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Yakhnitsa V, Thompson J, Ponomareva O, Ji G, Kiritoshi T, Mahimainathan L, Molehin D, Pruitt K, Neugebauer V. Dysfunction of Small-Conductance Ca 2+-Activated Potassium (SK) Channels Drives Amygdala Hyperexcitability and Neuropathic Pain Behaviors: Involvement of Epigenetic Mechanisms. Cells 2024; 13:1055. [PMID: 38920682 PMCID: PMC11201618 DOI: 10.3390/cells13121055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Revised: 06/07/2024] [Accepted: 06/10/2024] [Indexed: 06/27/2024] Open
Abstract
Neuroplasticity in the amygdala and its central nucleus (CeA) is linked to pain modulation and pain behaviors, but cellular mechanisms are not well understood. Here, we addressed the role of small-conductance Ca2+-activated potassium (SK) channels in pain-related amygdala plasticity. The facilitatory effects of the intra-CeA application of an SK channel blocker (apamin) on the pain behaviors of control rats were lost in a neuropathic pain model, whereas an SK channel activator (NS309) inhibited pain behaviors in neuropathic rats but not in sham controls, suggesting the loss of the inhibitory behavioral effects of amygdala SK channels. Brain slice electrophysiology found hyperexcitability of CeA neurons in the neuropathic pain condition due to the loss of SK channel-mediated medium afterhyperpolarization (mAHP), which was accompanied by decreased SK2 channel protein and mRNA expression, consistent with a pretranscriptional mechanisms. The underlying mechanisms involved the epigenetic silencing of the SK2 gene due to the increased DNA methylation of the CpG island of the SK2 promoter region and the change in methylated CpG sites in the CeA in neuropathic pain. This study identified the epigenetic dysregulation of SK channels in the amygdala (CeA) as a novel mechanism of neuropathic pain-related plasticity and behavior that could be targeted to control abnormally enhanced amygdala activity and chronic neuropathic pain.
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Affiliation(s)
- Vadim Yakhnitsa
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Jeremy Thompson
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Olga Ponomareva
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Guangchen Ji
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
- Center of Excellence for Translational Neuroscience and Therapeutics, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Takaki Kiritoshi
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Lenin Mahimainathan
- Department of Pathology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Deborah Molehin
- Department of Immunology and Molecular Microbiology, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
| | - Kevin Pruitt
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Volker Neugebauer
- Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
- Center of Excellence for Translational Neuroscience and Therapeutics, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
- Garrison Institute on Aging, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA
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2
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Orfali R, Alwatban AZ, Orfali RS, Lau L, Chea N, Alotaibi AM, Nam YW, Zhang M. Oxidative stress and ion channels in neurodegenerative diseases. Front Physiol 2024; 15:1320086. [PMID: 38348223 PMCID: PMC10859863 DOI: 10.3389/fphys.2024.1320086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 01/12/2024] [Indexed: 02/15/2024] Open
Abstract
Numerous neurodegenerative diseases result from altered ion channel function and mutations. The intracellular redox status can significantly alter the gating characteristics of ion channels. Abundant neurodegenerative diseases associated with oxidative stress have been documented, including Parkinson's, Alzheimer's, spinocerebellar ataxia, amyotrophic lateral sclerosis, and Huntington's disease. Reactive oxygen and nitrogen species compounds trigger posttranslational alterations that target specific sites within the subunits responsible for channel assembly. These alterations include the adjustment of cysteine residues through redox reactions induced by reactive oxygen species (ROS), nitration, and S-nitrosylation assisted by nitric oxide of tyrosine residues through peroxynitrite. Several ion channels have been directly investigated for their functional responses to oxidizing agents and oxidative stress. This review primarily explores the relationship and potential links between oxidative stress and ion channels in neurodegenerative conditions, such as cerebellar ataxias and Parkinson's disease. The potential correlation between oxidative stress and ion channels could hold promise for developing innovative therapies for common neurodegenerative diseases.
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Affiliation(s)
- Razan Orfali
- Neuroscience Research Department, Research Centre, King Fahad Medical City, Riyadh, Saudi Arabia
| | - Adnan Z. Alwatban
- Neuroscience Research Department, Research Centre, King Fahad Medical City, Riyadh, Saudi Arabia
| | | | - Liz Lau
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, United States
| | - Noble Chea
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, United States
| | - Abdullah M. Alotaibi
- Neuroscience Research Department, Research Centre, King Fahad Medical City, Riyadh, Saudi Arabia
| | - Young-Woo Nam
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, United States
| | - Miao Zhang
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, United States
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3
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Blankenship HE, Carter KA, Cassidy NT, Markiewicz AN, Thellmann MI, Sharpe AL, Freeman WM, Beckstead MJ. VTA dopamine neurons are hyperexcitable in 3xTg-AD mice due to casein kinase 2-dependent SK channel dysfunction. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.16.567486. [PMID: 38014232 PMCID: PMC10680865 DOI: 10.1101/2023.11.16.567486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
Abstract
Alzheimer's disease (AD) patients exhibit neuropsychiatric symptoms that extend beyond classical cognitive deficits, suggesting involvement of subcortical areas. Here, we investigated the role of midbrain dopamine (DA) neurons in AD using the amyloid + tau-driven 3xTg-AD mouse model. We found deficits in reward-based operant learning in AD mice, suggesting possible VTA DA neuron dysregulation. Physiological assessment revealed hyperexcitability and disrupted firing in DA neurons caused by reduced activity of small-conductance calcium-activated potassium (SK) channels. RNA sequencing from contents of single patch-clamped DA neurons (Patch-seq) identified up-regulation of the SK channel modulator casein kinase 2 (CK2). Pharmacological inhibition of CK2 restored SK channel activity and normal firing patterns in 3xTg-AD mice. These findings shed light on a complex interplay between neuropsychiatric symptoms and subcortical circuits in AD, paving the way for novel treatment strategies.
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4
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Orfali R, AlFaiz A, Rahman MA, Lau L, Nam YW, Zhang M. K Ca2 and K Ca3.1 Channels in the Airways: A New Therapeutic Target. Biomedicines 2023; 11:1780. [PMID: 37509419 PMCID: PMC10376499 DOI: 10.3390/biomedicines11071780] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 06/08/2023] [Accepted: 06/13/2023] [Indexed: 07/30/2023] Open
Abstract
K+ channels are involved in many critical functions in lung physiology. Recently, the family of Ca2+-activated K+ channels (KCa) has received more attention, and a massive amount of effort has been devoted to developing selective medications targeting these channels. Within the family of KCa channels, three small-conductance Ca2+-activated K+ (KCa2) channel subtypes, together with the intermediate-conductance KCa3.1 channel, are voltage-independent K+ channels, and they mediate Ca2+-induced membrane hyperpolarization. Many KCa2 channel members are involved in crucial roles in physiological and pathological systems throughout the body. In this article, different subtypes of KCa2 and KCa3.1 channels and their functions in respiratory diseases are discussed. Additionally, the pharmacology of the KCa2 and KCa3.1 channels and the link between these channels and respiratory ciliary regulations will be explained in more detail. In the future, specific modulators for small or intermediate Ca2+-activated K+ channels may offer a unique therapeutic opportunity to treat muco-obstructive lung diseases.
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Affiliation(s)
- Razan Orfali
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA 92618, USA
- Biomedical Research Administration, Research Centre, King Fahad Medical City, Riyadh Second Health Cluster, Riyadh 12231, Saudi Arabia
| | - Ali AlFaiz
- Biomedical Research Administration, Research Centre, King Fahad Medical City, Riyadh Second Health Cluster, Riyadh 12231, Saudi Arabia
| | - Mohammad Asikur Rahman
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA 92618, USA
| | - Liz Lau
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA 92618, USA
| | - Young-Woo Nam
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA 92618, USA
| | - Miao Zhang
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA 92618, USA
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5
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Rosenberg N, Reva M, Binda F, Restivo L, Depierre P, Puyal J, Briquet M, Bernardinelli Y, Rocher AB, Markram H, Chatton JY. Overexpression of UCP4 in astrocytic mitochondria prevents multilevel dysfunctions in a mouse model of Alzheimer's disease. Glia 2023; 71:957-973. [PMID: 36537556 DOI: 10.1002/glia.24317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 10/31/2022] [Accepted: 11/25/2022] [Indexed: 02/16/2023]
Abstract
Alzheimer's disease (AD) is becoming increasingly prevalent worldwide. It represents one of the greatest medical challenges as no pharmacologic treatments are available to prevent disease progression. Astrocytes play crucial functions within neuronal circuits by providing metabolic and functional support, regulating interstitial solute composition, and modulating synaptic transmission. In addition to these physiological functions, growing evidence points to an essential role of astrocytes in neurodegenerative diseases like AD. Early-stage AD is associated with hypometabolism and oxidative stress. Contrary to neurons that are vulnerable to oxidative stress, astrocytes are particularly resistant to mitochondrial dysfunction and are therefore more resilient cells. In our study, we leveraged astrocytic mitochondrial uncoupling and examined neuronal function in the 3xTg AD mouse model. We overexpressed the mitochondrial uncoupling protein 4 (UCP4), which has been shown to improve neuronal survival in vitro. We found that this treatment efficiently prevented alterations of hippocampal metabolite levels observed in AD mice, along with hippocampal atrophy and reduction of basal dendrite arborization of subicular neurons. This approach also averted aberrant neuronal excitability observed in AD subicular neurons and preserved episodic-like memory in AD mice assessed in a spatial recognition task. These findings show that targeting astrocytes and their mitochondria is an effective strategy to prevent the decline of neurons facing AD-related stress at the early stages of the disease.
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Affiliation(s)
- Nadia Rosenberg
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Maria Reva
- Blue Brain Project (BBP), École polytechnique fédérale de Lausanne (EPFL), Geneva, Switzerland
| | - Francesca Binda
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Leonardo Restivo
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Pauline Depierre
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Julien Puyal
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Marc Briquet
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | | | - Anne-Bérengère Rocher
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland
| | - Henry Markram
- Blue Brain Project (BBP), École polytechnique fédérale de Lausanne (EPFL), Geneva, Switzerland
| | - Jean-Yves Chatton
- Department of Fundamental Neurosciences, University of Lausanne, Lausanne, Switzerland.,Cellular Imaging Facility, University of Lausanne, Lausanne, Switzerland
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6
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Halling DB, Philpo AE, Aldrich RW. Calcium dependence of both lobes of calmodulin is involved in binding to a cytoplasmic domain of SK channels. eLife 2022; 11:e81303. [PMID: 36583726 PMCID: PMC9803350 DOI: 10.7554/elife.81303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 12/15/2022] [Indexed: 12/31/2022] Open
Abstract
KCa2.1-3 Ca2+-activated K+-channels (SK) require calmodulin to gate in response to cellular Ca2+. A model for SK gating proposes that the N-terminal domain (N-lobe) of calmodulin is required for activation, but an immobile C-terminal domain (C-lobe) has constitutive, Ca2+-independent binding. Although structures support a domain-driven hypothesis of SK gate activation by calmodulin, only a partial understanding is possible without measuring both channel activity and protein binding. We measured SK2 (KCa2.2) activity using inside-out patch recordings. Currents from calmodulin-disrupted SK2 channels can be restored with exogenously applied calmodulin. We find that SK2 activity only approaches full activation with full-length calmodulin with both an N- and a C-lobe. We measured calmodulin binding to a C-terminal SK peptide (SKp) using both composition-gradient multi-angle light-scattering and tryptophan emission spectra. Isolated lobes bind to SKp with high affinity, but isolated lobes do not rescue SK2 activity. Consistent with earlier models, N-lobe binding to SKp is stronger in Ca2+, and C-lobe-binding affinity is strong independent of Ca2+. However, a native tryptophan in SKp is sensitive to Ca2+ binding to both the N- and C-lobes of calmodulin at Ca2+ concentrations that activate SK2, demonstrating that the C-lobe interaction with SKp changes with Ca2+. Our peptide-binding data and electrophysiology show that SK gating models need deeper scrutiny. We suggest that the Ca2+-dependent associations of both lobes of calmodulin to SKp are crucial events during gating. Additional investigations are necessary to complete a mechanistic gating model consistent with binding, physiology, and structure.
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Affiliation(s)
- David B Halling
- Department of Neuroscience, The University of Texas at AustinAustinUnited States
| | - Ashley E Philpo
- Department of Neuroscience, The University of Texas at AustinAustinUnited States
| | - Richard W Aldrich
- Department of Neuroscience, The University of Texas at AustinAustinUnited States
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7
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Spike Afterhyperpolarizations Govern Persistent Firing Dynamics in Rat Neocortical and Hippocampal Pyramidal Cells. J Neurosci 2022; 42:7690-7706. [PMID: 36414011 PMCID: PMC9581562 DOI: 10.1523/jneurosci.0570-22.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Revised: 08/10/2022] [Accepted: 08/28/2022] [Indexed: 12/14/2022] Open
Abstract
Persistent firing is commonly reported in both cortical and subcortical neurons under a variety of behavioral conditions. Yet the mechanisms responsible for persistent activity are only partially resolved with support for both intrinsic and synaptic circuit-based mechanisms. Little also is known about physiological factors that enable epochs of persistent firing to continue beyond brief pauses and then spontaneously terminate. In the present study, we used intracellular recordings in rat (both sexes) neocortical and hippocampal brain slices to assess the ionic mechanisms underlying persistent firing dynamics. Previously, we showed that blockade of ether-á-go-go-related gene (ERG) potassium channels abolished intrinsic persistent firing in the presence of low concentrations of muscarinic receptor agonists and following optogenetic activation of cholinergic axons. Here we show the slow dynamics of ERG conductance changes allows persistent firing to outlast the triggering stimulus and even to initiate discharges following ∼7 s poststimulus firing pauses. We find that persistent firing dynamics is regulated by the interaction between ERG conductance and spike afterhyperpolarizations (AHPs). Increasing the amplitude of spike AHPs using either SK channel activators or a closed-loop reactive feedback system allows persistent discharges to spontaneously terminate in both neocortical neurons and hippocampal CA1 pyramidal cells. The interplay between ERG and the potassium channels that mediate spike AHPs grades the duration of persistent firing, providing a novel, generalizable mechanism to explain self-terminating persistent firing modes observed behaving animals.SIGNIFICANCE STATEMENT Many classes of neurons generate prolonged spiking responses to transient stimuli. These discharges often outlast the stimulus by seconds to minutes in some in vitro models of persistent firing. While recent work has identified key synaptic and intrinsic components that enable persistent spiking responses, less is known about mechanisms that can terminate and regulate the dynamics of these responses. The present study identified the spike afterhyperpolarizations as a potent mechanism that regulates the duration of persistent firing. We found that amplifying spike afterpotentials converted bistable persistent firing into self-terminating discharges. Varying the spike AHP amplitude grades the duration of persistent discharges, generating in vitro responses that mimic firing modes associated with neurons associated with short-term memory function.
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8
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Metabolic regulation and dysregulation of endothelial small conductance calcium activated potassium channels. Eur J Cell Biol 2022; 101:151208. [DOI: 10.1016/j.ejcb.2022.151208] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 02/06/2022] [Accepted: 02/07/2022] [Indexed: 12/13/2022] Open
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Dwivedi D, Bhalla US. Physiology and Therapeutic Potential of SK, H, and M Medium AfterHyperPolarization Ion Channels. Front Mol Neurosci 2021; 14:658435. [PMID: 34149352 PMCID: PMC8209339 DOI: 10.3389/fnmol.2021.658435] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 04/13/2021] [Indexed: 12/19/2022] Open
Abstract
SK, HCN, and M channels are medium afterhyperpolarization (mAHP)-mediating ion channels. The three channels co-express in various brain regions, and their collective action strongly influences cellular excitability. However, significant diversity exists in the expression of channel isoforms in distinct brain regions and various subcellular compartments, which contributes to an equally diverse set of specific neuronal functions. The current review emphasizes the collective behavior of the three classes of mAHP channels and discusses how these channels function together although they play specialized roles. We discuss the biophysical properties of these channels, signaling pathways that influence the activity of the three mAHP channels, various chemical modulators that alter channel activity and their therapeutic potential in treating various neurological anomalies. Additionally, we discuss the role of mAHP channels in the pathophysiology of various neurological diseases and how their modulation can alleviate some of the symptoms.
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Affiliation(s)
- Deepanjali Dwivedi
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bengaluru, India.,Department of Neurobiology, Harvard Medical School, Boston, MA, United States.,Stanley Center at the Broad, Cambridge, MA, United States
| | - Upinder S Bhalla
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bengaluru, India
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10
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Nam YW, Kong D, Wang D, Orfali R, Sherpa RT, Totonchy J, Nauli SM, Zhang M. Differential modulation of SK channel subtypes by phosphorylation. Cell Calcium 2021; 94:102346. [PMID: 33422768 PMCID: PMC8415101 DOI: 10.1016/j.ceca.2020.102346] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Revised: 12/23/2020] [Accepted: 12/23/2020] [Indexed: 01/01/2023]
Abstract
Small-conductance Ca2+-activated K+ (SK) channels are voltage-independent and are activated by Ca2+ binding to the calmodulin constitutively associated with the channels. Both the pore-forming subunits and the associated calmodulin are subject to phosphorylation. Here, we investigated the modulation of different SK channel subtypes by phosphorylation, using the cultured endothelial cells as a tool. We report that casein kinase 2 (CK2) negatively modulates the apparent Ca2+ sensitivity of SK1 and IK channel subtypes by more than 5-fold, whereas the apparent Ca2+ sensitivity of the SK3 and SK2 subtypes is only reduced by ∼2-fold, when heterologously expressed on the plasma membrane of cultured endothelial cells. The SK2 channel subtype exhibits limited cell surface expression in these cells, partly as a result of the phosphorylation of its C-terminus by cyclic AMP-dependent protein kinase (PKA). SK2 channels expressed on the ER and mitochondria membranes may protect against cell death. This work reveals the subtype-specific modulation of the apparent Ca2+ sensitivity and subcellular localization of SK channels by phosphorylation in cultured endothelial cells.
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Affiliation(s)
- Young-Woo Nam
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, 92618, USA
| | - Dezhi Kong
- Institute of Chinese Integrative Medicine, Hebei Medical University, Shijiazhuang, Hebei, 050017, China
| | - Dong Wang
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, 92618, USA
| | - Razan Orfali
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, 92618, USA
| | - Rinzhin T Sherpa
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, 92618, USA
| | - Jennifer Totonchy
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, 92618, USA
| | - Surya M Nauli
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, 92618, USA
| | - Miao Zhang
- Department of Biomedical and Pharmaceutical Sciences, Chapman University School of Pharmacy, Irvine, CA, 92618, USA.
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11
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Diniz AFA, Ferreira RC, de Souza ILL, da Silva BA. Ionic Channels as Potential Therapeutic Targets for Erectile Dysfunction: A Review. Front Pharmacol 2020; 11:1120. [PMID: 32848741 PMCID: PMC7396897 DOI: 10.3389/fphar.2020.01120] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 07/10/2020] [Indexed: 12/12/2022] Open
Abstract
Erectile dysfunction (ED) is a prevalent condition, especially in men over 40 years old, characterized by the inability to obtain and/or maintain penile erection sufficient for satisfactory sexual intercourse. Several psychological and/or organic factors are involved in the etiopathogenesis of ED. In this context, we gathered evidence of the involvement of Large-conductance, Ca2+-activated K+ channels (BKCa), Small-conductance, Ca2+-activated K+ channels (SKCa), KCNQ-encoded voltage-dependent K+ channels (KV7), Transient Receptor Potential channels (TRP), and Calcium-activated Chloride channels (CaCC) dysfunctions on ED. In addition, the use of modulating agents of these channels are involved in relaxation of the cavernous smooth muscle cell and, consequent penile erection, suggesting that these channels are promising therapeutic targets for the treatment of erectile dysfunction.
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Affiliation(s)
- Anderson Fellyp Avelino Diniz
- Programa de Pós-Graduação em Produtos Naturais e Sintéticos Bioativos, Universidade Federal da Paraíba, João Pessoa, Brazil
| | - Rafael Carlos Ferreira
- Programa de Pós-Graduação em Produtos Naturais e Sintéticos Bioativos, Universidade Federal da Paraíba, João Pessoa, Brazil
| | - Iara Leão Luna de Souza
- Departamento de Ciências Biológicas e da Saúde, Universidade Estadual de Roraima, Boa Vista, Brazil
| | - Bagnólia Araújo da Silva
- Programa de Pós-Graduação em Produtos Naturais e Sintéticos Bioativos, Universidade Federal da Paraíba, João Pessoa, Brazil
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12
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Shrestha A, Sultana R, Adeniyi PA, Lee CC, Ogundele OM. Positive Modulation of SK Channel Impedes Neuron-Specific Cytoskeletal Organization and Maturation. Dev Neurosci 2020; 42:59-71. [PMID: 32580196 PMCID: PMC7486235 DOI: 10.1159/000507989] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 04/15/2020] [Indexed: 01/01/2023] Open
Abstract
N-methyl-D-aspartate receptor (NMDAR) modulates the structural plasticity of dendritic spines by impacting cytoskeletal organization and kinase signaling. In the developing nervous system, activation of NMDAR is pertinent for neuronal migration, neurite differentiation, and cellular organization. Given that small conductance potassium channels (SK2/3) repress NMDAR ionotropic signaling, this study highlights the impact of neonatal SK channel potentiation on adult cortical and hippocampal organization. Neonatal SK channel potentiation was performed by one injection of SK2/3 agonist (CyPPA) into the pallium of mice on postnatal day 2 (P2). When the animals reached adulthood (P55), the hippocampus and cortex were examined to assess neuronal maturation, lamination, and the distribution of synaptic cytoskeletal proteins. Immunodetection of neuronal markers in the brain of P2-treated P55 mice revealed the presence of immature neurons in the upper cortical layers (layers II-IV) and CA1 (hippocampus). Also, layer-dependent cortical-cell density was attenuated due to the ectopic localization of mature (NeuN+) and immature (Doublecortin+ [DCX+]) neurons in cortical layers II-IV. Similarly, the decreased count of NeuN+ neurons in the CA1 is accompanied by an increase in the number of immature DCX+ neurons. Ectopic localization of neurons in the upper cortex and CA1 caused the dramatic expression of neuron-specific cytoskeletal proteins. In line with this, structural deformity of neuronal projections and the loss of postsynaptic densities suggests that postsynaptic integrity is compromised in the SK2/3+ brain. From these results, we deduced that SK channel activity in the developing brain likely impacts neuronal maturation through its effects on cytoskeletal formation.
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Affiliation(s)
- Amita Shrestha
- Department of Comparative Biomedical Sciences, Louisiana State University School of Veterinary Medicine, Baton Rouge, Louisiana, USA
| | - Razia Sultana
- Department of Comparative Biomedical Sciences, Louisiana State University School of Veterinary Medicine, Baton Rouge, Louisiana, USA
| | - Philip A Adeniyi
- Department of Comparative Biomedical Sciences, Louisiana State University School of Veterinary Medicine, Baton Rouge, Louisiana, USA
| | - Charles C Lee
- Department of Comparative Biomedical Sciences, Louisiana State University School of Veterinary Medicine, Baton Rouge, Louisiana, USA
| | - Olalekan M Ogundele
- Department of Comparative Biomedical Sciences, Louisiana State University School of Veterinary Medicine, Baton Rouge, Louisiana, USA,
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13
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Zhou Y, Zhou XE, Gong Y, Zhu Y, Cao X, Brunzelle JS, Xu HE, Zhou M, Melcher K, Zhang F. Structural basis of Fusarium myosin I inhibition by phenamacril. PLoS Pathog 2020; 16:e1008323. [PMID: 32163521 PMCID: PMC7100991 DOI: 10.1371/journal.ppat.1008323] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 03/27/2020] [Accepted: 01/16/2020] [Indexed: 11/26/2022] Open
Abstract
Fusarium is a genus of filamentous fungi that includes species that cause devastating diseases in major staple crops, such as wheat, maize, rice, and barley, resulting in severe yield losses and mycotoxin contamination of infected grains. Phenamacril is a novel fungicide that is considered environmentally benign due to its exceptional specificity; it inhibits the ATPase activity of the sole class I myosin of only a subset of Fusarium species including the major plant pathogens F. graminearum, F. asiaticum and F. fujikuroi. To understand the underlying mechanisms of inhibition, species specificity, and resistance mutations, we have determined the crystal structure of phenamacril-bound F. graminearum myosin I. Phenamacril binds in the actin-binding cleft in a new allosteric pocket that contains the central residue of the regulatory Switch 2 loop and that is collapsed in the structure of a myosin with closed actin-binding cleft, suggesting that pocket occupancy blocks cleft closure. We have further identified a single, transferable phenamacril-binding residue found exclusively in phenamacril-sensitive myosins to confer phenamacril selectivity. Phenamacril is a recently identified myosin I inhibitor that is a potent and highly species-specific and myosin subtype-selective fungicide. We report the high-resolution structure of the phenamacril-bound myosin I motor domain of the major crop pathogen Fusarium graminearum, providing insight into the molecular mechanism of phenamacril action and resistance. These results are of broad significance for understanding the mode of actions of myosin-based fungicides and for designing novel myosin I inhibitors for crop protection and for treatment of human myosin dysfunction diseases.
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Affiliation(s)
- Yuxin Zhou
- Key Laboratory of Pesticide, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- Center of Cancer and Cell Biology, Program for Structural Biology, Van Andel Institute, Grand Rapids, Michigan, United States of America
| | - X. Edward Zhou
- Center of Cancer and Cell Biology, Program for Structural Biology, Van Andel Institute, Grand Rapids, Michigan, United States of America
| | - Yuanping Gong
- Key Laboratory of Pesticide, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Yuanye Zhu
- Key Laboratory of Pesticide, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Xiaoman Cao
- Key Laboratory of Pesticide, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Joseph S. Brunzelle
- Northwestern University Synchrotron Research Center, Life Sciences Collaborative Access Team, Northwestern University, Argonne, Illinois, United States of America
| | - H. Eric Xu
- Center of Cancer and Cell Biology, Program for Structural Biology, Van Andel Institute, Grand Rapids, Michigan, United States of America
- Center for Structure and Function of Drug Targets, The CAS-Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Mingguo Zhou
- Key Laboratory of Pesticide, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- * E-mail: (MZ); (KM); (FZ)
| | - Karsten Melcher
- Center of Cancer and Cell Biology, Program for Structural Biology, Van Andel Institute, Grand Rapids, Michigan, United States of America
- * E-mail: (MZ); (KM); (FZ)
| | - Feng Zhang
- Key Laboratory of Pesticide, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
- * E-mail: (MZ); (KM); (FZ)
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14
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Núñez E, Muguruza-Montero A, Villarroel A. Atomistic Insights of Calmodulin Gating of Complete Ion Channels. Int J Mol Sci 2020; 21:ijms21041285. [PMID: 32075037 PMCID: PMC7072864 DOI: 10.3390/ijms21041285] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 02/07/2020] [Accepted: 02/12/2020] [Indexed: 12/13/2022] Open
Abstract
Intracellular calcium is essential for many physiological processes, from neuronal signaling and exocytosis to muscle contraction and bone formation. Ca2+ signaling from the extracellular medium depends both on membrane potential, especially controlled by ion channels selective to K+, and direct permeation of this cation through specialized channels. Calmodulin (CaM), through direct binding to these proteins, participates in setting the membrane potential and the overall permeability to Ca2+. Over the past years many structures of complete channels in complex with CaM at near atomic resolution have been resolved. In combination with mutagenesis-function, structural information of individual domains and functional studies, different mechanisms employed by CaM to control channel gating are starting to be understood at atomic detail. Here, new insights regarding four types of tetrameric channels with six transmembrane (6TM) architecture, Eag1, SK2/SK4, TRPV5/TRPV6 and KCNQ1–5, and its regulation by CaM are described structurally. Different CaM regions, N-lobe, C-lobe and EF3/EF4-linker play prominent signaling roles in different complexes, emerging the realization of crucial non-canonical interactions between CaM and its target that are only evidenced in the full-channel structure. Different mechanisms to control gating are used, including direct and indirect mechanical actuation over the pore, allosteric control, indirect effect through lipid binding, as well as direct plugging of the pore. Although each CaM lobe engages through apparently similar alpha-helices, they do so using different docking strategies. We discuss how this allows selective action of drugs with great therapeutic potential.
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15
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Villa C, Suphesiz H, Combi R, Akyuz E. Potassium channels in the neuronal homeostasis and neurodegenerative pathways underlying Alzheimer's disease: An update. Mech Ageing Dev 2019; 185:111197. [PMID: 31862274 DOI: 10.1016/j.mad.2019.111197] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 11/27/2019] [Accepted: 12/12/2019] [Indexed: 02/06/2023]
Abstract
With more than 80 subunits, potassium (K+) channels represent a group of ion channels showing high degree of diversity and ubiquity. They play important role in the control of membrane depolarization and cell excitability in several tissues, including the brain. Controlling the intracellular and extracellular K+ flow in cells, they also modulate the hormone and neurotransmitter release, apoptosis and cell proliferation. It is therefore not surprising that an improper functioning of K+ channels in neurons has been associated with pathophysiology of a wide range of neurological disorders, especially Alzheimer's disease (AD). This review aims to give a comprehensive overview of the basic properties and pathophysiological functions of the main classes of K+ channels in the context of disease processes, also discussing the progress, challenges and opportunities to develop drugs targeting these channels as potential pharmacological approach for AD treatment.
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Affiliation(s)
- Chiara Villa
- School of Medicine and Surgery, University of Milano-Bicocca, Italy
| | | | - Romina Combi
- School of Medicine and Surgery, University of Milano-Bicocca, Italy
| | - Enes Akyuz
- Yozgat Bozok University, Medical Faculty, Department of Biophysics, Yozgat, Turkey.
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16
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Shim H, Brown BM, Singh L, Singh V, Fettinger JC, Yarov-Yarovoy V, Wulff H. The Trials and Tribulations of Structure Assisted Design of K Ca Channel Activators. Front Pharmacol 2019; 10:972. [PMID: 31616290 PMCID: PMC6764326 DOI: 10.3389/fphar.2019.00972] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Accepted: 07/29/2019] [Indexed: 11/13/2022] Open
Abstract
Calcium-activated K+ channels constitute attractive targets for the treatment of neurological and cardiovascular diseases. To explain why certain 2-aminobenzothiazole/oxazole-type KCa activators (SKAs) are KCa3.1 selective we previously generated homology models of the C-terminal calmodulin-binding domain (CaM-BD) of KCa3.1 and KCa2.3 in complex with CaM using Rosetta modeling software. We here attempted to employ this atomistic level understanding of KCa activator binding to switch selectivity around and design KCa2.2 selective activators as potential anticonvulsants. In this structure-based drug design approach we used RosettaLigand docking and carefully compared the binding poses of various SKA compounds in the KCa2.2 and KCa3.1 CaM-BD/CaM interface pocket. Based on differences between residues in the KCa2.2 and KCa.3.1 models we virtually designed 168 new SKA compounds. The compounds that were predicted to be both potent and KCa2.2 selective were synthesized, and their activity and selectivity tested by manual or automated electrophysiology. However, we failed to identify any KCa2.2 selective compounds. Based on the full-length KCa3.1 structure it was recently demonstrated that the C-terminal crystal dimer was an artefact and suggested that the "real" binding pocket for the KCa activators is located at the S4-S5 linker. We here confirmed this structural hypothesis through mutagenesis and now offer a new, corrected binding site model for the SKA-type KCa channel activators. SKA-111 (5-methylnaphtho[1,2-d]thiazol-2-amine) is binding in the interface between the CaM N-lobe and the S4-S5 linker where it makes van der Waals contacts with S181 and L185 in the S45A helix of KCa3.1.
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Affiliation(s)
- Heesung Shim
- Department of Pharmacology, School of Medicine, University of California, Davis, Davis, CA, United States.,Department of Chemistry, University of California, Davis, Davis, CA, United States
| | - Brandon M Brown
- Department of Pharmacology, School of Medicine, University of California, Davis, Davis, CA, United States
| | - Latika Singh
- Department of Pharmacology, School of Medicine, University of California, Davis, Davis, CA, United States
| | - Vikrant Singh
- Department of Pharmacology, School of Medicine, University of California, Davis, Davis, CA, United States
| | - James C Fettinger
- Department of Chemistry, University of California, Davis, Davis, CA, United States
| | - Vladimir Yarov-Yarovoy
- Department of Physiology and Membrane Biology, School of Medicine, University of California, Davis, Davis, CA, United States
| | - Heike Wulff
- Department of Pharmacology, School of Medicine, University of California, Davis, Davis, CA, United States
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17
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Kshatri AS, Gonzalez-Hernandez A, Giraldez T. Physiological Roles and Therapeutic Potential of Ca 2+ Activated Potassium Channels in the Nervous System. Front Mol Neurosci 2018; 11:258. [PMID: 30104956 PMCID: PMC6077210 DOI: 10.3389/fnmol.2018.00258] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 07/06/2018] [Indexed: 12/21/2022] Open
Abstract
Within the potassium ion channel family, calcium activated potassium (KCa) channels are unique in their ability to couple intracellular Ca2+ signals to membrane potential variations. KCa channels are diversely distributed throughout the central nervous system and play fundamental roles ranging from regulating neuronal excitability to controlling neurotransmitter release. The physiological versatility of KCa channels is enhanced by alternative splicing and co-assembly with auxiliary subunits, leading to fundamental differences in distribution, subunit composition and pharmacological profiles. Thus, understanding specific KCa channels’ mechanisms in neuronal function is challenging. Based on their single channel conductance, KCa channels are divided into three subtypes: small (SK, 4–14 pS), intermediate (IK, 32–39 pS) and big potassium (BK, 200–300 pS) channels. This review describes the biophysical characteristics of these KCa channels, as well as their physiological roles and pathological implications. In addition, we also discuss the current pharmacological strategies and challenges to target KCa channels for the treatment of various neurological and psychiatric disorders.
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Affiliation(s)
- Aravind S Kshatri
- Department of Basic Medical Sciences, Medical School, Universidad de La Laguna, Tenerife, Spain.,Instituto de Tecnologias Biomedicas, Universidad de La Laguna, Tenerife, Spain
| | - Alberto Gonzalez-Hernandez
- Department of Basic Medical Sciences, Medical School, Universidad de La Laguna, Tenerife, Spain.,Instituto de Tecnologias Biomedicas, Universidad de La Laguna, Tenerife, Spain
| | - Teresa Giraldez
- Department of Basic Medical Sciences, Medical School, Universidad de La Laguna, Tenerife, Spain.,Instituto de Tecnologias Biomedicas, Universidad de La Laguna, Tenerife, Spain
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18
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Lee CH, MacKinnon R. Activation mechanism of a human SK-calmodulin channel complex elucidated by cryo-EM structures. Science 2018; 360:508-513. [PMID: 29724949 DOI: 10.1126/science.aas9466] [Citation(s) in RCA: 123] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 03/16/2018] [Indexed: 12/17/2022]
Abstract
Small-conductance Ca2+-activated K+ (SK) channels mediate neuron excitability and are associated with synaptic transmission and plasticity. They also regulate immune responses and the size of blood cells. Activation of SK channels requires calmodulin (CaM), but how CaM binds and opens SK channels has been unclear. Here we report cryo-electron microscopy (cryo-EM) structures of a human SK4-CaM channel complex in closed and activated states at 3.4- and 3.5-angstrom resolution, respectively. Four CaM molecules bind to one channel tetramer. Each lobe of CaM serves a distinct function: The C-lobe binds to the channel constitutively, whereas the N-lobe interacts with the S4-S5 linker in a Ca2+-dependent manner. The S4-S5 linker, which contains two distinct helices, undergoes conformational changes upon CaM binding to open the channel pore. These structures reveal the gating mechanism of SK channels and provide a basis for understanding SK channel pharmacology.
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Affiliation(s)
- Chia-Hsueh Lee
- Laboratory of Molecular Neurobiology and Biophysics, The Rockefeller University, Howard Hughes Medical Institute, 1230 York Avenue, New York, NY 10065, USA
| | - Roderick MacKinnon
- Laboratory of Molecular Neurobiology and Biophysics, The Rockefeller University, Howard Hughes Medical Institute, 1230 York Avenue, New York, NY 10065, USA.
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19
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A V-to-F substitution in SK2 channels causes Ca 2+ hypersensitivity and improves locomotion in a C. elegans ALS model. Sci Rep 2018; 8:10749. [PMID: 30013223 PMCID: PMC6048120 DOI: 10.1038/s41598-018-28783-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Accepted: 06/29/2018] [Indexed: 11/09/2022] Open
Abstract
Small-conductance Ca2+-activated K+ (SK) channels mediate medium afterhyperpolarization in the neurons and play a key role in the regulation of neuronal excitability. SK channels are potential drug targets for ataxia and Amyotrophic Lateral Sclerosis (ALS). SK channels are activated exclusively by the Ca2+-bound calmodulin. Previously, we identified an intrinsically disordered fragment that is essential for the mechanical coupling between Ca2+/calmodulin binding and channel opening. Here, we report that substitution of a valine to phenylalanine (V407F) in the intrinsically disordered fragment caused a ~6 fold increase in the Ca2+ sensitivity of SK2-a channels. This substitution resulted in a novel interaction between the ectopic phenylalanine and M411, which stabilized PIP2-interacting residue K405, and subsequently enhanced Ca2+ sensitivity. Also, equivalent valine to phenylalanine substitutions in SK1 or SK3 channels conferred Ca2+ hypersensitivity. An equivalent phenylalanine substitution in the Caenorhabditis elegans (C. elegans) SK2 ortholog kcnl-2 partially rescued locomotion defects in an existing C. elegans ALS model, in which human SOD1G85R is expressed at high levels in neurons, confirming that this phenylalanine substitution impacts channel function in vivo. This work for the first time provides a critical reagent for future studies: an SK channel that is hypersensitive to Ca2+ with increased activity in vivo.
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