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Lin F, Tang R, Zhang C, Scholz N, Nagel G, Gao S. Combining different ion-selective channelrhodopsins to control water flux by light. Pflugers Arch 2023; 475:1375-1385. [PMID: 37670155 PMCID: PMC10730689 DOI: 10.1007/s00424-023-02853-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 08/03/2023] [Accepted: 08/21/2023] [Indexed: 09/07/2023]
Abstract
Water transport through water channels, aquaporins (AQPs), is vital for many physiological processes including epithelial fluid secretion, cell migration and adipocyte metabolism. Water flux through AQPs is driven by the osmotic gradient that results from concentration differences of solutes including ions. Here, we developed a novel optogenetic toolkit that combines the light-gated anion channel GtACR1 either with the light-gated K+ channel HcKCR1 or the new Na+ channelrhodopsin HcNCR1 with high Na+ permeability, to manipulate water transport in Xenopus oocytes non-invasively. Water efflux through AQP was achieved by light-activating K+ and Cl- efflux through HcKCR1 and GtACR1. Contrarily, when GtACR1 was co-expressed with HcNCR1, inward movement of Na+ and Cl- was light-triggered, and the resulting osmotic gradient led to water influx through AQP1. In sum, we demonstrate a novel optogenetic strategy to manipulate water movement into or out of Xenopus oocytes non-invasively. This approach provides a new avenue to interfere with water homeostasis as a means to study related biological phenomena across cell types and organisms.
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Affiliation(s)
- Fei Lin
- Department of Neurophysiology, Institute of Physiology, Biocenter, Julius-Maximilians-University of Würzburg, Würzburg, Germany
| | - Ruijing Tang
- Department of Neurophysiology, Institute of Physiology, Biocenter, Julius-Maximilians-University of Würzburg, Würzburg, Germany
- The United Innovation of Mengchao Hepatobiliary Technology Key Laboratory of Fujian Province, Mengchao Hepatobiliary Hospital of Fujian Medical University, Fuzhou, China
| | - Chong Zhang
- Department of Neurophysiology, Institute of Physiology, Biocenter, Julius-Maximilians-University of Würzburg, Würzburg, Germany
| | - Nicole Scholz
- Rudolf Schönheimer Institute of Biochemistry, Division of General Biochemistry, Medical Faculty, Leipzig University, Johannisallee 30, 04103, Leipzig, Germany
| | - Georg Nagel
- Department of Neurophysiology, Institute of Physiology, Biocenter, Julius-Maximilians-University of Würzburg, Würzburg, Germany
| | - Shiqiang Gao
- Department of Neurophysiology, Institute of Physiology, Biocenter, Julius-Maximilians-University of Würzburg, Würzburg, Germany.
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2
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Pimpão C, Wragg D, da Silva IV, Casini A, Soveral G. Aquaglyceroporin Modulators as Emergent Pharmacological Molecules for Human Diseases. Front Mol Biosci 2022; 9:845237. [PMID: 35187089 PMCID: PMC8850838 DOI: 10.3389/fmolb.2022.845237] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2021] [Accepted: 01/13/2022] [Indexed: 12/26/2022] Open
Abstract
Aquaglyceroporins, a sub-class of aquaporins that facilitate the diffusion of water, glycerol and other small uncharged solutes across cell membranes, have been recognized for their important role in human physiology and their involvement in multiple disorders, mostly related to disturbed energy homeostasis. Aquaglyceroporins dysfunction in a variety of pathological conditions highlighted their targeting as novel therapeutic strategies, boosting the search for potent and selective modulators with pharmacological properties. The identification of selective inhibitors with potential clinical applications has been challenging, relying on accurate assays to measure membrane glycerol permeability and validate effective functional blockers. Additionally, biologicals such as hormones and natural compounds have been revealed as alternative strategies to modulate aquaglyceroporins via their gene and protein expression. This review summarizes the current knowledge of aquaglyceroporins’ involvement in several pathologies and the experimental approaches used to evaluate glycerol permeability and aquaglyceroporin modulation. In addition, we provide an update on aquaglyceroporins modulators reported to impact disease, unveiling aquaglyceroporin pharmacological targeting as a promising approach for innovative therapeutics.
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Affiliation(s)
- Catarina Pimpão
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
- Department of Pharmaceutical Sciences and Medicines, Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
| | - Darren Wragg
- Department of Chemistry, Technical University of Munich, Munich, Germany
| | - Inês V. da Silva
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
- Department of Pharmaceutical Sciences and Medicines, Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
| | - Angela Casini
- Department of Chemistry, Technical University of Munich, Munich, Germany
- *Correspondence: Angela Casini, ; Graça Soveral,
| | - Graça Soveral
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
- Department of Pharmaceutical Sciences and Medicines, Faculty of Pharmacy, Universidade de Lisboa, Lisboa, Portugal
- *Correspondence: Angela Casini, ; Graça Soveral,
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TAKEMOTO K. Optical manipulation of molecular function by chromophore-assisted light inactivation. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2021; 97:197-209. [PMID: 33840676 PMCID: PMC8062263 DOI: 10.2183/pjab.97.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Accepted: 02/09/2021] [Indexed: 06/12/2023]
Abstract
In addition to simple on/off switches for molecular activity, spatiotemporal dynamics are also thought to be important for the regulation of cellular function. However, their physiological significance and in vivo importance remain largely unknown. Fluorescence imaging technology is a powerful technique that can reveal the spatiotemporal dynamics of molecular activity. In addition, because imaging detects the correlations between molecular activity and biological phenomena, the technique of molecular manipulation is also important to analyze causal relationships. Recent advances in optical manipulation techniques that artificially perturb molecules and cells via light can address this issue to elucidate the causality between manipulated target and its physiological function. The use of light enables the manipulation of molecular activity in microspaces, such as organelles and nerve spines. In this review, we describe the chromophore-assisted light inactivation method, which is an optical manipulation technique that has been attracting attention in recent years.
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Affiliation(s)
- Kiwamu TAKEMOTO
- Department of Biochemistry, Mie University, Graduate School of Medicine, Tsu-City, Mie, Japan
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4
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Li P, Zhang L, Mo X, Ji H, Bian H, Hu Y, Majid T, Long J, Pang H, Tao Y, Ma J, Dong H. Rice aquaporin PIP1;3 and harpin Hpa1 of bacterial blight pathogen cooperate in a type III effector translocation. JOURNAL OF EXPERIMENTAL BOTANY 2019; 70:3057-3073. [PMID: 30921464 PMCID: PMC6598099 DOI: 10.1093/jxb/erz130] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 03/12/2019] [Indexed: 05/20/2023]
Abstract
Varieties of Gram-negative bacterial pathogens infect their eukaryotic hosts by deploying the type III translocon to deliver effector proteins into the cytosol of eukaryotic cells in which effectors execute their pathological functions. The translocon is hypothetically assembled by bacterial translocators in association with the assumed receptors situated on eukaryotic plasma membranes. This hypothesis is partially verified in the present study with genetic, biochemical, and pathological evidence for the role of a rice aquaporin, plasma membrane intrinsic protein PIP1;3, in the cytosolic import of the transcription activator-like effector PthXo1 from the bacterial blight pathogen. PIP1;3 interacts with the bacterial translocator Hpa1 at rice plasma membranes to control PthXo1 translocation from cells of a well-characterized strain of the bacterial blight pathogen into the cytosol of cells of a susceptible rice variety. An extracellular loop sequence of PIP1;3 and the α-helix motif of Hpa1 determine both the molecular interaction and its consequences with respect to the effector translocation and the bacterial virulence on the susceptible rice variety. Overall, these results provide multiple experimental avenues to support the hypothesis that interactions between bacterial translocators and their interactors at the target membrane are essential for bacterial effector translocation.
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Affiliation(s)
- Ping Li
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu Province, China
| | - Liyuan Zhang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu Province, China
- Department of Plant Pathology, Shandong Agricultural University, Taian, Shandong Province, China
| | - Xuyan Mo
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu Province, China
| | - Hongtao Ji
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu Province, China
- Department of Biology, Jiangsu Formal University, Xuzhou, Jiangsu Province, China
| | - Huijie Bian
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu Province, China
| | - Yiqun Hu
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu Province, China
| | - Taha Majid
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu Province, China
| | - Juying Long
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu Province, China
| | - Hao Pang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu Province, China
| | - Yuan Tao
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu Province, China
| | - Jinbiao Ma
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu Province, China
| | - Hansong Dong
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu Province, China
- Department of Plant Pathology, Shandong Agricultural University, Taian, Shandong Province, China
- Correspondence:
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Calibration and characterization of intracellular Asante Potassium Green probes, APG-2 and APG-4. Anal Biochem 2018; 567:8-13. [PMID: 30503709 DOI: 10.1016/j.ab.2018.11.024] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2018] [Revised: 11/19/2018] [Accepted: 11/28/2018] [Indexed: 12/15/2022]
Abstract
The response of fluorescent ion probes to ions is affected by intracellular environment. To properly calibrate them, intracellular and extracellular concentrations of the measured ion must be made equal. In the first, computational, part of this work, we show, using the example of potassium, that the two requirements for ion equilibration are complete dissipation of membrane potential and high membrane permeability for both potassium and sodium. In the second part, we tested the ability of various ionophores to achieve potassium equilibration in Jurkat and U937 cells and found a combination of valinomycin, nigericin, gramicidin and ouabain to be the most effective. In the third part, we applied this protocol to two potassium probes, APG-4 and APG-2. APG-4 shows good sensitivity to potassium but its fluorescence is sensitive to cell volume. Because ionophores cause cell swelling, calibration buffers had to be supplemented with 50 mM sucrose to keep cell volume constant. With these precautions taken, the average potassium concentrations in U937 and Jurkat cells were measured at 132 mM and 118 mM, respectively. The other tested probe, APG-2, is nonselective for cations; this is, however, a potentially useful property because the sum [K+] + [Na+] determines the amount of intracellular water.
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Riani YD, Matsuda T, Takemoto K, Nagai T. Green monomeric photosensitizing fluorescent protein for photo-inducible protein inactivation and cell ablation. BMC Biol 2018; 16:50. [PMID: 29712573 PMCID: PMC5928576 DOI: 10.1186/s12915-018-0514-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 04/06/2018] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND Photosensitizing fluorescent proteins, which generate reactive oxygen species (ROS) upon light irradiation, are useful for spatiotemporal protein inactivation and cell ablation. They give us clues about protein function, intracellular signaling pathways and intercellular interactions. Since ROS generation of a photosensitizer is specifically controlled by certain excitation wavelengths, utilizing colour variants of photosensitizing protein would allow multi-spatiotemporal control of inactivation. To expand the colour palette of photosensitizing protein, here we developed SuperNova Green from its red predecessor, SuperNova. RESULTS SuperNova Green is able to produce ROS spatiotemporally upon blue light irradiation. Based on protein characterization, SuperNova Green produces insignificant amounts of singlet oxygen and predominantly produces superoxide and its derivatives. We utilized SuperNova Green to specifically inactivate the pleckstrin homology domain of phospholipase C-δ1 and to ablate cancer cells in vitro. As a proof of concept for multi-spatiotemporal control of inactivation, we demonstrate that SuperNova Green can be used with its red variant, SuperNova, to perform independent protein inactivation or cell ablation studies in a spatiotemporal manner by selective light irradiation. CONCLUSION Development of SuperNova Green has expanded the photosensitizing protein toolbox to optogenetically control protein inactivation and cell ablation.
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Affiliation(s)
- Yemima Dani Riani
- Graduate School of Engineering, Osaka University, 1-3 Yamadaoka Suita, Osaka, 565-0871, Japan
| | - Tomoki Matsuda
- Graduate School of Engineering, Osaka University, 1-3 Yamadaoka Suita, Osaka, 565-0871, Japan.,The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Osaka, Ibaraki, 567-0047, Japan
| | - Kiwamu Takemoto
- Graduate School of Medicine, Yokohama City University, 22-2 Seto, Kanazawa, Yokohama, 236-0027, Japan
| | - Takeharu Nagai
- Graduate School of Engineering, Osaka University, 1-3 Yamadaoka Suita, Osaka, 565-0871, Japan. .,The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Osaka, Ibaraki, 567-0047, Japan.
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7
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Model MA, Petruccelli JC. Intracellular Macromolecules in Cell Volume Control and Methods of Their Quantification. CURRENT TOPICS IN MEMBRANES 2018; 81:237-289. [DOI: 10.1016/bs.ctm.2018.06.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Tradtrantip L, Jin BJ, Yao X, Anderson MO, Verkman AS. Aquaporin-Targeted Therapeutics: State-of-the-Field. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 969:239-250. [PMID: 28258578 DOI: 10.1007/978-94-024-1057-0_16] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Drugs targeting aquaporins have broad potential clinical applications, including cancer, obesity, edema, glaucoma, skin diseases and others. The astrocyte water channel aquaporin-4 is a particularly compelling target because of its role of brain water movement, neuroexcitation and glia scarring, and because it is the target of pathogenic autoantibodies in the neuroinflammatory demyelinating disease neuromyelitis optica . There has been considerable interest in the identification of small molecule inhibitors of aquaporins, with various candidates emerging from testing of known ion transport inhibitors, as well as compound screening and computational chemistry. However, in general, the activity of reported aquaporin inhibitors has not been confirmed on retesting, which may be due to technical problems in water transport assays used in the original identification studies, and the challenges in modulating the activity of small, compact, pore-containing membrane proteins. We review here the state of the field of aquaporin-modulating small molecules and biologics, and the challenges and opportunities in moving forward.
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Affiliation(s)
- Lukmanee Tradtrantip
- Departments of Medicine and Physiology, University of California, San Francisco, CA, 94143-0521, USA
| | - Bjung-Ju Jin
- Departments of Medicine and Physiology, University of California, San Francisco, CA, 94143-0521, USA
| | - Xiaoming Yao
- Departments of Medicine and Physiology, University of California, San Francisco, CA, 94143-0521, USA
| | - Marc O Anderson
- Department of Chemistry and Biochemistry, San Francisco State University, San Francisco, CA, 94132-4136, USA
| | - Alan S Verkman
- Departments of Medicine and Physiology, University of California, San Francisco, CA, 94143-0521, USA.
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Abstract
Volume is an essential characteristic of a cell, and this review describes the main methods of its measurement that have been used in the past several decades. The discussed methods include various implementations of light scattering, estimates based on one or two cell dimensions, surface scanning, fluorescence confocal and transmission slice-by-slice imaging, intracellular volume markers, displacement of extracellular solution, quantitative phase imaging, radioactive methods, and some others. Suitability of these methods to some typical samples and applications is discussed. © 2017 International Society for Advancement of Cytometry.
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Affiliation(s)
- Michael A Model
- Department of Biological Sciences, Kent State University, Kent, Ohio
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10
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Jin BJ, Verkman AS. Microfluidic platform for rapid measurement of transepithelial water transport. LAB ON A CHIP 2017; 17:887-895. [PMID: 28184395 PMCID: PMC5453641 DOI: 10.1039/c6lc01456a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Water transport across epithelial monolayers is of central importance in mammalian fluid homeostasis, and epithelial aquaporin (AQP) water channels are potential drug targets. Current methods to measure transepithelial water permeability based on indicator dilution have limited accuracy and can require hours for a single measurement. We report here a microfluidics platform for rapid and accurate measurement of water transport across a conventionally cultured epithelial monolayer on a porous filter requiring only a single image obtained using a standard laboratory fluorescence microscope. The undersurface of a porous polyester filter containing cultured epithelial cells on top is contacted with a perfused microfluidic channel of 100 μm width, 20 μm height and 10 cm length with folded geometry, with in-plane size of 3.2 × 3.2 mm2 for visualization with a 2× objective lens. Osmotic water permeability is measured from the steady-state concentration profile along the length of the channel of a membrane-impermeant fluorescent dye in the perfusate, in which an osmotic gradient is imposed by an anisosmolar solution overlying the epithelial monolayer; diffusional water permeability is measured using a D2O/H2O-sensing fluorescent dye in the perfusate with a D2O-containing isosmolar solution overlying the cell layer. Permeability values are deduced from single fluorescence images. The method, named fluid transport on a chip (FT-on-Chip), was applied to measure transepithelial osmotic and diffusional water permeability in control and AQP4-expressing epithelial cell monolayers. FT-on-Chip allows for rapid, accurate and repeated measurements of transepithelial water permeability, and is generalizable to transport measurements of ions and solutes using suitable indicator dyes.
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Affiliation(s)
- Byung-Ju Jin
- Departments of Medicine and Physiology, University of California, 1246 Health Sciences East Tower, San Francisco, CA 94143-0521, USA.
| | - A S Verkman
- Departments of Medicine and Physiology, University of California, 1246 Health Sciences East Tower, San Francisco, CA 94143-0521, USA.
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11
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Seno T, Ikeno T, Mennya K, Kurishita M, Sakae N, Sato M, Takada H, Konishi Y. Kinesin-1 sorting in axons controls the differential retraction of arbor terminals. J Cell Sci 2016; 129:3499-510. [PMID: 27505885 DOI: 10.1242/jcs.183806] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Accepted: 08/02/2016] [Indexed: 01/13/2023] Open
Abstract
The ability of neurons to generate multiple arbor terminals from a single axon is crucial for establishing proper neuronal wiring. Although growth and retraction of arbor terminals are differentially regulated within the axon, the mechanisms by which neurons locally control their structure remain largely unknown. In the present study, we found that the kinesin-1 (Kif5 proteins) head domain (K5H) preferentially marks a subset of arbor terminals. Time-lapse imaging clarified that these arbor terminals were more stable than others, because of a low retraction rate. Local inhibition of kinesin-1 in the arbor terminal by chromophore-assisted light inactivation (CALI) enhanced the retraction rate. The microtubule turnover was locally regulated depending on the length from the branching point to the terminal end, but did not directly correlate with the presence of K5H. By contrast, F-actin signal values in arbor terminals correlated spatiotemporally with K5H, and inhibition of actin turnover prevented retraction. Results from the present study reveal a new system mediated by kinesin-1 sorting in axons that differentially controls stability of arbor terminals.
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Affiliation(s)
- Takeshi Seno
- Department of Human and Artificial Intelligence Systems, University of Fukui, Fukui 910-8507, Japan
| | - Tatsuki Ikeno
- Department of Human and Artificial Intelligence Systems, University of Fukui, Fukui 910-8507, Japan
| | - Kousuke Mennya
- Department of Human and Artificial Intelligence Systems, University of Fukui, Fukui 910-8507, Japan
| | - Masayuki Kurishita
- Department of Human and Artificial Intelligence Systems, University of Fukui, Fukui 910-8507, Japan
| | - Narumi Sakae
- Department of Human and Artificial Intelligence Systems, University of Fukui, Fukui 910-8507, Japan
| | - Makoto Sato
- Life Science Innovation Center, University of Fukui, Fukui 910-8507, Japan Research Center for Child Mental Development, University of Fukui, Fukui 910-1193, Japan Department of Anatomy and Neuroscience, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan United Graduate School of Child Development, Osaka University, Kanazawa University-Hamamatsu University School of Medicine, Chiba University and University of Fukui, Osaka University, Osaka 565-0871, Japan
| | - Hiroki Takada
- Department of Human and Artificial Intelligence Systems, University of Fukui, Fukui 910-8507, Japan
| | - Yoshiyuki Konishi
- Department of Human and Artificial Intelligence Systems, University of Fukui, Fukui 910-8507, Japan Life Science Innovation Center, University of Fukui, Fukui 910-8507, Japan Department of Materials Science and Biotechnology, Faculty of Engineering, University of Fukui, Fukui 910-8507, Japan
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12
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Madeira A, Moura TF, Soveral G. Detecting Aquaporin Function and Regulation. Front Chem 2016; 4:3. [PMID: 26870725 PMCID: PMC4734071 DOI: 10.3389/fchem.2016.00003] [Citation(s) in RCA: 71] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 01/12/2016] [Indexed: 12/14/2022] Open
Abstract
Water is the major component of cells and tissues throughout all forms of life. Fluxes of water and solutes through cell membranes and epithelia are essential for osmoregulation and energy homeostasis. Aquaporins are membrane channels expressed in almost every organism and involved in the bidirectional transfer of water and small solutes across cell membranes. Aquaporins have important biological roles and have been implicated in several pathophysiological conditions suggesting a great translational potential in aquaporin-based diagnostics and therapeutics. Detecting aquaporin function is critical for assessing regulation and screening for new activity modulators that can prompt the development of efficient medicines. Appropriate methods for functional analysis comprising suitable cell models and techniques to accurately evaluate water and solute membrane permeability are essential to validate aquaporin function and assess short-term regulation. The present review describes established assays commonly used to assess aquaporin function in cells and tissues, as well as the experimental biophysical strategies required to reveal functional regulation and identify modulators, the first step for aquaporin drug discovery.
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Affiliation(s)
- Ana Madeira
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de Lisboa Lisboa, Portugal
| | - Teresa F Moura
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de LisboaLisboa, Portugal; Faculdade de Ciências e Tecnologia, Universidade Nova de LisboaCaparica, Portugal
| | - Graça Soveral
- Research Institute for Medicines (iMed.ULisboa), Faculty of Pharmacy, Universidade de LisboaLisboa, Portugal; Departamento Bioquimica e Biologia Humana, Faculty of Pharmacy, Universidade de LisboaLisboa, Portugal
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Beitz E, Golldack A, Rothert M, von Bülow J. Challenges and achievements in the therapeutic modulation of aquaporin functionality. Pharmacol Ther 2015; 155:22-35. [PMID: 26277280 DOI: 10.1016/j.pharmthera.2015.08.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Aquaporin (AQP) water and solute channels have basic physiological functions throughout the human body. AQP-facilitated water permeability across cell membranes is required for rapid reabsorption of water from pre-urine in the kidneys and for sustained near isosmolar water fluxes e.g. in the brain, eyes, inner ear, and lungs. Cellular water permeability is further connected to cell motility. AQPs of the aquaglyceroporin subfamily are necessary for lipid degradation in adipocytes and glycerol uptake into the liver, as well as for skin moistening. Modulation of AQP function is desirable in several pathophysiological situations, such as nephrogenic diabetes insipidus, Sjögren's syndrome, Menière's disease, heart failure, or tumors to name a few. Attempts to design or to find effective small molecule AQP inhibitors have yielded only a few hits. Challenges reside in the high copy number of AQP proteins in the cell membranes, and spatial restrictions in the protein structure. This review gives an overview on selected physiological and pathophysiological conditions in which modulation of AQP functions appears beneficial and discusses first achievements in the search of drug-like AQP inhibitors.
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Affiliation(s)
- Eric Beitz
- Pharmaceutical and Medicinal Chemistry, University of Kiel, Germany.
| | - André Golldack
- Pharmaceutical and Medicinal Chemistry, University of Kiel, Germany
| | - Monja Rothert
- Pharmaceutical and Medicinal Chemistry, University of Kiel, Germany
| | - Julia von Bülow
- Pharmaceutical and Medicinal Chemistry, University of Kiel, Germany
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Esteva-Font C, Anderson MO, Verkman AS. Urea transporter proteins as targets for small-molecule diuretics. Nat Rev Nephrol 2015; 11:113-23. [PMID: 25488859 PMCID: PMC4743986 DOI: 10.1038/nrneph.2014.219] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Conventional diuretics such as furosemide and thiazides target salt transporters in kidney tubules, but urea transporters (UTs) have emerged as alternative targets. UTs are a family of transmembrane channels expressed in a variety of mammalian tissues, in particular the kidney. UT knockout mice and humans with UT mutations exhibit reduced maximal urinary osmolality, demonstrating that UTs are necessary for the concentration of urine. Small-molecule screening has identified potent and selective inhibitors of UT-A, the UT protein expressed in renal tubule epithelial cells, and UT-B, the UT protein expressed in vasa recta endothelial cells. Data from UT knockout mice and from rodents administered UT inhibitors support the diuretic action of UT inhibition. The kidney-specific expression of UT-A1, together with high selectivity of the small-molecule inhibitors, means that off-target effects of such small-molecule drugs should be minimal. This Review summarizes the structure, expression and function of UTs, and looks at the evidence supporting the validity of UTs as targets for the development of salt-sparing diuretics with a unique mechanism of action. UT-targeted inhibitors may be useful alone or in combination with conventional diuretics for therapy of various oedemas and hyponatraemias, potentially including those refractory to treatment with current diuretics.
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Affiliation(s)
- Cristina Esteva-Font
- Departments of Medicine and Physiology, University of California, 513 Parnassus Avenue, San Francisco, CA 94143, USA
| | - Marc O Anderson
- Department of Chemistry and Biochemistry, San Francisco State University, 1600 Holloway Avenue, San Francisco, CA 94132, USA
| | - Alan S Verkman
- Departments of Medicine and Physiology, University of California, 513 Parnassus Avenue, San Francisco, CA 94143, USA
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Sano Y, Watanabe W, Matsunaga S. Chromophore-assisted laser inactivation--towards a spatiotemporal-functional analysis of proteins, and the ablation of chromatin, organelle and cell function. J Cell Sci 2014; 127:1621-9. [PMID: 24737873 DOI: 10.1242/jcs.144527] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Chromophore-assisted laser or light inactivation (CALI) has been employed as a promising technique to achieve spatiotemporal knockdown or loss-of-function of target molecules in situ. CALI is performed using photosensitizers as generators of reactive oxygen species (ROS). There are two CALI approaches that use either transgenic tags with chemical photosensitizers, or genetically encoded fluorescent protein fusions. Using spatially restricted microscopy illumination, CALI can address questions regarding, for example, protein isoforms, subcellular localization or phase-specific analyses of multifunctional proteins that other knockdown approaches, such as RNA interference or treatment with chemicals, cannot. Furthermore, rescue experiments can clarify the phenotypic capabilities of CALI after the depletion of endogenous targets. CALI can also provide information about individual events that are involved in the function of a target protein and highlight them in multifactorial events. Beyond functional analysis of proteins, CALI of nuclear proteins can be performed to induce cell cycle arrest, chromatin- or locus-specific DNA damage. Even at organelle level - such as in mitochondria, the plasma membrane or lysosomes - CALI can trigger cell death. Moreover, CALI has emerged as an optogenetic tool to switch off signaling pathways, including the optical depletion of individual neurons. In this Commentary, we review recent applications of CALI and discuss the utility and effective use of CALI to address open questions in cell biology.
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Affiliation(s)
- Yukimi Sano
- Department of Applied Biological Science, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
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Abstract
The aquaporins (AQPs) are a family of small, integral membrane proteins that facilitate water transport across the plasma membranes of cells in response to osmotic gradients. Data from knockout mice support the involvement of AQPs in epithelial fluid secretion, cell migration, brain oedema and adipocyte metabolism, which suggests that modulation of AQP function or expression could have therapeutic potential in oedema, cancer, obesity, brain injury, glaucoma and several other conditions. Moreover, loss-of-function mutations in human AQPs cause congenital cataracts (AQP0) and nephrogenic diabetes insipidus (AQP2), and autoantibodies against AQP4 cause the autoimmune demyelinating disease neuromyelitis optica. Although some potential AQP modulators have been identified, challenges associated with the development of better modulators include the druggability of the target and the suitability of the assay methods used to identify modulators.
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Schmitt FJ, Renger G, Friedrich T, Kreslavski VD, Zharmukhamedov SK, Los DA, Kuznetsov VV, Allakhverdiev SI. Reactive oxygen species: re-evaluation of generation, monitoring and role in stress-signaling in phototrophic organisms. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2014; 1837:835-48. [PMID: 24530357 DOI: 10.1016/j.bbabio.2014.02.005] [Citation(s) in RCA: 154] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 02/06/2014] [Accepted: 02/07/2014] [Indexed: 12/11/2022]
Abstract
This review provides an overview about recent developments and current knowledge about monitoring, generation and the functional role of reactive oxygen species (ROS) - H2O2, HO2, HO, OH(-), (1)O2 and O2(-) - in both oxidative degradation and signal transduction in photosynthetic organisms including microscopic techniques for ROS detection and controlled generation. Reaction schemes elucidating formation, decay and signaling of ROS in cyanobacteria as well as from chloroplasts to the nuclear genome in eukaryotes during exposure of oxygen-evolving photosynthetic organisms to oxidative stress are discussed that target the rapidly growing field of regulatory effects of ROS on nuclear gene expression.
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Affiliation(s)
- Franz-Josef Schmitt
- Technical University Berlin, Institute of Chemistry, Sekr. PC 14, Max-Volmer-Laboratory of Biophysical Chemistry, Straße des 17. Juni 135, D-10623 Berlin, Germany
| | - Gernot Renger
- Technical University Berlin, Institute of Chemistry, Sekr. PC 14, Max-Volmer-Laboratory of Biophysical Chemistry, Straße des 17. Juni 135, D-10623 Berlin, Germany
| | - Thomas Friedrich
- Technical University Berlin, Institute of Chemistry, Sekr. PC 14, Max-Volmer-Laboratory of Biophysical Chemistry, Straße des 17. Juni 135, D-10623 Berlin, Germany
| | - Vladimir D Kreslavski
- Institute of Basic Biological Problems, Russian Academy of Sciences, Institutskaya Street 2, Pushchino, Moscow Region 142290, Russia; Institute of Plant Physiology, Russian Academy of Sciences, Botanicheskaya Street 35, Moscow 127276, Russia
| | - Sergei K Zharmukhamedov
- Institute of Basic Biological Problems, Russian Academy of Sciences, Institutskaya Street 2, Pushchino, Moscow Region 142290, Russia
| | - Dmitry A Los
- Institute of Plant Physiology, Russian Academy of Sciences, Botanicheskaya Street 35, Moscow 127276, Russia
| | - Vladimir V Kuznetsov
- Institute of Plant Physiology, Russian Academy of Sciences, Botanicheskaya Street 35, Moscow 127276, Russia; Tomsk State University, Lenin Avenue 36, Tomsk 634050, Russia
| | - Suleyman I Allakhverdiev
- Institute of Basic Biological Problems, Russian Academy of Sciences, Institutskaya Street 2, Pushchino, Moscow Region 142290, Russia; Institute of Plant Physiology, Russian Academy of Sciences, Botanicheskaya Street 35, Moscow 127276, Russia.
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Sack JT, Stephanopoulos N, Austin DC, Francis MB, Trimmer JS. Antibody-guided photoablation of voltage-gated potassium currents. ACTA ACUST UNITED AC 2013; 142:315-24. [PMID: 23940262 PMCID: PMC3753605 DOI: 10.1085/jgp.201311023] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
A family of 40 mammalian voltage-gated potassium (Kv) channels control membrane excitability in electrically excitable cells. The contribution of individual Kv channel types to electrophysiological signaling has been difficult to assign, as few selective inhibitors exist for individual Kv subunits. Guided by the exquisite selectivity of immune system interactions, we find potential for antibody conjugates as selective Kv inhibitors. Here, functionally benign anti-Kv channel monoclonal antibodies (mAbs) were chemically modified to facilitate photoablation of K currents. Antibodies were conjugated to porphyrin compounds that upon photostimulation inflict localized oxidative damage. Anti-Kv4.2 mAb–porphyrin conjugates facilitated photoablation of Kv4.2 currents. The degree of K current ablation was dependent on photon dose and conjugate concentration. Kv channel photoablation was selective for Kv4.2 over Kv4.3 or Kv2.1, yielding specificity not present in existing neurotoxins or other Kv channel inhibitors. We conclude that antibody–porphyrin conjugates are capable of selective photoablation of Kv currents. These findings demonstrate that subtype-specific mAbs that in themselves do not modulate ion channel function are capable of delivering functional payloads to specific ion channel targets.
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Affiliation(s)
- Jon T Sack
- Department of Physiology and Membrane Biology, University of California, Davis, Davis, CA 95616, USA.
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