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Conner GE. NADPH Alters DUOX1 Calcium Responsiveness. Redox Biol 2024; 75:103251. [PMID: 38936256 DOI: 10.1016/j.redox.2024.103251] [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: 05/23/2024] [Revised: 06/14/2024] [Accepted: 06/20/2024] [Indexed: 06/29/2024] Open
Abstract
Hydrogen peroxide is a key element in redox signaling and in setting cellular redox tone. DUOX1 and DUOX2, that directly synthesize hydrogen peroxide, are the most abundant NADPH oxidase transcripts in most epithelia. DUOX1 and DUOX2 hydrogen peroxide synthesis is regulated by intracellular calcium transients and thus cells can respond to signals and initiate responses by increasing cellular hydrogen peroxide synthesis. Nevertheless, many details of their enzymatic regulation are still unexplored. DUOX1 and DUOXA1 were expressed in HEK293T cells and activity was studied in homogenates and membrane fractions. When DUOX1 homogenates or membranes were pre-incubated in NADPH and started with addition of Ca2+, to mimic intracellular activation, progress curves were distinctly different from those pre-incubated in Ca2+ and started with NADPH. The Ca2+ EC50 for DUOX1's initial rate when pre-incubated in Ca2+, was three orders of magnitude lower (EC50 ∼ 10-6 M) than with preincubation in NADPH (EC50 ∼ 10-3 M). In addition, activity was several fold lower with Ca2+ start. Identical results were obtained using homogenates and membrane fractions. The data suggested that DUOX1 Ca2+ binding in expected physiological signaling conditions only slowly leads to maximal hydrogen peroxide synthesis and that full hydrogen peroxide synthesis activity in vivo only can occur when encountering extremely high concentration Ca2+ signals. Thus, a complex interplay of intracellular NADPH and Ca2+ concentrations regulate DUOX1 over a wide extent and may limit DUOX1 activity to a restricted range and spatial distribution.
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Affiliation(s)
- Gregory E Conner
- Department of Cell Biology, University of Miami Miller School of Medicine, 1600 NW 10th Avenue, Miami Fl, 33136, USA.
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Szanto TG, Feher A, Korpos E, Gyöngyösi A, Kállai J, Mészáros B, Ovari K, Lányi Á, Panyi G, Varga Z. 5-Chloro-2-Guanidinobenzimidazole (ClGBI) Is a Non-Selective Inhibitor of the Human H V1 Channel. Pharmaceuticals (Basel) 2023; 16:ph16050656. [PMID: 37242439 DOI: 10.3390/ph16050656] [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: 03/22/2023] [Revised: 04/13/2023] [Accepted: 04/24/2023] [Indexed: 05/28/2023] Open
Abstract
5-chloro-2-guanidinobenzimidazole (ClGBI), a small-molecule guanidine derivative, is a known effective inhibitor of the voltage-gated proton (H+) channel (HV1, Kd ≈ 26 μM) and is widely used both in ion channel research and functional biological assays. However, a comprehensive study of its ion channel selectivity determined by electrophysiological methods has not been published yet. The lack of selectivity may lead to incorrect conclusions regarding the role of hHv1 in physiological or pathophysiological responses in vitro and in vivo. We have found that ClGBI inhibits the proliferation of lymphocytes, which absolutely requires the functioning of the KV1.3 channel. We, therefore, tested ClGBI directly on hKV1.3 using a whole-cell patch clamp and found an inhibitory effect similar in magnitude to that seen on hHV1 (Kd ≈ 72 μM). We then further investigated ClGBI selectivity on the hKV1.1, hKV1.4-IR, hKV1.5, hKV10.1, hKV11.1, hKCa3.1, hNaV1.4, and hNaV1.5 channels. Our results show that, besides HV1 and KV1.3, all other off-target channels were inhibited by ClGBI, with Kd values ranging from 12 to 894 μM. Based on our comprehensive data, ClGBI has to be considered a non-selective hHV1 inhibitor; thus, experiments aiming at elucidating the significance of these channels in physiological responses have to be carefully evaluated.
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Affiliation(s)
- Tibor G Szanto
- Department of Biophysics & Cell Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Adam Feher
- Department of Biophysics & Cell Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Eva Korpos
- Department of Biophysics & Cell Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
- ELKH-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Adrienn Gyöngyösi
- Department of Immunology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Judit Kállai
- ELKH-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
- Department of Immunology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Beáta Mészáros
- Department of Biophysics & Cell Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Krisztian Ovari
- Department of Biophysics & Cell Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Árpád Lányi
- Department of Immunology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Gyorgy Panyi
- Department of Biophysics & Cell Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
- ELKH-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Zoltan Varga
- Department of Biophysics & Cell Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
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Cozzolino M, Gyöngyösi A, Korpos E, Gogolak P, Naseem MU, Kállai J, Lanyi A, Panyi G. The Voltage-Gated Hv1 H+ Channel Is Expressed in Tumor-Infiltrating Myeloid-Derived Suppressor Cells. Int J Mol Sci 2023; 24:ijms24076216. [PMID: 37047188 PMCID: PMC10094655 DOI: 10.3390/ijms24076216] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Revised: 03/20/2023] [Accepted: 03/22/2023] [Indexed: 03/29/2023] Open
Abstract
Myeloid-derived suppressor cells (MDSCs) are key determinants of the immunosuppressive microenvironment in tumors. As ion channels play key roles in the physiology/pathophysiology of immune cells, we aimed at studying the ion channel repertoire in tumor-derived polymorphonuclear (PMN-MDSC) and monocytic (Mo-MDSC) MDSCs. Subcutaneous tumors in mice were induced by the Lewis lung carcinoma cell line (LLC). The presence of PMN-MDSC (CD11b+/Ly6G+) and Mo-MDSCs (CD11b+/Ly6C+) in the tumor tissue was confirmed using immunofluorescence microscopy and cells were identified as CD11b+/Ly6G+ PMN-MDSCs and CD11b+/Ly6C+/F4/80−/MHCII− Mo-MDSCs using flow cytometry and sorting. The majority of the myeloid cells infiltrating the LLC tumors were PMN-MDSC (~60%) as compared to ~10% being Mo-MDSCs. We showed that PMN- and Mo-MDSCs express the Hv1 H+ channel both at the mRNA and at the protein level and that the biophysical and pharmacological properties of the whole-cell currents recapitulate the hallmarks of Hv1 currents: ~40 mV shift in the activation threshold of the current per unit change in the extracellular pH, high H+ selectivity, and sensitivity to the Hv1 inhibitor ClGBI. As MDSCs exert immunosuppression mainly by producing reactive oxygen species which is coupled to Hv1-mediated H+ currents, Hv1 might be an attractive target for inhibition of MDSCs in tumors.
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Affiliation(s)
- Marco Cozzolino
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (M.C.); (E.K.); (M.U.N.)
| | - Adrienn Gyöngyösi
- Department of Immunology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (A.G.); (P.G.); (J.K.); (A.L.)
| | - Eva Korpos
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (M.C.); (E.K.); (M.U.N.)
- ELKH-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Peter Gogolak
- Department of Immunology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (A.G.); (P.G.); (J.K.); (A.L.)
| | - Muhammad Umair Naseem
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (M.C.); (E.K.); (M.U.N.)
| | - Judit Kállai
- Department of Immunology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (A.G.); (P.G.); (J.K.); (A.L.)
- ELKH-DE Cell Biology and Signaling Research Group, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Arpad Lanyi
- Department of Immunology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (A.G.); (P.G.); (J.K.); (A.L.)
| | - Gyorgy Panyi
- Department of Biophysics and Cell Biology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary; (M.C.); (E.K.); (M.U.N.)
- Correspondence: ; Tel.: +36-52-352201
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Conner GE. Regulation of dual oxidase hydrogen peroxide synthesis results in an epithelial respiratory burst. Redox Biol 2021; 41:101931. [PMID: 33743241 PMCID: PMC8010520 DOI: 10.1016/j.redox.2021.101931] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 02/19/2021] [Accepted: 03/01/2021] [Indexed: 12/23/2022] Open
Abstract
Redox status is a central determinant of cellular activities and redox imbalance is correlated with numerous diseases. NADPH oxidase activity results in formation of H2O2, that, in turn, sets cellular redox status, a key regulator of cellular homeostasis and responses to external stimuli. Hydrogen peroxide metabolism regulates cell redox status by driving changes in protein cysteine oxidation often via cycling of thioredoxin/peroxiredoxin and glutathione; however, regulation of enzymes controlling synthesis and utilization of H2O2 is not understood beyond broad outlines. The data presented here show that calcium-stimulated epithelial Duox H2O2 synthesis is transient, independent of intracellular calcium renormalization, H2O2 scavenging by antioxidant enzymes, or substrate depletion. The data support existence of a separate mechanism that restricts epithelial H2O2 synthesis to a burst and prevents harmful changes in redox tone following continuous stimulation. Elucidation of this H2O2 synthesis tempering mechanism is key to understanding cellular redox regulation and control of downstream effectors, and this observation provides a starting point for investigation of the mechanism that controls H2O2-mediated increases in redox tone. DUOX1 and DUOX2 H2O2 synthesis decreases after calcium stimulation even in the continued presence of elevated calcium. Decreasing DUOX1 and DUOX2 activity in elevated calcium is not due to substrate depletion or assay limitations. Calcium activation of DUOX1 and DUOX2 H2O2 synthesis results in a respiratory burst independent of calcium renormalization. The data support a mechanism that limits Duox H2O2 synthesis in the presence of continually elevated calcium stimulation.
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Affiliation(s)
- Gregory E Conner
- Department of Cell Biology, University of Miami Miller School of Medicine, 1600 NW 10(th) Avenue, Miami, Fl, 33136, USA.
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