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Contreras RG, Torres-Carrillo A, Flores-Maldonado C, Shoshani L, Ponce A. Na +/K +-ATPase: More than an Electrogenic Pump. Int J Mol Sci 2024; 25:6122. [PMID: 38892309 PMCID: PMC11172918 DOI: 10.3390/ijms25116122] [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: 03/26/2024] [Revised: 05/20/2024] [Accepted: 05/23/2024] [Indexed: 06/21/2024] Open
Abstract
The sodium pump, or Na+/K+-ATPase (NKA), is an essential enzyme found in the plasma membrane of all animal cells. Its primary role is to transport sodium (Na+) and potassium (K+) ions across the cell membrane, using energy from ATP hydrolysis. This transport creates and maintains an electrochemical gradient, which is crucial for various cellular processes, including cell volume regulation, electrical excitability, and secondary active transport. Although the role of NKA as a pump was discovered and demonstrated several decades ago, it remains the subject of intense research. Current studies aim to delve deeper into several aspects of this molecular entity, such as describing its structure and mode of operation in atomic detail, understanding its molecular and functional diversity, and examining the consequences of its malfunction due to structural alterations. Additionally, researchers are investigating the effects of various substances that amplify or decrease its pumping activity. Beyond its role as a pump, growing evidence indicates that in various cell types, NKA also functions as a receptor for cardiac glycosides like ouabain. This receptor activity triggers the activation of various signaling pathways, producing significant morphological and physiological effects. In this report, we present the results of a comprehensive review of the most outstanding studies of the past five years. We highlight the progress made regarding this new concept of NKA and the various cardiac glycosides that influence it. Furthermore, we emphasize NKA's role in epithelial physiology, particularly its function as a receptor for cardiac glycosides that trigger intracellular signals regulating cell-cell contacts, proliferation, differentiation, and adhesion. We also analyze the role of NKA β-subunits as cell adhesion molecules in glia and epithelial cells.
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Affiliation(s)
| | | | | | | | - Arturo Ponce
- Department of Physiology, Biophysics and Neurosciences, CINVESTAV-IPN, Mexico City 07360, Mexico; (R.G.C.); (A.T.-C.); (C.F.-M.); (L.S.)
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2
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Vieira TCRG, Barros CA, Domingues R, Outeiro TF. PrP meets alpha-synuclein: Molecular mechanisms and implications for disease. J Neurochem 2023. [PMID: 37855859 DOI: 10.1111/jnc.15992] [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: 07/10/2023] [Revised: 09/19/2023] [Accepted: 10/01/2023] [Indexed: 10/20/2023]
Abstract
The discovery of prions has challenged dogmas and has revolutionized our understanding of protein-misfolding diseases. The concept of self-propagation via protein conformational changes, originally discovered for the prion protein (PrP), also applies to other proteins that exhibit similar behavior, such as alpha-synuclein (aSyn), a central player in Parkinson's disease and in other synucleinopathies. aSyn pathology appears to spread from one cell to another during disease progression, and involves the misfolding and aggregation of aSyn. How the transfer of aSyn between cells occurs is still being studied, but one important hypothesis involves receptor-mediated transport. Interestingly, recent studies indicate that the cellular prion protein (PrPC ) may play a crucial role in this process. PrPC has been shown to act as a receptor/sensor for protein aggregates in different neurodegenerative disorders, including Alzheimer's disease and amyotrophic lateral sclerosis. Here, we provide a comprehensive overview of the current state of knowledge regarding the interaction between aSyn and PrPC and discuss its role in synucleinopathies. We examine the properties of PrP and aSyn, including their structure, function, and aggregation. Additionally, we discuss the current understanding of PrPC 's role as a receptor/sensor for aSyn aggregates and identify remaining unanswered questions in this area of research. Ultimately, we posit that exploring the interaction between aSyn and PrPC may offer potential treatment options for synucleinopathies.
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Affiliation(s)
- Tuane C R G Vieira
- Institute of Medical Biochemistry Leopoldo de Meis and National Institute of Science and Technology for Structural Biology and Bioimaging, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Caroline A Barros
- Institute of Medical Biochemistry Leopoldo de Meis and National Institute of Science and Technology for Structural Biology and Bioimaging, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Renato Domingues
- Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
| | - Tiago Fleming Outeiro
- Department of Experimental Neurodegeneration, Center for Biostructural Imaging of Neurodegeneration, University Medical Center Göttingen, Göttingen, Germany
- Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
- Faculty of Medical Sciences, Translational and Clinical Research Institute, Newcastle University, Newcastle Upon Tyne, UK
- Scientific Employee with an Honorary Contract at Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Göttingen, Germany
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3
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Moustafa A, Hashemi S, Brar G, Grigull J, Ng SHS, Williams D, Schmitt-Ulms G, McDermott JC. The MEF2A transcription factor interactome in cardiomyocytes. Cell Death Dis 2023; 14:240. [PMID: 37019881 PMCID: PMC10076289 DOI: 10.1038/s41419-023-05665-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 12/02/2022] [Accepted: 02/08/2023] [Indexed: 04/07/2023]
Abstract
Transcriptional regulators encoded by the Myocyte Enhancer Factor 2 (MEF2) gene family play a fundamental role in cardiac development, homeostasis and pathology. Previous studies indicate that MEF2A protein-protein interactions serve as a network hub in several cardiomyocyte cellular processes. Based on the idea that interactions with regulatory protein partners underly the diverse roles of MEF2A in cardiomyocyte gene expression, we undertook a systematic unbiased screen of the MEF2A protein interactome in primary cardiomyocytes using an affinity purification-based quantitative mass spectrometry approach. Bioinformatic processing of the MEF2A interactome revealed protein networks involved in the regulation of programmed cell death, inflammatory responses, actin dynamics and stress signaling in primary cardiomyocytes. Further biochemical and functional confirmation of specific protein-protein interactions documented a dynamic interaction between MEF2A and STAT3 proteins. Integration of transcriptome level data from MEF2A and STAT3-depleted cardiomyocytes reveals that the balance between MEF2A and STAT3 activity exerts a level of executive control over the inflammatory response and cardiomyocyte cell survival and experimentally ameliorates Phenylephrine induced cardiomyocyte hypertrophy. Lastly, we identified several MEF2A/STAT3 co-regulated genes, including the MMP9 gene. Herein, we document the cardiomyocyte MEF2A interactome, which furthers our understanding of protein networks involved in the hierarchical control of normal and pathophysiological cardiomyocyte gene expression in the mammalian heart.
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Affiliation(s)
- Amira Moustafa
- Department of Biology, York University, Toronto, ON, M3J 1P3, Canada
- Muscle Health Research Centre (MHRC), York University, Toronto, ON, M3J 1P3, Canada
- Centre for Research in Biomolecular Interactions (CRBI), York University, Toronto, ON, M3J 1P3, Canada
| | - Sara Hashemi
- Analytical Sciences, Sanofi, Toronto, ON, M2R 3T4, Canada
- Seneca College, School of Health Sciences, King City, ON, L7B 1B3, Canada
| | - Gurnoor Brar
- Department of Biology, York University, Toronto, ON, M3J 1P3, Canada
- Muscle Health Research Centre (MHRC), York University, Toronto, ON, M3J 1P3, Canada
- Centre for Research in Biomolecular Interactions (CRBI), York University, Toronto, ON, M3J 1P3, Canada
| | - Jörg Grigull
- Department of Mathematics and Statistics, York University, Toronto, ON, M3J1P3, Canada
| | - Siemon H S Ng
- Analytical Sciences, Sanofi, Toronto, ON, M2R 3T4, Canada
- Analytical Development, Notch Therapeutics, Toronto, ON, M5G 1M1, Canada
| | - Declan Williams
- Tanz Centre for Research in Neurodegenerative Diseases, and Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, M5T 0S8, Canada
| | - Gerold Schmitt-Ulms
- Tanz Centre for Research in Neurodegenerative Diseases, and Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, M5T 0S8, Canada
| | - John C McDermott
- Department of Biology, York University, Toronto, ON, M3J 1P3, Canada.
- Muscle Health Research Centre (MHRC), York University, Toronto, ON, M3J 1P3, Canada.
- Centre for Research in Biomolecular Interactions (CRBI), York University, Toronto, ON, M3J 1P3, Canada.
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4
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Identification of a Cardiac Glycoside Exhibiting Favorable Brain Bioavailability and Potency for Reducing Levels of the Cellular Prion Protein. Int J Mol Sci 2022; 23:ijms232314823. [PMID: 36499150 PMCID: PMC9736291 DOI: 10.3390/ijms232314823] [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: 10/17/2022] [Revised: 11/19/2022] [Accepted: 11/23/2022] [Indexed: 12/03/2022] Open
Abstract
Several strands of investigation have established that a reduction in the levels of the cellular prion protein (PrPC) is a promising avenue for the treatment of prion diseases. We recently described an indirect approach for reducing PrPC levels that targets Na,K-ATPases (NKAs) with cardiac glycosides (CGs), causing cells to respond with the degradation of these pumps and nearby molecules, including PrPC. Because the therapeutic window of widely used CGs is narrow and their brain bioavailability is low, we set out to identify a CG with improved pharmacological properties for this indication. Starting with the CG known as oleandrin, we combined in silico modeling of CG binding poses within human NKA folds, CG structure-activity relationship (SAR) data, and predicted blood-brain barrier (BBB) penetrance scores to identify CG derivatives with improved characteristics. Focusing on C4'-dehydro-oleandrin as a chemically accessible shortlisted CG derivative, we show that it reaches four times higher levels in the brain than in the heart one day after subcutaneous administration, exhibits promising pharmacological properties, and suppresses steady-state PrPC levels by 84% in immortalized human cells that have been differentiated to acquire neural or astrocytic characteristics. Finally, we validate that the mechanism of action of this approach for reducing cell surface PrPC levels requires C4'-dehydro-oleandrin to engage with its cognate binding pocket within the NKA α subunit. The improved brain bioavailability of C4'-dehydro-oleandrin, combined with its relatively low toxicity, make this compound an attractive lead for brain CG indications and recommends its further exploration for the treatment of prion diseases.
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Mercer RCC, Harris DA. Mechanisms of prion-induced toxicity. Cell Tissue Res 2022; 392:81-96. [PMID: 36070155 DOI: 10.1007/s00441-022-03683-0] [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: 06/08/2022] [Accepted: 08/30/2022] [Indexed: 11/02/2022]
Abstract
Prion diseases are devastating neurodegenerative diseases caused by the structural conversion of the normally benign prion protein (PrPC) to an infectious, disease-associated, conformer, PrPSc. After decades of intense research, much is known about the self-templated prion conversion process, a phenomenon which is now understood to be operative in other more common neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. In this review, we provide the current state of knowledge concerning a relatively poorly understood aspect of prion diseases: mechanisms of neurotoxicity. We provide an overview of proposed functions of PrPC and its interactions with other extracellular proteins in the central nervous system, in vivo and in vitro models used to delineate signaling events downstream of prion propagation, the application of omics technologies, and the emerging appreciation of the role played by non-neuronal cell types in pathogenesis.
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Affiliation(s)
- Robert C C Mercer
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA
| | - David A Harris
- Department of Biochemistry, Boston University School of Medicine, Boston, MA, USA.
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6
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Mehrabian M, Wang X, Eid S, Yan BQ, Grinberg M, Siegner M, Sackmann C, Sulman M, Zhao W, Williams D, Schmitt-Ulms G. Cardiac glycoside-mediated turnover of Na, K-ATPases as a rational approach to reducing cell surface levels of the cellular prion protein. PLoS One 2022; 17:e0270915. [PMID: 35776750 PMCID: PMC9249225 DOI: 10.1371/journal.pone.0270915] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Accepted: 06/17/2022] [Indexed: 01/16/2023] Open
Abstract
It is widely anticipated that a reduction of brain levels of the cellular prion protein (PrPC) can prolong survival in a group of neurodegenerative diseases known as prion diseases. To date, efforts to decrease steady-state PrPC levels by targeting this protein directly with small molecule drug-like compounds have largely been unsuccessful. Recently, we reported Na,K-ATPases to reside in immediate proximity to PrPC in the brain, unlocking an opportunity for an indirect PrPC targeting approach that capitalizes on the availability of potent cardiac glycosides (CGs). Here, we report that exposure of human co-cultures of neurons and astrocytes to non-toxic nanomolar levels of CGs causes profound reductions in PrPC levels. The mechanism of action underpinning this outcome relies primarily on a subset of CGs engaging the ATP1A1 isoform, one of three α subunits of Na,K-ATPases expressed in brain cells. Upon CG docking to ATP1A1, the ligand receptor complex, and PrPC along with it, is internalized by the cell. Subsequently, PrPC is channeled to the lysosomal compartment where it is digested in a manner that can be rescued by silencing the cysteine protease cathepsin B. These data signify that the repurposing of CGs may be beneficial for the treatment of prion disorders.
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Affiliation(s)
- Mohadeseh Mehrabian
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Krembil Discovery Centre, Toronto, Ontario, Canada
- Department of Laboratory Medicine & Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Xinzhu Wang
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Krembil Discovery Centre, Toronto, Ontario, Canada
- Department of Laboratory Medicine & Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Shehab Eid
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Krembil Discovery Centre, Toronto, Ontario, Canada
- Department of Laboratory Medicine & Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Bei Qi Yan
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Krembil Discovery Centre, Toronto, Ontario, Canada
- Department of Laboratory Medicine & Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Mark Grinberg
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Krembil Discovery Centre, Toronto, Ontario, Canada
| | - Murdock Siegner
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Krembil Discovery Centre, Toronto, Ontario, Canada
- Department of Laboratory Medicine & Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Christopher Sackmann
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Krembil Discovery Centre, Toronto, Ontario, Canada
| | - Muhammad Sulman
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Krembil Discovery Centre, Toronto, Ontario, Canada
| | - Wenda Zhao
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Krembil Discovery Centre, Toronto, Ontario, Canada
- Department of Laboratory Medicine & Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Declan Williams
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Krembil Discovery Centre, Toronto, Ontario, Canada
| | - Gerold Schmitt-Ulms
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Krembil Discovery Centre, Toronto, Ontario, Canada
- Department of Laboratory Medicine & Pathobiology, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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7
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Arshad H, Watts JC. Genetically engineered cellular models of prion propagation. Cell Tissue Res 2022; 392:63-80. [PMID: 35581386 DOI: 10.1007/s00441-022-03630-z] [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: 02/16/2022] [Accepted: 04/26/2022] [Indexed: 11/02/2022]
Abstract
For over three decades, cultured cells have been a useful tool for dissecting the molecular details of prion replication and the identification of candidate therapeutics for prion disease. A major issue limiting the translatability of these studies has been the inability to reliably propagate disease-relevant, non-mouse strains of prions in cells relevant to prion pathogenesis. In recent years, fueled by advances in gene editing technology, it has become possible to propagate prions from hamsters, cervids, and sheep in immortalized cell lines originating from the central nervous system. In particular, the use of CRISPR-Cas9-mediated gene editing to generate versions of prion-permissive cell lines that lack endogenous PrP expression has provided a blank canvas upon which re-expression of PrP leads to species-matched susceptibility to prion infection. When coupled with the ability to propagate prions in cells or organoids derived from stem cells, these next-generation cellular models should provide an ideal paradigm for identifying small molecules and other biological therapeutics capable of interfering with prion replication in animal and human prion disorders. In this review, we summarize recent advances that have widened the spectrum of prion strains that can be propagated in cultured cells and cutting-edge tissue-based models.
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Affiliation(s)
- Hamza Arshad
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Krembil Discovery Tower Rm. 4KD481, 60 Leonard Ave, Toronto, ON, M5T 0S8, Canada.,Department of Biochemistry, University of Toronto, 1 King's College Circle, Medical Sciences Building Rm. 5207, Toronto, ON, M5S 1A8, Canada
| | - Joel C Watts
- Tanz Centre for Research in Neurodegenerative Diseases, University of Toronto, Krembil Discovery Tower Rm. 4KD481, 60 Leonard Ave, Toronto, ON, M5T 0S8, Canada. .,Department of Biochemistry, University of Toronto, 1 King's College Circle, Medical Sciences Building Rm. 5207, Toronto, ON, M5S 1A8, Canada.
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