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Light inactivation of water transport and protein–protein interactions of aquaporin–Killer Red chimeras

Aquaporins (AQPs) have a broad range of cellular and organ functions; however, nontoxic inhibitors of AQP water transport are not available. Here, we applied chromophore-assisted light inactivation (CALI) to inhibit the water permeability of AQP1, and of two AQP4 isoforms (M1 and M23), one of which...

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Autores principales: Baumgart, Florian, Rossi, Andrea, Verkman, A.S.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The Rockefeller University Press 2012
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3250104/
https://www.ncbi.nlm.nih.gov/pubmed/22200949
http://dx.doi.org/10.1085/jgp.201110712
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author Baumgart, Florian
Rossi, Andrea
Verkman, A.S.
author_facet Baumgart, Florian
Rossi, Andrea
Verkman, A.S.
author_sort Baumgart, Florian
collection PubMed
description Aquaporins (AQPs) have a broad range of cellular and organ functions; however, nontoxic inhibitors of AQP water transport are not available. Here, we applied chromophore-assisted light inactivation (CALI) to inhibit the water permeability of AQP1, and of two AQP4 isoforms (M1 and M23), one of which (M23) forms aggregates at the cell plasma membrane. Chimeras containing Killer Red (KR) and AQPs were generated with linkers of different lengths. Osmotic water permeability of cells expressing KR/AQP chimeras was measured from osmotic swelling–induced dilution of cytoplasmic chloride, which was detected using a genetically encoded chloride-sensing fluorescent protein. KR-AQP1 red fluorescence was bleached rapidly (∼10% per second) by wide-field epifluorescence microscopy. After KR bleaching, KR-AQP1 water permeability was reduced by up to 80% for the chimera with the shortest linker. Remarkably, CALI-induced reduction in AQP4-KR water permeability was approximately twice as efficient for the aggregate-forming M23 isoform; this suggests intermolecular CALI, which was confirmed by native gel electrophoresis on cells coexpressing M23-AQP4-KR and myc-tagged M23-AQP4. CALI also disrupted the interaction of AQP4 with a neuromyelitis optica autoantibody directed against an extracellular epitope on AQP4. CALI thus permits rapid, spatially targeted and irreversible reduction in AQP water permeability and interactions in live cells. Our data also support the utility of CALI to study protein–protein interactions as well as other membrane transporters and receptors.
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spelling pubmed-32501042012-07-01 Light inactivation of water transport and protein–protein interactions of aquaporin–Killer Red chimeras Baumgart, Florian Rossi, Andrea Verkman, A.S. J Gen Physiol Tutorial Research Article Aquaporins (AQPs) have a broad range of cellular and organ functions; however, nontoxic inhibitors of AQP water transport are not available. Here, we applied chromophore-assisted light inactivation (CALI) to inhibit the water permeability of AQP1, and of two AQP4 isoforms (M1 and M23), one of which (M23) forms aggregates at the cell plasma membrane. Chimeras containing Killer Red (KR) and AQPs were generated with linkers of different lengths. Osmotic water permeability of cells expressing KR/AQP chimeras was measured from osmotic swelling–induced dilution of cytoplasmic chloride, which was detected using a genetically encoded chloride-sensing fluorescent protein. KR-AQP1 red fluorescence was bleached rapidly (∼10% per second) by wide-field epifluorescence microscopy. After KR bleaching, KR-AQP1 water permeability was reduced by up to 80% for the chimera with the shortest linker. Remarkably, CALI-induced reduction in AQP4-KR water permeability was approximately twice as efficient for the aggregate-forming M23 isoform; this suggests intermolecular CALI, which was confirmed by native gel electrophoresis on cells coexpressing M23-AQP4-KR and myc-tagged M23-AQP4. CALI also disrupted the interaction of AQP4 with a neuromyelitis optica autoantibody directed against an extracellular epitope on AQP4. CALI thus permits rapid, spatially targeted and irreversible reduction in AQP water permeability and interactions in live cells. Our data also support the utility of CALI to study protein–protein interactions as well as other membrane transporters and receptors. The Rockefeller University Press 2012-01 /pmc/articles/PMC3250104/ /pubmed/22200949 http://dx.doi.org/10.1085/jgp.201110712 Text en © 2011 Baumgart et al. This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/).
spellingShingle Tutorial Research Article
Baumgart, Florian
Rossi, Andrea
Verkman, A.S.
Light inactivation of water transport and protein–protein interactions of aquaporin–Killer Red chimeras
title Light inactivation of water transport and protein–protein interactions of aquaporin–Killer Red chimeras
title_full Light inactivation of water transport and protein–protein interactions of aquaporin–Killer Red chimeras
title_fullStr Light inactivation of water transport and protein–protein interactions of aquaporin–Killer Red chimeras
title_full_unstemmed Light inactivation of water transport and protein–protein interactions of aquaporin–Killer Red chimeras
title_short Light inactivation of water transport and protein–protein interactions of aquaporin–Killer Red chimeras
title_sort light inactivation of water transport and protein–protein interactions of aquaporin–killer red chimeras
topic Tutorial Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3250104/
https://www.ncbi.nlm.nih.gov/pubmed/22200949
http://dx.doi.org/10.1085/jgp.201110712
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