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Wawrzkiewicz-Jałowiecka A, Lalik A, Lukasiak A, Richter-Laskowska M, Trybek P, Ejfler M, Opałka M, Wardejn S, Delfino DV. Potassium Channels, Glucose Metabolism and Glycosylation in Cancer Cells. Int J Mol Sci 2023; 24:ijms24097942. [PMID: 37175655 PMCID: PMC10178682 DOI: 10.3390/ijms24097942] [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: 03/29/2023] [Revised: 04/24/2023] [Accepted: 04/25/2023] [Indexed: 05/15/2023] Open
Abstract
Potassium channels emerge as one of the crucial groups of proteins that shape the biology of cancer cells. Their involvement in processes like cell growth, migration, or electric signaling, seems obvious. However, the relationship between the function of K+ channels, glucose metabolism, and cancer glycome appears much more intriguing. Among the typical hallmarks of cancer, one can mention the switch to aerobic glycolysis as the most favorable mechanism for glucose metabolism and glycome alterations. This review outlines the interconnections between the expression and activity of potassium channels, carbohydrate metabolism, and altered glycosylation in cancer cells, which have not been broadly discussed in the literature hitherto. Moreover, we propose the potential mediators for the described relations (e.g., enzymes, microRNAs) and the novel promising directions (e.g., glycans-orinented drugs) for further research.
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Affiliation(s)
- Agata Wawrzkiewicz-Jałowiecka
- Department of Physical Chemistry and Technology of Polymers, Silesian University of Technology, 44-100 Gliwice, Poland
| | - Anna Lalik
- Department of Systems Biology and Engineering, Silesian University of Technology, 44-100 Gliwice, Poland
- Biotechnology Center, Silesian University of Technology, 44-100 Gliwice, Poland
| | - Agnieszka Lukasiak
- Department of Physics and Biophysics, Institute of Biology, Warsaw University of Life Sciences, 02-776 Warsaw, Poland
| | - Monika Richter-Laskowska
- The Centre for Biomedical Engineering, Łukasiewicz Research Network-Krakow Institute of Technology, 30-418 Krakow, Poland
| | - Paulina Trybek
- Institute of Physics, University of Silesia in Katowice, 41-500 Chorzów, Poland
| | - Maciej Ejfler
- Faculty of Automatic Control, Electronics and Computer Science, Silesian University of Technology, 44-100 Gliwice, Poland
| | - Maciej Opałka
- Faculty of Automatic Control, Electronics and Computer Science, Silesian University of Technology, 44-100 Gliwice, Poland
| | - Sonia Wardejn
- Faculty of Automatic Control, Electronics and Computer Science, Silesian University of Technology, 44-100 Gliwice, Poland
| | - Domenico V Delfino
- Section of Pharmacology, Department of Medicine and Surgery, University of Perugia, 06129 Perugia, Italy
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2
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Ullrich J, Ohlhoff C, Dondapati SK, Zemella A, Kubick S. Evaluation of the Ion Channel Assembly in a Eukaryotic Cell-Free System Focusing on Two-Pore Domain Potassium Channels K2P. Int J Mol Sci 2023; 24:ijms24076299. [PMID: 37047271 PMCID: PMC10094441 DOI: 10.3390/ijms24076299] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 03/20/2023] [Accepted: 03/24/2023] [Indexed: 03/30/2023] Open
Abstract
Oligomeric ion channels are abundant in nature. However, the recombinant expression in cell culture-based systems remains tedious and challenging due to negative side effects, limiting the understanding of their role in health and disease. Accordingly, in this work, we demonstrate the cell-free synthesis (CFS) as an alternative platform to study the assembly of two-pore domain potassium channels (K2P) within endogenous endoplasmic reticulum-derived microsomes. Exploiting the open nature of CFS, we investigate the cotranslational translocation of TREK-2 into the microsomes and suggest a cotranslational assembly with typical single-channel behavior in planar lipid-bilayer electrophysiology. The heteromeric assembly of K2P channels is a contentious matter, accordingly we prove the successful assembly of TREK-2 with TWIK-1 using a biomolecular fluorescence complementation assay, Western blot analysis and autoradiography. The results demonstrate that TREK-2 homodimer assembly is the initial step, followed by heterodimer formation with the nascent TWIK-1, providing evidence of the intergroup heterodimerization of TREK-2 and TWIK-1 in eukaryotic CFS. Since K2P channels are involved in various pathophysiological conditions, including pain and nociception, CFS paves the way for in-depth functional studies and related pharmacological interventions. This study highlights the versatility of the eukaryotic CFS platform for investigating ion channel assembly in a native-like environment.
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Affiliation(s)
- Jessica Ullrich
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg 13, 14476 Potsdam, Germany
- Institute of Biotechnology, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany
| | - Carsten Ohlhoff
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg 13, 14476 Potsdam, Germany
- Institute of Biotechnology, Technische Universität Berlin, Straße des 17. Juni 135, 10623 Berlin, Germany
| | - Srujan Kumar Dondapati
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg 13, 14476 Potsdam, Germany
- Correspondence:
| | - Anne Zemella
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg 13, 14476 Potsdam, Germany
| | - Stefan Kubick
- Fraunhofer Institute for Cell Therapy and Immunology (IZI), Branch Bioanalytics and Bioprocesses (IZI-BB), Am Mühlenberg 13, 14476 Potsdam, Germany
- Institute of Chemistry and Biochemistry, Freie Universität Berlin, Thielallee 63, 14195 Berlin, Germany
- Faculty of Health Sciences, Joint Faculty of the Brandenburg University of Technology Cottbus-Senftenberg, the Brandenburg Medical School Theodor Fontane and the University of Potsdam, 14476 Potsdam, Germany
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3
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Jin Y, Mao Y, Chen D, Tai Y, Hu R, Yang CL, Zhou J, Chen L, Liu X, Gu E, Jia C, Zhang Z, Tao W. Thalamocortical circuits drive remifentanil-induced postoperative hyperalgesia. J Clin Invest 2022; 132:158742. [PMID: 36519547 PMCID: PMC9754001 DOI: 10.1172/jci158742] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 10/18/2022] [Indexed: 12/15/2022] Open
Abstract
Remifentanil-induced hyperalgesia (RIH) is a severe but common postoperative clinical problem with elusive underlying neural mechanisms. Here, we discovered that glutamatergic neurons in the thalamic ventral posterolateral nucleus (VPLGlu) exhibited significantly elevated burst firing accompanied by upregulation of Cav3.1 T-type calcium channel expression and function in RIH model mice. In addition, we identified a glutamatergic neuronal thalamocortical circuit in the VPL projecting to hindlimb primary somatosensory cortex glutamatergic neurons (S1HLGlu) that mediated RIH. In vivo calcium imaging and multi-tetrode recordings revealed heightened S1HLGlu neuronal activity during RIH. Moreover, preoperative suppression of Cav3.1-dependent burst firing in VPLGlu neurons or chemogenetic inhibition of VPLGlu neuronal terminals in the S1HL abolished the increased S1HLGlu neuronal excitability while alleviating RIH. Our findings suggest that remifentanil induces postoperative hyperalgesia by upregulating T-type calcium channel-dependent burst firing in VPLGlu neurons to activate S1HLGlu neurons, thus revealing an ion channel-mediated neural circuit basis for RIH that can guide analgesic development.
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Affiliation(s)
- Yan Jin
- Stroke Center and Department of Neurology and,Department of Anesthesiology and Pain Medicine, The First Affiliated Hospital of University of Science and Technology of China (USTC), Division of Life Sciences and Medicine, USTC, Hefei, China
| | - Yu Mao
- Stroke Center and Department of Neurology and,Department of Anesthesiology, The First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Danyang Chen
- Department of Anesthesiology and Pain Medicine, The First Affiliated Hospital of University of Science and Technology of China (USTC), Division of Life Sciences and Medicine, USTC, Hefei, China
| | - Yingju Tai
- Department of Anesthesiology and Pain Medicine, The First Affiliated Hospital of University of Science and Technology of China (USTC), Division of Life Sciences and Medicine, USTC, Hefei, China
| | - Rui Hu
- Department of Anesthesiology, The Third Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Chen-Ling Yang
- Department of Physiology, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
| | - Jing Zhou
- Department of head, neck, and breast Surgery, Western district of the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, USTC, Hefei, China
| | - Lijian Chen
- Department of Anesthesiology, The First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Xuesheng Liu
- Department of Anesthesiology, The First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Erwei Gu
- Department of Anesthesiology, The First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Chunhui Jia
- Department of Anesthesiology and Pain Medicine, The First Affiliated Hospital of University of Science and Technology of China (USTC), Division of Life Sciences and Medicine, USTC, Hefei, China
| | - Zhi Zhang
- Department of Anesthesiology and Pain Medicine, The First Affiliated Hospital of University of Science and Technology of China (USTC), Division of Life Sciences and Medicine, USTC, Hefei, China
| | - Wenjuan Tao
- Stroke Center and Department of Neurology and,Department of Physiology, School of Basic Medical Sciences, Anhui Medical University, Hefei, China
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4
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Swierczynska MM, Betz MJ, Colombi M, Dazert E, Jenö P, Moes S, Pfaff C, Glatz K, Reincke M, Beuschlein F, Donath MY, Hall MN. Proteomic Landscape of Aldosterone-Producing Adenoma. Hypertension 2019; 73:469-480. [PMID: 30580688 DOI: 10.1161/hypertensionaha.118.11733] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Primary aldosteronism is a disease of excessive production of adrenal steroid hormones and the most common cause of endocrine hypertension. Primary aldosteronism results mainly from bilateral adrenal hyperplasia or unilateral aldosterone-producing adenoma (APA). Primary aldosteronism cause at the molecular level is incompletely understood and a targeted treatment preventing excessive adrenal steroid production is not available. Here, we perform deep quantitative proteomic and phosphoproteomic profiling of 6 pairs of APA and adjacent nontumoral adrenal cortex. We show that increased steroidogenesis in APA is accompanied by upregulation of steroidogenic enzymes (HSD3B2, CYP21A2, CYP11B2) and of proteins involved in cholesterol uptake (LSR). We demonstrate that HSD3B2 is phosphorylated at Ser95 or 96 and identify a novel phosphorylation site, Ser489, in CYP21A2, suggesting that steroidogenic enzymes are regulated by phosphorylation. Our analysis also reveals altered ECM (extracellular matrix) composition in APA that affects ECM-cell surface interactions and actin cytoskeleton rearrangements. We show that RHOC, a GTPase controlling actin organization in response to extracellular stimuli, is upregulated in APA and promotes expression of the aldosterone synthase gene CYP11B2. Our data also indicate deregulation of protein N-glycosylation and GABAergic signaling in APAs. Finally, we find that mTORC1 (mammalian target of rapamycin complex 1) signaling is the major pathway deregulated in APA. Our study provides a rich resource for future research on the molecular mechanisms of primary aldosteronism.
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Affiliation(s)
- Marta M Swierczynska
- From the Biozentrum, University of Basel, Switzerland (M.M.S., M.C., E.D., P.J., S.M., C.P., M.N.H.), University Hospital Basel, Switzerland
| | - Matthias J Betz
- Clinic of Endocrinology, Diabetes & Metabolism (M.J.B., M.Y.D.), University Hospital Basel, Switzerland
| | - Marco Colombi
- From the Biozentrum, University of Basel, Switzerland (M.M.S., M.C., E.D., P.J., S.M., C.P., M.N.H.), University Hospital Basel, Switzerland
| | - Eva Dazert
- From the Biozentrum, University of Basel, Switzerland (M.M.S., M.C., E.D., P.J., S.M., C.P., M.N.H.), University Hospital Basel, Switzerland
| | - Paul Jenö
- From the Biozentrum, University of Basel, Switzerland (M.M.S., M.C., E.D., P.J., S.M., C.P., M.N.H.), University Hospital Basel, Switzerland
| | - Suzette Moes
- From the Biozentrum, University of Basel, Switzerland (M.M.S., M.C., E.D., P.J., S.M., C.P., M.N.H.), University Hospital Basel, Switzerland
| | - Cécile Pfaff
- From the Biozentrum, University of Basel, Switzerland (M.M.S., M.C., E.D., P.J., S.M., C.P., M.N.H.), University Hospital Basel, Switzerland
| | - Katharina Glatz
- Institute of Pathology (K.G.), University Hospital Basel, Switzerland
| | - Martin Reincke
- Medizinische Klinik und Poliklinik IV, Klinikum der Universität München, Munich, Germany (M.R., F.B.)
| | - Felix Beuschlein
- Medizinische Klinik und Poliklinik IV, Klinikum der Universität München, Munich, Germany (M.R., F.B.).,Klinik für Endokrinologie, Diabetologie und Klinische Ernährung, UniversitätsSpital Zürich, Switzerland (F.B.)
| | - Marc Y Donath
- Clinic of Endocrinology, Diabetes & Metabolism (M.J.B., M.Y.D.), University Hospital Basel, Switzerland
| | - Michael N Hall
- From the Biozentrum, University of Basel, Switzerland (M.M.S., M.C., E.D., P.J., S.M., C.P., M.N.H.), University Hospital Basel, Switzerland
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5
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N-Glycosylation of TREK-1/hK 2P2.1 Two-Pore-Domain Potassium (K 2P) Channels. Int J Mol Sci 2019; 20:ijms20205193. [PMID: 31635148 PMCID: PMC6829520 DOI: 10.3390/ijms20205193] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2019] [Revised: 10/15/2019] [Accepted: 10/18/2019] [Indexed: 01/11/2023] Open
Abstract
Mechanosensitive hTREK-1 two-pore-domain potassium (hK2P2.1) channels give rise to background currents that control cellular excitability. Recently, TREK-1 currents have been linked to the regulation of cardiac rhythm as well as to hypertrophy and fibrosis. Even though the pharmacological and biophysical characteristics of hTREK-1 channels have been widely studied, relatively little is known about their posttranslational modifications. This study aimed to evaluate whether hTREK-1 channels are N-glycosylated and whether glycosylation may affect channel functionality. Following pharmacological inhibition of N-glycosylation, enzymatic digestion or mutagenesis, immunoblots of Xenopus laevis oocytes and HEK-293T cell lysates were used to assess electrophoretic mobility. Two-electrode voltage clamp measurements were employed to study channel function. TREK-1 channel subunits undergo N-glycosylation at asparagine residues 110 and 134. The presence of sugar moieties at these two sites increases channel function. Detection of glycosylation-deficient mutant channels in surface fractions and recordings of macroscopic potassium currents mediated by these subunits demonstrated that nonglycosylated hTREK-1 channel subunits are able to reach the cell surface in general but with seemingly reduced efficiency compared to glycosylated subunits. These findings extend our understanding of the regulation of hTREK-1 currents by posttranslational modifications and provide novel insights into how altered ion channel glycosylation may promote arrhythmogenesis.
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6
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Incorporation of one N-glycosylation-deficient subunit within a tetramer of HCN2 channel is tolerated. Neuroreport 2019; 30:998-1003. [PMID: 31503201 DOI: 10.1097/wnr.0000000000001310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are glycoproteins N-glycosylated at a specific asparagine residue in the S5-S6 linker region. Previous reports suggested that N-glycosylation-deficient HCN2 N380Q (NQ) channels fail to properly target to the plasma membrane and are unable to form functional ion channels. HCN channels are known to homo- and hetero-oligomerize and it is not known whether HCN2-NQ subunits can oligomerize with wild type (wt) N-glycosylated subunits to form a tetrameric assembly. In the present study, homomeric NQ-mutant resulted in no current, cRNA titration experiments controlling the amount of wt-to-NQ injected into Xenopus oocytes indicated that the observed currents were consistent with a model where presence of a single nonglycosylated subunit in a tetrameric oligomer is tolerated forming functional channels. The activation voltage-dependence described by half-activation voltage and slope factor, and the reversal potential of the wt-NQ oligomeric channels were identical to the wt only tetrameric channels. Further incorporation of the nonglycosylated subunit rendered the channels nonconductive or not incorporated into the plasma membrane.
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7
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Wiedmann F, Schlund D, Voigt N, Ratte A, Kraft M, Katus HA, Schmidt C. N-glycosylation-dependent regulation of hK 2P17.1 currents. Mol Biol Cell 2019; 30:1425-1436. [PMID: 30969900 PMCID: PMC6724686 DOI: 10.1091/mbc.e18-10-0687] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Two pore-domain potassium (K2P) channels mediate potassium background currents that stabilize the resting membrane potential and facilitate action potential repolarization. In the human heart, hK2P17.1 channels are predominantly expressed in the atria and Purkinje cells. Reduced atrial hK2P17.1 protein levels were described in patients with atrial fibrillation or heart failure. Genetic alterations in hK2P17.1 were associated with cardiac conduction disorders. Little is known about posttranslational modifications of hK2P17.1. Here, we characterized glycosylation of hK2P17.1 and investigated how glycosylation alters its surface expression and activity. Wild-type hK2P17.1 channels and channels lacking specific glycosylation sites were expressed in Xenopus laevis oocytes, HEK-293T cells, and HeLa cells. N-glycosylation was disrupted using N-glycosidase F and tunicamycin. hK2P17.1 expression and activity were assessed using immunoblot analysis and a two-electrode voltage clamp technique. Channel subunits of hK2P17.1 harbor two functional N-glycosylation sites at positions N65 and N94. In hemi-glycosylated hK2P17.1 channels, functionality and membrane trafficking remain preserved. Disruption of both N-glycosylation sites results in loss of hK2P17.1 currents, presumably caused by impaired surface expression. This study confirms diglycosylation of hK2P17.1 channel subunits and its pivotal role in cell-surface targeting. Our findings underline the functional relevance of N-glycosylation in biogenesis and membrane trafficking of ion channels.
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Affiliation(s)
- Felix Wiedmann
- Department of Cardiology, University of Heidelberg, 69120 Heidelberg, Germany.,DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg/Mannheim, University of Heidelberg, 69120 Heidelberg, Germany.,HCR, Heidelberg Center for Heart Rhythm Disorders, University of Heidelberg, 69120 Heidelberg, Germany
| | - Daniel Schlund
- Department of Cardiology, University of Heidelberg, 69120 Heidelberg, Germany
| | - Niels Voigt
- Institute of Pharmacology and Toxicology, University Medical Center Göttingen, Georg-August University of Göttingen, 37073 Göttingen, Germany.,DZHK (German Center for Cardiovascular Research), Partner Site Göttingen, University of Göttingen, 37073 Göttingen, Germany
| | - Antonius Ratte
- Department of Cardiology, University of Heidelberg, 69120 Heidelberg, Germany.,DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg/Mannheim, University of Heidelberg, 69120 Heidelberg, Germany.,HCR, Heidelberg Center for Heart Rhythm Disorders, University of Heidelberg, 69120 Heidelberg, Germany
| | - Manuel Kraft
- Department of Cardiology, University of Heidelberg, 69120 Heidelberg, Germany.,DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg/Mannheim, University of Heidelberg, 69120 Heidelberg, Germany.,HCR, Heidelberg Center for Heart Rhythm Disorders, University of Heidelberg, 69120 Heidelberg, Germany
| | - Hugo A Katus
- Department of Cardiology, University of Heidelberg, 69120 Heidelberg, Germany.,DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg/Mannheim, University of Heidelberg, 69120 Heidelberg, Germany.,HCR, Heidelberg Center for Heart Rhythm Disorders, University of Heidelberg, 69120 Heidelberg, Germany
| | - Constanze Schmidt
- Department of Cardiology, University of Heidelberg, 69120 Heidelberg, Germany.,DZHK (German Center for Cardiovascular Research), Partner Site Heidelberg/Mannheim, University of Heidelberg, 69120 Heidelberg, Germany.,HCR, Heidelberg Center for Heart Rhythm Disorders, University of Heidelberg, 69120 Heidelberg, Germany
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Capera J, Serrano-Novillo C, Navarro-Pérez M, Cassinelli S, Felipe A. The Potassium Channel Odyssey: Mechanisms of Traffic and Membrane Arrangement. Int J Mol Sci 2019; 20:ijms20030734. [PMID: 30744118 PMCID: PMC6386995 DOI: 10.3390/ijms20030734] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 02/06/2019] [Accepted: 02/08/2019] [Indexed: 12/29/2022] Open
Abstract
Ion channels are transmembrane proteins that conduct specific ions across biological membranes. Ion channels are present at the onset of many cellular processes, and their malfunction triggers severe pathologies. Potassium channels (KChs) share a highly conserved signature that is necessary to conduct K⁺ through the pore region. To be functional, KChs require an exquisite regulation of their subcellular location and abundance. A wide repertoire of signatures facilitates the proper targeting of the channel, fine-tuning the balance that determines traffic and location. These signature motifs can be part of the secondary or tertiary structure of the protein and are spread throughout the entire sequence. Furthermore, the association of the pore-forming subunits with different ancillary proteins forms functional complexes. These partners can modulate traffic and activity by adding their own signatures as well as by exposing or masking the existing ones. Post-translational modifications (PTMs) add a further dimension to traffic regulation. Therefore, the fate of a KCh is not fully dependent on a gene sequence but on the balance of many other factors regulating traffic. In this review, we assemble recent evidence contributing to our understanding of the spatial expression of KChs in mammalian cells. We compile specific signatures, PTMs, and associations that govern the destination of a functional channel.
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Affiliation(s)
- Jesusa Capera
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain.
| | - Clara Serrano-Novillo
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain.
| | - María Navarro-Pérez
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain.
| | - Silvia Cassinelli
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain.
| | - Antonio Felipe
- Molecular Physiology Laboratory, Departament de Bioquímica i Biomedicina Molecular, Institut de Biomedicina (IBUB), Universitat de Barcelona, Avda. Diagonal 643, 08028 Barcelona, Spain.
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Andreoletti G, Seaby EG, Dewing JM, O'Kelly I, Lachlan K, Gilbert RD, Ennis S. AMMECR1: a single point mutation causes developmental delay, midface hypoplasia and elliptocytosis. J Med Genet 2016; 54:269-277. [PMID: 27811305 PMCID: PMC5502304 DOI: 10.1136/jmedgenet-2016-104100] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 08/03/2016] [Accepted: 09/26/2016] [Indexed: 11/12/2022]
Abstract
Background Deletions in the Xq22.3–Xq23 region, inclusive of COL4A5, have been associated with a contiguous gene deletion syndrome characterised by Alport syndrome with intellectual disability (Mental retardation), Midface hypoplasia and Elliptocytosis (AMME). The extrarenal biological and clinical significance of neighbouring genes to the Alport locus has been largely speculative. We sought to discover a genetic cause for two half-brothers presenting with nephrocalcinosis, early speech and language delay and midface hypoplasia with submucous cleft palate and bifid uvula. Methods Whole exome sequencing was undertaken on maternal half-siblings. In-house genomic analysis included extraction of all shared variants on the X chromosome in keeping with X-linked inheritance. Patient-specific mutants were transfected into three cell lines and microscopically visualised to assess the nuclear expression pattern of the mutant protein. Results In the affected half-brothers, we identified a hemizygous novel non-synonymous variant of unknown significance in AMMECR1 (c.G530A; p.G177D), a gene residing in the AMME disease locus. Transfected cell lines with the p.G177D mutation showed aberrant nuclear localisation patterns when compared with the wild type. Blood films revealed the presence of elliptocytes in the older brother. Conclusions Our study shows that a single missense mutation in AMMECR1 causes a phenotype of midface hypoplasia, mild intellectual disability and the presence of elliptocytes, previously reported as part of a contiguous gene deletion syndrome. Functional analysis confirms mutant-specific protein dysfunction. We conclude that AMMECR1 is a critical gene in the pathogenesis of AMME, causing midface hypoplasia and elliptocytosis and contributing to early speech and language delay, infantile hypotonia and hearing loss, and may play a role in dysmorphism, nephrocalcinosis and submucous cleft palate.
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Affiliation(s)
- Gaia Andreoletti
- Human Genetics & Genomic Medicine, University of Southampton, Duthie Building (Mailpoint 808), Southampton General Hospital, Southampton, UK
| | - Eleanor G Seaby
- Human Genetics & Genomic Medicine, University of Southampton, Duthie Building (Mailpoint 808), Southampton General Hospital, Southampton, UK
| | - Jennifer M Dewing
- Centre for Human Development, Stem Cells and Regeneration HDH, University of Southampton, IDS Building, Southampton General Hospital, Southampton, UK
| | - Ita O'Kelly
- Centre for Human Development, Stem Cells and Regeneration HDH, University of Southampton, IDS Building, Southampton General Hospital, Southampton, UK
| | - Katherine Lachlan
- Human Genetics & Genomic Medicine, University of Southampton, Duthie Building (Mailpoint 808), Southampton General Hospital, Southampton, UK.,Wessex Clinical Genetics Service, University Hospital Southampton NHS Foundation Trust, Princess Anne Hospital, Southampton, UK
| | - Rodney D Gilbert
- Wessex Regional Paediatric Nephro-Urology Service, Southampton Children's Hospital, Southampton, UK
| | - Sarah Ennis
- Human Genetics & Genomic Medicine, University of Southampton, Duthie Building (Mailpoint 808), Southampton General Hospital, Southampton, UK
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10
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Cooperative roles of glucose and asparagine-linked glycosylation in T-type calcium channel expression. Pflugers Arch 2016; 468:1837-1851. [DOI: 10.1007/s00424-016-1881-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 09/04/2016] [Accepted: 09/07/2016] [Indexed: 12/15/2022]
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11
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TASK-1 Regulates Apoptosis and Proliferation in a Subset of Non-Small Cell Lung Cancers. PLoS One 2016; 11:e0157453. [PMID: 27294516 PMCID: PMC4905626 DOI: 10.1371/journal.pone.0157453] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 05/31/2016] [Indexed: 12/29/2022] Open
Abstract
Lung cancer is the leading cause of cancer deaths worldwide; survival times are poor despite therapy. The role of the two-pore domain K+ (K2P) channel TASK-1 (KCNK3) in lung cancer is at present unknown. We found that TASK-1 is expressed in non-small cell lung cancer (NSCLC) cell lines at variable levels. In a highly TASK-1 expressing NSCLC cell line, A549, a characteristic pH- and hypoxia-sensitive non-inactivating K+ current was measured, indicating the presence of functional TASK-1 channels. Inhibition of TASK-1 led to significant depolarization in these cells. Knockdown of TASK-1 by siRNA significantly enhanced apoptosis and reduced proliferation in A549 cells, but not in weakly TASK-1 expressing NCI-H358 cells. Na+-coupled nutrient transport across the cell membrane is functionally coupled to the efflux of K+ via K+ channels, thus TASK-1 may potentially influence Na+-coupled nutrient transport. In contrast to TASK-1, which was not differentially expressed in lung cancer vs. normal lung tissue, we found the Na+-coupled nutrient transporters, SLC5A3, SLC5A6, and SLC38A1, transporters for myo-inositol, biotin and glutamine, respectively, to be significantly overexpressed in lung adenocarcinomas. In summary, we show for the first time that the TASK-1 channel regulates apoptosis and proliferation in a subset of NSCLC.
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Stead R, Musa MG, Bryant CL, Lanham SA, Johnston DA, Reynolds R, Torrens C, Fraser PA, Clough GF. Developmental conditioning of endothelium-derived hyperpolarizing factor-mediated vasorelaxation. J Hypertens 2016; 34:452-63; discussion 463. [PMID: 26682783 PMCID: PMC4732175 DOI: 10.1097/hjh.0000000000000833] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Revised: 10/26/2015] [Accepted: 11/20/2015] [Indexed: 01/13/2023]
Abstract
OBJECTIVES The endothelium maintains vascular homeostasis through the release of endothelium-derived relaxing factors (EDRF) and endothelium-derived hyperpolarization (EDH). The balance in EDH : EDRF is disturbed in cardiovascular disease and may also be susceptible to developmental conditioning through exposure to an adverse uterine environment to predispose to later risk of hypertension and vascular disease. METHODS Developmentally conditioned changes in EDH : EDRF signalling pathways were investigated in cremaster arterioles (18-32 μm diameter) and third-order mesenteric arteries of adult male mice offspring of dams fed either a fat-rich (high fat, HF, 45% energy from fat) or control (C, 10% energy from fat) diet. After weaning, offspring either continued on high fat or were placed on control diets to give four dietary groups (C/C, HF/C, C/HF, and HF/HF) and studied at 15 weeks of age. RESULTS EDH via intermediate (IKCa) and small (SKca) conductance calcium-activated potassium channels contributed less than 10% to arteriolar acetylcholine-induced relaxation in in-situ conditioned HF/C offspring compared with ∼60% in C/C (P < 0.01). The conditioned reduction in EDH signalling in HF/C offspring was reversed in offspring exposed to a high-fat diet both before and after weaning (HF/HF, 55%, P < 0.01 vs. HF/C). EDH signalling was unaffected in arterioles from C/HF offspring. The changes in EDH : EDRF were associated with altered endothelial cell expression and localization of IKCa channels. CONCLUSION This is the first evidence that EDH-mediated microvascular relaxation is susceptible to an adverse developmental environment through down-regulation of the IKCa signalling pathway. Conditioned offspring exposed to a 'second hit' (HF/HF) exhibit adaptive vascular mechanisms to preserve dilator function.
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Affiliation(s)
- Rebecca Stead
- Vascular Research Group
- Rebecca Stead and Moji G. Musa contributed equally to the writing of this article
| | - Moji G. Musa
- Vascular Research Group
- Rebecca Stead and Moji G. Musa contributed equally to the writing of this article
| | | | - Stuart A. Lanham
- Bone and Joint Research Group, Institute of Developmental Sciences
| | - David A. Johnston
- Faculty of Medicine, Biomedical Imaging Unit, University of Southampton, Southampton
| | | | | | - Paul A. Fraser
- Cardiovascular Division, BHF Centre of Research Excellence, School of Medicine, King's College London, London, United Kingdom
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Defaus S, Gupta P, Andreu D, Gutiérrez-Gallego R. Mammalian protein glycosylation--structure versus function. Analyst 2015; 139:2944-67. [PMID: 24779027 DOI: 10.1039/c3an02245e] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Carbohydrates fulfil many common as well as extremely important functions in nature. They show a variety of molecular displays--e.g., free mono-, oligo-, and polysaccharides, glycolipids, proteoglycans, glycoproteins, etc.--with particular roles and localizations in living organisms. Structure-specific peculiarities are so many and diverse that it becomes virtually impossible to cover them all from an analytical perspective. Hence this manuscript, focused on mammalian glycosylation, rather than a complete list of analytical descriptors or recognized functions for carbohydrate structures, comprehensively reviews three central issues in current glycoscience, namely (i) structural analysis of glycoprotein glycans, covering both classical and novel approaches for teasing out the structural puzzle as well as potential pitfalls of these processes; (ii) an overview of functions attributed to carbohydrates, covering from monosaccharide to complex, well-defined epitopes and full glycans, including post-glycosylational modifications, and (iii) recent technical advances allowing structural identification of glycoprotein glycans with simultaneous assignation of biological functions.
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Affiliation(s)
- S Defaus
- Department of Experimental and Health Sciences, Pompeu Fabra University, Barcelona Biomedical Research Park, 08003 Barcelona, Spain.
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Abstract
The Centre for Human Development, Stem Cells and Regeneration (CHDSCR) was founded in 2004 as a cross-disciplinary research and translational program within the Faculty of Medicine at the University of Southampton. The Centre undertakes fundamental research into early development and stem cells together with applied translational research for patient benefit. The Centre has vibrant and thriving multidisciplinary research programs that harness the translational strength of the Faculty together with an innovative Stem Cell PhD program, outstanding clinical infrastructure and enterprise to deliver on this vision.
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O'Kelly I. Endocytosis as a mode to regulate functional expression of two-pore domain potassium (K₂p) channels. Pflugers Arch 2014; 467:1133-42. [PMID: 25413469 PMCID: PMC4428836 DOI: 10.1007/s00424-014-1641-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2014] [Revised: 10/22/2014] [Accepted: 10/24/2014] [Indexed: 11/06/2022]
Abstract
Two-pore domain potassium (K2P) channels are implicated in an array of physiological and pathophysiological roles. As a result of their biophysical properties, these channels produce a background leak K+ current which has a direct effect on cellular membrane potential and activity. The regulation of potassium leak from cells through K2P channels is of critical importance to cell function, development and survival. Controlling the cell surface expression of these channels is one mode to regulate their function and is achieved through a balance between regulated channel delivery to and retrieval from the cell surface. Here, we explore the modes of retrieval of K2P channels from the plasma membrane and observe that K2P channels are endocytosed in both a clathrin-mediated and clathrin-independent manner. K2P channels use a variety of pathways and show altered internalisation and sorting in response to external cues. These pathways working in concert, equip the cell with a range of approaches to maintain steady state levels of channels and to respond rapidly should changes in channel density be required.
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Affiliation(s)
- Ita O'Kelly
- Human Development and Health, Centre for Human Development, Stem Cells and Regeneration, Faculty of Medicine, University of Southampton, Southampton, SO16 6YD, UK, I.M.O'
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Reorientation of the first signal-anchor sequence during potassium channel biogenesis at the Sec61 complex. Biochem J 2014; 456:297-309. [PMID: 24015703 PMCID: PMC3898203 DOI: 10.1042/bj20130100] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The majority of the polytopic proteins that are synthesized at the ER (endoplasmic reticulum) are integrated co-translationally via the Sec61 translocon, which provides lateral access for their hydrophobic TMs (transmembrane regions) to the phospholipid bilayer. A prolonged association between TMs of the potassium channel subunit, TASK-1 [TWIK (tandem-pore weak inwardly rectifying potassium channel)-related acid-sensitive potassium channel 1], and the Sec61 complex suggests that the ER translocon co-ordinates the folding/assembly of the TMs present in the nascent chain. The N-terminus of both TASK-1 and Kcv (potassium channel protein of chlorella virus), another potassium channel subunit of viral origin, has access to the N-glycosylation machinery located in the ER lumen, indicating that the Sec61 complex can accommodate multiple arrangements/orientations of TMs within the nascent chain, both in vitro and in vivo. Hence the ER translocon can provide the ribosome-bound nascent chain with a dynamic environment in which it can explore a range of different conformations en route to its correct transmembrane topology and final native structure. The Sec61 translocon provides an unexpectedly flexible and dynamic environment within which transmembrane regions of nascent polypeptides can be completely reoriented during the biosynthesis of multiple-spanning membrane proteins.
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Williams S, Bateman A, O'Kelly I. Altered expression of two-pore domain potassium (K2P) channels in cancer. PLoS One 2013; 8:e74589. [PMID: 24116006 PMCID: PMC3792113 DOI: 10.1371/journal.pone.0074589] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 08/03/2013] [Indexed: 01/31/2023] Open
Abstract
Potassium channels have become a focus in cancer biology as they play roles in cell behaviours associated with cancer progression, including proliferation, migration and apoptosis. Two-pore domain (K2P) potassium channels are background channels which enable the leak of potassium ions from cells. As these channels are open at rest they have a profound effect on cellular membrane potential and subsequently the electrical activity and behaviour of cells in which they are expressed. The K2P family of channels has 15 mammalian members and already 4 members of this family (K2P2.1, K2P3.1, K2P9.1, K2P5.1) have been implicated in cancer. Here we examine the expression of all 15 members of the K2P family of channels in a range of cancer types. This was achieved using the online cancer microarray database, Oncomine (www.oncomine.org). Each gene was examined across 20 cancer types, comparing mRNA expression in cancer to normal tissue. This analysis revealed all but 3 K2P family members (K2P4.1, K2P16.1, K2P18.1) show altered expression in cancer. Overexpression of K2P channels was observed in a range of cancers including breast, leukaemia and lung while more cancers (brain, colorectal, gastrointestinal, kidney, lung, melanoma, oesophageal) showed underexpression of one or more channels. K2P1.1, K2P3.1, K2P12.1, were overexpressed in a range of cancers. While K2P1.1, K2P3.1, K2P5.1, K2P6.1, K2P7.1 and K2P10.1 showed significant underexpression across the cancer types examined. This analysis supports the view that specific K2P channels may play a role in cancer biology. Their altered expression together with their ability to impact the function of other ion channels and their sensitivity to environmental stimuli (pO2, pH, glucose, stretch) makes understanding the role these channels play in cancer of key importance.
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Affiliation(s)
- Sarah Williams
- Human Development and Health, Centre for Human Development, Stem Cells and Regeneration, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Andrew Bateman
- Cancer Sciences, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
| | - Ita O'Kelly
- Human Development and Health, Centre for Human Development, Stem Cells and Regeneration, Faculty of Medicine, University of Southampton, Southampton, United Kingdom
- * E-mail: I.M.O'
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Mant A, Williams S, O'Kelly I. Acid sensitive background potassium channels K2P3.1 and K2P9.1 undergo rapid dynamin-dependent endocytosis. Channels (Austin) 2013; 7:288-302. [PMID: 23807092 DOI: 10.4161/chan.25120] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Acid-sensitive, two-pore domain potassium channels, K(2P)3.1 and K(2P)9.1, are implicated in cardiac and nervous tissue responses to hormones, neurotransmitters and drugs. K(2P)3.1 and K(2P)9.1 leak potassium from the cell at rest and directly impact membrane potential. Hence altering channel number on the cell surface drives changes in cellular electrical properties. The rate of K(2P)3.1 and K(2P)9.1 delivery to and recovery from the plasma membrane determines both channel number at the cell surface and potassium leak from cells. This study examines the endocytosis of K(2P)3.1 and K(2P)9.1. Plasma membrane biotinylation was used to follow the fate of internalized GFP-tagged rat K(2P)3.1 and K(2P)9.1 transiently expressed in HeLa cells. Confocal fluorescence images were analyzed using Imaris software, which revealed that both channels are endocytosed by a dynamin-dependent mechanism and over the course of 60 min, move progressively toward the nucleus. Endogenous endocytosis of human K(2P)3.1 and K(2P)9.1 was examined in the lung carcinoma cell line, A549. Endogenous channels are endocytosed over a similar time-scale to the channels expressed transiently in HeLa cells. These findings both validate the use of recombinant systems and identify an endogenous model system in which K(2P)3.1 and K(2P)9.1 trafficking can be further studied.
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Affiliation(s)
- Alexandra Mant
- Human Development and Health; Centre for Human Development, Stem Cells and Regeneration; Faculty of Medicine; University of Southampton; Southampton, UK
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