5m supplies cardioprotection from QT prolongation induced by high glucose concentration in the medium, reducing QT interval prolongation and preserving morphology. Here we investigated the effects of BF-5m on cell cytotoxicity and viability in H9c2 cells, and on cellular potassium ion channels expression. H9c2 cells were grown in medium with high glucose and high glucose plus the BF-5m by assessing the cytotoxic effects and the cell survival rate. In addition, KCNE1 and KCNQ1 expression in plasma and mitochondrial membranes were monitored. Also, the expression levels of miR-1 proved to suppress KCNQ1 and KCNE1, were analyzed. BF-5m treatment reduced the cytotoxic effects of high glucose on H9c2 cells by increasing cell survival rate and improving H9c2 morphology. Plasmatic KCNE1 and KCNQ1 expression levels were restored by BF-5m in H9c2 exposed to high glucose, down-regulating miR-1. These results suggest that BF-5m exerts cardioprotection from high glucose in rat heart ventricle H9c2 cells exposed to high glucose.
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Affiliation(s)
- Maria Consiglia Trotta
- Department of Experimental Medicine, Division of Pharmacology, University of Campania L. Vanvitelli, Naples, Italy
| | - Monica Salerno
- Department of Clinical and Experimental Medicine University of Foggia, Foggia, Italy
| | - Anna Lisa Brigida
- Department of Experimental Medicine, Division of Pharmacology, University of Campania L. Vanvitelli, Naples, Italy
| | - Vincenzo Monda
- Department of Experimental Medicine, Section of Human Physiology and Dietetic and Sport Medicine, University of Campania L. Vanvitelli, Naples, Italy
| | - Antonietta Messina
- Department of Experimental Medicine, Section of Human Physiology and Dietetic and Sport Medicine, University of Campania L. Vanvitelli, Naples, Italy
| | - Carmela Fiore
- Department of Clinical and Experimental Medicine University of Foggia, Foggia, Italy
| | - Roberto Avola
- Department of Biomedical and Biotecnological Sciences, University of Catania, Catania, Italy
| | - Renato Bernardini
- Department of Biomedical and Biotecnological Sciences, University of Catania, Catania, Italy
| | - Francesco Sessa
- Department of Clinical and Experimental Medicine University of Foggia, Foggia, Italy
| | - Gabriella Marsala
- Struttura Complessa di Farmacia, Azienda Ospedaliero-Universitaria, Ospedali Riuniti di Foggia, Foggia, Italy
| | - Guido N Zanghì
- Department of Surgery, Policlinico Vittorio Emanuele University Hospital, University of Catania, Catania, Sicily, Italy
| | - Giovanni Messina
- Department of Clinical and Experimental Medicine University of Foggia, Foggia, Italy
| | - Michele D'Amico
- Department of Experimental Medicine, Division of Pharmacology, University of Campania L. Vanvitelli, Naples, Italy
| | - Clara Di Filippo
- Department of Experimental Medicine, Division of Pharmacology, University of Campania L. Vanvitelli, Naples, Italy
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40
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Fosmo AL, Skraastad ØB. The Kv7 Channel and Cardiovascular Risk Factors. Front Cardiovasc Med 2017; 4:75. [PMID: 29259974 PMCID: PMC5723334 DOI: 10.3389/fcvm.2017.00075] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Accepted: 11/21/2017] [Indexed: 12/30/2022] Open
Abstract
Potassium channels play a pivotal role in the regulation of excitability in cells such as neurons, cardiac myocytes, and vascular smooth muscle cells. The KCNQ (Kv7) family of voltage-activated K+ channels hyperpolarizes the cell and stabilizes the membrane potential. Here, we outline how Kv7 channel activity may contribute to the development of the cardiovascular risk factors such as hypertension, diabetes, and obesity. Questions and hypotheses regarding previous and future research have been raised. Alterations in the Kv7 channel may contribute to the development of cardiovascular disease (CVD). Pharmacological modification of Kv7 channels may represent a possible treatment for CVD in the future.
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Affiliation(s)
- Andreas L Fosmo
- Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
| | - Øyvind B Skraastad
- Division of Physiology, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway
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41
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Inactivation of KCNQ1 potassium channels reveals dynamic coupling between voltage sensing and pore opening. Nat Commun 2017; 8:1730. [PMID: 29167462 PMCID: PMC5700111 DOI: 10.1038/s41467-017-01911-8] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2017] [Accepted: 10/25/2017] [Indexed: 12/04/2022] Open
Abstract
In voltage-activated ion channels, voltage sensor (VSD) activation induces pore opening via VSD-pore coupling. Previous studies show that the pore in KCNQ1 channels opens when the VSD activates to both intermediate and fully activated states, resulting in the intermediate open (IO) and activated open (AO) states, respectively. It is also well known that accompanying KCNQ1 channel opening, the ionic current is suppressed by a rapid process called inactivation. Here we show that inactivation of KCNQ1 channels derives from the different mechanisms of the VSD-pore coupling that lead to the IO and AO states, respectively. When the VSD activates from the intermediate state to the activated state, the VSD-pore coupling has less efficacy in opening the pore, producing inactivation. These results indicate that different mechanisms, other than the canonical VSD-pore coupling, are at work in voltage-dependent ion channel activation. KCNQ1 is a voltage-gated potassium channel that is important in cardiac and epithelial function. Here the authors present a mechanism for KCNQ1 activation and inactivation in which voltage sensor activation promotes pore opening more effectively in the intermediate open state than the fully open state, generating inactivation.
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42
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Talin-1 interaction network promotes hepatocellular carcinoma progression. Oncotarget 2017; 8:13003-13014. [PMID: 28099903 PMCID: PMC5355072 DOI: 10.18632/oncotarget.14674] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2016] [Accepted: 01/09/2017] [Indexed: 12/30/2022] Open
Abstract
Talin-1 is a known oncogene-associated protein. In this study, we set out to determine its role and mechanisms in hepatocellular carcinoma (HCC) progression. We found Talin-1 to be highly expressed in HCC cells relative to non-cancer liver epithelial cells and to promote tumor growth and metastasis. We used Whole Human Genome Oligo Microarray analysis with HCC cells and HCC cells in which Talin-1 was knocked down using shRNA to identify transcripts regulated by Talin-1. Of the 40,000 tested genes, 3099 were differentially expressed after Talin-1 knockdown; expression of 1924 genes was increased, while expression of 2175 was decreased. Gene ontology (GO) profiling indicated that Talin-1 promotes many HCC progression-related activities, including ion transport and membrane depolarization, cell growth, and cell adhesion. We also characterized the network of gene transcripts regulated by Talin-1 and their role in promoting HCC progression. Our findings confirm the role of Talin-1 in carcinogenesis and provided a set of novel therapeutic targets for the treatment of HCC.
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43
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Abbott GW. β Subunits Control the Effects of Human Kv4.3 Potassium Channel Phosphorylation. Front Physiol 2017; 8:646. [PMID: 28919864 PMCID: PMC5585193 DOI: 10.3389/fphys.2017.00646] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 08/16/2017] [Indexed: 11/17/2022] Open
Abstract
The transient outward K+ current, Ito, activates early in the cardiac myocyte action potential, to begin repolarization. Human Ito is generated primarily by two Kv4.3 potassium channel α subunit splice variants (Kv4.3L and Kv4.3S) that diverge only by a C-terminal, membrane-proximal, 19-residue stretch unique to Kv4.3L. Protein kinase C (PKC) phosphorylation of threonine 504 within the Kv4.3L-specific 19-residues mediates α-adrenergic inhibition of Ito in human heart. Kv4.3 is regulated in human heart by various β subunits, including cytosolic KChIP2b and transmembrane KCNEs, yet their impact on the functional effects of human Kv4.3 phosphorylation has not been reported. Here, this gap in knowledge was addressed using human Kv4.3 splice variants, T504 mutants, and human β subunits. Subunits were co-expressed in Xenopus laevis oocytes and analyzed by two-electrode voltage-clamp, using phorbol 12-myristate 13-acetate (PMA) to stimulate PKC. Unexpectedly, KChIP2b removed the inhibitory effect of PKC on Kv4.3L (but not Kv4.3L threonine phosphorylation by PKC per-se), while co-expression with KCNE2, but not KCNE4, restored PKC-dependent inhibition of Kv4.3L-KChIP2b to quantitatively resemble previously reported effects of α-adrenergic modulation of human ventricular Ito. In addition, PKC accelerated recovery from inactivation of Kv4.3L-KChIP2b channels and, interestingly, of both Kv4.3L and Kv4.3S alone. Thus, β subunits regulate the response of human Kv4.3 to PKC phosphorylation and provide a potential mechanism for modifying the response of Ito to α-adrenergic regulation in vivo.
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Affiliation(s)
- Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, IrvineIrvine, CA, United States
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44
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SMIT1 Modifies KCNQ Channel Function and Pharmacology by Physical Interaction with the Pore. Biophys J 2017; 113:613-626. [PMID: 28793216 DOI: 10.1016/j.bpj.2017.06.055] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Revised: 05/26/2017] [Accepted: 06/12/2017] [Indexed: 11/22/2022] Open
Abstract
Voltage-gated potassium channels of the KCNQ (Kv7) subfamily are essential for control of cellular excitability and repolarization in a wide range of cell types. Recently, we and others found that some KCNQ channels functionally and physically interact with sodium-dependent solute transporters, including myo-inositol transporters SMIT1 and SMIT2, potentially facilitating various modes of channel-transporter signal integration. In contrast to indirect effects such as channel regulation by SMIT-transported, myo-inositol-derived phosphatidylinositol 4,5-bisphosphate (PIP2), the mechanisms and functional consequences of the physical interaction of channels with transporters have been little studied. Here, using co-immunoprecipitation with different channel domains, we found that SMIT1 binds to the KCNQ2 pore module. We next tested the effects of SMIT1 co-expression, in the absence of extracellular myo-inositol or other SMIT1 substrates, on fundamental functional attributes of KCNQ2, KCNQ2/3, KCNQ1, and KCNQ1-KCNE1 channels. Without exception, SMIT1 altered KCNQ ion selectivity, sensitivity to extracellular K+, and pharmacology, consistent with an impact on conformation of the KCNQ pore. SMIT1 also altered the gating kinetics and/or voltage dependence of KCNQ2, KCNQ2/3, and KCNQ1-KCNE1. In contrast, SMIT1 had no effect on Kv1.1 (KCNA1) gating, ion selectivity, or pharmacology. We conclude that, independent of its transport activity and indirect regulatory mechanisms involving inositol-derived increases in PIP2, SMIT1, and likely other related sodium-dependent solute transporters, regulates KCNQ channel ion selectivity, gating, and pharmacology by direct physical interaction with the pore module.
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45
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Abbott GW. Chansporter complexes in cell signaling. FEBS Lett 2017; 591:2556-2576. [PMID: 28718502 DOI: 10.1002/1873-3468.12755] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 07/03/2017] [Accepted: 07/12/2017] [Indexed: 12/11/2022]
Abstract
Ion channels facilitate diffusion of ions across cell membranes for such diverse purposes as neuronal signaling, muscular contraction, and fluid homeostasis. Solute transporters often utilize ionic gradients to move aqueous solutes up their concentration gradient, also fulfilling a wide variety of tasks. Recently, an increasing number of ion channel-transporter ('chansporter') complexes have been discovered. Chansporter complex formation may overcome what could otherwise be considerable spatial barriers to rapid signal integration and feedback between channels and transporters, the ions and other substrates they transport, and environmental factors to which they must respond. Here, current knowledge in this field is summarized, covering both heterologous expression structure/function findings and potential mechanisms by which chansporter complexes fulfill contrasting roles in cell signaling in vivo.
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Affiliation(s)
- Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, CA, USA
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46
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Abbott GW. β Subunits Functionally Differentiate Human Kv4.3 Potassium Channel Splice Variants. Front Physiol 2017; 8:66. [PMID: 28228734 PMCID: PMC5296356 DOI: 10.3389/fphys.2017.00066] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 01/24/2017] [Indexed: 11/22/2022] Open
Abstract
The human ventricular cardiomyocyte transient outward K+ current (Ito) mediates the initial phase of myocyte repolarization and its disruption is implicated in Brugada Syndrome and heart failure (HF). Human cardiac Ito is generated primarily by two Kv4.3 splice variants (Kv4.3L and Kv4.3S, diverging only by a C-terminal, S6-proximal, 19-residue stretch unique to Kv4.3L), which are differentially remodeled in HF, but considered functionally alike at baseline. Kv4.3 is regulated in human heart by β subunits including KChIP2b and KCNEs, but their effects were previously assumed to be Kv4.3 isoform-independent. Here, this assumption was tested experimentally using two-electrode voltage-clamp analysis of human subunits co-expressed in Xenopus laevis oocytes. Unexpectedly, Kv4.3L-KChIP2b channels exhibited up to 8-fold lower current augmentation, 40% slower inactivation, and 5 mV-shifted steady-state inactivation compared to Kv4.3S-KChIP2b. A synthetic peptide mimicking the 19-residue stretch diminished these differences, reinforcing the importance of this segment in mediating Kv4.3 regulation by KChIP2b. KCNE subunits induced further functional divergence, including a 7-fold increase in Kv4.3S-KCNE4-KChIP2b current compared to Kv4.3L-KCNE4-KChIP2b. The discovery of β-subunit-dependent functional divergence in human Kv4.3 splice variants suggests a C-terminal signaling hub is crucial to governing β-subunit effects upon Kv4.3, and demonstrates the potential significance of differential Kv4.3 gene-splicing and β subunit expression in myocyte physiology and pathobiology.
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Affiliation(s)
- Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Pharmacology and Department of Physiology and Biophysics, School of Medicine, University of California, Irvine Irvine, CA, USA
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47
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Regulation of human cardiac potassium channels by full-length KCNE3 and KCNE4. Sci Rep 2016; 6:38412. [PMID: 27922120 PMCID: PMC5138848 DOI: 10.1038/srep38412] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Accepted: 11/09/2016] [Indexed: 12/23/2022] Open
Abstract
Voltage-gated potassium (Kv) channels comprise pore-forming α subunits and a multiplicity of regulatory proteins, including the cardiac-expressed and cardiac arrhythmia-linked transmembrane KCNE subunits. After recently uncovering novel, N-terminally extended (L) KCNE3 and KCNE4 isoforms and detecting their transcripts in human atrium, reported here are their functional effects on human cardiac Kv channel α subunits expressed in Xenopus laevis oocytes. As previously reported for short isoforms KCNE3S and KCNE4S, KCNE3L inhibited hERG; KCNE4L inhibited Kv1.1; neither form regulated the HCN1 pacemaker channel. Unlike KCNE4S, KCNE4L was a potent inhibitor of Kv4.2 and Kv4.3; co-expression of cytosolic β subunit KChIP2, which regulates Kv4 channels in cardiac myocytes, partially relieved Kv4.3 but not Kv4.2 inhibition. Inhibition of Kv4.2 and Kv4.3 by KCNE3L was weaker, and its inhibition of Kv4.2 abolished by KChIP2. KCNE3L and KCNE4L also exhibited subunit-specific effects on Kv4 channel complex inactivation kinetics, voltage dependence and recovery. Further supporting the potential physiological significance of the robust functional effects of KCNE4L on Kv4 channels, KCNE4L protein was detected in human atrium, where it co-localized with Kv4.3. The findings establish functional effects of novel human cardiac-expressed KCNE isoforms and further contribute to our understanding of the potential mechanisms influencing cardiomyocyte repolarization.
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48
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McKinnon D, Rosati B. Transmural gradients in ion channel and auxiliary subunit expression. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2016; 122:165-186. [PMID: 27702655 DOI: 10.1016/j.pbiomolbio.2016.09.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2016] [Accepted: 09/30/2016] [Indexed: 12/11/2022]
Abstract
Evolution has acted to shape the action potential in different regions of the heart in order to produce a maximally stable and efficient pump. This has been achieved by creating regional differences in ion channel expression levels within the heart as well as differences between equivalent cardiac tissues in different species. These region- and species-dependent differences in channel expression are established by regulatory evolution, evolution of the regulatory mechanisms that control channel expression levels. Ion channel auxiliary subunits are obvious targets for regulatory evolution, in order to change channel expression levels and/or modify channel function. This review focuses on the transmural gradients of ion channel expression in the heart and the role that regulation of auxiliary subunit expression plays in generating and shaping these gradients.
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Affiliation(s)
- David McKinnon
- Department of Veterans Affairs Medical Center, Northport, NY, USA; Institute of Molecular Cardiology, Stony Brook University, Stony Brook, NY, USA; Department of Neurobiology and Behavior, Stony Brook University, Stony Brook, NY, 11794, USA
| | - Barbara Rosati
- Department of Veterans Affairs Medical Center, Northport, NY, USA; Institute of Molecular Cardiology, Stony Brook University, Stony Brook, NY, USA; Department of Physiology and Biophysics, Stony Brook University, Stony Brook, NY, 11794, USA.
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49
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The Effects of Puerarin on Rat Ventricular Myocytes and the Potential Mechanism. Sci Rep 2016; 6:35475. [PMID: 27762288 PMCID: PMC5071873 DOI: 10.1038/srep35475] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Accepted: 09/28/2016] [Indexed: 12/22/2022] Open
Abstract
Puerarin, a known isoflavone, is commonly found as a Chinese herb medicine. It is widely used in China to treat cardiac diseases such as angina, cardiac infarction and arrhythmia. However, its cardioprotective mechanism remains unclear. In this study, puerarin significantly prolonged ventricular action potential duration (APD) with a dosage dependent manner in the micromolar range on isolated rat ventricular myocytes. However, submicromolar puerarin had no effect on resting membrane potential (RMP), action potential amplitude (APA) and maximal velocity of depolarization (Vmax) of action potential. Only above the concentration of 10 mM, puerarin exhibited more aggressive effect on action potential, and shifted RMP to the positive direction. Millimolar concentrations of puerarin significantly inhibited inward rectified K+ channels in a dosage dependent manner, and exhibited bigger effects upon Kir2.1 vs Kir2.3 in transfected HEK293 cells. As low as micromolar range concentrations of puerarin significantly inhibited Kv7.1 and IKs. These inhibitory effects may due to the direct inhibition of puerarin upon channels not via the PKA-dependent pathway. These results provided direct preclinical evidence that puerarin prolonged APD via its inhibitory effect upon Kv7.1 and IKs, contributing to a better understanding the mechanism of puerarin cardioprotection in the treatment of cardiovascular diseases.
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50
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Abbott GW, Jepps TA. Kcne4 Deletion Sex-Dependently Alters Vascular Reactivity. J Vasc Res 2016; 53:138-148. [PMID: 27710966 DOI: 10.1159/000449060] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Accepted: 08/10/2016] [Indexed: 01/06/2023] Open
Abstract
Voltage-gated potassium (Kv) channels formed by Kv7 (KCNQ) α-subunits are recognized as crucial for vascular smooth muscle function, in addition to their established roles in the heart (Kv7.1) and the brain (Kv7.2-5). In vivo, Kv7 α-subunits are often regulated by KCNE subfamily ancillary (β) subunits. We investigated the effects of targeted germline Kcne4 deletion on mesenteric artery reactivity in adult male and female mice. Kcne4 deletion increased mesenteric artery contractility in response to α-adrenoceptor agonist methoxamine, and decreased responses to Kv7.2-7.5 channel activator ML213, in male but not female mice. In contrast, Kcne4 deletion markedly decreased vasorelaxation in response to isoprenaline in both male and female mice. Kcne4 expression was 2-fold lower in the female versus the male mouse mesenteric artery, and Kcne4 deletion elicited only moderate changes of other Kcne transcripts, with no striking sex-specific differences. However, Kv7.4 protein expression in females was twice that in males, and was reduced in both sexes by Kcne4 deletion. Our findings confirm a crucial role for KCNE4 in regulation of Kv7 channel activity to modulate vascular tone, and provide the first known molecular mechanism for sex-specificity of this modulation that has important implications for vascular reactivity and may underlie sex-specific susceptibility to cardiovascular diseases.
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Affiliation(s)
- Geoffrey W Abbott
- Bioelectricity Laboratory, Departments of Pharmacology and Physiology and Biophysics, School of Medicine, University of California, Irvine, Calif., USA
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