1
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Tan JK, Arno G, Josifova D, Mohamed MD, Mahroo OA. Unusual OCT findings in a patient with CABP4-associated cone-rod synaptic disorder. Doc Ophthalmol 2024; 148:115-120. [PMID: 38206458 PMCID: PMC10954985 DOI: 10.1007/s10633-023-09961-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Accepted: 12/06/2023] [Indexed: 01/12/2024]
Abstract
PURPOSE Bi-allelic variants in CABP4 are associated with congenital cone-rod synaptic disorder, which has also been classified, electrophysiologically, as incomplete congenital stationary night blindness (iCSNB). We describe clinical findings in a patient who demonstrated an unusual macular optical coherence tomography (OCT) phenotype, not previously reported in this condition. METHODS Our patient underwent multimodal retinal imaging, international standard full-field ERG testing and whole genome sequencing. RESULTS The patient was a 60-year-old woman with non-progressive visual impairment since birth, nystagmus and preference for dim lighting. Clinical fundus examination was unremarkable. OCT imaging revealed a hypo-reflective zone under an elevated fovea in both eyes. ERGs showed an electronegative DA10 response, with severely abnormal light-adapted responses. Whole genome sequencing revealed homozygosity for a known pathogenic variant in CABP4. No variants were found in other genes that could explain the patient's phenotype. CONCLUSIONS OCT findings of foveal elevation and an underlying hypo-reflective zone are novel in this condition. Whilst the clinical history was similar to achromatopsia and other cone dysfunction syndromes, ERG findings suggested disease associated with CACNA1F or CABP4. As CACNA1F is X-linked, CABP4 was more likely, and confirmed on genetic testing. The patient saw better in dim light, confirming that night blindness is not a feature of CABP4-associated disease. Our case highlights the value of ERGs in discriminating between causes of cone dysfunction, and extends the range of retinal imaging phenotypes reported in this disorder.
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Affiliation(s)
- Jit Kai Tan
- Department of Ophthalmology, Guy's & St Thomas' NHS Foundation Trust, St Thomas' Hospital, Westminster Bridge Road, London, England
- Institute of Ophthalmology, University College London, Bath Street, London, England
| | - Gavin Arno
- Institute of Ophthalmology, University College London, Bath Street, London, England
- Retinal and Genetics Services, Moorfields Eye Hospital, City Road, London, England
| | - Dragana Josifova
- Department of Genetics, Guy's & St Thomas' NHS Foundation Trust, Guy's Hospital, London, England
| | - Moin D Mohamed
- Department of Ophthalmology, Guy's & St Thomas' NHS Foundation Trust, St Thomas' Hospital, Westminster Bridge Road, London, England
| | - Omar A Mahroo
- Department of Ophthalmology, Guy's & St Thomas' NHS Foundation Trust, St Thomas' Hospital, Westminster Bridge Road, London, England.
- Institute of Ophthalmology, University College London, Bath Street, London, England.
- Retinal and Genetics Services, Moorfields Eye Hospital, City Road, London, England.
- Section of Ophthalmology, King's College London, St Thomas' Hospital Campus, Westminster Bridge Road, London, England.
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2
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Yadav DK, Anderson DE, Hell JW, Ames JB. Calmodulin promotes a Ca 2+ -dependent conformational change in the C-terminal regulatory domain of Ca V 1.2. FEBS Lett 2022; 596:2974-2985. [PMID: 36310389 PMCID: PMC9719739 DOI: 10.1002/1873-3468.14529] [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: 09/09/2022] [Revised: 10/07/2022] [Accepted: 10/10/2022] [Indexed: 11/10/2023]
Abstract
Calmodulin (CaM) binds to the membrane-proximal cytosolic C-terminal domain of CaV 1.2 (residues 1520-1669, CT(1520-1669)) and causes Ca2+ -induced conformational changes that promote Ca2+ -dependent channel inactivation (CDI). We report biophysical studies that probe the structural interaction between CT(1520-1669) and CaM. The recombinantly expressed CT(1520-1669) is insoluble, but can be solubilized in the presence of Ca2+ -saturated CaM (Ca4 /CaM), but not in the presence of Ca2+ -free CaM (apoCaM). We show that half-calcified CaM (Ca2 /CaM12 ) forms a complex with CT(1520-1669) that is less soluble than CT(1520-1669) bound to Ca4 /CaM. The NMR spectrum of CT(1520-1669) reveals spectral differences caused by the binding of Ca2 /CaM12 versus Ca4 /CaM, suggesting that the binding of Ca2+ to the CaM N-lobe may induce a conformational change in CT(1520-1669).
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Affiliation(s)
| | - David E. Anderson
- Department of Chemistry, University of California, Davis, CA 95616, USA
| | - Johannes W. Hell
- Department of Pharmacology, University of California, Davis, CA 95616, USA
| | - James B. Ames
- Department of Chemistry, University of California, Davis, CA 95616, USA
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3
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Guo Y, Miao Q, Zhang Y, Wang C, Liang M, Li X, Qiu W, Shi G, Zhai Q, Chen Z. A novel missense creatine mutant of CaBP4, c.464G>A (p.G155D), associated with autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE), reduces the expression of CaBP4. Transl Pediatr 2022; 11:396-402. [PMID: 35378956 PMCID: PMC8976675 DOI: 10.21037/tp-22-54] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Accepted: 03/10/2022] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND CaBP4 encodes Ca2+-binding protein 4, a neuronal Ca2+-binding protein that participates in many cellular processes by regulating the concentration of free Ca2+ ions. De novo CaBP4 variants have been identified as a cause of congenital stationary night blindness (CSNB). However, we recently reported a 4-generation pedigree with 11 individuals diagnosed with autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) that were validated with only one novel missense mutation, c.464G>A (p.G155D), in CaBP4. De novo CaBP4 variants have never been reported to be related with ADNFLE. This study aimed to identify whether c.464G>A (p.G155D) in CaBP4 reduced the expression of CaBP4. METHODS In vitro experiments using recombinant protein expressed in human neuron cells were utilized in this study. Real-time polymerase chain reaction (RT-PCR) was performed to evaluate the effect of c.464G>A on CaBP4 mRNA expression. Western blot was performed to assess the effect of c.464G>A on CaBP4 protein expression. RESULTS According to the RT-PCR and Western blot results, c.464G>A (p.G155D) was associated with an increased expression of CaBP4 mRNA and a reduced expression of CaBP4 protein. CONCLUSIONS These results reveal that c.464G>A (p.G155D) in CaBP4 reduced the expression of CaBP4 by reducing the stability of the CaBP4 protein. Mutations in the CaBP4 gene may be associated with ADNFLE.
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Affiliation(s)
- Yuxiong Guo
- Department of Pediatrics, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangdong Academy of Neuroscience, Guangzhou, China.,Second School of Clinical Medicine, Southern Medical University, Guangzhou, China
| | - Qinfei Miao
- Department of Neurology Rehabilitation, Guangdong Maternal and Child Hospital, Guangzhou, China
| | - Yuxin Zhang
- Department of Pediatrics, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangdong Academy of Neuroscience, Guangzhou, China
| | - Chun Wang
- Department of Pediatrics, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangdong Academy of Neuroscience, Guangzhou, China
| | - Mingjuan Liang
- Department of Pediatrics, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangdong Academy of Neuroscience, Guangzhou, China.,Second School of Clinical Medicine, Southern Medical University, Guangzhou, China
| | - Xueping Li
- Department of Pediatrics, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangdong Academy of Neuroscience, Guangzhou, China.,Shantou University, Shantou, China
| | - Weifeng Qiu
- Department of Pediatrics, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangdong Academy of Neuroscience, Guangzhou, China.,Shantou University, Shantou, China
| | - Gangan Shi
- Department of Pediatrics, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangdong Academy of Neuroscience, Guangzhou, China.,South China University of Technology, Guangzhou, China
| | - Qiongxiang Zhai
- Department of Pediatrics, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangdong Academy of Neuroscience, Guangzhou, China.,Second School of Clinical Medicine, Southern Medical University, Guangzhou, China
| | - Zhihong Chen
- Department of Pediatrics, Guangdong Provincial People's Hospital, Guangdong Academy of Medical Sciences, Guangdong Academy of Neuroscience, Guangzhou, China.,Second School of Clinical Medicine, Southern Medical University, Guangzhou, China
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4
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Cudia D, Roseman GP, Assafa TE, Shahu MK, Scholten A, Menke-Sell SK, Yamada H, Koch KW, Milhauser G, Ames JB. NMR and EPR-DEER Structure of a Dimeric Guanylate Cyclase Activator Protein-5 from Zebrafish Photoreceptors. Biochemistry 2021; 60:3058-3070. [PMID: 34609135 DOI: 10.1021/acs.biochem.1c00612] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Retinal guanylate cyclases (RetGCs) are regulated by a family of guanylate cyclase-activating proteins (called GCAP1-7). GCAPs form dimers that bind to Ca2+ and confer Ca2+ sensitive activation of RetGC during visual phototransduction. The GCAP5 homologue from zebrafish contains two nonconserved cysteine residues (Cys15 and Cys17) that bind to ferrous ion, which stabilizes GCAP5 dimerization and diminishes its ability to activate RetGC. Here, we present NMR and EPR-DEER structural analysis of a GCAP5 dimer in the Mg2+-bound, Ca2+-free, Fe2+-free activator state. The NMR-derived structure of GCAP5 is similar to the crystal structure of Ca2+-bound GCAP1 (root-mean-square deviation of 2.4 Å), except that the N-terminal helix of GCAP5 is extended by two residues, which allows the sulfhydryl groups of Cys15 and Cys17 to become more solvent exposed in GCAP5 to facilitate Fe2+ binding. Nitroxide spin-label probes were covalently attached to particular cysteine residues engineered in GCAP5: C15, C17, T26C, C28, N56C, C69, C105, N139C, E152C, and S159C. The intermolecular distance of each spin-label probe in dimeric GCAP5 (measured by EPR-DEER) defined restraints for calculating the dimer structure by molecular docking. The GCAP5 dimer possesses intermolecular hydrophobic contacts involving the side chain atoms of H18, Y21, M25, F72, V76, and W93, as well as an intermolecular salt bridge between R22 and D71. The structural model of the GCAP5 dimer was validated by mutations (H18E/Y21E, H18A/Y21A, R22D, R22A, M25E, D71R, F72E, and V76E) at the dimer interface that disrupt dimerization of GCAP5 and affect the activation of RetGC. We propose that GCAP5 dimerization may play a role in the Fe2+-dependent regulation of cyclase activity in zebrafish photoreceptors.
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Affiliation(s)
- Diana Cudia
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Graham P Roseman
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
| | - Tufa E Assafa
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
| | - Manisha Kumari Shahu
- Division of Biochemistry, Department of Neuroscience, University of Oldenburg, 26129 Oldenburg, Germany
| | - Alexander Scholten
- Division of Biochemistry, Department of Neuroscience, University of Oldenburg, 26129 Oldenburg, Germany
| | - Sarah-Karina Menke-Sell
- Division of Biochemistry, Department of Neuroscience, University of Oldenburg, 26129 Oldenburg, Germany
| | - Hiroaki Yamada
- Department of Chemistry, University of California, Davis, California 95616, United States
| | - Karl-W Koch
- Division of Biochemistry, Department of Neuroscience, University of Oldenburg, 26129 Oldenburg, Germany
| | - Glenn Milhauser
- Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, United States
| | - James B Ames
- Department of Chemistry, University of California, Davis, California 95616, United States
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5
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Koschak A, Fernandez-Quintero ML, Heigl T, Ruzza M, Seitter H, Zanetti L. Cav1.4 dysfunction and congenital stationary night blindness type 2. Pflugers Arch 2021; 473:1437-1454. [PMID: 34212239 PMCID: PMC8370969 DOI: 10.1007/s00424-021-02570-x] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 04/14/2021] [Accepted: 04/18/2021] [Indexed: 12/04/2022]
Abstract
Cav1.4 L-type Ca2+ channels are predominantly expressed in retinal neurons, particularly at the photoreceptor terminals where they mediate sustained Ca2+ entry needed for continuous neurotransmitter release at their ribbon synapses. Cav1.4 channel gating properties are controlled by accessory subunits, associated regulatory proteins, and also alternative splicing. In humans, mutations in the CACNA1F gene encoding for Cav1.4 channels are associated with X-linked retinal disorders such as congenital stationary night blindness type 2. Mutations in the Cav1.4 protein result in a spectrum of altered functional channel activity. Several mouse models broadened our understanding of the role of Cav1.4 channels not only as Ca2+ source at retinal synapses but also as synaptic organizers. In this review, we highlight different structural and functional phenotypes of Cav1.4 mutations that might also occur in patients with congenital stationary night blindness type 2. A further important yet mostly neglected aspect that we discuss is the influence of alternative splicing on channel dysfunction. We conclude that currently available functional phenotyping strategies should be refined and summarize potential specific therapeutic options for patients carrying Cav1.4 mutations. Importantly, the development of new therapeutic approaches will permit a deeper understanding of not only the disease pathophysiology but also the physiological function of Cav1.4 channels in the retina.
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MESH Headings
- 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester/pharmacology
- Animals
- Calcium Channel Agonists/pharmacology
- Calcium Channels, L-Type/genetics
- Calcium Channels, L-Type/metabolism
- Eye Diseases, Hereditary/genetics
- Eye Diseases, Hereditary/metabolism
- Genetic Diseases, X-Linked/genetics
- Genetic Diseases, X-Linked/metabolism
- Humans
- Mutation/physiology
- Myopia/genetics
- Myopia/metabolism
- Night Blindness/genetics
- Night Blindness/metabolism
- Retina/drug effects
- Retina/metabolism
- Synapses/drug effects
- Synapses/genetics
- Synapses/metabolism
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Affiliation(s)
- Alexandra Koschak
- Institute of Pharmacy, Pharmacology and Toxicology, Center for Chemistry and Biomedicine, University of Innsbruck, Innrain 80-82/III, 6020, Innsbruck, Austria.
| | - Monica L Fernandez-Quintero
- Institute of General, Inorganic and Theoretical Chemistry, Center for Chemistry and Biomedicine, University of Innsbruck, Innrain 80-82/III, 6020, Innsbruck, Austria
| | - Thomas Heigl
- Institute of Pharmacy, Pharmacology and Toxicology, Center for Chemistry and Biomedicine, University of Innsbruck, Innrain 80-82/III, 6020, Innsbruck, Austria
| | - Marco Ruzza
- Institute of Pharmacy, Pharmacology and Toxicology, Center for Chemistry and Biomedicine, University of Innsbruck, Innrain 80-82/III, 6020, Innsbruck, Austria
| | - Hartwig Seitter
- Institute of Pharmacy, Pharmacology and Toxicology, Center for Chemistry and Biomedicine, University of Innsbruck, Innrain 80-82/III, 6020, Innsbruck, Austria
| | - Lucia Zanetti
- Institute of Pharmacy, Pharmacology and Toxicology, Center for Chemistry and Biomedicine, University of Innsbruck, Innrain 80-82/III, 6020, Innsbruck, Austria
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6
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Wang S, Cortes CJ. Interactions with PDZ proteins diversify voltage-gated calcium channel signaling. J Neurosci Res 2020; 99:332-348. [PMID: 32476168 DOI: 10.1002/jnr.24650] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Revised: 04/29/2020] [Accepted: 05/07/2020] [Indexed: 11/12/2022]
Abstract
Voltage-gated Ca2+ (CaV ) channels are crucial for neuronal excitability and synaptic transmission upon depolarization. Their properties in vivo are modulated by their interaction with a variety of scaffolding proteins. Such interactions can influence the function and localization of CaV channels, as well as their coupling to intracellular second messengers and regulatory pathways, thus amplifying their signaling potential. Among these scaffolding proteins, a subset of PDZ (postsynaptic density-95, Drosophila discs-large, and zona occludens)-domain containing proteins play diverse roles in modulating CaV channel properties. At the presynaptic terminal, PDZ proteins enrich CaV channels in the active zone, enabling neurotransmitter release by maintaining a tight and vital link between channels and vesicles. In the postsynaptic density, these interactions are essential in regulating dendritic spine morphology and postsynaptic signaling cascades. In this review, we highlight the studies that demonstrate dynamic regulations of neuronal CaV channels by PDZ proteins. We discuss the role of PDZ proteins in controlling channel activity, regulating channel cell surface density, and influencing channel-mediated downstream signaling events. We highlight the importance of PDZ protein regulations of CaV channels and evaluate the link between this regulatory effect and human disease.
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Affiliation(s)
- Shiyi Wang
- Department of Cell Biology, Duke University, Durham, NC, USA.,Department of Neurology, Duke University, Durham, NC, USA
| | - Constanza J Cortes
- Department of Neurology, Duke University, Durham, NC, USA.,Department of Cell, Developmental and Integrative Biology, University of Alabama Birmingham, Birmingham, AL, USA
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7
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Van Hook MJ, Nawy S, Thoreson WB. Voltage- and calcium-gated ion channels of neurons in the vertebrate retina. Prog Retin Eye Res 2019; 72:100760. [PMID: 31078724 PMCID: PMC6739185 DOI: 10.1016/j.preteyeres.2019.05.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 04/25/2019] [Accepted: 05/01/2019] [Indexed: 02/06/2023]
Abstract
In this review, we summarize studies investigating the types and distribution of voltage- and calcium-gated ion channels in the different classes of retinal neurons: rods, cones, horizontal cells, bipolar cells, amacrine cells, interplexiform cells, and ganglion cells. We discuss differences among cell subtypes within these major cell classes, as well as differences among species, and consider how different ion channels shape the responses of different neurons. For example, even though second-order bipolar and horizontal cells do not typically generate fast sodium-dependent action potentials, many of these cells nevertheless possess fast sodium currents that can enhance their kinetic response capabilities. Ca2+ channel activity can also shape response kinetics as well as regulating synaptic release. The L-type Ca2+ channel subtype, CaV1.4, expressed in photoreceptor cells exhibits specific properties matching the particular needs of these cells such as limited inactivation which allows sustained channel activity and maintained synaptic release in darkness. The particular properties of K+ and Cl- channels in different retinal neurons shape resting membrane potentials, response kinetics and spiking behavior. A remaining challenge is to characterize the specific distributions of ion channels in the more than 100 individual cell types that have been identified in the retina and to describe how these particular ion channels sculpt neuronal responses to assist in the processing of visual information by the retina.
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Affiliation(s)
- Matthew J Van Hook
- Truhlsen Eye Institute, Department of Ophthalmology & Visual Sciences, University of Nebraska Medical Center, Omaha, NE, USA
| | - Scott Nawy
- Truhlsen Eye Institute, Department of Ophthalmology & Visual Sciences, University of Nebraska Medical Center, Omaha, NE, USA; Department Pharmacology & Experimental Neuroscience(2), University of Nebraska Medical Center, Omaha, NE, USA
| | - Wallace B Thoreson
- Truhlsen Eye Institute, Department of Ophthalmology & Visual Sciences, University of Nebraska Medical Center, Omaha, NE, USA; Department Pharmacology & Experimental Neuroscience(2), University of Nebraska Medical Center, Omaha, NE, USA.
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8
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Burgoyne RD, Helassa N, McCue HV, Haynes LP. Calcium Sensors in Neuronal Function and Dysfunction. Cold Spring Harb Perspect Biol 2019; 11:cshperspect.a035154. [PMID: 30833454 DOI: 10.1101/cshperspect.a035154] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Calcium signaling in neurons as in other cell types can lead to varied changes in cellular function. Neuronal Ca2+ signaling processes have also become adapted to modulate the function of specific pathways over a wide variety of time domains and these can have effects on, for example, axon outgrowth, neuronal survival, and changes in synaptic strength. Ca2+ also plays a key role in synapses as the trigger for fast neurotransmitter release. Given its physiological importance, abnormalities in neuronal Ca2+ signaling potentially underlie many different neurological and neurodegenerative diseases. The mechanisms by which changes in intracellular Ca2+ concentration in neurons can bring about diverse responses is underpinned by the roles of ubiquitous or specialized neuronal Ca2+ sensors. It has been established that synaptotagmins have key functions in neurotransmitter release, and, in addition to calmodulin, other families of EF-hand-containing neuronal Ca2+ sensors, including the neuronal calcium sensor (NCS) and the calcium-binding protein (CaBP) families, play important physiological roles in neuronal Ca2+ signaling. It has become increasingly apparent that these various Ca2+ sensors may also be crucial for aspects of neuronal dysfunction and disease either indirectly or directly as a direct consequence of genetic variation or mutations. An understanding of the molecular basis for the regulation of the targets of the Ca2+ sensors and the physiological roles of each protein in identified neurons may contribute to future approaches to the development of treatments for a variety of human neuronal disorders.
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Affiliation(s)
- Robert D Burgoyne
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Nordine Helassa
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
| | - Hannah V McCue
- Centre for Genomic Research, University of Liverpool, Liverpool, United Kingdom
| | - Lee P Haynes
- Department of Cellular and Molecular Physiology, Institute of Translational Medicine, University of Liverpool, Liverpool, United Kingdom
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9
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Pangrsic T, Singer JH, Koschak A. Voltage-Gated Calcium Channels: Key Players in Sensory Coding in the Retina and the Inner Ear. Physiol Rev 2019; 98:2063-2096. [PMID: 30067155 DOI: 10.1152/physrev.00030.2017] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Calcium influx through voltage-gated Ca (CaV) channels is the first step in synaptic transmission. This review concerns CaV channels at ribbon synapses in primary sense organs and their specialization for efficient coding of stimuli in the physical environment. Specifically, we describe molecular, biochemical, and biophysical properties of the CaV channels in sensory receptor cells of the retina, cochlea, and vestibular apparatus, and we consider how such properties might change over the course of development and contribute to synaptic plasticity. We pay particular attention to factors affecting the spatial arrangement of CaV channels at presynaptic, ribbon-type active zones, because the spatial relationship between CaV channels and release sites has been shown to affect synapse function critically in a number of systems. Finally, we review identified synaptopathies affecting sensory systems and arising from dysfunction of L-type, CaV1.3, and CaV1.4 channels or their protein modulatory elements.
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Affiliation(s)
- Tina Pangrsic
- Synaptic Physiology of Mammalian Vestibular Hair Cells Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen and Auditory Neuroscience Group, Max Planck Institute of Experimental Medicine , Göttingen, Germany ; Department of Biology, University of Maryland , College Park, Maryland ; and Pharmacology and Toxicology, Institute of Pharmacy, University of Innsbruck , Innsbruck , Austria
| | - Joshua H Singer
- Synaptic Physiology of Mammalian Vestibular Hair Cells Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen and Auditory Neuroscience Group, Max Planck Institute of Experimental Medicine , Göttingen, Germany ; Department of Biology, University of Maryland , College Park, Maryland ; and Pharmacology and Toxicology, Institute of Pharmacy, University of Innsbruck , Innsbruck , Austria
| | - Alexandra Koschak
- Synaptic Physiology of Mammalian Vestibular Hair Cells Group, Institute for Auditory Neuroscience and InnerEarLab, University Medical Center Göttingen and Auditory Neuroscience Group, Max Planck Institute of Experimental Medicine , Göttingen, Germany ; Department of Biology, University of Maryland , College Park, Maryland ; and Pharmacology and Toxicology, Institute of Pharmacy, University of Innsbruck , Innsbruck , Austria
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10
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Waldner DM, Bech-Hansen NT, Stell WK. Channeling Vision: Ca V1.4-A Critical Link in Retinal Signal Transmission. BIOMED RESEARCH INTERNATIONAL 2018; 2018:7272630. [PMID: 29854783 PMCID: PMC5966690 DOI: 10.1155/2018/7272630] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 02/15/2018] [Indexed: 01/09/2023]
Abstract
Voltage-gated calcium channels (VGCC) are key to many biological functions. Entry of Ca2+ into cells is essential for initiating or modulating important processes such as secretion, cell motility, and gene transcription. In the retina and other neural tissues, one of the major roles of Ca2+-entry is to stimulate or regulate exocytosis of synaptic vesicles, without which synaptic transmission is impaired. This review will address the special properties of one L-type VGCC, CaV1.4, with particular emphasis on its role in transmission of visual signals from rod and cone photoreceptors (hereafter called "photoreceptors," to the exclusion of intrinsically photoreceptive retinal ganglion cells) to the second-order retinal neurons, and the pathological effects of mutations in the CACNA1F gene which codes for the pore-forming α1F subunit of CaV1.4.
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Affiliation(s)
- D. M. Waldner
- Department of Neuroscience, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - N. T. Bech-Hansen
- Department of Medical Genetics and Department of Surgery, Alberta Children's Hospital Research Institute, and Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - W. K. Stell
- Department of Cell Biology and Anatomy and Department of Surgery, Hotchkiss Brain Institute, and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
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11
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Chen ZH, Wang C, Zhuo MQ, Zhai QX, Chen Q, Guo YX, Zhang YX, Gui J, Tang ZH, Zeng XL. Exome sequencing identified a novel missense mutation c.464G>A (p.G155D) in Ca 2+-binding protein 4 ( CABP4) in a Chinese pedigree with autosomal dominant nocturnal frontal lobe epilepsy. Oncotarget 2017; 8:78940-78947. [PMID: 29108277 PMCID: PMC5668010 DOI: 10.18632/oncotarget.20694] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 05/23/2017] [Indexed: 11/25/2022] Open
Abstract
The aim of this study was to identify disease-causing gene mutations in a Chinese family affected with autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE), a 4-generation pedigree of 27 members in the Southern Chinese Han population, including 11 individuals diagnosed with ADNFLE. DNA samples were collected from 15 family members, chinese han people, including seven affected and eight unaffected individuals. None of these patients had night blindness or visual disorders. Four affected individuals were screened for mutations using whole-exome sequencing, and 13 potentially interesting mutations shared by all the four affected individuals were validated using the Sanger sequencing method. Only one novel missense mutation c.464G>A (p.G155D) in the CABP4 gene, encoding the neuronal Ca2+-binding protein 4 (CaBP4), was present in all seven affected individuals in this family as revealed by PCR with blood DNA samples using CABP4 primers. The mutation was also found in one young unaffected family member, but was absent from 300 unrelated control subjects. The p.G155D mutation, located near the Ca2+ binding motif EF-hand 1 and the L-type Ca2+ channel (Cav1.4) binding motif within the N-terminal lobe of CaBP4, is predicted to affect protein function according to the bioinformatics tools PolyPhen-2 and SIFT. These findings suggest that mutations in the CABP4 gene may be linked to ADNFLE.
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Affiliation(s)
- Zhi-Hong Chen
- Department of Pediatrics, Guangdong General Hospital, Guangdong Academy of Neuroscience, Guangdong Academy of Medical Sciences, Guangzhou 510080, China
| | - Chun Wang
- Department of Pediatrics, Guangdong General Hospital, Guangdong Academy of Neuroscience, Guangdong Academy of Medical Sciences, Guangzhou 510080, China
| | - Mu-Qing Zhuo
- Department of Pediatrics, Guangdong General Hospital, Guangdong Academy of Neuroscience, Guangdong Academy of Medical Sciences, Guangzhou 510080, China
| | - Qiong-Xiang Zhai
- Department of Pediatrics, Guangdong General Hospital, Guangdong Academy of Neuroscience, Guangdong Academy of Medical Sciences, Guangzhou 510080, China
| | - Qian Chen
- Department of Pediatrics, Guangdong General Hospital, Guangdong Academy of Neuroscience, Guangdong Academy of Medical Sciences, Guangzhou 510080, China
| | - Yu-Xiong Guo
- Department of Pediatrics, Guangdong General Hospital, Guangdong Academy of Neuroscience, Guangdong Academy of Medical Sciences, Guangzhou 510080, China
| | - Yu-Xin Zhang
- Department of Pediatrics, Guangdong General Hospital, Guangdong Academy of Neuroscience, Guangdong Academy of Medical Sciences, Guangzhou 510080, China
| | - Juan Gui
- Department of Pediatrics, Guangdong General Hospital, Guangdong Academy of Neuroscience, Guangdong Academy of Medical Sciences, Guangzhou 510080, China
| | - Zhi-Hong Tang
- Department of Pediatrics, Guangdong General Hospital, Guangdong Academy of Neuroscience, Guangdong Academy of Medical Sciences, Guangzhou 510080, China
| | - Xiao-Lu Zeng
- Department of Pediatrics, Guangdong General Hospital, Guangdong Academy of Neuroscience, Guangdong Academy of Medical Sciences, Guangzhou 510080, China
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Lim S, Peshenko IV, Olshevskaya EV, Dizhoor AM, Ames JB. Structure of Guanylyl Cyclase Activator Protein 1 (GCAP1) Mutant V77E in a Ca2+-free/Mg2+-bound Activator State. J Biol Chem 2015; 291:4429-41. [PMID: 26703466 DOI: 10.1074/jbc.m115.696161] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Indexed: 12/27/2022] Open
Abstract
GCAP1, a member of the neuronal calcium sensor subclass of the calmodulin superfamily, confers Ca(2+)-sensitive activation of retinal guanylyl cyclase 1 (RetGC1). We present NMR resonance assignments, residual dipolar coupling data, functional analysis, and a structural model of GCAP1 mutant (GCAP1(V77E)) in the Ca(2+)-free/Mg(2+)-bound state. NMR chemical shifts and residual dipolar coupling data reveal Ca(2+)-dependent differences for residues 170-174. An NMR-derived model of GCAP1(V77E) contains Mg(2+) bound at EF2 and looks similar to Ca(2+) saturated GCAP1 (root mean square deviations = 2.0 Å). Ca(2+)-dependent structural differences occur in the fourth EF-hand (EF4) and adjacent helical region (residues 164-174 called the Ca(2+) switch helix). Ca(2+)-induced shortening of the Ca(2+) switch helix changes solvent accessibility of Thr-171 and Leu-174 that affects the domain interface. Although the Ca(2+) switch helix is not part of the RetGC1 binding site, insertion of an extra Gly residue between Ser-173 and Leu-174 as well as deletion of Arg-172, Ser-173, or Leu-174 all caused a decrease in Ca(2+) binding affinity and abolished RetGC1 activation. We conclude that Ca(2+)-dependent conformational changes in the Ca(2+) switch helix are important for activating RetGC1 and provide further support for a Ca(2+)-myristoyl tug mechanism.
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Affiliation(s)
- Sunghyuk Lim
- From the Department of Chemistry, University of California, Davis, California 95616 and
| | - Igor V Peshenko
- Department of Research, Salus University, Elkins Park, Pennsylvania 19027
| | | | | | - James B Ames
- From the Department of Chemistry, University of California, Davis, California 95616 and
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