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Tetenborg S, Liss V, Breitsprecher L, Timonina K, Kotova A, Acevedo Harnecker AJ, Yuan C, Shihabeddin E, Ariakia F, Qin G, Chengzhi C, Dedek K, Zoidl G, Hensel M, O'Brien J. Intralumenal docking of connexin 36 channels in the ER isolates mistrafficked protein. J Biol Chem 2023; 299:105282. [PMID: 37742923 PMCID: PMC10637963 DOI: 10.1016/j.jbc.2023.105282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Revised: 08/30/2023] [Accepted: 09/05/2023] [Indexed: 09/26/2023] Open
Abstract
The intracellular domains of connexins are essential for the assembly of gap junctions. For connexin 36 (Cx36), the major neuronal connexin, it has been shown that a dysfunctional PDZ-binding motif interferes with electrical synapse formation. However, it is still unknown how this motif coordinates the transport of Cx36. In the present study, we characterize a phenotype of Cx36 mutants that lack a functional PDZ-binding motif using HEK293T cells as an expression system. We provide evidence that an intact PDZ-binding motif is critical for proper endoplasmic reticulum (ER) export of Cx36. Removing the PDZ-binding motif of Cx36 results in ER retention and the formation of multimembrane vesicles containing gap junction-like connexin aggregates. Using a combination of site-directed mutagenesis and electron micrographs, we reveal that these vesicles consist of Cx36 channels that docked prematurely in the ER. Our data suggest a model in which ER-retained Cx36 channels reshape the ER membrane into concentric whorls that are released into the cytoplasm.
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Affiliation(s)
| | - Viktoria Liss
- Department of Biology/Chemistry, iBiOs-Integrated Bioimaging Facility, CellNanOs - Center of Cellular Nanoanalytics, Osnabrück, Germany; Department of Microbiology, University of Osnabrück, Osnabrück, Germany
| | - Leonhard Breitsprecher
- Department of Biology/Chemistry, iBiOs-Integrated Bioimaging Facility, CellNanOs - Center of Cellular Nanoanalytics, Osnabrück, Germany; Department of Microbiology, University of Osnabrück, Osnabrück, Germany
| | - Ksenia Timonina
- Department of Biology, York University, Toronto, Ontario, Canada
| | - Anna Kotova
- Department of Biology, York University, Toronto, Ontario, Canada
| | | | - Chunxu Yuan
- Animal Navigation/Neurosensorics, Institute for Biology and Environmental Sciences, University of Oldenburg, Oldenburg, Germany
| | - Eyad Shihabeddin
- College of Optometry, University of Houston, Houston, Texas, USA; MD Anderson Cancer Center UTHealth Graduate School of Biomedical Sciences, Houston, Texas, USA
| | - Fatemeh Ariakia
- College of Optometry, University of Houston, Houston, Texas, USA
| | - Guoting Qin
- College of Optometry, University of Houston, Houston, Texas, USA
| | - Cai Chengzhi
- Department of Chemistry, University of Houston, Houston, Texas, USA
| | - Karin Dedek
- Animal Navigation/Neurosensorics, Institute for Biology and Environmental Sciences, University of Oldenburg, Oldenburg, Germany; Research Center Neurosensory Science, University of Oldenburg, Oldenburg, Germany
| | - Georg Zoidl
- Department of Microbiology, University of Osnabrück, Osnabrück, Germany
| | - Michael Hensel
- Department of Biology/Chemistry, iBiOs-Integrated Bioimaging Facility, CellNanOs - Center of Cellular Nanoanalytics, Osnabrück, Germany; Department of Microbiology, University of Osnabrück, Osnabrück, Germany
| | - John O'Brien
- College of Optometry, University of Houston, Houston, Texas, USA.
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Siu RCF, Kotova A, Timonina K, Zoidl C, Zoidl GR. Convergent NMDA receptor-Pannexin1 signaling pathways regulate the interaction of CaMKII with Connexin-36. Commun Biol 2021; 4:702. [PMID: 34103655 PMCID: PMC8187354 DOI: 10.1038/s42003-021-02230-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Accepted: 05/12/2021] [Indexed: 12/24/2022] Open
Abstract
Ca2+/calmodulin-dependent protein kinase II (CaMKII) binding and phosphorylation of mammalian connexin-36 (Cx36) potentiate electrical coupling. To explain the molecular mechanism of how Cx36 modifies plasticity at gap junctions, we investigated the roles of ionotropic N-methyl-D-aspartate receptors and pannexin1 (Panx1) channels in regulating Cx36 binding to CaMKII. Pharmacological interference and site-directed mutagenesis of protein interaction sites shows that NMDA receptor activation opens Cx36 channels, causing the Cx36- CaMKII binding complex to adopt a compact conformation. Ectopic Panx1 expression in a Panx1 knock-down cell line is required to restore CaMKII mediated opening of Cx36. Furthermore, blocking of Src-family kinase activation of Panx1 is sufficient to prevent the opening of Cx36 channels. Our research demonstrates that the efficacy of Cx36 channels requires convergent calcium-dependent signaling processes in which activation of ionotropic N-methyl-D-aspartate receptor, Src-family kinase, and Pannexin1 open Cx36. Our results add to the best of our knowledge a new twist to mounting evidence for molecular communication between these core components of electrical and chemical synapses.
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Affiliation(s)
- Ryan C F Siu
- Department of Biology, York University, Toronto, ON, Canada
- Center of Vision Research, York University, Toronto, ON, Canada
| | - Anna Kotova
- Department of Biology, York University, Toronto, ON, Canada
- Center of Vision Research, York University, Toronto, ON, Canada
| | - Ksenia Timonina
- Department of Biology, York University, Toronto, ON, Canada
- Center of Vision Research, York University, Toronto, ON, Canada
| | | | - Georg R Zoidl
- Department of Biology, York University, Toronto, ON, Canada.
- Center of Vision Research, York University, Toronto, ON, Canada.
- Department of Psychology, York University, Toronto, ON, Canada.
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Belik L, Prikhodko E, Chubar A, Semenova N, Bessmeltsev S, Gritsaev S, Kostroma I, Zhernyakova A, Kotova A, Maslennikova I, Ivolgin D, Enukashvily N. Transcription of the Wnt3a and Wnt5a genes, which contribute to osteoblastogenesis, is decreased in hematopoietic niche mesenchymal stromal cells of treated multiple myeloma patients. Cytotherapy 2021. [DOI: 10.1016/s1465324921003315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Kotova A, Timonina K, Zoidl GR. Endocytosis of Connexin 36 is Mediated by Interaction with Caveolin-1. Int J Mol Sci 2020; 21:E5401. [PMID: 32751343 PMCID: PMC7432810 DOI: 10.3390/ijms21155401] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Revised: 07/25/2020] [Accepted: 07/28/2020] [Indexed: 12/22/2022] Open
Abstract
The gap junctional protein connexin 36 (Cx36) has been co-purified with the lipid raft protein caveolin-1 (Cav-1). The relevance of an interaction between the two proteins is unknown. In this study, we explored the significance of Cav-1 interaction in the context of intracellular and membrane transport of Cx36. Coimmunoprecipitation assays and Förster resonance energy transfer analysis (FRET) were used to confirm the interaction between the two proteins in the Neuro 2a cell line. We found that the Cx36 and Cav-1 interaction was dependent on the intracellular calcium levels. By employing different microscopy techniques, we demonstrated that Cav-1 enhances the vesicular transport of Cx36. Pharmacological interventions coupled with cell surface biotinylation assays and FRET analysis revealed that Cav-1 regulates membrane localization of Cx36. Our data indicate that the interaction between Cx36 and Cav-1 plays a role in the internalization of Cx36 by a caveolin-dependent pathway.
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Affiliation(s)
- Anna Kotova
- Department of Biology, York University, Toronto, ON M3J 1P3, Canada; (A.K.); (K.T.)
| | - Ksenia Timonina
- Department of Biology, York University, Toronto, ON M3J 1P3, Canada; (A.K.); (K.T.)
| | - Georg R. Zoidl
- Department of Biology, York University, Toronto, ON M3J 1P3, Canada; (A.K.); (K.T.)
- Department of Psychology, York University, Toronto, ON M3J 1P3, Canada
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Roussos E, Kollmann P, Krupp N, Kotova A, Regoli L, Paranicas C, Mitchell DG, Krimigis SM, Hamilton D, Brandt P, Carbary J, Christon S, Dialynas K, Dandouras I, Hill ME, Ip WH, Jones GH, Livi S, Mauk BH, Palmaerts B, Roelof EC, Rymer A, Sergis N, Smith HT. A radiation belt of energetic protons located between Saturn and its rings. Science 2018; 362:362/6410/eaat1962. [DOI: 10.1126/science.aat1962] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2018] [Accepted: 09/05/2018] [Indexed: 11/03/2022]
Abstract
Saturn has a sufficiently strong dipole magnetic field to trap high-energy charged particles and form radiation belts, which have been observed outside its rings. Whether stable radiation belts exist near the planet and inward of the rings was previously unknown. The Cassini spacecraft’s Magnetosphere Imaging Instrument obtained measurements of a radiation belt that lies just above Saturn’s dense atmosphere and is decoupled from the rest of the magnetosphere by the planet’s A- to C-rings. The belt extends across the D-ring and comprises protons produced through cosmic ray albedo neutron decay and multiple charge-exchange reactions. These protons are lost to atmospheric neutrals and D-ring dust. Strong proton depletions that map onto features on the D-ring indicate a highly structured and diverse dust environment near Saturn.
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Kotova A, Elsukova L, Shumeev A, Levchuk K, Zolina T, Maslennikova I, Enukashvily N. Expansion of umbilical cord mesenchymal stem cells using xeno-free culture conditions and their viability in long-term shipping for clinical use. Cytotherapy 2018. [DOI: 10.1016/j.jcyt.2018.02.112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Enukashvily N, Levchuk K, Bagaeva V, Bogolyubov D, Bogolyubova I, Shumeev A, Zolina T, Kotova A, Maslennikova I, Artamonov A, Marchenko N, Mindukshev I, Kotkas I. Uncoated iron oxide nanoparticles as a tool for human mesenchymal stromal cells labelling in vivo. Cytotherapy 2018. [DOI: 10.1016/j.jcyt.2018.02.089] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Kollmann P, Roussos E, Kotova A, Cooper JF, Mitchell DG, Krupp N, Paranicas C. MeV proton flux predictions near Saturn's D ring. J Geophys Res Space Phys 2015; 120:8586-8602. [PMID: 27812437 PMCID: PMC5066344 DOI: 10.1002/2015ja021621] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 09/11/2015] [Accepted: 09/22/2015] [Indexed: 06/06/2023]
Abstract
Radiation belts of MeV protons have been observed just outward of Saturn's main rings. During the final stages of the mission, the Cassini spacecraft will pass through the gap between the main rings and the planet. Based on how the known radiation belts of Saturn are formed, it is expected that MeV protons will be present in this gap and also bounce through the tenuous D ring right outside the gap. At least one model has suggested that the intensity of MeV protons near the planet could be much larger than in the known belts. We model this inner radiation belt using a technique developed earlier to understand Saturn's known radiation belts. We find that the inner belt is very different from the outer belts in the sense that its intensity is limited by the densities of the D ring and Saturn's upper atmosphere, not by radial diffusion and satellite absorption. The atmospheric density is relatively well constrained by EUV occultations. Based on that we predict an intensity in the gap region that is well below that of the known belts. It is more difficult to do the same for the region magnetically connected to the D ring since its density is poorly constrained. We find that the intensity in this region can be comparable to the known belts. Such intensities pose no hazard to the mission since Cassini would only experience these fluxes on timescales of minutes but might affect scientific measurements by decreasing the signal-to-contamination ratio of instruments.
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Affiliation(s)
- P. Kollmann
- The Johns Hopkins UniversityApplied Physics LaboratoryLaurelMarylandUSA
| | - E. Roussos
- Max Planck Institute for Solar System ResearchGöttingenGermany
| | - A. Kotova
- Max Planck Institute for Solar System ResearchGöttingenGermany
- Université Paul Sabatier Toulouse IIIUPS‐OMP, IRAPToulouseFrance
| | - J. F. Cooper
- NASA Goddard Space Flight CenterGreenbeltMarylandUSA
| | - D. G. Mitchell
- The Johns Hopkins UniversityApplied Physics LaboratoryLaurelMarylandUSA
| | - N. Krupp
- Max Planck Institute for Solar System ResearchGöttingenGermany
| | - C. Paranicas
- The Johns Hopkins UniversityApplied Physics LaboratoryLaurelMarylandUSA
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