1
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Wu LY, Song YJ, Zhang CL, Liu J. K V Channel-Interacting Proteins in the Neurological and Cardiovascular Systems: An Updated Review. Cells 2023; 12:1894. [PMID: 37508558 PMCID: PMC10377897 DOI: 10.3390/cells12141894] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 07/08/2023] [Accepted: 07/10/2023] [Indexed: 07/30/2023] Open
Abstract
KV channel-interacting proteins (KChIP1-4) belong to a family of Ca2+-binding EF-hand proteins that are able to bind to the N-terminus of the KV4 channel α-subunits. KChIPs are predominantly expressed in the brain and heart, where they contribute to the maintenance of the excitability of neurons and cardiomyocytes by modulating the fast inactivating-KV4 currents. As the auxiliary subunit, KChIPs are critically involved in regulating the surface protein expression and gating properties of KV4 channels. Mechanistically, KChIP1, KChIP2, and KChIP3 promote the translocation of KV4 channels to the cell membrane, accelerate voltage-dependent activation, and slow the recovery rate of inactivation, which increases KV4 currents. By contrast, KChIP4 suppresses KV4 trafficking and eliminates the fast inactivation of KV4 currents. In the heart, IKs, ICa,L, and INa can also be regulated by KChIPs. ICa,L and INa are positively regulated by KChIP2, whereas IKs is negatively regulated by KChIP2. Interestingly, KChIP3 is also known as downstream regulatory element antagonist modulator (DREAM) because it can bind directly to the downstream regulatory element (DRE) on the promoters of target genes that are implicated in the regulation of pain, memory, endocrine, immune, and inflammatory reactions. In addition, all the KChIPs can act as transcription factors to repress the expression of genes involved in circadian regulation. Altered expression of KChIPs has been implicated in the pathogenesis of several neurological and cardiovascular diseases. For example, KChIP2 is decreased in failing hearts, while loss of KChIP2 leads to increased susceptibility to arrhythmias. KChIP3 is increased in Alzheimer's disease and amyotrophic lateral sclerosis, but decreased in epilepsy and Huntington's disease. In the present review, we summarize the progress of recent studies regarding the structural properties, physiological functions, and pathological roles of KChIPs in both health and disease. We also summarize the small-molecule compounds that regulate the function of KChIPs. This review will provide an overview and update of the regulatory mechanism of the KChIP family and the progress of targeted drug research as a reference for researchers in related fields.
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Affiliation(s)
- Le-Yi Wu
- Department of Pathophysiology, Shenzhen University Medical School, Shenzhen 518060, China
| | - Yu-Juan Song
- Department of Pathophysiology, Shenzhen University Medical School, Shenzhen 518060, China
| | - Cheng-Lin Zhang
- Department of Pathophysiology, Shenzhen University Medical School, Shenzhen 518060, China
| | - Jie Liu
- Department of Pathophysiology, Shenzhen University Medical School, Shenzhen 518060, China
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2
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Abbott GW. Kv Channel Ancillary Subunits: Where Do We Go from Here? Physiology (Bethesda) 2022; 37:0. [PMID: 35797055 PMCID: PMC9394777 DOI: 10.1152/physiol.00005.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 04/29/2022] [Accepted: 04/29/2022] [Indexed: 01/10/2023] Open
Abstract
Voltage-gated potassium (Kv) channels each comprise four pore-forming α-subunits that orchestrate essential duties such as voltage sensing and K+ selectivity and conductance. In vivo, however, Kv channels also incorporate regulatory subunits-some Kv channel specific, others more general modifiers of protein folding, trafficking, and function. Understanding all the above is essential for a complete picture of the role of Kv channels in physiology and disease.
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Affiliation(s)
- Geoffrey W Abbott
- Bioelectricity Laboratory, Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, California
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3
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Cercós P, Peraza DA, de Benito-Bueno A, Socuéllamos PG, Aziz-Nignan A, Arrechaga-Estévez D, Beato E, Peña-Acevedo E, Albert A, González-Vera JA, Rodríguez Y, Martín-Martínez M, Valenzuela C, Gutiérrez-Rodríguez M. Pharmacological Approaches for the Modulation of the Potassium Channel K V4.x and KChIPs. Int J Mol Sci 2021; 22:ijms22031419. [PMID: 33572566 PMCID: PMC7866805 DOI: 10.3390/ijms22031419] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 01/27/2021] [Accepted: 01/28/2021] [Indexed: 02/06/2023] Open
Abstract
Ion channels are macromolecular complexes present in the plasma membrane and intracellular organelles of cells. Dysfunction of ion channels results in a group of disorders named channelopathies, which represent an extraordinary challenge for study and treatment. In this review, we will focus on voltage-gated potassium channels (KV), specifically on the KV4-family. The activation of these channels generates outward currents operating at subthreshold membrane potentials as recorded from myocardial cells (ITO, transient outward current) and from the somata of hippocampal neurons (ISA). In the heart, KV4 dysfunctions are related to Brugada syndrome, atrial fibrillation, hypertrophy, and heart failure. In hippocampus, KV4.x channelopathies are linked to schizophrenia, epilepsy, and Alzheimer's disease. KV4.x channels need to assemble with other accessory subunits (β) to fully reproduce the ITO and ISA currents. β Subunits affect channel gating and/or the traffic to the plasma membrane, and their dysfunctions may influence channel pharmacology. Among KV4 regulatory subunits, this review aims to analyze the KV4/KChIPs interaction and the effect of small molecule KChIP ligands in the A-type currents generated by the modulation of the KV4/KChIP channel complex. Knowledge gained from structural and functional studies using activators or inhibitors of the potassium current mediated by KV4/KChIPs will better help understand the underlying mechanism involving KV4-mediated-channelopathies, establishing the foundations for drug discovery, and hence their treatments.
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Affiliation(s)
- Pilar Cercós
- Instituto de Química Médica (IQM-CSIC), 28006 Madrid, Spain; (P.C.); (M.M.-M.)
| | - Diego A. Peraza
- Instituto de Investigaciones Biomédicas Alberto Sols (IIBM), CSIC-UAM, 28029 Madrid, Spain; (D.A.P.); (A.d.B.-B.); (P.G.S.)
- Spanish Network for Biomedical Research in Cardiovascular Research (CIBERCV), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Angela de Benito-Bueno
- Instituto de Investigaciones Biomédicas Alberto Sols (IIBM), CSIC-UAM, 28029 Madrid, Spain; (D.A.P.); (A.d.B.-B.); (P.G.S.)
- Spanish Network for Biomedical Research in Cardiovascular Research (CIBERCV), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Paula G. Socuéllamos
- Instituto de Investigaciones Biomédicas Alberto Sols (IIBM), CSIC-UAM, 28029 Madrid, Spain; (D.A.P.); (A.d.B.-B.); (P.G.S.)
- Spanish Network for Biomedical Research in Cardiovascular Research (CIBERCV), Instituto de Salud Carlos III, 28029 Madrid, Spain
| | - Abdoul Aziz-Nignan
- Department of Natural Sciences, Hostos Community College of CUNY, New York, NY 10451, USA; (A.A.-N.); (D.A.-E.); (E.B.); (E.P.-A.); (Y.R.)
| | - Dariel Arrechaga-Estévez
- Department of Natural Sciences, Hostos Community College of CUNY, New York, NY 10451, USA; (A.A.-N.); (D.A.-E.); (E.B.); (E.P.-A.); (Y.R.)
| | - Escarle Beato
- Department of Natural Sciences, Hostos Community College of CUNY, New York, NY 10451, USA; (A.A.-N.); (D.A.-E.); (E.B.); (E.P.-A.); (Y.R.)
| | - Emilio Peña-Acevedo
- Department of Natural Sciences, Hostos Community College of CUNY, New York, NY 10451, USA; (A.A.-N.); (D.A.-E.); (E.B.); (E.P.-A.); (Y.R.)
| | - Armando Albert
- Instituto de Química Física Rocasolano (IQFR-CSIC), 28006 Madrid, Spain;
| | - Juan A. González-Vera
- Departamento de Físicoquímica, Facultad de Farmacia, Universidad de Granada, 18071 Granada, Spain;
| | - Yoel Rodríguez
- Department of Natural Sciences, Hostos Community College of CUNY, New York, NY 10451, USA; (A.A.-N.); (D.A.-E.); (E.B.); (E.P.-A.); (Y.R.)
| | | | - Carmen Valenzuela
- Instituto de Investigaciones Biomédicas Alberto Sols (IIBM), CSIC-UAM, 28029 Madrid, Spain; (D.A.P.); (A.d.B.-B.); (P.G.S.)
- Spanish Network for Biomedical Research in Cardiovascular Research (CIBERCV), Instituto de Salud Carlos III, 28029 Madrid, Spain
- Correspondence: ; (C.V.); (M.G.-R.); Tel.: +34-91-585-4493 (C.V.); +34-91-258-7493 (M.-G.R.)
| | - Marta Gutiérrez-Rodríguez
- Instituto de Química Médica (IQM-CSIC), 28006 Madrid, Spain; (P.C.); (M.M.-M.)
- Correspondence: ; (C.V.); (M.G.-R.); Tel.: +34-91-585-4493 (C.V.); +34-91-258-7493 (M.-G.R.)
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4
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Jenkins CA, Kalmar L, Matiasek K, Mari L, Kyöstilä K, Lohi H, Schofield EC, Mellersh CS, De Risio L, Ricketts SL. Characterisation of canine KCNIP4: A novel gene for cerebellar ataxia identified by whole-genome sequencing two affected Norwegian Buhund dogs. PLoS Genet 2020; 16:e1008527. [PMID: 31999692 PMCID: PMC7012447 DOI: 10.1371/journal.pgen.1008527] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 02/11/2020] [Accepted: 11/15/2019] [Indexed: 12/14/2022] Open
Abstract
A form of hereditary cerebellar ataxia has recently been described in the Norwegian Buhund dog breed. This study aimed to identify the genetic cause of the disease. Whole-genome sequencing of two Norwegian Buhund siblings diagnosed with progressive cerebellar ataxia was carried out, and sequences compared with 405 whole genome sequences of dogs of other breeds to filter benign common variants. Nine variants predicted to be deleterious segregated among the genomes in concordance with an autosomal recessive mode of inheritance, only one of which segregated within the breed when genotyped in additional Norwegian Buhunds. In total this variant was assessed in 802 whole genome sequences, and genotyped in an additional 505 unaffected dogs (including 146 Buhunds), and only four affected Norwegian Buhunds were homozygous for the variant. The variant identified, a T to C single nucleotide polymorphism (SNP) (NC_006585.3:g.88890674T>C), is predicted to cause a tryptophan to arginine substitution in a highly conserved region of the potassium voltage-gated channel interacting protein KCNIP4. This gene has not been implicated previously in hereditary ataxia in any species. Evaluation of KCNIP4 protein expression through western blot and immunohistochemical analysis using cerebellum tissue of affected and control dogs demonstrated that the mutation causes a dramatic reduction of KCNIP4 protein expression. The expression of alternative KCNIP4 transcripts within the canine cerebellum, and regional differences in KCNIP4 protein expression, were characterised through RT-PCR and immunohistochemistry respectively. The voltage-gated potassium channel protein KCND3 has previously been implicated in spinocerebellar ataxia, and our findings suggest that the Kv4 channel complex KCNIP accessory subunits also have an essential role in voltage-gated potassium channel function in the cerebellum and should be investigated as potential candidate genes for cerebellar ataxia in future studies in other species.
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Affiliation(s)
| | - Lajos Kalmar
- Department of Veterinary Medicine, University of Cambridge, Cambridge, Cambridgeshire, United Kingdom
| | - Kaspar Matiasek
- Section of Clinical & Comparative Neuropathology, Centre for Clinical Veterinary Medicine, Ludwig-Maximilians-Universität Munich, München, Germany
| | - Lorenzo Mari
- Neurology/Neurosurgery Service, Centre for Small Animal Studies, Animal Health Trust, Newmarket, Suffolk, United Kingdom
| | - Kaisa Kyöstilä
- Department of Veterinary Biosciences, and Department of Medical and Clinical Genetics, University of Helsinki, Helsinki, Finland
- Folkhälsan Research Center, Helsinki, Finland
| | - Hannes Lohi
- Department of Veterinary Biosciences, and Department of Medical and Clinical Genetics, University of Helsinki, Helsinki, Finland
- Folkhälsan Research Center, Helsinki, Finland
| | - Ellen C. Schofield
- Kennel Club Genetics Centre, Animal Health Trust, Newmarket, Suffolk, United Kingdom
| | - Cathryn S. Mellersh
- Kennel Club Genetics Centre, Animal Health Trust, Newmarket, Suffolk, United Kingdom
| | - Luisa De Risio
- Neurology/Neurosurgery Service, Centre for Small Animal Studies, Animal Health Trust, Newmarket, Suffolk, United Kingdom
| | - Sally L. Ricketts
- Kennel Club Genetics Centre, Animal Health Trust, Newmarket, Suffolk, United Kingdom
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5
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Zhang H, Zhang H, Wang C, Wang Y, Zou R, Shi C, Guan B, Gamper N, Xu Y. Auxiliary subunits control biophysical properties and response to compound NS5806 of the Kv4 potassium channel complex. FASEB J 2019; 34:807-821. [PMID: 31914636 PMCID: PMC6972550 DOI: 10.1096/fj.201902010rr] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 10/28/2019] [Accepted: 11/04/2019] [Indexed: 12/19/2022]
Abstract
Kv4 pore‐forming subunits co‐assemble with β‐subunits including KChIP2 and DPP6 and the resultant complexes conduct cardiac transient outward K+ current (Ito). Compound NS5806 has been shown to potentate Ito in canine cardiomyocytes; however, its effects on Ito in other species yet to be determined. We found that NS5806 inhibited native Ito in a concentration‐dependent manner (0.1~30 μM) in both mouse ventricular cardiomyocytes and human‐induced pluripotent stem cell‐derived cardiomyocytes (hiPSC‐CMs), but potentiated Ito in the canine cardiomyocytes. In HEK293 cells co‐transfected with cloned Kv4.3 (or Kv4.2) and β‐subunit KChIP2, NS5806 significantly increased the peak current amplitude and slowed the inactivation. In contrast, NS5806 suppressed the current and accelerated inactivation of the channels when cells were co‐transfected with Kv4.3 (or Kv4.2), KChIP2 and another β‐subunit, DPP6‐L (long isoform). Western blot analysis showed that DPP6‐L was dominantly expressed in both mouse ventricular myocardium and hiPSC‐CMs, while it was almost undetectable in canine ventricular myocardium. In addition, low level of DPP6‐S expression was found in canine heart, whereas levels of KChIP2 expression were comparable among all three species. siRNA knockdown of DPP6 antagonized the Ito inhibition by NS5806 in hiPSC‐CMs. Molecular docking simulation suggested that DPP6‐L may associate with KChIP2 subunits. Mutations of putative KChIP2‐interacting residues of DPP6‐L reversed the inhibitory effect of NS5806 into potentiation of the current. We conclude that a pharmacological modulator can elicit opposite regulatory effects on Kv4 channel complex among different species, depending on the presence of distinct β‐subunits. These findings provide novel insight into the molecular design and regulation of cardiac Ito. Since Ito is a potential therapeutic target for treatment of multiple cardiovascular diseases, our data will facilitate the development of new therapeutic Ito modulators.
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Affiliation(s)
- Hongxue Zhang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China.,The Key Laboratory of New Drug Pharmacology and Toxicology, Ministry of Education, Shijiazhuang, China.,The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Shijiazhuang, China
| | - Hua Zhang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China.,The Key Laboratory of New Drug Pharmacology and Toxicology, Ministry of Education, Shijiazhuang, China.,The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Shijiazhuang, China
| | - Chanjuan Wang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China.,The Key Laboratory of New Drug Pharmacology and Toxicology, Ministry of Education, Shijiazhuang, China.,The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Shijiazhuang, China
| | - Yuhong Wang
- Institute of Masteria Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
| | - Ruya Zou
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China.,The Key Laboratory of New Drug Pharmacology and Toxicology, Ministry of Education, Shijiazhuang, China.,The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Shijiazhuang, China
| | - Chenxia Shi
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China.,The Key Laboratory of New Drug Pharmacology and Toxicology, Ministry of Education, Shijiazhuang, China.,The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Shijiazhuang, China
| | - Bingcai Guan
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China.,The Key Laboratory of New Drug Pharmacology and Toxicology, Ministry of Education, Shijiazhuang, China.,The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Shijiazhuang, China
| | - Nikita Gamper
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China.,School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Yanfang Xu
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, China.,The Key Laboratory of New Drug Pharmacology and Toxicology, Ministry of Education, Shijiazhuang, China.,The Key Laboratory of Neural and Vascular Biology, Ministry of Education, Shijiazhuang, China
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6
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Abstract
Kv channel-interacting proteins (KChIPs) belong to the neuronal calcium sensor (NCS) family of Ca2+-binding EF-hand proteins. KChIPs constitute a group of specific auxiliary β-subunits for Kv4 channels, the molecular substrate of transient potassium currents in both neuronal and non-neuronal tissues. Moreover, KChIPs can interact with presenilins to control ER calcium signaling and apoptosis, and with DNA to control gene transcription. Ca2+ binding via their EF-hands, with the consequence of conformational changes, is well documented for KChIPs. Moreover, the Ca2+ dependence of the presenilin/KChIP complex may be related to Alzheimer’s disease and the Ca2+ dependence of the DNA/KChIP complex to pain sensing. However, only in few cases could the Ca2+ binding to KChIPs be directly linked to the control of excitability in nerve and muscle cells known to express Kv4/KChIP channel complexes. This review summarizes current knowledge about the Ca2+ binding properties of KChIPs and the Ca2+ dependencies of macromolecular complexes containing KChIPs, including those with presenilins, DNA and especially Kv4 channels. The respective physiological or pathophysiolgical roles of Ca2+ binding to KChIPs are discussed.
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Affiliation(s)
- Robert Bähring
- a Institut für Zelluläre und Integrative Physiologie, Zentrum für Experimentelle Medizin , Universitätsklinikum Hamburg-Eppendorf , Hamburg , Germany
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7
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Sun LL, Yang TY, Wei NN, Lu W, Jiao WX, Zhou QQ, Miao YZ, Gao Q, Wang XT, Sun Q, Wang K. Pharmacological characterization of JWX-A0108 as a novel type I positive allosteric modulator of α7 nAChR that can reverse acoustic gating deficits in a mouse prepulse inhibition model. Acta Pharmacol Sin 2019; 40:737-745. [PMID: 30333556 PMCID: PMC6786413 DOI: 10.1038/s41401-018-0163-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 08/27/2018] [Indexed: 12/26/2022] Open
Abstract
The α7 nicotinic acetylcholine receptor (α7 nAChR) is a ligand-gated Ca2+-permeable homopentameric ion channel implicated in cognition and neuropsychiatric disorders. Pharmacological enhancement of α7 nAChR function has been suggested for improvement of cognitive deficits. In the present study, we characterized a thiazolyl heterocyclic derivative, 6-(2-chloro-6-methylphenyl)-2-((3-fluoro-4-methylphenyl)amino)thiazolo[4,5-d]pyrimidin-7(6H)-one (JWX-A0108), as a novel type I α7 nAChR positive allosteric modulator (PAM), and evaluated its ability to reverse auditory gating and spatial working memory deficits in mice. In Xenopus oocytes expressing human nAChR channels, application of JWX-A0108 selectively enhanced α7 nAChR-mediated inward current in the presence of the agonist ACh (EC50 value = 4.35 ± 0.12 µM). In hippocampal slices, co-application of ACh and JWX-A0108 (10 µM for each) markedly increased both the frequency and amplitude of spontaneous inhibitory postsynaptic currents (sIPSCs) recorded in pyramidal neurons, but JWX-A0108 did not affect GABA-induced current in oocytes expressing human GABAA receptor α1β3γ2 and α5β3γ2 subtypes. In mice with MK-801-induced deficits in auditory gating, administration of JWX-A0108 (1, 3, and 10 mg/kg, i.p.) dose-dependently attenuates MK-801-induced auditory gating deficits in five prepulse intensities (72, 76, 80, 84, and 88 dB). Furthermore, administration of JWX-A0108 (0.03, 0.1, or 0.3 mg/kg, i.p.) significantly reversed MK-801-induced impaired spatial working memory in mice. Our results demonstrate that JWX-A0108 is a novel type I PAM of α7 nAChR, which may be beneficial for improvement of cognitive deficits commonly found in neuropsychiatric disorders such as schizophrenia and Alzheimer's disease.
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Affiliation(s)
- Li-Lan Sun
- Department of Pharmacology, Qingdao University School of Pharmacy, Qingdao, 266021, China
| | - Tao-Yi Yang
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing, 100191, China
| | - Ning-Ning Wei
- Department of Pharmacology, Qingdao University School of Pharmacy, Qingdao, 266021, China
| | - Wei Lu
- Department of Pharmacology, Qingdao University School of Pharmacy, Qingdao, 266021, China
| | - Wen-Xuan Jiao
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing, 100191, China
| | - Qi-Qi Zhou
- Department of Pharmacology, Qingdao University School of Pharmacy, Qingdao, 266021, China
| | - Yong-Zhen Miao
- Department of Pharmacology, Qingdao University School of Pharmacy, Qingdao, 266021, China
| | - Qin Gao
- Department of Pharmacology, Qingdao University School of Pharmacy, Qingdao, 266021, China
| | - Xin-Tong Wang
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing, 100191, China
| | - Qi Sun
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing, 100191, China.
| | - KeWei Wang
- Department of Pharmacology, Qingdao University School of Pharmacy, Qingdao, 266021, China.
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8
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Murphy JG, Hoffman DA. A polybasic motif in alternatively spliced KChIP2 isoforms prevents Ca 2+ regulation of Kv4 channels. J Biol Chem 2019; 294:3683-3695. [PMID: 30622142 DOI: 10.1074/jbc.ra118.006549] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 01/04/2019] [Indexed: 11/06/2022] Open
Abstract
The Kv4 family of A-type voltage-gated K+ channels regulates the excitability in hippocampal pyramidal neuron dendrites and are key determinants of dendritic integration, spike timing-dependent plasticity, long-term potentiation, and learning. Kv4.2 channel expression is down-regulated following hippocampal seizures and in epilepsy, suggesting A-type currents as therapeutic targets. In addition to pore-forming Kv4 subunits, modulatory auxiliary subunits called K+ channel-interacting proteins (KChIPs) modulate Kv4 expression and activity and are required to recapitulate native hippocampal A-type currents in heterologous expression systems. KChIP mRNAs contain multiple start sites and alternative exons that generate considerable N-terminal variation and functional diversity in shaping Kv4 currents. As members of the EF-hand domain-containing neuronal Ca2+ sensor protein family, KChIP auxiliary proteins may convey Ca2+ sensitivity upon Kv4 channels; however, to what degree intracellular Ca2+ regulates KChIP-Kv4.2 complexes is unclear. To answer this question, we expressed KChIP2 with Kv4.2 in HEK293T cells, and, with whole-cell patch-clamp electrophysiology, measured an ∼1.5-fold increase in Kv4.2 current density in the presence of elevated intracellular Ca2+ Intriguingly, the Ca2+ regulation of Kv4 current was specific to KChIP2b and KChIP2c splice isoforms that lack a putative polybasic domain that is present in longer KChIP2a1 and KChIP2a isoforms. Site-directed acidification of the basic residues within the polybasic motif of KChIP2a1 rescued Ca2+-mediated regulation of Kv4 current density. These results support divergent Ca2+ regulation of Kv4 channels mediated by alternative splicing of KChIP2 isoforms. They suggest that distinct KChIP-Kv4 interactions may differentially control excitability and function of hippocampal dendrites.
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Affiliation(s)
- Jonathan G Murphy
- From the NIGMS and .,Section on Molecular Neurophysiology, NICHD, National Institutes of Health, Bethesda, Maryland 20892
| | - Dax A Hoffman
- Section on Molecular Neurophysiology, NICHD, National Institutes of Health, Bethesda, Maryland 20892
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9
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Inhibition of Hsp70 Suppresses Neuronal Hyperexcitability and Attenuates Epilepsy by Enhancing A-Type Potassium Current. Cell Rep 2019; 26:168-181.e4. [DOI: 10.1016/j.celrep.2018.12.032] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 10/06/2018] [Accepted: 12/06/2018] [Indexed: 01/03/2023] Open
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10
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Li L, Wang P, Hu K, Wang X, Cai W, Ai C, Liu S, Wang Z. PFMG1 promotes osteoblast differentiation and prevents osteoporotic bone loss. FASEB J 2018; 32:838-849. [PMID: 29021211 DOI: 10.1096/fj.201700422r] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Nacre is a widely used mineral medicine that has been reported to have beneficial effects in bone remodeling without an increase in inflammation. Water-soluble nacre matrix has been demonstrated to be responsible for the effect, yet core active ingredients are unknown. Pinctada fucata mantle gene 1 (PFMG1) was first discovered in the mantle tissue of Pinctada fucata. The protein has 2 EF-hands, a calcium-binding domain. PFMG1 protein can affect the growth of calcium carbonate crystals in vitro. Here, we demonstrate that PFMG1 affects cell-cycle distribution and promotes preosteoblast proliferation. PFMG1 accelerates preosteoblast differentiation and extracellular matrix mineralization. During the differentiation process, PFMG1 increases the expression level of osteoblastic marker genes and activates the Erk signaling pathway. PFMG1 also accelerates calcium crystal aggregation in culture medium and suppresses osteoclast formation. Moreover, PFMG1 prevents bone loss caused by ovariectomy. RNA sequencing analysis demonstrated that PFMG1 stimulates genes that are associated with tissue development and ossification, which indicated new genes that function in bone remodeling. Our findings demonstrate the therapeutic potential of PFMG1 from nacre as a novel medicine for osteoporosis.-Li, L., Wang, P., Hu, K., Wang, X., Cai, W., Ai, C., Liu, S., Wang, Z. PFMG1 promotes osteoblast differentiation and prevents osteoporotic bone loss.
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Affiliation(s)
- Liyuan Li
- Protein Science Key Laboratory, Ministry of Education, School of Pharmaceutical Sciences, Tsinghua University, Beijing, China
| | - Pan Wang
- Protein Science Key Laboratory, Ministry of Education, School of Pharmaceutical Sciences, Tsinghua University, Beijing, China
| | - Kaiqiang Hu
- Protein Science Key Laboratory, Ministry of Education, School of Pharmaceutical Sciences, Tsinghua University, Beijing, China
| | - Xiaoyan Wang
- Protein Science Key Laboratory, Ministry of Education, School of Pharmaceutical Sciences, Tsinghua University, Beijing, China.,Department of Chemistry and Biology, College of Science, National University of Defense Technology, Changsha, China
| | - Wenping Cai
- Department of Stomatology, Huashan Hospital, Fudan University, Shanghai, China
| | - Chao Ai
- Protein Science Key Laboratory, Ministry of Education, School of Pharmaceutical Sciences, Tsinghua University, Beijing, China.,Department of Pharmacy, Beijing Tsinghua Changgung Hospital, Tsinghua University Medical Center, Beijing, China
| | - Shangfeng Liu
- Department of Stomatology, Huashan Hospital, Fudan University, Shanghai, China
| | - Zhao Wang
- Protein Science Key Laboratory, Ministry of Education, School of Pharmaceutical Sciences, Tsinghua University, Beijing, China
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11
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Zhang H, Reichert E, Cohen AE. Optical electrophysiology for probing function and pharmacology of voltage-gated ion channels. eLife 2016; 5. [PMID: 27215841 PMCID: PMC4907688 DOI: 10.7554/elife.15202] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2016] [Accepted: 05/12/2016] [Indexed: 12/15/2022] Open
Abstract
Voltage-gated ion channels mediate electrical dynamics in excitable tissues and are an important class of drug targets. Channels can gate in sub-millisecond timescales, show complex manifolds of conformational states, and often show state-dependent pharmacology. Mechanistic studies of ion channels typically involve sophisticated voltage-clamp protocols applied through manual or automated electrophysiology. Here, we develop all-optical electrophysiology techniques to study activity-dependent modulation of ion channels, in a format compatible with high-throughput screening. Using optical electrophysiology, we recapitulate many voltage-clamp protocols and apply to Nav1.7, a channel implicated in pain. Optical measurements reveal that a sustained depolarization strongly potentiates the inhibitory effect of PF-04856264, a Nav1.7-specific blocker. In a pilot screen, we stratify a library of 320 FDA-approved compounds by binding mechanism and kinetics, and find close concordance with patch clamp measurements. Optical electrophysiology provides a favorable tradeoff between throughput and information content for studies of NaV channels, and possibly other voltage-gated channels. DOI:http://dx.doi.org/10.7554/eLife.15202.001 Ion channels are specialized proteins that span the cell membrane. When activated, these channels allow ions to pass through them, which can produce electrical spikes that carry information in nerve cells and regulate the beating of the heart. Researchers interested in understanding how ion channels behave often use a technique called patch clamp electrophysiology to measure the electrical current across the cell membrane. The technique can be used to probe if a specific drug can block an ion channel, but it is not well suited to screening lots of potential drugs because it is slow and expensive. A group of ion channels known as voltage-gated sodium channels play an important role in generating the electrical spikes in nerve cells. One subtype called NaV1.7 is involved in sensing pain and drugs that block NaV1.7 might be useable as painkillers, but only if they are specific to this channel. This is because there are many similar sodium channels that are important in other processes in the body. Zhang et al. have now developed a new light-based technique to measure how ion channels behave. The technique uses light to activate the channel and a fluorescent protein to report on the membrane’s voltage. Zhang et al. used the new technique to probe how sodium channels, in particular NaV1.7, interact with drugs. Mammalian cells grown in the lab were engineered to produce NaV1.7, a light-activated ion channel (called CheRiff), and a fluorescent reporter protein. A flash of blue light delivered to the cells activated CheRiff, which in turn activated NaV1.7. At the same time, the fluorescence of the reporter protein was used as a read-out of NaV1.7’s activity. Zhang et al. showed that they could reproduce many conventional electrophysiology measurements using their new light-based approach. Optical measurements were then used to screen 320 drugs to see whether they could block NaV1.7. The results of the screen corresponded closely with measurements made using conventional electrophysiology. These results demonstrate that the new optical technique is both fast and precise enough to be used in drug discovery. Further studies could now ask if this optical technique can also be used to study other ion channels, such as potassium channels and calcium channels. DOI:http://dx.doi.org/10.7554/eLife.15202.002
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Affiliation(s)
- Hongkang Zhang
- Departments of Chemistry and Chemical Biology and Physics, Harvard University, Cambridge, United States.,Howard Hughes Medical Institute, Harvard University, Cambridge, United States
| | - Elaine Reichert
- Departments of Chemistry and Chemical Biology and Physics, Harvard University, Cambridge, United States
| | - Adam E Cohen
- Departments of Chemistry and Chemical Biology and Physics, Harvard University, Cambridge, United States.,Howard Hughes Medical Institute, Harvard University, Cambridge, United States
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12
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Zhou J, Tang Y, Zheng Q, Li M, Yuan T, Chen L, Huang Z, Wang K. Different KChIPs compete for heteromultimeric assembly with pore-forming Kv4 subunits. Biophys J 2016; 108:2658-69. [PMID: 26039167 DOI: 10.1016/j.bpj.2015.04.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Revised: 03/24/2015] [Accepted: 04/20/2015] [Indexed: 01/23/2023] Open
Abstract
Auxiliary Kv channel-interacting proteins 1-4 (KChIPs1-4) coassemble with pore-forming Kv4 α-subunits to form channel complexes underlying somatodendritic subthreshold A-type current that regulates neuronal excitability. It has been hypothesized that different KChIPs can competitively bind to Kv4 α-subunit to form variable channel complexes that can exhibit distinct biophysical properties for modulation of neural function. In this study, we use single-molecule subunit counting by total internal reflection fluorescence microscopy in combinations with electrophysiology and biochemistry to investigate whether different isoforms of auxiliary KChIPs, KChIP4a, and KChIP4bl, can compete for binding of Kv4.3 to coassemble heteromultimeric channel complexes for modulation of channel function. To count the number of photobleaching steps solely from cell membrane, we take advantage of a membrane tethered k-ras-CAAX peptide that anchors cytosolic KChIP4 proteins to the surface for reduction of background noise. Single-molecule subunit counting reveals that the number of KChIP4 isoforms in Kv4.3-KChIP4 complexes can vary depending on the KChIP4 expression level. Increasing the amount of KChIP4bl gradually reduces bleaching steps of KChIP4a isoform proteins, and vice versa. Further analysis of channel gating kinetics from different Kv4-KChIP4 subunit compositions confirms that both KChIP4a and KChIP4bl can modulate the channel complex function upon coassembly. Taken together, our findings show that auxiliary KChIPs can heteroassemble with Kv4 in a competitive manner to form heteromultimeric Kv4-KChIP4 channel complexes that are biophysically distinct and regulated under physiological or pathological conditions.
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Affiliation(s)
- Jingheng Zhou
- Department of Neurobiology, Neuroscience Research Institute, Peking University Health Science Center, Beijing, China
| | - Yiquan Tang
- Department of Molecular and Cellular Pharmacology, PKU-IDG/McGovern Institute for Brain Research, Peking University School of Pharmaceutical Sciences, Beijing, China; Qingdao University School of Pharmacy, Qingdao, China
| | - Qin Zheng
- Department of Neurobiology, Neuroscience Research Institute, Peking University Health Science Center, Beijing, China
| | - Meng Li
- Department of Neurobiology, Neuroscience Research Institute, Peking University Health Science Center, Beijing, China
| | - Tianyi Yuan
- Institute of Molecular Medicine, Peking University, Beijing, China
| | - Liangyi Chen
- Institute of Molecular Medicine, Peking University, Beijing, China
| | - Zhuo Huang
- Department of Molecular and Cellular Pharmacology, PKU-IDG/McGovern Institute for Brain Research, Peking University School of Pharmaceutical Sciences, Beijing, China
| | - KeWei Wang
- Department of Neurobiology, Neuroscience Research Institute, Peking University Health Science Center, Beijing, China; Department of Molecular and Cellular Pharmacology, PKU-IDG/McGovern Institute for Brain Research, Peking University School of Pharmaceutical Sciences, Beijing, China; Qingdao University School of Pharmacy, Qingdao, China.
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13
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The tetramerization domain potentiates Kv4 channel function by suppressing closed-state inactivation. Biophys J 2015; 107:1090-1104. [PMID: 25185545 DOI: 10.1016/j.bpj.2014.07.038] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 05/25/2014] [Accepted: 07/01/2014] [Indexed: 01/26/2023] Open
Abstract
A-type Kv4 potassium channels undergo a conformational change toward a nonconductive state at negative membrane potentials, a dynamic process known as pre-open closed states or closed-state inactivation (CSI). CSI causes inhibition of channel activity without the prerequisite of channel opening, thus providing a dynamic regulation of neuronal excitability, dendritic signal integration, and synaptic plasticity at resting. However, the structural determinants underlying Kv4 CSI remain largely unknown. We recently showed that the auxiliary KChIP4a subunit contains an N-terminal Kv4 inhibitory domain (KID) that directly interacts with Kv4.3 channels to enhance CSI. In this study, we utilized the KChIP4a KID to probe key structural elements underlying Kv4 CSI. Using fluorescence resonance energy transfer two-hybrid mapping and bimolecular fluorescence complementation-based screening combined with electrophysiology, we identified the intracellular tetramerization (T1) domain that functions to suppress CSI and serves as a receptor for the binding of KID. Disrupting the Kv4.3 T1-T1 interaction interface by mutating C110A within the C3H1 motif of T1 domain facilitated CSI and ablated the KID-mediated enhancement of CSI. Furthermore, replacing the Kv4.3 T1 domain with the T1 domain from Kv1.4 (without the C3H1 motif) or Kv2.1 (with the C3H1 motif) resulted in channels functioning with enhanced or suppressed CSI, respectively. Taken together, our findings reveal a novel (to our knowledge) role of the T1 domain in suppressing Kv4 CSI, and that KChIP4a KID directly interacts with the T1 domain to facilitate Kv4.3 CSI, thus leading to inhibition of channel function.
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14
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Gonzalez WG, Arango AS, Miksovska J. Amphiphilic Residues 29–44 of DREAM N-Termini Mediate Calmodulin:DREAM Complex Formation. Biochemistry 2015; 54:4391-403. [DOI: 10.1021/acs.biochem.5b00251] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Walter G. Gonzalez
- Department
of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
| | - Andres S. Arango
- Department
of Physics, Florida International University, Miami, Florida 33199, United States
| | - Jaroslava Miksovska
- Department
of Chemistry and Biochemistry, Florida International University, Miami, Florida 33199, United States
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15
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Hao Y, Tang J, Wang K. Development of Automated Patch Clamp Assay for Evaluation of α7 Nicotinic Acetylcholine Receptor Agonists in Automated QPatch-16. Assay Drug Dev Technol 2015; 13:174-84. [PMID: 25880723 DOI: 10.1089/adt.2014.622] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The α7 nicotinic acetylcholine receptor (α7 nAChR) is an important and challenging target for drug discovery in the area of neuropsychiatric disorders. The current screening for chemicals targeting α7 nAChRs is primarily achieved by the use of low-throughput assay two-electrode voltage clamp (TEVC) in nonmammalian Xenopus oocytes. Automated patch clamp system has emerged as an attractive approach compared to conventional electrophysiology. To develop a mammalian cell-based functional assay in an automated electrophysiology system, we in this study generated a stable expression of α7 nAChRs in GH3 cells that originated from a rat pituitary tumor cell line and utilized automated QPatch-16 to test a set of tool compounds and chemicals identified as α7 agonists by TEVC. For the improvement of evaluating weak or partial α7 nAChRs agonists, we achieved enhancement of the signal-to-noise ratio by the addition of a positive allosteric modulator PNU-120596, which only activates α7 current in the presence of agonist. This improved assay was further validated by using known α7 partial agonists, such as RG3487, EVP-6124, and A-P90. Using this validated assay, we were able to identify a novel agonist 140507C that partially activates α7 nAChRs. Taken together, our results validate the use of QPatch-16 for evaluation α7 partial agonists, demonstrating its utility as an effective tool for α7 ion channel drug discovery.
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Affiliation(s)
- Yuchen Hao
- 1 Department of Molecular and Cellular Pharmacology, State Key Laboratory of Natural and Biomimetic Drugs, Peking University School of Pharmaceutical Sciences , Beijing, China
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16
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Kitazawa M, Kubo Y, Nakajo K. The stoichiometry and biophysical properties of the Kv4 potassium channel complex with K+ channel-interacting protein (KChIP) subunits are variable, depending on the relative expression level. J Biol Chem 2014; 289:17597-609. [PMID: 24811166 DOI: 10.1074/jbc.m114.563452] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Kv4 is a voltage-gated K(+) channel, which underlies somatodendritic subthreshold A-type current (ISA) and cardiac transient outward K(+) (Ito) current. Various ion channel properties of Kv4 are known to be modulated by its auxiliary subunits, such as K(+) channel-interacting protein (KChIP) or dipeptidyl peptidase-like protein. KChIP is a cytoplasmic protein and increases the current amplitude, decelerates the inactivation, and accelerates the recovery from inactivation of Kv4. Crystal structure analysis demonstrated that Kv4 and KChIP form an octameric complex with four Kv4 subunits and four KChIP subunits. However, it remains unknown whether the Kv4·KChIP complex can have a different stoichiometry other than 4:4. In this study, we expressed Kv4.2 and KChIP4 with various ratios in Xenopus oocytes and observed that the biophysical properties of Kv4.2 gradually changed with the increase in co-expressed KChIP4. The tandem repeat constructs of Kv4.2 and KChIP4 revealed that the 4:4 (Kv4.2/KChIP4) channel shows faster recovery than the 4:2 channel, suggesting that the biophysical properties of Kv4.2 change, depending on the number of bound KChIP4s. Subunit counting by single-molecule imaging revealed that the bound number of KChIP4 in each Kv4.2·KChIP4 complex was dependent on the expression level of KChIP4. Taken together, we conclude that the stoichiometry of Kv4·KChIP complex is variable, and the biophysical properties of Kv4 change depending on the number of bound KChIP subunits.
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Affiliation(s)
- Masahiro Kitazawa
- From the Division of Biophysics and Neurobiology, Department of Molecular Physiology, National Institute for Physiological Sciences, Okazaki, Aichi 444-8585, Japan and the Department of Physiological Sciences, Graduate University for Advanced Studies (SOKENDAI), Hayama, Kanagawa 240-0155, Japan
| | - Yoshihiro Kubo
- From the Division of Biophysics and Neurobiology, Department of Molecular Physiology, National Institute for Physiological Sciences, Okazaki, Aichi 444-8585, Japan and the Department of Physiological Sciences, Graduate University for Advanced Studies (SOKENDAI), Hayama, Kanagawa 240-0155, Japan
| | - Koichi Nakajo
- From the Division of Biophysics and Neurobiology, Department of Molecular Physiology, National Institute for Physiological Sciences, Okazaki, Aichi 444-8585, Japan and the Department of Physiological Sciences, Graduate University for Advanced Studies (SOKENDAI), Hayama, Kanagawa 240-0155, Japan
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17
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Jerng HH, Pfaffinger PJ. Modulatory mechanisms and multiple functions of somatodendritic A-type K (+) channel auxiliary subunits. Front Cell Neurosci 2014; 8:82. [PMID: 24723849 PMCID: PMC3973911 DOI: 10.3389/fncel.2014.00082] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 03/03/2014] [Indexed: 12/13/2022] Open
Abstract
Auxiliary subunits are non-conducting, modulatory components of the multi-protein ion channel complexes that underlie normal neuronal signaling. They interact with the pore-forming α-subunits to modulate surface distribution, ion conductance, and channel gating properties. For the somatodendritic subthreshold A-type potassium (ISA) channel based on Kv4 α-subunits, two types of auxiliary subunits have been extensively studied: Kv channel-interacting proteins (KChIPs) and dipeptidyl peptidase-like proteins (DPLPs). KChIPs are cytoplasmic calcium-binding proteins that interact with intracellular portions of the Kv4 subunits, whereas DPLPs are type II transmembrane proteins that associate with the Kv4 channel core. Both KChIPs and DPLPs genes contain multiple start sites that are used by various neuronal populations to drive the differential expression of functionally distinct N-terminal variants. In turn, these N-terminal variants generate tremendous functional diversity across the nervous system. Here, we focus our review on (1) the molecular mechanism underlying the unique properties of different N-terminal variants, (2) the shaping of native ISA properties by the concerted actions of KChIPs and DPLP variants, and (3) the surprising ways that KChIPs and DPLPs coordinate the activity of multiple channels to fine-tune neuronal excitability. Unlocking the unique contributions of different auxiliary subunit N-terminal variants may provide an important opportunity to develop novel targeted therapeutics to treat numerous neurological disorders.
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Affiliation(s)
- Henry H. Jerng
- Department of Neuroscience, Baylor College of MedicineHouston, TX, USA
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18
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Interactions of KChIP4a and its mutants with Ca2+ or Kv4.3 N-terminus by affinity capillary electrophoresis. Anal Biochem 2014; 449:99-105. [DOI: 10.1016/j.ab.2013.12.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2013] [Revised: 12/05/2013] [Accepted: 12/12/2013] [Indexed: 11/21/2022]
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19
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Martin VM, Johnson JR, Haynes LP, Barclay JW, Burgoyne RD. Identification of key structural elements for neuronal calcium sensor-1 function in the regulation of the temperature-dependency of locomotion in C. elegans. Mol Brain 2013; 6:39. [PMID: 23981466 PMCID: PMC3765893 DOI: 10.1186/1756-6606-6-39] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Accepted: 08/24/2013] [Indexed: 11/10/2022] Open
Abstract
Background Intracellular Ca2+ regulates many aspects of neuronal function through Ca2+ binding to EF hand-containing Ca2+ sensors that in turn bind target proteins to regulate their function. Amongst the sensors are the neuronal calcium sensor (NCS) family of proteins that are involved in multiple neuronal signalling pathways. Each NCS protein has specific and overlapping targets and physiological functions and specificity is likely to be determined by structural features within the proteins. Common to the NCS proteins is the exposure of a hydrophobic groove, allowing target binding in the Ca2+-loaded form. Structural analysis of NCS protein complexes with target peptides has indicated common and distinct aspects of target protein interaction. Two key differences between NCS proteins are the size of the hydrophobic groove that is exposed for interaction and the role of their non-conserved C-terminal tails. Results We characterised the role of NCS-1 in a temperature-dependent locomotion assay in C. elegans and identified a distinct phenotype in the ncs-1 null in which the worms do not show reduced locomotion at actually elevated temperature. Using rescue of this phenotype we showed that NCS-1 functions in AIY neurons. Structure/function analysis introducing single or double mutations within the hydrophobic groove based on information from characterised target complexes established that both N- and C-terminal pockets of the groove are functionally important and that deletion of the C-terminal tail of NCS-1 did not impair its ability to rescue. Conclusions The current work has allowed physiological assessment of suggestions from structural studies on the key structural features that underlie the interaction of NCS-1 with its target proteins. The results are consistent with the notion that full length of the hydrophobic groove is required for the regulatory interactions underlying NCS-1 function whereas the C-terminal tail of NCS-1 is not essential. This has allowed discrimination between two potential modes of interaction of NCS-1 with its targets.
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Affiliation(s)
- Victoria M Martin
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, University of Liverpool, Liverpool, L69 3BX, UK.
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20
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Tang YQ, Liang P, Zhou J, Lu Y, Lei L, Bian X, Wang K. Auxiliary KChIP4a suppresses A-type K+ current through endoplasmic reticulum (ER) retention and promoting closed-state inactivation of Kv4 channels. J Biol Chem 2013; 288:14727-41. [PMID: 23576435 DOI: 10.1074/jbc.m113.466052] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
In the brain and heart, auxiliary Kv channel-interacting proteins (KChIPs) co-assemble with pore-forming Kv4 α-subunits to form a native K(+) channel complex and regulate the expression and gating properties of Kv4 currents. Among the KChIP1-4 members, KChIP4a exhibits a unique N terminus that is known to suppress Kv4 function, but the underlying mechanism of Kv4 inhibition remains unknown. Using a combination of confocal imaging, surface biotinylation, and electrophysiological recordings, we identified a novel endoplasmic reticulum (ER) retention motif, consisting of six hydrophobic and aliphatic residues, 12-17 (LIVIVL), within the KChIP4a N-terminal KID, that functions to reduce surface expression of Kv4-KChIP complexes. This ER retention capacity is transferable and depends on its flanking location. In addition, adjacent to the ER retention motif, the residues 19-21 (VKL motif) directly promote closed-state inactivation of Kv4.3, thus leading to an inhibition of channel current. Taken together, our findings demonstrate that KChIP4a suppresses A-type Kv4 current via ER retention and enhancement of Kv4 closed-state inactivation.
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Affiliation(s)
- Yi-Quan Tang
- Department of Neurobiology, Neuroscience Research Institute, Peking University Health Science Center, Peking University School of Pharmaceutical Sciences, Beijing 100191, China
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21
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Wang K, Wang Y. Negative modulation of NMDA receptor channel function by DREAM/calsenilin/KChIP3 provides neuroprotection? Front Mol Neurosci 2012; 5:39. [PMID: 22518099 PMCID: PMC3325484 DOI: 10.3389/fnmol.2012.00039] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Accepted: 03/15/2012] [Indexed: 01/08/2023] Open
Abstract
N-methyl-D-aspartate receptors (NMDARs) are glutamate-gated ion channels highly permeable to calcium and essential to excitatory neurotransmission. The NMDARs have attracted much attention because of their role in synaptic plasticity and excitotoxicity. Evidence has recently accumulated that NMDARs are negatively regulated by intracellular calcium binding proteins. The calcium-dependent suppression of NMDAR function serves as a feedback mechanism capable of regulating subsequent Ca2+ entry into the postsynaptic cell, and may offer an alternative approach to treating NMDAR-mediated excitotoxic injury. This short review summarizes the recent progress made in understanding the negative modulation of NMDAR function by DREAM/calsenilin/KChIP3, a neuronal calcium sensor (NCS) protein.
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Affiliation(s)
- Kewei Wang
- Department of Molecular and Cellular Pharmacology, State Key Laboratory of Natural and Biomimetic Drugs, Peking University School of Pharmaceutical Sciences Beijing, China
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22
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Burgoyne RD, Haynes LP. Understanding the physiological roles of the neuronal calcium sensor proteins. Mol Brain 2012; 5:2. [PMID: 22269068 PMCID: PMC3271974 DOI: 10.1186/1756-6606-5-2] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Accepted: 01/23/2012] [Indexed: 01/22/2023] Open
Abstract
Calcium signalling plays a crucial role in the control of neuronal function and plasticity. Changes in neuronal Ca2+ concentration are detected by Ca2+-binding proteins that can interact with and regulate target proteins to modify their function. Members of the neuronal calcium sensor (NCS) protein family have multiple non-redundant roles in the nervous system. Here we review recent advances in the understanding of the physiological roles of the NCS proteins and the molecular basis for their specificity.
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Affiliation(s)
- Robert D Burgoyne
- Department of Cellular and Molecular Physiology, The Physiological Laboratory, Institute of Translational Medicine, University of Liverpool, Liverpool, UK.
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23
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Identification of the critical structural determinants of the EF-hand domain arrangements in calcium binding proteins. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2012; 1824:608-19. [PMID: 22285364 DOI: 10.1016/j.bbapap.2012.01.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Revised: 12/02/2011] [Accepted: 01/04/2012] [Indexed: 11/22/2022]
Abstract
EF-hand calcium binding proteins (CaBPs) share strong sequence homology, but exhibit great diversity in structure and function. Thus although calmodulin (CaM) and calcineurin B (CNB) both consist of four EF hands, their domain arrangements are quite distinct. CaM and the CaM-like proteins are characterized by an extended architecture, whereas CNB and the CNB-like proteins have a more compact form. In this study, we performed structural alignments and molecular dynamics (MD) simulations on 3 CaM-like proteins and 6 CNB-like proteins, and quantified their distinct structural and dynamical features in an effort to establish how their sequences specify their structures and dynamics. Alignments of the EF2-EF3 region of these proteins revealed that several residues (not restricted to the linker between the EF2 and EF3 motifs) differed between the two groups of proteins. A customized inverse folding approach followed by structural assessments and MD simulations established the critical role of these residues in determining the structure of the proteins. Identification of the critical determinants of the two different EF-hand domain arrangements and the distinct dynamical features relevant to their respective functions provides insight into the relationships between sequence, structure, dynamics and function among these EF-hand CaBPs.
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24
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Kunze M, Neuberger G, Maurer-Stroh S, Ma J, Eck T, Braverman N, Schmid JA, Eisenhaber F, Berger J. Structural requirements for interaction of peroxisomal targeting signal 2 and its receptor PEX7. J Biol Chem 2011; 286:45048-62. [PMID: 22057399 DOI: 10.1074/jbc.m111.301853] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The import of a subset of peroxisomal matrix proteins is mediated by the peroxisomal targeting signal 2 (PTS2). The results of our sequence and physical property analysis of known PTS2 signals and of a mutational study of the least characterized amino acids of a canonical PTS2 motif indicate that PTS2 forms an amphipathic helix accumulating all conserved residues on one side. Three-dimensional structural modeling of the PTS2 receptor PEX7 reveals a groove with an evolutionarily conserved charge distribution complementary to PTS2 signals. Mammalian two-hybrid assays and cross-complementation of a mutation in PTS2 by a compensatory mutation in PEX7 confirm the interaction site. An unstructured linker region separates the PTS2 signal from the core protein. This additional information on PTS2 signals was used to generate a PTS2 prediction algorithm that enabled us to identify novel PTS2 signals within human proteins and to describe KChIP4 as a novel peroxisomal protein.
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Affiliation(s)
- Markus Kunze
- Center for Brain Research, Medical University of Vienna, Spitalgasse 4, 1090 Vienna, Austria
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25
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Liang P, Chen H, Cui Y, Lei L, Wang K. Functional rescue of Kv4.3 channel tetramerization mutants by KChIP4a. Biophys J 2010; 98:2867-76. [PMID: 20550899 DOI: 10.1016/j.bpj.2010.03.044] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Revised: 03/12/2010] [Accepted: 03/15/2010] [Indexed: 11/16/2022] Open
Abstract
KChIP4a shows a high homology with other members of the family of Kv channel-interacting proteins (KChIPs) in the conserved C-terminal core region, but exhibits a unique modulation of Kv4 channel gating and surface expression. Unlike KChIP1, the KChIP4 splice variant KChIP4a has been shown to inhibit surface expression and function as a suppressor of channel inactivation of Kv4. In this study, we sought to determine whether the multitasking KChIP4a modulates Kv4 function in a clamping fashion similar to that shown by KChIP1. Injection of Kv4.3 T1 zinc mutants into Xenopus oocytes resulted in the nonfunctional expression of Kv4.3 channels. Coexpression of Kv4.3 zinc mutants with WT KChIP4a gave rise to the functional expression of Kv4.3 current. Oocyte surface labeling results confirm the correlation between functional rescue and enhanced surface expression of zinc mutant proteins. Chimeric mutations that replace the Kv4.3 N-terminus with N-terminal KChIP4a or N-terminal deletion of KChIP4a further demonstrate that the functional rescue of Kv4.3 channel tetramerization mutants depends on the KChIP4a core region, but not its N-terminus. Structure-guided mutation of two critical residues of core KChIP4a attenuated functional rescue and tetrameric assembly. Moreover, size exclusion chromatography combined with fast protein liquid chromatography showed that KChIP4a can drive zinc mutant monomers to assemble as tetramers. Taken together, our results show that KChIP4a can rescue the function of tetramerization-defective Kv4 monomers. Therefore, we propose that core KChIP4a functions to promote tetrameric assembly and enhance surface expression of Kv4 channels by a clamping action, whereas its N-terminus inhibits surface expression of Kv4 by a mechanism that remains elusive.
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Affiliation(s)
- Ping Liang
- Department of Neurobiology, Neuroscience Research Institute, Peking University Health Science Center, Beijing, China
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Lin L, Sun W, Wikenheiser AM, Kung F, Hoffman DA. KChIP4a regulates Kv4.2 channel trafficking through PKA phosphorylation. Mol Cell Neurosci 2010; 43:315-25. [PMID: 20045463 DOI: 10.1016/j.mcn.2009.12.005] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 12/18/2009] [Accepted: 12/22/2009] [Indexed: 10/20/2022] Open
Abstract
Voltage-gated potassium (Kv) channels play important roles in regulating the excitability of myocytes and neurons. Kv4.2 is the primary alpha-subunit of the channel that produces the A-type K(+) current in CA1 pyramidal neurons of the hippocampus, which is critically involved in the regulation of dendritic excitability and plasticity. K(+) channel-interacting proteins, KChIPs (KChIP1-4), associate with the N-terminal of Kv4.2 and modulate the channel's biophysical properties, turnover rate and surface expression. In the present study, we investigated the role of Kv4.2 C-terminal PKA phosphorylation site S552 in the KChIP4a-mediated effects on Kv4.2 channel trafficking. We found that while interaction between Kv4.2 and KChIP4a does not require PKA phosphorylation of Kv4.2(S552), phosphorylation of this site is necessary for both enhanced stabilization and membrane expression of Kv4.2 channel complexes produced by KChIP4a. Enhanced surface expression and protein stability conferred by co-expression of Kv4.2 with other KChIP isoforms did not require PKA phosphorylation of Kv4.2 S552. Finally, we identify A-kinase anchoring proteins (AKAPs) as Kv4.2 binding partners, allowing for discrete local PKA signaling. These data demonstrate that PKA phosphorylation of Kv4.2 plays an important role in the trafficking of Kv4.2 through its specific interaction with KChIP4a.
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Affiliation(s)
- Lin Lin
- Molecular Neurophysiology and Biophysics Unit, Laboratory of Cellular and Synaptic Neurophysiology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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