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Abd El-Aziz TM, Kaur A, Shapiro MS, Stockand JD, Archer CR. Optogenetic Control of PIP2 Interactions Shaping ENaC Activity. Int J Mol Sci 2022; 23:ijms23073884. [PMID: 35409240 PMCID: PMC8998630 DOI: 10.3390/ijms23073884] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [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: 03/14/2022] [Accepted: 03/29/2022] [Indexed: 02/06/2023] Open
Abstract
The activity of the epithelial Na+ Channel (ENaC) is strongly dependent on the membrane phospholipid phosphatidylinositol 4,5-bisphosphate (PIP2). PIP2 binds two distinct cationic clusters within the N termini of β- and γ-ENaC subunits (βN1 and γN2). The affinities of these sites were previously determined using short synthetic peptides, yet their role in sensitizing ENaC to changes in PIP2 levels in the cellular system is not well established. We addressed this question by comparing the effects of PIP2 depletion and recovery on ENaC channel activity and intracellular Na+ levels [Na+]i. We tested effects on ENaC activity with mutations to the PIP2 binding sites using the optogenetic system CIBN/CRY2-OCRL to selectively deplete PIP2. We monitored changes of [Na+]i by measuring the fluorescent Na+ indicator, CoroNa Green AM, and changes in channel activity by performing patch clamp electrophysiology. Whole cell patch clamp measurements showed a complete lack of response to PIP2 depletion and recovery in ENaC with mutations to βN1 or γN2 or both sites, compared to wild type ENaC. Whereas mutant βN1 also had no change in CoroNa Green fluorescence in response to PIP2 depletion, γN2 did have reduced [Na+]i, which was explained by having shorter CoroNa Green uptake and half-life. These results suggest that CoroNa Green measurements should be interpreted with caution. Importantly, the electrophysiology results show that the βN1 and γN2 sites on ENaC are each necessary to permit maximal ENaC activity in the presence of PIP2.
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Affiliation(s)
- Tarek Mohamed Abd El-Aziz
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78228, USA; (T.M.A.E.-A.); (M.S.S.); (J.D.S.)
- Faculty of Science, Zoology Department, Minia University, El-Minia 61519, Egypt
| | - Amanpreet Kaur
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA;
| | - Mark S. Shapiro
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78228, USA; (T.M.A.E.-A.); (M.S.S.); (J.D.S.)
| | - James D. Stockand
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78228, USA; (T.M.A.E.-A.); (M.S.S.); (J.D.S.)
| | - Crystal R. Archer
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX 78228, USA; (T.M.A.E.-A.); (M.S.S.); (J.D.S.)
- Correspondence:
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Rajakani R, Sellamuthu G, Ishikawa T, Ahmed HAI, Bharathan S, Kumari K, Shabala L, Zhou M, Chen ZH, Shabala S, Venkataraman G. Reduced apoplastic barriers in tissues of shoot-proximal rhizomes of Oryza coarctata are associated with Na+ sequestration. J Exp Bot 2022; 73:998-1015. [PMID: 34606587 DOI: 10.1093/jxb/erab440] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 09/25/2021] [Indexed: 06/13/2023]
Abstract
Oryza coarctata is the only wild rice species with significant salinity tolerance. The present work examines the role of the substantial rhizomatous tissues of O. coarctata in conferring salinity tolerance. Transition to an erect phenotype (shoot emergence) from prostrate growth of rhizome tissues is characterized by marked lignification and suberization of supporting sclerenchymatous tissue, epidermis, and bundle sheath cells in aerial shoot-proximal nodes and internodes in O. coarctata. With salinity, however, aerial shoot-proximal internodal tissues show reductions in lignification and suberization, most probably related to re-direction of carbon flux towards synthesis of the osmporotectant proline. Concurrent with hypolignification and reduced suberization, the aerial rhizomatous biomass of O. coarctata appears to have evolved mechanisms to store Na+ in these specific tissues under salinity. This was confirmed by histochemical staining, quantitative real-time reverse transcription-PCR expression patterns of genes involved in lignification/suberization, Na+ and K+ contents of internodal tissues, as well as non-invasive microelectrode ion flux measurements of NaCl-induced net Na+, K+, and H+ flux profiles of aerial nodes were determined. In O. coarctata, aerial proximal internodes appear to act as 'traffic controllers', sending required amounts of Na+ and K+ into developing leaves for osmotic adjustment and turgor-driven growth, while more deeply positioned internodes assume a Na+ buffering/storage role.
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Affiliation(s)
- Raja Rajakani
- Plant Molecular Biology Laboratory, M.S. Swaminathan Research Foundation, III Cross Street, Taramani Institutional Area, Chennai 600 113, India
| | - Gothandapani Sellamuthu
- Plant Molecular Biology Laboratory, M.S. Swaminathan Research Foundation, III Cross Street, Taramani Institutional Area, Chennai 600 113, India
- Forest Molecular Entomology Laboratory, Excellent Team for Mitigation (ETM), Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Prague-16500, Czech Republic
| | - Tetsuya Ishikawa
- Tasmanian Institute of Agriculture, College of Science and Engineering, University of Tasmania, Private Bag 98, Hobart, Tas 7001, Australia
| | - Hassan Ahmed Ibraheem Ahmed
- Tasmanian Institute of Agriculture, College of Science and Engineering, University of Tasmania, Private Bag 98, Hobart, Tas 7001, Australia
- Department of Botany, Faculty of Science, Port Said University, Port Said 42522, Egypt
| | - Subhashree Bharathan
- School of Chemical and Biotechnology, SASTRA Deemed to be University, Thirumalaisamudram, Thanjavur-613401, Tamil Nadu, India
| | - Kumkum Kumari
- Plant Molecular Biology Laboratory, M.S. Swaminathan Research Foundation, III Cross Street, Taramani Institutional Area, Chennai 600 113, India
| | - Lana Shabala
- Tasmanian Institute of Agriculture, College of Science and Engineering, University of Tasmania, Private Bag 98, Hobart, Tas 7001, Australia
| | - Meixue Zhou
- Tasmanian Institute of Agriculture, College of Science and Engineering, University of Tasmania, Private Bag 98, Hobart, Tas 7001, Australia
| | - Zhong-Hua Chen
- School of Science, Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, 2751, Australia
| | - Sergey Shabala
- Tasmanian Institute of Agriculture, College of Science and Engineering, University of Tasmania, Private Bag 98, Hobart, Tas 7001, Australia
- International Research Centre for Environmental Membrane Biology, Foshan University, Foshan 528000, China
| | - Gayatri Venkataraman
- Plant Molecular Biology Laboratory, M.S. Swaminathan Research Foundation, III Cross Street, Taramani Institutional Area, Chennai 600 113, India
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Iamshanova O, Mariot P, Lehen'kyi V, Prevarskaya N. Comparison of fluorescence probes for intracellular sodium imaging in prostate cancer cell lines. Eur Biophys J 2016; 45:765-777. [PMID: 27660079 PMCID: PMC5045488 DOI: 10.1007/s00249-016-1173-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [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: 02/02/2016] [Revised: 07/23/2016] [Accepted: 09/02/2016] [Indexed: 10/25/2022]
Abstract
Sodium (Na+) ions are known to regulate many signaling pathways involved in both physiological and pathological conditions. In particular, alterations in intracellular concentrations of Na+ and corresponding changes in membrane potential are known to be major actors of cancer progression to metastatic phenotype. Though the functionality of Na+ channels and the corresponding Na+ currents can be investigated using the patch-clamp technique, the latter is rather invasive and a technically difficult method to study intracellular Na+ transients compared to Na+ fluorescence imaging. Despite the fact that Na+ signaling is considered an important controller of cancer progression, only few data using Na+ imaging approaches are available so far, suggesting the persisting challenge within the scientific community. In this study, we describe in detail the approach for application of Na+ imaging technique to measure intracellular Na+ variations in human prostate cancer cells. Accordingly, we used three Na+-specific fluorescent dyes-Na+-binding benzofuran isophthalate (SBFI), CoroNa™ Green (Corona) and Asante NaTRIUM Green-2 (ANG-2). These dyes have been assessed for optimal loading conditions, dissociation constant and working range after different calibration methods, and intracellular Na+ sensitivity, in order to determine which probe can be considered as the most reliable to visualize Na+ fluctuations in vitro.
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Affiliation(s)
- Oksana Iamshanova
- Inserm U1003, Laboratory of Excellence, Ion Channels Science and Therapeutics, Equipe Labellisée par la Ligue Nationale Contre le Cancer, SIRIC ONCOLille, Université des Sciences et Technologies de Lille, 59656, Villeneuve d'Ascq, France
| | - Pascal Mariot
- Inserm U1003, Laboratory of Excellence, Ion Channels Science and Therapeutics, Equipe Labellisée par la Ligue Nationale Contre le Cancer, SIRIC ONCOLille, Université des Sciences et Technologies de Lille, 59656, Villeneuve d'Ascq, France
| | - V'yacheslav Lehen'kyi
- Inserm U1003, Laboratory of Excellence, Ion Channels Science and Therapeutics, Equipe Labellisée par la Ligue Nationale Contre le Cancer, SIRIC ONCOLille, Université des Sciences et Technologies de Lille, 59656, Villeneuve d'Ascq, France
| | - Natalia Prevarskaya
- Inserm U1003, Laboratory of Excellence, Ion Channels Science and Therapeutics, Equipe Labellisée par la Ligue Nationale Contre le Cancer, SIRIC ONCOLille, Université des Sciences et Technologies de Lille, 59656, Villeneuve d'Ascq, France.
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