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Zahra A, Liu R, Han W, Meng H, Wang Q, Wang Y, Campbell SL, Wu J. K Ca-Related Neurological Disorders: Phenotypic Spectrum and Therapeutic Indications. Curr Neuropharmacol 2023; 21:1504-1518. [PMID: 36503451 PMCID: PMC10472807 DOI: 10.2174/1570159x21666221208091805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2022] [Revised: 07/21/2022] [Accepted: 07/23/2022] [Indexed: 12/14/2022] Open
Abstract
Although potassium channelopathies have been linked to a wide range of neurological conditions, the underlying pathogenic mechanism is not always clear, and a systematic summary of clinical manifestation is absent. Several neurological disorders have been associated with alterations of calcium-activated potassium channels (KCa channels), such as loss- or gain-of-function mutations, post-transcriptional modification, etc. Here, we outlined the current understanding of the molecular and cellular properties of three subtypes of KCa channels, including big conductance KCa channels (BK), small conductance KCa channels (SK), and the intermediate conductance KCa channels (IK). Next, we comprehensively reviewed the loss- or gain-of-function mutations of each KCa channel and described the corresponding mutation sites in specific diseases to broaden the phenotypic-genotypic spectrum of KCa-related neurological disorders. Moreover, we reviewed the current pharmaceutical strategies targeting KCa channels in KCa-related neurological disorders to provide new directions for drug discovery in anti-seizure medication.
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Affiliation(s)
- Aqeela Zahra
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, China
- Department of Zoology, University of Sialkot, Sialkot 51310, Pakistan
| | - Ru Liu
- Beijing Tiantan Hospital, Capital Medical University, Beijing 100070, China
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing 100070, China
- National Clinical Research Center for Neurological Diseases, Beijing 100070, China
| | - Wenzhe Han
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, China
| | - Hui Meng
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, China
| | - Qun Wang
- Beijing Tiantan Hospital, Capital Medical University, Beijing 100070, China
- National Clinical Research Center for Neurological Diseases, Beijing 100070, China
| | - YunFu Wang
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, China
| | - Susan L. Campbell
- Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA, United States
| | - Jianping Wu
- School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, China
- Beijing Tiantan Hospital, Capital Medical University, Beijing 100070, China
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, Beijing 100070, China
- National Clinical Research Center for Neurological Diseases, Beijing 100070, China
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2
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Holtzman R, Giulini M, Potestio R. Making sense of complex systems through resolution, relevance, and mapping entropy. Phys Rev E 2022; 106:044101. [PMID: 36397524 DOI: 10.1103/physreve.106.044101] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 08/16/2022] [Indexed: 06/16/2023]
Abstract
Complex systems are characterized by a tight, nontrivial interplay of their constituents, which gives rise to a multiscale spectrum of emergent properties. In this scenario, it is practically and conceptually difficult to identify those degrees of freedom that mostly determine the behavior of the system and separate them from less prominent players. Here, we tackle this problem making use of three measures of statistical information: Resolution, relevance, and mapping entropy. We address the links existing among them, taking the moves from the established relation between resolution and relevance and further developing novel connections between resolution and mapping entropy; by these means we can identify, in a quantitative manner, the number and selection of degrees of freedom of the system that preserve the largest information content about the generative process that underlies an empirical dataset. The method, which is implemented in a freely available software, is fully general, as it is shown through the application to three very diverse systems, namely, a toy model of independent binary spins, a coarse-grained representation of the financial stock market, and a fully atomistic simulation of a protein.
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Affiliation(s)
- Roi Holtzman
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 76100, Israel
| | - Marco Giulini
- Physics Department, University of Trento, via Sommarive, 14 I-38123 Trento, Italy
- INFN-TIFPA, Trento Institute for Fundamental Physics and Applications, I-38123 Trento, Italy
| | - Raffaello Potestio
- Physics Department, University of Trento, via Sommarive, 14 I-38123 Trento, Italy
- INFN-TIFPA, Trento Institute for Fundamental Physics and Applications, I-38123 Trento, Italy
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3
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Kuzmenkov AI, Peigneur S, Nasburg JA, Mineev KS, Nikolaev MV, Pinheiro-Junior EL, Arseniev AS, Wulff H, Tytgat J, Vassilevski AA. Apamin structure and pharmacology revisited. Front Pharmacol 2022; 13:977440. [PMID: 36188602 PMCID: PMC9523135 DOI: 10.3389/fphar.2022.977440] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 08/05/2022] [Indexed: 12/02/2022] Open
Abstract
Apamin is often cited as one of the few substances selectively acting on small-conductance Ca2+-activated potassium channels (KCa2). However, published pharmacological and structural data remain controversial. Here, we investigated the molecular pharmacology of apamin by two-electrode voltage-clamp in Xenopus laevis oocytes and patch-clamp in HEK293, COS7, and CHO cells expressing the studied ion channels, as well as in isolated rat brain neurons. The microtitre broth dilution method was used for antimicrobial activity screening. The spatial structure of apamin in aqueous solution was determined by NMR spectroscopy. We tested apamin against 42 ion channels (KCa, KV, NaV, nAChR, ASIC, and others) and confirmed its unique selectivity to KCa2 channels. No antimicrobial activity was detected for apamin against Gram-positive or Gram-negative bacteria. The NMR solution structure of apamin was deposited in the Protein Data Bank. The results presented here demonstrate that apamin is a selective nanomolar or even subnanomolar-affinity KCa2 inhibitor with no significant effects on other molecular targets. The spatial structure as well as ample functional data provided here support the use of apamin as a KCa2-selective pharmacological tool and as a template for drug design.
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Affiliation(s)
- Alexey I. Kuzmenkov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
| | | | - Joshua A. Nasburg
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Konstantin S. Mineev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
- Moscow Institute of Physics and Technology, Moscow Region, Dolgoprudny, Russia
| | - Maxim V. Nikolaev
- Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, Saint Petersburg, Russia
| | | | - Alexander S. Arseniev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
- Moscow Institute of Physics and Technology, Moscow Region, Dolgoprudny, Russia
| | - Heike Wulff
- Department of Pharmacology, University of California, Davis, Davis, CA, United States
| | - Jan Tytgat
- Toxicology and Pharmacology, KU Leuven, Leuven, Belgium
| | - Alexander A. Vassilevski
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, Russia
- Moscow Institute of Physics and Technology, Moscow Region, Dolgoprudny, Russia
- *Correspondence: Alexander A. Vassilevski,
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4
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Das B, Saviola AJ, Mukherjee AK. Biochemical and Proteomic Characterization, and Pharmacological Insights of Indian Red Scorpion Venom Toxins. Front Pharmacol 2021; 12:710680. [PMID: 34650430 PMCID: PMC8505525 DOI: 10.3389/fphar.2021.710680] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2021] [Accepted: 08/16/2021] [Indexed: 12/16/2022] Open
Abstract
The Indian red scorpion (Mesobuthus tamulus) is one of the world's deadliest scorpions, with stings representing a life-threatening medical emergency. This species is distributed throughout the Indian sub-continent, including eastern Pakistan, eastern Nepal, and Sri Lanka. In India, Indian red scorpions are broadly distributed in western Maharashtra, Saurashtra, Kerala, Andhra Pradesh, Tamil Nadu, and Karnataka; however, fatal envenomations have been recorded primarily in the Konkan region of Maharashtra. The Indian red scorpion venom proteome comprises 110 proteins belonging to 13 venom protein families. The significant pharmacological activity is predominantly caused by the low molecular mass non-enzymatic Na+ and K+ ion channel toxins. Other minor toxins comprise 15.6% of the total venom proteome. Indian red scorpion stings induce the release of catecholamine, which leads to pathophysiological abnormalities in the victim. A strong correlation has been observed between venom proteome composition and local (swelling, redness, heat, and regional lymph node involvement) and systemic (tachycardia, mydriasis, hyperglycemia, hypertension, toxic myocarditis, cardiac failure, and pulmonary edema) manifestations. Immediate administration of antivenom is the preferred treatment for Indian red scorpion stings. However, scorpion-specific antivenoms have exhibited poor immunorecognition and neutralization of the low molecular mass toxins. The proteomic analysis also suggests that Indian red scorpion venom is a rich source of pharmacologically active molecules that may be envisaged as drug prototypes. The following review summarizes the progress made towards understanding the venom proteome of the Indian red scorpion and addresses the current understanding of the pathophysiology associated with its sting.
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Affiliation(s)
- Bhabana Das
- Department of Molecular Biology and Biotechnology, School of Sciences, Tezpur University, Tezpur, India
| | - Anthony J. Saviola
- Department of Biochemistry and Molecular Genetics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Ashis K. Mukherjee
- Department of Molecular Biology and Biotechnology, School of Sciences, Tezpur University, Tezpur, India
- Institute of Advanced Study in Science and Technology, Guwahati, India
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5
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Abstract
K+ channels enable potassium to flow across the membrane with great selectivity. There are four K+ channel families: voltage-gated K (Kv), calcium-activated (KCa), inwardly rectifying K (Kir), and two-pore domain potassium (K2P) channels. All four K+ channels are formed by subunits assembling into a classic tetrameric (4x1P = 4P for the Kv, KCa, and Kir channels) or tetramer-like (2x2P = 4P for the K2P channels) architecture. These subunits can either be the same (homomers) or different (heteromers), conferring great diversity to these channels. They share a highly conserved selectivity filter within the pore but show different gating mechanisms adapted for their function. K+ channels play essential roles in controlling neuronal excitability by shaping action potentials, influencing the resting membrane potential, and responding to diverse physicochemical stimuli, such as a voltage change (Kv), intracellular calcium oscillations (KCa), cellular mediators (Kir), or temperature (K2P).
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6
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Errica F, Giulini M, Bacciu D, Menichetti R, Micheli A, Potestio R. A Deep Graph Network-Enhanced Sampling Approach to Efficiently Explore the Space of Reduced Representations of Proteins. Front Mol Biosci 2021; 8:637396. [PMID: 33996896 PMCID: PMC8116519 DOI: 10.3389/fmolb.2021.637396] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 02/17/2021] [Indexed: 12/12/2022] Open
Abstract
The limits of molecular dynamics (MD) simulations of macromolecules are steadily pushed forward by the relentless development of computer architectures and algorithms. The consequent explosion in the number and extent of MD trajectories induces the need for automated methods to rationalize the raw data and make quantitative sense of them. Recently, an algorithmic approach was introduced by some of us to identify the subset of a protein's atoms, or mapping, that enables the most informative description of the system. This method relies on the computation, for a given reduced representation, of the associated mapping entropy, that is, a measure of the information loss due to such simplification; albeit relatively straightforward, this calculation can be time-consuming. Here, we describe the implementation of a deep learning approach aimed at accelerating the calculation of the mapping entropy. We rely on Deep Graph Networks, which provide extreme flexibility in handling structured input data and whose predictions prove to be accurate and-remarkably efficient. The trained network produces a speedup factor as large as 105 with respect to the algorithmic computation of the mapping entropy, enabling the reconstruction of its landscape by means of the Wang-Landau sampling scheme. Applications of this method reach much further than this, as the proposed pipeline is easily transferable to the computation of arbitrary properties of a molecular structure.
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Affiliation(s)
- Federico Errica
- Department of Computer Science, University of Pisa, Pisa, Italy
| | - Marco Giulini
- Physics Department, University of Trento, Trento, Italy
- INFN-TIFPA, Trento Institute for Fundamental Physics and Applications, Trento, Italy
| | - Davide Bacciu
- Department of Computer Science, University of Pisa, Pisa, Italy
| | - Roberto Menichetti
- Physics Department, University of Trento, Trento, Italy
- INFN-TIFPA, Trento Institute for Fundamental Physics and Applications, Trento, Italy
| | - Alessio Micheli
- Department of Computer Science, University of Pisa, Pisa, Italy
| | - Raffaello Potestio
- Physics Department, University of Trento, Trento, Italy
- INFN-TIFPA, Trento Institute for Fundamental Physics and Applications, Trento, Italy
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7
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Setayesh-Mehr Z, Poorsargol M. Toxic proteins application in cancer therapy. Mol Biol Rep 2021; 48:3827-3840. [PMID: 33895972 DOI: 10.1007/s11033-021-06363-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Accepted: 04/16/2021] [Indexed: 12/19/2022]
Abstract
Ribosome inactivating proteins (RIPs) as family of anti-cancer drugs recently received much attention due to their interesting anti-cancer mechanism. In spite of small drugs, RIPs use the large-size effect (LSE) to prevent the efflux process governed by drug resistance transporters (DRTs) which prevents inside of the cells against drug transfection. There are many clinical translation obstacles that severely restrict their applications especially their delivery approach to the tumor cells. As the main goal of this review, we will focus on trichosanthin (TCS) and gelonin (Gel) and other types, especially scorpion venom-derived RIPs to clarify that they are struggling with what types of bio-barriers and these challenges could be solved in cancer therapy science. Then, we will try to highlight recent state-of-the-arts in delivery of RIPs for cancer therapy.
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Affiliation(s)
- Zahra Setayesh-Mehr
- Department of Biology, Faculty of Sciences, University of Zabol, Zabol, Iran.
| | - Mahdiye Poorsargol
- Department of Chemistry, Faculty of Sciences, University of Zabol, Zabol, Iran
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8
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Choromańska A, Chwiłkowska A, Kulbacka J, Baczyńska D, Rembiałkowska N, Szewczyk A, Michel O, Gajewska-Naryniecka A, Przystupski D, Saczko J. Modifications of Plasma Membrane Organization in Cancer Cells for Targeted Therapy. Molecules 2021; 26:1850. [PMID: 33806009 PMCID: PMC8037978 DOI: 10.3390/molecules26071850] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 03/18/2021] [Accepted: 03/23/2021] [Indexed: 12/11/2022] Open
Abstract
Modifications of the composition or organization of the cancer cell membrane seem to be a promising targeted therapy. This approach can significantly enhance drug uptake or intensify the response of cancer cells to chemotherapeutics. There are several methods enabling lipid bilayer modifications, e.g., pharmacological, physical, and mechanical. It is crucial to keep in mind the significance of drug resistance phenomenon, ion channel and specific receptor impact, and lipid bilayer organization in planning the cell membrane-targeted treatment. In this review, strategies based on cell membrane modulation or reorganization are presented as an alternative tool for future therapeutic protocols.
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Affiliation(s)
- Anna Choromańska
- Department of Molecular and Cellular Biology, Wroclaw Medical University, Borowska 211A, 50-556 Wroclaw, Poland; (J.K.); (D.B.); (N.R.); (A.S.); (O.M.); (A.G.-N.); (J.S.)
| | - Agnieszka Chwiłkowska
- Department of Molecular and Cellular Biology, Wroclaw Medical University, Borowska 211A, 50-556 Wroclaw, Poland; (J.K.); (D.B.); (N.R.); (A.S.); (O.M.); (A.G.-N.); (J.S.)
| | - Julita Kulbacka
- Department of Molecular and Cellular Biology, Wroclaw Medical University, Borowska 211A, 50-556 Wroclaw, Poland; (J.K.); (D.B.); (N.R.); (A.S.); (O.M.); (A.G.-N.); (J.S.)
| | - Dagmara Baczyńska
- Department of Molecular and Cellular Biology, Wroclaw Medical University, Borowska 211A, 50-556 Wroclaw, Poland; (J.K.); (D.B.); (N.R.); (A.S.); (O.M.); (A.G.-N.); (J.S.)
| | - Nina Rembiałkowska
- Department of Molecular and Cellular Biology, Wroclaw Medical University, Borowska 211A, 50-556 Wroclaw, Poland; (J.K.); (D.B.); (N.R.); (A.S.); (O.M.); (A.G.-N.); (J.S.)
| | - Anna Szewczyk
- Department of Molecular and Cellular Biology, Wroclaw Medical University, Borowska 211A, 50-556 Wroclaw, Poland; (J.K.); (D.B.); (N.R.); (A.S.); (O.M.); (A.G.-N.); (J.S.)
| | - Olga Michel
- Department of Molecular and Cellular Biology, Wroclaw Medical University, Borowska 211A, 50-556 Wroclaw, Poland; (J.K.); (D.B.); (N.R.); (A.S.); (O.M.); (A.G.-N.); (J.S.)
| | - Agnieszka Gajewska-Naryniecka
- Department of Molecular and Cellular Biology, Wroclaw Medical University, Borowska 211A, 50-556 Wroclaw, Poland; (J.K.); (D.B.); (N.R.); (A.S.); (O.M.); (A.G.-N.); (J.S.)
| | - Dawid Przystupski
- Department of Paediatric Bone Marrow Transplantation, Oncology and Haematology, Wroclaw Medical University, Borowska 213, 50-556 Wroclaw, Poland;
| | - Jolanta Saczko
- Department of Molecular and Cellular Biology, Wroclaw Medical University, Borowska 211A, 50-556 Wroclaw, Poland; (J.K.); (D.B.); (N.R.); (A.S.); (O.M.); (A.G.-N.); (J.S.)
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9
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Singh SK, Mandal MB, Ravindran R. Instillation of bradykinin into femoral artery elicits cardiorespiratory reflexes involving perivascular afferents in anesthetized rats. Physiol Int 2021; 107:40-54. [PMID: 32491287 DOI: 10.1556/2060.2020.00009] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2019] [Accepted: 01/07/2020] [Indexed: 11/19/2022]
Abstract
The physiology of baroreceptors and chemoreceptors present in large blood vessels of the heart is well known in the regulation of cardiorespiratory functions. Since large blood vessels and peripheral blood vessels are of the same mesodermal origin, therefore, involvement of the latter in the regulation of cardiorespiratory system is expected. The role of perivascular nerves in mediating cardiorespiratory alterations produced after intra-arterial injection of a nociceptive agent (bradykinin) was examined in urethane-anesthetized male rats. Respiratory frequency, blood pressure, and heart rate were recorded for 30 min after the retrograde injection of bradykinin/saline into the femoral artery. In addition, paw edema was determined and water content was expressed as percentage of wet weight. Injection of bradykinin produced immediate tachypneic, hypotensive and bradycardiac responses of shorter latency (5-8 s) favoring the neural mechanisms involved in it. Injection of equi-volume of saline did not produce any responses and served as time-matched control. Paw edema was observed in the ipsilateral hind limb. Pretreatment with diclofenac sodium significantly attenuated the bradykinin-induced responses and also blocked the paw edema. Ipsilateral femoral and sciatic nerve sectioning attenuated bradykinin-induced responses significantly, indicating the origin of responses from the local vascular bed. Administration of bradykinin in the segment of an artery produced reflex cardiorespiratory changes by stimulating the perivascular nociceptors involving prostaglandins. This is a novel study exhibiting the role of peripheral blood vessels in the regulation of the cardiorespiratory system.
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Affiliation(s)
| | - M B Mandal
- Department of Physiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, UP, India
| | - R Ravindran
- Department of Physiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, UP, India
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10
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Abstract
Potassium channels are the most diverse and ubiquitous family of ion channels found in cells. The Ca2+ and voltage gated members form a subfamily that play a variety of roles in both excitable and non-excitable cells and are further classified on the basis of their single channel conductance to form the small conductance (SK), intermediate conductance (IK) and big conductance (BK) K+ channels.In this chapter, we will focus on the mechanisms underlying the gating of BK channels, whose function is modified in different tissues by different splice variants as well as the expanding array of regulatory accessory subunits including β, γ and LINGO subunits. We will examine how BK channels are modified by these regulatory subunits and describe how the channel gating is altered by voltage and Ca2+ whilst setting this in context with the recently published structures of the BK channel. Finally, we will discuss how BK and other calcium-activated channels are modulated by novel ion channel modulators and describe some of the challenges associated with trying to develop compounds with sufficient efficacy, potency and selectivity to be of therapeutic benefit.
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11
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Arsenault D, Tremblay C, Emond V, Calon F. Sex-dependent alterations in the physiology of entorhinal cortex neurons in old heterozygous 3xTg-AD mice. Biol Sex Differ 2020; 11:63. [PMID: 33198813 PMCID: PMC7667843 DOI: 10.1186/s13293-020-00337-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2020] [Accepted: 10/15/2020] [Indexed: 01/29/2023] Open
Abstract
While the higher prevalence of Alzheimer’s disease (AD) in women is clear, studies suggest that biological sex may also influence AD pathogenesis. However, mechanisms behind these differences are not clear. To investigate physiological differences between sexes at the cellular level in the brain, we investigated the intrinsic and synaptic properties of entorhinal cortex neurons in heterozygous 3xTg-AD mice of both sexes at the age of 20 months. This brain region was selected because of its early association with AD symptoms. First, we found physiological differences between male and female non-transgenic mice, providing indirect evidence of axonal alterations in old females. Second, we observed a transgene-dependent elevation of the firing activity, post-burst afterhyperpolarization (AHP), and spontaneous excitatory postsynaptic current (EPSC) activity, without any effect of sex. Third, the passive properties and the hyperpolarization-activated current (Ih) were altered by transgene expression only in female mice, whereas the paired-pulse ratio (PPR) of evoked EPSC was changed only in males. Fourth, both sex and transgene expression were associated with changes in action potential properties. Consistent with previous work, higher levels of Aβ neuropathology were detected in 3xTg-AD females, whereas tau deposition was similar. In summary, our results support the idea that aging and AD neuropathology differentially alter the physiology of entorhinal cortex neurons in males and females.
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Affiliation(s)
- Dany Arsenault
- Faculty of Pharmacy, Université Laval, Quebec City, QC, Canada.,Neuroscience, Centre de Recherche du CHU de Québec (CHUQ), Quebec City, QC, Canada.,Physiotek, Quebec City, QC, Canada
| | - Cyntia Tremblay
- Neuroscience, Centre de Recherche du CHU de Québec (CHUQ), Quebec City, QC, Canada
| | - Vincent Emond
- Neuroscience, Centre de Recherche du CHU de Québec (CHUQ), Quebec City, QC, Canada
| | - Frédéric Calon
- Faculty of Pharmacy, Université Laval, Quebec City, QC, Canada. .,Neuroscience, Centre de Recherche du CHU de Québec (CHUQ), Quebec City, QC, Canada.
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12
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Giulini M, Menichetti R, Shell MS, Potestio R. An Information-Theory-Based Approach for Optimal Model Reduction of Biomolecules. J Chem Theory Comput 2020; 16:6795-6813. [PMID: 33108737 PMCID: PMC7659038 DOI: 10.1021/acs.jctc.0c00676] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Indexed: 02/06/2023]
Abstract
In theoretical modeling of a physical system, a crucial step consists of the identification of those degrees of freedom that enable a synthetic yet informative representation of it. While in some cases this selection can be carried out on the basis of intuition and experience, straightforward discrimination of the important features from the negligible ones is difficult for many complex systems, most notably heteropolymers and large biomolecules. We here present a thermodynamics-based theoretical framework to gauge the effectiveness of a given simplified representation by measuring its information content. We employ this method to identify those reduced descriptions of proteins, in terms of a subset of their atoms, that retain the largest amount of information from the original model; we show that these highly informative representations share common features that are intrinsically related to the biological properties of the proteins under examination, thereby establishing a bridge between protein structure, energetics, and function.
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Affiliation(s)
- Marco Giulini
- Physics
Department, University of Trento, via Sommarive 14, I-38123 Trento, Italy
- INFN-TIFPA, Trento
Institute for Fundamental Physics and Applications, I-38123 Trento, Italy
| | - Roberto Menichetti
- Physics
Department, University of Trento, via Sommarive 14, I-38123 Trento, Italy
- INFN-TIFPA, Trento
Institute for Fundamental Physics and Applications, I-38123 Trento, Italy
| | - M. Scott Shell
- Department
of Chemical Engineering, University of California
Santa Barbara, Santa
Barbara, California 93106, United States
| | - Raffaello Potestio
- Physics
Department, University of Trento, via Sommarive 14, I-38123 Trento, Italy
- INFN-TIFPA, Trento
Institute for Fundamental Physics and Applications, I-38123 Trento, Italy
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13
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Mayorga-Flores M, Chantôme A, Melchor-Meneses CM, Domingo I, Titaux-Delgado GA, Galindo-Murillo R, Vandier C, del Río-Portilla F. Novel Blocker of Onco SK3 Channels Derived from Scorpion Toxin Tamapin and Active against Migration of Cancer Cells. ACS Med Chem Lett 2020; 11:1627-1633. [PMID: 32832033 DOI: 10.1021/acsmedchemlett.0c00300] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 07/10/2020] [Indexed: 11/28/2022] Open
Abstract
Peptide-based therapy against cancer is a field of great interest for biomedical developments. Since it was shown that SK3 channels promote cancer cell migration and metastatic development, we started using these channels as targets for the development of antimetastatic drugs. Particularly, tamapin (a peptide found in the venom of the scorpion Mesobuthus tamulus) is the most specific toxin against the SK2 channel currently known. Considering this fact, we designed diverse tamapin mutants based on three different hypotheses to discover a new potent molecule to block SK3 channels. We performed in vitro studies to evaluate this new toxin derivative inhibitor of cancer cell migration. Our results can be used to generate a new tamapin-based therapy against cancer cells that express SK3 channels.
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Affiliation(s)
- Marlen Mayorga-Flores
- Departamento de Química de Biomacromoléculas, Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior s/n, Ciudad Universitaria, 04510 Ciudad de México, Mexico
| | - Aurélie Chantôme
- N2C UMR 1069, University of Tours, INSERM, Faculté de Pharmacie, Calciscreen Platform, 37032 Tours, France
| | - Carolina Monserrath Melchor-Meneses
- Departamento de Química de Biomacromoléculas, Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior s/n, Ciudad Universitaria, 04510 Ciudad de México, Mexico
| | - Isabelle Domingo
- N2C UMR 1069, University of Tours, INSERM, Calciscreen Platform, 37032 Tours, France
| | - Gustavo Alfredo Titaux-Delgado
- Departamento de Química de Biomacromoléculas, Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior s/n, Ciudad Universitaria, 04510 Ciudad de México, Mexico
| | - Rodrigo Galindo-Murillo
- Department of Medicinal Chemistry, L. S. Skaggs Pharmacy Institute, University of Utah, Salt Lake City, Utah 84112, United States
| | - Christophe Vandier
- N2C UMR 1069, University of Tours, INSERM, Calciscreen Platform, 37032 Tours, France
| | - Federico del Río-Portilla
- Departamento de Química de Biomacromoléculas, Instituto de Química, Universidad Nacional Autónoma de México, Circuito Exterior s/n, Ciudad Universitaria, 04510 Ciudad de México, Mexico
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14
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Díaz-García A, Varela D. Voltage-Gated K +/Na + Channels and Scorpion Venom Toxins in Cancer. Front Pharmacol 2020; 11:913. [PMID: 32655396 PMCID: PMC7325878 DOI: 10.3389/fphar.2020.00913] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Accepted: 06/04/2020] [Indexed: 12/25/2022] Open
Abstract
Ion channels have recently been recognized as novel therapeutic targets in cancer research since they are overexpressed in different histological tissues, and their activity is linked to proliferation, tumor progression, angiogenesis, metastasis, and apoptosis. Voltage gated-potassium channels (VGKC) are involved in cell proliferation, cancer progression, cell cycle transition, and apoptosis. Moreover, voltage-dependent sodium channels (VGSC) contribute to decreases in extracellular pH, which, in turn, promotes cancer cell migration and invasion. Furthermore, VGSC and VGKC modulate voltage-sensitive Ca2+ channel activity by controlling the membrane potential and regulating Ca2+ influx, which functions as a second messenger in processes related to proliferation, invasion, migration, and metastasis. The subgroup of these types of channels that have shown a high oncogenic potential have become known as "oncochannels", and the evidence has highlighted them as key potential therapeutic targets. Scorpion venoms contain a high proportion of peptide toxins that act by modulating voltage-gated Na+/K+ channel activity. Increasing scientific data have pointed out that scorpion venoms and their toxins can affect the activity of oncochannels, thus showing their potential for anticancer therapy. In this review, we provide an update of the most relevant voltage-gated Na+\K+ ion channels as cellular targets and discuss the possibility of using scorpion venom and toxins for anticancer therapy.
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Affiliation(s)
- Alexis Díaz-García
- LifEscozul Chile SpA, Santiago, Chile
- Millennium Nucleus of Ion Channel-Associated Diseases (MiNICAD), Universidad de Chile, Santiago, Chile
| | - Diego Varela
- Millennium Nucleus of Ion Channel-Associated Diseases (MiNICAD), Universidad de Chile, Santiago, Chile
- Program of Physiology and Biophysics, Faculty of Medicine, Institute of Biomedical Sciences (ICBM), Universidad de Chile, Santiago, Chile
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15
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Scorpion Toxins and Ion Channels: Potential Applications in Cancer Therapy. Toxins (Basel) 2020; 12:toxins12050326. [PMID: 32429050 PMCID: PMC7290751 DOI: 10.3390/toxins12050326] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 04/14/2020] [Accepted: 04/15/2020] [Indexed: 12/24/2022] Open
Abstract
Apoptosis, a genetically directed process of cell death, has been studied for many years, and the biochemical mechanisms that surround it are well known and described. There are at least three pathways by which apoptosis occurs, and each pathway depends on extra or intracellular processes for activation. Apoptosis is a vital process, but disturbances in proliferation and cell death rates can lead to the development of diseases like cancer. Several compounds, isolated from scorpion venoms, exhibit inhibitory effects on different cancer cells. Indeed, some of these compounds can differentiate between healthy and cancer cells within the same tissue. During the carcinogenic process, morphological, biochemical, and biological changes occur that enable these compounds to modulate cancer but not healthy cells. This review highlights cancer cell features that enable modulation by scorpion neurotoxins. The properties of the isolated scorpion neurotoxins in cancer cells and the potential uses of these compounds as alternative treatments for cancer are discussed.
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16
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Mohammad S, Page SJ, Wang L, Ishii S, Li P, Sasaki T, Basha A, Salzberg A, Quezado Z, Imamura F, Nishi H, Isaka K, Corbin JG, Liu JS, Kawasawa YI, Torii M, Hashimoto-Torii K. Kcnn2 blockade reverses learning deficits in a mouse model of fetal alcohol spectrum disorders. Nat Neurosci 2020; 23:533-543. [PMID: 32203497 PMCID: PMC7131887 DOI: 10.1038/s41593-020-0592-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 01/16/2020] [Indexed: 12/19/2022]
Abstract
Learning disabilities are hallmarks of congenital conditions caused by prenatal exposure to harmful agents. Those include Fetal Alcohol Spectrum Disorders (FASD) with a wide range of cognitive deficiencies including impaired motor skill development. While these effects have been well characterized, the molecular effects that bring about these behavioral consequences remain to be determined. We have previously found that the acute molecular responses to alcohol in the embryonic brain are stochastic, varying among neural progenitor cells. However, the pathophysiological consequences stemming from these heterogeneous responses remain unknown. Here we show that acute responses to alcohol in progenitor cells alter gene expression in their descendant neurons. Among the altered genes, an increase of the calcium-activated potassium channel Kcnn2 in the motor cortex correlates with motor learning deficits in the mouse model of FASD. Pharmacologic blockade of Kcnn2 improves these learning deficits, suggesting Kcnn2 blockers as a novel intervention for learning disabilities in FASD.
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Affiliation(s)
- Shahid Mohammad
- Center for Neuroscience Research, Children's Research Institute, Children's National Hospital, Washington, DC, USA
| | - Stephen J Page
- Center for Neuroscience Research, Children's Research Institute, Children's National Hospital, Washington, DC, USA
| | - Li Wang
- Center for Neuroscience Research, Children's Research Institute, Children's National Hospital, Washington, DC, USA
| | - Seiji Ishii
- Center for Neuroscience Research, Children's Research Institute, Children's National Hospital, Washington, DC, USA
| | - Peijun Li
- Center for Neuroscience Research, Children's Research Institute, Children's National Hospital, Washington, DC, USA.,Wenzhou Medical University, Ouhai, Wenzhou, China
| | - Toru Sasaki
- Center for Neuroscience Research, Children's Research Institute, Children's National Hospital, Washington, DC, USA.,Department of Obstetrics and Gynecology, Tokyo Medical University, Tokyo, Japan
| | - Aiesha Basha
- Center for Neuroscience Research, Children's Research Institute, Children's National Hospital, Washington, DC, USA
| | - Anna Salzberg
- Department of Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Zenaide Quezado
- The Sheikh Zayed Institute for Pediatric Surgical Innovation, Division of Anesthesiology, Pain and Perioperative Medicine, Children's National Hospital, Washington, DC, USA
| | - Fumiaki Imamura
- Department of Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Hirotaka Nishi
- Department of Obstetrics and Gynecology, Tokyo Medical University, Tokyo, Japan
| | - Keiichi Isaka
- Department of Obstetrics and Gynecology, Tokyo Medical University, Tokyo, Japan
| | - Joshua G Corbin
- Center for Neuroscience Research, Children's Research Institute, Children's National Hospital, Washington, DC, USA.,Department of Pediatrics, Pharmacology and Physiology, School of Medicine and Health Sciences, George Washington University, Washington, DC, USA
| | - Judy S Liu
- Department of Neurology, Molecular Biology, Cell Biology, and Biochemistry, Brown University, Providence, RI, USA
| | - Yuka Imamura Kawasawa
- Department of Pharmacology, Pennsylvania State University College of Medicine, Hershey, PA, USA. .,Department of Biochemistry and Molecular Biology, Institute for Personalized Medicine, Pennsylvania State University College of Medicine, Hershey, PA, USA.
| | - Masaaki Torii
- Center for Neuroscience Research, Children's Research Institute, Children's National Hospital, Washington, DC, USA. .,Department of Pediatrics, Pharmacology and Physiology, School of Medicine and Health Sciences, George Washington University, Washington, DC, USA.
| | - Kazue Hashimoto-Torii
- Center for Neuroscience Research, Children's Research Institute, Children's National Hospital, Washington, DC, USA. .,Department of Pediatrics, Pharmacology and Physiology, School of Medicine and Health Sciences, George Washington University, Washington, DC, USA.
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17
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Poppi LA, Holt JC, Lim R, Brichta AM. A review of efferent cholinergic synaptic transmission in the vestibular periphery and its functional implications. J Neurophysiol 2019; 123:608-629. [PMID: 31800345 DOI: 10.1152/jn.00053.2019] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
It has been over 60 years since peripheral efferent vestibular terminals were first identified in mammals, and yet the function of the efferent vestibular system remains obscure. One reason for the lack of progress may be due to our deficient understanding of the peripheral efferent synapse. Although vestibular efferent terminals were identified as cholinergic less than a decade after their anatomical characterization, the cellular mechanisms that underlie the properties of these synapses have had to be inferred. In this review we examine how recent mammalian studies have begun to reveal both nicotinic and muscarinic effects at these terminals and therefore provide a context for fast and slow responses observed in classic electrophysiological studies of the mammalian efferent vestibular system, nearly 40 years ago. Although incomplete, these new results together with those of recent behavioral studies are helping to unravel the mysterious and perplexing action of the efferent vestibular system. Armed with this information, we may finally appreciate the behavioral framework in which the efferent vestibular system operates.
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Affiliation(s)
- L A Poppi
- School of Biomedical Sciences and Pharmacy, The University of Newcastle, Newcastle, NSW, Australia.,Hunter Medical Research Institute, New Lambton Heights, NSW, Australia.,Preclinical Neurobiology Research Group, The University of Newcastle, Newcastle, NSW, Australia
| | - J C Holt
- Department of Otolaryngology, University of Rochester Medical Center, Rochester, New York
| | - R Lim
- School of Biomedical Sciences and Pharmacy, The University of Newcastle, Newcastle, NSW, Australia.,Hunter Medical Research Institute, New Lambton Heights, NSW, Australia.,Preclinical Neurobiology Research Group, The University of Newcastle, Newcastle, NSW, Australia
| | - A M Brichta
- School of Biomedical Sciences and Pharmacy, The University of Newcastle, Newcastle, NSW, Australia.,Hunter Medical Research Institute, New Lambton Heights, NSW, Australia.,Preclinical Neurobiology Research Group, The University of Newcastle, Newcastle, NSW, Australia
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18
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Castañeda MS, Tonini R, Richards CD, Stocker M, Pedarzani P. Benzamil inhibits neuronal and heterologously expressed small conductance Ca2+-activated K+ channels. Neuropharmacology 2019; 158:107738. [DOI: 10.1016/j.neuropharm.2019.107738] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 07/10/2019] [Accepted: 08/07/2019] [Indexed: 10/26/2022]
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19
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Brown BM, Shim H, Christophersen P, Wulff H. Pharmacology of Small- and Intermediate-Conductance Calcium-Activated Potassium Channels. Annu Rev Pharmacol Toxicol 2019; 60:219-240. [PMID: 31337271 DOI: 10.1146/annurev-pharmtox-010919-023420] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The three small-conductance calcium-activated potassium (KCa2) channels and the related intermediate-conductance KCa3.1 channel are voltage-independent K+ channels that mediate calcium-induced membrane hyperpolarization. When intracellular calcium increases in the channel vicinity, it calcifies the flexible N lobe of the channel-bound calmodulin, which then swings over to the S4-S5 linker and opens the channel. KCa2 and KCa3.1 channels are highly druggable and offer multiple binding sites for venom peptides and small-molecule blockers as well as for positive- and negative-gating modulators. In this review, we briefly summarize the physiological role of KCa channels and then discuss the pharmacophores and the mechanism of action of the most commonly used peptidic and small-molecule KCa2 and KCa3.1 modulators. Finally, we describe the progress that has been made in advancing KCa3.1 blockers and KCa2.2 negative- and positive-gating modulators toward the clinic for neurological and cardiovascular diseases and discuss the remaining challenges.
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Affiliation(s)
- Brandon M Brown
- Department of Pharmacology, University of California, Davis, California 95616, USA;
| | - Heesung Shim
- Department of Pharmacology, University of California, Davis, California 95616, USA;
| | | | - Heike Wulff
- Department of Pharmacology, University of California, Davis, California 95616, USA;
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20
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Bajaj S, Han J. Venom-Derived Peptide Modulators of Cation-Selective Channels: Friend, Foe or Frenemy. Front Pharmacol 2019; 10:58. [PMID: 30863305 PMCID: PMC6399158 DOI: 10.3389/fphar.2019.00058] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2018] [Accepted: 01/18/2019] [Indexed: 01/31/2023] Open
Abstract
Ion channels play a key role in our body to regulate homeostasis and conduct electrical signals. With the help of advances in structural biology, as well as the discovery of numerous channel modulators derived from animal toxins, we are moving toward a better understanding of the function and mode of action of ion channels. Their ubiquitous tissue distribution and the physiological relevancies of their opening and closing suggest that cation channels are particularly attractive drug targets, and years of research has revealed a variety of natural toxins that bind to these channels and alter their function. In this review, we provide an introductory overview of the major cation ion channels: potassium channels, sodium channels and calcium channels, describe their venom-derived peptide modulators, and how these peptides provide great research and therapeutic value to both basic and translational medical research.
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Affiliation(s)
- Saumya Bajaj
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
| | - Jingyao Han
- Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore, Singapore
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21
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Voos P, Fuck S, Weipert F, Babel L, Tandl D, Meckel T, Hehlgans S, Fournier C, Moroni A, Rödel F, Thiel G. Ionizing Radiation Induces Morphological Changes and Immunological Modulation of Jurkat Cells. Front Immunol 2018; 9:922. [PMID: 29760710 PMCID: PMC5936756 DOI: 10.3389/fimmu.2018.00922] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 04/13/2018] [Indexed: 12/22/2022] Open
Abstract
Impairment or stimulation of the immune system by ionizing radiation (IR) impacts on immune surveillance of tumor cells and non-malignant cells and can either foster therapy response or side effects/toxicities of radiation therapy. For a better understanding of the mechanisms by which IR modulates T-cell activation and alters functional properties of these immune cells, we exposed human immortalized Jurkat cells and peripheral blood lymphocytes (PBL) to X-ray doses between 0.1 and 5 Gy. This resulted in cellular responses, which are typically observed also in naïve T-lymphocytes in response of T-cell receptor immune stimulation or mitogens. These responses include oscillations of cytosolic Ca2+, an upregulation of CD25 surface expression, interleukin-2 and interferon-γ synthesis, elevated expression of Ca2+ sensitive K+ channels and an increase in cell diameter. The latter was sensitive to inhibition by the immunosuppressant cyclosporine A, Ca2+ buffer BAPTA-AM, and the CDK1-inhibitor RO3306, indicating the involvement of Ca2+-dependent immune activation and radiation-induced cell cycle arrest. Furthermore, on a functional level, Jurkat and PBL cell adhesion to endothelial cells was increased upon radiation exposure and was highly dependent on an upregulation of integrin beta-1 expression and clustering. In conclusion, we here report that IR impacts on immune activation and functional properties of T-lymphocytes that may have implications in both toxic effects and treatment response to combined radiation and immune therapy in cancer patients.
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Affiliation(s)
- Patrick Voos
- Department of Biology, Membrane Biophysics, Technische Universität Darmstadt, Darmstadt, Germany
| | - Sebastian Fuck
- Department of Biology, Membrane Biophysics, Technische Universität Darmstadt, Darmstadt, Germany
| | - Fabian Weipert
- Department of Radiotherapy and Oncology, Goethe-University, Frankfurt am Main, Germany
| | - Laura Babel
- Department of Biology, Membrane Biophysics, Technische Universität Darmstadt, Darmstadt, Germany
| | - Dominique Tandl
- Department of Biology, Membrane Biophysics, Technische Universität Darmstadt, Darmstadt, Germany
| | - Tobias Meckel
- Department of Biology, Membrane Biophysics, Technische Universität Darmstadt, Darmstadt, Germany
| | - Stephanie Hehlgans
- Department of Radiotherapy and Oncology, Goethe-University, Frankfurt am Main, Germany
| | - Claudia Fournier
- Department of Biophysics, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany
| | - Anna Moroni
- Department of Biosciences and CNR IBF-Mi, Università degli Studi di Milano, Milano, Italy
| | - Franz Rödel
- Department of Radiotherapy and Oncology, Goethe-University, Frankfurt am Main, Germany
| | - Gerhard Thiel
- Department of Biology, Membrane Biophysics, Technische Universität Darmstadt, Darmstadt, Germany
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22
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Honrath B, Krabbendam IE, Culmsee C, Dolga AM. Small conductance Ca 2+-activated K + channels in the plasma membrane, mitochondria and the ER: Pharmacology and implications in neuronal diseases. Neurochem Int 2017; 109:13-23. [PMID: 28511953 DOI: 10.1016/j.neuint.2017.05.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 04/24/2017] [Accepted: 05/08/2017] [Indexed: 12/14/2022]
Abstract
Ca2+-activated K+ (KCa) channels regulate after-hyperpolarization in many types of neurons in the central and peripheral nervous system. Small conductance Ca2+-activated K+ (KCa2/SK) channels, a subfamily of KCa channels, are widely expressed in the nervous system, and in the cardiovascular system. Voltage-independent SK channels are activated by alterations in intracellular Ca2+ ([Ca2+]i) which facilitates the opening of these channels through binding of Ca2+ to calmodulin that is constitutively bound to the SK2 C-terminus. In neurons, SK channels regulate synaptic plasticity and [Ca2+]i homeostasis, and a number of recent studies elaborated on the emerging neuroprotective potential of SK channel activation in conditions of excitotoxicity and cerebral ischemia, as well as endoplasmic reticulum (ER) stress and oxidative cell death. Recently, SK channels were discovered in the inner mitochondrial membrane and in the membrane of the endoplasmic reticulum which sheds new light on the underlying molecular mechanisms and pathways involved in SK channel-mediated protective effects. In this review, we will discuss the protective properties of pharmacological SK channel modulation with particular emphasis on intracellularly located SK channels as potential therapeutic targets in paradigms of neuronal dysfunction.
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Affiliation(s)
- Birgit Honrath
- Institute of Pharmacology and Clinical Pharmacy, University of Marburg, 35043 Marburg, Germany; Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, Department of Molecular Pharmacology, University of Groningen, 9713 AV Groningen, The Netherlands
| | - Inge E Krabbendam
- Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, Department of Molecular Pharmacology, University of Groningen, 9713 AV Groningen, The Netherlands
| | - Carsten Culmsee
- Institute of Pharmacology and Clinical Pharmacy, University of Marburg, 35043 Marburg, Germany
| | - Amalia M Dolga
- Institute of Pharmacology and Clinical Pharmacy, University of Marburg, 35043 Marburg, Germany; Faculty of Science and Engineering, Groningen Research Institute of Pharmacy, Department of Molecular Pharmacology, University of Groningen, 9713 AV Groningen, The Netherlands.
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23
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Voos P, Yazar M, Lautenschläger R, Rauh O, Moroni A, Thiel G. The small neurotoxin apamin blocks not only small conductance Ca 2+ activated K + channels (SK type) but also the voltage dependent Kv1.3 channel. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2017; 46:517-523. [PMID: 28108814 DOI: 10.1007/s00249-016-1196-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 12/12/2016] [Accepted: 12/30/2016] [Indexed: 11/29/2022]
Abstract
Apamin is frequently used as a specific blocker of small-conductance Ca2+-activated (SK type) K+ channels. Here we show that the small neurotoxin is not as specific as anticipated. It is also a high-affinity inhibitor with an IC50 of 13 nM of the Kv1.3 channel; it blocks the latter with potency similar to the Kv1.3 blocker PAP-1. Since SK type channels and Kv1.3 channels are frequently coexpressed in different tissues such as cells of the immune system, apamin must be used with caution as a pharmacological tool.
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Affiliation(s)
- Patrick Voos
- Department of Biology, Plant Membrane Biophysics, Technische Universität Darmstadt, Schnittspahnstrasse 3, 64287, Darmstadt, Germany
| | - Mehtap Yazar
- Department of Biology, Plant Membrane Biophysics, Technische Universität Darmstadt, Schnittspahnstrasse 3, 64287, Darmstadt, Germany
| | - René Lautenschläger
- Department of Biology, Plant Membrane Biophysics, Technische Universität Darmstadt, Schnittspahnstrasse 3, 64287, Darmstadt, Germany
| | - Oliver Rauh
- Department of Biology, Plant Membrane Biophysics, Technische Universität Darmstadt, Schnittspahnstrasse 3, 64287, Darmstadt, Germany
| | - Anna Moroni
- Department of Biology and CNR IBF-Mi, Università degli Studi di Milano, Milan, Italy
| | - Gerhard Thiel
- Department of Biology, Plant Membrane Biophysics, Technische Universität Darmstadt, Schnittspahnstrasse 3, 64287, Darmstadt, Germany.
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24
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Singh SK, Deshpande SB. B1-kinin receptors modulate Mesobuthus tamulus venom-induced vasosensory reflex responses in anesthetized rats. Indian J Pharmacol 2016; 48:388-393. [PMID: 27756949 PMCID: PMC4980926 DOI: 10.4103/0253-7613.186202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
OBJECTIVE Intra-arterial injection of Mesobuthus tamulus (BT) venom produces reflex vasosensory responses modulating cardiorespiratory parameters in albino rats. The present study was conducted to understand the role of kinin receptors in modulating vasosensory reflexes evoked by BT venom. MATERIALS AND METHODS In urethane-anesthetized rats, tracheostomy was performed to keep the airway patent. The femoral artery was cannulated proximally, as well as distally, to record the blood pressure (BP) and to inject the chemicals, respectively. Electrocardiographic and respiratory excursions were recorded to compute the heart rate (HR) and respiratory rate (RR). A group of animals was pretreated with saline/kinin receptor antagonists intra-arterially (B1/B2 receptor antagonists) before the injection of venom. RESULTS After intra-arterial injection of BT venom (1 mg/kg), there was an immediate increase in RR, which reached to 40% within 30 s, followed by a decrease of 40%. Further, there was sustained increase in RR (50%) up to 60 min. The BP started to increase at 40 s, peaking at 5 min (50%), and remained above the initial level up to 60 min. The bradycardiac response started after 5 min which peaked (50% of initial) at 25 min and remained at that level up to 60 min. In B1 receptor antagonist (des-Arg) pretreated animals, venom-induced cardiovascular responses were attenuated (by 20-25% in mean arterial pressure and HR) significantly but not in B2 receptor antagonist (Hoe-140) pretreated animals. Either of the antagonists failed to alter the RR responses. CONCLUSIONS BT venom-induced vasosensory reflex responses modulating cardiovascular parameters are mediated via B1-kinin receptors in anesthetized rats.
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Affiliation(s)
- Sanjeev K Singh
- Department of Physiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India
| | - Shripad B Deshpande
- Department of Physiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India
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25
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Housley DM, Housley GD, Liddell MJ, Jennings EA. Scorpion toxin peptide action at the ion channel subunit level. Neuropharmacology 2016; 127:46-78. [PMID: 27729239 DOI: 10.1016/j.neuropharm.2016.10.004] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Revised: 09/06/2016] [Accepted: 10/06/2016] [Indexed: 12/19/2022]
Abstract
This review categorizes functionally validated actions of defined scorpion toxin (SCTX) neuropeptides across ion channel subclasses, highlighting key trends in this rapidly evolving field. Scorpion envenomation is a common event in many tropical and subtropical countries, with neuropharmacological actions, particularly autonomic nervous system modulation, causing significant mortality. The primary active agents within scorpion venoms are a diverse group of small neuropeptides that elicit specific potent actions across a wide range of ion channel classes. The identification and functional characterisation of these SCTX peptides has tremendous potential for development of novel pharmaceuticals that advance knowledge of ion channels and establish lead compounds for treatment of excitable tissue disorders. This review delineates the unique specificities of 320 individual SCTX peptides that collectively act on 41 ion channel subclasses. Thus the SCTX research field has significant translational implications for pathophysiology spanning neurotransmission, neurohumoral signalling, sensori-motor systems and excitation-contraction coupling. This article is part of the Special Issue entitled 'Venom-derived Peptides as Pharmacological Tools.'
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Affiliation(s)
- David M Housley
- College of Medicine and Dentistry, Cairns Campus, James Cook University, Cairns, Queensland 4878, Australia; Translational Neuroscience Facility and Department of Physiology, School of Medical Sciences, UNSW Australia, Sydney, NSW 2052, Australia.
| | - Gary D Housley
- Translational Neuroscience Facility and Department of Physiology, School of Medical Sciences, UNSW Australia, Sydney, NSW 2052, Australia
| | - Michael J Liddell
- Centre for Tropical Environmental and Sustainability Science and College of Science & Engineering, Cairns Campus, James Cook University, Cairns, Queensland 4878, Australia
| | - Ernest A Jennings
- College of Medicine and Dentistry, Cairns Campus, James Cook University, Cairns, Queensland 4878, Australia; Centre for Biodiscovery and Molecular Development of Therapeutics, James Cook University, Queensland 4878, Australia; Australian Institute of Tropical Health and Medicine, James Cook University, Cairns Campus, QLD, Australia
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26
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Abstract
Small-conductance Ca2+-activated potassium (SK) channels are relative newcomers within the field of cardiac electrophysiology. In recent years, an increased focus has been given to these channels because they might constitute a relatively atrial-selective target. This review will give a general introduction to SK channels followed by their proposed function in the heart under normal and pathophysiological conditions. It is revealed how antiarrhythmic effects can be obtained by SK channel inhibition in a number of species in situations of atrial fibrillation. On the contrary, the beneficial effects of SK channel inhibition in situations of heart failure are questionable and still needs investigation. The understanding of cardiac SK channels is rapidly increasing these years, and it is hoped that this will clarify whether SK channel inhibition has potential as a new anti–atrial fibrillation principle.
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27
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28
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Kuzmenkov AI, Grishin EV, Vassilevski AA. Diversity of Potassium Channel Ligands: Focus on Scorpion Toxins. BIOCHEMISTRY (MOSCOW) 2016; 80:1764-99. [DOI: 10.1134/s0006297915130118] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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29
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Abstract
Scorpion envenomations are ubiquitous, but nephropathy is a rare manifestation, reported mainly from the Middle East and North Africa. Rapid venom redistribution from blood, delayed excretion from the kidneys, direct toxicity of venom enzymes, cytokine release and afferent arteriolar constriction have been seen in experimental animals. Haemoglobinuria, acute tubular necrosis, interstitial nephritis and haemolytic–uraemic syndrome have been documented in human victims of scorpion envenomation. Epidemiology, venom components and toxins, effects on the laboratory mammals especially the kidneys and reports of renal failure in humans are reviewed in this article.
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Affiliation(s)
- Stalin Viswanathan
- Department of Internal Medicine, Pondicherry Institute of Medical Sciences, Kalapet, Pondicherry, India
| | - Chaitanya Prabhu
- Department of Nephrology, Pondicherry Institute of Medical Sciences, Kalapet, Pondicherry, India
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SK channels and ventricular arrhythmias in heart failure. Trends Cardiovasc Med 2015; 25:508-14. [PMID: 25743622 DOI: 10.1016/j.tcm.2015.01.010] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2014] [Revised: 01/19/2015] [Accepted: 01/20/2015] [Indexed: 12/18/2022]
Abstract
Small-conductance Ca(2+)-activated K(+) (SK) currents are important in the repolarization of normal atrial (but not ventricular) cardiomyocytes. However, recent studies showed that the SK currents are upregulated in failing ventricular cardiomyocytes, along with increased SK channel protein expression and enhanced sensitivity to intracellular Ca(2+). The SK channel activation may be either anti-arrhythmic or pro-arrhythmic, depending on the underlying clinical situations. While the SK channel is a new target of anti-arrhythmic therapy, drug safety is still one of the major concerns.
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Badarau E, Dilly S, Wouters J, Seutin V, Liégeois JF. Chemical modifications of the N -methyl-laudanosine scaffold point to new directions for SK channels exploration. Bioorg Med Chem Lett 2014; 24:5616-5620. [DOI: 10.1016/j.bmcl.2014.10.083] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 10/24/2014] [Accepted: 10/27/2014] [Indexed: 01/19/2023]
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Siddiqui T, Lively S, Ferreira R, Wong R, Schlichter LC. Expression and contributions of TRPM7 and KCa2.3/SK3 channels to the increased migration and invasion of microglia in anti-inflammatory activation states. PLoS One 2014; 9:e106087. [PMID: 25148577 PMCID: PMC4141841 DOI: 10.1371/journal.pone.0106087] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Accepted: 07/31/2014] [Indexed: 01/17/2023] Open
Abstract
Microglia rapidly respond to CNS injury and disease and can assume a spectrum of activation states. While changes in gene expression and production of inflammatory mediators have been extensively described after classical (LPS-induced) and alternative (IL4-induced) microglial activation, less is known about acquired de-activation in response to IL10. It is important to understand how microglial activation states affect their migration and invasion; crucial functions after injury and in the developing CNS. We reported that LPS-treated rat microglia migrate very poorly, while IL4-treated cells migrate and invade much better. Having discovered that the lamellum of migrating microglia contains a large ring of podosomes – microscopic structures that are thought to mediate adhesion, migration and invasion – we hypothesized that IL4 and IL10 would differentially affect podosome expression, gene induction, migration and invasion. Further, based on the enrichment of the KCa2.3/SK3 Ca2+-activated potassium channel in microglial podosomes, we predicted that it regulates migration and invasion. We found both similarities and differences in gene induction by IL4 and IL10 and, while both cytokines increased migration and invasion, only IL10 affected podosome expression. KCa2.3 currents were recorded in microglia under all three activation conditions and KCNN3 (KCa2.3) expression was similar. Surprisingly then, of three KCa2.3 inhibitors (apamin, tamapin, NS8593), only NS8593 abrogated the increased migration and invasion of IL4 and IL10-treated microglia (and invasion of unstimulated microglia). This discrepancy was explained by the observed block of TRPM7 currents in microglia by NS8593, which occurred under all three activation conditions. A similar inhibition of both migration and invasion was seen with a TRPM7 inhibitor (AA-861) that does not block KCa2.3 channels. Thus, we conclude that TRPM7 (not KCa2.3) contributes to the enhanced ability of microglia to migrate and invade when in anti-inflammatory states. This will be an important consideration in developing TRPM7 inhibitors for treating CNS injury.
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Affiliation(s)
- Tamjeed Siddiqui
- Toronto Western Research Institute, Genes and Development Division, University Health Network, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Starlee Lively
- Toronto Western Research Institute, Genes and Development Division, University Health Network, Toronto, Ontario, Canada
| | - Roger Ferreira
- Toronto Western Research Institute, Genes and Development Division, University Health Network, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Raymond Wong
- Toronto Western Research Institute, Genes and Development Division, University Health Network, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
| | - Lyanne C. Schlichter
- Toronto Western Research Institute, Genes and Development Division, University Health Network, Toronto, Ontario, Canada
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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Ramírez-Cordero B, Toledano Y, Cano-Sánchez P, Hernández-López R, Flores-Solis D, Saucedo-Yáñez AL, Chávez-Uribe I, Brieba LG, del Río-Portilla F. Cytotoxicity of recombinant tamapin and related toxin-like peptides on model cell lines. Chem Res Toxicol 2014; 27:960-7. [PMID: 24821061 DOI: 10.1021/tx4004193] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The scorpion toxin tamapin displays the most potent and selective blockage against KCa2.2 channels known to date. In this work, we report the biosynthesis, three-dimensional structure, and cytotoxicity on cancer cell lines (Jurkat E6-1 and human mammary breast cancer MDA-MB-231) of recombinant tamapin and five related peptides bearing mutations on residues (R6A,R7A, R13A, R6A-R7A, and GS-tamapin) that were previously suggested to be important for tamapin's activity. The indicated cell lines were used as they constitutively express KCa2.2 channels. The studied toxin-like peptides displayed lethal responses on Jurkat T cells and breast cancer cells; their effect is dose- and time-dependent with IC50 values in the nanomolar range. The order of potency is r-tamapin>GS-tamapin>R6A>R13A>R6A-R7A>R7A for Jurkat T cells and r-tamapin>R7A for MDA-MB-231 breast cancer cells. Our structural determination by NMR demonstrated that r-tamapin preserves the folding of the αKTx5 subfamily and that neither single nor double alanine mutations affect the three-dimensional structure of the wild-type peptide. In contrast, our activity assays show that changes in cytotoxicity are related to the chemical nature of certain residues. Our results suggest that the toxic activity of r-tamapin on Jurkat and breast cancer cells could be mediated by the interaction of charged residues in tamapin with KCa2.2 channels via the apoptotic cell death pathway.
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Affiliation(s)
- Belén Ramírez-Cordero
- Instituto de Química, Universidad Nacional Autónoma de México , Ciudad Universitaria, Circuito Exterior s/n, México, D.F. 04510, México
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Alix P, Venkatesan K, Scuvée-Moreau J, Massotte L, Nguyen Trung ML, Cornil CA, Seutin V. Mechanism of the medium-duration afterhyperpolarization in rat serotonergic neurons. Eur J Neurosci 2013; 39:186-96. [PMID: 24188044 DOI: 10.1111/ejn.12408] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Revised: 09/27/2013] [Accepted: 10/04/2013] [Indexed: 11/28/2022]
Abstract
Most serotonergic neurons display a prominent medium-duration afterhyperpolarization (mAHP), which is mediated by small-conductance Ca(2+) -activated K(+) (SK) channels. Recent ex vivo and in vivo experiments have suggested that SK channel blockade increases the firing rate and/or bursting in these neurons. The purpose of this study was therefore to characterize the source of Ca(2+) which activates the mAHP channels in serotonergic neurons. In voltage-clamp experiments, an outward current was recorded at -60 mV after a depolarizing pulse to +100 mV. A supramaximal concentration of the SK channel blockers apamin or (-)-bicuculline methiodide blocked this outward current. This current was also sensitive to the broad Ca(2+) channel blocker Co(2+) and was partially blocked by both ω-conotoxin and mibefradil, which are blockers of N-type and T-type Ca(2+) channels, respectively. Neither blockers of other voltage-gated Ca(2+) channels nor DBHQ, an inhibitor of Ca(2+)-induced Ca(2+) release, had any effect on the SK current. In current-clamp experiments, mAHPs following action potentials were only blocked by ω-conotoxin and were unaffected by mibefradil. This was observed in slices from both juvenile and adult rats. Finally, when these neurons were induced to fire in an in vivo-like pacemaker rate, only ω-conotoxin was able to increase their firing rate (by ~30%), an effect identical to the one previously reported for apamin. Our results demonstrate that N-type Ca(2+) channels are the only source of Ca(2+) which activates the SK channels underlying the mAHP. T-type Ca(2+) channels may also activate SK channels under different circumstances.
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Affiliation(s)
- Philippe Alix
- Neurophysiology Unit, GIGA Neurosciences, University of Liège, Liège, Belgium
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Lam J, Coleman N, Garing ALA, Wulff H. The therapeutic potential of small-conductance KCa2 channels in neurodegenerative and psychiatric diseases. Expert Opin Ther Targets 2013; 17:1203-20. [PMID: 23883298 DOI: 10.1517/14728222.2013.823161] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
INTRODUCTION KCa2 or small-conductance Ca(2+)-activated K(+) channels (SK) are expressed in many areas of the central nervous system where they participate in the regulation of neuronal afterhyperpolarization and excitability, and also serve as negative feedback regulators on the glutamate-NMDA pathway. AREAS COVERED This review focuses on the role of KCa2 channels in learning and memory and their potential as therapeutic targets for Alzheimer's and Parkinson's disease, ataxia, schizophrenia and alcohol dependence. EXPERT OPINION There currently exists relatively solid evidence supporting the use of KCa2 activators for ataxia. Genetic KCa2 channel suppression in deep cerebellar neurons induces ataxia, while KCa2 activators like 1-EBIO, SKA-31 and NS13001 improve motor deficits in mouse models of episodic ataxia (EA) and spinal cerebellar ataxia (SCA). Use of KCa2 activators for ataxia is further supported by a report that riluzole improves ataxia in a small clinical trial. Based on accumulating literature evidence, KCa2 activators further appear attractive for the treatment of alcohol dependence and withdrawal. Regarding Alzheimer's disease, Parkinson's disease and schizophrenia, further research, including long-term studies in disease relevant animal models, will be needed to determine whether KCa2 channels constitute valid targets and whether activators or inhibitors would be needed to positively affect disease outcomes.
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Affiliation(s)
- Jenny Lam
- University of California, Davis, Department of Pharmacology , 451 Health Sciences Drive, Genome and Biomedical Sciences Facility Room 3502, Davis, CA 95616 , USA +1 530 754 6135 ; +1 530 752 7710 ;
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The interactions of apamin and tetraethylammonium are differentially affected by single mutations in the pore mouth of small conductance calcium-activated potassium (SK) channels. Biochem Pharmacol 2013; 85:560-9. [DOI: 10.1016/j.bcp.2012.12.015] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2012] [Revised: 12/14/2012] [Accepted: 12/17/2012] [Indexed: 10/27/2022]
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Chubanov V, Mederos y Schnitzler M, Meißner M, Schäfer S, Abstiens K, Hofmann T, Gudermann T. Natural and synthetic modulators of SK (K(ca)2) potassium channels inhibit magnesium-dependent activity of the kinase-coupled cation channel TRPM7. Br J Pharmacol 2012; 166:1357-76. [PMID: 22242975 DOI: 10.1111/j.1476-5381.2012.01855.x] [Citation(s) in RCA: 111] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND AND PURPOSE Transient receptor potential cation channel subfamily M member 7 (TRPM7) is a bifunctional protein comprising a TRP ion channel segment linked to an α-type protein kinase domain. TRPM7 is essential for proliferation and cell growth. Up-regulation of TRPM7 function is involved in anoxic neuronal death, cardiac fibrosis and tumour cell proliferation. The goal of this work was to identify non-toxic inhibitors of the TRPM7 channel and to assess the effect of blocking endogenous TRPM7 currents on the phenotype of living cells. EXPERIMENTAL APPROACH We developed an aequorin bioluminescence-based assay of TRPM7 channel activity and performed a hypothesis-driven screen for inhibitors of the channel. The candidates identified were further assessed electrophysiologically and in cell biological experiments. KEY RESULTS TRPM7 currents were inhibited by modulators of small conductance Ca²⁺ -activated K⁺ channels (K(Ca)2.1-2.3; SK) channels, including the antimalarial plant alkaloid quinine, CyPPA, dequalinium, NS8593, SKA31 and UCL 1684. The most potent compound NS8593 (IC₅₀ 1.6 µM) specifically targeted TRPM7 as compared with other TRP channels, interfered with Mg²⁺ -dependent regulation of TRPM7 channel and inhibited the motility of cultured cells. NS8593 exhibited full and reversible block of native TRPM7-like currents in HEK 293 cells, freshly isolated smooth muscle cells, primary podocytes and ventricular myocytes. CONCLUSIONS AND IMPLICATIONS This study reveals a tight overlap in the pharmacological profiles of TRPM7 and K(Ca)2.1-2.3 channels. NS8593 acts as a negative gating modulator of TRPM7 and is well-suited to study functional features and cellular roles of endogenous TRPM7.
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Affiliation(s)
- V Chubanov
- Walther-Straub-Institute of Pharmacology and Toxicology, University of Munich, Munich, Germany.
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Dolga AM, Letsche T, Gold M, Doti N, Bacher M, Chiamvimonvat N, Dodel R, Culmsee C. Activation of KCNN3/SK3/K(Ca)2.3 channels attenuates enhanced calcium influx and inflammatory cytokine production in activated microglia. Glia 2012; 60:2050-64. [PMID: 23002008 DOI: 10.1002/glia.22419] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Accepted: 08/23/2012] [Indexed: 11/10/2022]
Abstract
In neurons, small-conductance calcium-activated potassium (KCNN/SK/K(Ca)2) channels maintain calcium homeostasis after N-methyl-D-aspartate (NMDA) receptor activation, thereby preventing excitotoxic neuronal death. So far, little is known about the function of KCNN/SK/K(Ca)2 channels in non-neuronal cells, such as microglial cells. In this study, we addressed the question whether KCNN/SK/K(Ca)2 channels activation affected inflammatory responses of primary mouse microglial cells upon lipopolysaccharide (LPS) stimulation. We found that N-cyclohexyl-N-[2-(3,5-dimethyl-pyrazol-1-yl)-6-methyl-4-pyrimidinamine (CyPPA), a positive pharmacological activator of KCNN/SK/K(Ca)2 channels, significantly reduced LPS-stimulated activation of microglia in a concentration-dependent manner. The general KCNN/SK/K(Ca)2 channel blocker apamin reverted these effects of CyPPA on microglial proliferation. Since calcium plays a central role in microglial activation, we further addressed whether KCNN/SK/K(Ca)2 channel activation affected the changes of intracellular calcium levels, [Ca(2+)](i), in microglial cells. Our data show that LPS-induced elevation of [Ca(2+)](i) was attenuated following activation of KCNN2/3/K(Ca)2.2/K(Ca)2.3 channels by CyPPA. Furthermore, CyPPA reduced downstream events including tumor necrosis factor alpha and interleukin 6 cytokine production and nitric oxide release in activated microglia. Further, we applied specific peptide inhibitors of the KCNN/SK/K(Ca)2 channel subtypes to identify which particular channel subtype mediated the observed anti-inflammatory effects. Only inhibitory peptides targeting KCNN3/SK3/K(Ca)2.3 channels, but not KCNN2/SK2/K(Ca)2.2 channel inhibition, reversed the CyPPA-effects on LPS-induced microglial proliferation. These findings revealed that KCNN3/SK3/K(Ca)2.3 channels can modulate the LPS-induced inflammatory responses in microglial cells. Thus, KCNN3/SK3/K(Ca)2.3 channels may serve as a therapeutic target for reducing microglial activity and related inflammatory responses in the central nervous system.
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Affiliation(s)
- Amalia M Dolga
- Institute of Pharmacology and Clinical Pharmacy, Philipps University of Marburg, 35032, Marburg, Germany.
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Towards therapeutic applications of arthropod venom k(+)-channel blockers in CNS neurologic diseases involving memory acquisition and storage. J Toxicol 2012; 2012:756358. [PMID: 22701481 PMCID: PMC3373146 DOI: 10.1155/2012/756358] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Accepted: 02/08/2012] [Indexed: 12/31/2022] Open
Abstract
Potassium channels are the most heterogeneous and widely distributed group of ion channels and play important functions in all cells, in both normal and pathological mechanisms, including learning and memory processes. Being fundamental for many diverse physiological processes, K+-channels are recognized as potential therapeutic targets in the treatment of several Central Nervous System (CNS) diseases, such as multiple sclerosis, Parkinson's and Alzheimer's diseases, schizophrenia, HIV-1-associated dementia, and epilepsy. Blockers of these channels are therefore potential candidates for the symptomatic treatment of these neuropathies, through their neurological effects. Venomous animals have evolved a wide set of toxins for prey capture and defense. These compounds, mainly peptides, act on various pharmacological targets, making them an innumerable source of ligands for answering experimental paradigms, as well as for therapeutic application. This paper provides an overview of CNS K+-channels involved in memory acquisition and storage and aims at evaluating the use of highly selective K+-channel blockers derived from arthropod venoms as potential therapeutic agents for CNS diseases involving learning and memory mechanisms.
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Tiwari AK, Mandal MB, Deshpande SB. Role of serotonergic mechanism in gastric contractions induced by Indian Red Scorpion (Mesobuthus tamulus) venom. Indian J Pharmacol 2011; 41:255-7. [PMID: 20407555 PMCID: PMC2846498 DOI: 10.4103/0253-7613.59923] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2009] [Revised: 08/24/2009] [Accepted: 12/09/2009] [Indexed: 11/09/2022] Open
Abstract
Aim: Gastric dysfunctions are commonly seen after scorpion envenomation, and the underlying mechanisms are not clear. Therefore, the present study was undertaken to investigate the effect of Indian red scorpion (Mesobuthus tamulus, MBT) venom on gastric fundus muscle contraction and the underlying mechanisms involved. Materials and Methods: In vitro isometric contraction was recorded from gastric fundus muscle strips on a chart recorder. The tissue was exposed to different concentrations of serotonin or crude MBT venom. The contractile responses to venom were expressed as the percentage of maximum contraction produced by serotonin at the beginning of each experiment. The contractile responses to 1.0 μg/ml of crude MBT venom were ascertained in the absence or presence of serotonin antagonist, methysergide. Results: Serotonin produced concentration-dependent fundus contractions (0.004–4.0 μM), and maximum contractile response was observed at 4.0 μM of serotonin. Hence, the contractile response obtained at 4.0 μM of serotonin was taken for normalization. The crude MBT venom (0.1–1.0 μg/ml) produced a concentration-dependent increase in fundus contractions (as % of maximum fundus contraction produced by serotonin at 4.0 μM). The maximum response was observed at 1.0 μg/ml of crude venom and a further increase in the concentration, up to 3.0 μg/ml, did not increase the response. In a separate series of experiments, pre-treatment with methysergide (1.0 μM) significantly attenuated the contractile response elicited by the venom (1.0 μg/ml) (P<0.05) and blocked the serotonin (4.0 μM) response. Conclusion: The results suggest that the crude MBT venom produces gastric fundus contractions by partially involving serotonin.
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Affiliation(s)
- A K Tiwari
- Department of Physiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi - 221005, India
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Maurya AN, Deshpande SB. Involvement of NO-guanylyl cyclase pathway for the depression of spinal monosynaptic reflex by Mesobuthus tamulus venom in neonatal rat in vitro. Life Sci 2011; 88:886-91. [PMID: 21447347 DOI: 10.1016/j.lfs.2011.03.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2010] [Revised: 01/31/2011] [Accepted: 03/22/2011] [Indexed: 11/17/2022]
Abstract
AIMS The present study was undertaken to evaluate the role of nitric oxide (NO) in Mesobuthus tamulus (MBT) venom-induced depression of spinal reflexes. MAIN METHODS Experiments were performed on isolated hemisected spinal cords from 4 to 6day old rats. Stimulation of a dorsal root with supramaximal strength evoked monosynaptic (MSR) and polysynaptic reflex (PSR) potentials in the corresponding segmental ventral root. KEY FINDINGS Superfusion of MBT venom (0.3μg/ml) depressed the spinal reflexes in a time-dependent manner and the maximum depression was seen at 10min (MSR by 63%; PSR by 79%). The time to produce 50% depression (T-50) of MSR and PSR was 7.7±1.3 and 5.7±0.5min, respectively. Pretreatment with bicuculline (1μM; GABA(A) receptor antagonist) or strychnine (1μM; glycine(A) receptor antagonist) did not block the venom-induced depression of spinal reflexes. However, Nω-nitro-L-arginine methyl ester (L-NAME, 100 or 300μM; NO synthase inhibitor) or hemoglobin (Hb, 100μM; NO scavenger) antagonized the venom-induced depression of MSR. Further, soluble guanylyl cylase inhibitors (1H-[1,2,4]Oxadiazolo[4,3-a]quinoxalin-1-one, ODQ; 1μM or methylene blue, 100μM) also antagonized the venom-induced depression of MSR but not PSR. Nitrite concentration (indicator of NO activity) of the cords exposed to venom (0.3μg/ml) was not different from the control group. SIGNIFICANCE The results indicate that venom-induced depression of MSR is mediated via NO-guanylyl cyclase pathway without involving GABAergic or glycinergic system.
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Affiliation(s)
- Amar N Maurya
- Department of Physiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, UP, India
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Windley MJ, Escoubas P, Valenzuela SM, Nicholson GM. A Novel Family of Insect-Selective Peptide Neurotoxins Targeting Insect Large-Conductance Calcium-Activated K+ Channels Isolated from the Venom of the Theraphosid Spider Eucratoscelus constrictus. Mol Pharmacol 2011; 80:1-13. [DOI: 10.1124/mol.110.070540] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
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Weatherall KL, Goodchild SJ, Jane DE, Marrion NV. Small conductance calcium-activated potassium channels: From structure to function. Prog Neurobiol 2010; 91:242-55. [DOI: 10.1016/j.pneurobio.2010.03.002] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2009] [Revised: 03/05/2010] [Accepted: 03/24/2010] [Indexed: 10/19/2022]
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The Ca2+ activated SK3 channel is expressed in microglia in the rat striatum and contributes to microglia-mediated neurotoxicity in vitro. J Neuroinflammation 2010; 7:4. [PMID: 20074365 PMCID: PMC2819255 DOI: 10.1186/1742-2094-7-4] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2009] [Accepted: 01/14/2010] [Indexed: 12/18/2022] Open
Abstract
Background Small-conductance Ca2+ activated K+ channels are expressed in the CNS, where KCNN2/SK2/KCa2.2 and KCNN3/SK3/KCa2.3 help shape the electrical activity of some neurons. The SK3 channel is considered a potential therapeutic target for diseases and disorders involving neuron hyper-excitability but little is known about its expression and roles in non-neuronal cells in either the healthy or damaged CNS. The purpose of this study was to examine expression of KCNN3/SK3 in CNS microglia in vivo and in vitro, and to use an established in vitro model to determine if this channel contributes to the neurotoxic capacity of activated microglia. Methods KCNN3 mRNA (real-time RT-PCR) and SK3 immunoreactivity were examined in rat microglia. Lipopolysaccharide was then used to activate microglia (monitored by iNOS, nitric oxide, activation of NF-κB and p38 MAPK) and transform them to a neurotoxic state. Microglia-mediated neuron damage (TUNEL, activated caspase 3) and nitrotyrosine levels were quantified using a two-chamber system that allowed microglia to be treated with channel blockers, washed and then added to neuron/astrocyte cultures. Contributions of SK3 to these processes were discriminated using a subtractive pharmacological approach with apamin and tamapin. ANOVA and post-hoc tests were used to assess the statistical significance of differences between treatment groups. SK3 immunoreactivity was then compared in the normal and damaged adult rat striatum, by injecting collagenase (a hemorrhagic stroke) or endothelin-1 (a transient ischemic stroke). Results KCNN3 mRNA was prevalent in cultured microglia and increased after lipopolysaccharide-induced activation; SK3 channel blockade inhibited microglial activation and reduced their ability to kill neurons. SK3 immunoreactivity was prevalent in cultured microglia and throughout the adult rat striatum (except white matter tracts). After strokes, SK3 was highly expressed in activated microglia/macrophages within the lesions, but reduced in other cells. Conclusions SK3 is expressed in microglia in both the healthy and damaged adult striatum, and mechanistic in vitro studies show it contributes to transformation of microglia to an activated neurotoxic phenotype. Thus, SK3 might be a therapeutic target for reducing inflammation-mediated acute CNS damage. Moreover, its roles in microglia must be considered when targeting this channel for CNS diseases, disorders and reducing neuron hyper-excitability.
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Functions and modulation of neuronal SK channels. Cell Biochem Biophys 2009; 55:127-39. [PMID: 19655101 DOI: 10.1007/s12013-009-9062-7] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2009] [Accepted: 07/15/2009] [Indexed: 10/20/2022]
Abstract
Small conductance (SK) channels are calcium-activated potassium channels that, when cloned in 1996, were thought solely to contribute to the afterhyperpolarisation that follows action potentials, and to control repetitive firing patterns of neurons. However, discoveries over the past few years have identified novel roles for SK channels in controlling dendritic excitability, synaptic transmission and synaptic plasticity. More recently, modulation of SK channel calcium sensitivity by casein kinase 2, and of SK channel trafficking by protein kinase A, have been demonstrated. This article will discuss recent findings regarding the function and modulation of SK channels in central neurons.
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Félétou M. Calcium-activated potassium channels and endothelial dysfunction: therapeutic options? Br J Pharmacol 2009; 156:545-62. [PMID: 19187341 DOI: 10.1111/j.1476-5381.2009.00052.x] [Citation(s) in RCA: 191] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
The three subtypes of calcium-activated potassium channels (K(Ca)) of large, intermediate and small conductance (BK(Ca), IK(Ca) and SK(Ca)) are present in the vascular wall. In healthy arteries, BK(Ca) channels are preferentially expressed in vascular smooth muscle cells, while IK(Ca) and SK(Ca) are preferentially located in endothelial cells. The activation of endothelial IK(Ca) and SK(Ca) contributes to nitric oxide (NO) generation and is required to elicit endothelium-dependent hyperpolarizations. In the latter responses, the hyperpolarization of the smooth muscle cells is evoked either via electrical coupling through myo-endothelial gap junctions or by potassium ions, which by accumulating in the intercellular space activate the inwardly rectifying potassium channel Kir2.1 and/or the Na(+)/K(+)-ATPase. Additionally, endothelium-derived factors such as cytochrome P450-derived epoxyeicosatrienoic acids and under some circumstances NO, prostacyclin, lipoxygenase products and hydrogen peroxide (H(2)O(2)) hyperpolarize and relax the underlying smooth muscle cells by activating BK(Ca). In contrast, cytochrome P450-derived 20-hydroxyeicosatetraenoic acid and various endothelium-derived contracting factors inhibit BK(Ca). Aging and cardiovascular diseases are associated with endothelial dysfunctions that can involve a decrease in NO bioavailability, alterations of EDHF-mediated responses and/or enhanced production of endothelium-derived contracting factors. Because potassium channels are involved in these endothelium-dependent responses, activation of endothelial and/or smooth muscle K(Ca) could prevent the occurrence of endothelial dysfunction. Therefore, direct activators of these potassium channels or compounds that regulate their activity or their expression may be of some therapeutic interest. Conversely, blockers of IK(Ca) may prevent restenosis and that of BK(Ca) channels sepsis-dependent hypotension.
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Affiliation(s)
- Michel Félétou
- Department of Angiology, Institut de Recherches Servier, Suresnes, France.
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Molecular and cellular basis of small--and intermediate-conductance, calcium-activated potassium channel function in the brain. Cell Mol Life Sci 2008; 65:3196-217. [PMID: 18597044 PMCID: PMC2798969 DOI: 10.1007/s00018-008-8216-x] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Small conductance calcium-activated potassium (SK or KCa2) channels link intracellular calcium transients to membrane potential changes. SK channel subtypes present different pharmacology and distribution in the nervous system. The selective blocker apamin, SK enhancers and mice lacking specific SK channel subunits have revealed multifaceted functions of these channels in neurons, glia and cerebral blood vessels. SK channels regulate neuronal firing by contributing to the afterhyperpolarization following action potentials and mediating IAHP, and partake in a calcium-mediated feedback loop with NMDA receptors, controlling the threshold for induction of hippocampal long-term potentiation. The function of distinct SK channel subtypes in different neurons often results from their specific coupling to different calcium sources. The prominent role of SK channels in the modulation of excitability and synaptic function of limbic, dopaminergic and cerebellar neurons hints at their possible involvement in neuronal dysfunction, either as part of the causal mechanism or as potential therapeutic targets.
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48
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Kanoo S, Mandal MB, Alex AB, Deshpande SB. Cardiac dysrhythmia produced by Mesobuthus tamulus venom involves NO-dependent G-Cyclase signaling pathway. Naunyn Schmiedebergs Arch Pharmacol 2008; 379:525-32. [PMID: 19037630 DOI: 10.1007/s00210-008-0375-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2008] [Accepted: 11/06/2008] [Indexed: 11/29/2022]
Abstract
Role of G-protein coupled pathways in modulating the cardiotoxic effects produced by Indian red scorpion (Mesobuthus tamulus) venom were examined. The isometric contractions of spontaneously beating or paced (3.5 Hz) rat right atrial preparations in vitro were recorded. The cumulative concentration (0.01-3.0 microg/ml)-response of venom on spontaneously beating atria exhibited a marked decrease in rate (by 55%) and an increase in force (by 92%) only at a higher concentration (3.0 microg/ml). The venom-induced decrease in rate and increase in force were sensitive to atropine, N-omega-nitro-L-arginine methylester (NO synthase inhibitor) and methylene blue (guanylyl cyclase inhibitor). Further, nifedipine, a Ca(2+) channel antagonist, blocked the force changes but not the rate changes induced by venom. In the paced atrium, on the other hand, a concentration-dependent decrease in force was observed, and at 3 microg/ml, the decrease was 50%. Pretreatment with nifedipine, but not with methylene blue, significantly attenuated the venom-induced force changes in paced atrium. The observations of this study demonstrate that the venom-induced atrial dysrhythmia is mediated through the muscarinic receptor-dependent NO-G-cyclase cell-signaling pathways.
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Affiliation(s)
- Sadhana Kanoo
- Department of Physiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, 221 005, India
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Wang S, Huang L, Wicher D, Chi C, Xu C. Structure-function relationship of bifunctional scorpion toxin BmBKTx1. Acta Biochim Biophys Sin (Shanghai) 2008; 40:955-63. [PMID: 18989577 DOI: 10.1111/j.1745-7270.2008.00479.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
As the first identified scorpion toxin active on both big conductance Ca2+-activated K+ channels (BK) and small conductance Ca2+-activated K+ channels (SK), BmBKTx1 has been proposed to have two separate functional faces for two targets. To investigate this hypothesis, two double mutants, K21A-Y30A and R9A-K11A, together with wild-type toxin were expressed in Escherichia coli. The recombinant toxins were tested on cockroach BK and rat SK2 channel for functional assay. Mutant K21A-Y30A had a dramatic loss of function on BK but retained its function on SK. Mutant R9A-K11A did not lose function on BK or SK. These data support the two functional-face hypothesis and indicate that the BK face is on the C-terminal beta-sheet.
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Affiliation(s)
- Suming Wang
- School of Life Sciences, University of Science and Technology of China, Hefei, China
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Bis-tetrahydroisoquinoline derivatives: AG525E1, a new step in the search for non-quaternary non-peptidic small conductance Ca2+-activated K+ channel blockers. Bioorg Med Chem Lett 2008; 18:3440-5. [DOI: 10.1016/j.bmcl.2008.03.069] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2008] [Revised: 03/21/2008] [Accepted: 03/25/2008] [Indexed: 11/22/2022]
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