1
|
Nordahl L, Akkuratov EE, Heimgärtner J, Schach K, Meineke B, Elsässer S, Wennmalm S, Brismar H. Detection and quantification of Na,K-ATPase dimers in the plasma membrane of living cells by FRET-FCS. Biochim Biophys Acta Gen Subj 2024; 1868:130619. [PMID: 38643888 DOI: 10.1016/j.bbagen.2024.130619] [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: 01/04/2024] [Revised: 03/25/2024] [Accepted: 04/12/2024] [Indexed: 04/23/2024]
Abstract
The sodium potassium pump, Na,K-ATPase (NKA), is an integral plasma membrane protein, expressed in all eukaryotic cells. It is responsible for maintaining the transmembrane Na+ gradient and is the major determinant of the membrane potential. Self-interaction and oligomerization of NKA in cell membranes has been proposed and discussed but is still an open question. Here, we have used a combination of FRET and Fluorescence Correlation Spectroscopy, FRET-FCS, to analyze NKA in the plasma membrane of living cells. Click chemistry was used to conjugate the fluorescent labels Alexa 488 and Alexa 647 to non-canonical amino acids introduced in the NKA α1 and β1 subunits. We demonstrate that FRET-FCS can detect an order of magnitude lower concentration of green-red labeled protein pairs in a single-labeled red and green background than what is possible with cross-correlation (FCCS). We show that a significant fraction of NKA is expressed as a dimer in the plasma membrane. We also introduce a method to estimate not only the number of single and double labeled NKA, but the number of unlabeled, endogenous NKA and estimate the density of endogenous NKA at the plasma membrane to 1400 ± 800 enzymes/μm2.
Collapse
Affiliation(s)
- Linnea Nordahl
- Science for Life Laboratory, Department of Applied Physics, KTH Royal Institute of Technology, Box 1031, 171 21 Solna, Sweden
| | - Evgeny E Akkuratov
- University of Oxford, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, Oxford OX3 9DS, UK
| | - Johannes Heimgärtner
- Science for Life Laboratory, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Box 1031, 171 21 Solna, Sweden
| | - Katja Schach
- Graduate Training Centre of Neuroscience, University of Tübingen, Otfried-Müller-Str. 27, 72076 Tübingen, Germany
| | - Birthe Meineke
- Science for Life Laboratory, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Box 1031, 171 21 Solna, Sweden
| | - Simon Elsässer
- Science for Life Laboratory, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Box 1031, 171 21 Solna, Sweden
| | - Stefan Wennmalm
- Science for Life Laboratory, Department of Applied Physics, KTH Royal Institute of Technology, Box 1031, 171 21 Solna, Sweden.
| | - Hjalmar Brismar
- Science for Life Laboratory, Department of Applied Physics, KTH Royal Institute of Technology, Box 1031, 171 21 Solna, Sweden; Science for Life Laboratory, Department of Women's and Children's Health, Karolinska Institutet, Box 1031, 171 21 Solna, Sweden
| |
Collapse
|
2
|
Vishnu N, Venkatesan M, Madaris TR, Venkateswaran MK, Stanley K, Ramachandran K, Chidambaram A, Madesh AK, Yang W, Nair J, Narkunan M, Muthukumar T, Karanam V, Joseph LC, Le A, Osidele A, Aslam MI, Morrow JP, Malicdan MC, Stathopulos PB, Madesh M. ERMA (TMEM94) is a P-type ATPase transporter for Mg 2+ uptake in the endoplasmic reticulum. Mol Cell 2024; 84:1321-1337.e11. [PMID: 38513662 PMCID: PMC10997467 DOI: 10.1016/j.molcel.2024.02.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2023] [Revised: 10/16/2023] [Accepted: 02/27/2024] [Indexed: 03/23/2024]
Abstract
Intracellular Mg2+ (iMg2+) is bound with phosphometabolites, nucleic acids, and proteins in eukaryotes. Little is known about the intracellular compartmentalization and molecular details of Mg2+ transport into/from cellular organelles such as the endoplasmic reticulum (ER). We found that the ER is a major iMg2+ compartment refilled by a largely uncharacterized ER-localized protein, TMEM94. Conventional and AlphaFold2 predictions suggest that ERMA (TMEM94) is a multi-pass transmembrane protein with large cytosolic headpiece actuator, nucleotide, and phosphorylation domains, analogous to P-type ATPases. However, ERMA uniquely combines a P-type ATPase domain and a GMN motif for ERMg2+ uptake. Experiments reveal that a tyrosine residue is crucial for Mg2+ binding and activity in a mechanism conserved in both prokaryotic (mgtB and mgtA) and eukaryotic Mg2+ ATPases. Cardiac dysfunction by haploinsufficiency, abnormal Ca2+ cycling in mouse Erma+/- cardiomyocytes, and ERMA mRNA silencing in human iPSC-cardiomyocytes collectively define ERMA as an essential component of ERMg2+ uptake in eukaryotes.
Collapse
Affiliation(s)
- Neelanjan Vishnu
- Department of Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA; Center for Mitochondrial Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA
| | - Manigandan Venkatesan
- Department of Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA; Center for Mitochondrial Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA
| | - Travis R Madaris
- Department of Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA; Center for Mitochondrial Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA
| | - Mridula K Venkateswaran
- Department of Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA; Center for Mitochondrial Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA
| | - Kristen Stanley
- Department of Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA; Center for Mitochondrial Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA
| | - Karthik Ramachandran
- Department of Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA; Center for Mitochondrial Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA
| | - Adhishree Chidambaram
- Department of Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA; Center for Mitochondrial Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA
| | - Abitha K Madesh
- Department of Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA; Center for Mitochondrial Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA
| | - Wenli Yang
- Institute for Regenerative Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Jyotsna Nair
- Department of Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA; Center for Mitochondrial Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA
| | - Melanie Narkunan
- Department of Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA; Center for Mitochondrial Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA
| | - Tharani Muthukumar
- Department of Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA; Center for Mitochondrial Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA
| | - Varsha Karanam
- Department of Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA; Center for Mitochondrial Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA
| | - Leroy C Joseph
- Department of Medicine, College of Physicians and Surgeons of Columbia University, 650 W 168 Street, New York, NY 10032, USA
| | - Amy Le
- Department of Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA; Center for Mitochondrial Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA
| | - Ayodeji Osidele
- Department of Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA; Center for Mitochondrial Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA
| | - M Imran Aslam
- Department of Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA; Center for Mitochondrial Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA
| | - John P Morrow
- Department of Medicine, College of Physicians and Surgeons of Columbia University, 650 W 168 Street, New York, NY 10032, USA
| | - May C Malicdan
- Section of Human Biochemical Genetics, Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892, USA; NIH Undiagnosed Diseases Program, Office of the Clinical Director, National Human Genome Research Institute, and the Common Fund, National Institutes of Health, Bethesda, MD 20892, USA
| | - Peter B Stathopulos
- Department of Physiology and Pharmacology, Western University, London, ON N6A 5C1, Canada
| | - Muniswamy Madesh
- Department of Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA; Center for Mitochondrial Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA.
| |
Collapse
|
3
|
Zeinert R, Zhou F, Franco P, Zöller J, Lessen HJ, Aravind L, Langer JD, Sodt AJ, Storz G, Matthies D. Magnesium Transporter MgtA revealed as a Dimeric P-type ATPase. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.28.582502. [PMID: 38464158 PMCID: PMC10925321 DOI: 10.1101/2024.02.28.582502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Magnesium (Mg2+) uptake systems are present in all domains of life given the vital role of this ion. Bacteria acquire Mg2+ via conserved Mg2+ channels and transporters. The transporters are required for growth when Mg2+ is limiting or during bacterial pathogenesis, but, despite their significance, there are no known structures for these transporters. Here we report the first structure of the Mg2+ transporter MgtA solved by single particle cryo-electron microscopy (cryo-EM). Using mild membrane extraction, we obtained high resolution structures of both a homodimeric form (2.9 Å), the first for a P-type ATPase, and a monomeric form (3.6 Å). Each monomer unit of MgtA displays a structural architecture that is similar to other P-type ATPases with a transmembrane domain and two soluble domains. The dimer interface consists of contacts between residues in adjacent soluble nucleotide binding and phosphotransfer regions of the haloacid dehalogenase (HAD) domain. We suggest oligomerization is a conserved structural feature of the diverse family of P-type ATPase transporters. The ATP binding site and conformational dynamics upon nucleotide binding to MgtA were characterized using a combination of cryo-EM, molecular dynamics simulations, hydrogen-deuterium exchange mass spectrometry, and mutagenesis. Our structure also revealed a Mg2+ ion in the transmembrane segments, which, when combined with sequence conservation and mutagenesis studies, allowed us to propose a model for Mg2+ transport across the lipid bilayer. Finally, our work revealed the N-terminal domain structure and cytoplasmic Mg2+ binding sites, which have implications for related P-type ATPases defective in human disease.
Collapse
Affiliation(s)
- Rilee Zeinert
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda MD 20892, USA
| | - Fei Zhou
- Unit on Structural Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda MD 20892, USA
| | - Pedro Franco
- Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Jonathan Zöller
- Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Henry J. Lessen
- Unit on Membrane Chemical Physics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda MD 20892, USA
| | - L. Aravind
- National Center for Biotechnology Information, National Institutes of Health, Bethesda MD 20892, USA
| | - Julian D. Langer
- Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Alexander J. Sodt
- Unit on Membrane Chemical Physics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda MD 20892, USA
| | - Gisela Storz
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda MD 20892, USA
| | - Doreen Matthies
- Unit on Structural Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda MD 20892, USA
| |
Collapse
|
4
|
Šeflová J, Cruz-Cortés C, Guerrero-Serna G, Robia SL, Espinoza-Fonseca LM. Mechanisms for cardiac calcium pump activation by its substrate and a synthetic allosteric modulator using fluorescence lifetime imaging. PNAS NEXUS 2024; 3:pgad453. [PMID: 38222469 PMCID: PMC10785037 DOI: 10.1093/pnasnexus/pgad453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 12/15/2023] [Indexed: 01/16/2024]
Abstract
The discovery of allosteric modulators is an emerging paradigm in drug discovery, and signal transduction is a subtle and dynamic process that is challenging to characterize. We developed a time-correlated single photon-counting imaging approach to investigate the structural mechanisms for small-molecule activation of the cardiac sarcoplasmic reticulum Ca2+-ATPase, a pharmacologically important pump that transports Ca2+ at the expense of adenosine triphosphate (ATP) hydrolysis. We first tested whether the dissociation of sarcoplasmic reticulum Ca2+-ATPase from its regulatory protein phospholamban is required for small-molecule activation. We found that CDN1163, a validated sarcoplasmic reticulum Ca2+-ATPase activator, does not have significant effects on the stability of the sarcoplasmic reticulum Ca2+-ATPase-phospholamban complex. Time-correlated single photon-counting imaging experiments using the nonhydrolyzable ATP analog β,γ-Methyleneadenosine 5'-triphosphate (AMP-PCP) showed ATP is an allosteric modulator of sarcoplasmic reticulum Ca2+-ATPase, increasing the fraction of catalytically competent structures at physiologically relevant Ca2+ concentrations. Unlike ATP, CDN1163 alone has no significant effects on the Ca2+-dependent shifts in the structural populations of sarcoplasmic reticulum Ca2+-ATPase, and it does not increase the pump's affinity for Ca2+ ions. However, we found that CDN1163 enhances the ATP-mediated modulatory effects to increase the population of catalytically competent sarcoplasmic reticulum Ca2+-ATPase structures. Importantly, this structural shift occurs within the physiological window of Ca2+ concentrations at which sarcoplasmic reticulum Ca2+-ATPase operates. We demonstrated that ATP is both a substrate and modulator of sarcoplasmic reticulum Ca2+-ATPase and showed that CDN1163 and ATP act synergistically to populate sarcoplasmic reticulum Ca2+-ATPase structures that are primed for phosphorylation. This study provides novel insights into the structural mechanisms for sarcoplasmic reticulum Ca2+-ATPase activation by its substrate and a synthetic allosteric modulator.
Collapse
Affiliation(s)
- Jaroslava Šeflová
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL 60153, USA
| | - Carlos Cruz-Cortés
- Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Guadalupe Guerrero-Serna
- Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| | - Seth L Robia
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL 60153, USA
| | - L Michel Espinoza-Fonseca
- Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, MI 48109, USA
| |
Collapse
|
5
|
Bovo E, Rebbeck RT, Roopnarine O, Cornea RL, Thomas DD, Zima AV. Regulation of cardiac calcium signaling by newly identified calcium pump modulators. Biochem Biophys Res Commun 2023; 685:149136. [PMID: 37907012 PMCID: PMC10841636 DOI: 10.1016/j.bbrc.2023.149136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 10/09/2023] [Accepted: 10/18/2023] [Indexed: 11/02/2023]
Abstract
In cardiomyocytes, the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA2a) is a central component of intracellular Ca2+ regulation. Several heart diseases, including heart failure, are associated with reduced myocardial contraction due to SERCA2a downregulation. Therefore, the need for developing new drugs that could improve SERCA2a function is high. We have recently identified SERCA2a modulators (Compounds 6 and 8) from our screening campaigns and confirmed activation of biochemical SERCA2a ATPase activity and Ca2+ uptake activity. In this study, confocal microscopy and in-cell Ca2+ imaging were used to characterize the effects of these SERCA2a activators on Ca2+ regulation in mouse ventricular myocytes and endoplasmic reticulum (ER) Ca2+ uptake in a HEK293 cell expressing human SERCA2a. Analysis of cytosolic Ca2+ dynamics in cardiomyocytes revealed that both Compounds (6 and 8) increase the action potential-induced Ca2+ transients and sarcoplasmic reticulum (SR) Ca2+ load. While Compound 6 induced a negligible effect on Ca2+ transients invoked by the L-type Ca2+ channel (LTCC) current, Compound 8 increased Ca2+ transients during LTCC activation, suggesting an off-target protein interaction of Compound 8. Analysis of ER Ca2+ transport by human SERCA2a in HEK cells showed that only Compound 6 increased both ER Ca2+ uptake and ER Ca2+ load significantly, whereas Compound 8 had no effect on SERCA2a Ca2+ transport. This study revealed that Compound 6 exhibits promising characteristics that can improve intracellular Ca2+ dynamics by selectively enhancing SERCA2a Ca2+ uptake.
Collapse
Affiliation(s)
- Elisa Bovo
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL, 60153, USA
| | - Robyn T Rebbeck
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Osha Roopnarine
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Razvan L Cornea
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - David D Thomas
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Aleksey V Zima
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL, 60153, USA.
| |
Collapse
|
6
|
Smith CER, Grandi E. Unveiling the intricacies of intracellular Ca 2+ regulation in the heart. Biophys J 2023; 122:3019-3021. [PMID: 37478843 PMCID: PMC10432241 DOI: 10.1016/j.bpj.2023.07.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 07/07/2023] [Accepted: 07/07/2023] [Indexed: 07/23/2023] Open
Abstract
Recent studies have provided valuable insight into the key mechanisms contributing to the spatiotemporal regulation of intracellular Ca2+ release and Ca2+ signaling in the heart. In this research highlight, we focus on the latest findings published in Biophysical Journal examining the structural organization of Ca2+ handling proteins and assessing the functional aspects of intracellular Ca2+ regulation in health and the detrimental consequences of Ca2+ dysregulation in disease. These important studies pave the way for future mechanistic investigations and multiscale understanding of Ca2+ signaling in the heart.
Collapse
Affiliation(s)
- Charlotte E R Smith
- Department of Pharmacology, University of California Davis, Davis, California.
| | - Eleonora Grandi
- Department of Pharmacology, University of California Davis, Davis, California.
| |
Collapse
|
7
|
Seflova J, Habibi NR, Yap JQ, Cleary SR, Fang X, Kekenes-Huskey PM, Espinoza-Fonseca LM, Bossuyt JB, Robia SL. Fluorescence lifetime imaging microscopy reveals sodium pump dimers in live cells. J Biol Chem 2022; 298:101865. [PMID: 35339486 PMCID: PMC9048134 DOI: 10.1016/j.jbc.2022.101865] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Revised: 03/08/2022] [Accepted: 03/10/2022] [Indexed: 12/30/2022] Open
Abstract
The sodium-potassium ATPase (Na/K-ATPase, NKA) establishes ion gradients that facilitate many physiological functions including action potentials and secondary transport processes. NKA comprises a catalytic subunit (alpha) that interacts closely with an essential subunit (beta) and regulatory transmembrane micropeptides called FXYD proteins. In the heart, a key modulatory partner is the FXYD protein phospholemman (PLM, FXYD1), but the stoichiometry of the alpha-beta-PLM regulatory complex is unknown. Here, we used fluorescence lifetime imaging and spectroscopy to investigate the structure, stoichiometry, and affinity of the NKA-regulatory complex. We observed a concentration-dependent binding of the subunits of NKA-PLM regulatory complex, with avid association of the alpha subunit with the essential beta subunit as well as lower affinity alpha-alpha and alpha-PLM interactions. These data provide the first evidence that, in intact live cells, the regulatory complex is composed of two alpha subunits associated with two beta subunits, decorated with two PLM regulatory subunits. Docking and molecular dynamics (MD) simulations generated a structural model of the complex that is consistent with our experimental observations. We propose that alpha-alpha subunit interactions support conformational coupling of the catalytic subunits, which may enhance NKA turnover rate. These observations provide insight into the pathophysiology of heart failure, wherein low NKA expression may be insufficient to support formation of the complete regulatory complex with the stoichiometry (alpha-beta-PLM)2.
Collapse
Affiliation(s)
- Jaroslava Seflova
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - Nima R Habibi
- Department of Pharmacology, University of California Davis, Davis, California, USA
| | - John Q Yap
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - Sean R Cleary
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - Xuan Fang
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - Peter M Kekenes-Huskey
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA
| | - L Michel Espinoza-Fonseca
- Division of Cardiovascular Medicine, Department of Internal Medicine, Center for Arrhythmia Research, University of Michigan, Ann Arbor, Michigan, USA
| | - Julie B Bossuyt
- Department of Pharmacology, University of California Davis, Davis, California, USA.
| | - Seth L Robia
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, Illinois, USA.
| |
Collapse
|
8
|
Bovo E, Nikolaienko R, Kahn D, Cho E, Robia SL, Zima AV. Presenilin 1 is a direct regulator of the cardiac sarco/endoplasmic reticulum calcium pump. Cell Calcium 2021; 99:102468. [PMID: 34517214 PMCID: PMC8541915 DOI: 10.1016/j.ceca.2021.102468] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 08/30/2021] [Accepted: 09/01/2021] [Indexed: 10/20/2022]
Abstract
The gamma secretase catalytic subunit presenilin 1 (PS1) is expressed in the endoplasmic reticulum (ER) of neurons, where it regulates Ca2+ signaling. PS1 is also expressed in heart, but its role in regulation of cardiac Ca2+ transport remains unknown. Since the type 2 sarco/endoplasmic reticulum Ca2+ ATPase (SERCA2a) plays a central role in cardiac Ca2+ homeostasis, we studied whether PS1 regulates the cardiac SERCA2a function. The experiments were conducted in an inducible human SERCA2a stable T-Rex-293 cell line transfected with fluorescently labeled PS1 and the ER Ca2+ sensor R-CEPIA1er. Confocal imaging showed that that PS1 is localized predominantly in the ER membrane. Fluorescent resonance energy transfer (FRET) experiments in HEK293 cells transfected with fluorescently labeled SERCA2a and PS1 revealed that the two proteins directly interact with a 1:1 stoichiometry. The functional significance of this interaction was investigated in a heterologous cellular environment using a novel approach to directly measure ER Ca2+ dynamics. Measurements of SERCA2a-mediated Ca2+ transport showed that PS1 enhanced Ca2+ uptake at low ER Ca2+ loads (<0.15 mM) and reduced uptake at high loads (>0.35 mM). The results of this study revealed that PS1 could act as an important regulator of the cardiac Ca2+ pump function with a complex stimulatory/inhibitory profile.
Collapse
Affiliation(s)
- Elisa Bovo
- Department of Cell and Molecular Physiology, Loyola University Chicago, IL, USA.
| | - Roman Nikolaienko
- Department of Cell and Molecular Physiology, Loyola University Chicago, IL, USA
| | - Daniel Kahn
- Department of Cell and Molecular Physiology, Loyola University Chicago, IL, USA
| | - Ellen Cho
- Department of Cell and Molecular Physiology, Loyola University Chicago, IL, USA
| | - Seth L Robia
- Department of Cell and Molecular Physiology, Loyola University Chicago, IL, USA
| | - Aleksey V Zima
- Department of Cell and Molecular Physiology, Loyola University Chicago, IL, USA
| |
Collapse
|
9
|
Serrano J, Seflova J, Park J, Pribadi M, Sanematsu K, Shigemura N, Serna V, Yi F, Mari A, Procko E, Pratley RE, Robia SL, Kyriazis GA. The Ile191Val is a partial loss-of-function variant of the TAS1R2 sweet-taste receptor and is associated with reduced glucose excursions in humans. Mol Metab 2021; 54:101339. [PMID: 34509698 PMCID: PMC8476773 DOI: 10.1016/j.molmet.2021.101339] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 08/31/2021] [Accepted: 09/02/2021] [Indexed: 10/29/2022] Open
Abstract
OBJECTIVE Sweet taste receptors (STR) are expressed in the gut and other extra-oral tissues, suggesting that STR-mediated nutrient sensing may contribute to human physiology beyond taste. A common variant (Ile191Val) in the TAS1R2 gene of STR is associated with nutritional and metabolic outcomes independent of changes in taste perception. It is unclear whether this polymorphism directly alters STR function and how it may contribute to metabolic regulation. METHODS We implemented a combination of in vitro biochemical approaches to decipher the effects of TAS1R2 polymorphism on STR function. Then, as proof-of-concept, we assessed its effects on glucose homeostasis in apparently healthy lean participants. RESULTS The Ile191Val variant causes a partial loss of function of TAS1R2 through reduced receptor availability in the plasma membrane. Val minor allele carriers have reduced glucose excursions during an OGTT, mirroring effects previously seen in mice with genetic loss of function of TAS1R2. These effects were not due to differences in beta-cell function or insulin sensitivity. CONCLUSIONS Our pilot studies on a common TAS1R2 polymorphism suggest that STR sensory function in peripheral tissues, such as the intestine, may contribute to the regulation of metabolic control in humans.
Collapse
Affiliation(s)
- Joan Serrano
- Department of Biological Chemistry & Pharmacology, College of Medicine, The Ohio State University, Columbus, OH, USA
| | - Jaroslava Seflova
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL, 60153, USA
| | - Jihye Park
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Marsha Pribadi
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL, 60153, USA
| | - Keisuke Sanematsu
- Section of Oral Neuroscience, Graduate School of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan
| | - Noriatsu Shigemura
- Section of Oral Neuroscience, Graduate School of Dental Science, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan
| | - Vanida Serna
- Department of Biological Chemistry & Pharmacology, College of Medicine, The Ohio State University, Columbus, OH, USA
| | - Fanchao Yi
- AdventHealth Translational Research Institute, Orlando, FL, 32804, USA
| | - Andrea Mari
- Institute of Neuroscience, National Research Council, Padova, Italy
| | - Erik Procko
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Richard E Pratley
- AdventHealth Translational Research Institute, Orlando, FL, 32804, USA
| | - Seth L Robia
- Department of Cell and Molecular Physiology, Loyola University Chicago, Maywood, IL, 60153, USA
| | - George A Kyriazis
- Department of Biological Chemistry & Pharmacology, College of Medicine, The Ohio State University, Columbus, OH, USA.
| |
Collapse
|
10
|
Galindo-Hernandez O, Leija-Montoya AG, Romero-Garcia T, Vazquez-Jimenez JG. Palmitic acid decreases cell migration by increasing RGS2 expression and decreasing SERCA expression. Genet Mol Biol 2021; 44:e20200279. [PMID: 33729330 PMCID: PMC7967171 DOI: 10.1590/1678-4685-gmb-2020-0279] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 01/18/2021] [Indexed: 12/13/2022] Open
Abstract
Palmitic acid, the main saturated fatty acid, is related with a wide range of
metabolic disorders such as obesity, type 2 diabetes and heart disease. It is
known that palmitic acid disturbs the expression of some important proteins for
cell homeostasis such as SERCA and RGS2, however, the role of this lipid at the
molecular level in these disorders is not completely elucidated. Thus, our aim
was to determinate the effect of palmitic acid in a relevant cell process as it
is cell migration and the participation of SERCA and RGS2 in this response. We
found that palmitic acid reduces cell migration (determined by the Boyden
chamber method) in an epithelial cell line (HEK293) and this effect is modulated
by SERCA and RGS2 differential protein expression (measured by western blot).
Also, overexpression of individual proteins, RGS2 and SERCA, produced a decrease
and an increase on cell migration, respectively. Taken together, these data
suggest that the expression of regulatory proteins is affected by high
concentrations of saturated fatty acids and in consequence cell migration is
diminished in epithelial cells.
Collapse
Affiliation(s)
- Octavio Galindo-Hernandez
- Autonomous University of Baja California, Laboratory of Biochemistry, School of Medicine, Campus Mexicali, BC, Mexico
| | - Ana Gabriela Leija-Montoya
- Autonomous University of Baja California, Laboratory of Biochemistry, School of Medicine, Campus Mexicali, BC, Mexico
| | - Tatiana Romero-Garcia
- Autonomous University of Baja California, Laboratory of Biochemistry, Sports School, Campus Mexicali, BC, Mexico
| | - Jose Gustavo Vazquez-Jimenez
- Autonomous University of Baja California, Laboratory of Molecular Pathogenesis, School of Medicine, Campus Mexicali, BC, Mexico
| |
Collapse
|