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Liu Z, Li K, Wang K, Zhang L, Jia S, Wang H, Jian F, Wu H. Knockdown of best1 Gene in Zebrafish Caused Abnormal Neuronal and Skeletal Development - A Subtype of Craniovertebral Junction Malformation? Neurospine 2024; 21:555-564. [PMID: 38317543 PMCID: PMC11224734 DOI: 10.14245/ns.2347238.619] [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: 11/21/2023] [Revised: 12/18/2023] [Accepted: 12/27/2023] [Indexed: 02/07/2024] Open
Abstract
OBJECTIVE To investigate the developmental defects caused by knockdown of best1 gene in zebrafish as a model for a subtype of craniovertebral junction (CVJ) malformation. METHODS Two antisense morpholinos (MOs) were designed targeting zebrafish best1 to block translation (ATG-MO) or to disrupt splicing (I3E4-MO). MOs were microinjected into fertilized one-cell embryos. Efficacy of splicing MO was confirmed by reverse transcription-polymerase chain reaction. Phenotypes were analyzed and quantified by microscopy at multiple developmental stages. Neuronal outgrowth was assessed in transgenic zebrafish expressing green fluorescent protein in neurons. Skeletal ossification was visualized by Calcein staining. RESULTS Knockdown of best1 resulted in zebrafish embryos with shorter body length, curved axis, low survival rate, microcephaly, reduced eye size, smaller head and brain, impaired neuronal outgrowth, and reduced ossification of craniofacial and vertebral bone. CONCLUSION Best1 gene plays critical roles in ophthalmologic, neurological and skeletal development in zebrafish. A patient with a premature stop codon in BEST1 gene exhibited similar phenotypes, implying a subtype of CVJ malformation.
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Affiliation(s)
- Zhenlei Liu
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, Beijing, China
- Spine Center, China International Neuroscience Institute (China-INI), Beijing, China
| | - Kang Li
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, Beijing, China
- Spine Center, China International Neuroscience Institute (China-INI), Beijing, China
| | - Kai Wang
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, Beijing, China
- Spine Center, China International Neuroscience Institute (China-INI), Beijing, China
| | - Lei Zhang
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, Beijing, China
- Spine Center, China International Neuroscience Institute (China-INI), Beijing, China
| | - Shanhang Jia
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, Beijing, China
- Spine Center, China International Neuroscience Institute (China-INI), Beijing, China
| | - He Wang
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, Beijing, China
- Spine Center, China International Neuroscience Institute (China-INI), Beijing, China
| | - Fengzeng Jian
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, Beijing, China
- Spine Center, China International Neuroscience Institute (China-INI), Beijing, China
| | - Hao Wu
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, Beijing, China
- Spine Center, China International Neuroscience Institute (China-INI), Beijing, China
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Tekin K, Dulger SC, Horozoglu Ceran T, Inanc M, Ozdal PC, Teke MY. Multimodal imaging and genetic characteristics of autosomal recessive bestrophinopathy. J Fr Ophtalmol 2024; 47:104097. [PMID: 38518704 DOI: 10.1016/j.jfo.2024.104097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Revised: 08/30/2023] [Accepted: 10/11/2023] [Indexed: 03/24/2024]
Abstract
PURPOSE To report the ocular manifestations, multimodal imaging characteristics and genetic testing results of six patients with autosomal recessive bestrophinopathy (ARB). METHODS This was an observational case series including 12 eyes of 6 patients who were diagnosed with ARB. All patients underwent a complete ophthalmic examination including refraction, slit-lamp biomicroscopy, dilated fundus examination, fundus autofluorescence, optical coherence tomography and electrooculography. BEST1 gene sequencing was also performed for all patients. RESULTS The mean age was 22.8years and the male-female ratio was 0.50. All ARB patients had a hyperopic refractive error. A spectrum of fundus abnormalities, including multifocal yellowish subretinal deposits in the posterior pole, subfoveal accumulation of vitelliform material and cystoid macular edema, was observed. Fundus autofluorescence imaging demonstrated marked hyperautofluorescence corresponding to the yellowish subretinal deposits. Optical coherence tomography revealed serous retinal detachment, intraretinal cysts, brush border appearance caused by elongation of the outer segments of photoreceptors, and hyperreflective dome-shaped deposits at the level of the retinal pigment epithelium. Fundus fluorescein angiography showed hyperfluorescence with staining of the yellowish subretinal deposits. Electrooculography showed reduced Arden ratio in all patients. In addition, biallelic pathogenic variants in the BEST1 gene were detected in all patients. CONCLUSION ARB is a rare autosomal recessive inherited retinal disorder with biallelic pathogenic variants in the BEST1 gene and may present with a wide range of ocular abnormalities that may not be easily diagnosed. Multimodal retinal imaging in conjunction with EOG is helpful to establish the correct diagnosis.
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Affiliation(s)
- K Tekin
- Department of Ophthalmology, Ulucanlar Eye Training and Research Hospital, Ankara, Turkey.
| | - S C Dulger
- Department of Ophthalmology, Ulucanlar Eye Training and Research Hospital, Ankara, Turkey
| | - T Horozoglu Ceran
- Department of Ophthalmology, Ulucanlar Eye Training and Research Hospital, Ankara, Turkey
| | - M Inanc
- Department of Ophthalmology, Ulucanlar Eye Training and Research Hospital, Ankara, Turkey
| | - P C Ozdal
- Department of Ophthalmology, Ulucanlar Eye Training and Research Hospital, Ankara, Turkey
| | - M Y Teke
- Department of Ophthalmology, Ulucanlar Eye Training and Research Hospital, Ankara, Turkey
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Hussain N, Apotikar A, Pidathala S, Mukherjee S, Burada AP, Sikdar SK, Vinothkumar KR, Penmatsa A. Cryo-EM structures of pannexin 1 and 3 reveal differences among pannexin isoforms. Nat Commun 2024; 15:2942. [PMID: 38580658 PMCID: PMC10997603 DOI: 10.1038/s41467-024-47142-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2022] [Accepted: 03/19/2024] [Indexed: 04/07/2024] Open
Abstract
Pannexins are single-membrane large-pore channels that release ions and ATP upon activation. Three isoforms of pannexins 1, 2, and 3, perform diverse cellular roles and differ in their pore lining residues. In this study, we report the cryo-EM structure of pannexin 3 at 3.9 Å and analyze its structural differences with pannexin isoforms 1 and 2. The pannexin 3 vestibule has two distinct chambers and a wider pore radius in comparison to pannexins 1 and 2. We further report two cryo-EM structures of pannexin 1, with pore substitutions W74R/R75D that mimic the pore lining residues of pannexin 2 and a germline mutant of pannexin 1, R217H at resolutions of 3.2 Å and 3.9 Å, respectively. Substitution of cationic residues in the vestibule of pannexin 1 results in reduced ATP interaction propensities to the channel. The germline mutant R217H in transmembrane helix 3 (TM3), leads to a partially constricted pore, reduced ATP interaction and weakened voltage sensitivity. The study compares the three pannexin isoform structures, the effects of substitutions of pore and vestibule-lining residues and allosteric effects of a pathological substitution on channel structure and function thereby enhancing our understanding of this vital group of ATP-release channels.
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Affiliation(s)
- Nazia Hussain
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India
| | - Ashish Apotikar
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India
| | - Shabareesh Pidathala
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India
- St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Sourajit Mukherjee
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India
- Department of Chemistry, The University of Chicago, Chicago, USA
| | - Ananth Prasad Burada
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India
| | - Sujit Kumar Sikdar
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India
| | - Kutti R Vinothkumar
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, 560065, India
| | - Aravind Penmatsa
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India.
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4
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Bianco L, Arrigo A, Antropoli A, Del Fabbro S, Mauro L, Pina A, Bandello F, Battaglia Parodi M. The Retinal Phenotype Associated with the p.Pro101Thr BEST1 Variant. Ophthalmol Retina 2024; 8:288-297. [PMID: 37717827 DOI: 10.1016/j.oret.2023.09.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 08/29/2023] [Accepted: 09/11/2023] [Indexed: 09/19/2023]
Abstract
PURPOSE To describe the retinal phenotype associated with the p.Pro101Thr BEST1 variant. DESIGN Retrospective, observational case series. PARTICIPANTS Patients diagnosed with bestrophinopathies in which molecular genetic testing identified the p.Pro101Thr BEST1 as well as healthy carriers among their first-degree relatives. METHODS Medical records were reviewed to obtain data on family history and ophthalmic examinations, including retinal imaging. The imaging protocol included OCT and fundus autofluorescence using Spectralis HRA + OCT (Heidelberg Engineering). Genetic analysis was performed by next-generation sequencing. MAIN OUTCOME MEASURES Results of ophthalmic examinations and multimodal imaging features of retinal phenotypes. RESULTS The c.301C>A, p.Pro101Thr BEST1 missense variant was identified as the causative variant in 8 individuals (all men) from 5 families, accounting for 13% of cases (8/61) and 10% of pathogenic alleles (9/93) in our cohort of patients affected by bestrophinopathies. Seven individuals (14 eyes) had the variant in heterozygous status: all eyes had a hyperopic refractive error (median spherical equivalent of + 3.75 diopters [D]) and 4 individuals had a macular dystrophy with mildly reduced visual acuity (median of 20/25 Snellen), whereas the other 3 were asymptomatic carriers. On multimodal retinal imaging, 5 (36%) out of 14 eyes had subclinical bestrophinopathy, 4 (29%) had typical findings of adult-onset foveomacular vitelliform dystrophy (AOFVD), and the remaining 5 (36%) displayed a pattern dystrophy-like phenotype. Follow-up data were available for 6 subjects, demonstrating clinical stability up to 11 years, in both subclinical and clinical forms. An additional patient with autosomal recessive bestrophinopathy was found to harbor the p.Pro101Thr variant in homozygosity. CONCLUSIONS The p.Pro101Thr BEST1 variant is likely a frequent cause of bestrophinopathy in the Italian population and can result in autosomal dominant macular dystrophies with incomplete penetrance and mild clinical manifestations as well as autosomal recessive bestrophinopathy. The spectrum of autosomal dominant maculopathy includes the typical AOFVD and a pattern dystrophy-like phenotype. FINANCIAL DISCLOSURE(S) Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.
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Affiliation(s)
- Lorenzo Bianco
- Department of Ophthalmology, Istituto di Ricerca e Cura a Carattere Scientifico (IRCCS), San Raffaele Scientific Institute, Vita-Salute San Raffaele University, Milan, Italy
| | - Alessandro Arrigo
- Department of Ophthalmology, Istituto di Ricerca e Cura a Carattere Scientifico (IRCCS), San Raffaele Scientific Institute, Vita-Salute San Raffaele University, Milan, Italy.
| | - Alessio Antropoli
- Department of Ophthalmology, Istituto di Ricerca e Cura a Carattere Scientifico (IRCCS), San Raffaele Scientific Institute, Vita-Salute San Raffaele University, Milan, Italy
| | - Sebastiano Del Fabbro
- Department of Ophthalmology, Istituto di Ricerca e Cura a Carattere Scientifico (IRCCS), San Raffaele Scientific Institute, Vita-Salute San Raffaele University, Milan, Italy
| | - Luca Mauro
- Department of Ophthalmology, Istituto di Ricerca e Cura a Carattere Scientifico (IRCCS), San Raffaele Scientific Institute, Vita-Salute San Raffaele University, Milan, Italy
| | - Adelaide Pina
- Department of Ophthalmology, Istituto di Ricerca e Cura a Carattere Scientifico (IRCCS), San Raffaele Scientific Institute, Vita-Salute San Raffaele University, Milan, Italy
| | - Francesco Bandello
- Department of Ophthalmology, Istituto di Ricerca e Cura a Carattere Scientifico (IRCCS), San Raffaele Scientific Institute, Vita-Salute San Raffaele University, Milan, Italy
| | - Maurizio Battaglia Parodi
- Department of Ophthalmology, Istituto di Ricerca e Cura a Carattere Scientifico (IRCCS), San Raffaele Scientific Institute, Vita-Salute San Raffaele University, Milan, Italy
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Medeiros-Silva J, Dregni AJ, Somberg NH, Duan P, Hong M. Atomic structure of the open SARS-CoV-2 E viroporin. SCIENCE ADVANCES 2023; 9:eadi9007. [PMID: 37831764 PMCID: PMC10575589 DOI: 10.1126/sciadv.adi9007] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Accepted: 09/08/2023] [Indexed: 10/15/2023]
Abstract
The envelope (E) protein of the SARS-CoV-2 virus forms cation-conducting channels in the endoplasmic reticulum Golgi intermediate compartment (ERGIC) of infected cells. The calcium channel activity of E is associated with the inflammatory responses of COVID-19. Using solid-state NMR (ssNMR) spectroscopy, we have determined the open-state structure of E's transmembrane domain (ETM) in lipid bilayers. Compared to the closed state, open ETM has an expansive water-filled amino-terminal chamber capped by key glutamate and threonine residues, a loose phenylalanine aromatic belt in the middle, and a constricted polar carboxyl-terminal pore filled with an arginine and a threonine residue. This structure gives insights into how protons and calcium ions are selected by ETM and how they permeate across the hydrophobic gate of this viroporin.
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Affiliation(s)
| | - Aurelio J. Dregni
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | | | - Pu Duan
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Amato A, Wongchaisuwat N, Lamborn A, Schmidt R, Everett L, Yang P, Pennesi ME. Gene therapy in bestrophinopathies: Insights from preclinical studies in preparation for clinical trials. Saudi J Ophthalmol 2023; 37:287-295. [PMID: 38155675 PMCID: PMC10752275 DOI: 10.4103/sjopt.sjopt_175_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 08/15/2023] [Accepted: 08/17/2023] [Indexed: 12/30/2023] Open
Abstract
The BEST1 gene encodes bestrophin-1, a homopentameric ion channel expressed in the retinal pigment epithelium (RPE), where it localizes to the basolateral plasma membrane. Pathogenic variants in this gene can cause different autosomal dominant and recessive inherited retinal diseases (IRDs), collectively named "bestrophinopathies." These disorders share a number of clinical and molecular features that make them an appealing target for gene therapy. Clinically, bestrophinopathies are often slowly progressive with a wide window of opportunity, and the presence of subretinal material (vitelliform deposits and/or fluid) as a hallmark of these conditions provides an easily quantifiable endpoint in view of future clinical trials. From a molecular standpoint, most BEST1 pathogenic variants have been shown to cause either loss of function (LOF) of the protein or a dominant-negative (DN) effect, with a smaller subset causing a toxic gain of function (GOF). Both LOF and DN mutations may be amenable to gene augmentation alone. On the other hand, individuals harboring GOF variants would require a combination of gene silencing and gene augmentation, which has been shown to be effective in RPE cells derived from patients with Best disease. In this article, we review the current knowledge of BEST1-related IRDs and we discuss how their molecular and clinical features are being used to design novel and promising therapeutic strategies.
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Affiliation(s)
- Alessia Amato
- Department of Ophthalmic Genetics, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Nida Wongchaisuwat
- Department of Ophthalmic Genetics, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Andrew Lamborn
- Department of Ophthalmic Genetics, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Ryan Schmidt
- Department of Ophthalmic Genetics, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Lesley Everett
- Department of Ophthalmic Genetics, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Paul Yang
- Department of Ophthalmic Genetics, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, United States of America
| | - Mark E. Pennesi
- Department of Ophthalmic Genetics, Casey Eye Institute, Oregon Health and Science University, Portland, Oregon, United States of America
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7
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Sučec I, Mammeri NE, Dregni AJ, Hong M. Rapid Determination of the Topology of Oligomeric α-Helical Membrane Proteins by Water- and Lipid-Edited Methyl NMR. J Phys Chem B 2023; 127:7518-7530. [PMID: 37606918 PMCID: PMC10893779 DOI: 10.1021/acs.jpcb.3c05295] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/23/2023]
Abstract
Single-span oligomeric α-helical transmembrane proteins are common in virus ion channels, which are targets of antiviral drugs. Knowledge about the high-resolution structures of these oligomeric α-helical bundles is so far scarce. Structure determination of these membrane proteins by solid-state NMR traditionally requires resolving and assigning protein chemical shifts and measuring many interhelical distances, which are time-consuming. To accelerate experimental structure determination, here we introduce a simple solid-state NMR approach that uses magnetization transfer from water and lipid protons to the protein. By detecting the water- and lipid-transferred intensities of the high-sensitivity methyl 13C signals of Leu, Val, and Ile residues, which are highly enriched in these membrane proteins, we can derive models of the topology of these homo-oligomeric helical bundles. The topology is specified by the positions of amino acid residues in heptad repeats and the orientations of residues relative to the channel pore, lipids, and the helical interface. We demonstrate this water- and lipid-edited methyl NMR approach on the envelope (E) protein of SARS-CoV-2, the causative agent of the COVID-19 pandemic. We show that water-edited and lipid-edited 2D 13C-13C correlation spectra can be measured with sufficient sensitivity. Even without resolving multiple residues of the same type in the NMR spectra, we can obtain the helical bundle topology. We apply these experiments to the structurally unknown E proteins of the MERS coronavirus and the human coronavirus NL63. The resulting structural topologies show interesting differences in the positions of the aromatic residues in these three E proteins, suggesting that these viroporins may have different mechanisms of activation and ion conduction.
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Affiliation(s)
- Iva Sučec
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139
| | - Nadia El Mammeri
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139
| | - Aurelio J. Dregni
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139
| | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology, 170 Albany Street, Cambridge, MA 02139
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8
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Elverson K, Freeman S, Manson F, Warwicker J. Computational Investigation of Mechanisms for pH Modulation of Human Chloride Channels. Molecules 2023; 28:5753. [PMID: 37570721 PMCID: PMC10420675 DOI: 10.3390/molecules28155753] [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: 11/29/2022] [Revised: 07/25/2023] [Accepted: 07/26/2023] [Indexed: 08/13/2023] Open
Abstract
Many transmembrane proteins are modulated by intracellular or extracellular pH. Investigation of pH dependence generally proceeds by mutagenesis of a wide set of amino acids, guided by properties such as amino-acid conservation and structure. Prediction of pKas can streamline this process, allowing rapid and effective identification of amino acids of interest with respect to pH dependence. Commencing with the calcium-activated chloride channel bestrophin 1, the carboxylate ligand structure around calcium sites relaxes in the absence of calcium, consistent with a measured lack of pH dependence. By contrast, less relaxation in the absence of calcium in TMEM16A, and maintenance of elevated carboxylate sidechain pKas, is suggested to give rise to pH-dependent chloride channel activity. This hypothesis, modulation of calcium/proton coupling and pH-dependent activity through the extent of structural relaxation, is shown to apply to the well-characterised cytosolic proteins calmodulin (pH-independent) and calbindin D9k (pH-dependent). Further application of destabilised, ionisable charge sites, or electrostatic frustration, is made to other human chloride channels (that are not calcium-activated), ClC-2, GABAA, and GlyR. Experimentally determined sites of pH modulation are readily identified. Structure-based tools for pKa prediction are freely available, allowing users to focus on mutagenesis studies, construct hypothetical proton pathways, and derive hypotheses such as the model for control of pH-dependent calcium activation through structural flexibility. Predicting altered pH dependence for mutations in ion channel disorders can support experimentation and, ultimately, clinical intervention.
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Affiliation(s)
- Kathleen Elverson
- Division of Evolution, Infection and Genomics, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK
| | - Sally Freeman
- Division of Pharmacy and Optometry, School of Health Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK
| | - Forbes Manson
- Division of Evolution, Infection and Genomics, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester M13 9PT, UK
| | - Jim Warwicker
- Division of Molecular and Cellular Function, Faculty of Biology, Medicine and Health, Manchester Institute of Biotechnology, The University of Manchester, Manchester M1 7DN, UK
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9
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Xiong S, Xiao H, Sun M, Liu Y, Gao L, Xu K, Liang H, Jiang N, Lin Y, Chang L, Wu H, Zhu D, Luo C. Glutamate-releasing BEST1 channel is a new target for neuroprotection against ischemic stroke with wide time window. Acta Pharm Sin B 2023; 13:3008-3026. [PMID: 37521872 PMCID: PMC10372917 DOI: 10.1016/j.apsb.2023.05.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2022] [Revised: 01/13/2023] [Accepted: 04/03/2023] [Indexed: 08/01/2023] Open
Abstract
Many efforts have been made to understand excitotoxicity and develop neuroprotectants for the therapy of ischemic stroke. The narrow treatment time window is still to be solved. Given that the ischemic core expanded over days, treatment with an extended time window is anticipated. Bestrophin 1 (BEST1) belongs to a bestrophin family of calcium-activated chloride channels. We revealed an increase in neuronal BEST1 expression and function within the peri-infarct from 8 to 48 h after ischemic stroke in mice. Interfering the protein expression or inhibiting the channel function of BEST1 by genetic manipulation displayed neuroprotective effects and improved motor functional deficits. Using electrophysiological recordings, we demonstrated that extrasynaptic glutamate release through BEST1 channel resulted in delayed excitotoxicity. Finally, we confirmed the therapeutic efficacy of pharmacological inhibition of BEST1 during 6-72 h post-ischemia in rodents. This delayed treatment prevented the expansion of infarct volume and the exacerbation of neurological functions. Our study identifies the glutamate-releasing BEST1 channel as a potential therapeutic target against ischemic stroke with a wide time window.
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Affiliation(s)
- Shuai Xiong
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Hui Xiao
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Meng Sun
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Yunjie Liu
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Ling Gao
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Ke Xu
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Haiying Liang
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Nan Jiang
- Department of Medicinal Chemistry, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Yuhui Lin
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Lei Chang
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
| | - Haiyin Wu
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
- Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing 211166, China
| | - Dongya Zhu
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
- Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing 211166, China
| | - Chunxia Luo
- Department of Pharmacology, School of Pharmacy, Nanjing Medical University, Nanjing 211166, China
- Collaborative Innovation Center for Cardiovascular Disease Translational Medicine, Nanjing Medical University, Nanjing 211166, China
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10
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Yang J, Chen J, Liu Y, Chen KH, Baraban JM, Qiu Z. Ventral tegmental area astrocytes modulate cocaine reward by tonically releasing GABA. Neuron 2023; 111:1104-1117.e6. [PMID: 36681074 PMCID: PMC10079641 DOI: 10.1016/j.neuron.2022.12.033] [Citation(s) in RCA: 17] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 11/30/2022] [Accepted: 12/27/2022] [Indexed: 01/21/2023]
Abstract
Addictive drugs increase ventral tegmental area (VTA) dopamine (DA) neuron activity through distinct cellular mechanisms, one of which involves disinhibition of DA neurons by inhibiting local GABA neurons. How drugs regulate VTA GABA neuron activity and drive addictive behaviors remains poorly understood. Here, we show that astrocytes control VTA GABA neuron activity in cocaine reward via tonic inhibition in mice. Repeated cocaine exposure potentiates astrocytic tonic GABA release through volume-regulated anion channels (VRACs) and augments tonic inhibition of VTA GABA neurons, thus downregulating their activities and disinhibiting nucleus accumbens (NAc) projecting DA neurons. Attenuation of tonic inhibition by either deleting Swell1 (Lrrc8a), the obligatory subunit of VRACs, in VTA astrocytes or disrupting δ subunit of GABAA receptors in VTA GABA neurons reduces cocaine-evoked changes in neuron activity, locomotion, and reward behaviors in mice. Together, our findings reveal the critical role of astrocytes in regulating the VTA local circuit and cocaine reward.
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Affiliation(s)
- Junhua Yang
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Jianan Chen
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Yongqing Liu
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Kevin Hong Chen
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Jay M Baraban
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
| | - Zhaozhu Qiu
- Department of Physiology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA; Solomon H. Snyder Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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11
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Iovino C, Ramtohul P, Au A, Romero-Morales V, Sadda S, Freund KB, Sarraf D. Vitelliform maculopathy: Diverse etiologies originating from one common pathway. Surv Ophthalmol 2023; 68:361-379. [PMID: 36720370 DOI: 10.1016/j.survophthal.2023.01.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Revised: 01/18/2023] [Accepted: 01/22/2023] [Indexed: 01/31/2023]
Abstract
Vitelliform lesions (VLs) are associated with a wide array of macular disorders but are the result of one common pathway: retinal pigment epithelium (RPE) impairment and phagocytic dysfunction. VLs are defined by the accumulation of yellowish subretinal material. In the era of multimodal advanced retinal imaging, VLs can be further characterized by subretinal hyperreflectivity with optical coherence tomography and hyperautofluorescence with fundus autofluorescence. VLs can be the result of genetic or acquired retinal diseases. In younger patients, VLs usually occur in the setting of Best disease. Additional genetic causes of VL include pattern dystrophy or adult-onset vitelliform macular dystrophy. In older patients, acquired VLs can be associated with a broad spectrum of etiologies, including tractional, paraneoplastic, toxic, and degenerative disorders. The main cause of visual morbidity in eyes with VLs is the onset of macular atrophy and macular neovascularization. Histopathological studies have provided new insights into the location, nature, and lifecycle of the vitelliform material comprised of melanosomes, lipofuscin, melanolipofuscin, and outer segment debris located between the RPE and photoreceptor layer. Impaired phagocytosis by the RPE cells is the unifying pathway leading to VL development. We discuss and summarize the nature, pathogenesis, multimodal imaging characteristics, etiologies, and natural course of vitelliform maculopathies.
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Affiliation(s)
- Claudio Iovino
- Eye Clinic, Multidisciplinary Department of Medical, Surgical and Dental Sciences, University of Campania Luigi Vanvitelli, Naples, Italy
| | - Prithvi Ramtohul
- Vitreous Retina Macula Consultants of New York, New York, NY, USA
| | - Adrian Au
- Retinal Disorders and Ophthalmic Genetics Division, Stein Eye Institute, University of California Los Angeles, Los Angeles, CA, USA
| | - Veronica Romero-Morales
- Retinal Disorders and Ophthalmic Genetics Division, Stein Eye Institute, University of California Los Angeles, Los Angeles, CA, USA
| | - SriniVas Sadda
- Doheny Image Reading Center, Doheny Eye Institute, University of California Los Angeles (UCLA) Affiliated, Los Angeles, CA, USA; Department of Ophthalmology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA, USA
| | - K Bailey Freund
- Vitreous Retina Macula Consultants of New York, New York, NY, USA; Department of Ophthalmology, NYU Grossman School of New York, New York, NY, USA
| | - David Sarraf
- Retinal Disorders and Ophthalmic Genetics Division, Stein Eye Institute, University of California Los Angeles, Los Angeles, CA, USA; Greater Los Angeles Veterans Affairs Healthcare Center, Los Angeles, CA, USA.
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12
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Miller AN, Houlihan PR, Matamala E, Cabezas-Bratesco D, Lee GY, Cristofori-Armstrong B, Dilan TL, Sanchez-Martinez S, Matthies D, Yan R, Yu Z, Ren D, Brauchi SE, Clapham DE. The SARS-CoV-2 accessory protein Orf3a is not an ion channel, but does interact with trafficking proteins. eLife 2023; 12:e84477. [PMID: 36695574 PMCID: PMC9910834 DOI: 10.7554/elife.84477] [Citation(s) in RCA: 19] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2022] [Accepted: 01/25/2023] [Indexed: 01/26/2023] Open
Abstract
The severe acute respiratory syndrome associated coronavirus 2 (SARS-CoV-2) and SARS-CoV-1 accessory protein Orf3a colocalizes with markers of the plasma membrane, endocytic pathway, and Golgi apparatus. Some reports have led to annotation of both Orf3a proteins as viroporins. Here, we show that neither SARS-CoV-2 nor SARS-CoV-1 Orf3a form functional ion conducting pores and that the conductances measured are common contaminants in overexpression and with high levels of protein in reconstitution studies. Cryo-EM structures of both SARS-CoV-2 and SARS-CoV-1 Orf3a display a narrow constriction and the presence of a positively charged aqueous vestibule, which would not favor cation permeation. We observe enrichment of the late endosomal marker Rab7 upon SARS-CoV-2 Orf3a overexpression, and co-immunoprecipitation with VPS39. Interestingly, SARS-CoV-1 Orf3a does not cause the same cellular phenotype as SARS-CoV-2 Orf3a and does not interact with VPS39. To explain this difference, we find that a divergent, unstructured loop of SARS-CoV-2 Orf3a facilitates its binding with VPS39, a HOPS complex tethering protein involved in late endosome and autophagosome fusion with lysosomes. We suggest that the added loop enhances SARS-CoV-2 Orf3a's ability to co-opt host cellular trafficking mechanisms for viral exit or host immune evasion.
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Affiliation(s)
| | | | - Ella Matamala
- Physiology Institute and Millennium Nucleus of Ion Channel-Associated Diseases, Universidad Austral de ChileValdiviaChile
| | - Deny Cabezas-Bratesco
- Physiology Institute and Millennium Nucleus of Ion Channel-Associated Diseases, Universidad Austral de ChileValdiviaChile
| | - Gi Young Lee
- Department of Biology, University of PennsylvaniaPhiladelphiaUnited States
| | | | | | | | | | - Rui Yan
- Janelia Research CampusAshburnUnited States
| | - Zhiheng Yu
- Janelia Research CampusAshburnUnited States
| | - Dejian Ren
- Department of Biology, University of PennsylvaniaPhiladelphiaUnited States
| | - Sebastian E Brauchi
- Janelia Research CampusAshburnUnited States
- Physiology Institute and Millennium Nucleus of Ion Channel-Associated Diseases, Universidad Austral de ChileValdiviaChile
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13
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Haque OI, Chandrasekaran A, Nabi F, Ahmad O, Marques JP, Ahmad T. A novel compound heterozygous BEST1 gene mutation in two siblings causing autosomal recessive bestrophinopathy. BMC Ophthalmol 2022; 22:493. [PMID: 36527004 PMCID: PMC9756692 DOI: 10.1186/s12886-022-02703-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 11/23/2022] [Indexed: 12/23/2022] Open
Abstract
PURPOSE To describe the clinical features, imaging characteristics, and genetic test results associated with a novel compound heterozygous mutation of the BEST1 gene in two siblings with autosomal recessive bestrophinopathy. METHODS Two siblings underwent a complete ophthalmic examination, including dilated fundus examination, fundus photography, fundus autofluorescence imaging, spectral-domain optical coherence tomography, fluorescein angiography, electroretinography, and electrooculography. A clinical diagnosis of autosomal recessive bestrophinopathy was established based on ocular examination and multimodal retinal imaging. Subsequently, clinical exome sequencing consisting of a panel of 6670 genes was carried out to confirm the diagnosis and assess genetic alterations in the protein-coding region of the genome of the patients. The identified mutations were tested in the two affected siblings and one of their parents. RESULTS Two siblings (a 17-year-old female and a 15-year-old male) presented with reduced visual acuity and bilaterally symmetrical subretinal deposits of hyperautofluorescent materials in the posterior pole, which showed staining in the late phase of fluorescein angiogram. Spectral-domain optical coherence tomography demonstrated hyperreflective subretinal deposits and subretinal fluid accumulation. Both patients shared two mutations in the protein-coding region of the BEST1 gene, c.103G > A, p.(Glu35Lys) and c.313C > A, p.(Arg105Ser) (a novel disease-causing mutation). Sanger sequencing confirmed that the unaffected mother of the proband was carrying p.(Glu35Lys) variant in a heterozygous state. CONCLUSIONS We have identified and described the phenotype of a novel disease-causing mutation NM_004183.4:c.313C > A, p.(Arg105Ser) in a heterozygous state along with a previously reported mutation NM_004183.4:c.103G > A, p.(Glu35Lys) of the BEST1 gene in two related patients with autosomal recessive bestrophinopathy.
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Affiliation(s)
| | | | - Faisal Nabi
- Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh, India
| | - Owais Ahmad
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, India
| | - João Pedro Marques
- Ophthalmology Unit, Centro Hospitalar E Universitário de Coimbra (CHUC), Coimbra, Portugal
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14
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Owji AP, Yu K, Kittredge A, Wang J, Zhang Y, Yang T. Bestrophin-2 and glutamine synthetase form a complex for glutamate release. Nature 2022; 611:180-187. [PMID: 36289327 PMCID: PMC9873481 DOI: 10.1038/s41586-022-05373-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Accepted: 09/21/2022] [Indexed: 01/26/2023]
Abstract
Bestrophin-2 (BEST2) is a member of the bestrophin family of calcium-activated anion channels that has a critical role in ocular physiology1-4. Here we uncover a directional permeability of BEST2 to glutamate that heavily favours glutamate exit, identify glutamine synthetase (GS) as a binding partner of BEST2 in the ciliary body of the eye, and solve the structure of the BEST2-GS complex. BEST2 reduces cytosolic GS activity by tethering GS to the cell membrane. GS extends the ion conducting pathway of BEST2 through its central cavity and inhibits BEST2 channel function in the absence of intracellular glutamate, but sensitizes BEST2 to intracellular glutamate, which promotes the opening of BEST2 and thus relieves the inhibitory effect of GS. We demonstrate the physiological role of BEST2 in conducting chloride and glutamate and the influence of GS in non-pigmented ciliary epithelial cells. Together, our results reveal a novel mechanism of glutamate release through BEST2-GS.
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Affiliation(s)
- Aaron P Owji
- Department of Ophthalmology, Columbia University, New York, NY, USA
- Department of Pharmacology, Columbia University, New York, NY, USA
| | - Kuai Yu
- Department of Cell Biology, Emory University, School of Medicine, Atlanta, GA, USA
| | - Alec Kittredge
- Department of Ophthalmology, Columbia University, New York, NY, USA
- Department of Pharmacology, Columbia University, New York, NY, USA
| | - Jiali Wang
- Department of Ophthalmology, Columbia University, New York, NY, USA
| | - Yu Zhang
- Department of Ophthalmology, Columbia University, New York, NY, USA.
| | - Tingting Yang
- Department of Ophthalmology, Columbia University, New York, NY, USA.
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15
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Lee JM, Gadhe CG, Kang H, Pae AN, Lee CJ. Glutamate Permeability of Chicken Best1. Exp Neurobiol 2022; 31:277-288. [PMID: 36351838 PMCID: PMC9659495 DOI: 10.5607/en22038] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2022] [Revised: 10/28/2022] [Accepted: 10/28/2022] [Indexed: 07/28/2023] Open
Abstract
Bestrophin-1 (Best1) is a calcium (Ca2+)-activated chloride (Cl-) channel which has a phylogenetically conserved channel structure with an aperture and neck in the ion-conducting pathway. Mammalian mouse Best1 (mBest1) has been known to have a permeability for large organic anions including gluconate, glutamate, and D-serine, in addition to several small monovalent anions, such as Cl‑, bromine (Br-), iodine (I-), and thiocyanate (SCN-). However, it is still unclear whether non-mammalian Best1 has a glutamate permeability through the ion-conducting pathway. Here, we report that chicken Best1 (cBest1) is permeable to glutamate in a Ca2+-dependent manner. The molecular docking and molecular dynamics simulation showed a glutamate binding at the aperture and neck of cBest1 and a glutamate permeation through the ion-conducting pore, respectively. Moreover, through electrophysiological recordings, we calculated the permeability ratio of glutamate to Cl- (PGlutamate/PCl) as 0.28 based on the reversal potential shift by ion substitution from Cl- to glutamate in the internal solution. Finally, we directly detected the Ca2+-dependent glutamate release through cBest1 using the ultrasensitive two-cell sniffer patch technique. Our results propose that Best1 homologs from non-mammalian (cBest1) to mammalian (mBest1) have a conserved permeability for glutamate.
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Affiliation(s)
- Jung Moo Lee
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon 34126, Korea
| | | | - Hyunji Kang
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon 34126, Korea
- IBS School, University of Science and Technology, Daejeon 34113, Korea
| | - Ae Nim Pae
- Brain Science Institute, Korea Institute of Science and Technology, Seoul 02792, Korea
- KIST School, University of Science and Technology, Seoul 02792, Korea
| | - C. Justin Lee
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea
- Center for Cognition and Sociality, Institute for Basic Science, Daejeon 34126, Korea
- IBS School, University of Science and Technology, Daejeon 34113, Korea
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16
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Hemptinne C, Willermain F, de Jong C, Postolache L, Postelmans L. Autosomal recessive bestrophinopathy associated with compound heterozygous variants in the BEST1 gene. Ophthalmic Genet 2022; 44:318-320. [PMID: 36062537 DOI: 10.1080/13816810.2022.2116649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Affiliation(s)
- Coralie Hemptinne
- Ophthalmology Department, CHU Brugmann, Université Libre de Bruxelles, Brussels, Belgium
| | - François Willermain
- Ophthalmology Department, CHU Brugmann, Université Libre de Bruxelles, Brussels, Belgium.,Ophthalmology Department, CHU Saint-Pierre, Université Libre de Bruxelles, Brussels, Belgium
| | - Casper de Jong
- Ophthalmology Department, Hôpital Universitaire des Enfants Reine Fabiola, Université Libre de Bruxelles, Brussels, Belgium
| | - Lavinia Postolache
- Ophthalmology Department, Hôpital Universitaire des Enfants Reine Fabiola, Université Libre de Bruxelles, Brussels, Belgium
| | - Laurence Postelmans
- Ophthalmology Department, CHU Brugmann, Université Libre de Bruxelles, Brussels, Belgium
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17
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Miller AN, Houlihan PR, Matamala E, Cabezas-Bratesco D, Lee GY, Cristofori-Armstrong B, Dilan TL, Sanchez-Martinez S, Matthies D, Yan R, Yu Z, Ren D, Brauchi SE, Clapham DE. The SARS-CoV-2 accessory protein Orf3a is not an ion channel, but does interact with trafficking proteins. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2022:2022.09.02.506428. [PMID: 36263072 PMCID: PMC9580380 DOI: 10.1101/2022.09.02.506428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The severe acute respiratory syndrome associated coronavirus 2 (SARS-CoV-2) and SARS-CoV-1 accessory protein Orf3a colocalizes with markers of the plasma membrane, endocytic pathway, and Golgi apparatus. Some reports have led to annotation of both Orf3a proteins as a viroporin. Here we show that neither SARS-CoV-2 nor SARS-CoV-1 form functional ion conducting pores and that the conductances measured are common contaminants in overexpression and with high levels of protein in reconstitution studies. Cryo-EM structures of both SARS-CoV-2 and SARS-CoV-1 Orf3a display a narrow constriction and the presence of a basic aqueous vestibule, which would not favor cation permeation. We observe enrichment of the late endosomal marker Rab7 upon SARS-CoV-2 Orf3a overexpression, and co-immunoprecipitation with VPS39. Interestingly, SARS-CoV-1 Orf3a does not cause the same cellular phenotype as SARS-CoV-2 Orf3a and does not interact with VPS39. To explain this difference, we find that a divergent, unstructured loop of SARS-CoV-2 Orf3a facilitates its binding with VPS39, a HOPS complex tethering protein involved in late endosome and autophagosome fusion with lysosomes. We suggest that the added loop enhances SARS-CoV-2 Orf3a ability to co-opt host cellular trafficking mechanisms for viral exit or host immune evasion.
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18
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Hall JC, Paull D, Pébay A, Lidgerwood GE. Human pluripotent stem cells for the modelling of retinal pigment epithelium homeostasis and disease: A review. Clin Exp Ophthalmol 2022; 50:667-677. [PMID: 35739648 PMCID: PMC9546239 DOI: 10.1111/ceo.14128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 06/06/2022] [Accepted: 06/19/2022] [Indexed: 12/05/2022]
Abstract
Human pluripotent stem cells (hPSCs), which include induced pluripotent stem cells and embryonic stem cells, are powerful tools for studying human development, physiology and disease, including those affecting the retina. Cells from selected individuals, or specific genetic backgrounds, can be differentiated into distinct cell types allowing the modelling of diseases in a dish for therapeutic development. hPSC‐derived retinal cultures have already been used to successfully model retinal pigment epithelium (RPE) degeneration for various retinal diseases including monogenic conditions and complex disease such as age‐related macular degeneration. Here, we will review the current knowledge gained in understanding the molecular events involved in retinal disease using hPSC‐derived retinal models, in particular RPE models. We will provide examples of various conditions to illustrate the scope of applications associated with the use of hPSC‐derived RPE models.
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Affiliation(s)
- Jenna C Hall
- Department of Anatomy and Physiology The University of Melbourne Parkville Victoria Australia
| | - Daniel Paull
- The New York Stem Cell Foundation Research Institute New York New York USA
| | - Alice Pébay
- Department of Anatomy and Physiology The University of Melbourne Parkville Victoria Australia
- Department of Surgery, Royal Melbourne Hospital The University of Melbourne Parkville Victoria Australia
| | - Grace E. Lidgerwood
- Department of Anatomy and Physiology The University of Melbourne Parkville Victoria Australia
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19
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Impaired Bestrophin Channel Activity in an iPSC-RPE Model of Best Vitelliform Macular Dystrophy (BVMD) from an Early Onset Patient Carrying the P77S Dominant Mutation. Int J Mol Sci 2022; 23:ijms23137432. [PMID: 35806438 PMCID: PMC9266689 DOI: 10.3390/ijms23137432] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 07/01/2022] [Indexed: 01/25/2023] Open
Abstract
Best Vitelliform Macular dystrophy (BVMD) is the most prevalent of the distinctive retinal dystrophies caused by mutations in the BEST1 gene. This gene, which encodes for a homopentameric calcium-activated ion channel, is crucial for the homeostasis and function of the retinal pigment epithelia (RPE), the cell type responsible for recycling the visual pigments generated by photoreceptor cells. In BVMD patients, mutations in this gene induce functional problems in the RPE cell layer with an accumulation of lipofucsin that evolves into cell death and loss of sight. In this work, we employ iPSC-RPE cells derived from a patient with the p.Pro77Ser dominant mutation to determine the correlation between this variant and the ocular phenotype. To this purpose, gene and protein expression and localization are evaluated in iPSC-RPE cells along with functional assays like phagocytosis and anion channel activity. Our cell model shows no differences in gene expression, protein expression/localization, or phagocytosis capacity, but presents an increased chloride entrance, indicating that the p.Pro77Ser variant might be a gain-of-function mutation. We hypothesize that this variant disturbs the neck region of the BEST1 channel, affecting channel function but maintaining cell homeostasis in the short term. This data shed new light on the different phenotypes of dominant mutations in BEST1, and emphasize the importance of understanding its molecular mechanisms. Furthermore, the data widen the knowledge of this pathology and open the door for a better diagnosis and prognosis of the disease.
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20
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Owji AP, Wang J, Kittredge A, Clark Z, Zhang Y, Hendrickson WA, Yang T. Structures and gating mechanisms of human bestrophin anion channels. Nat Commun 2022; 13:3836. [PMID: 35789156 PMCID: PMC9253114 DOI: 10.1038/s41467-022-31437-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 06/17/2022] [Indexed: 01/16/2023] Open
Abstract
Bestrophin-1 (Best1) and bestrophin-2 (Best2) are two members of the bestrophin family of calcium (Ca2+)-activated chloride (Cl−) channels with critical involvement in ocular physiology and direct pathological relevance. Here, we report cryo-EM structures of wild-type human Best1 and Best2 in various states at up to 1.8 Å resolution. Ca2+-bound Best1 structures illustrate partially open conformations at the two Ca2+-dependent gates of the channels, in contrast to the fully open conformations observed in Ca2+-bound Best2, which is in accord with the significantly smaller currents conducted by Best1 in electrophysiological recordings. Comparison of the closed and open states reveals a C-terminal auto-inhibitory segment (AS), which constricts the channel concentrically by wrapping around the channel periphery in an inter-protomer manner and must be released to allow channel opening. Our results demonstrate that removing the AS from Best1 and Best2 results in truncation mutants with similar activities, while swapping the AS between Best1 and Best2 results in chimeric mutants with swapped activities, underlying a key role of the AS in determining paralog specificity among bestrophins. Bestrophin channels are critical for physiology of the eye. Here, authors report cryo-EM structures of human bestrophins in various states at up to 1.8 Å resolution, revealing paralog-specific features that underlie molecular mechanisms of permeation.
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Affiliation(s)
- Aaron P Owji
- Department of Ophthalmology, Columbia University, New York, NY, USA.,Department of Pharmacology, Columbia University, New York, NY, USA
| | - Jiali Wang
- Department of Ophthalmology, Columbia University, New York, NY, USA
| | - Alec Kittredge
- Department of Ophthalmology, Columbia University, New York, NY, USA.,Department of Pharmacology, Columbia University, New York, NY, USA
| | - Zada Clark
- Department of Ophthalmology, Columbia University, New York, NY, USA
| | - Yu Zhang
- Department of Ophthalmology, Columbia University, New York, NY, USA.
| | - Wayne A Hendrickson
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY, USA. .,Department of Physiology and Cellular Biophysics, Columbia University, New York, NY, USA. .,New York Structural Biology Center, New York, NY, USA.
| | - Tingting Yang
- Department of Ophthalmology, Columbia University, New York, NY, USA.
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21
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Rozenberg A, Kaczmarczyk I, Matzov D, Vierock J, Nagata T, Sugiura M, Katayama K, Kawasaki Y, Konno M, Nagasaka Y, Aoyama M, Das I, Pahima E, Church J, Adam S, Borin VA, Chazan A, Augustin S, Wietek J, Dine J, Peleg Y, Kawanabe A, Fujiwara Y, Yizhar O, Sheves M, Schapiro I, Furutani Y, Kandori H, Inoue K, Hegemann P, Béjà O, Shalev-Benami M. Rhodopsin-bestrophin fusion proteins from unicellular algae form gigantic pentameric ion channels. Nat Struct Mol Biol 2022; 29:592-603. [PMID: 35710843 DOI: 10.1038/s41594-022-00783-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Accepted: 04/27/2022] [Indexed: 11/09/2022]
Abstract
Many organisms sense light using rhodopsins, photoreceptive proteins containing a retinal chromophore. Here we report the discovery, structure and biophysical characterization of bestrhodopsins, a microbial rhodopsin subfamily from marine unicellular algae, in which one rhodopsin domain of eight transmembrane helices or, more often, two such domains in tandem, are C-terminally fused to a bestrophin channel. Cryo-EM analysis of a rhodopsin-rhodopsin-bestrophin fusion revealed that it forms a pentameric megacomplex (~700 kDa) with five rhodopsin pseudodimers surrounding the channel in the center. Bestrhodopsins are metastable and undergo photoconversion between red- and green-absorbing or green- and UVA-absorbing forms in the different variants. The retinal chromophore, in a unique binding pocket, photoisomerizes from all-trans to 11-cis form. Heterologously expressed bestrhodopsin behaves as a light-modulated anion channel.
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Affiliation(s)
- Andrey Rozenberg
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
| | - Igor Kaczmarczyk
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Donna Matzov
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel
| | - Johannes Vierock
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Takashi Nagata
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Japan.,PRESTO, Japan Science and Technology Agency, Kawaguchi, Japan
| | - Masahiro Sugiura
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Japan
| | - Kota Katayama
- PRESTO, Japan Science and Technology Agency, Kawaguchi, Japan.,Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Japan.,OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Japan
| | - Yuma Kawasaki
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Japan
| | - Masae Konno
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Japan.,PRESTO, Japan Science and Technology Agency, Kawaguchi, Japan
| | - Yujiro Nagasaka
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Japan
| | - Mako Aoyama
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Japan
| | - Ishita Das
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot, Israel
| | - Efrat Pahima
- Fritz Haber Center for Molecular Dynamics Research Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Jonathan Church
- Fritz Haber Center for Molecular Dynamics Research Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Suliman Adam
- Fritz Haber Center for Molecular Dynamics Research Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Veniamin A Borin
- Fritz Haber Center for Molecular Dynamics Research Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Ariel Chazan
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel
| | - Sandra Augustin
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Jonas Wietek
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
| | - Julien Dine
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
| | - Yoav Peleg
- Structural Proteomics Unit (SPU), Life Sciences Core Facilities (LSCF), Weizmann Institute of Science, Rehovot, Israel
| | - Akira Kawanabe
- Laboratory of Molecular Physiology & Biophysics, Faculty of Medicine, Kagawa University, Miki-cho, Japan
| | - Yuichiro Fujiwara
- Laboratory of Molecular Physiology & Biophysics, Faculty of Medicine, Kagawa University, Miki-cho, Japan
| | - Ofer Yizhar
- Department of Neurobiology, Weizmann Institute of Science, Rehovot, Israel
| | - Mordechai Sheves
- Department of Molecular Chemistry and Materials Science, Weizmann Institute of Science, Rehovot, Israel
| | - Igor Schapiro
- Fritz Haber Center for Molecular Dynamics Research Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Yuji Furutani
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Japan.,OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Showa-ku, Japan.,OptoBioTechnology Research Center, Nagoya Institute of Technology, Showa-ku, Japan
| | - Keiichi Inoue
- The Institute for Solid State Physics, The University of Tokyo, Kashiwa, Japan
| | - Peter Hegemann
- Institute for Biology, Experimental Biophysics, Humboldt-Universität zu Berlin, Berlin, Germany
| | - Oded Béjà
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa, Israel.
| | - Moran Shalev-Benami
- Department of Chemical and Structural Biology, Weizmann Institute of Science, Rehovot, Israel.
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22
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Phan LX, Lynch CI, Crain J, Sansom MS, Tucker SJ. Influence of effective polarization on ion and water interactions within a biomimetic nanopore. Biophys J 2022; 121:2014-2026. [DOI: 10.1016/j.bpj.2022.05.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 03/25/2022] [Accepted: 05/04/2022] [Indexed: 11/16/2022] Open
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23
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Li H, Yu Z, Wang H, Wang N, Sun X, Yang S, Hua X, Liu Z. Role of ANO1 in tumors and tumor immunity. J Cancer Res Clin Oncol 2022; 148:2045-2068. [PMID: 35471604 DOI: 10.1007/s00432-022-04004-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 03/29/2022] [Indexed: 12/24/2022]
Abstract
Dysregulation of gene amplification, cell-signaling-pathway transduction, epigenetic and transcriptional regulation, and protein interactions drives tumor-cell proliferation and invasion, while ion channels also play an important role in the generation and development of tumor cells. Overexpression of Ca2+-activated Cl- channel anoctamin 1 (ANO1) is shown in numerous cancer types and correlates with poor prognosis. However, the mechanisms involved in ANO1-mediated malignant cellular transformation and the role of ANO1 in tumor immunity remain unknown. In this review, we discuss recent studies to determine the role of ANO1 in tumorigenesis and provide novel insights into the role of ANO1 in the context of tumor immunity. Furthermore, we analyze the roles and potential mechanisms of ANO1 in different types of cancers, and provide novel notions for the role of ANO1 in the tumor microenvironment and for potential use of ANO1 in clinical applications. Our review shows that ANO1 is involved in tumor immunity and microenvironment, and may, therefore, be an effective biomarker and therapeutic drug target.
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Affiliation(s)
- Haini Li
- Department of Gastroenterology, Qingdao Sixth People's Hospital, Qingdao, 266001, China
| | - Zongxue Yu
- Department of Endocrinology, Affiliated Qingdao Third People's Hospital, Qingdao University, Qingdao, 266001, China
| | - Haiyan Wang
- Department of Clinical Laboratory, Affiliated Qingdao Third People's Hospital, Qingdao University, Qingdao, 266021, China
| | - Ning Wang
- Department of Clinical Laboratory, Affiliated Qingdao Third People's Hospital, Qingdao University, Qingdao, 266021, China
| | - Xueguo Sun
- Department of Gastroenterology, Qingdao University Affiliated Hospital, Qingdao, 266001, China
| | - Shengmei Yang
- Department of Gynecology, Qingdao University Affiliated Hospital, Qingdao, 266001, China
| | - Xu Hua
- Department of Clinical Laboratory, Affiliated Qingdao Third People's Hospital, Qingdao University, Qingdao, 266021, China
| | - Zongtao Liu
- Department of Clinical Laboratory, Affiliated Qingdao Third People's Hospital, Qingdao University, Qingdao, 266021, China.
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24
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Self-organization and surface properties of hBest1 in models of biological membranes. Adv Colloid Interface Sci 2022; 302:102619. [PMID: 35276535 DOI: 10.1016/j.cis.2022.102619] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 02/19/2022] [Accepted: 02/20/2022] [Indexed: 11/22/2022]
Abstract
The transmembrane Ca2+ - activated Cl- channel - human bestrophin-1 (hBest1) is expressed in retinal pigment epithelium and mutations of BEST1 gene cause ocular degenerative diseases colectivelly referred to as "bestrophinopathies". A large number of genetical, biochemical, biophysical and molecular biological studies have been performed to understand the relationship between structure and function of the hBest1 protein and its pathophysiological significance. Here, we review the current understanding of hBest1 surface organization, interactions with membrane lipids in model membranes, and its association with microdomains of cellular membranes. These highlights are significant for modulation of channel activity in cells.
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25
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Wang C, Polovitskaya MM, Delgado BD, Jentsch TJ, Long SB. Gating choreography and mechanism of the human proton-activated chloride channel ASOR. SCIENCE ADVANCES 2022; 8:eabm3942. [PMID: 35108041 PMCID: PMC8809534 DOI: 10.1126/sciadv.abm3942] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 12/08/2021] [Indexed: 05/25/2023]
Abstract
The proton-activated chloride channel ASOR (TMEM206/PAC) permeates anions across cellular membranes in response to acidification, thereby enhancing acid-induced cell death and regulating endocytosis. The molecular mechanisms of pH-dependent control are not understood, in part because structural information for an activated conformation of ASOR is lacking. Here, we reconstitute function from purified protein and present a 3.1-Å-resolution cryo-electron microscopy structure of human ASOR at acidic pH in an activated conformation. The work contextualizes a previous acidic pH structure as a desensitized conformation. Combined with electrophysiological studies and high-resolution structures of resting and desensitized states, the work reveals mechanisms of proton sensing and ion pore gating. Clusters of extracellular acidic residues function as pH sensors and coalesce when protonated. Ensuing conformational changes induce metamorphosis of transmembrane helices to fashion an ion conduction pathway unique to the activated conformation. The studies identify a new paradigm of channel gating in this ubiquitous ion channel.
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Affiliation(s)
- Chongyuan Wang
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - Maya M. Polovitskaya
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), D-13125 Berlin, Germany
| | - Bryce D. Delgado
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
- Graduate Program in Biochemistry and Structural Biology, Cell and Developmental Biology, and Molecular Biology, Weill Cornell Medicine Graduate School of Medical Sciences, New York, NY 10065, USA
| | - Thomas J. Jentsch
- Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP) and Max-Delbrück-Centrum für Molekulare Medizin (MDC), D-13125 Berlin, Germany
- NeuroCure Cluster of Excellence, Charité Universitätsmedizin, D-10117 Berlin, Germany
| | - Stephen B. Long
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
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26
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Chowdhury S, Duvesh R, Kumaran M, Anjanamurthy R, Kumar J, Vanniarajan A, Devarajan B, Sundaresan P. Clinical reassessments and whole-exome sequencing uncover novel BEST1 mutation associated with bestrophinopathy phenotype. Ophthalmic Genet 2021; 43:191-200. [PMID: 34751623 DOI: 10.1080/13816810.2021.1998553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
BACKGROUND The diagnosis of retinal dystrophies can be challenging due to the spectrum of protean phenotypic manifestations. This study employed trio-whole-exome sequencing (trio-WES) to unveil the genetic cause of an inherited retinal disorder in a south Indian family. MATERIALS AND METHODS Proband's initial ophthalmic examinations was performed in the year 2016. WES was performed on a proband-parent trio to identify causative mutation followed by Sanger validation, segregation analysis, sequence and structure-based computational analysis to assess its pathogenicity. Based on the genetic findings, detailed clinical reassessments were performed in year 2020 for the proband and available family members. RESULTS WES revealed a novel homozygous BEST1 mutation c.G310A (p.D104N) in the proband and heterozygous for the parents, indicating autosomal recessive inheritance. Segregation analysis showed heterozygous mutation in maternal grandfather and normal genotype for younger brother and maternal grandmother. Moreover, the structure-based analysis revealed the mutation p.D104N in the cytoplasmic domain, causing structural hindrance by altering hydrogen bonds and destabilizing the BEST1 protein structure. Proband's clinical assessments were consistent with autosomal recessive bestrophinopathy (ARB) phenotype. Additionally, characteristic absent light rise and decreased light peak-to-dark trough ratio (LP:DT) was observed bilaterally in EOG. CONCLUSIONS Our study demonstrates the utility of WES and clinical re-evaluations in establishing the precise diagnosis of autosomal recessive bestrophinopathy associated with a novel mutation, thus expanding the BEST1-related mutation spectrum.
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Affiliation(s)
- Susmita Chowdhury
- Department of Genetics, Aravind Medical Research Foundation, Madurai, India.,Department of Molecular Biology, Aravind Medical Research Foundation - Affiliated to Alagappa University, Karaikudi, India
| | - Roopam Duvesh
- Department of Genetics, Aravind Medical Research Foundation, Madurai, India
| | - Manojkumar Kumaran
- Department of Bioinformatics, Aravind Medical Research Foundation, Madurai, India.,School of Chemical and Biotechnology, SASTRA (Deemed to Be University), Thanjavur, India
| | - Rupa Anjanamurthy
- Department of Paediatric Ophthalmology & Adult Strabismus Services, Aravind Eye Hospital, Madurai, India
| | - Jayant Kumar
- Department of Vitreo-Retina Services, Aravind Eye Hospital, Madurai, India
| | - Ayyasamy Vanniarajan
- Department of Molecular Genetics, Aravind Medical Research Foundation, Madurai, India
| | | | - Periasamy Sundaresan
- Department of Genetics, Aravind Medical Research Foundation, Madurai, India.,Department of Molecular Biology, Aravind Medical Research Foundation - Affiliated to Alagappa University, Karaikudi, India
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27
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Owji AP, Kittredge A, Zhang Y, Yang T. Structure and Function of the Bestrophin family of calcium-activated chloride channels. Channels (Austin) 2021; 15:604-623. [PMID: 34612806 PMCID: PMC8496536 DOI: 10.1080/19336950.2021.1981625] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
Abstract
Bestrophins are a family of calcium-activated chloride channels (CaCCs) with relevance to human physiology and a myriad of eye diseases termed "bestrophinopathies". Since the identification of bestrophins as CaCCs nearly two decades ago, extensive studies from electrophysiological and structural biology perspectives have sought to define their key channel features including calcium sensing, gating, inactivation, and anion selectivity. The initial X-ray crystallography studies on the prokaryotic homolog of Best1, Klebsiella pneumoniae (KpBest), and the Best1 homolog from Gallus gallus (chicken Best1, cBest1), laid the foundational groundwork for establishing the architecture of Best1. Recent progress utilizing single-particle cryogenic electron microscopy has further elucidated the molecular mechanism of gating in cBest1 and, separately, the structure of Best2 from Bos taurus (bovine Best2, bBest2). Meanwhile, whole-cell patch clamp, planar lipid bilayer, and other electrophysiologic analyses using these models as well as the human Best1 (hBest1) have provided ample evidence describing the functional properties of the bestrophin channels. This review seeks to consolidate these structural and functional results to paint a broad picture of the underlying mechanisms comprising the bestrophin family's structure-function relationship.
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Affiliation(s)
- Aaron P Owji
- Department of Pharmacology, Columbia University, NY, USA
| | - Alec Kittredge
- Department of Pharmacology, Columbia University, NY, USA
| | - Yu Zhang
- Department of Ophthalmology, Columbia University, NY, USA
| | - Tingting Yang
- Department of Ophthalmology, Columbia University, NY, USA
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28
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Ehsan M, Wang H, Cecchetti C, Mortensen JS, Du Y, Hariharan P, Nygaard A, Lee HJ, Ghani L, Guan L, Loland CJ, Byrne B, Kobilka BK, Chae PS. Maltose-bis(hydroxymethyl)phenol (MBPs) and Maltose-tris(hydroxymethyl)phenol (MTPs) Amphiphiles for Membrane Protein Stability. ACS Chem Biol 2021; 16:1779-1790. [PMID: 34445864 DOI: 10.1021/acschembio.1c00578] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Membrane protein structures provide a fundamental understanding of their molecular actions and are of importance for drug development. Detergents are widely used to solubilize, stabilize, and crystallize membrane proteins, but membrane proteins solubilized in conventional detergents are prone to denaturation and aggregation. Thus, developing novel detergents with enhanced efficacy for protein stabilization remains important. We report herein the design and synthesis of a class of phenol-derived maltoside detergents. Using two different linkers, we prepared two sets of new detergents, designated maltose-bis(hydroxymethyl)phenol (MBPs) and maltose-tris(hydroxymethyl)phenol (MTPs). The evaluation of these detergents with three transporters and two G-protein coupled receptors allowed us to identify a couple of new detergents (MBP-C9 and MTP-C12) that consistently conferred enhanced stability to all tested proteins compared to a gold standard detergent (DDM). Furthermore, the data analysis based on the detergent structures provides key detergent features responsible for membrane protein stabilization that together will facilitate the future design of novel detergents.
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Affiliation(s)
- Muhammad Ehsan
- Department of Bionano Engineering, Center for Bionano Intelligence Education and Research, Hanyang University, Ansan 155-88, South Korea
| | - Haoqing Wang
- Department of Molecular and Cellular Physiology, Stanford University, California 94305, United States
| | - Cristina Cecchetti
- Department of Life Sciences, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Jonas S. Mortensen
- Department of Neuroscience, University of Copenhagen, DK-2200, Copenhagen, Denmark
| | - Yang Du
- Department of Molecular and Cellular Physiology, Stanford University, California 94305, United States
| | - Parameswaran Hariharan
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas 79430, United States
| | - Andreas Nygaard
- Department of Neuroscience, University of Copenhagen, DK-2200, Copenhagen, Denmark
| | - Ho Jin Lee
- Department of Bionano Engineering, Center for Bionano Intelligence Education and Research, Hanyang University, Ansan 155-88, South Korea
| | - Lubna Ghani
- Department of Bionano Engineering, Center for Bionano Intelligence Education and Research, Hanyang University, Ansan 155-88, South Korea
| | - Lan Guan
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, Texas 79430, United States
| | - Claus J. Loland
- Department of Neuroscience, University of Copenhagen, DK-2200, Copenhagen, Denmark
| | - Bernadette Byrne
- Department of Life Sciences, Imperial College London, London, SW7 2AZ, United Kingdom
| | - Brian K. Kobilka
- Department of Molecular and Cellular Physiology, Stanford University, California 94305, United States
| | - Pil Seok Chae
- Department of Bionano Engineering, Center for Bionano Intelligence Education and Research, Hanyang University, Ansan 155-88, South Korea
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29
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Sukalskaia A, Straub MS, Deneka D, Sawicka M, Dutzler R. Cryo-EM structures of the TTYH family reveal a novel architecture for lipid interactions. Nat Commun 2021; 12:4893. [PMID: 34385445 PMCID: PMC8361169 DOI: 10.1038/s41467-021-25106-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 07/20/2021] [Indexed: 12/30/2022] Open
Abstract
The Tweety homologs (TTYHs) are members of a conserved family of eukaryotic membrane proteins that are abundant in the brain. The three human paralogs were assigned to function as anion channels that are either activated by Ca2+ or cell swelling. To uncover their unknown architecture and its relationship to function, we have determined the structures of human TTYH1–3 by cryo-electron microscopy. All structures display equivalent features of a dimeric membrane protein that contains five transmembrane segments and an extended extracellular domain. As none of the proteins shows attributes reminiscent of an anion channel, we revisited functional experiments and did not find any indication of ion conduction. Instead, we find density in an extended hydrophobic pocket contained in the extracellular domain that emerges from the lipid bilayer, which suggests a role of TTYH proteins in the interaction with lipid-like compounds residing in the membrane. The human Tweety homologue (TTYH) family of transmembrane proteins have been suggested to act as chloride channels. Here the authors present cryo-EM structures of the 3 human TTYH paralogs that do not display the expected features of an anion channel, and instead appear to interact with lipid-like compounds residing in the membrane; suggesting an involvement in lipid-associated processes.
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Affiliation(s)
| | - Monique S Straub
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Dawid Deneka
- Department of Biochemistry, University of Zurich, Zurich, Switzerland
| | - Marta Sawicka
- Department of Biochemistry, University of Zurich, Zurich, Switzerland.
| | - Raimund Dutzler
- Department of Biochemistry, University of Zurich, Zurich, Switzerland.
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30
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Hanke-Gogokhia C, Lehmann GL, Benedicto I, de la Fuente-Ortega E, Arshavsky VY, Schreiner R, Rodriguez-Boulan E. Apical CLC-2 in retinal pigment epithelium is crucial for survival of the outer retina. FASEB J 2021; 35:e21689. [PMID: 34085737 PMCID: PMC8252757 DOI: 10.1096/fj.202100349r] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Revised: 04/16/2021] [Accepted: 05/06/2021] [Indexed: 12/15/2022]
Abstract
Knockout of the chloride channel protein 2 (CLC‐2; CLCN2) results in fast progressing blindness in mice. Retinal Pigment Epithelium (RPE) and photoreceptors undergo, in parallel, rapid, and profound morphological changes and degeneration. Immunohistochemistry and electron microscopy of the outer retina and electroretinography of the CLC‐2 KO mouse demonstrated normal morphology at postnatal day 2, followed by drastic changes in RPE and photoreceptor morphology and loss of vision during the first postnatal month. To investigate whether the RPE or the photoreceptors are the primary cause of the degeneration, we injected lentiviruses carrying HA‐tagged CLC‐2 with an RPE‐specific promotor in the subretinal space of CLC‐2‐KO mice at the time of eye opening. As expected, CLC‐2‐HA was expressed exclusively in RPE; strikingly, this procedure rescued the degeneration of both RPE and photoreceptors. Light response in transduced eyes was also recovered. Only a fraction of RPE was transduced with the lentivirus; however, the entire RPE monolayer appears healthy, even the RPE cells not expressing the CLC‐2‐HA. Surprisingly, in contrast with previous physiological observations that postulate that CLC‐2 has a basolateral localization in RPE, our immunofluorescence experiments demonstrated CLC‐2 has an apical distribution, facing the subretinal space and the photoreceptor outer segments. Our findings suggest that CLC‐2 does not play the postulated role in fluid transport at the basolateral membrane. Rather, they suggest that CLC‐2 performs a critical homeostatic role in the subretinal compartment involving a chloride regulatory mechanism that is critical for the survival of both RPE and photoreceptors.
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Affiliation(s)
| | | | - Ignacio Benedicto
- Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Erwin de la Fuente-Ortega
- Departamento de Ciencias Biomédicas, Facultad de Medicina, Universidad Católica del Norte, Coquimbo, Chile
| | - Vadim Y Arshavsky
- Department of Ophthalmology, Duke University School of Medicine, Durham, NC, USA
| | - Ryan Schreiner
- Division of Regenerative Medicine, Ansary Stem Cell Institute, Department of Medicine, Weill Cornell Medicine, New York, NY, USA
| | - Enrique Rodriguez-Boulan
- Department of Ophthalmology, Margaret Dyson Vision Research Institute, Weill Cornell Medicine, New York, NY, USA
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31
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Zhao Q, Kong Y, Kittredge A, Li Y, Shen Y, Zhang Y, Tsang SH, Yang T. Distinct expression requirements and rescue strategies for BEST1 loss- and gain-of-function mutations. eLife 2021; 10:67622. [PMID: 34061021 PMCID: PMC8169119 DOI: 10.7554/elife.67622] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 05/10/2021] [Indexed: 01/23/2023] Open
Abstract
Genetic mutation of the human BEST1 gene, which encodes a Ca2+-activated Cl- channel (BEST1) predominantly expressed in retinal pigment epithelium (RPE), causes a spectrum of retinal degenerative disorders commonly known as bestrophinopathies. Previously, we showed that BEST1 plays an indispensable role in generating Ca2+-dependent Cl- currents in human RPE cells, and the deficiency of BEST1 function in patient-derived RPE is rescuable by gene augmentation (Li et al., 2017). Here, we report that BEST1 patient-derived loss-of-function and gain-of-function mutations require different mutant to wild-type (WT) molecule ratios for phenotypic manifestation, underlying their distinct epigenetic requirements in bestrophinopathy development, and suggesting that some of the previously classified autosomal dominant mutations actually behave in a dominant-negative manner. Importantly, the strong dominant effect of BEST1 gain-of-function mutations prohibits the restoration of BEST1-dependent Cl- currents in RPE cells by gene augmentation, in contrast to the efficient rescue of loss-of-function mutations via the same approach. Moreover, we demonstrate that gain-of-function mutations are rescuable by a combination of gene augmentation with CRISPR/Cas9-mediated knockdown of endogenous BEST1 expression, providing a universal treatment strategy for all bestrophinopathy patients regardless of their mutation types.
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Affiliation(s)
- Qingqing Zhao
- Eye Center, Renmin Hospital of Wuhan University, Wuhan, China.,Department of Pharmacology and Physiology, University of Rochester, School of Medicine and Dentistry, Rochester, United States
| | - Yang Kong
- Department of Ophthalmology, Vagelos College of Physicians & Surgeons, Columbia University, New York, United States
| | - Alec Kittredge
- Department of Pharmacology, Columbia University, New York, United States
| | - Yao Li
- Department of Ophthalmology, Vagelos College of Physicians & Surgeons, Columbia University, New York, United States
| | - Yin Shen
- Eye Center, Medical Research Institute, Renmin Hospital, Wuhan University, Wuhan, China
| | - Yu Zhang
- Department of Ophthalmology, Vagelos College of Physicians & Surgeons, Columbia University, New York, United States
| | - Stephen H Tsang
- Jonas Children's Vision Care, Departments of Ophthalmology and Pathology & Cell Biology, Edward S. Harkness Eye Institute, Institute of Human Nutrition and Columbia Stem Cell Initiative, New York Presbyterian Hospital/Columbia University Irving Medical Center, New York, United States
| | - Tingting Yang
- Department of Pharmacology and Physiology, University of Rochester, School of Medicine and Dentistry, Rochester, United States.,Department of Ophthalmology, Vagelos College of Physicians & Surgeons, Columbia University, New York, United States
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32
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Sorigué D, Hadjidemetriou K, Blangy S, Gotthard G, Bonvalet A, Coquelle N, Samire P, Aleksandrov A, Antonucci L, Benachir A, Boutet S, Byrdin M, Cammarata M, Carbajo S, Cuiné S, Doak RB, Foucar L, Gorel A, Grünbein M, Hartmann E, Hienerwadel R, Hilpert M, Kloos M, Lane TJ, Légeret B, Legrand P, Li-Beisson Y, Moulin SLY, Nurizzo D, Peltier G, Schirò G, Shoeman RL, Sliwa M, Solinas X, Zhuang B, Barends TRM, Colletier JP, Joffre M, Royant A, Berthomieu C, Weik M, Domratcheva T, Brettel K, Vos MH, Schlichting I, Arnoux P, Müller P, Beisson F. Mechanism and dynamics of fatty acid photodecarboxylase. Science 2021; 372:372/6538/eabd5687. [PMID: 33833098 DOI: 10.1126/science.abd5687] [Citation(s) in RCA: 80] [Impact Index Per Article: 26.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 02/17/2021] [Indexed: 12/21/2022]
Abstract
Fatty acid photodecarboxylase (FAP) is a photoenzyme with potential green chemistry applications. By combining static, time-resolved, and cryotrapping spectroscopy and crystallography as well as computation, we characterized Chlorella variabilis FAP reaction intermediates on time scales from subpicoseconds to milliseconds. High-resolution crystal structures from synchrotron and free electron laser x-ray sources highlighted an unusual bent shape of the oxidized flavin chromophore. We demonstrate that decarboxylation occurs directly upon reduction of the excited flavin by the fatty acid substrate. Along with flavin reoxidation by the alkyl radical intermediate, a major fraction of the cleaved carbon dioxide unexpectedly transformed in 100 nanoseconds, most likely into bicarbonate. This reaction is orders of magnitude faster than in solution. Two strictly conserved residues, R451 and C432, are essential for substrate stabilization and functional charge transfer.
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Affiliation(s)
- D Sorigué
- Aix-Marseille University, CEA, CNRS, Institute of Biosciences and Biotechnologies, BIAM Cadarache, 13108 Saint-Paul-lez-Durance, France
| | - K Hadjidemetriou
- Université Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, 38000 Grenoble, France
| | - S Blangy
- Aix-Marseille University, CEA, CNRS, Institute of Biosciences and Biotechnologies, BIAM Cadarache, 13108 Saint-Paul-lez-Durance, France
| | - G Gotthard
- European Synchrotron Radiation Facility, 38043 Grenoble, France
| | - A Bonvalet
- LOB, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France
| | - N Coquelle
- Large-Scale Structures Group, Institut Laue Langevin, 38042 Grenoble Cedex 9, France
| | - P Samire
- Aix-Marseille University, CEA, CNRS, Institute of Biosciences and Biotechnologies, BIAM Cadarache, 13108 Saint-Paul-lez-Durance, France.,Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - A Aleksandrov
- LOB, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France
| | - L Antonucci
- LOB, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France
| | - A Benachir
- LOB, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France
| | - S Boutet
- Linac Coherent Light Source (LCLS), SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - M Byrdin
- Université Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, 38000 Grenoble, France
| | - M Cammarata
- Department of Physics, UMR UR1-CNRS 6251, University of Rennes 1, F-Rennes, France.
| | - S Carbajo
- Linac Coherent Light Source (LCLS), SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - S Cuiné
- Aix-Marseille University, CEA, CNRS, Institute of Biosciences and Biotechnologies, BIAM Cadarache, 13108 Saint-Paul-lez-Durance, France
| | - R B Doak
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - L Foucar
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - A Gorel
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - M Grünbein
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - E Hartmann
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - R Hienerwadel
- Aix-Marseille University, CEA, CNRS, Institute of Biosciences and Biotechnologies, BIAM Cadarache, 13108 Saint-Paul-lez-Durance, France
| | - M Hilpert
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - M Kloos
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany.
| | - T J Lane
- Linac Coherent Light Source (LCLS), SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - B Légeret
- Aix-Marseille University, CEA, CNRS, Institute of Biosciences and Biotechnologies, BIAM Cadarache, 13108 Saint-Paul-lez-Durance, France
| | - P Legrand
- Synchrotron SOLEIL. L'Orme des Merisiers Saint-Aubin, BP 48, 91192 Gif-sur-Yvette, France
| | - Y Li-Beisson
- Aix-Marseille University, CEA, CNRS, Institute of Biosciences and Biotechnologies, BIAM Cadarache, 13108 Saint-Paul-lez-Durance, France
| | - S L Y Moulin
- Aix-Marseille University, CEA, CNRS, Institute of Biosciences and Biotechnologies, BIAM Cadarache, 13108 Saint-Paul-lez-Durance, France
| | - D Nurizzo
- European Synchrotron Radiation Facility, 38043 Grenoble, France
| | - G Peltier
- Aix-Marseille University, CEA, CNRS, Institute of Biosciences and Biotechnologies, BIAM Cadarache, 13108 Saint-Paul-lez-Durance, France
| | - G Schirò
- Université Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, 38000 Grenoble, France
| | - R L Shoeman
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - M Sliwa
- Univ. Lille, CNRS, UMR 8516, LASIRE, LAboratoire de Spectroscopie pour les Interactions, la Réactivité et l'Environnement, 59000 Lille, France
| | - X Solinas
- LOB, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France
| | - B Zhuang
- LOB, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France.,Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - T R M Barends
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany
| | - J-P Colletier
- Université Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, 38000 Grenoble, France
| | - M Joffre
- LOB, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France
| | - A Royant
- Université Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, 38000 Grenoble, France.,European Synchrotron Radiation Facility, 38043 Grenoble, France
| | - C Berthomieu
- Aix-Marseille University, CEA, CNRS, Institute of Biosciences and Biotechnologies, BIAM Cadarache, 13108 Saint-Paul-lez-Durance, France.
| | - M Weik
- Université Grenoble Alpes, CEA, CNRS, Institut de Biologie Structurale, 38000 Grenoble, France.
| | - T Domratcheva
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany. .,Department of Chemistry, Lomonosov Moscow State University, Moscow 119991, Russia
| | - K Brettel
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France
| | - M H Vos
- LOB, CNRS, INSERM, Ecole Polytechnique, Institut Polytechnique de Paris, 91128 Palaiseau, France.
| | - I Schlichting
- Max-Planck-Institut für medizinische Forschung, Jahnstrasse 29, 69120 Heidelberg, Germany.
| | - P Arnoux
- Aix-Marseille University, CEA, CNRS, Institute of Biosciences and Biotechnologies, BIAM Cadarache, 13108 Saint-Paul-lez-Durance, France.
| | - P Müller
- Université Paris-Saclay, CEA, CNRS, Institute for Integrative Biology of the Cell (I2BC), 91198 Gif-sur-Yvette, France.
| | - F Beisson
- Aix-Marseille University, CEA, CNRS, Institute of Biosciences and Biotechnologies, BIAM Cadarache, 13108 Saint-Paul-lez-Durance, France.
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33
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Singh Grewal S, Smith JJ, Carr AJF. Bestrophinopathies: perspectives on clinical disease, Bestrophin-1 function and developing therapies. Ther Adv Ophthalmol 2021; 13:2515841421997191. [PMID: 33738427 PMCID: PMC7934022 DOI: 10.1177/2515841421997191] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 01/27/2021] [Indexed: 12/17/2022] Open
Abstract
Bestrophinopathies are a group of clinically distinct inherited retinal dystrophies that typically affect the macular region, an area synonymous with central high acuity vision. This spectrum of disorders is caused by mutations in bestrophin1 (BEST1), a protein thought to act as a Ca2+-activated Cl- channel in the retinal pigment epithelium (RPE) of the eye. Although bestrophinopathies are rare, over 250 individual pathological mutations have been identified in the BEST1 gene, with many reported to have various clinical expressivity and incomplete penetrance. With no current clinical treatments available for patients with bestrophinopathies, understanding the role of BEST1 in cells and the pathological pathways underlying disease has become a priority. Induced pluripotent stem cell (iPSC) technology is helping to uncover disease mechanisms and develop treatments for RPE diseases, like bestrophinopathies. Here, we provide a comprehensive review of the pathophysiology of bestrophinopathies and highlight how patient-derived iPSC-RPE are being used to test new genomic therapies in vitro.
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Affiliation(s)
| | - Joseph J Smith
- UCL Institute of Ophthalmology, University College London, London, UK
| | - Amanda-Jayne F Carr
- UCL Institute of Ophthalmology, University College London, 11-43 Bath Street, London EC1V 9EL, UK
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34
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van Dijk EHC, Boon CJF. Serous business: Delineating the broad spectrum of diseases with subretinal fluid in the macula. Prog Retin Eye Res 2021; 84:100955. [PMID: 33716160 DOI: 10.1016/j.preteyeres.2021.100955] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 02/14/2021] [Accepted: 02/19/2021] [Indexed: 02/08/2023]
Abstract
A wide range of ocular diseases can present with serous subretinal fluid in the macula and therefore clinically mimic central serous chorioretinopathy (CSC). In this manuscript, we categorise the diseases and conditions that are part of the differential diagnosis into 12 main pathogenic subgroups: neovascular diseases, vitelliform lesions, inflammatory diseases, ocular tumours, haematological malignancies, paraneoplastic syndromes, genetic diseases, ocular developmental anomalies, medication-related conditions and toxicity-related diseases, rhegmatogenous retinal detachment and tractional retinal detachment, retinal vascular diseases, and miscellaneous diseases. In addition, we describe 2 new clinical pictures associated with macular subretinal fluid accumulation, namely serous maculopathy with absence of retinal pigment epithelium (SMARPE) and serous maculopathy due to aspecific choroidopathy (SMACH). Differentiating between these various diseases and CSC can be challenging, and obtaining the correct diagnosis can have immediate therapeutic and prognostic consequences. Here, we describe the key differential diagnostic features of each disease within this clinical spectrum, including representative case examples. Moreover, we discuss the pathogenesis of each disease in order to facilitate the differentiation from typical CSC.
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Affiliation(s)
- Elon H C van Dijk
- Department of Ophthalmology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, the Netherlands
| | - Camiel J F Boon
- Department of Ophthalmology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, the Netherlands; Department of Ophthalmology, Amsterdam University Medical Centers, University of Amsterdam, Meibergdreef 9, 1105 AZ, Amsterdam, the Netherlands.
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35
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Lam AKM, Rheinberger J, Paulino C, Dutzler R. Gating the pore of the calcium-activated chloride channel TMEM16A. Nat Commun 2021; 12:785. [PMID: 33542223 PMCID: PMC7862301 DOI: 10.1038/s41467-020-20787-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 12/16/2020] [Indexed: 02/07/2023] Open
Abstract
The binding of cytoplasmic Ca2+ to the anion-selective channel TMEM16A triggers a conformational change around its binding site that is coupled to the release of a gate at the constricted neck of an hourglass-shaped pore. By combining mutagenesis, electrophysiology, and cryo-electron microscopy, we identified three hydrophobic residues at the intracellular entrance of the neck as constituents of this gate. Mutation of each of these residues increases the potency of Ca2+ and results in pronounced basal activity. The structure of an activating mutant shows a conformational change of an α-helix that contributes to Ca2+ binding as a likely cause for the basal activity. Although not in physical contact, the three residues are functionally coupled to collectively contribute to the stabilization of the gate in the closed conformation of the pore, thus explaining the low open probability of the channel in the absence of Ca2+.
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Affiliation(s)
- Andy K M Lam
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland.
| | - Jan Rheinberger
- Department of Structural Biology and Membrane Enzymology at the Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747, AG, Groningen, The Netherlands
| | - Cristina Paulino
- Department of Structural Biology and Membrane Enzymology at the Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747, AG, Groningen, The Netherlands.
| | - Raimund Dutzler
- Department of Biochemistry, University of Zurich, Winterthurerstrasse 190, CH-8057, Zurich, Switzerland.
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36
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Deng Z, Zhao Y, Feng J, Zhang J, Zhao H, Rau MJ, Fitzpatrick JAJ, Hu H, Yuan P. Cryo-EM structure of a proton-activated chloride channel TMEM206. SCIENCE ADVANCES 2021; 7:7/9/eabe5983. [PMID: 33627432 PMCID: PMC7904269 DOI: 10.1126/sciadv.abe5983] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 01/08/2021] [Indexed: 05/12/2023]
Abstract
TMEM206 has been recently identified as an evolutionarily conserved chloride channel that underlies ubiquitously expressed, proton-activated, outwardly rectifying anion currents. Here, we report the cryo-electron microscopy structure of pufferfish TMEM206, which forms a trimeric channel, with each subunit comprising two transmembrane segments and a large extracellular domain. An ample vestibule in the extracellular region is accessible laterally from the three side portals. The central pore contains multiple constrictions. A conserved lysine residue near the cytoplasmic end of the inner helix forms the presumed chloride ion selectivity filter. Unprecedentedly, the core structure and assembly closely resemble those of the epithelial sodium channel/degenerin family of sodium channels that are unrelated in amino acid sequence and conduct cations instead of anions. Together with electrophysiology, this work provides insights into ion conduction and gating for a new class of chloride channels that is architecturally distinct from previously characterized chloride channel families.
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Affiliation(s)
- Zengqin Deng
- Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, MO 63110, USA
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Yonghui Zhao
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO 63110, USA
- Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Jing Feng
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO 63110, USA
- Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Jingying Zhang
- Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, MO 63110, USA
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Haiyan Zhao
- Department of Pathology and Immunology, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Michael J Rau
- Washington University Center for Cellular Imaging, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - James A J Fitzpatrick
- Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, MO 63110, USA
- Washington University Center for Cellular Imaging, Washington University School of Medicine, Saint Louis, MO 63110, USA
- Department of Neuroscience, Washington University School of Medicine, Saint Louis, MO 63110, USA
- Department of Biomedical Engineering, Washington University in Saint Louis, Saint Louis, MO 63130, USA
| | - Hongzhen Hu
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO 63110, USA
- Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, Saint Louis, MO 63110, USA
| | - Peng Yuan
- Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, MO 63110, USA.
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO 63110, USA
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37
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Ravichandran G, Raju SV, Sarkar P, N. T. S, Al Olayan EM, Aloufi AS, Elokaby MA, Arshad A, Mala K, Arockiaraj J. Bestrophin‐derived peptide,
WP17
, elicits cell wall disruption‐mediated bactericidal activity against
Micrococcus luteus
and anti‐neoplastic effect against murine melanoma cells. Pept Sci (Hoboken) 2021. [DOI: 10.1002/pep2.24220] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Gayathri Ravichandran
- SRM Research Institute, SRM Institute of Science and Technology Chennai Tamil Nadu India
| | - Stefi V. Raju
- SRM Research Institute, SRM Institute of Science and Technology Chennai Tamil Nadu India
| | - Purabi Sarkar
- SRM Research Institute, SRM Institute of Science and Technology Chennai Tamil Nadu India
| | - Saraswathi N. T.
- Molecular Biophysics Lab School of Chemical and Biotechnology, SASTRA Deemed to be University Thanjavur Tamil Nadu India
| | - Ebtesam M. Al Olayan
- Department of Zoology College of Science, King Saud University Riyadh Saudi Arabia
| | - Abeer S. Aloufi
- Department of Zoology College of Science, King Saud University Riyadh Saudi Arabia
| | - Mohamed A. Elokaby
- Aquaculture Division National Institute of Oceanography and Fisheries (NIOF) Alexandria Egypt
| | - Aziz Arshad
- International Institute of Aquaculture and Aquatic Sciences (I‐AQUAS) Universiti Putra Malaysia Port Dickson Negeri Sembilan Malaysia
- Department of Aquaculture, Faculty of Agriculture University Putra Malaysia Serdang Selangor Malaysia
| | - Kanchana Mala
- Department of Medical Research Medical College Hospital & Research Centre, SRM Institute of Science & Technology Chennai Tamil Nadu India
| | - Jesu Arockiaraj
- SRM Research Institute, SRM Institute of Science and Technology Chennai Tamil Nadu India
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38
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Linsdell P. On the relationship between anion binding and chloride conductance in the CFTR anion channel. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2021; 1863:183558. [PMID: 33444622 DOI: 10.1016/j.bbamem.2021.183558] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 12/21/2020] [Accepted: 12/29/2020] [Indexed: 12/26/2022]
Abstract
Mutations at many sites within the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel pore region result in changes in chloride conductance. Although chloride binding in the pore - as well as interactions between concurrently bound chloride ions - are thought to be important facets of the chloride permeation mechanism, little is known about the relationship between anion binding and chloride conductance. The present work presents a comprehensive investigation of a number of anion binding properties in different pore mutants with differential effects on chloride conductance. When multiple pore mutants are compared, conductance appears best correlated with the ability of anions to bind to the pore when it is already occupied by chloride ions. In contrast, conductance was not correlated with biophysical measures of anion:anion interactions inside the pore. Although these findings suggest anion binding is required for high conductance, mutations that strengthened anion binding had very little effect on conductance, especially at high chloride concentrations, suggesting that the wild-type CFTR pore is already close to saturated with chloride ions. These results are used to support a revised model of chloride permeation in CFTR in which the overall chloride occupancy of multiple loosely-defined chloride binding sites results in high chloride conductance through the pore.
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Affiliation(s)
- Paul Linsdell
- Department of Physiology & Biophysics, Dalhousie University, Halifax, Nova Scotia, Canada.
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39
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Kerth CM, Hautvast P, Körner J, Lampert A, Meents JE. Phosphorylation of a chronic pain mutation in the voltage-gated sodium channel Nav1.7 increases voltage sensitivity. J Biol Chem 2021; 296:100227. [PMID: 33361158 PMCID: PMC7948457 DOI: 10.1074/jbc.ra120.014288] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 12/17/2020] [Accepted: 12/22/2020] [Indexed: 12/19/2022] Open
Abstract
Mutations in voltage-gated sodium channels (Navs) can cause alterations in pain sensation, such as chronic pain diseases like inherited erythromelalgia. The mutation causing inherited erythromelalgia, Nav1.7 p.I848T, is known to induce a hyperpolarized shift in the voltage dependence of activation in Nav1.7. So far, however, the mechanism to explain this increase in voltage sensitivity remains unknown. In the present study, we show that phosphorylation of the newly introduced Thr residue explains the functional change. We expressed wildtype human Nav1.7, the I848T mutant, or other mutations in HEK293T cells and performed whole-cell patch-clamp electrophysiology. As the insertion of a Thr residue potentially creates a novel phosphorylation site for Ser/Thr kinases and because Nav1.7 had been shown in Xenopus oocytes to be affected by protein kinases C and A, we used different nonselective and selective kinase inhibitors and activators to test the effect of phosphorylation on Nav1.7 in a human system. We identify protein kinase C, but not protein kinase A, to be responsible for the phosphorylation of T848 and thereby for the shift in voltage sensitivity. Introducing a negatively charged amino acid instead of the putative phosphorylation site mimics the effect on voltage gating to a lesser extent. 3D modeling using the published cryo-EM structure of human Nav1.7 showed that introduction of this negatively charged site seems to alter the interaction of this residue with the surrounding amino acids and thus to influence channel function. These results could provide new opportunities for the development of novel treatment options for patients with chronic pain.
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Affiliation(s)
- Clara M Kerth
- Institute of Physiology, Uniklinik RWTH Aachen University, Aachen, Germany
| | - Petra Hautvast
- Institute of Physiology, Uniklinik RWTH Aachen University, Aachen, Germany
| | - Jannis Körner
- Institute of Physiology, Uniklinik RWTH Aachen University, Aachen, Germany; Department of Anesthesiology, Uniklinik RWTH Aachen University, Aachen, Germany
| | - Angelika Lampert
- Institute of Physiology, Uniklinik RWTH Aachen University, Aachen, Germany
| | - Jannis E Meents
- Institute of Physiology, Uniklinik RWTH Aachen University, Aachen, Germany.
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40
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Fernandez-Abascal J, Graziano B, Encalada N, Bianchi L. Glial Chloride Channels in the Function of the Nervous System Across Species. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2021; 1349:195-223. [PMID: 35138616 DOI: 10.1007/978-981-16-4254-8_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
In the nervous system, the concentration of Cl- in neurons that express GABA receptors plays a key role in establishing whether these neurons are excitatory, mostly during early development, or inhibitory. Thus, much attention has been dedicated to understanding how neurons regulate their intracellular Cl- concentration. However, regulation of the extracellular Cl- concentration by other cells of the nervous system, including glia and microglia, is as important because it ultimately affects the Cl- equilibrium potential across the neuronal plasma membrane. Moreover, Cl- ions are transported in and out of the cell, via either passive or active transporter systems, as counter ions for K+ whose concentration in the extracellular environment of the nervous system is tightly regulated because it directly affects neuronal excitability. In this book chapter, we report on the Cl- channel types expressed in the various types of glial cells focusing on the role they play in the function of the nervous system in health and disease. Furthermore, we describe the types of stimuli that these channels are activated by, the other solutes that they may transport, and the involvement of these channels in processes such as pH regulation and Regulatory Volume Decrease (RVD). The picture that emerges is one of the glial cells expressing a variety of Cl- channels, encoded by members of different gene families, involved both in short- and long-term regulation of the nervous system function. Finally, we report data on invertebrate model organisms, such as C. elegans and Drosophila, that are revealing important and previously unsuspected functions of some of these channels in the context of living and behaving animals.
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Affiliation(s)
- Jesus Fernandez-Abascal
- Department Physiology and Biophysics, University of Miami, Miller School of Medicine, Miami, FL, USA
| | - Bianca Graziano
- Department Physiology and Biophysics, University of Miami, Miller School of Medicine, Miami, FL, USA
| | - Nicole Encalada
- Department Physiology and Biophysics, University of Miami, Miller School of Medicine, Miami, FL, USA
| | - Laura Bianchi
- Department Physiology and Biophysics, University of Miami, Miller School of Medicine, Miami, FL, USA.
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41
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Kermani AA. A guide to membrane protein X‐ray crystallography. FEBS J 2020; 288:5788-5804. [DOI: 10.1111/febs.15676] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 11/17/2020] [Accepted: 12/14/2020] [Indexed: 12/18/2022]
Affiliation(s)
- Ali A. Kermani
- Department of Molecular, Cellular, and Developmental Biology University of Michigan Ann Arbor MI USA
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42
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Mandala VS, McKay MJ, Shcherbakov AA, Dregni AJ, Kolocouris A, Hong M. Structure and drug binding of the SARS-CoV-2 envelope protein transmembrane domain in lipid bilayers. Nat Struct Mol Biol 2020; 27:1202-1208. [PMID: 33177698 PMCID: PMC7718435 DOI: 10.1038/s41594-020-00536-8] [Citation(s) in RCA: 240] [Impact Index Per Article: 60.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 10/28/2020] [Indexed: 12/19/2022]
Abstract
An essential protein of the SARS-CoV-2 virus, the envelope protein E, forms a homopentameric cation channel that is important for virus pathogenicity. Here we report a 2.1-Å structure and the drug-binding site of E's transmembrane domain (ETM), determined using solid-state NMR spectroscopy. In lipid bilayers that mimic the endoplasmic reticulum-Golgi intermediate compartment (ERGIC) membrane, ETM forms a five-helix bundle surrounding a narrow pore. The protein deviates from the ideal α-helical geometry due to three phenylalanine residues, which stack within each helix and between helices. Together with valine and leucine interdigitation, these cause a dehydrated pore compared with the viroporins of influenza viruses and HIV. Hexamethylene amiloride binds the polar amino-terminal lumen, whereas acidic pH affects the carboxy-terminal conformation. Thus, the N- and C-terminal halves of this bipartite channel may interact with other viral and host proteins semi-independently. The structure sets the stage for designing E inhibitors as antiviral drugs.
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Affiliation(s)
- Venkata S Mandala
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Matthew J McKay
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | - Aurelio J Dregni
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Antonios Kolocouris
- Department of Pharmaceutical Chemistry, National and Kapodistrian University of Athens, Panepistimioupolis Zografou, Athens, Greece
| | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA, USA.
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43
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Bonilha VL, Bell BA, DeBenedictis MJ, Hagstrom SA, Fishman GA, Hollyfield JG. Cellular Changes in Retinas From Patients With BEST1 Mutations. Front Cell Dev Biol 2020; 8:573330. [PMID: 33154968 PMCID: PMC7591587 DOI: 10.3389/fcell.2020.573330] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 09/03/2020] [Indexed: 11/24/2022] Open
Abstract
Best disease (BD), also known as vitelliform macular dystrophy, is an inherited disease of the central retina caused by more than 300 pathogenic variants in the BEST1 gene. The phenotype of BD is variable, and there are just a few reports on the histopathology of eyes from donors with BD. Here, we describe the histopathological comparison of donor’s eyes from two patients with BD. Eyes obtained from 85-year-old (donor 1) and 65-year-old (donor 2) donors were fixed within 25 h postmortem. Perifoveal and peripheral retinal regions were processed for histology and immunocytochemistry using retinal-specific and retinal pigment epithelium (RPE)-specific antibodies. Three age-matched normal eyes were used as controls. DNA was obtained from donor blood samples. Sequence analysis of the entire BEST1 coding region was performed and identified a c.886A > C (p.Asn296His) variant in donor 1 and a c.602T > C (p.Ile201Thr) variant in donor 2; both mutations were heterozygous. Fundus examination showed that donor 1 displayed a macular lesion with considerable scarring while donor 2 displayed close to normal macular morphology. Our studies of histology and molecular pathology in the perifovea and periphery of these two BD donor eyes revealed panretinal abnormalities in both photoreceptors and RPE cellular levels in the periphery; donor 1 also displayed macular lesion. Our findings confirm the phenotypic variability of BD associated with BEST1 variants.
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Affiliation(s)
- Vera L Bonilha
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States.,Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH, United States
| | - Brent A Bell
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States.,Scheie Eye Institute, University of Pennsylvania, Philadelphia, PA, United States
| | - Meghan J DeBenedictis
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States
| | - Stephanie A Hagstrom
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States.,Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH, United States
| | - Gerald A Fishman
- Pangere Center at The Chicago Lighthouse for People Who Are Blind or Visually Impaired, Chicago, IL, United States
| | - Joe G Hollyfield
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, United States.,Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, OH, United States
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44
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Casalino G, Khan KN, Armengol M, Wright G, Pontikos N, Georgiou M, Webster AR, Robson AG, Grewal PS, Michaelides M. Autosomal Recessive Bestrophinopathy: Clinical Features, Natural History, and Genetic Findings in Preparation for Clinical Trials. Ophthalmology 2020; 128:706-718. [PMID: 33039401 PMCID: PMC8062850 DOI: 10.1016/j.ophtha.2020.10.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 09/11/2020] [Accepted: 10/02/2020] [Indexed: 12/26/2022] Open
Abstract
Purpose To investigate the clinical course, genetic findings, and phenotypic spectrum of autosomal recessive bestrophinopathy (ARB) in a large cohort of children and adults. Design Retrospective case series. Participants Patients with a detailed clinical phenotype consistent with ARB, biallelic likely disease-causing sequence variants in the BEST1 gene, or both identified at a single tertiary referral center. Methods Review of case notes, retinal imaging (color fundus photography, fundus autofluorescence, OCT), electrophysiologic assessment, and molecular genetic testing. Main Outcome Measures Visual acuity (VA), retinal imaging, and electrophysiologic changes over time. Results Fifty-six eyes of 28 unrelated patients were included. Compound heterozygous variants were detected in most patients (19/27), with 6 alleles recurring in apparently unrelated individuals, the most common of which was c.422G→A, p.(Arg141His; n = 4 patients). Mean presenting VA was 0.52 ± 0.36 logarithm of the minimum angle of resolution (logMAR), and final VA was 0.81 ± 0.75 logMAR (P = 0.06). The mean rate of change in VA was 0.05 ± 0.13 logMAR/year. A significant change in VA was detected in patients with a follow-up of 5 years or more (n = 18) compared with patients with a follow-up of 5 years or less (n = 10; P = 0.001). Presence of subretinal fluid and vitelliform material were early findings in most patients, and this did not change substantially over time. A reduction in central retinal thickness was detected in most eyes (80.4%) over the course of follow-up. Many patients (10/26) showed evidence of generalized rod and cone system dysfunction. These patients were older (P < 0.001) and had worse VA (P = 0.02) than those with normal full-field electroretinography results. Conclusions Although patients with ARB are presumed to have no functioning bestrophin channels, significant phenotypic heterogeneity is evident. The clinical course is characterized by a progressive loss of vision with a slow rate of decline, providing a wide therapeutic window for anticipated future treatment strategies.
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Affiliation(s)
- Giuseppe Casalino
- Moorfields Eye Hospital NHS Foundation Trust, and UCL Institute of Ophthalmology, University College London, London, United Kingdom; Oftalmico Hospital, ASST Fatebenefratelli Sacco, Milan, Italy
| | - Kamron N Khan
- Leeds Teaching Hospitals NHS Trust, Leeds, United Kingdom
| | - Monica Armengol
- Guy's and St. Thomas' Hospital NHS Foundation Trust, London, United Kingdom
| | - Genevieve Wright
- Moorfields Eye Hospital NHS Foundation Trust, and UCL Institute of Ophthalmology, University College London, London, United Kingdom
| | - Nikolas Pontikos
- Moorfields Eye Hospital NHS Foundation Trust, and UCL Institute of Ophthalmology, University College London, London, United Kingdom
| | - Michalis Georgiou
- Moorfields Eye Hospital NHS Foundation Trust, and UCL Institute of Ophthalmology, University College London, London, United Kingdom
| | - Andrew R Webster
- Moorfields Eye Hospital NHS Foundation Trust, and UCL Institute of Ophthalmology, University College London, London, United Kingdom
| | - Anthony G Robson
- Moorfields Eye Hospital NHS Foundation Trust, and UCL Institute of Ophthalmology, University College London, London, United Kingdom
| | - Parampal S Grewal
- Moorfields Eye Hospital NHS Foundation Trust, and UCL Institute of Ophthalmology, University College London, London, United Kingdom
| | - Michel Michaelides
- Moorfields Eye Hospital NHS Foundation Trust, and UCL Institute of Ophthalmology, University College London, London, United Kingdom.
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Liu J, Taylor RL, Baines RA, Swanton L, Freeman S, Corneo B, Patel A, Marmorstein A, Knudsen T, Black GC, Manson F. Small Molecules Restore Bestrophin 1 Expression and Function of Both Dominant and Recessive Bestrophinopathies in Patient-Derived Retinal Pigment Epithelium. Invest Ophthalmol Vis Sci 2020; 61:28. [PMID: 32421148 PMCID: PMC7405785 DOI: 10.1167/iovs.61.5.28] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Purpose Bestrophinopathies are a group of untreatable inherited retinal dystrophies caused by mutations in the retinal pigment epithelium (RPE) Cl− channel bestrophin 1. We tested whether sodium phenylbutyrate (4PBA) could rescue the function of mutant bestrophin 1 associated with autosomal dominant and recessive disease. We then sought analogues of 4PBA with increased potency and determined the mode of action for 4PBA and a lead compound 2-naphthoxyacetic acid (2-NOAA). Lastly, we tested if 4PBA and 2-NOAA could functionally rescue bestrophin 1 function in RPE generated from induced pluripotent stem cells (iPSC-RPEs) derived from patients with a dominant or recessive bestrophinopathy. Methods Global and plasma membrane expression was determined by Western blot and immunofluorescent microscopy, respectively. The effect of 4PBA and 2-NOAA on transcription was measured by quantitative RT-PCR and the rate of protein turnover by cycloheximide chase and Western blot. Channel function was measured by whole-cell patch clamp. Results 4PBA and 2-NOAA can rescue the global and membrane expression of mutant bestrophin 1 associated with autosomal dominant disease (Best vitelliform macular dystrophy [BVMD]) and autosome recessive bestrophinopathy (ARB), and these small molecules have different modes of action. Both 4PBA and 2-NOAA significantly increased the channel function of mutant BVMD and ARB bestrophin 1 in HEK293T and iPSC-RPE cells derived from patients with BVMD and ARB. For 4PBA, the increased mutant channel function in BVMD and ARB iPSC-RPE was equal to that of wild-type iPSC-RPE bestrophin 1. Conclusions The restoration of bestrophin 1 function in patient-derived RPE confirms the US Food and Drug Administration–approved drug 4PBA as a promising therapeutic treatment for bestrophinopathies.
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Mandala VS, McKay MJ, Shcherbakov AA, Dregni AJ, Kolocouris A, Hong M. Structure and Drug Binding of the SARS-CoV-2 Envelope Protein in Phospholipid Bilayers. RESEARCH SQUARE 2020:rs.3.rs-77124. [PMID: 32995764 PMCID: PMC7523133 DOI: 10.21203/rs.3.rs-77124/v1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the ongoing COVID-19 pandemic. Successful development of vaccines and antivirals against SARS-CoV-2 requires a comprehensive understanding of the essential proteins of the virus. The envelope (E) protein of SARS-CoV-2 assembles into a cation-selective channel that mediates virus budding, release, and host inflammation response. E blockage reduces virus pathogenicity while E deletion attenuates the virus. Here we report the 2.4 Å structure and drug-binding site of E's transmembrane (TM) domain, determined using solid-state nuclear magnetic resonance (NMR) spectroscopy. In lipid bilayers that mimic the endoplasmic reticulum Golgi intermediate compartment (ERGIC) membrane, ETM forms a five-helix bundle surrounding a narrow central pore. The middle of the TM segment is distorted from the ideal a-helical geometry due to three regularly spaced phenylalanine residues, which stack within each helix and between neighboring helices. These aromatic interactions, together with interhelical Val and Leu interdigitation, cause a dehydrated pore compared to the viroporins of influenza and HIV viruses. Hexamethylene amiloride and amantadine bind shallowly to polar residues at the N-terminal lumen, while acidic pH affects the C-terminal conformation. These results indicate that SARS-CoV-2 E forms a structurally robust but bipartite channel whose N- and C-terminal halves can interact with drugs, ions and other viral and host proteins semi-independently. This structure establishes the atomic basis for designing E inhibitors as antiviral drugs against SARS-CoV-2.
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Affiliation(s)
- Venkata S. Mandala
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - Matthew J. McKay
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - Alexander A. Shcherbakov
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - Aurelio J. Dregni
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
| | - Antonios Kolocouris
- Department of Pharmaceutical Chemistry, National and Kapodistrian University of Athens, Panepistimioupolis Zografou, Athens 15771, Greece
| | - Mei Hong
- Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, 02139, USA
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Sensing through Non-Sensing Ocular Ion Channels. Int J Mol Sci 2020; 21:ijms21186925. [PMID: 32967234 PMCID: PMC7554890 DOI: 10.3390/ijms21186925] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 09/17/2020] [Accepted: 09/18/2020] [Indexed: 12/12/2022] Open
Abstract
Ion channels are membrane-spanning integral proteins expressed in multiple organs, including the eye. In the eye, ion channels are involved in various physiological processes, like signal transmission and visual processing. A wide range of mutations have been reported in the corresponding genes and their interacting subunit coding genes, which contribute significantly to an array of blindness, termed ocular channelopathies. These mutations result in either a loss- or gain-of channel functions affecting the structure, assembly, trafficking, and localization of channel proteins. A dominant-negative effect is caused in a few channels formed by the assembly of several subunits that exist as homo- or heteromeric proteins. Here, we review the role of different mutations in switching a “sensing” ion channel to “non-sensing,” leading to ocular channelopathies like Leber’s congenital amaurosis 16 (LCA16), cone dystrophy, congenital stationary night blindness (CSNB), achromatopsia, bestrophinopathies, retinitis pigmentosa, etc. We also discuss the various in vitro and in vivo disease models available to investigate the impact of mutations on channel properties, to dissect the disease mechanism, and understand the pathophysiology. Innovating the potential pharmacological and therapeutic approaches and their efficient delivery to the eye for reversing a “non-sensing” channel to “sensing” would be life-changing.
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48
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Sinha D, Steyer B, Shahi PK, Mueller KP, Valiauga R, Edwards KL, Bacig C, Steltzer SS, Srinivasan S, Abdeen A, Cory E, Periyasamy V, Siahpirani AF, Stone EM, Tucker BA, Roy S, Pattnaik BR, Saha K, Gamm DM. Human iPSC Modeling Reveals Mutation-Specific Responses to Gene Therapy in a Genotypically Diverse Dominant Maculopathy. Am J Hum Genet 2020; 107:278-292. [PMID: 32707085 DOI: 10.1016/j.ajhg.2020.06.011] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 06/12/2020] [Indexed: 12/26/2022] Open
Abstract
Dominantly inherited disorders are not typically considered to be therapeutic candidates for gene augmentation. Here, we utilized induced pluripotent stem cell-derived retinal pigment epithelium (iPSC-RPE) to test the potential of gene augmentation to treat Best disease, a dominant macular dystrophy caused by over 200 missense mutations in BEST1. Gene augmentation in iPSC-RPE fully restored BEST1 calcium-activated chloride channel activity and improved rhodopsin degradation in an iPSC-RPE model of recessive bestrophinopathy as well as in two models of dominant Best disease caused by different mutations in regions encoding ion-binding domains. A third dominant Best disease iPSC-RPE model did not respond to gene augmentation, but showed normalization of BEST1 channel activity following CRISPR-Cas9 editing of the mutant allele. We then subjected all three dominant Best disease iPSC-RPE models to gene editing, which produced premature stop codons specifically within the mutant BEST1 alleles. Single-cell profiling demonstrated no adverse perturbation of retinal pigment epithelium (RPE) transcriptional programs in any model, although off-target analysis detected a silent genomic alteration in one model. These results suggest that gene augmentation is a viable first-line approach for some individuals with dominant Best disease and that non-responders are candidates for alternate approaches such as gene editing. However, testing gene editing strategies for on-target efficiency and off-target events using personalized iPSC-RPE model systems is warranted. In summary, personalized iPSC-RPE models can be used to select among a growing list of gene therapy options to maximize safety and efficacy while minimizing time and cost. Similar scenarios likely exist for other genotypically diverse channelopathies, expanding the therapeutic landscape for affected individuals.
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Affiliation(s)
- Divya Sinha
- McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI 53705, USA; Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Benjamin Steyer
- McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI 53705, USA; Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, WI 53715, USA
| | - Pawan K Shahi
- McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI 53705, USA; Department of Pediatrics, University of Wisconsin-Madison, Madison, WI 53792, USA
| | - Katherine P Mueller
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, WI 53715, USA
| | - Rasa Valiauga
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA
| | | | - Cole Bacig
- Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Stephanie S Steltzer
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, WI 53715, USA
| | - Sandhya Srinivasan
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, WI 53715, USA
| | - Amr Abdeen
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, WI 53715, USA
| | - Evan Cory
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, WI 53715, USA
| | - Viswesh Periyasamy
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, WI 53715, USA
| | | | - Edwin M Stone
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Budd A Tucker
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Sushmita Roy
- Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, WI 53715, USA; Department of Biostatistics, University of Wisconsin-Madison, Madison, WI 53792, USA
| | - Bikash R Pattnaik
- McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI 53705, USA; Department of Pediatrics, University of Wisconsin-Madison, Madison, WI 53792, USA; Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI 53705, USA
| | - Krishanu Saha
- McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI 53705, USA; Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, WI 53715, USA; Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA.
| | - David M Gamm
- McPherson Eye Research Institute, University of Wisconsin-Madison, Madison, WI 53705, USA; Waisman Center, University of Wisconsin-Madison, Madison, WI 53705, USA; Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, WI 53705, USA.
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Bae HE, Cecchetti C, Du Y, Katsube S, Mortensen JS, Huang W, Rehan S, Lee HJ, Loland CJ, Guan L, Kobilka BK, Byrne B, Chae PS. Pendant-bearing glucose-neopentyl glycol (P-GNG) amphiphiles for membrane protein manipulation: Importance of detergent pendant chain for protein stabilization. Acta Biomater 2020; 112:250-261. [PMID: 32522715 DOI: 10.1016/j.actbio.2020.06.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Revised: 05/31/2020] [Accepted: 06/02/2020] [Indexed: 12/15/2022]
Abstract
Glucoside detergents are successfully used for membrane protein crystallization mainly because of their ability to form small protein-detergent complexes. In a previous study, we introduced glucose neopentyl glycol (GNG) amphiphiles with a branched diglucoside structure that has facilitated high resolution crystallographic structure determination of several membrane proteins. Like other glucoside detergents, however, these GNGs were less successful than DDM in stabilizing membrane proteins, limiting their wide use in protein structural study. As a strategy to improve GNG efficacy for protein stabilization, we introduced two different alkyl chains (i.e., main and pendant chains) into the GNG scaffold while maintaining the branched diglucoside head group. Of these pendant-bearing GNGs (P-GNGs), three detergents (GNG-2,14, GNG-3,13 and GNG-3,14) were not only notably better than both DDM (a gold standard detergent) and the previously described GNGs at stabilizing all six membrane proteins tested here, but were also as efficient as DDM at membrane protein extraction. The results suggest that the C14 main chain of the P-GNGs is highly compatible with the hydrophobic widths of membrane proteins, while the C2/C3 pendant chain is effective at strengthening detergent hydrophobic interactions. Based on the marked effect on protein stability and solubility, these glucoside detergents hold significant potential for membrane protein structural study. Furthermore, the independent roles of the detergent two alkyl chains first introduced in this study have shed light on new amphiphile design for membrane protein study. STATEMENT OF SIGNIFICANCE: Detergent efficacy for protein stabilization tends to be protein-specific, thus it is challenging to find a detergent that is effective at stabilizing multiple membrane proteins. By incorporating a pendant chain into our previous GNG scaffold, we prepared pendant chain-bearing GNGs (P-GNGs) and identified three P-GNGs that were highly effective at stabilizing all membrane proteins tested here including two GPCRs. In addition, the new detergents were as efficient as DDM at extracting membrane proteins, enabling use of these detergents over the multiple steps of protein isolation. The key difference between the P-GNGs and other glucoside detergents, the presence of a pendant chain, is likely to be responsible for their markedly enhanced protein stabilization behavior.
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Affiliation(s)
- Hyoung Eun Bae
- Department of Bionanotechnology, Hanyang University, Ansan, 15588 (Korea)
| | - Cristina Cecchetti
- Department of Life Sciences, Imperial College London, London, SW7 2AZ (UK)
| | - Yang Du
- Department of Molecular and Cellular Physiology, Stanford University, CA 94305 (USA)
| | - Satoshi Katsube
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430 (USA)
| | - Jonas S Mortensen
- Department of Neuroscience, University of Copenhagen, Copenhagen, DK-2200 (Denmark)
| | - Weijiao Huang
- Department of Molecular and Cellular Physiology, Stanford University, CA 94305 (USA)
| | - Shahid Rehan
- Institute of Biotechnology, University of Helsinki, Helsinki (Finland); HiLIFE, University of Helsinki, Helsinki (Finland)
| | - Ho Jin Lee
- Department of Bionanotechnology, Hanyang University, Ansan, 15588 (Korea)
| | - Claus J Loland
- Department of Neuroscience, University of Copenhagen, Copenhagen, DK-2200 (Denmark)
| | - Lan Guan
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, School of Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430 (USA)
| | - Brian K Kobilka
- Department of Molecular and Cellular Physiology, Stanford University, CA 94305 (USA)
| | - Bernadette Byrne
- Department of Life Sciences, Imperial College London, London, SW7 2AZ (UK)
| | - Pil Seok Chae
- Department of Bionanotechnology, Hanyang University, Ansan, 15588 (Korea).
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50
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Ormel L, Lauritzen KH, Schreiber R, Kunzelmann K, Gundersen V. GABA, but Not Bestrophin-1, Is Localized in Astroglial Processes in the Mouse Hippocampus and the Cerebellum. Front Mol Neurosci 2020; 13:135. [PMID: 32848599 PMCID: PMC7399226 DOI: 10.3389/fnmol.2020.00135] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 07/07/2020] [Indexed: 11/13/2022] Open
Abstract
GABA is proposed to act as a gliotransmitter in the brain. Differences in GABA release from astroglia are thought to underlie differences in tonic inhibition between the cerebellum and the CA1 hippocampus. Here we used quantitative immunogold cytochemistry to localize and compare the levels of GABA in astroglia in these brain regions. We found that the density of GABA immunogold particles was similar in delicate processes of Bergman glia in the cerebellum and astrocytes in the CA1 hippocampus. The astrocytic GABA release is proposed to be mediated by, among others, the Ca2+ activated Cl- channel bestrophin-1. The bestrophin-1 antibodies did not show any significant bestrophin-1 signal in the brain of wt mice, nor in bestrophin-1 knockout mice. The bestrophin-1 signal was low both on Western blots and immunofluorescence laser scanning microscopic images. These results suggest that GABA is localized in astroglia, but in similar concentrations in the cerebellum and CA1 hippocampus, and thus cannot account for differences in tonic inhibition between these brain regions. Furthermore, our data seem to suggest that the GABA release from astroglia previously observed in the hippocampus and cerebellum occurs via mechanisms other than bestrophin-1.
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Affiliation(s)
- Lasse Ormel
- Section of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.,Department of Neurology, Oslo University Hospital, Ullevål, Oslo, Norway
| | - Knut H Lauritzen
- Section of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.,Research Institute of Internal Medicine, Oslo University Hospital, Rikshospitalet, Oslo, Norway
| | - Rainer Schreiber
- Department of Physiology, University of Regensburg, Regensburg, Germany
| | - Karl Kunzelmann
- Department of Physiology, University of Regensburg, Regensburg, Germany
| | - Vidar Gundersen
- Section of Anatomy, Department of Molecular Medicine, Institute of Basic Medical Sciences, University of Oslo, Oslo, Norway.,Section for Movement Disorders, Department of Neurology, Oslo University Hospital, Rikshospitalet, Oslo, Norway
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