1
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Smith-Cortinez N, Heegsma J, Podunavac M, Zakarian A, Cardenas JC, Faber KN. Novel Inositol 1,4,5-Trisphosphate Receptor Inhibitor Antagonizes Hepatic Stellate Cell Activation: A Potential Drug to Treat Liver Fibrosis. Cells 2024; 13:765. [PMID: 38727301 PMCID: PMC11083487 DOI: 10.3390/cells13090765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 04/18/2024] [Accepted: 04/23/2024] [Indexed: 05/13/2024] Open
Abstract
Liver fibrosis, characterized by excessive extracellular matrix (ECM) deposition, can progress to cirrhosis and increases the risk of liver cancer. Hepatic stellate cells (HSCs) play a pivotal role in fibrosis progression, transitioning from a quiescent to activated state upon liver injury, wherein they proliferate, migrate, and produce ECM. Calcium signaling, involving the inositol 1,4,5-trisphosphate receptor (IP3R), regulates HSC activation. This study investigated the efficacy of a novel IP3R inhibitor, desmethylxestospongin B (dmXeB), in preventing HSC activation. Freshly isolated rat HSCs were activated in vitro in the presence of varying dmXeB concentrations. The dmXeB effectively inhibited HSC proliferation, migration, and expression of fibrosis markers without toxicity to the primary rat hepatocytes or human liver organoids. Furthermore, dmXeB preserved the quiescent phenotype of HSCs marked by retained vitamin A storage. Mechanistically, dmXeB suppressed mitochondrial respiration in activated HSCs while enhancing glycolytic activity. Notably, methyl pyruvate, dimethyl α-ketoglutarate, and nucleoside supplementation all individually restored HSC proliferation despite dmXeB treatment. Overall, dmXeB demonstrates promising anti-fibrotic effects by inhibiting HSC activation via IP3R antagonism without adverse effects on other liver cells. These findings highlight dmXeB as a potential therapeutic agent for liver fibrosis treatment, offering a targeted approach to mitigate liver fibrosis progression and its associated complications.
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Affiliation(s)
- Natalia Smith-Cortinez
- Department of Gastroenterology and Hepatology, University of Groningen, University Medical Center Groningen (UMCG), 9713 GZ Groningen, The Netherlands
| | - Janette Heegsma
- Department of Gastroenterology and Hepatology, University of Groningen, University Medical Center Groningen (UMCG), 9713 GZ Groningen, The Netherlands
| | - Masa Podunavac
- Department of Chemistry and Biochemistry, University of California, Oakland, CA 94607, USA
| | - Armen Zakarian
- Department of Chemistry and Biochemistry, University of California, Oakland, CA 94607, USA
| | - J. César Cardenas
- Department of Chemistry and Biochemistry, University of California, Oakland, CA 94607, USA
- Center for Integrative Biology, Universidad Mayor, Santiago 7510041, Chile
- Buck Institute for Research on Aging, Novato, CA 94945, USA
| | - Klaas Nico Faber
- Department of Gastroenterology and Hepatology, University of Groningen, University Medical Center Groningen (UMCG), 9713 GZ Groningen, The Netherlands
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2
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Kjær C, Palasca O, Barzaghi G, Bak LK, Durhuus RKJ, Jakobsen E, Pedersen L, Bartels ED, Woldbye DPD, Pinborg LH, Jensen LJ. Differential Expression of the β3 Subunit of Voltage-Gated Ca 2+ Channel in Mesial Temporal Lobe Epilepsy. Mol Neurobiol 2023; 60:5755-5769. [PMID: 37341859 PMCID: PMC10471638 DOI: 10.1007/s12035-023-03426-4] [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: 12/21/2022] [Accepted: 06/05/2023] [Indexed: 06/22/2023]
Abstract
The purpose of this study was to identify and validate new putative lead drug targets in drug-resistant mesial temporal lobe epilepsy (mTLE) starting from differentially expressed genes (DEGs) previously identified in mTLE in humans by transcriptome analysis. We identified consensus DEGs among two independent mTLE transcriptome datasets and assigned them status as "lead target" if they (1) were involved in neuronal excitability, (2) were new in mTLE, and (3) were druggable. For this, we created a consensus DEG network in STRING and annotated it with information from the DISEASES database and the Target Central Resource Database (TCRD). Next, we attempted to validate lead targets using qPCR, immunohistochemistry, and Western blot on hippocampal and temporal lobe neocortical tissue from mTLE patients and non-epilepsy controls, respectively. Here we created a robust, unbiased list of 113 consensus DEGs starting from two lists of 3040 and 5523 mTLE significant DEGs, respectively, and identified five lead targets. Next, we showed that CACNB3, a voltage-gated Ca2+ channel subunit, was significantly regulated in mTLE at both mRNA and protein level. Considering the key role of Ca2+ currents in regulating neuronal excitability, this suggested a role for CACNB3 in seizure generation. This is the first time changes in CACNB3 expression have been associated with drug-resistant epilepsy in humans, and since efficient therapeutic strategies for the treatment of drug-resistant mTLE are lacking, our finding might represent a step toward designing such new treatment strategies.
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Affiliation(s)
- Christina Kjær
- Biomedical Laboratory Science, Department of Technology, Faculty of Health and Technology, University College Copenhagen, Sigurdsgade 26, 1St, 2200 Copenhagen, Denmark
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Oana Palasca
- Disease Systems Biology Program, Faculty of Health and Medical Sciences, Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark
| | - Guido Barzaghi
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
- European Molecular Biology Laboratory (EMBL), Genome Biology Unit, Heidelberg, Germany
- Faculty of Biosciences, Collaboration for Joint PhD Degree Between EMBL and Heidelberg University, Heidelberg, Germany
| | - Lasse K. Bak
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
- Dept. of Clinical Biochemistry, 2600 RigshospitaletCopenhagen, Denmark
| | - Rúna K. J. Durhuus
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
- Specific Pharma A/S, Borgmester Christiansens Gade 40, 2450 Copenhagen, SV Denmark
| | - Emil Jakobsen
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences, University of Copenhagen, 2100 Copenhagen, Denmark
- Takeda Pharma A/S, Delta Park 45, 2665 Vallensbaek Strand, Denmark
| | - Louise Pedersen
- Biomedical Laboratory Science, Department of Technology, Faculty of Health and Technology, University College Copenhagen, Sigurdsgade 26, 1St, 2200 Copenhagen, Denmark
- Dept. of Clinical Biochemistry, 2600 RigshospitaletCopenhagen, Denmark
| | - Emil D. Bartels
- Dept. of Clinical Biochemistry, 2600 RigshospitaletCopenhagen, Denmark
- Department of Clinical Medicine, University of Copenhagen, Copenhagen, Denmark
| | - David P. D. Woldbye
- Department of Neuroscience, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Lars H. Pinborg
- Epilepsy Clinic & Neurobiology Research Unit, Copenhagen University Hospital, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Lars Juhl Jensen
- Disease Systems Biology Program, Faculty of Health and Medical Sciences, Novo Nordisk Foundation Center for Protein Research, University of Copenhagen, Copenhagen, Denmark
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3
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Woo MS, Ufer F, Sonner JK, Belkacemi A, Tintelnot J, Sáez PJ, Krieg PF, Mayer C, Binkle-Ladisch L, Engler JB, Bauer S, Kursawe N, Vieira V, Mannebach S, Freichel M, Flockerzi V, Vargas P, Friese MA. Calcium channel β3 subunit regulates ATP-dependent migration of dendritic cells. SCIENCE ADVANCES 2023; 9:eadh1653. [PMID: 37729408 PMCID: PMC10511199 DOI: 10.1126/sciadv.adh1653] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 08/18/2023] [Indexed: 09/22/2023]
Abstract
Migratory dendritic cells (migDCs) continuously patrol tissues and are activated by injury and inflammation. Extracellular adenosine triphosphate (ATP) is released by damaged cells or actively secreted during inflammation and increases migDC motility. However, the underlying molecular mechanisms by which ATP accelerates migDC migration is not understood. Here, we show that migDCs can be distinguished from other DC subsets and immune cells by their expression of the voltage-gated calcium channel subunit β3 (Cavβ3; CACNB3), which exclusively facilitates ATP-dependent migration in vitro and during tissue damage in vivo. By contrast, CACNB3 does not regulate lipopolysaccharide-dependent migration. Mechanistically, CACNB3 regulates ATP-dependent inositol 1,4,5-trisphophate receptor-controlled calcium release from the endoplasmic reticulum. This, in turn, is required for ATP-mediated suppression of adhesion molecules, their detachment, and initiation of migDC migration. Thus, Cacnb3-deficient migDCs have an impaired migration after ATP exposure. In summary, we identified CACNB3 as a master regulator of ATP-dependent migDC migration that controls tissue-specific immunological responses during injury and inflammation.
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Affiliation(s)
- Marcel S Woo
- Institute of Neuroimmunology and Multiple Sclerosis, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Friederike Ufer
- Institute of Neuroimmunology and Multiple Sclerosis, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Jana K Sonner
- Institute of Neuroimmunology and Multiple Sclerosis, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Anouar Belkacemi
- Institute of Pharmacology, Heidelberg University, 69120 Heidelberg, Germany
- Experimental and Clinical Pharmacology and Toxicology, Saarland University, 66421 Homburg, Germany
| | - Joseph Tintelnot
- Institute of Neuroimmunology and Multiple Sclerosis, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Pablo J Sáez
- Institut Curie and Institut Pierre-Gilles de Gennes, PSL Research University, CNRS, UMR 144, F-75005, Paris, France
- Cell Communication and Migration Laboratory, Institute of Biochemistry and Molecular Cell Biology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Paula F Krieg
- Institute of Neuroimmunology and Multiple Sclerosis, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Christina Mayer
- Institute of Neuroimmunology and Multiple Sclerosis, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Lars Binkle-Ladisch
- Institute of Neuroimmunology and Multiple Sclerosis, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Jan Broder Engler
- Institute of Neuroimmunology and Multiple Sclerosis, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Simone Bauer
- Institute of Neuroimmunology and Multiple Sclerosis, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Nina Kursawe
- Institute of Neuroimmunology and Multiple Sclerosis, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Vanessa Vieira
- Institute of Neuroimmunology and Multiple Sclerosis, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Stefanie Mannebach
- Experimental and Clinical Pharmacology and Toxicology, Saarland University, 66421 Homburg, Germany
| | - Marc Freichel
- Institute of Pharmacology, Heidelberg University, 69120 Heidelberg, Germany
- DZHK (German Centre for Cardiovascular Research), partner site Heidelberg/Mannheim, 69120 Heidelberg, Germany
| | - Veit Flockerzi
- Experimental and Clinical Pharmacology and Toxicology, Saarland University, 66421 Homburg, Germany
| | - Pablo Vargas
- Institut Curie and Institut Pierre-Gilles de Gennes, PSL Research University, CNRS, UMR 144, F-75005, Paris, France
- Université Paris Cité, INSERM UMR-S1151, CNRS UMR-S8253, Institut Necker Enfants Malades, Paris, France
| | - Manuel A Friese
- Institute of Neuroimmunology and Multiple Sclerosis, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
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4
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Vergnol A, Traoré M, Pietri-Rouxel F, Falcone S. New Insights in CaVβ Subunits: Role in the Regulation of Gene Expression and Cellular Homeostasis. Front Cell Dev Biol 2022; 10:880441. [PMID: 35465309 PMCID: PMC9019481 DOI: 10.3389/fcell.2022.880441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Accepted: 03/16/2022] [Indexed: 11/23/2022] Open
Abstract
The voltage-gated calcium channels (CaVs or VGCCs) are fundamental regulators of intracellular calcium homeostasis. When electrical activity induces their activation, the influx of calcium that they mediate or their interaction with intracellular players leads to changes in intracellular Ca2+ levels which regulate many processes such as contraction, secretion and gene expression, depending on the cell type. The essential component of the pore channel is the CaVα1 subunit. However, the fine-tuning of Ca2+-dependent signals is guaranteed by the modulatory role of the auxiliary subunits β, α2δ, and γ of the CaVs. In particular, four different CaVβ proteins (CaVβ1, CaVβ2, CaVβ3, and CaVβ4) are encoded by four different genes in mammalians, each of them displaying several splice variants. Some of these isoforms have been described in regulating CaVα1 docking and stability at the membrane and controlling the channel complex’s conformational changes. In addition, emerging evidences have highlighted other properties of the CaVβ subunits, independently of α1 and non-correlated to its channel or voltage sensing functions. This review summarizes the recent findings reporting novel roles of the auxiliary CaVβ subunits and in particular their direct or indirect implication in regulating gene expression in different cellular contexts.
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5
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IP3-dependent Ca2+ signals are tightly controlled by Cavβ3, but not by Cavβ1, 2 and 4. Cell Calcium 2022; 104:102573. [DOI: 10.1016/j.ceca.2022.102573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 02/17/2022] [Accepted: 03/15/2022] [Indexed: 11/18/2022]
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6
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Heiman P, Mohsen AW, Karunanidhi A, St Croix C, Watkins S, Koppes E, Haas R, Vockley J, Ghaloul-Gonzalez L. Mitochondrial dysfunction associated with TANGO2 deficiency. Sci Rep 2022; 12:3045. [PMID: 35197517 PMCID: PMC8866466 DOI: 10.1038/s41598-022-07076-9] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 02/07/2022] [Indexed: 11/18/2022] Open
Abstract
Transport and Golgi Organization protein 2 Homolog (TANGO2)-related disease is an autosomal recessive disorder caused by mutations in the TANGO2 gene. Symptoms typically manifest in early childhood and include developmental delay, stress-induced episodic rhabdomyolysis, and cardiac arrhythmias, along with severe metabolic crises including hypoglycemia, lactic acidosis, and hyperammonemia. Severity varies among and within families. Previous studies have reported contradictory evidence of mitochondrial dysfunction. Since the clinical symptoms and metabolic abnormalities are suggestive of a broad dysfunction of mitochondrial energy metabolism, we undertook a broad examination of mitochondrial bioenergetics in TANGO2 deficient patients utilizing skin fibroblasts derived from three patients exhibiting TANGO2-related disease. Functional studies revealed that TANGO2 protein was present in mitochondrial extracts of control cells but not patient cells. Superoxide production was increased in patient cells, while oxygen consumption rate, particularly under stress, along with relative ATP levels and β-oxidation of oleate were reduced. Our findings suggest that mitochondrial function should be assessed and monitored in all patients with TANGO2 mutation as targeted treatment of the energy dysfunction could improve outcome in this condition.
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Affiliation(s)
- Paige Heiman
- Division of Genetic and Genomic Medicine, Department of Pediatrics, University of Pittsburgh, Pittsburgh, PA, USA
| | - Al-Walid Mohsen
- Division of Genetic and Genomic Medicine, Department of Pediatrics, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Anuradha Karunanidhi
- Division of Genetic and Genomic Medicine, Department of Pediatrics, University of Pittsburgh, Pittsburgh, PA, USA
| | - Claudette St Croix
- Department of Cell Biology, Center for Biologic Imaging, University of Pittsburgh, Pittsburgh, PA, USA
| | - Simon Watkins
- Department of Cell Biology, Center for Biologic Imaging, University of Pittsburgh, Pittsburgh, PA, USA
| | - Erik Koppes
- Division of Genetic and Genomic Medicine, Department of Pediatrics, University of Pittsburgh, Pittsburgh, PA, USA
| | - Richard Haas
- Division of Pediatric Neurology, Departments of Neurosciences and Pediatrics, University of California San Diego and Rady Children's Hospital-San Diego, San Diego, CA, USA
| | - Jerry Vockley
- Division of Genetic and Genomic Medicine, Department of Pediatrics, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA
| | - Lina Ghaloul-Gonzalez
- Division of Genetic and Genomic Medicine, Department of Pediatrics, University of Pittsburgh, Pittsburgh, PA, USA.
- Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA, USA.
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7
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Cruz-Garcia Y, Barkovits K, Kohlhaas M, Pickel S, Gulentz M, Heindl C, Pfeiffer K, Eder-Negrin P, Maack C, Marcus K, Kuhn M, Miranda-Laferte E. Nanoenviroments of the β-Subunit of L-Type Voltage-Gated Calcium Channels in Adult Cardiomyocytes. Front Cell Dev Biol 2022; 9:724778. [PMID: 35047492 PMCID: PMC8762238 DOI: 10.3389/fcell.2021.724778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Accepted: 12/06/2021] [Indexed: 11/23/2022] Open
Abstract
In cardiomyocytes, Ca2+ influx through L-type voltage-gated calcium channels (LTCCs) following membrane depolarization regulates crucial Ca2+-dependent processes including duration and amplitude of the action potentials and excitation-contraction coupling. LTCCs are heteromultimeric proteins composed of the Cavα1, Cavβ, Cavα2δ and Cavγ subunits. Here, using ascorbate peroxidase (APEX2)-mediated proximity labeling and quantitative proteomics, we identified 61 proteins in the nanoenvironments of Cavβ2 in cardiomyocytes. These proteins are involved in diverse cellular functions such as cellular trafficking, cardiac contraction, sarcomere organization and excitation-contraction coupling. Moreover, pull-down assays and co-immunoprecipitation analyses revealed that Cavβ2 interacts with the ryanodine receptor 2 (RyR2) in adult cardiomyocytes, probably coupling LTCCs and the RyR2 into a supramolecular complex at the dyads. This interaction is mediated by the Src-homology 3 domain of Cavβ2 and is necessary for an effective pacing frequency-dependent increase of the Ca2+-induced Ca2+ release mechanism in cardiomyocytes.
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Affiliation(s)
| | - Katalin Barkovits
- Medizinisches Proteom-Center, Medical Faculty, Ruhr-University Bochum, Bochum, Germany.,Medical Proteome Analysis, Center for Proteindiagnostics (PRODI), Ruhr-University Bochum, Bochum, Germany
| | - Michael Kohlhaas
- Comprehensive Heart Failure Center, University Hospital Würzburg, Würzburg, Germany
| | - Simone Pickel
- Institute of Physiology, University of Würzburg, Würzburg, Germany
| | - Michelle Gulentz
- Comprehensive Heart Failure Center, University Hospital Würzburg, Würzburg, Germany
| | - Cornelia Heindl
- Institute of Physiology, University of Würzburg, Würzburg, Germany
| | - Kathy Pfeiffer
- Medizinisches Proteom-Center, Medical Faculty, Ruhr-University Bochum, Bochum, Germany.,Medical Proteome Analysis, Center for Proteindiagnostics (PRODI), Ruhr-University Bochum, Bochum, Germany
| | - Petra Eder-Negrin
- Comprehensive Heart Failure Center, University Hospital Würzburg, Würzburg, Germany
| | - Christoph Maack
- Comprehensive Heart Failure Center, University Hospital Würzburg, Würzburg, Germany
| | - Katrin Marcus
- Medizinisches Proteom-Center, Medical Faculty, Ruhr-University Bochum, Bochum, Germany.,Medical Proteome Analysis, Center for Proteindiagnostics (PRODI), Ruhr-University Bochum, Bochum, Germany
| | - Michaela Kuhn
- Institute of Physiology, University of Würzburg, Würzburg, Germany.,Comprehensive Heart Failure Center, University Hospital Würzburg, Würzburg, Germany
| | - Erick Miranda-Laferte
- Institute of Physiology, University of Würzburg, Würzburg, Germany.,Institut für Biologische Informationsprozesse, Molekular- und Zellphysiologie (IBI-1), Forschungszentrum Jülich, Jülich, Germany
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8
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Becker A, Wardas B, Salah H, Amini M, Fecher-Trost C, Sen Q, Martus D, Beck A, Philipp SE, Flockerzi V, Belkacemi A. Cavβ3 Regulates Ca 2+ Signaling and Insulin Expression in Pancreatic β-Cells in a Cell-Autonomous Manner. Diabetes 2021; 70:2532-2544. [PMID: 34426509 PMCID: PMC8564405 DOI: 10.2337/db21-0078] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Accepted: 08/12/2021] [Indexed: 11/13/2022]
Abstract
Voltage-gated Ca2+ (Cav) channels consist of a pore-forming Cavα1 subunit and auxiliary Cavα2-δ and Cavβ subunits. In fibroblasts, Cavβ3, independent of its role as a Cav subunit, reduces the sensitivity to low concentrations of inositol-1,4,5-trisphosphate (IP3). Similarly, Cavβ3 could affect cytosolic calcium concentration ([Ca2 +]) in pancreatic β-cells. In this study, we deleted the Cavβ3-encoding gene Cacnb3 in insulin-secreting rat β-(Ins-1) cells using CRISPR/Cas9. These cells were used as controls to investigate the role of Cavβ3 on Ca2+ signaling, glucose-induced insulin secretion (GIIS), Cav channel activity, and gene expression in wild-type cells in which Cavβ3 and the IP3 receptor were coimmunoprecipitated. Transcript and protein profiling revealed significantly increased levels of insulin transcription factor Mafa, CaMKIV, proprotein convertase subtilisin/kexin type-1, and nitric oxide synthase-1 in Cavβ3-knockout cells. In the absence of Cavβ3, Cav currents were not altered. In contrast, CREB activity, the amount of MAFA protein and GIIS, the extent of IP3-dependent Ca2+ release and the frequency of Ca2+ oscillations were increased. These processes were decreased by the Cavβ3 protein in a concentration-dependent manner. Our study shows that Cavβ3 interacts with the IP3 receptor in isolated β-cells, controls IP3-dependent Ca2+-signaling independently of Cav channel functions, and thereby regulates insulin expression and its glucose-dependent release in a cell-autonomous manner.
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Affiliation(s)
- Alexander Becker
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Barbara Wardas
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Houssein Salah
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Maryam Amini
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Claudia Fecher-Trost
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Qiao Sen
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Damian Martus
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Andreas Beck
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Stephan E Philipp
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Veit Flockerzi
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
| | - Anouar Belkacemi
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Präklinisches Zentrum für Molekulare Signalverarbeitung der Universität des Saarlandes, Homburg, Germany
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9
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Tuluc P, Theiner T, Jacobo-Piqueras N, Geisler SM. Role of High Voltage-Gated Ca 2+ Channel Subunits in Pancreatic β-Cell Insulin Release. From Structure to Function. Cells 2021; 10:2004. [PMID: 34440773 PMCID: PMC8393260 DOI: 10.3390/cells10082004] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 07/27/2021] [Accepted: 08/03/2021] [Indexed: 02/07/2023] Open
Abstract
The pancreatic islets of Langerhans secrete several hormones critical for glucose homeostasis. The β-cells, the major cellular component of the pancreatic islets, secrete insulin, the only hormone capable of lowering the plasma glucose concentration. The counter-regulatory hormone glucagon is secreted by the α-cells while δ-cells secrete somatostatin that via paracrine mechanisms regulates the α- and β-cell activity. These three peptide hormones are packed into secretory granules that are released through exocytosis following a local increase in intracellular Ca2+ concentration. The high voltage-gated Ca2+ channels (HVCCs) occupy a central role in pancreatic hormone release both as a source of Ca2+ required for excitation-secretion coupling as well as a scaffold for the release machinery. HVCCs are multi-protein complexes composed of the main pore-forming transmembrane α1 and the auxiliary intracellular β, extracellular α2δ, and transmembrane γ subunits. Here, we review the current understanding regarding the role of all HVCC subunits expressed in pancreatic β-cell on electrical activity, excitation-secretion coupling, and β-cell mass. The evidence we review was obtained from many seminal studies employing pharmacological approaches as well as genetically modified mouse models. The significance for diabetes in humans is discussed in the context of genetic variations in the genes encoding for the HVCC subunits.
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Affiliation(s)
- Petronel Tuluc
- Centre for Molecular Biosciences, Department of Pharmacology and Toxicology, University of Innsbruck, Innrain 80/82, 6020 Innsbruck, Austria; (T.T.); (N.J.-P.); (S.M.G.)
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10
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Wang H, Bu S, Tang J, Li Y, Liu C, Dong J. PTPN5 promotes follicle-stimulating hormone secretion through regulating intracellular calcium homeostasis. FASEB J 2021; 35:e21756. [PMID: 34270805 DOI: 10.1096/fj.202002752rr] [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: 12/20/2020] [Revised: 05/16/2021] [Accepted: 06/10/2021] [Indexed: 11/11/2022]
Abstract
Protein tyrosine phosphatase non-receptor type 5 (PTPN5), also called striatal-enriched protein tyrosine phosphatase (STEP), is highly expressed in neurons of the basal ganglia, hippocampus, cortex, and related structures, also in the pituitary. Gonadotropins are the key regulator of the reproduction in mammals. In this study, PTPN5 is detected to express in murine pituitary in a developmental manner. Moreover, the expression of PTPN5 in the pituitary is heavily reduced after ovary removal. Follicle-stimulating hormone (FSH) secretion in gonadotropes is regulated by PTPN5 via binding GnRH to GnRH-R. Two parallel signaling pathways, Gs-protein kinase A (PKA)-PTPN5 and Gq-phospholipases C (PLC)-p38 MAPK-PTPN5, cooperatively regulate GnRH-induced FSH secretion. We also show that influx of Ca2+ activates the Ca2+ -dependent phosphatase calcineurin, leading to the phosphorylation and activation of PTPN5. The intracellular release of Ca2+ is reduced via TC2153. In conclusion, blocking or knocking out of PTPN5 reduces the release of FSH in whole pituitary. Mechanically, PTPN5 regulates gonadotropes' function through regulating intracellular calcium homeostasis.
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Affiliation(s)
- Hongmei Wang
- Department of Pharmacology, School of Medicine, Southeast University, Nanjing, China
| | - Siyuan Bu
- Department of Pharmacology, School of Medicine, Southeast University, Nanjing, China
| | - Jiajian Tang
- Department of Pharmacology, School of Medicine, Southeast University, Nanjing, China
| | - Yi Li
- Department of Joint Surgery, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
| | - Chunhua Liu
- Department of Physiology, Shandong First Medical University, Taian, China
| | - Junhong Dong
- Department of Biochemistry, School of Basic Medicine, Weifang Medical University, Weifang, China
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11
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Abu-Halima M, Belkacemi A, Ayesh BM, Simone Becker L, Sindiani AM, Fischer U, Hammadeh M, Keller A, Meese E. MicroRNA-targeting in spermatogenesis: Over-expressions of microRNA-23a/b-3p and its affected targeting of the genes ODF2 and UBQLN3 in spermatozoa of patients with oligoasthenozoospermia. Andrology 2021; 9:1137-1144. [PMID: 33784796 DOI: 10.1111/andr.13004] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 03/02/2021] [Accepted: 03/16/2021] [Indexed: 12/12/2022]
Abstract
BACKGROUND Male infertility is a multifactorial syndrome with diverse phenotypic representations. MicroRNAs (miRNAs) are small, non-coding RNAs that are involved in the post-transcriptional regulation of gene expression. Altered abundance levels of ODF2 and UBQLN3 have been reported in patients with different spermatogenic impairments. However, the transcriptional regulation of these two genes by miR-23a/b-3p is still unclear. OBJECTIVES To investigate experimentally whether miR-23a/b-3p targets the genes ODF2 and UBQLN3 and whether this targeting impacts abundance levels of ODF2 and UBQLN3 in patients with oligoasthenozoospermia. MATERIALS AND METHODS A total of 92 men attending a fertility clinic were included in the study, including 46 oligoasthenozoospermic men and 46 age-matched normozoospermic volunteers who served as controls. Reverse transcription-quantitative PCR (RT-qPCR), Western blot, and dual-luciferase (Firefly-Renilla) assays were used to validate the miRNAs and their target genes. RESULTS RT-qPCR revealed that miR-23a/b-3p was more abundant and ODF2 and UBQLN3 targets were less abundant in men with impaired spermatogenesis. Besides, Western blot shows that ODF2 and UBQLN3 protein levels were reduced in men with impaired spermatogenesis. In silico prediction and dual-luciferase assays revealed that potential links exist between the higher abundance level of miR-23a/b-3p and the lower abundance level of ODF2 and UBQLN3 targets. Mutations in the miR-23a/b-3p-binding site within the 3'UTRs (3'untranslated regions) of ODF2 and UBQLN3 genes resulted in abrogated responsiveness to miR-23a/b-3p. Correlation analysis showed that sperm count, motility, and morphology were negatively correlated with miR-23a/b-3p and positively correlated with the lower abundance level of UBQLN3, while ODF lower abundance level was positively correlated with sperm motility. CONCLUSION Findings indicate that the higher abundance level of miR-23a/b-3p and the lower abundance level of ODF2 and UBQLN3 targets are associated with oligoasthenozoospermia and male subfertility.
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Affiliation(s)
| | - Anouar Belkacemi
- Institute of Experimental and Clinical Pharmacology and Toxicology, Saarland University, Center for Molecular Signaling (PZMS), Homburg, Germany
| | - Basim M Ayesh
- Department of Laboratory Medical Sciences, Alaqsa University, Gaza, Palestine
| | | | - Amer M Sindiani
- Department of Obstetrics and Gynecology and IVF, Jordan University of Science and Technology, Irbid, Jordan
| | - Ulrike Fischer
- Institute of Human Genetics, Saarland University, Homburg, Germany
| | - Mohamad Hammadeh
- Department of Obstetrics and Gynecology and IVF, Saarland University, Homburg, Germany
| | - Andreas Keller
- Chair for Clinical Bioinformatics, Saarland University, Saarbrücken, Germany
| | - Eckart Meese
- Institute of Human Genetics, Saarland University, Homburg, Germany
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12
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Solomon E, Davis-Anderson K, Hovde B, Micheva-Viteva S, Harris JF, Twary S, Iyer R. Global transcriptome profile of the developmental principles of in vitro iPSC-to-motor neuron differentiation. BMC Mol Cell Biol 2021; 22:13. [PMID: 33602141 PMCID: PMC7893891 DOI: 10.1186/s12860-021-00343-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 01/11/2021] [Indexed: 12/30/2022] Open
Abstract
Background Human induced pluripotent stem cells (iPSC) have opened new avenues for regenerative medicine. Consequently, iPSC-derived motor neurons have emerged as potentially viable therapies for spinal cord injuries and neurodegenerative disorders including Amyotrophic Lateral Sclerosis. However, direct clinical application of iPSC bears in itself the risk of tumorigenesis and other unforeseeable genetic or epigenetic abnormalities. Results Employing RNA-seq technology, we identified and characterized gene regulatory networks triggered by in vitro chemical reprogramming of iPSC into cells with the molecular features of motor neurons (MNs) whose function in vivo is to innervate effector organs. We present meta-transcriptome signatures of 5 cell types: iPSCs, neural stem cells, motor neuron progenitors, early motor neurons, and mature motor neurons. In strict response to the chemical stimuli, along the MN differentiation axis we observed temporal downregulation of tumor growth factor-β signaling pathway and consistent activation of sonic hedgehog, Wnt/β-catenin, and Notch signaling. Together with gene networks defining neuronal differentiation (neurogenin 2, microtubule-associated protein 2, Pax6, and neuropilin-1), we observed steady accumulation of motor neuron-specific regulatory genes, including Islet-1 and homeobox protein HB9. Interestingly, transcriptome profiling of the differentiation process showed that Ca2+ signaling through cAMP and LPC was downregulated during the conversion of the iPSC to neural stem cells and key regulatory gene activity of the pathway remained inhibited until later stages of motor neuron formation. Pathways shaping the neuronal development and function were well-represented in the early motor neuron cells including, neuroactive ligand-receptor interactions, axon guidance, and the cholinergic synapse formation. A notable hallmark of our in vitro motor neuron maturation in monoculture was the activation of genes encoding G-coupled muscarinic acetylcholine receptors and downregulation of the ionotropic nicotinic acetylcholine receptors expression. We observed the formation of functional neuronal networks as spontaneous oscillations in the extracellular action potentials recorded on multi-electrode array chip after 20 days of differentiation. Conclusions Detailed transcriptome profile of each developmental step from iPSC to motor neuron driven by chemical induction provides the guidelines to novel therapeutic approaches in the re-construction efforts of muscle innervation. Supplementary Information The online version contains supplementary material available at 10.1186/s12860-021-00343-z.
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Affiliation(s)
- Emilia Solomon
- Los Alamos National Laboratory, Bioscience Division, Los Alamos, NM, USA
| | | | - Blake Hovde
- Los Alamos National Laboratory, Bioscience Division, Los Alamos, NM, USA
| | | | | | - Scott Twary
- Los Alamos National Laboratory, Bioscience Division, Los Alamos, NM, USA
| | - Rashi Iyer
- Los Alamos National Laboratory, Analytics, Intelligence, and Technology Division, Los Alamos, NM, USA.
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13
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Mukherjee A, Katiyar R, Dembla E, Dembla M, Kumar P, Belkacemi A, Jung M, Beck A, Flockerzi V, Schwarz K, Schmitz F. Disturbed Presynaptic Ca 2+ Signaling in Photoreceptors in the EAE Mouse Model of Multiple Sclerosis. iScience 2020; 23:101830. [PMID: 33305185 PMCID: PMC7711289 DOI: 10.1016/j.isci.2020.101830] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 10/10/2020] [Accepted: 11/16/2020] [Indexed: 02/06/2023] Open
Abstract
Multiple sclerosis (MS) is a demyelinating disease caused by an auto-reactive immune system. Recent studies also demonstrated synapse dysfunctions in MS patients and MS mouse models. We previously observed decreased synaptic vesicle exocytosis in photoreceptor synapses in the EAE mouse model of MS at an early, preclinical stage. In the present study, we analyzed whether synaptic defects are associated with altered presynaptic Ca2+ signaling. Using high-resolution immunolabeling, we found a reduced signal intensity of Cav-channels and RIM2 at active zones in early, preclinical EAE. In line with these morphological alterations, depolarization-evoked increases of presynaptic Ca2+ were significantly smaller. In contrast, basal presynaptic Ca2+ was elevated. We observed a decreased expression of Na+/K+-ATPase and plasma membrane Ca2+ ATPase 2 (PMCA2), but not PMCA1, in photoreceptor terminals of EAE mice that could contribute to elevated basal Ca2+. Thus, complex Ca2+ signaling alterations contribute to synaptic dysfunctions in photoreceptors in early EAE. Less Cav-channels and RIM2 at the active zones of EAE photoreceptor synapses Decreased depolarization-evoked Ca2+-responses in EAE photoreceptor synapses Elevated basal, resting Ca2+ levels in preclinical EAE photoreceptor terminals Decreased expression of PMCA2 and Na+/K+-ATPase in EAE photoreceptor synapses
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Affiliation(s)
- Amrita Mukherjee
- Institute of Anatomy and Cell Biology, Department of Neuroanatomy, Saarland University, Medical School, 66421 Homburg, Germany
| | - Rashmi Katiyar
- Institute of Anatomy and Cell Biology, Department of Neuroanatomy, Saarland University, Medical School, 66421 Homburg, Germany
| | - Ekta Dembla
- Institute of Anatomy and Cell Biology, Department of Neuroanatomy, Saarland University, Medical School, 66421 Homburg, Germany
| | - Mayur Dembla
- Institute of Anatomy and Cell Biology, Department of Neuroanatomy, Saarland University, Medical School, 66421 Homburg, Germany
| | - Praveen Kumar
- Institute of Anatomy and Cell Biology, Department of Neuroanatomy, Saarland University, Medical School, 66421 Homburg, Germany
| | - Anouar Belkacemi
- Institute of Experimental and Clinical Pharmacology and Toxicology, Saarland University, Medical School, 66421 Homburg, Germany
| | - Martin Jung
- Institute of Medical Biochemistry and Molecular Biology, Saarland University, Medical School, 66421 Homburg, Germany
| | - Andreas Beck
- Institute of Experimental and Clinical Pharmacology and Toxicology, Saarland University, Medical School, 66421 Homburg, Germany
| | - Veit Flockerzi
- Institute of Experimental and Clinical Pharmacology and Toxicology, Saarland University, Medical School, 66421 Homburg, Germany
| | - Karin Schwarz
- Institute of Anatomy and Cell Biology, Department of Neuroanatomy, Saarland University, Medical School, 66421 Homburg, Germany
| | - Frank Schmitz
- Institute of Anatomy and Cell Biology, Department of Neuroanatomy, Saarland University, Medical School, 66421 Homburg, Germany
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Trop2 inhibition of P16 expression and the cell cycle promotes intracellular calcium release in OSCC. Int J Biol Macromol 2020; 164:2409-2417. [PMID: 32768481 DOI: 10.1016/j.ijbiomac.2020.07.234] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 07/22/2020] [Accepted: 07/22/2020] [Indexed: 12/13/2022]
Abstract
Trop2 is an intracellular calcium signal transducer and a prognostic biomarker in many cancers. P16 is a cell cycle gene that negatively regulates cell proliferation and division in most human cancers. Oral squamous cell carcinoma (OSCC) is a common malignant tumor subgroup of head and neck squamous cell carcinoma worldwide. Both Ca2+-dependent and cell cycle signaling pathways play vital roles in OSCC, although the molecular mechanisms remain to be elucidated. We aimed to examine the function of Trop2 and P16 in regulating intracellular calcium ions and the cell cycle in OSCC cell lines. Furtherly, the mRNA and protein expression levels of Trop2 and P16 in OSCC tissue samples were assessed, and their function was evaluated as potential clinical prognostic biomarkers. Trop2 promoted intracellular calcium ion release in OSCC and induced S phase of the cell cycle. Moreover, Trop2-mediated Ca2+ inhibited P16 expression through the AMP-activated protein kinase pathway in OSCC. Interestingly, P16 overexpression could not reverse these phenomena in vitro. We also demonstrated that human OSCC tissues showed high Trop2 mRNA and protein expression, and Trop2+/P16- expression is an independent prognostic marker for OSCC patients. Our data suggest that Trop2+/P16- may be a valuable prognostic marker for OSCC and that Trop2 inhibits P16 expression and induces S phase by promoting intracellular calcium release in OSCC.
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15
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Inositol 1,4,5-Trisphosphate Receptors in Human Disease: A Comprehensive Update. J Clin Med 2020; 9:jcm9041096. [PMID: 32290556 PMCID: PMC7231134 DOI: 10.3390/jcm9041096] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 03/30/2020] [Accepted: 04/10/2020] [Indexed: 12/22/2022] Open
Abstract
Inositol 1,4,5-trisphosphate receptors (ITPRs) are intracellular calcium release channels located on the endoplasmic reticulum of virtually every cell. Herein, we are reporting an updated systematic summary of the current knowledge on the functional role of ITPRs in human disorders. Specifically, we are describing the involvement of its loss-of-function and gain-of-function mutations in the pathogenesis of neurological, immunological, cardiovascular, and neoplastic human disease. Recent results from genome-wide association studies are also discussed.
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16
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Cataloguing and Selection of mRNAs Localized to Dendrites in Neurons and Regulated by RNA-Binding Proteins in RNA Granules. Biomolecules 2020; 10:biom10020167. [PMID: 31978946 PMCID: PMC7072219 DOI: 10.3390/biom10020167] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 01/18/2020] [Accepted: 01/20/2020] [Indexed: 12/15/2022] Open
Abstract
Spatiotemporal translational regulation plays a key role in determining cell fate and function. Specifically, in neurons, local translation in dendrites is essential for synaptic plasticity and long-term memory formation. To achieve local translation, RNA-binding proteins in RNA granules regulate target mRNA stability, localization, and translation. To date, mRNAs localized to dendrites have been identified by comprehensive analyses. In addition, mRNAs associated with and regulated by RNA-binding proteins have been identified using various methods in many studies. However, the results obtained from these numerous studies have not been compiled together. In this review, we have catalogued mRNAs that are localized to dendrites and are associated with and regulated by the RNA-binding proteins fragile X mental retardation protein (FMRP), RNA granule protein 105 (RNG105, also known as Caprin1), Ras-GAP SH3 domain binding protein (G3BP), cytoplasmic polyadenylation element binding protein 1 (CPEB1), and staufen double-stranded RNA binding proteins 1 and 2 (Stau1 and Stau2) in RNA granules. This review provides comprehensive information on dendritic mRNAs, the neuronal functions of mRNA-encoded proteins, the association of dendritic mRNAs with RNA-binding proteins in RNA granules, and the effects of RNA-binding proteins on mRNA regulation. These findings provide insights into the mechanistic basis of protein-synthesis-dependent synaptic plasticity and memory formation and contribute to future efforts to understand the physiological implications of local regulation of dendritic mRNAs in neurons.
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17
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Investigating the InsP 3 Receptor in Living Cells by Caged InsP 3. Methods Mol Biol 2019. [PMID: 31773575 DOI: 10.1007/978-1-0716-0167-9_10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
The inositol 1,4,5-trisphosphate receptor (InsP3R) operates as an intracellular ligand-gated Ca2+ channel and plays a pivotal role in cellular Ca2+ homeostasis across all living cells. It is activated following membrane receptor-ligand interactions and stimulation of subsequent signaling cascades involving the enzymatic breakdown of the membrane lipid phosphatidyl-4,5-bisphosphate (PIP2) into the membrane-delimited second messenger diacylglycerol (DAG) and the diffusible second messenger inositol-1,4,5-trisphophate (InsP3). Modulation of InsP3R's activity is thus involved in a plethora of physiological and pathological processes. Here we combine membrane permeable photoactive caged-InsP3 with Ca2+ imaging techniques in living cells to study the channel's in vivo properties. Using UV-flashes of variable energy, the activity properties of InsP3R can be investigated in great detail in its native environment.
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Guerra MJ, González‐Jamett AM, Báez‐Matus X, Navarro‐Quezada N, Martínez AD, Neely A, Cárdenas AM. The Ca2+channel subunit CaVβ2a‐subunit down‐regulates voltage‐activated ion current densities by disrupting actin‐dependent traffic in chromaffin cells. J Neurochem 2019; 151:703-715. [DOI: 10.1111/jnc.14851] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 05/01/2019] [Accepted: 08/05/2019] [Indexed: 12/11/2022]
Affiliation(s)
- María J. Guerra
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia Universidad de Valparaíso Valparaíso Chile
| | - Arlek M. González‐Jamett
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia Universidad de Valparaíso Valparaíso Chile
| | - Ximena Báez‐Matus
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia Universidad de Valparaíso Valparaíso Chile
| | - Nieves Navarro‐Quezada
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia Universidad de Valparaíso Valparaíso Chile
| | - Agustín D. Martínez
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia Universidad de Valparaíso Valparaíso Chile
| | - Alan Neely
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia Universidad de Valparaíso Valparaíso Chile
| | - Ana M. Cárdenas
- Facultad de Ciencias, Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia Universidad de Valparaíso Valparaíso Chile
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Translocatable voltage-gated Ca 2+ channel β subunits in α1-β complexes reveal competitive replacement yet no spontaneous dissociation. Proc Natl Acad Sci U S A 2018; 115:E9934-E9943. [PMID: 30257950 DOI: 10.1073/pnas.1809762115] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
β subunits of high voltage-gated Ca2+ (CaV) channels promote cell-surface expression of pore-forming α1 subunits and regulate channel gating through binding to the α-interaction domain (AID) in the first intracellular loop. We addressed the stability of CaV α1B-β interactions by rapamycin-translocatable CaV β subunits that allow drug-induced sequestration and uncoupling of the β subunit from CaV2.2 channel complexes in intact cells. Without CaV α1B/α2δ1, all modified β subunits, except membrane-tethered β2a and β2e, are in the cytosol and rapidly translocate upon rapamycin addition to anchors on target organelles: plasma membrane, mitochondria, or endoplasmic reticulum. In cells coexpressing CaV α1B/α2δ1 subunits, the translocatable β subunits colocalize at the plasma membrane with α1B and stay there after rapamycin application, indicating that interactions between α1B and bound β subunits are very stable. However, the interaction becomes dynamic when other competing β isoforms are coexpressed. Addition of rapamycin, then, switches channel gating and regulation by phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] lipid. Thus, expression of free β isoforms around the channel reveals a dynamic aspect to the α1B-β interaction. On the other hand, translocatable β subunits with AID-binding site mutations are easily dissociated from CaV α1B on the addition of rapamycin, decreasing current amplitude and PI(4,5)P2 sensitivity. Furthermore, the mutations slow CaV2.2 current inactivation and shift the voltage dependence of activation to more positive potentials. Mutated translocatable β subunits work similarly in CaV2.3 channels. In sum, the strong interaction of CaV α1B-β subunits can be overcome by other free β isoforms, permitting dynamic changes in channel properties in intact cells.
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