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Holm CM, Topaktas AB, Dannesboe J, Pless SA, Heusser SA. Dynamic conformational changes of acid-sensing ion channels in different desensitizing conditions. Biophys J 2024:S0006-3495(24)00240-6. [PMID: 38549370 DOI: 10.1016/j.bpj.2024.03.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2023] [Revised: 02/21/2024] [Accepted: 03/26/2024] [Indexed: 04/18/2024] Open
Abstract
Acid-sensing ion channels (ASICs) are proton-gated cation channels that contribute to fast synaptic transmission and have roles in fear conditioning and nociception. Apart from activation at low pH, ASIC1a also undergoes several types of desensitization, including acute desensitization, which terminates activation; steady-state desensitization, which occurs at sub-activating proton concentrations and limits subsequent activation; and tachyphylaxis, which results in a progressive decrease in response during a series of activations. Structural insights from a desensitized state of ASIC1 have provided great spatial detail, but dynamic insights into conformational changes in different desensitizing conditions are largely missing. Here, we use electrophysiology and voltage-clamp fluorometry to follow the functional changes of the pore along with conformational changes at several positions in the extracellular and upper transmembrane domain via cysteine-labeled fluorophores. Acute desensitization terminates activation in wild type, but introducing an N414K mutation in the β11-12 linker of mouse ASIC1a interfered with this process. The mutation also affected steady-state desensitization and led to pronounced tachyphylaxis. Although the extracellular domain of this mutant remained sensitive to pH and underwent pH-dependent conformational changes, these conformational changes did not necessarily lead to desensitization. N414K-containing channels also remained sensitive to a known peptide modulator that increases steady-state desensitization, indicating that the mutation only reduced, but not precluded, desensitization. Together, this study contributes to our understanding of the fundamental properties of ASIC1a desensitization, emphasizing the complex interplay between the conformational changes of the extracellular domain and the pore during channel activation and desensitization.
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Affiliation(s)
- Caroline Marcher Holm
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Asli B Topaktas
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark; Department of Cellular and Molecular Medicine, University of Copenhagen, Copenhagen, Denmark
| | - Johs Dannesboe
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark; Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Stephan A Pless
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Stephanie A Heusser
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
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Forrester EA, Benítez-Angeles M, Redford KE, Rosenbaum T, Abbott GW, Barrese V, Dora K, Albert AP, Dannesboe J, Salles-Crawley I, Jepps TA, Greenwood IA. Crucial role for Sodium Hydrogen Exchangers in SGLT2 inhibitor-induced arterial relaxations. bioRxiv 2023:2023.12.05.570303. [PMID: 38116028 PMCID: PMC10729745 DOI: 10.1101/2023.12.05.570303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2023]
Abstract
Introduction Sodium dependent glucose transporter 2 (SGLT2 or SLC5A2) inhibitors effectively lower blood glucose and are also approved treatments for heart failure independent of raised glucose. One component of the cardioprotective effect is reduced cardiac afterload but the mechanisms underlying peripheral relaxation are ill defined and variable. We speculated that SGLT2 inhibitors promoted arterial relaxation via the release of the potent vasodilator calcitonin gene-related peptide (CGRP) from sensory nerves independent of glucose transport. Experimental approach The functional effects of SGLT2 inhibitors (dapagliflozin, empagliflozin, ertugliflozin) and the sodium/hydrogen exchanger 1 (NHE1) blocker cariporide were determined on pre-contracted mesenteric and renal arteries from male Wistar rats using Wire-Myography. SGLT2, NHE1, CGRP and TRPV1 expression in both arteries was determined by Western blot and immunohistochemistry. Kv7.4/5/KCNE4 and TRPV1 currents were measured in the presence and absence of dapagliflozin and empagliflozin. Results All SGLT2 inhibitors produced a concentration dependent relaxation (1µM-100µM) of mesenteric arteries that was considerably greater than in renal arteries. Cariporide relaxed mesenteric arteries but not renal arteries. Immunohistochemistry with TRPV1 and CGRP antibodies revealed a dense innervation of sensory nerves in mesenteric arteries that was absent in renal arteries. Consistent with a greater sensory nerve component, the TRPV1 agonist capsaicin produced significantly greater relaxations in mesenteric arteries compared to renal arteries. Relaxations to dapagliflozin, empagliflozin and cariporide were attenuated by incubation with the CGRP receptor antagonist BIBN-4096, the Kv7 blocker linopirdine and the TRPV1 antagonist AMG-517 as well as by depletion of neuronal CGRP. Neither dapagliflozin nor empagliflozin directly activated heterologously expressed TRPV1 channels or Kv7 channels. Strikingly, only NHE1 colocalised with TRPV1 in sensory nerves, and cariporide pre-application prevented the relaxant response to SGLT2 inhibitors. Conclusions SGLT2 inhibitors relax mesenteric arteries by a novel mechanism involving the release of CGRP from sensory nerves following inhibition of the Na + /H + exchanger.
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Czaplinska D, Ialchina R, Andersen HB, Yao J, Stigliani A, Dannesboe J, Flinck M, Chen X, Mitrega J, Gnosa SP, Dmytriyeva O, Alves F, Napp J, Sandelin A, Pedersen SF. Crosstalk between tumor acidosis, p53 and extracellular matrix regulates pancreatic cancer aggressiveness. Int J Cancer 2023; 152:1210-1225. [PMID: 36408933 PMCID: PMC10108304 DOI: 10.1002/ijc.34367] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 10/14/2022] [Accepted: 11/07/2022] [Indexed: 11/22/2022]
Abstract
Pancreatic ductal adenocarcinoma (PDAC) is an extremely aggressive malignancy with minimal treatment options and a global rise in prevalence. PDAC is characterized by frequent driver mutations including KRAS and TP53 (p53), and a dense, acidic tumor microenvironment (TME). The relation between genotype and TME in PDAC development is unknown. Strikingly, when wild type (WT) Panc02 PDAC cells were adapted to growth in an acidic TME and returned to normal pH to mimic invasive cells escaping acidic regions, they displayed a strong increase of aggressive traits such as increased growth in 3-dimensional (3D) culture, adhesion-independent colony formation and invasive outgrowth. This pattern of acidosis-induced aggressiveness was observed in 3D spheroid culture as well as upon organotypic growth in matrigel, collagen-I and combination thereof, mimicking early and later stages of PDAC development. Acid-adaptation-induced gain of cancerous traits was further increased by p53 knockout (KO), but only in specific extracellular matrix (ECM) compositions. Akt- and Transforming growth factor-β (TGFβ) signaling, as well as expression of the Na+ /H+ exchanger NHE1, were increased by acid adaptation. Whereas Akt inhibition decreased spheroid growth regardless of treatment and genotype, stimulation with TGFβI increased growth of WT control spheroids, and inhibition of TGFβ signaling tended to limit growth under acidic conditions only. Our results indicate that a complex crosstalk between tumor acidosis, ECM composition and genotype contributes to PDAC development. The findings may guide future strategies for acidosis-targeted therapies.
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Affiliation(s)
- Dominika Czaplinska
- Section for Cell Biology and Physiology, Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Renata Ialchina
- Section for Cell Biology and Physiology, Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Henriette Berg Andersen
- Section for Cell Biology and Physiology, Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Jiayi Yao
- Section for Computational and RNA Biology, Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark.,Biotech Research and Innovation Centre (BRIC), Faculty of Health, University of Copenhagen, Copenhagen, Denmark
| | - Arnaud Stigliani
- Section for Computational and RNA Biology, Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark.,Biotech Research and Innovation Centre (BRIC), Faculty of Health, University of Copenhagen, Copenhagen, Denmark
| | - Johs Dannesboe
- Section for Cell Biology and Physiology, Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Mette Flinck
- Section for Cell Biology and Physiology, Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Xiaoming Chen
- Section for Cell Biology and Physiology, Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Jakub Mitrega
- Max-Planck-Institute for Multidisciplinary Sciences, Goettingen, Germany.,Institute for Diagnostic and Interventional Radiology, University Medical Center Goettingen, Goettingen, Germany
| | - Sebastian Peter Gnosa
- Biotech Research and Innovation Centre (BRIC), Faculty of Health, University of Copenhagen, Copenhagen, Denmark
| | - Oksana Dmytriyeva
- Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health, University of Copenhagen, Copenhagen, Denmark
| | - Frauke Alves
- Max-Planck-Institute for Multidisciplinary Sciences, Goettingen, Germany.,Institute for Diagnostic and Interventional Radiology, University Medical Center Goettingen, Goettingen, Germany.,Clinic of Haematology and Medical Oncology, University Medical Center Goettingen, Goettingen, Germany
| | - Joanna Napp
- Max-Planck-Institute for Multidisciplinary Sciences, Goettingen, Germany.,Institute for Diagnostic and Interventional Radiology, University Medical Center Goettingen, Goettingen, Germany.,Clinic of Haematology and Medical Oncology, University Medical Center Goettingen, Goettingen, Germany
| | - Albin Sandelin
- Section for Computational and RNA Biology, Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark.,Biotech Research and Innovation Centre (BRIC), Faculty of Health, University of Copenhagen, Copenhagen, Denmark
| | - Stine Falsig Pedersen
- Section for Cell Biology and Physiology, Department of Biology, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
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