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Najari Beidokhti M, Bertalovitz AC, Ji W, McCormack J, Jeffries L, Sempou E, Khokha MK, McDonald TV, Lakhani SA. Functional testing for variant prioritization in a family with long QT syndrome. Mol Genet Genomics 2021; 296:823-36. [PMID: 33876311 DOI: 10.1007/s00438-021-01780-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 03/29/2021] [Indexed: 01/08/2023]
Abstract
Next-generation sequencing platforms are being increasingly applied in clinical genetic settings for evaluation of families with suspected heritable disease. These platforms potentially improve the diagnostic yield beyond that of disease-specific targeted gene panels, but also increase the number of rare or novel genetic variants that may confound precise diagnostics. Here, we describe a functional testing approach used to interpret the results of whole exome sequencing (WES) in a family presenting with syncope and sudden death. One individual had a prolonged QT interval on electrocardiogram (ECG) and carried a diagnosis of long QT syndrome (LQTS), but a second individual did not meet criteria for LQTS. Filtering WES results for uncommon variants with arrhythmia association identified four for further analyses. In silico analyses indicated that two of these variants, KCNH2 p.(Cys555Arg) and KCNQ1 p.(Arg293Cys), were likely to be causal in this family's LQTS. We subsequently performed functional characterization of these variants in a heterologous expression system. The expression of KCNQ1-Arg293Cys did not show a deleterious phenotype but KCNH2-Cys555Arg demonstrated a loss-of-function phenotype that was partially dominant. Our stepwise approach identified a precise genetic etiology in this family, which resulted in the establishment of a LQTS diagnosis in the second individual as well as an additional asymptomatic family member, enabling personalized clinical management. Given its ability to aid in the diagnosis, the application of functional characterization should be considered as a value adjunct to in silico analyses of WES.
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Abstract
Voltage gated ion channels (VGICs) shape the electrical character of cells by undergoing structural changes in response to membrane depolarization. High-resolution techniques have provided a wealth of data on individual VGIC structures, but the conformational changes of endogenous channels in live cell membranes have remained unexplored. Here, we describe methods for imaging structural changes of voltage-gated K+ channels in living cells, using peptidyl toxins labeled with fluorophores that report specific protein conformations. These Endogenous Voltage-sensor Activity Probes (EVAPs) enable study of both VGIC allostery and function in the context of endogenous live-cell membranes under different physiological states. In this chapter, we describe methods for the synthesis, imaging, and analysis of dynamic EVAPs, which can report K+ channel activity in complex tissue preparations via 2-photon excitation microscopy, and environment-sensitive EVAPs, which report voltage-dependent conformational changes at the VGIC-toxin interface. The methods here present the utility of current EVAPs and lay the groundwork for the development of other probes that act by similar mechanisms. EVAPs can be correlated with electrophysiology, offering insight into the molecular details of endogenous channel function and allostery in live cells. This enables investigation of conformational changes of channels in their native, functional states, putting structures and models into a context of live-cell membranes. The expansive array of state-dependent ligands and optical probes should enable probes more generally for investigating the molecular motions of endogenous proteins.
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Affiliation(s)
- Robert Stewart
- Department of Physiology & Membrane Biology, University of California, Davis, CA, United States
| | - Bruce E Cohen
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, United States; Division of Molecular Biophysics & Integrated Bioimaging, Lawrence Berkeley National Laboratory, Berkeley, CA, United States.
| | - Jon T Sack
- Department of Physiology & Membrane Biology, University of California, Davis, CA, United States; Department of Anesthesiology & Pain Medicine, University of California, Davis, CA, United States.
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Kim HJ, Park S, Shin HY, Nam YR, Lam Hong PT, Chin YW, Nam JH, Kim WK. Inhibitory effects of α-Mangostin on T cell cytokine secretion via ORAI1 calcium channel and K + channels inhibition. PeerJ 2021; 9:e10973. [PMID: 33717700 PMCID: PMC7936567 DOI: 10.7717/peerj.10973] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 01/29/2021] [Indexed: 12/16/2022] Open
Abstract
Background As one of the main components of mangosteen (Garcinia mangostana), a tropical fruit, α-mangostin has been reported to have numerous pharmacological benefits such as anti-cancer, anti-inflammatory, and anti-allergic effects through various mechanisms of action. The effects of α-mangostin on intracellular signaling proteins is well studied, but the effects of α-mangostin on ion channels and its physiological effects in immune cells are unknown. Generation of intracellular calcium signaling is a fundamental step for T cell receptor stimulation. This signaling is mediated not only by the ORAI1 calcium channel, but also by potassium ion channels, which provide the electrical driving forces for generating sufficient calcium ion influx. This study investigated whether α-mangosteen suppress T cell stimulation by inhibiting ORAI1 and two kinds of potassium channels (Kv1.3 and KCa3.1), which are normally expressed in human T cells. Methods This study analyzed the inhibitory effect of α-mangostin on immune cell activity via inhibition of calcium and potassium ion channels expressed in immune cells. Results α-mangostin inhibited ORAI1 in a concentration-dependent manner, and the IC50 value was 1.27 ± 1.144 µM. Kv1.3 was suppressed by 41.38 ± 6.191% at 3 µM, and KCa3.1 was suppressed by 51.16 ± 5.385% at 3 µM. To measure the inhibition of cytokine secretion by immune cells, Jurkat T cells were stimulated to induce IL-2 secretion, and α-mangostin was found to inhibit it. This study demonstrated the anti-inflammatory effect of α-mangostin, the main component of mangosteen, through the regulation of calcium signals.
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Affiliation(s)
- Hyun Jong Kim
- Department of Physiology, Dongguk University College of Medicine, Gyeong-ju, Gyeongsangbuk-do, Republic of Korea.,Channelopathy Research Center (CRC), College of Medicine, Dongguk University, Goyang, Gyeonggi-do, Republic of Korea
| | - Seorin Park
- Department of Physiology, Dongguk University College of Medicine, Gyeong-ju, Gyeongsangbuk-do, Republic of Korea
| | - Hui Young Shin
- Department of Physiology, Dongguk University College of Medicine, Gyeong-ju, Gyeongsangbuk-do, Republic of Korea
| | - Yu Ran Nam
- Channelopathy Research Center (CRC), College of Medicine, Dongguk University, Goyang, Gyeonggi-do, Republic of Korea
| | - Phan Thi Lam Hong
- Department of Physiology, Dongguk University College of Medicine, Gyeong-ju, Gyeongsangbuk-do, Republic of Korea.,Channelopathy Research Center (CRC), College of Medicine, Dongguk University, Goyang, Gyeonggi-do, Republic of Korea
| | - Young-Won Chin
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, Republic of Korea
| | - Joo Hyun Nam
- Department of Physiology, Dongguk University College of Medicine, Gyeong-ju, Gyeongsangbuk-do, Republic of Korea.,Channelopathy Research Center (CRC), College of Medicine, Dongguk University, Goyang, Gyeonggi-do, Republic of Korea
| | - Woo Kyung Kim
- Channelopathy Research Center (CRC), College of Medicine, Dongguk University, Goyang, Gyeonggi-do, Republic of Korea.,Department of Internal Medicine Graduate School of Medicine, Dongguk University, Goyang, Gyeonggi-do, Republic of Korea
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Effertz T, Moser T, Oliver D. Recent advances in cochlear hair cell nanophysiology: subcellular compartmentalization of electrical signaling in compact sensory cells. Fac Rev 2021; 9:24. [PMID: 33659956 PMCID: PMC7886071 DOI: 10.12703/r/9-24] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In recent years, genetics, physiology, and structural biology have advanced into the molecular details of the sensory physiology of auditory hair cells. Inner hair cells (IHCs) and outer hair cells (OHCs) mediate two key functions: active amplification and non-linear compression of cochlear vibrations by OHCs and sound encoding by IHCs at their afferent synapses with the spiral ganglion neurons. OHCs and IHCs share some molecular physiology, e.g. mechanotransduction at the apical hair bundles, ribbon-type presynaptic active zones, and ionic conductances in the basolateral membrane. Unique features enabling their specific function include prestin-based electromotility of OHCs and indefatigable transmitter release at the highest known rates by ribbon-type IHC active zones. Despite their compact morphology, the molecular machineries that either generate electrical signals or are driven by these signals are essentially all segregated into local subcellular structures. This review provides a brief account on recent insights into the molecular physiology of cochlear hair cells with a specific focus on organization into membrane domains.
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Affiliation(s)
- Thomas Effertz
- InnerEarLab, Department of Otorhinolaryngology, University Medical Center Göttingen, 37099 Göttingen, Germany
| | - Tobias Moser
- Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen, 37099 Göttingen, Germany
- Auditory Neuroscience Group, Max Planck Institute for Experimental Medicine, 37075 Göttingen, Germany
- Synaptic Nanophysiology Group, Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
- Multiscale Bioimaging Cluster of Excellence (MBExC), University of Göttingen, 37075 Göttingen, Germany
| | - Dominik Oliver
- Institute for Physiology and Pathophysiology, Philipps University, Deutschhausstraße 2, 35037 Marburg, Germany
- Center for Mind, Brain and Behavior (CMBB), Universities of Marburg and Giessen, Germany
- DFG Research Training Group, Membrane Plasticity in Tissue Development and Remodelling, GRK 2213, Philipps University, Marburg, Germany
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Teng HW, Tani J, Chang TS, Chen HJ, Lin YC, Lin CS, Sung JY. Altered sensory nerve excitability in fibromyalgia. J Formos Med Assoc 2021; 120:1611-9. [PMID: 33642123 DOI: 10.1016/j.jfma.2021.02.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 12/23/2020] [Accepted: 02/02/2021] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND/PURPOSE To investigate nerve excitability changes in patients with fibromyalgia and the correlation with clinical severity. METHODS We enrolled 20 subjects with fibromyalgia and 22 sex and age-matched healthy subjects to receive nerve excitability test and nerve conduction study to evaluate the peripheral axonal function. RESULTS In the fibromyalgia cohort, the sensory axonal excitability test revealed increased superexcitability (%) (P = 0.029) compared to healthy control. Correlational study showed a negative correlation between increased subexcitability (%) (r = -0.534, P = 0.022) with fibromyalgia impact questionnaire (FIQ) score. Computer modeling confirmed that the sensory axon excitability pattern we observed in fibromyalgia cohort was best explained by increased Barrett-Barrett conductance, which was thought to be attributed to paranodal fast K+ channel dysfunction. CONCLUSION The present study revealed that paranodal sensory K+ conductance was altered in patients with fibromyalgia. The altered conductance indicated dysfunction of paranodal fast K+ channels, which is known to be associated with the generation of pain.
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Qin C, Wan X, Li S, Yang F, Yang L, Zuo Z, Cao Z, Chen Z, Wu Y. Different pharmacological properties between scorpion toxin BmKcug2 and its degraded analogs highlight the diversity of K + channel blockers from thermally processed scorpions. Int J Biol Macromol 2021; 178:143-153. [PMID: 33636268 DOI: 10.1016/j.ijbiomac.2021.02.155] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 02/16/2021] [Accepted: 02/20/2021] [Indexed: 11/16/2022]
Abstract
Novel degraded potassium channel-modulatory peptides were recently found in thermally processed scorpions, but their pharmacological properties remain unclear. Here, we identified a full-length scorpion toxin (i.e., BmKcug2) and its four truncated analogs (i.e., BmKcug2-P1, BmKcug2-P2, BmKcug2-P3 and BmKcug2-P4) with three conserved disulfide bonds in processed scorpion medicinal material by mass spectrometry. The pharmacological experiments revealed that the recombinant BmKcug2 and BmKcug2-P1 could selectively inhibit the human Kv1.2 and human Kv1.3 potassium channels, while the other three analogs showed a much weaker inhibitory effect on potassium channels. BmKcug2 inhibited hKv1.2 and hKv1.3 channels, with IC50 values of 45.6 ± 5.8 nM and 215.2 ± 39.7 nM, respectively, and BmKcug2-P1 inhibited hKv1.2 and hKv1.3, with IC50 values of 89.9 ± 9.6 nM and 1142.4 ± 64.5 nM, respectively. The chromatographic analysis and pharmacological properties of BmKcug2 and BmKcug2-P1 boiled in water for different times further strongly supported their good thermal stability. Structural and functional dissection indicated that one amino acid, i.e., Tyr36, determined the differential affinities of BmKcug2 and four BmKcug2 analogs. Altogether, this research investigated the different pharmacological properties of BmKcug2 and its truncated analogs, and the findings highlighted the diversity of K+ channel blockers from various scorpion species through thermal processing.
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Affiliation(s)
- Chenhu Qin
- College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Xiuping Wan
- College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Songryong Li
- College of Life Sciences, Wuhan University, Wuhan 430072, China; Department of Biotechnology, Institute for Life Science, Kim Hyong Jik University of Education, Pyongyang, Democratic People's Republic of Korea
| | - Fan Yang
- College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Liuting Yang
- College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Zheng Zuo
- Center for BioDrug Research, Wuhan University, Wuhan 430072, China
| | - Zhijian Cao
- College of Life Sciences, Wuhan University, Wuhan 430072, China; Center for BioDrug Research, Wuhan University, Wuhan 430072, China
| | - Zongyun Chen
- College of Life Sciences, Wuhan University, Wuhan 430072, China; Department of Biochemistry and Molecular Biology, College of Basic Medicine, Hubei University of Medicine, Shiyan 442000, China
| | - Yingliang Wu
- College of Life Sciences, Wuhan University, Wuhan 430072, China; Center for BioDrug Research, Wuhan University, Wuhan 430072, China.
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Oh JW, Lee CK, Whang K, Jeong SW. Functional plasticity of cardiac efferent neurons contributes to traumatic brain injury-induced cardiac autonomic dysfunction. Brain Res 2021; 1753:147257. [PMID: 33422529 DOI: 10.1016/j.brainres.2020.147257] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2020] [Revised: 12/17/2020] [Accepted: 12/18/2020] [Indexed: 10/22/2022]
Abstract
Traumatic brain injury (TBI) frequently causes cardiac autonomic dysfunction (CAD), irrespective of its severity, which is associated with an increased morbidity and mortality in patients. Despite the significance of probing the cellular mechanism underlying TBI-induced CAD, animal studies on this mechanism are lacking. In the current study, we tested whether TBI-induced CAD is associated with functional plasticity in cardiac efferent neurons. In this regard, TBI was induced by a controlled cortical impact in rats. Assessment of heart rate variability and baroreflex sensitivity indicated that CAD was developed in the sub-acute period after moderate and severe TBI. The cell excitability was increased in the stellate ganglion (SG) neurons and decreased in the intracardiac ganglion (ICG) neurons in TBI rats, compared with the sham-operated rats. The transient A-type K+ (KA) currents, but not the delayed rectifying K+ currents were significantly decreased in SG neurons in TBI rats, compared with sham-operated rats. Consistent with these electrophysiological data, the transcripts encoding the Kv4 α subunits were significantly downregulated in SG neurons in TBI rats, compared with sham-operated rats. TBI causes downregulation and upregulation of M-type K+ (KM) currents and the KCNQ2 mRNA transcripts, which may contribute to the hyperexcitability of the SG neurons and the hypoexcitability of the ICG neurons, respectively. In conclusion, the key cellular mechanism underlying the TBI-induced CAD may be the functional plasticity of the cardiac efferent neurons, which is caused by the regulation of the KA and/or KM currents.
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Affiliation(s)
- Ji-Woong Oh
- Department of Neurosurgery, Brain Research Group, Yonsei University Wonju College of Medicine, the Brain Research Group, Wonju, Republic of Korea
| | - Choong-Ku Lee
- Current address: Department of Molecular Neurobiology, Max-Planck Institute of Experimental Medicine, Gottingen, Germany.
| | - Kum Whang
- Department of Neurosurgery, Brain Research Group, Yonsei University Wonju College of Medicine, the Brain Research Group, Wonju, Republic of Korea.
| | - Seong-Woo Jeong
- Department of Physiology, Brain Research Group, Yonsei University Wonju College of Medicine, Wonju, Republic of Korea.
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Perry MD, Ng CA, Mangala MM, Ng TYM, Hines AD, Liang W, Xu MJO, Hill AP, Vandenberg JI. Pharmacological activation of IKr in models of long QT Type 2 risks overcorrection of repolarization. Cardiovasc Res 2021; 116:1434-1445. [PMID: 31628797 DOI: 10.1093/cvr/cvz247] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 08/21/2019] [Accepted: 10/09/2019] [Indexed: 12/11/2022] Open
Abstract
AIMS Current treatment for congenital long QT syndrome Type 2 (cLQTS2), an electrical disorder that increases the risk of life-threatening cardiac arrhythmias, is aimed at reducing the incidence of arrhythmia triggers (beta-blockers) or terminating the arrhythmia after onset (implantable cardioverter-defibrillator). An alternative strategy is to target the underlying disease mechanism, which is reduced rapid delayed rectifier current (IKr) passed by Kv11.1 channels. Small molecule activators of Kv11.1 have been identified but the extent to which these can restore normal cardiac signalling in cLQTS2 backgrounds remains unclear. Here, we examined the ability of ICA-105574, an activator of Kv11.1 that impairs transition to the inactivated state, to restore function to heterozygous Kv11.1 channels containing either inactivation enhanced (T618S, N633S) or expression deficient (A422T) mutations. METHODS AND RESULTS ICA-105574 effectively restored Kv11.1 current from heterozygous inactivation enhanced or expression defective mutant channels in heterologous expression systems. In a human-induced pluripotent stem cell-derived cardiomyocyte (hiPSC-CM) model of cLQTS2 containing the expression defective Kv11.1 mutant A422T, cardiac repolarization, estimated from the duration of calcium transients in isolated cells and the rate corrected field potential duration (FPDc) in culture monolayers of cells, was significantly prolonged. The Kv11.1 activator ICA-105574 was able to reverse the prolonged repolarization in a concentration-dependent manner. However, at higher doses, ICA-105574 produced a shortening of the FPDc compared to controls. In vitro and in silico analysis suggests that this overcorrection occurs as a result of a temporal redistribution of the peak IKr to much earlier in the plateau phase of the action potential, which results in early repolarization. CONCLUSION Kv11.1 activators, which target the primary disease mechanism, provide a possible treatment option for cLQTS2, with the caveat that there may be a risk of overcorrection that could itself be pro-arrhythmic.
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Affiliation(s)
- Matthew D Perry
- Victor Chang Cardiac Research Institute, 405 Liverpool Street, Darlinghurst, New South Wales 2010, Australia.,St Vincent's Clinical School, UNSW Sydney, New South Wales, Australia
| | - Chai-Ann Ng
- Victor Chang Cardiac Research Institute, 405 Liverpool Street, Darlinghurst, New South Wales 2010, Australia.,St Vincent's Clinical School, UNSW Sydney, New South Wales, Australia
| | - Melissa M Mangala
- Victor Chang Cardiac Research Institute, 405 Liverpool Street, Darlinghurst, New South Wales 2010, Australia
| | - Timothy Y M Ng
- Victor Chang Cardiac Research Institute, 405 Liverpool Street, Darlinghurst, New South Wales 2010, Australia.,St Vincent's Clinical School, UNSW Sydney, New South Wales, Australia
| | - Adam D Hines
- Victor Chang Cardiac Research Institute, 405 Liverpool Street, Darlinghurst, New South Wales 2010, Australia.,Queensland Brain Institute, The University of Queensland, St. Lucia 4072, Queensland, Australia
| | - Whitney Liang
- Victor Chang Cardiac Research Institute, 405 Liverpool Street, Darlinghurst, New South Wales 2010, Australia
| | - Michelle J O Xu
- Victor Chang Cardiac Research Institute, 405 Liverpool Street, Darlinghurst, New South Wales 2010, Australia.,St Vincent's Clinical School, UNSW Sydney, New South Wales, Australia
| | - Adam P Hill
- Victor Chang Cardiac Research Institute, 405 Liverpool Street, Darlinghurst, New South Wales 2010, Australia.,St Vincent's Clinical School, UNSW Sydney, New South Wales, Australia
| | - Jamie I Vandenberg
- Victor Chang Cardiac Research Institute, 405 Liverpool Street, Darlinghurst, New South Wales 2010, Australia.,St Vincent's Clinical School, UNSW Sydney, New South Wales, Australia
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Bushart DD, Zalon AJ, Zhang H, Morrison LM, Guan Y, Paulson HL, Shakkottai VG, McLoughlin HS. Antisense Oligonucleotide Therapy Targeted Against ATXN3 Improves Potassium Channel-Mediated Purkinje Neuron Dysfunction in Spinocerebellar Ataxia Type 3. Cerebellum 2021; 20:41-53. [PMID: 32789747 PMCID: PMC7930886 DOI: 10.1007/s12311-020-01179-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Spinocerebellar ataxia type 3 (SCA3) is the second-most common CAG repeat disease, caused by a glutamine-encoding expansion in the ATXN3 protein. SCA3 is characterized by spinocerebellar degeneration leading to progressive motor incoordination and early death. Previous studies suggest that potassium channel dysfunction underlies early abnormalities in cerebellar cortical Purkinje neuron firing in SCA3. However, cerebellar cortical degeneration is often modest both in the human disease and mouse models of SCA3, raising uncertainty about the role of cerebellar dysfunction in SCA3. Here, we address this question by investigating Purkinje neuron excitability in SCA3. In early-stage SCA3 mice, we confirm a previously identified increase in excitability of cerebellar Purkinje neurons and associate this excitability with reduced transcripts of two voltage-gated potassium (KV) channels, Kcna6 and Kcnc3, as well as motor impairment. Intracerebroventricular delivery of antisense oligonucleotides (ASO) to reduce mutant ATXN3 restores normal excitability to SCA3 Purkinje neurons and rescues transcript levels of Kcna6 and Kcnc3. Interestingly, while an even broader range of KV channel transcripts shows reduced levels in late-stage SCA3 mice, cerebellar Purkinje neuron physiology was not further altered despite continued worsening of motor impairment. These results suggest the progressive motor phenotype observed in SCA3 may not reflect ongoing changes in the cerebellar cortex but instead dysfunction of other neuronal structures within and beyond the cerebellum. Nevertheless, the early rescue of both KV channel expression and neuronal excitability by ASO treatment suggests that cerebellar cortical dysfunction contributes meaningfully to motor dysfunction in SCA3.
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Affiliation(s)
- David D. Bushart
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109
| | - Annie J. Zalon
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109
| | - Hongjiu Zhang
- Department of Computational Medicine & Bioinformatics, University of Michigan, Ann Arbor, MI 48109,Microsoft, Inc. Bellevue, WA 98004
| | - Logan M. Morrison
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109,Neuroscience Graduate Program, University of Michigan, Ann Arbor, MI 48109
| | - Yuanfang Guan
- Department of Computational Medicine & Bioinformatics, University of Michigan, Ann Arbor, MI 48109
| | - Henry L. Paulson
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109
| | - Vikram G. Shakkottai
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109,Department of Molecular & Integrative Physiology, University of Michigan, Ann Arbor, MI 48109,Address correspondence to: Vikram G. Shakkottai, 4009 BSRB, 109 Zina Pitcher Pl., Ann Arbor, MI 48109, ; Hayley S. McLoughlin, 4017 BSRB, 109 Zina Pitcher Pl., Ann Arbor, MI 48109,
| | - Hayley S. McLoughlin
- Department of Neurology, University of Michigan, Ann Arbor, MI 48109,Address correspondence to: Vikram G. Shakkottai, 4009 BSRB, 109 Zina Pitcher Pl., Ann Arbor, MI 48109, ; Hayley S. McLoughlin, 4017 BSRB, 109 Zina Pitcher Pl., Ann Arbor, MI 48109,
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Kohanski MA, Brown L, Orr M, Tan LH, Adappa ND, Palmer JN, Rubenstein RC, Cohen NA. Bitter taste receptor agonists regulate epithelial two-pore potassium channels via cAMP signaling. Respir Res 2021; 22:31. [PMID: 33509163 PMCID: PMC7844973 DOI: 10.1186/s12931-021-01631-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 01/20/2021] [Indexed: 11/20/2022] Open
Abstract
Background Epithelial solitary chemosensory cell (tuft cell) bitter taste signal transduction occurs through G protein coupled receptors and calcium-dependent signaling pathways. Type II taste cells, which utilize the same bitter taste signal transduction pathways, may also utilize cyclic adenosine monophosphate (cAMP) as an independent signaling messenger in addition to calcium. Methods In this work we utilized specific pharmacologic inhibitors to interrogate the short circuit current (Isc) of polarized nasal epithelial cells mounted in Ussing chambers to assess the electrophysiologic changes associated with bitter agonist (denatonium) treatment. We also assessed release of human β-defensin-2 from polarized nasal epithelial cultures following treatment with denatonium benzoate and/or potassium channel inhibitors. Results We demonstrate that the bitter taste receptor agonist, denatonium, decreases human respiratory epithelial two-pore potassium (K2P) current in polarized nasal epithelial cells mounted in Ussing chambers. Our data further suggest that this occurs via a cAMP-dependent signaling pathway. We also demonstrate that this decrease in potassium current lowers the threshold for denatonium to stimulate human β-defensin-2 release. Conclusions These data thus demonstrate that, in addition to taste transducing calcium-dependent signaling, bitter taste receptor agonists can also activate cAMP-dependent respiratory epithelial signaling pathways to modulate K2P currents. Bitter-agonist regulation of potassium currents may therefore serve as a means of rapid regional epithelial signaling, and further study of these pathways may provide new insights into regulation of mucosal ionic composition and innate mechanisms of epithelial defense.
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Affiliation(s)
- Michael A Kohanski
- Department of Otorhinolaryngology-Head and Neck Surgery, Division of Rhinology, University of Pennsylvania Medical Center, Perelman School of Medicine, 5th Floor Ravdin Building, 3400 Spruce Street, Philadelphia, PA, USA.
| | - Lauren Brown
- Cystic Fibrosis Center, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Melissa Orr
- Cystic Fibrosis Center, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Li Hui Tan
- Department of Otorhinolaryngology-Head and Neck Surgery, Division of Rhinology, University of Pennsylvania Medical Center, Perelman School of Medicine, 5th Floor Ravdin Building, 3400 Spruce Street, Philadelphia, PA, USA
| | - Nithin D Adappa
- Department of Otorhinolaryngology-Head and Neck Surgery, Division of Rhinology, University of Pennsylvania Medical Center, Perelman School of Medicine, 5th Floor Ravdin Building, 3400 Spruce Street, Philadelphia, PA, USA
| | - James N Palmer
- Department of Otorhinolaryngology-Head and Neck Surgery, Division of Rhinology, University of Pennsylvania Medical Center, Perelman School of Medicine, 5th Floor Ravdin Building, 3400 Spruce Street, Philadelphia, PA, USA
| | - Ronald C Rubenstein
- Cystic Fibrosis Center, The Children's Hospital of Philadelphia, Philadelphia, PA, USA.,Department of Pediatrics, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA.,Division of Allergy and Pulmonary Medicine, Department of Pediatrics, Washington University in St. Louis School of Medicine, St. Louis, MO, USA
| | - Noam A Cohen
- Department of Otorhinolaryngology-Head and Neck Surgery, Division of Rhinology, University of Pennsylvania Medical Center, Perelman School of Medicine, 5th Floor Ravdin Building, 3400 Spruce Street, Philadelphia, PA, USA.,Corporal Michael J. Crescenz Veterans Administration Medical Center, Philadelphia, PA, USA.,Monell Chemical Senses Institute, Philadelphia, PA, USA
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Abstract
Long QT syndrome (LQTS) is a cardiovascular disorder characterized by an abnormality in cardiac repolarization leading to a prolonged QT interval and T-wave irregularities on the surface electrocardiogram. It is commonly associated with syncope, seizures, susceptibility to torsades de pointes, and risk for sudden death. LQTS is a rare genetic disorder and a major preventable cause of sudden cardiac death in the young. The availability of therapy for this lethal disease emphasizes the importance of early and accurate diagnosis. Additionally, understanding of the molecular mechanisms underlying LQTS could help to optimize genotype-specific treatments to prevent deaths in LQTS patients. In this review, we briefly summarize current knowledge regarding molecular underpinning of LQTS, in particular focusing on LQT1, LQT2, and LQT3, and discuss novel strategies to study ion channel dysfunction and drug-specific therapies in LQT1, LQT2, and LQT3 syndromes.
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Affiliation(s)
| | - Isabelle Deschênes
- Department of Physiology and Cell Biology, The Ohio State University, Columbus, Ohio
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Krajewska M, Koprowski P. Solubilization, purification, and functional reconstitution of human ROMK potassium channel in copolymer styrene-maleic acid (SMA) nanodiscs. Biochim Biophys Acta Biomembr 2021; 1863:183555. [PMID: 33444624 DOI: 10.1016/j.bbamem.2021.183555] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Revised: 12/13/2020] [Accepted: 01/04/2021] [Indexed: 12/18/2022]
Abstract
Expression, purification, and functional reconstitution of mammalian ion channels are often challenging. Heterologous expression of mammalian channels in bacteria can be advantageous due to unrelated protein environment and the lack of risk of copurification of endogenous proteins, e.g., accessory channel subunits that can influence the channel activity. Also, direct recording of channel activity could be challenging due to their intracellular localization like in the case of mitochondrial channels. The activity of purified channels can be characterized at the single-molecule level by electrophysiological techniques, such as planar lipid bilayers (PLB). In this work, we describe a simple approach to accomplish PLB recording of the activity of single renal outer medullary potassium channels ROMK expressed in E. coli. We focused on the ROMK2 isoform that is present at low levels in the mitochondria and can be responsible for mitoKATP activity. We screened for the best construct to express the codon-optimized ROMK proteins with a 6xHis tag for protein purification. The strategy involved the use of optimal styrene-maleic acid (SMA) copolymer, which forms so-called polymer nanodiscs, to solubilize and purify ROMK-containing SMA lipid particles (SMALPs), which were amenable for fusion with PLB. Reconstituted ROMK channels exhibited ion selectivity, rectification, and pharmacological properties, which are in agreement with previous work on ROMK channels.
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Affiliation(s)
- Milena Krajewska
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology PAS, Pasteur str. 3, Warsaw 02-093, Poland
| | - Piotr Koprowski
- Laboratory of Intracellular Ion Channels, Nencki Institute of Experimental Biology PAS, Pasteur str. 3, Warsaw 02-093, Poland.
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Al-Moubarak E, Shiels HA, Zhang Y, Du C, Hanington O, Harmer SC, Dempsey CE, Hancox JC. Inhibition of the hERG potassium channel by phenanthrene: a polycyclic aromatic hydrocarbon pollutant. Cell Mol Life Sci 2021; 78:7899-914. [PMID: 34727194 DOI: 10.1007/s00018-021-03967-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 09/25/2021] [Accepted: 10/01/2021] [Indexed: 11/07/2022]
Abstract
The lipophilic polycyclic aromatic hydrocarbon (PAH) phenanthrene is relatively abundant in polluted air and water and can access and accumulate in human tissue. Phenanthrene has been reported to interact with cardiac ion channels in several fish species. This study was undertaken to investigate the ability of phenanthrene to interact with hERG (human Ether-à-go-go-Related Gene) encoded Kv11.1 K+ channels, which play a central role in human ventricular repolarization. Pharmacological inhibition of hERG can be proarrhythmic. Whole-cell patch clamp recordings of hERG current (IhERG) were made from HEK293 cells expressing wild-type (WT) and mutant hERG channels. WT IhERG1a was inhibited by phenanthrene with an IC50 of 17.6 ± 1.7 µM, whilst IhERG1a/1b exhibited an IC50 of 1.8 ± 0.3 µM. WT IhERG block showed marked voltage and time dependence, indicative of dependence of inhibition on channel gating. The inhibitory effect of phenanthrene was markedly impaired by the attenuated inactivation N588K mutation. Remarkably, mutations of S6 domain aromatic amino acids (Y652, F656) in the canonical drug binding site did not impair the inhibitory action of phenanthrene; the Y652A mutation augmented IhERG block. In contrast, the F557L (S5) and M651A (S6) mutations impaired the ability of phenanthrene to inhibit IhERG, as did the S624A mutation below the selectivity filter region. Computational docking using a cryo-EM derived hERG structure supported the mutagenesis data. Thus, phenanthrene acts as an inhibitor of the hERG K+ channel by directly interacting with the channel, binding to a distinct site in the channel pore domain.
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Fontaine JT, Rosehart AC, Joutel A, Dabertrand F. HB-EGF depolarizes hippocampal arterioles to restore myogenic tone in a genetic model of small vessel disease. Mech Ageing Dev 2020; 192:111389. [PMID: 33127441 PMCID: PMC7683376 DOI: 10.1016/j.mad.2020.111389] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 10/16/2020] [Accepted: 10/22/2020] [Indexed: 12/26/2022]
Abstract
Vascular cognitive impairment, the second most common cause of dementia, profoundly affects hippocampal-dependent functions. However, while the growing literature covers complex neuronal interactions, little is known about the sustaining hippocampal microcirculation. Here we examined vasoconstriction to physiological pressures of hippocampal arterioles, a fundamental feature of small arteries, in a genetic mouse model of CADASIL, an archetypal cerebral small vessel disease. Using diameter and membrane potential recordings on isolated arterioles, we observed both blunted pressure-induced vasoconstriction and smooth muscle cell depolarization in CADASIL. This impairment was abolished in the presence of voltage-gated potassium (KV1) channel blocker 4-aminopyridine, or by application of heparin-binding EGF-like growth factor (HB-EGF), which promotes KV1 channel down-regulations. Interestingly, we observed that HB-EGF induced a depolarization of the myocyte plasma membrane within the arteriolar wall in CADASIL, but not wild-type, arterioles. Collectively, our results indicate that hippocampal arterioles in CADASIL mice display a blunted contractile response to luminal pressure, similar to the defect we previously reported in cortical arterioles and pial arteries, that is rescued by HB-EGF. Hippocampal vascular dysfunction in CADASIL could then contribute to the decreased vascular reserve associated with decreased cognitive performance, and its correction may provide a therapeutic option for treating vascular cognitive impairment.
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Affiliation(s)
- Jackson T Fontaine
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Amanda C Rosehart
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA
| | - Anne Joutel
- Department of Pharmacology, Larner College of Medicine University of Vermont, Burlington, VT, USA; Institute of Psychiatry and Neurosciences of Paris, INSERM UMR1266, University of Paris, GHU Paris Psychiatrie et Neurosciences, France
| | - Fabrice Dabertrand
- Department of Anesthesiology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA; Department of Pharmacology, University of Colorado Anschutz Medical Campus, Aurora, CO, USA.
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Sun J, Liu Y, Baudry M, Bi X. SK2 channel regulation of neuronal excitability, synaptic transmission, and brain rhythmic activity in health and diseases. Biochim Biophys Acta Mol Cell Res 2020; 1867:118834. [PMID: 32860835 PMCID: PMC7541745 DOI: 10.1016/j.bbamcr.2020.118834] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 08/13/2020] [Accepted: 08/19/2020] [Indexed: 11/20/2022]
Abstract
Small conductance calcium-activated potassium channels (SKs) are solely activated by intracellular Ca2+ and their activation leads to potassium efflux, thereby repolarizing/hyperpolarizing membrane potential. Thus, these channels play a critical role in synaptic transmission, and consequently in information transmission along the neuronal circuits expressing them. SKs are widely but not homogeneously distributed in the central nervous system (CNS). Activation of SKs requires submicromolar cytoplasmic Ca2+ concentrations, which are reached following either Ca2+ release from intracellular Ca2+ stores or influx through Ca2+ permeable membrane channels. Both Ca2+ sensitivity and synaptic levels of SKs are regulated by protein kinases and phosphatases, and degradation pathways. SKs in turn control the activity of multiple Ca2+ channels. They are therefore critically involved in coordinating diverse Ca2+ signaling pathways and controlling Ca2+ signal amplitude and duration. This review highlights recent advances in our understanding of the regulation of SK2 channels and of their roles in normal brain functions, including synaptic plasticity, learning and memory, and rhythmic activities. It will also discuss how alterations in their expression and regulation might contribute to various brain disorders such as Angelman Syndrome, Alzheimer's disease and Parkinson's disease.
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Affiliation(s)
- Jiandong Sun
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA 91766, United States of America; Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766, United States of America
| | - Yan Liu
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA 91766, United States of America; Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766, United States of America
| | - Michel Baudry
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA 91766, United States of America; Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766, United States of America
| | - Xiaoning Bi
- College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA 91766, United States of America; Graduate College of Biomedical Sciences, Western University of Health Sciences, Pomona, CA 91766, United States of America.
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Bhatiya S, Choudhury S, Gari M, Singh P, Shukla A, Garg SK. Myometrial Calcium and Potassium Channels Play a Pivotal Role in Chromium-Induced Relaxation in Rat Uterus: an In Vitro Study. Biol Trace Elem Res 2020; 198:198-205. [PMID: 32034680 DOI: 10.1007/s12011-020-02041-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 01/07/2020] [Indexed: 11/25/2022]
Abstract
Hexavalent chromium, a well-known environmental toxicant, adversely affects female reproduction and results in abnormal implantation, fetal resorption, and reduction in litter size. Uterine myogenic activity is under control of number of receptors and ion channels, and it regulates fetal-implantation and feto-maternal communication. Despite several known adverse effects of chromium on female reproduction, direct action of chromium on myometrial activity is yet to be understood. In the present study, the effect of in vitro exposure of hexavalent chromium (Cr-VI) on the myogenic activity of isolated myometrial strips of rats was evaluated after mounting the tissue in thermostatically (37 ± 0.5 °C) controlled organ bath under a resting tension of 1 g. Chromium produced concentration-dependent (0.1 nM-0.1 mM) inhibitory effect on myometrial activity. Following pre-treatment of the myometrial strips with glibenclamide (a KATP channel blocker) and 4-aminopyridine (a Kv channel blocker), the concentration-response curve (CRC) of chromium was significantly (P < 0.05) shifted towards right with decrease in the maximum relaxant effect. Contractile effects of CaCl2 and BAY K-8644 (a selective opener of L-type Ca2+ channel) were significantly (P < 0.05) attenuated in the presence of chromium. Chromium-induced myometrial relaxation was also significantly (P < 0.05) reduced in the presence of ICI 118,551 (a selective β2-antagonist) and SR 59230A (a selective β3-antagonist). These findings evidently suggest that chromium produced relaxant effect on rat myometrium by interfering with Ca2+ entry through voltage-dependent Ca2+ channels, and by interacting with beta-adrenoceptors (β2 and β3) and potassium channels (especially KATP and Kv channels). Graphical Abstract Proposed signaling pathway(s) of chromium (VI)-induced myometrial relaxations in rats. KATP: ATP-sensitive K+ channel; KV: voltage-dependent K+ channel; VDCC: voltage-dependent Ca2+ channel; [Ca2+]i: intracellular calcium concentration, stimulatory mechanism, inhibitory mechanism.
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Affiliation(s)
- Shirish Bhatiya
- Smooth Muscle Pharmacology Laboratory, Department of Veterinary Pharmacology & Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya, Evam Go-Anusandhan Sansthan (DUVASU), Mathura, 281001, India
| | - Soumen Choudhury
- Smooth Muscle Pharmacology Laboratory, Department of Veterinary Pharmacology & Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya, Evam Go-Anusandhan Sansthan (DUVASU), Mathura, 281001, India
| | - Manju Gari
- Smooth Muscle Pharmacology Laboratory, Department of Veterinary Pharmacology & Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya, Evam Go-Anusandhan Sansthan (DUVASU), Mathura, 281001, India
| | - Pawan Singh
- Smooth Muscle Pharmacology Laboratory, Department of Veterinary Pharmacology & Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya, Evam Go-Anusandhan Sansthan (DUVASU), Mathura, 281001, India
| | - Amit Shukla
- Smooth Muscle Pharmacology Laboratory, Department of Veterinary Pharmacology & Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya, Evam Go-Anusandhan Sansthan (DUVASU), Mathura, 281001, India
| | - Satish Kumar Garg
- Smooth Muscle Pharmacology Laboratory, Department of Veterinary Pharmacology & Toxicology, College of Veterinary Science and Animal Husbandry, U.P. Pandit Deen Dayal Upadhyaya Pashu Chikitsa Vigyan Vishwavidyalaya, Evam Go-Anusandhan Sansthan (DUVASU), Mathura, 281001, India.
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Tian Y, Korn P, Tripathi P, Komnig D, Wiemuth D, Nikouee A, Classen A, Bolm C, Falkenburger BH, Lüscher B, Gründer S. The mono-ADP-ribosyltransferase ARTD10 regulates the voltage-gated K + channel Kv1.1 through protein kinase C delta. BMC Biol 2020; 18:143. [PMID: 33059680 PMCID: PMC7558731 DOI: 10.1186/s12915-020-00878-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 09/24/2020] [Indexed: 11/30/2022] Open
Abstract
Background ADP-ribosylation is a ubiquitous post-translational modification that involves both mono- and poly-ADP-ribosylation. ARTD10, also known as PARP10, mediates mono-ADP-ribosylation (MARylation) of substrate proteins. A previous screen identified protein kinase C delta (PKCδ) as a potential ARTD10 substrate, among several other kinases. The voltage-gated K+ channel Kv1.1 constitutes one of the dominant Kv channels in neurons of the central nervous system and the inactivation properties of Kv1.1 are modulated by PKC. In this study, we addressed the role of ARTD10-PKCδ as a regulator of Kv1.1. Results We found that ARTD10 inhibited PKCδ, which increased Kv1.1 current amplitude and the proportion of the inactivating current component in HeLa cells, indicating that ARTD10 regulates Kv1.1 in living cells. An inhibitor of ARTD10, OUL35, significantly decreased peak amplitude together with the proportion of the inactivating current component of Kv1.1-containing channels in primary hippocampal neurons, demonstrating that the ARTD10-PKCδ signaling cascade regulates native Kv1.1. Moreover, we show that the pharmacological blockade of ARTD10 increases excitability of hippocampal neurons. Conclusions Our results, for the first time, suggest that MARylation by ARTD10 controls neuronal excitability.
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Affiliation(s)
- Yuemin Tian
- Institute of Physiology, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany
| | - Patricia Korn
- Institute of Biochemistry and Molecular Biology, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany
| | - Priyanka Tripathi
- Institute of Physiology, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany.,Present address: Institute of Neuropathology, RWTH Aachen University Medical School, Pauwelsstrasse 30, 52074, Aachen, Germany
| | - Daniel Komnig
- Department of Neurology, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany.,JARA-Institute Molecular Neuroscience and Neuroimaging, Forschungszentrum Jülich, Jülich, Germany
| | - Dominik Wiemuth
- Institute of Physiology, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany
| | - Azadeh Nikouee
- Institute of Physiology, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany
| | - Arno Classen
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52056, Aachen, Germany
| | - Carsten Bolm
- Institute of Organic Chemistry, RWTH Aachen University, Landoltweg 1, 52056, Aachen, Germany
| | - Björn H Falkenburger
- Department of Neurology, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany.,JARA-Institute Molecular Neuroscience and Neuroimaging, Forschungszentrum Jülich, Jülich, Germany.,Present address: Department of Neurology, Dresden University Medical Center, Fetscherstraße 74, 01307, Dresden, Germany
| | - Bernhard Lüscher
- Institute of Biochemistry and Molecular Biology, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany
| | - Stefan Gründer
- Institute of Physiology, RWTH Aachen University, Pauwelsstrasse 30, 52074, Aachen, Germany.
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Fletcher-Taylor S, Thapa P, Sepela RJ, Kaakati R, Yarov-Yarovoy V, Sack JT, Cohen BE. Distinguishing Potassium Channel Resting State Conformations in Live Cells with Environment-Sensitive Fluorescence. ACS Chem Neurosci 2020; 11:2316-2326. [PMID: 32579336 DOI: 10.1021/acschemneuro.0c00276] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Ion channels are polymorphic membrane proteins whose high-resolution structures offer images of individual conformations, giving us starting points for identifying the complex and transient allosteric changes that give rise to channel physiology. Here, we report live-cell imaging of voltage-dependent structural changes of voltage-gated Kv2.1 channels using peptidyl tarantula toxins labeled with an environment-sensitive fluorophore, whose spectral shifts enable identification of voltage-dependent conformation changes in the resting voltage sensing domain (VSD) of the channel. We synthesize a new environment-sensitive, far-red fluorophore, julolidine phenoxazone (JP) azide, and conjugate it to tarantula toxin GxTX to characterize Kv2.1 VSD allostery during membrane depolarization. JP has an inherent response to the polarity of its immediate surroundings, offering site-specific structural insight into each channel conformation. Using voltage-clamp spectroscopy to collect emission spectra as a function of membrane potential, we find that they vary with toxin labeling site, the presence of Kv2 channels, and changes in membrane potential. With a high-affinity conjugate in which the fluorophore itself interacts closely with the channel, the emission shift midpoint is 50 mV more negative than the Kv2.1 gating current midpoint. This suggests that substantial conformational changes at the toxin-channel interface are associated with early gating charge transitions and these are not concerted with VSD motions at more depolarized potentials. These fluorescent probes enable study of conformational changes that can be correlated with electrophysiology, putting channel structures and models into a context of live-cell membranes and physiological states.
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Kortüm F, Niceta M, Magliozzi M, Dumic Kubat K, Robertson SP, Moresco A, Dentici ML, Baban A, Leoni C, Onesimo R, Obregon MG, Digilio MC, Zampino G, Novelli A, Tartaglia M, Kutsche K. Cantú syndrome versus Zimmermann-Laband syndrome: Report of nine individuals with ABCC9 variants. Eur J Med Genet 2020; 63:103996. [PMID: 32622958 DOI: 10.1016/j.ejmg.2020.103996] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 06/23/2020] [Accepted: 06/28/2020] [Indexed: 11/17/2022]
Abstract
Cantú syndrome (CS) is a rare developmental disorder characterized by a coarse facial appearance, macrocephaly, hypertrichosis, skeletal and cardiovascular anomalies and caused by heterozygous gain-of-function variants in ABCC9 and KCNJ8, encoding subunits of heterooctameric ATP-sensitive potassium (KATP) channels. CS shows considerable clinical overlap with Zimmermann-Laband syndrome (ZLS), a rare condition with coarse facial features, hypertrichosis, gingival overgrowth, intellectual disability of variable degree, and hypoplasia or aplasia of terminal phalanges and/or nails. ZLS is caused by heterozygous gain-of-function variants in KCNH1 or KCNN3, and gain-of-function KCNK4 variants underlie the clinically similar FHEIG (facial dysmorphism, hypertrichosis, epilepsy, intellectual disability/developmental delay, and gingival overgrowth) syndrome; KCNH1, KCNN3 and KCNK4 encode potassium channels. Within our research project on ZLS, we performed targeted Sanger sequencing of ABCC9 in 15 individuals tested negative for a mutation in the ZLS-associated genes and found two individuals harboring a heterozygous pathogenic ABCC9 missense variant. Through a collaborative effort, we identified a total of nine individuals carrying a monoallelic ABCC9 variant: five sporadic patients and four members of two unrelated families. Among the six detected ABCC9 missense variants, four [p.(Pro252Leu), p.(Thr259Lys), p.(Ala1064Pro), and p.(Arg1197His)] were novel. Systematic assessment of the clinical features in the nine cases with an ABCC9 variant highlights the significant clinical overlap between ZLS and CS that includes early developmental delay, hypertrichosis, gingival overgrowth, joint laxity, and hypoplasia of terminal phalanges and nails. Gain of K+ channel activity possibly accounts for significant clinical similarities of CS, ZLS and FHEIG syndrome and defines a new subgroup of potassium channelopathies.
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Affiliation(s)
- Fanny Kortüm
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Marcello Niceta
- Genetics and Rare Diseases Research Division, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Monia Magliozzi
- Genetics and Rare Diseases Research Division, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | | | - Stephen P Robertson
- Department of Women's and Children's Health, Dunedin School of Medicine, University of Otago, Dunedin, New Zealand
| | - Angelica Moresco
- Paediatric Hospital Dr. Juan P. Garrahan, Buenos Aires, Argentina
| | - Maria Lisa Dentici
- Genetics and Rare Diseases Research Division, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Anwar Baban
- The European Reference Network for Rare, Low Prevalence and Complex Diseases of the Heart - ERN GUARD-Heart, Pediatric Cardiology and Arrhythmia/Syncope Units, Bambino Gesù Children Hospital and Research Institute, Rome, Italy
| | - Chiara Leoni
- Center of Rare Diseases and Congenital Defects, Fondazione Policlinico Universitario A. Gemelli, IRCCS, Rome, Italy
| | - Roberta Onesimo
- Center of Rare Diseases and Congenital Defects, Fondazione Policlinico Universitario A. Gemelli, IRCCS, Rome, Italy
| | | | - Maria Cristina Digilio
- Genetics and Rare Diseases Research Division, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Giuseppe Zampino
- Center of Rare Diseases and Congenital Defects, Fondazione Policlinico Universitario A. Gemelli, IRCCS, Rome, Italy
| | - Antonio Novelli
- Genetics and Rare Diseases Research Division, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Marco Tartaglia
- Genetics and Rare Diseases Research Division, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy
| | - Kerstin Kutsche
- Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
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Amador-Muñoz D, Gutiérrez ÁM, Payán-Gómez C, Matheus LM. In silico and in vitro analysis of cation-activated potassium channels in human corneal endothelial cells. Exp Eye Res 2020; 197:108114. [PMID: 32561484 DOI: 10.1016/j.exer.2020.108114] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 06/02/2020] [Accepted: 06/07/2020] [Indexed: 12/31/2022]
Abstract
The corneal endothelium is the inner cell monolayer involved in the maintenance of corneal transparence by the generation of homeostatic dehydration. The glycosaminoglycans of the corneal stroma develop a continuous swelling pressure that should be counteracted by the corneal endothelial cells through active transport mechanisms to move the water to the anterior chamber. Protein transporters for sodium (Na+), potassium (K+), chloride (Cl-) and bicarbonate (HCO3-) are involved in this endothelial "pump function", however despite its physiological importance, the efflux mechanism is not completely understood. There is experimental evidence describing transendothelial diffusion of water in the absence of osmotic gradients. Therefore, it is important to get a deeper understanding of alternative models that drive the fluid transport across the endothelium such as the electrochemical gradients. Three transcriptomic datasets of the corneal endothelium were used in this study to analyze the expression of genes that encode proteins that participate in the transport and the reestablishment of the membrane potential across the semipermeable endothelium. Subsequently, the expression of the identified channels was validated in vitro both at mRNA and protein levels. The results of this study provide the first evidence of the expression of KCNN2, KCNN3 and KCNT2 genes in the corneal endothelium. Differences among the level of expression of KCNN2, KCNT2 and KCNN4 genes were found in a differentially expressed gene analysis of the dataset. Taken together these results underscore the potential importance of the ionic channels in the pathophysiology of corneal diseases. Moreover, we elucidate novel mechanisms that might be involved in the pivotal dehydrating function of the endothelium and in others physiologic functions of these cells using in silico pathways analysis.
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Affiliation(s)
- Diana Amador-Muñoz
- Neuroscience (NEUROS) Research Group, School of Medicine and Health Sciences, Universidad del Rosario, Carrera 24 No. 63 C 69, P.O 111221, Bogotá, Colombia.
| | - Ángela María Gutiérrez
- Escuela Superior de Oftalmología, Instituto Barraquer de América, Calle 100 No. 18 A 51, Bogotá, Colombia.
| | - César Payán-Gómez
- Department of Biology, Faculty of Natural Sciences, Universidad del Rosario, Carrera 24 No. 63 C 69, Bogotá, P.O 111221, Colombia.
| | - Luisa Marina Matheus
- Neuroscience (NEUROS) Research Group, School of Medicine and Health Sciences, Universidad del Rosario, Carrera 24 No. 63 C 69, P.O 111221, Bogotá, Colombia.
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Zhu W, Gao H, Luo X, Ye X, Ding L, Hao J, Shu Z, Li S, Li J, Chen Z. Cloning and identification of a new multifunctional Ascaris-type peptide from the hemolymph of Buthus martensii Karsch. Toxicon 2020; 184:167-174. [PMID: 32565098 DOI: 10.1016/j.toxicon.2020.06.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 06/10/2020] [Accepted: 06/15/2020] [Indexed: 10/24/2022]
Abstract
Only a few work have been done for peptides from non-venom gland tissues of venomous animals. Here, with the help of the whole body transcriptomic and the hemolymph proteomic data of the Chinese scorpion Buthus martensii Karsch, we identified the first Ascaris-type peptide BmHDP from scorpion hemolymph. The precursor of BmHDP has 80 residues, including a 16 residue signal peptide and a 64 residue mature peptide. The mature peptide has 10 conserved cysteines and adopts a conserved Ascaris-type fold. Using combined inclusion body refolding and biochemical identification strategies, recombinant BmHDP was obtained successfully. Protease inhibitory assays showed that BmHDP inhibited chymotrypsin apparently at a concentration of 8 nM. Patch-clamp experiments showed that BmHDP inhibited the Kv1.3 potassium channel apparently at a concentration of 1000 nM. Coagulation experiment assays showed that BmHDP inhibited intrinsic coagulation pathway apparently at a concentration of 500 nM. To the best of our knowledge, BmHDP is the first Ascaris-type peptide from scorpion hemolymph. Our work highlighted a functional link between scorpion non-venom gland peptides and venom gland toxin peptides, and suggested that scorpion hemolymph might be a new source of bioactive peptides.
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Affiliation(s)
- Wen Zhu
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, College of Basic Medicine, Hubei University of Medicine, Hubei, China
| | - Huanhuan Gao
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, College of Basic Medicine, Hubei University of Medicine, Hubei, China
| | - Xudong Luo
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, College of Basic Medicine, Hubei University of Medicine, Hubei, China; Institute of Biomedicine and Hubei Key Laboratory of Wudang Local Chinese Medicine Research, Hubei University of Medicine, Hubei, China
| | - Xiangdong Ye
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, College of Basic Medicine, Hubei University of Medicine, Hubei, China; Institute of Biomedicine and Hubei Key Laboratory of Wudang Local Chinese Medicine Research, Hubei University of Medicine, Hubei, China
| | - Li Ding
- Department of Clinical Laboratory, Dongfeng Hospital, Hubei University of Medicine, Hubei, China; Institute of Biomedicine and Hubei Key Laboratory of Wudang Local Chinese Medicine Research, Hubei University of Medicine, Hubei, China
| | - Jinbo Hao
- Department of Clinical Laboratory, Shiyan Occupational Disease Hospital, Hubei, China
| | - Zhan Shu
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, College of Basic Medicine, Hubei University of Medicine, Hubei, China
| | - Shan Li
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, College of Basic Medicine, Hubei University of Medicine, Hubei, China
| | - Jian Li
- Department of Human Parasitology, College of Basic Medical Sciences, Hubei University of Medicine, Hubei, China
| | - Zongyun Chen
- Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, College of Basic Medicine, Hubei University of Medicine, Hubei, China; Institute of Biomedicine and Hubei Key Laboratory of Wudang Local Chinese Medicine Research, Hubei University of Medicine, Hubei, China.
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72
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Harrigan J, Brambila DF, Meera P, Krantz DE, Schweizer FE. The environmental toxicant ziram enhances neurotransmitter release and increases neuronal excitability via the EAG family of potassium channels. Neurobiol Dis 2020; 143:104977. [PMID: 32553709 DOI: 10.1016/j.nbd.2020.104977] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2020] [Revised: 06/11/2020] [Accepted: 06/13/2020] [Indexed: 12/21/2022] Open
Abstract
Environmental toxicants have the potential to contribute to the pathophysiology of multiple complex diseases, but the underlying mechanisms remain obscure. One such toxicant is the widely used fungicide ziram, a dithiocarbamate known to have neurotoxic effects and to increase the risk of Parkinson's disease. We have used Drosophila melanogaster as an unbiased discovery tool to identify novel molecular pathways by which ziram may disrupt neuronal function. Consistent with previous results in mammalian cells, we find that ziram increases the probability of synaptic vesicle release by dysregulation of the ubiquitin signaling system. In addition, we find that ziram increases neuronal excitability. Using a combination of live imaging and electrophysiology, we find that ziram increases excitability in both aminergic and glutamatergic neurons. This increased excitability is phenocopied and occluded by null mutant animals of the ether a-go-go (eag) potassium channel. A pharmacological inhibitor of the temperature sensitive hERG (human ether-a-go-go related gene) phenocopies the excitability effects of ziram but only at elevated temperatures. seizure (sei), a fly ortholog of hERG, is thus another candidate target of ziram. Taken together, the eag family of potassium channels emerges as a candidate for mediating some of the toxic effects of ziram. We propose that ziram may contribute to the risk of complex human diseases by blockade of human eag and sei orthologs, such as hERG.
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73
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Marques AAM, da Silva CHF, de Souza P, de Almeida CLB, Cechinel-Filho V, Lourenço ELB, Gasparotto Junior A. Nitric oxide and Ca 2+-activated high-conductance K + channels mediate nothofagin-induced endothelium-dependent vasodilation in the perfused rat kidney. Chem Biol Interact 2020; 327:109182. [PMID: 32554038 DOI: 10.1016/j.cbi.2020.109182] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 05/26/2020] [Accepted: 06/15/2020] [Indexed: 02/08/2023]
Abstract
Nothofagin is a natural 3'-C-β-D-glucoside of the polyphenol phloretin that is mainly found in Aspalathus linearis, Nothofagus fusca, and Leandra dasytricha. In recent years, nothofagin has been described as a potential therapeutic agent for renal disorders, but the mechanisms that are involved in its renoprotective effects remain unclear. In the present study, perfused rat kidneys were used to test the hypothesis that nothofagin causes the direct relaxation of renal arteries. The molecular mechanisms that underlie these vascular effects were also investigated. The left kidney from Wistar rats was coupled in a perfusion system and continuously perfused with physiological saline solution (PSS). Initially, preparations with and without the endothelium were contracted with phenylephrine and received injections of 1-300 nmol nothofagin. The preparations were then perfused with PSS that contained phenylephrine plus KCl, indomethacin, l-NAME, tetraethylammonium, glibenclamide, 4-aminopyridine, iberiotoxin, charybdotoxin, and apamin. After 15 min under perfusion, nothofagin was injected again. In preparations with an intact endothelium, nothofagin dose-dependently reduced perfusion pressure. Endothelium removal or the inhibition of nitric oxide synthase by l-NAME prevented the vasodilatory effect of nothofagin at all doses tested. Perfusion with PSS that contained KCl or tetraethylammonium chloride also abolished the vasodilatory effect of nothofagin. Treatment with glibenclamide, 4-aminopyridine, and apamin did not affect the vasodilatory effect of nothofagin. Iberiotoxin (selective Ca2+-activated high-conductance K+ channel [KCa1.1] blocker) and charybdotoxin (selective KCa1.1 and Ca2+-activated intermediate-conductance K+ channel [KCa3.1] blocker) application blocked the vasodilatory effect of nothofagin at all doses tested, pointing to a predominant role for KCa1.1 in the action of nothofagin. However, these data cannot exclude a potential contribution of endothelial KCa3.1 channel in the nothofagin-induced vasodilation. Overall, our findings indicate that nothofagin induces vasodilation in renal arteries, an effect that is mediated by Ca2+ -activated high-conductance K+ channels opening and endothelial nitric oxide production.
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Affiliation(s)
- Aline Aparecida Macedo Marques
- Laboratory of Electrophysiology and Cardiovascular Pharmacology, Faculty of Health Sciences, Universidade Federal da Grande Dourados, Dourados, MS, Brazil
| | | | - Priscila de Souza
- Graduate Program in Pharmaceutical Sciences, Nucleus of Chemical-Pharmaceutical Investigations (NIQFAR), University of Vale do Itajaí, Itajaí, SC, Brazil
| | - Camila L B de Almeida
- Graduate Program in Pharmaceutical Sciences, Nucleus of Chemical-Pharmaceutical Investigations (NIQFAR), University of Vale do Itajaí, Itajaí, SC, Brazil
| | - Valdir Cechinel-Filho
- Graduate Program in Pharmaceutical Sciences, Nucleus of Chemical-Pharmaceutical Investigations (NIQFAR), University of Vale do Itajaí, Itajaí, SC, Brazil
| | - Emerson L B Lourenço
- Laboratory of Preclinical Research of Natural Products, Paranaense University, Umuarama, PR, Brazil
| | - Arquimedes Gasparotto Junior
- Laboratory of Electrophysiology and Cardiovascular Pharmacology, Faculty of Health Sciences, Universidade Federal da Grande Dourados, Dourados, MS, Brazil.
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Abdel-Gaber SA, Atta M, Abdel-Hafez SMN, Abdelzaher WY. Ameliorative effect of nicorandil in ovarian ischemia-reperfusion-induced injury in rats: role of potassium channel. Naunyn Schmiedebergs Arch Pharmacol 2020; 393:1599-610. [PMID: 32266443 DOI: 10.1007/s00210-020-01854-w] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 03/12/2020] [Indexed: 12/14/2022]
Abstract
Ovarian torsion is a gynecological emergency that leads to serious outcomes. Nicorandil (NIC) is an ATP-sensitive potassium (KATP) channel activator that protects the heart from ischemia. The current study aimed to investigate the role and mechanism of action of NIC in ovarian ischemia-reperfusion (OIR) and possible KATP participation. Twenty-four female albino rats were classified into 4 groups: sham control, OIR, OIR + NIC, OIR + NIC+ glibenclamide (GLB) groups. Serum anti-Müllerian hormone (AMH), ovarian malondialdehyde (MDA), total nitrites (NOx) contents, and superoxide dismutase (SOD) activity were evaluated. Bax and Bcl2 mRNA were also assessed. Histological and immunohistochemical (anti-COX-2 and anti CD68) studies were done. The OIR non-treated group showed histopathological ovarian injury with decreased AMH level. Ovarian MDA, NOx, and Bax mRNA and the expression of COX-2 and CD68 were increased; however, SOD activity and Bcl2 mRNA level were decreased by OIR. NIC significantly ameliorated the histopathological ovarian injury with the restoration of AMH level. NIC significantly corrected oxidative stress and apoptotic biomarkers with decreased COX-2 and CD68 immunostaining. GLB co-administration significantly decreased the protection afforded by NIC. These results imply that NIC has a protective role against OIR via antioxidant, anti-inflammatory, and anti-apoptotic effects and such protection relies, at least partially, on the KATP channel.
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75
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Uchino T, Zheng MQ, Wang Y, Ono K. Cardiac specific transcription factor Csx/Nkx2.5 regulates transient-outward K + channel expression in pluripotent P19 cell-derived cardiomyocytes. J Physiol Sci 2020; 70:20. [PMID: 32213161 PMCID: PMC7096375 DOI: 10.1186/s12576-020-00748-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 03/12/2020] [Indexed: 01/31/2023]
Abstract
The homeobox-containing gene Csx/Nkx2.5 codes several cardiac transcription factors and plays a critical role in early cardiogenesis. We investigated the effect of Csx/Nkx2.5 on the expression of cardiac ion channels using P19-derived cardiomyocytes. P19CL6 cells and P19CL6 cells with Csx/Nkx2.5 overexpression (P19CL6-Csx cells) were induced to differentiate into cardiomyocytes by treatment with dimethyl sulfoxide. Action potentials and membrane currents were measured by whole cell patch clamp at different differentiation stage: the early stage (1–5 days after beating had begun) and the late stage (10–15 days after beating). Expression of Csx/Nkx2.5 mRNA was increased as the differentiation stages advanced in both P19CL6 and P19CL6-Csx cells. In action potential configuration, maximal diastolic potentials in P19CL6-Csx cells exhibited more hyperpolarized potential (‒ 64.2 mV) than those in P19CL6 cells (‒ 54.8 mV, p < 0.01) in the early stage. In P19CL6 cells, among 6 different voltage-gated and ligand-operated K+ channels expressed during the early stage, the transient-outward K+ channel was most predominant. By overexpression of Csx/Nkx2.5, developmental decrease in the transient-outward K+ channel was suppressed. Homeobox-containing gene Csx/Nkx2.5 modifies the amount of distinct ionic channels, during differentiation periods, predominantly changing the expression of the transient-outward K+ channel.
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Affiliation(s)
- Tomoko Uchino
- Department of Pathophysiology, Oita University School of Medicine, Oita, Japan.,Department of Anesthesiology, Oita University School of Medicine, Oita, Japan
| | - Ming-Qi Zheng
- Department of Pathophysiology, Oita University School of Medicine, Oita, Japan.,Department of Cardiovascular Medicine, Hebei Medical University, Shijiazhuang, Hebei, China
| | - Yan Wang
- Department of Pathophysiology, Oita University School of Medicine, Oita, Japan
| | - Katsushige Ono
- Department of Pathophysiology, Oita University School of Medicine, Oita, Japan.
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76
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Khandelwal P, Sabanadesan J, Sinha A, Hari P, Bagga A. Isolated nephrocalcinosis due to compound heterozygous mutations in renal outer medullary potassium channel. CEN Case Rep 2020; 9:232-236. [PMID: 32185747 DOI: 10.1007/s13730-020-00464-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 03/03/2020] [Indexed: 02/06/2023] Open
Abstract
Identification of a monogenic etiology is possible in a proportion of patients with childhood-onset nephrolithiasis or nephrocalcinosis. Bartter syndrome (BS), a hereditary tubulopathy characterized by polyuria, hypokalemic alkalosis and growth retardation that rarely presents with isolated nephrocalcinosis. Patients with defect in renal outer medullary potassium channel, encoded by the KCNJ1 gene causing BS type 2, typically present during the neonatal period. We describe a 14-year-old girl with mild late-onset BS type 2 with reported pathogenic compound heterozygous variations in exon 2 of KCNJ1 (c.146G > A and c.657C > G). This patient presented with isolated medullary nephrocalcinosis due to hypercalciuria; absence of hypokalemia and metabolic alkalosis was unique. This case highlights the importance of screening the KCNJ1 gene in patients with hypercalciuria and nephrocalcinosis, even in older children.
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Affiliation(s)
- Priyanka Khandelwal
- Division of Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110029, India
| | - Jasintha Sabanadesan
- Division of Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110029, India
| | - Aditi Sinha
- Division of Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110029, India
| | - Pankaj Hari
- Division of Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110029, India
| | - Arvind Bagga
- Division of Nephrology, Department of Pediatrics, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, 110029, India.
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77
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Han L, Song N, Hu X, Zhu A, Wei X, Liu J, Yuan S, Mao W, Chen X. Inhibition of RELM-β prevents hypoxia-induced overproliferation of human pulmonary artery smooth muscle cells by reversing PLC-mediated KCNK3 decline. Life Sci 2020; 246:117419. [PMID: 32045592 DOI: 10.1016/j.lfs.2020.117419] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Revised: 01/29/2020] [Accepted: 02/07/2020] [Indexed: 02/09/2023]
Abstract
AIMS Although resistin-like molecule β (RELM-β) is involved in the pathological processes of various lung diseases, such as pulmonary inflammation, asthma and fibrosis, its potential roles in hypoxic pulmonary arterial hypertension (PAH) remain largely unknown. The study aims to investigate whether RELM-β contributes to hypoxia-induced excessive proliferation of human pulmonary artery smooth muscle cells (PASMCs) and to explore the potential mechanisms of this process. MAIN METHODS Human PASMCs were exposed to normoxia or hypoxia (1% O2) for 24 h. siRNA targeting RELM-β was transfected into cells. Protein levels of KCNK3, RELM-β, pSTAT3 and STAT3 were determined by immunoblotting. The translocation of NFATc2 and expression of KCNK3 were visualized by immunofluorescence. 5-ethynyl-2'-deoxyuridine assays and cell counting kit-8 assays were performed to assess the proliferation of PASMCs. KEY FINDINGS (1) Chronic hypoxia significantly decreased KCNK3 protein levels while upregulating RELM-β protein levels in human PASMCs, which was accompanied by excessive proliferation of cells. (2) RELM-β could promote human PASMCs proliferation and activate the STAT3/NFAT axis by downregulating KCNK3 protein under normoxia. (3) Inhibition of RELM-β expression effectively prevented KCNK3-mediated cell proliferation under hypoxia. (4) Phospholipase C (PLC) inhibitor U-73122 could not only prevent the hypoxia/RELM-β-induced decrease in KCNK3 protein, but also inhibit the enhanced cell viability caused by hypoxia/RELM-β. (5) Both hypoxia and RELM-β could downregulate membrane KCNK3 protein levels by enhancing endocytosis. SIGNIFICANCE RELM-β activation is responsible for hypoxia-induced excessive proliferation of human PASMCs. Interfering with RELM-β may alleviate the progression of hypoxic PAH by upregulating PLC-dependent KCNK3 expression.
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Affiliation(s)
- Linlin Han
- Department of Anesthesiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Nannan Song
- Department of Anesthesiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Xiaomin Hu
- Department of Anesthesiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Afang Zhu
- Department of Anesthesiology, Peking Union Medical College Hospital, CAMS&PUMC, Beijing, China
| | - Xin Wei
- Department of Anesthesiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Jinmin Liu
- Department of Anesthesiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Shiying Yuan
- Department of Anesthesiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Weike Mao
- Department of Anesthesiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
| | - Xiangdong Chen
- Department of Anesthesiology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China.
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Lissabet JFB, Belén LH, Farias JG. PPLK +C: A Bioinformatics Tool for Predicting Peptide Ligands of Potassium Channels Based on Primary Structure Information. Interdiscip Sci 2020; 12:258-263. [PMID: 31912313 DOI: 10.1007/s12539-019-00356-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 12/22/2019] [Accepted: 12/24/2019] [Indexed: 10/25/2022]
Abstract
Potassium channels play a key role in regulating the flow of ions through the plasma membrane, orchestrating many cellular processes including cell volume regulation, hormone secretion and electrical impulse formation. Ligand peptides of potassium channels are molecules used in basic and applied research and are now considered promising alternatives in the treatment of many diseases, such as cardiovascular diseases and cancer. Currently, there are various bioinformatics tools focused on the prediction of peptides with different activities. However, none of the current tools can predict ligand peptides of potassium channels. In this work, we developed a tool called PPLK+C; this is the first tool that can predict peptide ligands of potassium channels. We also evaluated several amino acid molecular features and four machine-learning algorithms for the prediction of potassium channel ligand peptides: random forest, nearest neighbors, support vector machine and artificial neural network. All the biological data used in this study for training and validating models were obtained from peptides with experimentally verified activity. PPLK+C is a bioinformatics software written in the Python programming language, which showed a high predictive capacity with a model generated with the random forest algorithm: 0.77 sensitivity, 0.94 specificity, 0.91 accuracy and 0.70 Matthews correlation coefficient. PPLK+C is a novel tool with a friendly interface that can be used for the discovery of novel ligand peptides of potassium channels with high reliability, using only primary structure information.
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Affiliation(s)
- Jorge Félix Beltrán Lissabet
- Department of Chemical Engineering, Faculty of Engineering and Sciences, Universidad de La Frontera, Av. Francisco Salazar 01145, P.O. Box 54-D, 4811230, Temuco, Chile
| | - Lisandra Herrera Belén
- Department of Chemical Engineering, Faculty of Engineering and Sciences, Universidad de La Frontera, Av. Francisco Salazar 01145, P.O. Box 54-D, 4811230, Temuco, Chile
| | - Jorge G Farias
- Department of Chemical Engineering, Faculty of Engineering and Sciences, Universidad de La Frontera, Av. Francisco Salazar 01145, P.O. Box 54-D, 4811230, Temuco, Chile.
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Kim SE, Yin MZ, Kim HJ, Vorn R, Yoo HY, Kim SJ. Decreased inward rectifier and voltage-gated K + currents of the right septal coronary artery smooth muscle cells in pulmonary arterial hypertensive rats. Korean J Physiol Pharmacol 2020; 24:111-119. [PMID: 31908580 PMCID: PMC6940494 DOI: 10.4196/kjpp.2020.24.1.111] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 11/28/2019] [Accepted: 11/28/2019] [Indexed: 11/15/2022]
Abstract
In vascular smooth muscle, K+ channels, such as voltage-gated K+ channels (Kv), inward-rectifier K+ channels (Kir), and big-conductance Ca2+-activated K+ channels (BKCa), establish a hyperpolarized membrane potential and counterbalance the depolarizing vasoactive stimuli. Additionally, Kir mediates endothelium-dependent hyperpolarization and the active hyperemia response in various vessels, including the coronary artery. Pulmonary arterial hypertension (PAH) induces right ventricular hypertrophy (RVH), thereby elevating the risk of ischemia and right heart failure. Here, using the whole-cell patch-clamp technique, we compared Kv and Kir current densities (IKv and IKir) in the left (LCSMCs), right (RCSMCs), and septal branches of coronary smooth muscle cells (SCSMCs) from control and monocrotaline (MCT)-induced PAH rats exhibiting RVH. In control rats, (1) IKv was larger in RCSMCs than that in SCSMCs and LCSMCs, (2) IKv inactivation occurred at more negative voltages in SCSMCs than those in RCSMCs and LCSMCs, (3) IKir was smaller in SCSMCs than that in RCSMCs and LCSMCs, and (4) IBKCa did not differ between branches. Moreover, in PAH rats, IKir and IKv decreased in SCSMCs, but not in RCSMCs or LCSMCs, and IBKCa did not change in any of the branches. These results demonstrated that SCSMC-specific decreases in IKv and IKir occur in an MCT-induced PAH model, thereby offering insights into the potential pathophysiological implications of coronary blood flow regulation in right heart disease. Furthermore, the relatively smaller IKir in SCSMCs suggested a less effective vasodilatory response in the septal region to the moderate increase in extracellular K+ concentration under increased activity of the myocardium.
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Affiliation(s)
- Sung Eun Kim
- Department of Physiology, Seoul National University College of Medicine, Seoul 03080, Korea.,Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul 03080, Korea
| | - Ming Zhe Yin
- Department of Physiology, Seoul National University College of Medicine, Seoul 03080, Korea.,Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul 03080, Korea
| | - Hae Jin Kim
- Department of Physiology, Seoul National University College of Medicine, Seoul 03080, Korea.,Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul 03080, Korea
| | - Rany Vorn
- Department of Nursing, Chung-Ang University, Seoul 06974, Korea
| | - Hae Young Yoo
- Department of Nursing, Chung-Ang University, Seoul 06974, Korea
| | - Sung Joon Kim
- Department of Physiology, Seoul National University College of Medicine, Seoul 03080, Korea.,Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul 03080, Korea.,Ischemic/Hypoxic Disease Institute, Seoul National University College of Medicine, Seoul 03080, Korea
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80
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Shmukler BE, Rivera A, Bhargava P, Nishimura K, Hsu A, Kim EH, Trudel M, Rust MB, Hubner CA, Brugnara C, Alper SL. Combined genetic disruption of K-Cl cotransporters and Gardos channel KCNN4 rescues erythrocyte dehydration in the SAD mouse model of sickle cell disease. Blood Cells Mol Dis 2019; 79:102346. [PMID: 31352162 PMCID: PMC6744291 DOI: 10.1016/j.bcmd.2019.102346] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 07/09/2019] [Accepted: 07/09/2019] [Indexed: 10/26/2022]
Abstract
Excessive red cell dehydration contributes to the pathophysiology of sickle cell disease (SCD). The densest fraction of sickle red cells (with the highest corpuscular hemoglobin concentration) undergoes the most rapid polymerization of deoxy-hemoglobin S, leading to accelerated cell sickling and increased susceptibility to endothelial activation, red cell adhesion, and vaso-occlusion. Increasing red cell volume in order to decrease red cell density can thus serve as an adjunct therapeutic goal in SCD. Regulation of circulating mouse red cell volume and density is mediated largely by the Gardos channel, KCNN4, and the K-Cl cotransporters, KCC3 and KCC1. Whereas inhibition of the Gardos channel in subjects with sickle cell disease increased red cell volume, decreased red cell density, and improved other hematological indices in subjects with SCD, specific KCC inhibitors have not been available for testing. We therefore investigated the effect of genetic inactivation of KCC3 and KCC1 in the SAD mouse model of sickle red cell dehydration, finding decreased red cell density and improved hematological indices. We describe here generation of mice genetically deficient in the three major red cell volume regulatory gene products, KCNN4, KCC3, and KCC1 in C57BL6 non-sickle and SAD sickle backgrounds. We show that combined loss-of-function of all three gene products in SAD mice leads to incrementally increased MCV, decreased CHCM and % hyperchromic cells, decreased red cell density (phthalate method), increased resistance to hypo-osmotic lysis, and increased cell K content. The data show that combined genetic deletion of the Gardos channel and K-Cl cotransporters in a mouse SCD model decreases red cell density and improves several hematological parameters, supporting the strategy of combined pharmacological inhibition of these ion transport pathways in the adjunct treatment of human SCD.
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Affiliation(s)
- Boris E Shmukler
- Renal Division and Vascular Biology Research Center, Beth Israel Deaconess Medical Center, Boston, MA, United States of America; Department of Laboratory Medicine, Boston Children's Hospital, Boston, MA 02115, United States of America
| | - Alicia Rivera
- Renal Division and Vascular Biology Research Center, Beth Israel Deaconess Medical Center, Boston, MA, United States of America; Department of Medicine, Harvard Medical School, Boston, MA 02115, United States of America; Department of Pathology, Harvard Medical School, Boston, MA 02115, United States of America
| | - Parul Bhargava
- Department of Laboratory Medicine, UCSF, San Francisco, CA, United States of America
| | - Katherine Nishimura
- Renal Division and Vascular Biology Research Center, Beth Israel Deaconess Medical Center, Boston, MA, United States of America
| | - Ann Hsu
- Renal Division and Vascular Biology Research Center, Beth Israel Deaconess Medical Center, Boston, MA, United States of America
| | - Edward H Kim
- Renal Division and Vascular Biology Research Center, Beth Israel Deaconess Medical Center, Boston, MA, United States of America
| | - Marie Trudel
- Institut de Recherches Cliniques de Montreal, Molecular Genetics and Development, Faculte de Medecine, Universite of Montreal, Montreal, Quebec, Canada
| | - Marco B Rust
- Institute of Physiological Chemistry, Philipps-Universität Marburg, Marburg, Germany
| | | | - Carlo Brugnara
- Department of Laboratory Medicine, Boston Children's Hospital, Boston, MA 02115, United States of America; Department of Pathology, Harvard Medical School, Boston, MA 02115, United States of America
| | - Seth L Alper
- Renal Division and Vascular Biology Research Center, Beth Israel Deaconess Medical Center, Boston, MA, United States of America; Department of Medicine, Harvard Medical School, Boston, MA 02115, United States of America.
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Lu J, Liu H, Lin S, Li C, Wu H. Electrophysiological characterization of acutely isolated spiral ganglion neurons in neonatal and mature sonic hedgehog knock-in mice. Neurosci Lett 2019; 714:134536. [PMID: 31589904 DOI: 10.1016/j.neulet.2019.134536] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 09/04/2019] [Accepted: 10/01/2019] [Indexed: 12/18/2022]
Abstract
Spiral ganglion neurons (SGNs) are primary afferent auditory neurons activated by inner hair cells in mammalian cochlea. Here, for the convenience of SGN studies such as patch-clamp or single cell RNA-sequence studies, a knock-in mouse (ShhCreEGFP/+; Rosa26-Tdtomatoloxp/+) was generated for the purpose of obtaining fluorescence SGNs. Auditory brainstem response (ABR) and Tuj1 immunohistochemistry staining were performed to verify the hearing function and the morphological characteristics. The results showed that there was no significant difference between shh and wild type mice. In electrophysiological studies, we verified a series of electrophysiological characteristics including the amplitude of sodium and potassium currents and action potential characteristics of shh and wild type mice and no significant differences were found either. From the above, shh mice have the same cell function and morphology as their littermate control wild type mice and could be used as an ideal tool to study the function and characteristics of spiral ganglion neurons. Potassium channels of SGNs play an important role in resolving time accuracy. We obtained similar amplitude of IK+ in neonatal and mature mice in the aging competition experiment, however, the density of IK+ from mature mice were significantly different from those of neonatal mice, a phenomenon that may play a key role in the nervous system. Potassium channels have been shown to contribute to apoptosis induced by cisplatin administration in various cell lines. Here we used cisplatin administration to study the ototoxicity and found that the effects of a low dose of cisplatin (0.5 mM correspond to therapeutic doses) causes a decrease in currents and is reversible after a short administration time. Moreover, we propose the activated state of potassium channels has changed but the characteristic and number remain still after cisplatin administration. The excess potassium ions may accumulate in the cell body, which had affected the firing properties and induce cytotoxicity and apoptosis. We suggest that the electrophysiological properties of acutely isolated SGNs may support further research on the mechanics of auditory propagation and ion channel pharmacology.
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Affiliation(s)
- Jiawen Lu
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Huihui Liu
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China
| | - Shanshan Lin
- College of Medical Technology, Zhejiang Chinese Medical University, Hangzhou, China
| | - Chao Li
- Institute of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai Institutes for Biological Sciences, China
| | - Hao Wu
- Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Ear Institute, Shanghai Jiao Tong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Translational Medicine on Ear and Nose Diseases, Shanghai, China.
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82
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Kamatham S, Waters CM, Schwingshackl A, Mancarella S. TREK-1 protects the heart against ischemia-reperfusion-induced injury and from adverse remodeling after myocardial infarction. Pflugers Arch 2019; 471:1263-1272. [PMID: 31511966 DOI: 10.1007/s00424-019-02306-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 08/12/2019] [Accepted: 08/22/2019] [Indexed: 11/28/2022]
Abstract
The TWIK-related K+ channel (TREK-1) is a two-pore-domain potassium channel that produces background leaky potassium currents. TREK-1 has a protective role against ischemia-induced neuronal damage. TREK-1 is also expressed in the heart, but its role in myocardial ischemia-reperfusion (IR)-induced injury has not been examined. In the current study, we used a TREK-1 knockout (KO) mouse model to show that TREK-1 has a critical role in the cardiac I/R-induced injury and during remodeling after myocardial infarction (MI). At baseline, TREK-1 KO mice had similar blood pressure and heart rate as the wild-type (WT) mice. However, the lack of TREK-1 was associated with increased susceptibility to ischemic injury and compromised functional recovery following ex vivo I/R-induced injury. TREK-1 deficiency increased infarct size following permanent coronary artery ligation, resulting in greater systolic dysfunction than the WT counterpart. Electrocardiographic (ECG) analysis revealed QT interval prolongation in TREK-1 KO mice, but normal heart rate (HR). Acutely isolated TREK-1 KO cardiomyocytes exhibited prolonged Ca2+ transient duration associated with action potential duration (APD) prolongation. Our data suggest that TREK-1 has a protective effect against I/R-induced injury and influences the post-MI remodeling processes by regulating membrane potential and maintaining intracellular Ca2+ homeostasis. These data suggest that TREK-1 activation could be an effective strategy to provide cardioprotection against ischemia-induced damage.
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Affiliation(s)
- Samuel Kamatham
- Department of Physiology, University of Tennessee Health Sciences Center, 71 S. Manassas Street, Memphis, TN, 38163, USA
| | - Christopher M Waters
- Department of Physiology, Saha Cardiovascular Research Center, University of Kentucky, Lexington, KY, USA
| | - Andreas Schwingshackl
- Department of Pediatrics, University of California Los Angeles, Los Angeles, CA, USA
| | - Salvatore Mancarella
- Department of Physiology, University of Tennessee Health Sciences Center, 71 S. Manassas Street, Memphis, TN, 38163, USA.
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83
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Jungbauer CG, Maier LS. [Proarrhythmic adverse effects of nonarrhythmic drugs]. Herzschrittmacherther Elektrophysiol 2019; 30:262-267. [PMID: 31444571 DOI: 10.1007/s00399-019-00635-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2019] [Accepted: 07/19/2019] [Indexed: 06/10/2023]
Abstract
Acquired QT prolongation is almost exclusively the result of inhibition of the potassium channel Ikr. Especially hospitalized patients have a high risk to suffer from Torsade de points (TdP). Therefore, any prescription of drugs with the potential for QT prolongation should involve the consideration of the necessity of the agent and interaction with other QT prolonging drugs. The website www.crediblemed.com helps to identify the risk for TdP of each drug. During drug prescription, it is necessary to monitor QTc with regular ECGs; QTc prolongation >500 ms or QTc increase >60 ms should trigger end of drug administration followed by monitoring of the patient according to the individual risk for TdP.
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Affiliation(s)
- C G Jungbauer
- Klinik und Poliklinik für Innere Medizin II, Universitätsklinikum Regensburg, 93053, Regensburg, Deutschland.
| | - L S Maier
- Klinik und Poliklinik für Innere Medizin II, Universitätsklinikum Regensburg, 93053, Regensburg, Deutschland
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84
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Zang K, Zhang Y, Hu J, Wang Y. The Large Conductance Calcium- and Voltage-activated Potassium Channel (BK) and Epilepsy. CNS Neurol Disord Drug Targets 2019; 17:248-254. [PMID: 29623857 DOI: 10.2174/1871527317666180404104055] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Revised: 12/17/2017] [Accepted: 02/26/2018] [Indexed: 11/22/2022]
Abstract
BACKGROUND & OBJECTIVE The large conductance, calcium- and voltage-activated potassium channels (BK) are widely distributed channel proteins which exist in virtually every cell type of mammals and function to influence membrane excitability and Ca2+ signaling. BK channels can be activated by the increase of the intracellular Ca2+ concentration, a consequence of neuronal excitation, and then terminate the action potential with the outward K+ flux. Moreover, after-hyperpolarization induced by BK channels closes Cav channels and thus precludes excessive Ca2+ influx. Considering this negative feedback effect, BK channel seemly acts to decrease membrane excitability in order to prevent hyperexcitation which is a typical characteristic of epilepsy. Therefore, one may reasonably suppose that membrane excitability would increase when the BK channel activity decreases. However, the membrane excitability displays elevation when the function of BK channel is under either upregulated or down-regulated status. Factors altering the activity of BK channels, such as gene mutations, polymorphism, channel openers or blockers that lead to loss- or gain-of-function, have all been linked to epilepsy onset. CONCLUSION The aim of this review is to summarize existing knowledge and recent findings on the molecular properties, signaling complex and channel dysfunction of the BK channels with a particular attention to the possible relevance to the pathophysiology of epilepsy.
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Affiliation(s)
- Kai Zang
- Department of Neurology, Institutes of Brain Science, State Key Laboratory for Medical Neurobiology, Zhongshan Hospital, Fudan University, Shanghai 200032, China
| | - Yuwen Zhang
- Department of Neurology, Institutes of Brain Science, State Key Laboratory for Medical Neurobiology, Zhongshan Hospital, Fudan University, Shanghai 200032, China
| | - Jie Hu
- Department of Neurosurgery, Jingan Hospital, Fudan University, Shanghai, China
| | - Yun Wang
- Department of Neurology, Institutes of Brain Science, State Key Laboratory for Medical Neurobiology, Zhongshan Hospital, Fudan University, Shanghai 200032, China
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85
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Osuma AT, Xu X, Wang Z, Van Camp JA, Freiberg GM. Design and evaluation of pyrazolopyrimidines as KCNQ channel modulators. Bioorg Med Chem Lett 2019; 29:126603. [PMID: 31416667 DOI: 10.1016/j.bmcl.2019.08.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 07/30/2019] [Accepted: 08/04/2019] [Indexed: 10/26/2022]
Abstract
Effective treatments of neuropathic pain have been a focus of many discovery programs. KCNQ (kv7) are voltage gated potassium channel openers that have the potential for the treatment of CNS disorders including neuropathic pain. Clinical studies have suggested agents such as Retigabine to be a modulator of pain-like effects such as hyperalgesia and allodynia. In this paper, we describe the discovery and evaluation of a series of novel pyrazolopyrimidines and their affinity for potassium channels KCNQ2/3. These pyrazolopyrimidines have also shown good efficacy in the capsaicin-induced acute and secondary mechanical allodynia model and excellent pharmacokinetic properties, which may be superior to Retigabine.
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Affiliation(s)
- Augustine T Osuma
- Discovery, AbbVie Inc., North Chicago, IL 60064-6101, United States.
| | - Xiangdong Xu
- Discovery, AbbVie Inc., North Chicago, IL 60064-6101, United States
| | - Zhi Wang
- Discovery, AbbVie Inc., North Chicago, IL 60064-6101, United States
| | | | - Gail M Freiberg
- Discovery, AbbVie Inc., North Chicago, IL 60064-6101, United States
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Murthy A, Workman SW, Jiang M, Hu J, Sifa I, Bernas T, Tang W, Deschenes I, Tseng GN. Dynamic palmitoylation regulates trafficking of K channel interacting protein 2 (KChIP2) across multiple subcellular compartments in cardiac myocytes. J Mol Cell Cardiol 2019; 135:1-9. [PMID: 31362018 DOI: 10.1016/j.yjmcc.2019.07.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 06/26/2019] [Accepted: 07/26/2019] [Indexed: 11/22/2022]
Abstract
BACKGROUND K channel interacting protein 2 (KChIP2), initially cloned as Kv4 channel modulator, is a multi-tasking protein. In addition to modulating several cardiac ion channels at the plasma membrane, it can also modulate microRNA transcription inside nuclei, and interact with presenilins to modulate Ca release through RyR2 in the cytoplasm. However, the mechanism regulating its subcellular distribution is not clear. OBJECTIVE We tested whether palmitoylation drives KChIP2 trafficking and distribution in cells, and whether the distribution pattern of KChIP2 in cardiac myocytes is sensitive to cellular milieu. METHOD We conducted imaging and biochemical experiments on palmitoylatable and unpalmitoylatable KChIP2 variants expressed in COS-7 cells and in cardiomyocytes, and on native KChIP2 in myocytes. RESULTS In COS-7 cells, palmitoylatable KChIP2 clustered to plasma membrane, while unpalmitoylatable KChIP2 exhibited higher cytoplasmic mobility and faster nuclear entry. The same differences in distribution and mobility were observed when these KChIP2 variants were expressed in cardiac myocytes, indicating that the palmitoylation-dependent distribution and trafficking are intrinsic properties of KChIP2. Importantly, acute stress in a rat model of cardiac arrest/resuscitation induced changes in native KChIP2 resembling those of KChIP2 depalmitoylation, promoting KChIP2 nuclear entry. CONCLUSION The palmitoylation status of KChIP2 determines its subcellular distribution in cardiac myocytes. Stress promotes nuclear entry of KChIP2, diverting it from ion channel modulation at the plasma membrane to other functions in the nuclear compartment.
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87
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Abstract
C-type inactivation in potassium channels is a nearly universal regulatory mechanism. A major hypothesis states that C-type inactivation involves ion loss at the selectivity filter as an allosteric response to activation. NMR is used to probe protein conformational changes in response to pH and [K+], demonstrating that H+ and K+ binding are allosterically coupled in KcsA. The lipids are integrated parts of potassium channels in terms of structure, energetics and function.
Inactivation, the slow cessation of transmission after activation, is a general feature of potassium channels. It is essential for their function, and malfunctions in inactivation leads to numerous pathologies. The detailed mechanism for the C-type inactivation, distinct from the N-type inactivation, remains an active area of investigation. Crystallography, computational simulations, and NMR have greatly enriched our understanding of the process. Here we review the major hypotheses regarding C-type inactivation, particularly focusing on the key role played by NMR studies of the prokaryotic potassium channel KcsA, which serves as a good model for voltage gated mammalian channels.
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Affiliation(s)
- Yunyao Xu
- Department of Chemistry, Columbia University, New York, NY 10027, United States
| | - Ann E McDermott
- Department of Chemistry, Columbia University, New York, NY 10027, United States
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88
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Haworth AS, Brackenbury WJ. Emerging roles for multifunctional ion channel auxiliary subunits in cancer. Cell Calcium 2019; 80:125-140. [PMID: 31071485 PMCID: PMC6553682 DOI: 10.1016/j.ceca.2019.04.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 04/16/2019] [Accepted: 04/16/2019] [Indexed: 02/07/2023]
Abstract
Several superfamilies of plasma membrane channels which regulate transmembrane ion flux have also been shown to regulate a multitude of cellular processes, including proliferation and migration. Ion channels are typically multimeric complexes consisting of conducting subunits and auxiliary, non-conducting subunits. Auxiliary subunits modulate the function of conducting subunits and have putative non-conducting roles, further expanding the repertoire of cellular processes governed by ion channel complexes to processes such as transcellular adhesion and gene transcription. Given this expansive influence of ion channels on cellular behaviour it is perhaps no surprise that aberrant ion channel expression is a common occurrence in cancer. This review will focus on the conducting and non-conducting roles of the auxiliary subunits of various Ca2+, K+, Na+ and Cl- channels and the burgeoning evidence linking such auxiliary subunits to cancer. Several subunits are upregulated (e.g. Cavβ, Cavγ) and downregulated (e.g. Kvβ) in cancer, while other subunits have been functionally implicated as oncogenes (e.g. Navβ1, Cavα2δ1) and tumour suppressor genes (e.g. CLCA2, KCNE2, BKγ1) based on in vivo studies. The strengthening link between ion channel auxiliary subunits and cancer has exposed these subunits as potential biomarkers and therapeutic targets. However further mechanistic understanding is required into how these subunits contribute to tumour progression before their therapeutic potential can be fully realised.
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Affiliation(s)
- Alexander S Haworth
- Department of Biology, University of York, Heslington, York, YO10 5DD, UK; York Biomedical Research Institute, University of York, Heslington, York, YO10 5DD, UK
| | - William J Brackenbury
- Department of Biology, University of York, Heslington, York, YO10 5DD, UK; York Biomedical Research Institute, University of York, Heslington, York, YO10 5DD, UK.
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89
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Zhang WH, Liu WZ, He Y, You WJ, Zhang JY, Xu H, Tian XL, Li BM, Mei L, Holmes A, Pan BX. Chronic Stress Causes Projection-Specific Adaptation of Amygdala Neurons via Small-Conductance Calcium-Activated Potassium Channel Downregulation. Biol Psychiatry 2019; 85:812-28. [PMID: 30737013 DOI: 10.1016/j.biopsych.2018.12.010] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 11/17/2018] [Accepted: 12/05/2018] [Indexed: 11/21/2022]
Abstract
BACKGROUND The role of the amygdala in mediating stress coping has been long appreciated. However, basolateral amygdala (BLA) projection neurons (PNs) are organized into discrete output circuits, and it remains unclear whether stress differentially impacts these circuits. METHODS Mice were exposed to acute restraint stress or chronic restraint stress (CRS), and c-fos expression was measured as a proxy for neuronal activation in Retrobead retrogradely labeled dorsomedial prefrontal cortex-targeting PNs (BLA→dmPFC) and non-dmPFC-targeting PNs (BLA↛dmPFC). Next, the effects of CRS on neuronal firing and membrane potassium channel current were examined via ex vivo electrophysiology in these neuronal populations and correlated with anxiety-like behavior, as measured in the elevated plus maze and novel open field tests. Lastly, the ability of virus-mediated overexpression of subtype 2 of small-conductance, calcium-activated potassium (SK2) channel in BLA↛dmPFC PNs to negate the anxiety-related effects of CRS was assessed. RESULTS BLA→dmPFC PNs were transiently activated after CRS, whereas BLA↛dmPFC showed sustained c-fos expression and augmented firing to external input. CRS led to a loss of SK2 channel-mediated currents in BLA↛dmPFC PNs, which correlated with heightened anxiety-like behavior. Virus-mediated maintenance of SK2 channel currents in BLA↛dmPFC PNs prevented CRS-induced anxiety-like behavior. Finally, CRS produced persistent activation of BLA PNs targeting the ventral hippocampus, and virally overexpressing SK2 channels in this projection population were sufficient to prevent CRS-induced anxiety-like behavior. CONCLUSIONS The current data reveal that chronic stress produces projection-specific functional adaptations in BLA PNs. These findings offer new insight into the neural circuits that contribute to stress-induced psychopathology.
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90
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Valdés-Abadía B, Morán-Zendejas R, Rangel-Flores JM, Rodríguez-Menchaca AA. Chloroquine inhibits tumor-related Kv10.1 channel and decreases migration of MDA-MB-231 breast cancer cells in vitro. Eur J Pharmacol 2019; 855:262-6. [PMID: 31082369 DOI: 10.1016/j.ejphar.2019.05.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 04/05/2019] [Accepted: 05/06/2019] [Indexed: 12/25/2022]
Abstract
Chloroquine (CQ) is an old antimalarial drug currently being investigated for its anti-tumor properties. As chloroquine has been shown to inhibits several potassium channels, we decided to study its effect on the tumor-related Kv10.1 channel by using patch-clamp electrophysiology and cell migration assays. We found that chloroquine inhibited Kv10.1 channels transiently expressed in HEK-293 cells in a concentration- and voltage-dependent manner acting from the cytoplasmic side of the plasma membrane. Chloroquine also inhibited the outward potassium currents from MDA-MB-231 cells, which are mainly carried through Kv10.1 channels as was confirmed using astemizole. Additionally, chloroquine decreased MDA-MB-231 cell migration in the in vitro scratch wound healing assay. In conclusion, our data suggest that chloroquine decreases MDA-MB-231 cell migration by inhibiting Kv10.1 channels. The inhibition of Kv10.1 channels could represent another mechanism of the antitumoral action of chloroquine, besides autophagy inhibition and tumor vessel normalization.
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91
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Bashraheel SS, AlQahtani AD, Rashidi FB, Al-Sulaiti H, Domling A, Orie NN, Goda SK. Studies on vascular response to full superantigens and superantigen derived peptides: Possible production of novel superantigen variants with less vasodilation effect for tolerable cancer immunotherapy. Biomed Pharmacother 2019; 115:108905. [PMID: 31060004 DOI: 10.1016/j.biopha.2019.108905] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2019] [Revised: 04/12/2019] [Accepted: 04/22/2019] [Indexed: 12/14/2022] Open
Abstract
Superantigens (SAgs) are a class of antigens that cause non-specific activation of T-cells resulting in polyclonal T cell activation and massive cytokine release and causing symptoms similar to sepsis, e.g. hypotension and subsequent hyporeactivity. We investigated the direct effect of SAgs on vascular tone using two recombinant SAgs, SEA and SPEA. The roles of Nitric Oxide (NO) and potentially hyperpolarization, which is dependent on the K+ channel activation, were also explored. The data show that SEA and SPEA have direct vasodilatory effects that were in part NO-dependent, but completely dependent on activation of K+ channels. Our work also identified the functional regions of one of the superantigens, SPEA, that are involved in causing the vasodilation and possible hypotension. A series of 20 overlapping peptides, spanning the entire sequence of SPEA, were designed and synthesized. The vascular response of each peptide was measured, and the active peptides were identified. Our results implicate the regions, (61-100), (101-140) and (181-220) which cause the vasodilation and possible hypotension effects of SPEA. The data also shows that the peptide 181-220 exert the highest vasodilation effect. This work therefore, demonstrates the direct effect of SAgs on vascular tone and identify the active region causing this vasodilation. We propose that these three peptides could be effective novel antihypertensive drugs. We also overexpressed, in E.coli, four superantigens from codon optimized genes.
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Lancaster E, Burnor E, Zhang J, Lancaster E. ADAM23 is a negative regulator of K v1.1/K v1.4 potassium currents. Neurosci Lett 2019; 704:159-163. [PMID: 30965109 DOI: 10.1016/j.neulet.2019.04.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Revised: 03/12/2019] [Accepted: 04/05/2019] [Indexed: 01/15/2023]
Abstract
Background ADAM22 and ADAM23 are transmembrane proteins that bind the secreted synaptic protein LGI1 and associate with Kv1.1/Kv1.4 potassium channels. However, the roles of these proteins in regulated voltage-gated potassium currents are poorly understood. Methods Cultured cells were transfected to express ADAM22, ADAM23, and Kv1.1/Kv1.4. Voltage-gated potassium currents were measured by whole-cell patch-clamp. Immunostaining Kv1.1 with fluorescent antibodies and fluorescently tagged Kv1.1 subunits was used to measure the effects of ADAM proteins on cell-surface and total expression of Kv1.1 channels. LGI1-conditioned media was added to assess the effect on LGI1 on Kv1.1 currents. Results Cells transfected with Kv1.1/Kv1.4 showed voltage-gated potassium currents (Kv1.1 currents). ADAM23 was a powerful negative regulator of Kv1.1 currents and caused decreased surface expression of Kv1.1 subunits. This decrease in current was not mediated by clathrin-dependent endocytosis. LGI1-conditioned media did not affect the negative regulation of Kv1.1 currents by ADAM23. ADAM22 had no significant effect on Kv1.1 currents by itself, but in the presence of LGI1-conditioned media markedly potentiated Kv1.1 currents without changing channel activation kinetics. Conclusions ADAM22 and ADAM23 have opposite effects on Kv1.1 currents. The relative expression of these proteins, and the availability of LGI1 may shape the expression of Kv1.1 currents in different neuronal membrane domains.
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Affiliation(s)
- Eunjoo Lancaster
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Elisabeth Burnor
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Junxian Zhang
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Eric Lancaster
- Department of Neurology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States.
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Palomo-Ligas L, Gutiérrez-Gutiérrez F, Ochoa-Maganda VY, Cortés-Zárate R, Charles-Niño CL, Castillo-Romero A. Identification of a novel potassium channel (GiK) as a potential drug target in Giardia lamblia: Computational descriptions of binding sites. PeerJ 2019; 7:e6430. [PMID: 30834181 PMCID: PMC6397635 DOI: 10.7717/peerj.6430] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 01/10/2019] [Indexed: 12/12/2022] Open
Abstract
Background The protozoan Giardia lamblia is the causal agent of giardiasis, one of the main diarrheal infections worldwide. Drug resistance to common antigiardial agents and incidence of treatment failures have increased in recent years. Therefore, the search for new molecular targets for drugs against Giardia infection is essential. In protozoa, ionic channels have roles in their life cycle, growth, and stress response. Thus, they are promising targets for drug design. The strategy of ligand-protein docking has demonstrated a great potential in the discovery of new targets and structure-based drug design studies. Methods In this work, we identify and characterize a new potassium channel, GiK, in the genome of Giardia lamblia. Characterization was performed in silico. Because its crystallographic structure remains unresolved, homology modeling was used to construct the three-dimensional model for the pore domain of GiK. The docking virtual screening approach was employed to determine whether GiK is a good target for potassium channel blockers. Results The GiK sequence showed 24–50% identity and 50–90% positivity with 21 different types of potassium channels. The quality assessment and validation parameters indicated the reliability of the modeled structure of GiK. We identified 110 potassium channel blockers exhibiting high affinity toward GiK. A total of 39 of these drugs bind in three specific regions. Discussion The GiK pore signature sequence is related to the small conductance calcium-activated potassium channels (SKCa). The predicted binding of 110 potassium blockers to GiK makes this protein an attractive target for biological testing to evaluate its role in the life cycle of Giardia lamblia and potential candidate for the design of novel antigiardial drugs.
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Affiliation(s)
- Lissethe Palomo-Ligas
- Departamento de Fisiología, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Jalisco, Mexico
| | - Filiberto Gutiérrez-Gutiérrez
- Departamento de Química, Centro Universitario de Ciencias Exactas e Ingenierías, Universidad de Guadalajara, Guadalajara, Jalisco, Mexico
| | - Verónica Yadira Ochoa-Maganda
- Departamento de Fisiología, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Jalisco, Mexico
| | - Rafael Cortés-Zárate
- Departamento de Microbiología y Patología, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Jalisco, Mexico
| | - Claudia Lisette Charles-Niño
- Departamento de Microbiología y Patología, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Jalisco, Mexico
| | - Araceli Castillo-Romero
- Departamento de Microbiología y Patología, Centro Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Jalisco, Mexico
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94
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Zavala WD, Foscolo MR, Kunda PE, Cavicchia JC, Acosta CG. Changes in the expression of the potassium channels TASK1, TASK3 and TRESK in a rat model of oral squamous cell carcinoma and their relation to malignancy. Arch Oral Biol 2019; 100:75-85. [PMID: 30818127 DOI: 10.1016/j.archoralbio.2019.02.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 01/30/2019] [Accepted: 02/15/2019] [Indexed: 12/21/2022]
Abstract
OBJECTIVES Potassium channels have been proposed to promote cancer cell proliferation and metastases. Thus, we investigated the expression pattern of three 2-pore domain potassium channels (K2Ps) TASK1, TASK3 and TRESK in advanced oral squamous cell carcinoma (OSCC), the commonest oral malignancy. DESIGN We used 4-nitroquinoline-1-oxide (4-NQO) to induce high grade OSCC in male adult rats. We then used immunohistochemistry and Western blotting to study the distribution and expression pattern of TASK1, TASK3 and TRESK in normal versus cancerous tissue. We also examined the expression of β-tubulin III (β-tub3), a marker associated with resistance to taxane-based chemotherapy and poor patient prognosis, and its correlation with the K2Ps. Finally, we studied the expression of TASK1, TASK3 and TRESK in human samples of SCC of oral origin. RESULTS We found that TASK3 was significantly up-regulated whereas TASK1 and TRESK were both significantly down-regulated in advanced, poorly differentiated OSCC. Both, rat and human SCC showed a significant increase in the expression of β-tub3. Interestingly, the expression of the latter correlated positively and significantly with TASK3 and TRESK but not TASK1 in rat OSCC. Our initial results showed a similar pattern of up and down regulation and correlation with β-tub3 for these three K2Ps in human SCC. CONCLUSIONS The changes in expression and the co-localization with a marker of resistance to taxanes like β-tub3 turn TASK1, TASK3 and TRESK into potentially new prognostic tools and possibly new therapeutic targets for OSCC.
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Affiliation(s)
- Walther D Zavala
- Facultad de Odontología, Universidad Nacional de Cuyo, Mendoza, Argentina.
| | - Mabel R Foscolo
- Instituto de Histología y Embriología de Mendoza "Dr. M. Burgos" (IHEM-CONICET), Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina.
| | - Patricia E Kunda
- Centro Investigación Medicina Traslacional "Severo Amuchástegui" (CIMETSA), Instituto Universitario Ciencias Biomédicas Córdoba (IUCBC), Córdoba, Argentina.
| | - Juan C Cavicchia
- Instituto de Histología y Embriología de Mendoza "Dr. M. Burgos" (IHEM-CONICET), Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina.
| | - Cristian G Acosta
- Instituto de Histología y Embriología de Mendoza "Dr. M. Burgos" (IHEM-CONICET), Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina
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95
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Dupont C, Denman KS, Hawash AA, Voss AA, Rich MM. Treatment of myotonia congenita with retigabine in mice. Exp Neurol 2019; 315:52-59. [PMID: 30738808 DOI: 10.1016/j.expneurol.2019.02.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 01/10/2019] [Accepted: 02/06/2019] [Indexed: 01/08/2023]
Abstract
Patients with myotonia congenita suffer from muscle stiffness caused by muscle hyperexcitability. Although loss-of-function mutations in the ClC-1 muscle chloride channel have been known for 25 years to cause myotonia congenita, this discovery has led to little progress on development of therapy. Currently, treatment is primarily focused on reducing hyperexcitability by blocking Na+ current. However, other approaches such as increasing K+ currents might also be effective. For example, the K+ channel activator retigabine, which opens KCNQ channels, is effective in treating epilepsy because it causes hyperpolarization of the resting membrane potential in neurons. In this study, we found that retigabine greatly reduced the duration of myotonia in vitro. Detailed study of its mechanism of action revealed that retigabine had no effect on any of the traditional measures of muscle excitability such as resting potential, input resistance or the properties of single action potentials. Instead it appears to shorten myotonia by activating K+ current during trains of action potentials. Retigabine also greatly reduced the severity of myotonia in vivo, which was measured using a muscle force transducer. Despite its efficacy in vivo, retigabine did not improve motor performance of mice with myotonia congenita. There are a number of potential explanations for the lack of motor improvement in vivo including central nervous system side effects. Nonetheless, the striking effectiveness of retigabine on muscle itself suggests that activating potassium currents is an effective method to treat disorders of muscle hyperexcitability.
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Affiliation(s)
- Chris Dupont
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH 45435, United States
| | - Kirsten S Denman
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH 45435, United States
| | - Ahmed A Hawash
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH 45435, United States
| | - Andrew A Voss
- Department of Biological Sciences, Wright State University, Dayton, OH 45435, United States
| | - Mark M Rich
- Department of Neuroscience, Cell Biology and Physiology, Wright State University, Dayton, OH 45435, United States.
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96
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Abstract
Confocal microscopy permits the analysis of the subcellular distribution of proteins. Colocalization between target proteins and specific markers of differential cell compartments provides an efficient approach to studying protein traffic. In this chapter, we describe an automated method to denoise confocal microscopy images and assess the colocalization of their stainings using ImageJ software. As a step further from conventional single colocalization measurements, in the proposed method, we analyze stacks of three different stainings using two-by-two comparisons. To demonstrate the reliability and usefulness of our proposal, the method was used to compare the traffic of the voltage-gated Kv1.3 potassium channel, which is a well-defined plasma membrane protein, in the presence and absence of KCNE4, a regulatory subunit that strongly retains the channel intracellularly.
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97
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Zoukimian C, Meudal H, De Waard S, Ouares KA, Nicolas S, Canepari M, Béroud R, Landon C, De Waard M, Boturyn D. Synthesis by native chemical ligation and characterization of the scorpion toxin AmmTx3. Bioorg Med Chem 2018; 27:247-253. [PMID: 30529150 DOI: 10.1016/j.bmc.2018.12.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 11/28/2018] [Accepted: 12/05/2018] [Indexed: 12/27/2022]
Abstract
The scorpion toxin AmmTx3 is a specific blocker of Kv4 channels. It was shown to have interesting potential for neurological disorders. In this study, we report the first chemical synthesis of AmmTx3 by using the native chemical ligation strategy and validate its biological activity. We determined its 3D structure by nuclear magnetic resonance spectroscopy, and pointed out that AmmTx3 possesses the well-known CSαβ structural motif, which is found in a large number of scorpion toxins. Overall, this study establishes an easy synthetic access to biologically active AmmTx3 toxin.
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Affiliation(s)
- Claude Zoukimian
- Department of Molecular Chemistry, Univ. Grenoble Alpes, CNRS, 570 rue de la chimie, CS 40700, Grenoble 38000, France; Smartox Biotechnology, 6 rue des platanes, Saint Egrève 38120, France
| | - Hervé Meudal
- Center for Molecular Biophysics, CNRS, rue Charles Sadron, CS 80054, Orléans 45071, France
| | - Stephan De Waard
- Institut du Thorax, INSERM, CNRS, Univ. Nantes, 8 quai Moncousu, BP 70721, Nantes 44007, France
| | - Karima Ait Ouares
- Laboratory for Interdisciplinary Physics, Univ. Grenoble Alpes, CNRS, 140 Avenue de la Physique, BP 87, Saint-Martin d'Hères 38402, France
| | - Sébastien Nicolas
- Institut du Thorax, INSERM, CNRS, Univ. Nantes, 8 quai Moncousu, BP 70721, Nantes 44007, France
| | - Marco Canepari
- Laboratory for Interdisciplinary Physics, Univ. Grenoble Alpes, CNRS, 140 Avenue de la Physique, BP 87, Saint-Martin d'Hères 38402, France
| | - Rémy Béroud
- Smartox Biotechnology, 6 rue des platanes, Saint Egrève 38120, France
| | - Céline Landon
- Center for Molecular Biophysics, CNRS, rue Charles Sadron, CS 80054, Orléans 45071, France
| | - Michel De Waard
- Institut du Thorax, INSERM, CNRS, Univ. Nantes, 8 quai Moncousu, BP 70721, Nantes 44007, France
| | - Didier Boturyn
- Department of Molecular Chemistry, Univ. Grenoble Alpes, CNRS, 570 rue de la chimie, CS 40700, Grenoble 38000, France.
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98
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Zhao Y, Chen Z, Cao Z, Li W, Wu Y. Defensins, a novel type of animal toxin-like potassium channel inhibitor. Toxicon 2018; 157:101-105. [PMID: 30472109 DOI: 10.1016/j.toxicon.2018.11.304] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2018] [Revised: 11/03/2018] [Accepted: 11/19/2018] [Indexed: 12/29/2022]
Abstract
The classical potassium channel inhibitors are toxin peptides from venomous animals, and whether there are peptide inhibitors from other species is an open question. Due to both the independent and interdependent relationships between the spear (peptide inhibitors) and the shield (potassium channels), human defensins were first identified by our group as endogenous potassium channel inhibitors. Encouraged by the discovery of human defensins as potassium channel inhibitors, defensins from invertebrates and fungi were successively found by our group to be potassium channel inhibitors. In addition, a plant defensin was reported to be a potassium channel inhibitor. Since defensins are widely produced by vertebrate, invertebrate, plant and fungi species, the recent work established a new research field on defensin-potassium channel interactions. Here, we review the current work on defensins from vertebrate, invertebrate, plant and fungi species as inhibitors of potassium channels and discuss future work in this research field.
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Affiliation(s)
- Yonghui Zhao
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, China
| | - Zongyun Chen
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, China; Department of Biochemistry and Molecular Biology, College of Basic Medicine, Hubei University of Medicine, Hubei, China
| | - Zhijian Cao
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, China; Biodrug Research Center, Wuhan University, Wuhan, 430072, China
| | - Wenxin Li
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, China; Biodrug Research Center, Wuhan University, Wuhan, 430072, China
| | - Yingliang Wu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, 430072, China; Biodrug Research Center, Wuhan University, Wuhan, 430072, China.
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99
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Masuda K, Takanari H, Morishima M, Ma F, Wang Y, Takahashi N, Ono K. Testosterone-mediated upregulation of delayed rectifier potassium channel in cardiomyocytes causes abbreviation of QT intervals in rats. J Physiol Sci 2018; 68:759-767. [PMID: 29332211 PMCID: PMC10717990 DOI: 10.1007/s12576-017-0590-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 12/26/2017] [Indexed: 12/01/2022]
Abstract
Men have shorter rate-corrected QT intervals (QTc) than women, especially at the period of adolescence or later. The aim of this study was to elucidate the long-term effects of testosterone on cardiac excitability parameters including electrocardiogram (ECG) and potassium channel current. Testosterone shortened QT intervals in ECG in castrated male rats, not immediately after, but on day 2 or later. Expression of Kv7.1 (KCNQ1) mRNA was significantly upregulated by testosterone in cardiomyocytes of male and female rats. Short-term application of testosterone was without effect on delayed rectifier potassium channel current (IKs), whereas IKs was significantly increased in cardiomyocytes treated with dihydrotestosterone for 24 h, which was mimicked by isoproterenol (24 h). Gene-selective inhibitors of a transcription factor SP1, mithramycin, abolished the effects of testosterone on Kv7.1. Testosterone increases Kv7.1-IKs possibly through a pathway related to a transcription factor SP1, suggesting a genomic effect of testosterone as an active factor for cardiac excitability.
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Affiliation(s)
- Kimiko Masuda
- Department of Cardiology and Clinical Examination, Oita University School of Medicine, Yufu, Oita, 879-5593, Japan
- Department of Pathophysiology, Oita University School of Medicine, 1-1 Idaigaoka, Hasama, Yufu, Oita, 879-5593, Japan
| | - Hiroki Takanari
- Department of Pathophysiology, Oita University School of Medicine, 1-1 Idaigaoka, Hasama, Yufu, Oita, 879-5593, Japan
| | - Masaki Morishima
- Department of Pathophysiology, Oita University School of Medicine, 1-1 Idaigaoka, Hasama, Yufu, Oita, 879-5593, Japan
| | - FangFang Ma
- Department of Pathophysiology, Oita University School of Medicine, 1-1 Idaigaoka, Hasama, Yufu, Oita, 879-5593, Japan
| | - Yan Wang
- Department of Cardiology and Clinical Examination, Oita University School of Medicine, Yufu, Oita, 879-5593, Japan
- Department of Pathophysiology, Oita University School of Medicine, 1-1 Idaigaoka, Hasama, Yufu, Oita, 879-5593, Japan
| | - Naohiko Takahashi
- Department of Cardiology and Clinical Examination, Oita University School of Medicine, Yufu, Oita, 879-5593, Japan
| | - Katsushige Ono
- Department of Pathophysiology, Oita University School of Medicine, 1-1 Idaigaoka, Hasama, Yufu, Oita, 879-5593, Japan.
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100
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Zhao Y, Xie Z, Feng J, Li W, Cao Z, Wu Y. Pharmacological characterization of human beta-defensins 3 and 4 on potassium channels: Evidence of diversity in beta-defensin-potassium channel interactions. Peptides 2018; 108:14-18. [PMID: 30121363 DOI: 10.1016/j.peptides.2018.08.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Revised: 08/12/2018] [Accepted: 08/13/2018] [Indexed: 12/28/2022]
Abstract
Recent reports have identified defensins as a new type of potassium channel inhibitors; differential binding mechanisms of human β-defensins hBD1 and hBD2 point to complex interactions between human β-defensins and potassium channels. We investigated the inhibitory effects of human defensins hBD3 and hBD4 on potassium channels. The data indicate that hBD3 is a voltage-gated channel subfamily A member 3 (Kv1.3) inhibitor with an IC50 value of 187.6 ± 25.7 nM; 1 μM hBD4 inhibited 34.0 ± 0.2% of Kv1.3 channel currents. Moreover, 1 μM hBD3 inhibited 50.6 ± 3.6% of Kv1.2 channel currents and had smaller effects on Kv1.1, SKCa3, and IKCa channel currents; these effects differed from the Kv1.3 channel-specific inhibitors hBD1 and hBD2. Similar to the pharmacological profiles of hBD1 and hBD2, hBD4 had lower inhibitory effects on Kv1.1, Kv1.2, SKCa3, and IKCa channels. Subsequent mutagenesis and channel activation experiments confirmed that hBD3 binds in a manner similar to that of hBD1, interacting with the outer pore region of the Kv1.3 channel without affecting Kv1.3 channel activation. Thus, the data indicate that the human β-defensin family is a novel group of potassium channel inhibitors with diverse types of human β-defensin-potassium channel interactions.
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Affiliation(s)
- Yonghui Zhao
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Zili Xie
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Jing Feng
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Wenxin Li
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China; Biodrug Research Center, Wuhan University, Wuhan 430072, China
| | - Zhijian Cao
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China; Biodrug Research Center, Wuhan University, Wuhan 430072, China
| | - Yingliang Wu
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China; Biodrug Research Center, Wuhan University, Wuhan 430072, China.
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