1
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Spontarelli K, Young VC, Sweazey R, Padro A, Lee J, Bueso T, Hernandez RM, Kim J, Katz A, Rossignol F, Turner C, Wilczewski CM, Maxwell GL, Holmgren M, Bailoo JD, Yano ST, Artigas P. ATP1A1-linked diseases require a malfunctioning protein product from one allele. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2024; 1871:119572. [PMID: 37659504 DOI: 10.1016/j.bbamcr.2023.119572] [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] [Received: 02/28/2023] [Revised: 07/06/2023] [Accepted: 08/22/2023] [Indexed: 09/04/2023]
Abstract
Heterozygous germline variants in ATP1A1, the gene encoding the α1 subunit of the Na+/K+-ATPase (NKA), have been linked to diseases including primary hyperaldosteronism and the peripheral neuropathy Charcot-Marie-Tooth disease (CMT). ATP1A1 variants that cause CMT induce loss-of-function of NKA. This heterodimeric (αβ) enzyme hydrolyzes ATP to establish transmembrane electrochemical gradients of Na+ and K+ that are essential for electrical signaling and cell survival. Of the 4 catalytic subunit isoforms, α1 is ubiquitously expressed and is the predominant paralog in peripheral axons. Human population sequencing datasets indicate strong negative selection against both missense and protein-null ATP1A1 variants. To test whether haploinsufficiency generated by heterozygous protein-null alleles are sufficient to cause disease, we tested the neuromuscular characteristics of heterozygous Atp1a1+/- knockout mice and their wildtype littermates, while also evaluating if exercise increased CMT penetrance. We found that Atp1a1+/- mice were phenotypically normal up to 18 months of age. Consistent with the observations in mice, we report clinical phenotyping of a healthy adult human who lacks any clinical features of known ATP1A1-related diseases despite carrying a plasma-membrane protein-null early truncation variant, p.Y148*. Taken together, these results suggest that a malfunctioning gene product is required for disease induction by ATP1A1 variants and that if any pathology is associated with protein-null variants, they may display low penetrance or high age of onset.
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Affiliation(s)
- Kerri Spontarelli
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Victoria C Young
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Ryan Sweazey
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Alexandria Padro
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Jeannie Lee
- Department of Neurology, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Tulio Bueso
- Department of Neurology, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Roberto M Hernandez
- Department of Neurology, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Jongyeol Kim
- Department of Neurology, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | - Alexander Katz
- NIH Reverse Phenotyping Core, National Institutes of Health, Bethesda, MD, USA; National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Francis Rossignol
- National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Clesson Turner
- NIH Reverse Phenotyping Core, National Institutes of Health, Bethesda, MD, USA; National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Caralynn M Wilczewski
- NIH Reverse Phenotyping Core, National Institutes of Health, Bethesda, MD, USA; National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - George L Maxwell
- Women's Health Integrated Research Center, Inova Health System, Falls Church, VA, USA
| | - Miguel Holmgren
- Molecular Neurophysiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Jeremy D Bailoo
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX, USA.
| | - Sho T Yano
- National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA; Molecular Neurophysiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA; Current address: Section of Pediatric Neurology, Department of Pediatrics, University of Chicago, Chicago, IL, USA.
| | - Pablo Artigas
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX, USA.
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2
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Mahato DR, Andersson M. Dynamic lipid interactions in the plasma membrane Na +,K +-ATPase. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2023; 1870:119545. [PMID: 37481079 DOI: 10.1016/j.bbamcr.2023.119545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 06/12/2023] [Accepted: 07/13/2023] [Indexed: 07/24/2023]
Abstract
The function of ion-transporting Na+,K+-ATPases depends on the surrounding lipid environment in biological membranes. Two established lipid-interaction sites A and B within the transmembrane domain have been observed to induce protein activation and stabilization, respectively. In addition, lipid-mediated inhibition has been assigned to a site C, but with the exact location not experimentally confirmed. Also, possible effects on lipid interactions by disease mutants dwelling in the membrane-protein interface remain relatively uncharacterized. We simulated human Na+,K+-ATPase α1β1FXYD homology models in E1 and E2 states in an asymmetric, multicomponent plasma membrane to determine both wild-type and disease mutant lipid-protein interactions. The simulated wild-type lipid interactions at the established sites A and B were in agreement with experimental results thereby confirming the membrane-protein model system. The less well-characterized, proposed inhibitory site C was dominated by lipids lacking inhibitory properties. Instead, two sites hosting inhibitory lipids were identified at the extracellular side and also a cytoplasmic CHL-binding site that provide putative alternative locations of Na+,K+-ATPase inhibition. Three disease mutations, Leu302Arg, Glu840Arg and Met859Arg resided in the lipid-protein interface and caused drastic changes in the lipid interactions. The simulation results show that lipid interactions to the human Na+,K+-ATPase α1β1FXYD protein in the plasma membrane are highly state-dependent and can be disturbed by disease mutations located in the lipid interface, which can open up for new venues to understand genetic disorders.
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Affiliation(s)
- Dhani Ram Mahato
- Department of Chemistry, Umeå University, Umeå, Sweden; Institut de Química Computacional i Catàlisi, Universitat de Girona, Girona, 17003, Spain
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3
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Spontarelli K, Young VC, Sweazey R, Padro A, Lee J, Bueso T, Hernandez RM, Kim J, Katz A, Rossignol F, Turner C, Wilczewski CM, Maxwell GL, Holmgren M, Bailoo JD, Yano ST, Artigas P. ATP1A1 -linked diseases require a malfunctioning protein product from one allele. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.05.531165. [PMID: 37090550 PMCID: PMC10120656 DOI: 10.1101/2023.03.05.531165] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
Abstract
Heterozygous germline variants in ATP1A1 , the gene encoding the α1 subunit of the Na + /K + -ATPase (NKA), have been linked to diseases including primary hyperaldosteronism and the peripheral neuropathy Charcot-Marie-Tooth disease (CMT). ATP1A1 variants that cause CMT induce loss-of-function of NKA. This heterodimeric (αβ) enzyme hydrolyzes ATP to establish transmembrane electrochemical gradients of Na + and K + that are essential for electrical signaling and cell survival. Of the 4 catalytic subunit isoforms, α1 is ubiquitously expressed and is the predominant paralog in peripheral axons. Human population sequencing datasets indicate strong negative selection against both missense and protein-null ATP1A1 variants. To test whether haploinsufficiency generated by heterozygous protein-null alleles are sufficient to cause disease, we tested the neuromuscular characteristics of heterozygous Atp1a1 +/- knockout mice and their wildtype littermates, while also evaluating if exercise increased CMT penetrance. We found that Atp1a1 +/- mice were phenotypically normal up to 18 months of age. Consistent with the observations in mice, we report clinical phenotyping of a healthy adult human who lacks any clinical features of known ATP1A1 -related diseases despite carrying a protein-null early truncation variant, p.Y148*. Taken together, these results suggest that a malfunctioning gene product is required for disease induction by ATP1A1 variants and that if any pathology is associated with protein-null variants, they may display low penetrance or high age of onset.
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4
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Meyer DJ, Díaz-García CM, Nathwani N, Rahman M, Yellen G. The Na +/K + pump dominates control of glycolysis in hippocampal dentate granule cells. eLife 2022; 11:e81645. [PMID: 36222651 PMCID: PMC9592084 DOI: 10.7554/elife.81645] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2022] [Accepted: 10/11/2022] [Indexed: 11/13/2022] Open
Abstract
Cellular ATP that is consumed to perform energetically expensive tasks must be replenished by new ATP through the activation of metabolism. Neuronal stimulation, an energetically demanding process, transiently activates aerobic glycolysis, but the precise mechanism underlying this glycolysis activation has not been determined. We previously showed that neuronal glycolysis is correlated with Ca2+ influx, but is not activated by feedforward Ca2+ signaling (Díaz-García et al., 2021a). Since ATP-powered Na+ and Ca2+ pumping activities are increased following stimulation to restore ion gradients and are estimated to consume most neuronal ATP, we aimed to determine if they are coupled to neuronal glycolysis activation. By using two-photon imaging of fluorescent biosensors and dyes in dentate granule cell somas of acute mouse hippocampal slices, we observed that production of cytoplasmic NADH, a byproduct of glycolysis, is strongly coupled to changes in intracellular Na+, while intracellular Ca2+ could only increase NADH production if both forward Na+/Ca2+ exchange and Na+/K+ pump activity were intact. Additionally, antidromic stimulation-induced intracellular [Na+] increases were reduced >50% by blocking Ca2+ entry. These results indicate that neuronal glycolysis activation is predominantly a response to an increase in activity of the Na+/K+ pump, which is strongly potentiated by Na+ influx through the Na+/Ca2+ exchanger during extrusion of Ca2+ following stimulation.
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Affiliation(s)
- Dylan J Meyer
- Department of Neurobiology, Harvard Medical SchoolBostonUnited States
| | | | - Nidhi Nathwani
- Department of Neurobiology, Harvard Medical SchoolBostonUnited States
| | - Mahia Rahman
- Department of Neurobiology, Harvard Medical SchoolBostonUnited States
| | - Gary Yellen
- Department of Neurobiology, Harvard Medical SchoolBostonUnited States
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Moreno C, Jiao S, Yano S, Holmgren M. Disease mutations of human α3 Na +/K +-ATPase define extracellular Na + binding/occlusion kinetics at ion binding site III. PNAS NEXUS 2022; 1:pgac205. [PMID: 36304555 PMCID: PMC9585393 DOI: 10.1093/pnasnexus/pgac205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 09/23/2022] [Indexed: 11/06/2022]
Abstract
Na+/K+-ATPase, which creates transmembrane electrochemical gradients by exchanging 3 Na+ for 2 K+, is central to the pathogenesis of neurological diseases such as alternating hemiplegia of childhood. Although Na+/K+-ATPase has 3 distinct ion binding sites I-III, the difficulty of distinguishing ion binding events at each site from the others hinders kinetic study of these transitions. Here, we show that binding of Na+ at each site in the human α3 Na+/K+-ATPase can be resolved using extracellular Na+-mediated transient currents. When Na+/K+-ATPase is constrained to bind and release only Na+, three kinetic components: fast, medium, and slow, can be isolated, presumably corresponding to the protein dynamics associated with the binding (or release depending on the voltage step direction) and the occlusion (or deocclusion) of each of the 3 Na+. Patient-derived mutations of residues which coordinate Na+ at site III exclusively impact the slow component, demonstrating that site III is crucial for deocclusion and release of the first Na+ into the extracellular milieu. These results advance understanding of Na+/K+-ATPase mutation pathogenesis and provide a foundation for study of individual ions' binding kinetics.
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Affiliation(s)
- Cristina Moreno
- Molecular Neurophysiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Song Jiao
- Molecular Neurophysiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA
| | - Sho Yano
- Molecular Neurophysiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA,Medical Genetics and Genomic Medicine Training Program, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Miguel Holmgren
- Correspondence should be addressed: Miguel Holmgren, Ph.D. Molecular Neurophysiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA. Tel: +1-(301) 451-6259; E-mail:
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6
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Spontarelli K, Infield DT, Nielsen HN, Holm R, Young VC, Galpin JD, Ahern CA, Vilsen B, Artigas P. Role of a conserved ion-binding site tyrosine in ion selectivity of the Na+/K+ pump. J Gen Physiol 2022; 154:e202113039. [PMID: 35657726 PMCID: PMC9171065 DOI: 10.1085/jgp.202113039] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 04/19/2022] [Accepted: 05/16/2022] [Indexed: 01/07/2023] Open
Abstract
The essential transmembrane Na+ and K+ gradients in animal cells are established by the Na+/K+ pump, a P-type ATPase that exports three Na+ and imports two K+ per ATP hydrolyzed. The mechanism by which the Na+/K+ pump distinguishes between Na+ and K+ at the two membrane sides is poorly understood. Crystal structures identify two sites (sites I and II) that bind Na+ or K+ and a third (site III) specific for Na+. The side chain of a conserved tyrosine at site III of the catalytic α-subunit (Xenopus-α1 Y780) has been proposed to contribute to Na+ binding by cation-π interaction. We substituted Y780 with natural and unnatural amino acids, expressed the mutants in Xenopus oocytes and COS-1 cells, and used electrophysiology and biochemistry to evaluate their function. Substitutions disrupting H-bonds impaired Na+ interaction, while Y780Q strengthened it, likely by H-bond formation. Utilizing the non-sense suppression method previously used to incorporate unnatural derivatives in ion channels, we were able to analyze Na+/K+ pumps with fluorinated tyrosine or phenylalanine derivatives inserted at position 780 to diminish cation-π interaction strength. In line with the results of the analysis of mutants with natural amino acid substitutions, the results with the fluorinated derivatives indicate that Na+-π interaction with the phenol ring at position 780 contributes minimally, if at all, to the binding of Na+. All Y780 substitutions decreased K+ apparent affinity, highlighting that a state-dependent H-bond network is essential for the selectivity switch at sites I and II when the pump changes conformational state.
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Affiliation(s)
- Kerri Spontarelli
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX
| | - Daniel T. Infield
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA
| | - Hang N. Nielsen
- Department of Biomedicine, Aarhus University, Aarhus C, Denmark
| | - Rikke Holm
- Department of Biomedicine, Aarhus University, Aarhus C, Denmark
| | - Victoria C. Young
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX
| | - Jason D. Galpin
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA
| | - Christopher A. Ahern
- Department of Molecular Physiology and Biophysics, University of Iowa, Iowa City, IA
| | - Bente Vilsen
- Department of Biomedicine, Aarhus University, Aarhus C, Denmark
| | - Pablo Artigas
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, TX
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7
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Kasas AHE, Farag IM, Darwish HR, Soliman YA, Nagar EME, Ibrahim MA, Kamel S, Warda M. Molecular characterization of alpha subunit 1 of sodium pump (ATP1A1) gene in Camelus dromedarius: its differential tissue expression potentially interprets the role in osmoregulation. Mol Biol Rep 2022; 49:3849-3861. [PMID: 35235155 DOI: 10.1007/s11033-022-07232-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Accepted: 02/04/2022] [Indexed: 12/19/2022]
Abstract
BACKGROUND Dromedary or one-humped camel (Camelus dromedarius) is distinctively acclimatized to survive the arid conditions of the desert environment. It has an excellent ability to compete dehydration with substantial tolerance for rapid dehydration. Therefore, it offers an excellent model for studying osmoregulation. Molecular characterization of Na+/K+ ATPase as a central regulator of electrolyte normohemostasis affords a better understanding of this mechanism in camel. Here is the first to resolve the full-length of alpha-1 subunit of sodium pump (ATP1A1) gene with its differential expression in dromedary tissues. RESULTS The nucleotide sequence for the recovered full cDNA of ATP1A1was submitted to the GenBank (NCBI GenBank accession #MW628635) and bioinformatically analyzed. The cDNA sequence was of 3760 bp length with an open reading frame (ORF) of 3066 bp encoding a putative 1021 amino acids polypeptide with a molecular mass of 112696 Da. Blast search analysis revealed the shared high similarity of dromedary ATP1A1gene with other known ATP1A1genes in different species. The comparative analysis of its protein sequence confirmed the high identity with other mammalian ATP1A1 proteins. Further transcriptomic investigation for different organs was performed by real-time PCR to compare its level of expression among different organs. The results confirm a direct function between the ATP1A1 gene expression and the order of vital performance of these organs. The expression of ATP1A1 mRNA in the adrenal gland and brain was significantly higher than that in the other organs. The noticed down expression in camel kidney concomitant with overexpression in the adrenal cortex might interpret how dromedary expels access sodium without water loss with relative high ability to restrain mineralocorticoid-induced sodium retention on drinking salty water. CONCLUSION The results reflect the importance of sodium pump in these organs. Na+/K+ ATPase in the adrenal gland and brain than other organs.
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Affiliation(s)
- A H El Kasas
- Department of Cell Biology, National Research Center, Dokki, Giza, 12622, Egypt
| | - I M Farag
- Department of Cell Biology, National Research Center, Dokki, Giza, 12622, Egypt
| | - H R Darwish
- Department of Cell Biology, National Research Center, Dokki, Giza, 12622, Egypt
| | - Y A Soliman
- Central Lab for Evaluation of Veterinary Biologics (CLEVB), Agriculture Research Center (ARC), Cairo, Egypt
| | - E M El Nagar
- Central Lab for Evaluation of Veterinary Biologics (CLEVB), Agriculture Research Center (ARC), Cairo, Egypt
| | - Marwa A Ibrahim
- Department of Biochemistry and Molecular Biology, Faculty of Veterinary Medicine, Cairo University, Giza, 12211, Egypt
| | - Shaimaa Kamel
- Department of Biochemistry and Molecular Biology, Faculty of Veterinary Medicine, Cairo University, Giza, 12211, Egypt
| | - Mohamad Warda
- Department of Biochemistry and Molecular Biology, Faculty of Veterinary Medicine, Cairo University, Giza, 12211, Egypt.
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8
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Ygberg S, Akkuratov EE, Howard RJ, Taylan F, Jans DC, Mahato DR, Katz A, Kinoshita PF, Portal B, Nennesmo I, Lindskog M, Karlish SJD, Andersson M, Lindstrand A, Brismar H, Aperia A. A missense mutation converts the Na +,K +-ATPase into an ion channel and causes therapy-resistant epilepsy. J Biol Chem 2021; 297:101355. [PMID: 34717959 PMCID: PMC8637647 DOI: 10.1016/j.jbc.2021.101355] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 10/14/2021] [Accepted: 10/25/2021] [Indexed: 11/16/2022] Open
Abstract
The ion pump Na+,K+-ATPase is a critical determinant of neuronal excitability; however, its role in the etiology of diseases of the central nervous system (CNS) is largely unknown. We describe here the molecular phenotype of a Trp931Arg mutation of the Na+,K+-ATPase catalytic α1 subunit in an infant diagnosed with therapy-resistant lethal epilepsy. In addition to the pathological CNS phenotype, we also detected renal wasting of Mg2+. We found that membrane expression of the mutant α1 protein was low, and ion pumping activity was lost. Arginine insertion into membrane proteins can generate water-filled pores in the plasma membrane, and our molecular dynamic (MD) simulations of the principle states of Na+,K+-ATPase transport demonstrated massive water inflow into mutant α1 and destabilization of the ion-binding sites. MD simulations also indicated that a water pathway was created between the mutant arginine residue and the cytoplasm, and analysis of oocytes expressing mutant α1 detected a nonspecific cation current. Finally, neurons expressing mutant α1 were observed to be depolarized compared with neurons expressing wild-type protein, compatible with a lowered threshold for epileptic seizures. The results imply that Na+,K+-ATPase should be considered a neuronal locus minoris resistentia in diseases associated with epilepsy and with loss of plasma membrane integrity.
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Affiliation(s)
- Sofia Ygberg
- Neuropediatric Unit, Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden; Centre for Inherited Metabolic Diseases (CMMS), Karolinska University Hospital, Stockholm, Sweden
| | - Evgeny E Akkuratov
- Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, Stockholm, Sweden
| | - Rebecca J Howard
- Science for Life Laboratory, Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
| | - Fulya Taylan
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden; Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
| | - Daniel C Jans
- Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, Stockholm, Sweden
| | | | - Adriana Katz
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovoth, Israel
| | - Paula F Kinoshita
- Department of Pharmacology, Institute of Biomedical Science, University of São Paulo, São Paulo, Brazil
| | - Benjamin Portal
- Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
| | - Inger Nennesmo
- Department of Pathology, Karolinska University Hospital, Stockholm, Sweden
| | - Maria Lindskog
- Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, Stockholm, Sweden
| | - Steven J D Karlish
- Department of Biomolecular Sciences, Weizmann Institute of Science, Rehovoth, Israel
| | | | - Anna Lindstrand
- Department of Molecular Medicine and Surgery, Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden; Department of Clinical Genetics, Karolinska University Hospital, Stockholm, Sweden
| | - Hjalmar Brismar
- Science for Life Laboratory, Department of Applied Physics, Royal Institute of Technology, Stockholm, Sweden; Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden.
| | - Anita Aperia
- Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden
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9
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Meyer DJ, Bijlani S, de Sautu M, Spontarelli K, Young VC, Gatto C, Artigas P. FXYD protein isoforms differentially modulate human Na/K pump function. J Gen Physiol 2021; 152:211559. [PMID: 33231612 PMCID: PMC7690937 DOI: 10.1085/jgp.202012660] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 10/29/2020] [Indexed: 12/28/2022] Open
Abstract
Tight regulation of the Na/K pump is essential for cellular function because this heteromeric protein builds and maintains the electrochemical gradients for Na+ and K+ that energize electrical signaling and secondary active transport. We studied the regulation of the ubiquitous human α1β1 pump isoform by five human FXYD proteins normally located in muscle, kidney, and neurons. The function of Na/K pump α1β1 expressed in Xenopus oocytes with or without FXYD isoforms was evaluated using two-electrode voltage clamp and patch clamp. Through evaluation of the partial reactions in the absence of K+ but presence of Na+ in the external milieu, we demonstrate that each FXYD subunit alters the equilibrium between E1P(3Na) and E2P, the phosphorylated conformations with Na+ occluded and free from Na+, respectively, thereby altering the apparent affinity for Na+. This modification of Na+ interaction shapes the small effects of FXYD proteins on the apparent affinity for external K+ at physiological Na+. FXYD6 distinctively accelerated both the Na+-deocclusion and the pump-turnover rates. All FXYD isoforms altered the apparent affinity for intracellular Na+ in patches, an effect that was observed only in the presence of intracellular K+. Therefore, FXYD proteins alter the selectivity of the pump for intracellular ions, an effect that could be due to the altered equilibrium between E1 and E2, the two major pump conformations, and/or to small changes in ion affinities that are exacerbated when both ions are present. Lastly, we observed a drastic reduction of Na/K pump surface expression when it was coexpressed with FXYD1 or FXYD6, with the former being relieved by injection of PKA's catalytic subunit into the oocyte. Our results indicate that a prominent effect of FXYD1 and FXYD6, and plausibly other FXYDs, is the regulation of Na/K pump trafficking.
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Affiliation(s)
- Dylan J Meyer
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock TX
| | - Sharan Bijlani
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock TX
| | - Marilina de Sautu
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock TX
| | - Kerri Spontarelli
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock TX
| | - Victoria C Young
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock TX
| | - Craig Gatto
- School of Biological Sciences, Illinois State University. Normal, IL
| | - Pablo Artigas
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock TX
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10
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Biondo ED, Spontarelli K, Ababioh G, Méndez L, Artigas P. Diseases caused by mutations in the Na +/K + pump α1 gene ATP1A1. Am J Physiol Cell Physiol 2021; 321:C394-C408. [PMID: 34232746 DOI: 10.1152/ajpcell.00059.2021] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Human cell survival requires function of the Na+/K+ pump; the heteromeric protein that hydrolyzes ATP to extrude Na+ and import K+ across the plasmalemma, thereby building and maintaining these ions' electrochemical gradients. Numerous dominant diseases caused by mutations in genes encoding for Na+/K+ pump catalytic (α) subunit isoforms highlight the importance of this protein. Here, we review literature describing disorders caused by missense mutations in ATP1A1, the gene encoding the ubiquitously expressed α1 isoform of the Na+/K+ pump. These various maladies include primary aldosteronism with secondary hypertension, an endocrine syndrome, Charcot-Marie-Tooth disease, a peripheral neuropathy, complex spastic paraplegia, another neuromuscular disorder, as well as hypomagnesemia accompanied by seizures and cognitive delay, a condition affecting the renal and central nervous systems. This article focuses on observed commonalities among these mutations' functional effects, as well as on the special characteristics that enable each particular mutation to exclusively affect a certain system, without affecting others. In this respect, it is clear how somatic mutations localized to adrenal adenomas increase aldosterone production without compromising other systems. However, it remains largely unknown how and why some but not all de novo germline or familial mutations (where the mutant must be expressed in numerous tissues) produce a specific disease and not the other diseases. We propose hypotheses to explain this observation and the approaches that we think will drive future research on these debilitating disorders to develop novel patient-specific treatments by combining the use of heterologous protein-expression systems, patient-derived pluripotent cells, and gene-edited cell and mouse models.
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Affiliation(s)
- Elisa D Biondo
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Kerri Spontarelli
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Giovanna Ababioh
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Lois Méndez
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, Texas
| | - Pablo Artigas
- Department of Cell Physiology and Molecular Biophysics, Center for Membrane Protein Research, Texas Tech University Health Sciences Center, Lubbock, Texas
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Nanba K, Yamazaki Y, Bick N, Onodera K, Tezuka Y, Omata K, Ono Y, Blinder AR, Tomlins SA, Rainey WE, Satoh F, Sasano H. Prevalence of Somatic Mutations in Aldosterone-Producing Adenomas in Japanese Patients. J Clin Endocrinol Metab 2020; 105:5897223. [PMID: 32844168 PMCID: PMC7947976 DOI: 10.1210/clinem/dgaa595] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 08/24/2020] [Indexed: 11/19/2022]
Abstract
CONTEXT Results of previous studies demonstrated clear racial differences in the prevalence of somatic mutations among patients with aldosterone-producing adenoma (APA). For instance, those in East Asian countries have a high prevalence of somatic mutations in KCNJ5, whereas somatic mutations in other aldosterone-driving genes are rare. OBJECTIVES To determine somatic mutation prevalence in Japanese APA patients using an aldosterone synthase (CYP11B2) immunohistochemistry (IHC)-guided sequencing approach. METHOD Patients with a unilateral form of primary aldosteronism who underwent adrenalectomy at the Tohoku University Hospital were studied. Based on CYP11B2 immunolocalization of resected adrenals, genomic DNA was isolated from the relevant positive area of 10% formalin-fixed, paraffin-embedded tissue of the APAs. Somatic mutations in aldosterone-driving genes were studied in APAs by direct Sanger sequencing and targeted next-generation sequencing. RESULTS CYP11B2 IHC-guided sequencing determined APA-related somatic mutations in 102 out of 106 APAs (96%). Somatic KCNJ5 mutation was the most frequent genetic alteration (73%) in this cohort of Japanese patients. Somatic mutations in other aldosterone-driving genes were also identified: CACNA1D (14%), ATP1A1 (5%), ATP2B3 (4%), and CACNA1H (1%), including 2 previously unreported mutations. KCNJ5 mutations were more often detected in APAs from female patients compared with those from male patients [95% (36/38) vs 60% (41/68); P < 0.0001]. CONCLUSION IHC-guided sequencing defined somatic mutations in over 95% of Japanese APAs. While the dominance of KCNJ5 mutations in this particular cohort was confirmed, a significantly higher KCNJ5 prevalence was detected in female patients. This study provides a better understanding of genetic spectrum of Japanese APA patients.
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Affiliation(s)
- Kazutaka Nanba
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
- Department of Endocrinology and Metabolism, National Hospital Organization Kyoto Medical Center, Kyoto, Japan
| | - Yuto Yamazaki
- Department of Pathology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Nolan Bick
- Department of Pathology, University of Michigan, Ann Arbor, Michigan
| | - Kei Onodera
- Department of Pathology, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Yuta Tezuka
- Division of Nephrology, Endocrinology and Vascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
- Division of Clinical Hypertension, Endocrinology and Metabolism, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Kei Omata
- Division of Nephrology, Endocrinology and Vascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan
- Division of Clinical Hypertension, Endocrinology and Metabolism, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Yoshikiyo Ono
- Division of Nephrology, Endocrinology and Vascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan
- Division of Clinical Hypertension, Endocrinology and Metabolism, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Amy R Blinder
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
| | - Scott A Tomlins
- Department of Pathology, University of Michigan, Ann Arbor, Michigan
- Rogel Cancer Center, University of Michigan, Ann Arbor, Michigan
- Michigan Center for Translational Pathology, University of Michigan, Ann Arbor, Michigan
- Department of Urology, University of Michigan, Ann Arbor, Michigan
| | - William E Rainey
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan
- Division of Metabolism, Endocrinology, and Diabetes, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Fumitoshi Satoh
- Division of Nephrology, Endocrinology and Vascular Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan
- Division of Clinical Hypertension, Endocrinology and Metabolism, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Hironobu Sasano
- Department of Pathology, Tohoku University Graduate School of Medicine, Sendai, Japan
- Correspondence and Reprint Requests: Hironobu Sasano, MD, PhD, Department of Pathology, Tohoku University Graduate School of Medicine, Sendai 980-8575, Japan. E-mail:
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Moreno C, Yano S, Bezanilla F, Latorre R, Holmgren M. Transient Electrical Currents Mediated by the Na +/K +-ATPase: A Tour from Basic Biophysics to Human Diseases. Biophys J 2020; 119:236-242. [PMID: 32579966 PMCID: PMC7376075 DOI: 10.1016/j.bpj.2020.06.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 04/06/2020] [Accepted: 06/03/2020] [Indexed: 01/14/2023] Open
Abstract
The Na+/K+-ATPase is a chemical molecular machine responsible for the movement of Na+ and K+ ions across the cell membrane. These ions are moved against their electrochemical gradients, so the protein uses the free energy of ATP hydrolysis to transport them. In fact, the Na+/K+-ATPase is the single largest consumer of energy in most cells. In each pump cycle, the protein sequentially exports 3Na+ out of the cell, then imports 2K+ into the cell at an approximate rate of 200 cycles/s. In each half cycle of the transport process, there is a state in which ions are stably trapped within the permeation pathway of the protein by internal and external gates in their closed states. These gates are required to open alternately; otherwise, passive ion diffusion would be a wasteful end of the cell's energy. Once one of these gates open, ions diffuse from their binding sites to the accessible milieu, which involves moving through part of the electrical field across the membrane. Consequently, ions generate transient electrical currents first discovered more than 30 years ago. They have been studied in a variety of preparations, including native and heterologous expression systems. Here, we review three decades' worth of work using these transient electrical signals to understand the kinetic transitions of the movement of Na+ and K+ ions through the Na+/K+-ATPase and propose the significance that this work might have to the understanding of the dysfunction of human pump orthologs responsible for some newly discovered neurological pathologies.
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Affiliation(s)
- Cristina Moreno
- Molecular Neurophysiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland
| | - Sho Yano
- Medical Genetics and Genomic Medicine Training Program, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland
| | - Francisco Bezanilla
- Department of Biochemistry and Molecular Biology, University of Chicago, Gordon Center for Integrative Sciences, Chicago, Illinois
| | - Ramon Latorre
- Centro Interdisciplinario de Neurociencia de Valparaíso, Universidad de Valparaíso, Valparaíso, Chile
| | - Miguel Holmgren
- Molecular Neurophysiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland.
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