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Avalos-Hernandez A, Juarez-Navarro K, Ruiz-Baca E, Meneses-Morales I, Espino-Saldaña E, Martinez-Torres A, Lopez-Rodriguez A. Unlocking cellular traffic jams: olive oil-mediated rescue of CNG mutant channels. Front Pharmacol 2024; 15:1408156. [PMID: 39119605 PMCID: PMC11306028 DOI: 10.3389/fphar.2024.1408156] [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: 03/27/2024] [Accepted: 06/28/2024] [Indexed: 08/10/2024] Open
Abstract
One of the reasons to suggest olive oil consumption for a healthy life is its potential to induce robust lipidomic remodeling through membrane modification by dietary lipids. This remodeling might, in turn, modulate essential lipid-protein interactions while maintaining accurate transmembrane protein/domain orientation. Oleic acid, the primary compound in olive oil, has been suggested as a modulator of ion channel function. In this study, we explored whether this lipid could rescue the trafficking of mutated transmembrane proteins. In our initial approach, we supplemented the cell culture medium of HEK-293 cells expressing cyclic nucleotide channels tagged using green fluorescent protein (CNG-GFP) with olive oil or oleic acid. In addition to wild-type channels, we also expressed R272Q and R278W mutant channels, two non-functional intracellularly retained channels related to retinopathies. We used fluorescence microscopy and patch-clamp in the inside-out configuration to assess changes in the cell localization and function of the tested channels. Our results demonstrated that olive oil and oleic acid facilitated the transport of cyclic nucleotide-gated R272Q mutant channels towards the plasma membrane, rendering them electrophysiologically functional. Thus, our findings reveal a novel property of olive oil as a membrane protein traffic inductor.
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Affiliation(s)
| | - Karina Juarez-Navarro
- Facultad de Ciencias Químicas, Universidad Juárez del Estado de Durango, Durango, Mexico
| | - Estela Ruiz-Baca
- Facultad de Ciencias Químicas, Universidad Juárez del Estado de Durango, Durango, Mexico
| | - Ivan Meneses-Morales
- Facultad de Ciencias Químicas, Universidad Juárez del Estado de Durango, Durango, Mexico
| | - Edith Espino-Saldaña
- Laboratorio de Neurobiología Molecular y Celular, Instituto de Neurobiología, Universidad Nacional Autónoma de México. Campus Juriquilla, Juriquilla, Mexico
| | - Ataulfo Martinez-Torres
- Laboratorio de Neurobiología Molecular y Celular, Instituto de Neurobiología, Universidad Nacional Autónoma de México. Campus Juriquilla, Juriquilla, Mexico
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Immanneni C, Calame D, Jiao S, Emrick LT, Holmgren M, Yano ST. ATP1A3 Disease Spectrum Includes Paroxysmal Weakness and Encephalopathy Not Triggered by Fever. Neurol Genet 2024; 10:e200150. [PMID: 38685976 PMCID: PMC11057438 DOI: 10.1212/nxg.0000000000200150] [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: 10/20/2023] [Accepted: 02/23/2024] [Indexed: 05/02/2024]
Abstract
Background and Objectives Heterozygous pathogenic variants in ATP1A3, which encodes the catalytic alpha subunit of neuronal Na+/K+-ATPase, cause primarily neurologic disorders with widely variable features that can include episodic movement deficits. One distinctive presentation of ATP1A3-related disease is recurrent fever-triggered encephalopathy. This can occur with generalized weakness and/or ataxia and is described in the literature as relapsing encephalopathy with cerebellar ataxia. This syndrome displays genotype-phenotype correlation with variants at p.R756 causing temperature sensitivity of ATP1A3. We report clinical and in vitro functional evidence for a similar phenotype not triggered by fever but associated with protein loss-of-function. Methods We describe the phenotype of an individual with de novo occurrence of a novel heterozygous ATP1A3 variant, NM_152296.5:c.388_390delGTG; p.(V130del). We confirmed the pathogenicity of p.V130del by cell survival complementation assay in HEK293 cells and then characterized its functional impact on enzymatic ion transport and extracellular sodium binding by two-electrode voltage clamp electrophysiology in Xenopus oocytes. To determine whether variant enzymes reach the cell surface, we surface-biotinylated oocytes expressing N-tagged ATP1A3. Results The proband is a 7-year-old boy who has had 2 lifetime episodes of paroxysmal weakness, encephalopathy, and ataxia not triggered by fever. He had speech regression and intermittent hand tremors after the second episode but otherwise spontaneously recovered after episodes and is at present developmentally appropriate. The p.V130del variant was identified on clinical trio exome sequencing, which did not reveal any other variants possibly associated with the phenotype. p.V130del eliminated ATP1A3 function in cell survival complementation assay. In Xenopus oocytes, p.V130del variant Na+/K+-ATPases showed complete loss of ion transport activity and marked abnormalities of extracellular Na+ binding at room temperature. Despite this clear loss-of-function effect, surface biotinylation under the same conditions revealed that p.V130del variant enzymes were still present at the oocyte's cell membrane. Discussion This individual's phenotype expands the clinical spectrum of ATP1A3-related recurrent encephalopathy to include presentations without fever-triggered events. The total loss of ion transport function with p.V130del, despite enzyme presence at the cell membrane, indicates that haploinsufficiency can cause relatively mild phenotypes in ATP1A3-related disease.
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Affiliation(s)
- Chetan Immanneni
- From the Sam Houston State University College of Osteopathic Medicine (C.I.), Conroe, TX; Molecular Neurophysiology Unit (C.I., S.J., M.H.), National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, MD; Section of Pediatric Neurology and Developmental Neuroscience (D.C.), Department of Pediatrics; Department of Molecular and Human Genetics (D.C., L.T.E.), Baylor College of Medicine; Texas Children's Hospital (D.C.), Houston, TX; National Human Genome Research Institute (S.T.Y.), National Institutes of Health, Bethesda, MD; and Section of Pediatric Neurology (S.T.Y.), Department of Pediatrics, University of Chicago, IL
| | - Daniel Calame
- From the Sam Houston State University College of Osteopathic Medicine (C.I.), Conroe, TX; Molecular Neurophysiology Unit (C.I., S.J., M.H.), National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, MD; Section of Pediatric Neurology and Developmental Neuroscience (D.C.), Department of Pediatrics; Department of Molecular and Human Genetics (D.C., L.T.E.), Baylor College of Medicine; Texas Children's Hospital (D.C.), Houston, TX; National Human Genome Research Institute (S.T.Y.), National Institutes of Health, Bethesda, MD; and Section of Pediatric Neurology (S.T.Y.), Department of Pediatrics, University of Chicago, IL
| | - Song Jiao
- From the Sam Houston State University College of Osteopathic Medicine (C.I.), Conroe, TX; Molecular Neurophysiology Unit (C.I., S.J., M.H.), National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, MD; Section of Pediatric Neurology and Developmental Neuroscience (D.C.), Department of Pediatrics; Department of Molecular and Human Genetics (D.C., L.T.E.), Baylor College of Medicine; Texas Children's Hospital (D.C.), Houston, TX; National Human Genome Research Institute (S.T.Y.), National Institutes of Health, Bethesda, MD; and Section of Pediatric Neurology (S.T.Y.), Department of Pediatrics, University of Chicago, IL
| | - Lisa T Emrick
- From the Sam Houston State University College of Osteopathic Medicine (C.I.), Conroe, TX; Molecular Neurophysiology Unit (C.I., S.J., M.H.), National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, MD; Section of Pediatric Neurology and Developmental Neuroscience (D.C.), Department of Pediatrics; Department of Molecular and Human Genetics (D.C., L.T.E.), Baylor College of Medicine; Texas Children's Hospital (D.C.), Houston, TX; National Human Genome Research Institute (S.T.Y.), National Institutes of Health, Bethesda, MD; and Section of Pediatric Neurology (S.T.Y.), Department of Pediatrics, University of Chicago, IL
| | - Miguel Holmgren
- From the Sam Houston State University College of Osteopathic Medicine (C.I.), Conroe, TX; Molecular Neurophysiology Unit (C.I., S.J., M.H.), National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, MD; Section of Pediatric Neurology and Developmental Neuroscience (D.C.), Department of Pediatrics; Department of Molecular and Human Genetics (D.C., L.T.E.), Baylor College of Medicine; Texas Children's Hospital (D.C.), Houston, TX; National Human Genome Research Institute (S.T.Y.), National Institutes of Health, Bethesda, MD; and Section of Pediatric Neurology (S.T.Y.), Department of Pediatrics, University of Chicago, IL
| | - Sho T Yano
- From the Sam Houston State University College of Osteopathic Medicine (C.I.), Conroe, TX; Molecular Neurophysiology Unit (C.I., S.J., M.H.), National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, MD; Section of Pediatric Neurology and Developmental Neuroscience (D.C.), Department of Pediatrics; Department of Molecular and Human Genetics (D.C., L.T.E.), Baylor College of Medicine; Texas Children's Hospital (D.C.), Houston, TX; National Human Genome Research Institute (S.T.Y.), National Institutes of Health, Bethesda, MD; and Section of Pediatric Neurology (S.T.Y.), Department of Pediatrics, University of Chicago, IL
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Jacobson MA, Jones LJ, Colussi DJ, Tanaka JC. High-Throughput Ca 2+ Flux Assay To Monitor Cyclic Nucleotide-Gated Channel Activity and Characterize Achromatopsia Mutant Channel Function. ACS Chem Neurosci 2019; 10:3662-3670. [PMID: 31290651 DOI: 10.1021/acschemneuro.9b00231] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Cone photoreceptor cyclic-nucleotide gated channels (CNG) are tetrameric proteins composed of subunits from CNGA3 and CNGB3. These channels transduce light information into electrical signals carried by both Na+ and Ca2+ ions. More than 100 mutations in the CNGA3 gene are associated with the inherited retinal disorder, achromatopsia 2 (ACHM2), which results in attenuation or loss of color vision, daylight blindness, and reduced visual acuity. Classical techniques to measure CNG channel function utilize patch clamp electrophysiology measuring Na currents in the absence of divalent cations, yet intracellular Ca2+ regulates both light and dark adaptation in photoreceptors. We developed a fluorescence-based, high-throughput Ca2+ flux assay using yellow fluorescent protein (YFP) tagged CNGA3 channels expressed in HEK293 cells which allow monitoring for folding defects in mutant channels. The cell permeant cGMP analog, 8-(4-chlorophenylthio)-cGMP (CPT-cGMP), was used to activate Ca2+ flux. The assay was validated using wild-type CNGA3 homomeric and heteromeric channels and ACHM2-associated homomeric mutant CNG channels, CNGA3-R427C, CNGA3-E590K, and CNGA3-L633P. Additionally, we examined two naturally occurring canine mutations causing day-blindness previously studied by patch clamp. We compared the CPT-cGMP K0.5 values of the channels with patch clamp values from previous studies. The assay provides a screen for modulation of gating and/or rescue of trafficking and/or misfolding defects in ACHM2-associated CNG channels. Importantly, the calcium flux assay is advantageous compared to patch clamp as it allows the ability to monitor CNG channel activity in the presence of calcium.
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Affiliation(s)
- Marlene A Jacobson
- Department of Pharmaceutical Sciences, School of Pharmacy , Temple University , Philadelphia , Pennsylvania 19140 , United States
- Moulder Center for Drug Discovery Research, School of Pharmacy , Temple University , Philadelphia , Pennsylvania 19140 , United States
| | - Laura J Jones
- Department of Biology, College of Science and Technology , Temple University , Philadelphia , Pennsylvania 19122 , United States
| | - Dennis J Colussi
- Department of Pharmaceutical Sciences, School of Pharmacy , Temple University , Philadelphia , Pennsylvania 19140 , United States
- Moulder Center for Drug Discovery Research, School of Pharmacy , Temple University , Philadelphia , Pennsylvania 19140 , United States
| | - Jacqueline C Tanaka
- Department of Biology, College of Science and Technology , Temple University , Philadelphia , Pennsylvania 19122 , United States
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Ui M, Harima K, Takei T, Tsumoto K, Tabata KV, Noji H, Endo S, Akiyama K, Muraoka T, Kinbara K. Grafting synthetic transmembrane units to the engineered low-toxicity α-hemolysin to restore its hemolytic activity. MOLECULAR BIOSYSTEMS 2015; 10:3199-206. [PMID: 25267196 DOI: 10.1039/c4mb00405a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The chemical modification of proteins to provide desirable functions and/or structures broadens their possibilities for use in various applications. Usually, proteins can acquire new functions and characteristics, in addition to their original ones, via the introduction of synthetic functional moieties. Here, we adopted a more radical approach to protein modification, i.e., the replacement of a functional domain of proteins with alternative chemical compounds to build "cyborg proteins." As a proof of concept model, we chose staphylococcal α-hemolysin (Hla), which is a well-studied, pore-forming toxin. The hemolytic activity of Hla mutants was dramatically decreased by truncation of the stem domain, which forms a β-barrel pore in the membrane. However, the impaired hemolytic activity was significantly restored by attaching a pyrenyl-maleimide unit to the cysteine residue that was introduced in the remaining stem domain. In contrast, negatively charged fluorescein-maleimide completely abolished the remaining activity of the mutants.
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Affiliation(s)
- Mihoko Ui
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1, Katahira, Aoba-ku, Sendai 980-8577, Japan.
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