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Bayraktar E, Lopez-Pigozzi D, Bortolozzi M. Calcium Regulation of Connexin Hemichannels. Int J Mol Sci 2024; 25:6594. [PMID: 38928300 PMCID: PMC11204158 DOI: 10.3390/ijms25126594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2024] [Revised: 06/07/2024] [Accepted: 06/12/2024] [Indexed: 06/28/2024] Open
Abstract
Connexin hemichannels (HCs) expressed at the plasma membrane of mammalian cells are of paramount importance for intercellular communication. In physiological conditions, HCs can form gap junction (GJ) channels, providing a direct diffusive path between neighbouring cells. In addition, unpaired HCs provide conduits for the exchange of solutes between the cytoplasm and the extracellular milieu, including messenger molecules involved in paracrine signalling. The synergistic action of membrane potential and Ca2+ ions controls the gating of the large and relatively unselective pore of connexin HCs. The four orders of magnitude difference in gating sensitivity to the extracellular ([Ca2+]e) and the cytosolic ([Ca2+]c) Ca2+ concentrations suggests that at least two different Ca2+ sensors may exist. While [Ca2+]e acts as a spatial modulator of the HC opening, which is most likely dependent on the cell layer, compartment, and organ, [Ca2+]c triggers HC opening and the release of extracellular bursts of messenger molecules. Such molecules include ATP, cAMP, glutamate, NAD+, glutathione, D-serine, and prostaglandins. Lost or abnormal HC regulation by Ca2+ has been associated with several diseases, including deafness, keratitis ichthyosis, palmoplantar keratoderma, Charcot-Marie-Tooth neuropathy, oculodentodigital dysplasia, and congenital cataracts. The fact that both an increased and a decreased Ca2+ sensitivity has been linked to pathological conditions suggests that Ca2+ in healthy cells finely tunes the normal HC function. Overall, further investigation is needed to clarify the structural and chemical modifications of connexin HCs during [Ca2+]e and [Ca2+]c variations. A molecular model that accounts for changes in both Ca2+ and the transmembrane voltage will undoubtedly enhance our interpretation of the experimental results and pave the way for developing therapeutic compounds targeting specific HC dysfunctions.
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Affiliation(s)
- Erva Bayraktar
- Veneto Institute of Molecular Medicine (VIMM), Via Orus 2, 35129 Padova, Italy
- Department of Physics and Astronomy “G. Galilei”, University of Padua, Via Marzolo 8, 35131 Padova, Italy
| | - Diego Lopez-Pigozzi
- Veneto Institute of Molecular Medicine (VIMM), Via Orus 2, 35129 Padova, Italy
- Department of Physics and Astronomy “G. Galilei”, University of Padua, Via Marzolo 8, 35131 Padova, Italy
| | - Mario Bortolozzi
- Veneto Institute of Molecular Medicine (VIMM), Via Orus 2, 35129 Padova, Italy
- Department of Physics and Astronomy “G. Galilei”, University of Padua, Via Marzolo 8, 35131 Padova, Italy
- Institute of Endocrinology and Oncology “Gaetano Salvatore” (IEOS-CNR), Via Pietro Castellino 111, 80131 Napoli, Italy
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2
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van Megen WH, Canki E, Wagenaar VHA, van Waes CRMM, Peters DJM, Van Asbeck-Van der Wijst J, Hoenderop JGJ. Fluid shear stress stimulates ATP release without regulating purinergic gene expression in the renal inner medullary collecting duct. FASEB J 2023; 37:e23232. [PMID: 37819258 DOI: 10.1096/fj.202301434r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 09/14/2023] [Accepted: 09/19/2023] [Indexed: 10/13/2023]
Abstract
In the kidney, the flow rate of the pro-urine through the renal tubules is highly variable. The tubular epithelial cells sense these variations in pro-urinary flow rate in order to regulate various physiological processes, including electrolyte reabsorption. One of the mechanosensitive pathways activated by flow is the release of ATP, which can then act as a autocrine or paracrine factor. Increased ATP release is observed in various kidney diseases, among others autosomal dominant polycystic kidney disease (ADPKD). However, the mechanisms underlying flow-induced ATP release in the collecting duct, especially in the inner medullary collecting duct, remain understudied. Using inner medullary collecting duct 3 (IMCD3) cells in a microfluidic setup, we show here that administration of a high flow rate for 1 min results in an increased ATP release compared to a lower flow rate. Although the ATP release channel pannexin-1 contributed to flow-induced ATP release in Pkd1-/- IMCD3 cells, it did not in wildtype IMCD3 cells. In addition, flow application increased the expression of the putative ATP release channel connexin-30.3 (CX30.3) in wildtype and Pkd1-/- IMCD3 cells. However, CX30.3 knockout IMCD3 cells exhibited a similar flow-induced ATP release as wildtype IMCD3 cells, suggesting that CX30.3 does not drive flow-induced ATP release in wildtype IMDC3 cells. Collectively, our results show differential mechanisms underlying flow-induced ATP release in wildtype and Pkd1-/- IMCD3 cells and further strengthen the link between ADPKD and pannexin-1-dependent ATP release.
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Affiliation(s)
- Wouter H van Megen
- Department of Medical Biosciences, Radboudumc, Nijmegen, The Netherlands
| | - Esra Canki
- Department of Medical Biosciences, Radboudumc, Nijmegen, The Netherlands
| | - Vera H A Wagenaar
- Department of Medical Biosciences, Radboudumc, Nijmegen, The Netherlands
| | | | - Dorien J M Peters
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
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3
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Garfa Traoré M, Roccio F, Miceli C, Ferri G, Parisot M, Cagnard N, Lhomme M, Dupont N, Benmerah A, Saunier S, Delous M. Fluid shear stress triggers cholesterol biosynthesis and uptake in inner medullary collecting duct cells, independently of nephrocystin-1 and nephrocystin-4. Front Mol Biosci 2023; 10:1254691. [PMID: 37916190 PMCID: PMC10616263 DOI: 10.3389/fmolb.2023.1254691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2023] [Accepted: 09/15/2023] [Indexed: 11/03/2023] Open
Abstract
Renal epithelial cells are subjected to fluid shear stress of urine flow. Several cellular structures act as mechanosensors-the primary cilium, microvilli and cell adhesion complexes-that directly relay signals to the cytoskeleton to regulate various processes including cell differentiation and renal cell functions. Nephronophthisis (NPH) is an autosomal recessive tubulointerstitial nephropathy leading to end-stage kidney failure before adulthood. NPHP1 and NPHP4 are the major genes which code for proteins that form a complex at the transition zone of the primary cilium, a crucial region required for the maintenance of the ciliary composition integrity. These two proteins also interact with signaling components and proteins associated with the actin cytoskeleton at cell junctions. Due to their specific subcellular localization, we wondered whether NPHP1 and NPHP4 could ensure mechanosensory functions. Using a microfluidic set up, we showed that murine inner medullary collecting ductal cells invalidated for Nphp1 or Nphp4 are more responsive to immediate shear exposure with a fast calcium influx, and upon a prolonged shear condition, an inability to properly regulate cilium length and actin cytoskeleton remodeling. Following a transcriptomic study highlighting shear stress-induced gene expression changes, we showed that prolonged shear triggers both cholesterol biosynthesis pathway and uptake, processes that do not seem to involve neither NPHP1 nor NPHP4. To conclude, our study allowed us to determine a moderate role of NPHP1 and NPHP4 in flow sensation, and to highlight a new signaling pathway induced by shear stress, the cholesterol biosynthesis and uptake pathways, which would allow cells to cope with mechanical stress by strengthening their plasma membrane through the supply of cholesterol.
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Affiliation(s)
- Meriem Garfa Traoré
- Laboratory of Hereditary Kidney Disease, INSERM UMR 1163, Imagine Institute, Université Paris Cité, Paris, France
- Cell Imaging Platform, Structure Fédérative de Recherche Necker, INSERM US24/CNRS UMS3633, Université Paris Cité, Paris, France
| | - Federica Roccio
- Institut Necker Enfants-Malades (INEM), INSERM U1151/CNRS UMR 8253, Université Paris Cité, Paris, France
| | - Caterina Miceli
- Institut Necker Enfants-Malades (INEM), INSERM U1151/CNRS UMR 8253, Université Paris Cité, Paris, France
| | - Giulia Ferri
- Laboratory of Hereditary Kidney Disease, INSERM UMR 1163, Imagine Institute, Université Paris Cité, Paris, France
| | - Mélanie Parisot
- Genomics Core Facility, Institut Imagine-Structure Fédérative de Recherche Necker, INSERM U1163 et INSERM US24/CNRS UMS3633, Université Paris Cité, Paris, France
| | - Nicolas Cagnard
- Bioinformatic Platform, Institut Imagine-Structure Fédérative de Recherche Necker, INSERM U1163 et INSERM US24/CNRS UMS3633, Université Paris Cité, Paris, France
| | - Marie Lhomme
- ICAN Omics, IHU ICAN Foundation for Innovation in Cardiometabolism and Nutrition, Pitié-Salpêtrière Hospital, Paris, France
| | - Nicolas Dupont
- Institut Necker Enfants-Malades (INEM), INSERM U1151/CNRS UMR 8253, Université Paris Cité, Paris, France
| | - Alexandre Benmerah
- Laboratory of Hereditary Kidney Disease, INSERM UMR 1163, Imagine Institute, Université Paris Cité, Paris, France
| | - Sophie Saunier
- Laboratory of Hereditary Kidney Disease, INSERM UMR 1163, Imagine Institute, Université Paris Cité, Paris, France
| | - Marion Delous
- Laboratory of Hereditary Kidney Disease, INSERM UMR 1163, Imagine Institute, Université Paris Cité, Paris, France
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4
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Hypertensive Nephropathy: Unveiling the Possible Involvement of Hemichannels and Pannexons. Int J Mol Sci 2022; 23:ijms232415936. [PMID: 36555574 PMCID: PMC9785367 DOI: 10.3390/ijms232415936] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 12/09/2022] [Accepted: 12/12/2022] [Indexed: 12/23/2022] Open
Abstract
Hypertension is one of the most common risk factors for developing chronic cardiovascular diseases, including hypertensive nephropathy. Within the glomerulus, hypertension causes damage and activation of mesangial cells (MCs), eliciting the production of large amounts of vasoactive and proinflammatory agents. Accordingly, the activation of AT1 receptors by the vasoactive molecule angiotensin II (AngII) contributes to the pathogenesis of renal damage, which is mediated mostly by the dysfunction of intracellular Ca2+ ([Ca2+]i) signaling. Similarly, inflammation entails complex processes, where [Ca2+]i also play crucial roles. Deregulation of this second messenger increases cell damage and promotes fibrosis, reduces renal blood flow, and impairs the glomerular filtration barrier. In vertebrates, [Ca2+]i signaling depends, in part, on the activity of two families of large-pore channels: hemichannels and pannexons. Interestingly, the opening of these channels depends on [Ca2+]i signaling. In this review, we propose that the opening of channels formed by connexins and/or pannexins mediated by AngII induces the ATP release to the extracellular media, with the subsequent activation of purinergic receptors. This process could elicit Ca2+ overload and constitute a feed-forward mechanism, leading to kidney damage.
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Shutova MS, Boehncke WH. Mechanotransduction in Skin Inflammation. Cells 2022; 11:cells11132026. [PMID: 35805110 PMCID: PMC9265324 DOI: 10.3390/cells11132026] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 06/20/2022] [Accepted: 06/22/2022] [Indexed: 11/16/2022] Open
Abstract
In the process of mechanotransduction, the cells in the body perceive and interpret mechanical stimuli to maintain tissue homeostasis and respond to the environmental changes. Increasing evidence points towards dysregulated mechanotransduction as a pathologically relevant factor in human diseases, including inflammatory conditions. Skin is the organ that constantly undergoes considerable mechanical stresses, and the ability of mechanical factors to provoke inflammatory processes in the skin has long been known, with the Koebner phenomenon being an example. However, the molecular mechanisms and key factors linking mechanotransduction and cutaneous inflammation remain understudied. In this review, we outline the key players in the tissue’s mechanical homeostasis, the available data, and the gaps in our current understanding of their aberrant regulation in chronic cutaneous inflammation. We mainly focus on psoriasis as one of the most studied skin inflammatory diseases; we also discuss mechanotransduction in the context of skin fibrosis as a result of chronic inflammation. Even though the role of mechanotransduction in inflammation of the simple epithelia of internal organs is being actively studied, we conclude that the mechanoregulation in the stratified epidermis of the skin requires more attention in future translational research.
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Affiliation(s)
- Maria S. Shutova
- Department of Pathology and Immunology, University of Geneva, 1211 Geneva, Switzerland;
- Department of Dermatology, Geneva University Hospitals, 1211 Geneva, Switzerland
- Correspondence:
| | - Wolf-Henning Boehncke
- Department of Pathology and Immunology, University of Geneva, 1211 Geneva, Switzerland;
- Department of Dermatology, Geneva University Hospitals, 1211 Geneva, Switzerland
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6
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Peng B, Xu C, Wang S, Zhang Y, Li W. The Role of Connexin Hemichannels in Inflammatory Diseases. BIOLOGY 2022; 11:biology11020237. [PMID: 35205103 PMCID: PMC8869213 DOI: 10.3390/biology11020237] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 01/28/2022] [Accepted: 02/01/2022] [Indexed: 02/04/2023]
Abstract
The connexin protein family consists of approximately 20 members, and is well recognized as the structural unit of the gap junction channels that perforate the plasma membranes of coupled cells and, thereby, mediate intercellular communication. Gap junctions are assembled by two preexisting hemichannels on the membranes of apposing cells. Non-junctional connexin hemichannels (CxHC) provide a conduit between the cell interior and the extracellular milieu, and are believed to be in a protectively closed state under physiological conditions. The development and characterization of the peptide mimetics of the amino acid sequences of connexins have resulted in the development of a panel of blockers with a higher selectivity for CxHC, which have become important tools for defining the role of CxHC in various biological processes. It is increasingly clear that CxHC can be induced to open by pathogen-associated molecular patterns. The opening of CxHC facilitates the release of damage-associated molecular patterns, a class of endogenous molecules that are critical for the pathogenesis of inflammatory diseases. The blockade of CxHC leads to attenuated inflammation, reduced tissue injury and improved organ function in human and animal models of about thirty inflammatory diseases and disorders. These findings demonstrate that CxHC may contribute to the intensification of inflammation, and serve as a common target in the treatments of various inflammatory diseases. In this review, we provide an update on the progress in the understanding of CxHC, with a focus on the role of these channels in inflammatory diseases.
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Affiliation(s)
| | | | | | - Yijie Zhang
- Correspondence: (Y.Z.); (W.L.); Tel.: +86-13903782431 (Y.Z.); +86-17839250252 (W.L.)
| | - Wei Li
- Correspondence: (Y.Z.); (W.L.); Tel.: +86-13903782431 (Y.Z.); +86-17839250252 (W.L.)
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7
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Olesen ETB, Fenton RA. Aquaporin 2 regulation: implications for water balance and polycystic kidney diseases. Nat Rev Nephrol 2021; 17:765-781. [PMID: 34211154 DOI: 10.1038/s41581-021-00447-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/21/2021] [Indexed: 02/06/2023]
Abstract
Targeting the collecting duct water channel aquaporin 2 (AQP2) to the plasma membrane is essential for the maintenance of mammalian water homeostasis. The vasopressin V2 receptor (V2R), which is a GS protein-coupled receptor that increases intracellular cAMP levels, has a major role in this targeting process. Although a rise in cAMP levels and activation of protein kinase A are involved in facilitating the actions of V2R, studies in knockout mice and cell models have suggested that cAMP signalling pathways are not an absolute requirement for V2R-mediated AQP2 trafficking to the plasma membrane. In addition, although AQP2 phosphorylation is a known prerequisite for V2R-mediated plasma membrane targeting, none of the known AQP2 phosphorylation events appears to be rate-limiting in this process, which suggests the involvement of other factors; cytoskeletal remodelling has also been implicated. Notably, several regulatory processes and signalling pathways involved in AQP2 trafficking also have a role in the pathophysiology of autosomal dominant polycystic kidney disease, although the role of AQP2 in cyst progression is unknown. Here, we highlight advances in the field of AQP2 regulation that might be exploited for the treatment of water balance disorders and provide a rationale for targeting these pathways in autosomal dominant polycystic kidney disease.
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Affiliation(s)
- Emma T B Olesen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark. .,Department of Endocrinology and Nephrology, North Zealand Hospital, Hillerød, Denmark.
| | - Robert A Fenton
- Department of Biomedicine, Faculty of Health, Aarhus University, Aarhus, Denmark.
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8
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Barros Lamus ER, Carotti V, de Vries CRS, Witsel F, Arntz OJ, van de Loo FAJ, Carvajal CA, Bindels RJM, Hoenderop JGJ, Rigalli JP. Extracellular vesicles regulate purinergic signaling and epithelial sodium channel expression in renal collecting duct cells. FASEB J 2021; 35:e21506. [PMID: 33811695 DOI: 10.1096/fj.202002559r] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 02/04/2021] [Accepted: 02/22/2021] [Indexed: 12/12/2022]
Abstract
Purinergic signaling regulates several renal physiological and pathophysiological processes. Extracellular vesicles (EVs) are nanoparticles released by most cell types, which, in non-renal tissues, modulate purinergic signaling. The aim of this study was to investigate the effect of EVs from renal proximal tubule (HK2) and collecting duct cells (HCD) on intra- and intersegment modulation of extracellular ATP levels, the underlying molecular mechanisms, and the impact on the expression of the alpha subunit of the epithelial sodium channel (αENaC). HK2 cells were exposed to HK2 EVs, while HCD cells were exposed to HK2 and HCD EVs. Extracellular ATP levels and αENaC expression were measured by chemiluminescence and qRT-PCR, respectively. ATPases in EV populations were identified by mass spectrometry. The effect of aldosterone was assessed using EVs from aldosterone-treated cells and urinary EVs (uEVs) from primary aldosteronism (PA) patients. HK2 EVs downregulated ectonucleoside-triphosphate-diphosphohydrolase-1 (ENTPD1) expression, increased extracellular ATP and downregulated αENaC expression in HCD cells. ENTPD1 downregulation could be attributed to increased miR-205-3p and miR-505 levels. Conversely, HCD EVs decreased extracellular ATP levels and upregulated αENaC expression in HCD cells, probably due to enrichment of 14-3-3 isoforms with ATPase activity. Pretreatment of donor cells with aldosterone or exposure to uEVs from PA patients enhanced the effects on extracellular ATP and αENaC expression. We demonstrated inter- and intrasegment modulation of renal purinergic signaling by EVs. Our findings postulate EVs as carriers of information along the renal tubules, whereby processes affecting EV release and/or cargo may impact on purinergically regulated processes.
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Affiliation(s)
- Eric R Barros Lamus
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands.,Department of Endocrinology, School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Valentina Carotti
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Christine R S de Vries
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Femke Witsel
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Onno J Arntz
- Department of Rheumatology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Fons A J van de Loo
- Department of Rheumatology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Cristian A Carvajal
- Department of Endocrinology, School of Medicine, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - René J M Bindels
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Joost G J Hoenderop
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Juan P Rigalli
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
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9
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Kong Q, Quan Y, Tian G, Zhou J, Liu X. Purinergic P2 Receptors: Novel Mediators of Mechanotransduction. Front Pharmacol 2021; 12:671809. [PMID: 34025431 PMCID: PMC8138185 DOI: 10.3389/fphar.2021.671809] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 04/26/2021] [Indexed: 02/05/2023] Open
Abstract
Mechanosensing and mechanotransduction are vital processes in mechanobiology and play critical roles in regulating cellular behavior and fate. There is increasing evidence that purinergic P2 receptors, members of the purinergic family, play a crucial role in cellular mechanotransduction. Thus, information on the specific mechanism of P2 receptor-mediated mechanotransduction would be valuable. In this review, we focus on purinergic P2 receptor signaling pathways and describe in detail the interaction of P2 receptors with other mechanosensitive molecules, including transient receptor potential channels, integrins, caveolae-associated proteins and hemichannels. In addition, we review the activation of purinergic P2 receptors and the role of various P2 receptors in the regulation of various pathophysiological processes induced by mechanical stimuli.
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Affiliation(s)
- Qihang Kong
- Laboratory of Cardiovascular Diseases, Regenerative Medicine Research Center, West China Hospital, Sichuan University, Chengdu, China
| | - Yue Quan
- Laboratory of Cardiovascular Diseases, Regenerative Medicine Research Center, West China Hospital, Sichuan University, Chengdu, China
| | - Geer Tian
- Laboratory of Cardiovascular Diseases, Regenerative Medicine Research Center, West China Hospital, Sichuan University, Chengdu, China
| | - Junteng Zhou
- Department of Cardiology, West China Hospital, Sichuan University, Chengdu, China
| | - Xiaojing Liu
- Laboratory of Cardiovascular Diseases, Regenerative Medicine Research Center, West China Hospital, Sichuan University, Chengdu, China.,Department of Cardiology, West China Hospital, Sichuan University, Chengdu, China
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10
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Ilyaskin AV, Korbmacher C, Diakov A. Inhibition of the epithelial sodium channel (ENaC) by connexin 30 involves stimulation of clathrin-mediated endocytosis. J Biol Chem 2021; 296:100404. [PMID: 33577799 PMCID: PMC7973139 DOI: 10.1016/j.jbc.2021.100404] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 02/05/2021] [Accepted: 02/08/2021] [Indexed: 01/16/2023] Open
Abstract
Mice lacking connexin 30 (Cx30) display increased epithelial sodium channel (ENaC) activity in the distal nephron and develop salt-sensitive hypertension. This indicates a functional link between Cx30 and ENaC, which remains incompletely understood. Here, we explore the effect of Cx30 on ENaC function using the Xenopus laevis oocyte expression system. Coexpression of human Cx30 with human αβγENaC significantly reduced ENaC-mediated whole-cell currents. The size of the inhibitory effect on ENaC depended on the expression level of Cx30 and required Cx30 ion channel activity. ENaC inhibition by Cx30 was mainly due to reduced cell surface ENaC expression resulting from enhanced ENaC retrieval without discernible effects on proteolytic channel activation and single-channel properties. ENaC retrieval from the cell surface involves the interaction of the ubiquitin ligase Nedd4-2 with PPPxY-motifs in the C-termini of ENaC. Truncating the C- termini of β- or γENaC significantly reduced the inhibitory effect of Cx30 on ENaC. In contrast, mutating the prolines belonging to the PPPxY-motif in γENaC or coexpressing a dominant-negative Xenopus Nedd4 (xNedd4-CS) did not significantly alter ENaC inhibition by Cx30. Importantly, the inhibitory effect of Cx30 on ENaC was significantly reduced by Pitstop-2, an inhibitor of clathrin-mediated endocytosis, or by mutating putative clathrin adaptor protein 2 (AP-2) recognition motifs (YxxФ) in the C termini of β- or γ-ENaC. In conclusion, our findings suggest that Cx30 inhibits ENaC by promoting channel retrieval from the plasma membrane via clathrin-dependent endocytosis. Lack of this inhibition may contribute to increased ENaC activity and salt-sensitive hypertension in mice with Cx30 deficiency.
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Affiliation(s)
- Alexandr V Ilyaskin
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Christoph Korbmacher
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany.
| | - Alexei Diakov
- Institut für Zelluläre und Molekulare Physiologie, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
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11
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Martins JR, Haenni D, Bugarski M, Figurek A, Hall AM. Quantitative intravital Ca2+ imaging maps single cell behavior to kidney tubular structure. Am J Physiol Renal Physiol 2020; 319:F245-F255. [DOI: 10.1152/ajprenal.00052.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Ca2+ is an important second messenger that translates extracellular stimuli into intracellular responses. Although there has been significant progress in understanding Ca2+ dynamics in organs such as the brain, the nature of Ca2+ signals in the kidney is still poorly understood. Here, we show that by using a genetically expressed highly sensitive reporter (GCaMP6s), it is possible to perform imaging of Ca2+ signals at high resolution in the mouse kidney in vivo. Moreover, by applying machine learning-based automated analysis using a Ca2+-independent signal, quantitative data can be extracted in an unbiased manner. By projecting the resulting data onto the structure of the kidney, we show that different tubular segments display highly distinct spatiotemporal patterns of Ca2+ signals. Furthermore, we provide evidence that Ca2+ activity in the proximal tubule decreases with increasing distance from the glomerulus. Finally, we demonstrate that substantial changes in intracellular Ca2+ can be detected in proximal tubules in a cisplatin model of acute kidney injury, which can be linked to alterations in cell structure and transport function. In summary, we describe a powerful new tool to investigate how single cell behavior is integrated with whole organ structure and function and how it is altered in disease states relevant to humans.
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Affiliation(s)
| | - Dominik Haenni
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
- Center for Microscopy and Image Analysis, University of Zurich, Zurich, Switzerland
| | - Milica Bugarski
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
| | - Andreja Figurek
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
| | - Andrew M. Hall
- Institute of Anatomy, University of Zurich, Zurich, Switzerland
- Department of Nephrology, University Hospital Zurich, Zurich, Switzerland
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12
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Ghézali G, Vasile F, Curry N, Fantham M, Cheung G, Ezan P, Cohen-Salmon M, Kaminski C, Rouach N. Neuronal Activity Drives Astroglial Connexin 30 in Perisynaptic Processes and Shapes Its Functions. Cereb Cortex 2020; 30:753-766. [PMID: 31271200 PMCID: PMC7086174 DOI: 10.1093/cercor/bhz123] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2018] [Revised: 04/22/2019] [Accepted: 05/17/2019] [Indexed: 12/17/2022] Open
Abstract
Astrocytes play key roles in brain functions through dynamic interactions with neurons. One of their typical features is to express high levels of connexins (Cxs), Cx43 and Cx30, the gap junction (GJ)-forming proteins. Cx30 is involved in basic cognitive processes and shapes synaptic and network activities, as shown by recent studies in transgenic animals. Yet it remains unknown whether astroglial Cx30 expression, localization, and functions are endogenously and dynamically regulated by neuronal activity and could therefore play physiological roles in neurotransmission. We here show that neuronal activity increased hippocampal Cx30 protein levels via a posttranslational mechanism regulating lysosomal degradation. Neuronal activity also increased Cx30 protein levels at membranes and perisynaptic processes, as revealed by superresolution imaging. This translated at the functional level in the activation of Cx30 hemichannels and in Cx30-mediated remodeling of astrocyte morphology independently of GJ biochemical coupling. Altogether, these data show activity-dependent dynamics of Cx30 expression, perisynaptic localization, and functions.
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Affiliation(s)
- Grégory Ghézali
- Neuroglial Interactions in Cerebral Physiology, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, 75005 Paris, France
- Doctoral School N° 158, Pierre and Marie Curie University, 75006 Paris, France
| | - Flora Vasile
- Neuroglial Interactions in Cerebral Physiology, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, 75005 Paris, France
- Doctoral School N°474, Rene Descartes University, 75006 Paris, France
| | - Nathan Curry
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| | - Marcus Fantham
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| | - Giselle Cheung
- Neuroglial Interactions in Cerebral Physiology, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, 75005 Paris, France
| | - Pascal Ezan
- Neuroglial Interactions in Cerebral Physiology, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, 75005 Paris, France
| | - Martine Cohen-Salmon
- Neuroglial Interactions in Cerebral Physiology, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, 75005 Paris, France
| | - Clemens Kaminski
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Cambridge CB3 0AS, UK
| | - Nathalie Rouach
- Neuroglial Interactions in Cerebral Physiology, Center for Interdisciplinary Research in Biology, Collège de France, CNRS UMR 7241, INSERM U1050, Labex Memolife, PSL Research University, 75005 Paris, France
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13
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Verschuren EHJ, Rigalli JP, Castenmiller C, Rohrbach MU, Bindels RJM, Peters DJM, Arjona FJ, Hoenderop JGJ. Pannexin-1 mediates fluid shear stress-sensitive purinergic signaling and cyst growth in polycystic kidney disease. FASEB J 2020; 34:6382-6398. [PMID: 32159259 DOI: 10.1096/fj.201902901r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 02/07/2020] [Accepted: 03/01/2020] [Indexed: 12/16/2022]
Abstract
Tubular ATP release is regulated by mechanosensation of fluid shear stress (FSS). Polycystin-1/polycystin-2 (PC1/PC2) functions as a mechanosensory complex in the kidney. Extracellular ATP is implicated in polycystic kidney disease (PKD), where PC1/PC2 is dysfunctional. This study aims to provide new insights into the ATP signaling under physiological conditions and PKD. Microfluidics, pharmacologic inhibition, and loss-of-function approaches were combined to assess the ATP release in mouse distal convoluted tubule 15 (mDCT15) cells. Kidney-specific Pkd1 knockout mice (iKsp-Pkd1-/- ) and zebrafish pkd2 morphants (pkd2-MO) were as models for PKD. FSS-exposed mDCT15 cells displayed increased ATP release. Pannexin-1 inhibition and knockout decreased FSS-modulated ATP release. In iKsp-Pkd1-/- mice, elevated renal pannexin-1 mRNA expression and urinary ATP were observed. In Pkd1-/- mDCT15 cells, elevated ATP release was observed upon the FSS mechanosensation. In these cells, increased pannexin-1 mRNA expression was observed. Importantly, pannexin-1 inhibition in pkd2-MO decreased the renal cyst growth. Our results demonstrate that pannexin-1 channels mediate ATP release into the tubular lumen due to pro-urinary flow. We present pannexin-1 as novel therapeutic target to prevent the renal cyst growth in PKD.
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Affiliation(s)
- Eric H J Verschuren
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Juan P Rigalli
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Charlotte Castenmiller
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Meike U Rohrbach
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - René J M Bindels
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Dorien J M Peters
- Department of Human Genetics, Leiden University Medical Center, Leiden, the Netherlands
| | - Francisco J Arjona
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
| | - Joost G J Hoenderop
- Department of Physiology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, the Netherlands
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14
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Verschuren EHJ, Castenmiller C, Peters DJM, Arjona FJ, Bindels RJM, Hoenderop JGJ. Sensing of tubular flow and renal electrolyte transport. Nat Rev Nephrol 2020; 16:337-351. [DOI: 10.1038/s41581-020-0259-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/06/2020] [Indexed: 02/06/2023]
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15
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Sarrouilhe D, Mesnil M, Dejean C. Targeting Gap Junctions: New Insights into the Treatment of Major Depressive Disorder. Curr Med Chem 2019; 26:3775-3791. [DOI: 10.2174/0929867325666180327103530] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Revised: 12/22/2017] [Accepted: 03/21/2018] [Indexed: 01/05/2023]
Abstract
Background:Major depressive disorder (MDD) is a multifactorial chronic and debilitating mood disease with high lifetime prevalence and associated with excess mortality. Treatments for this disease are not effective in all patients showing the need to find new therapeutic targets.Objective:This review aims to update our knowledge on the involvement of astroglial gap junctions and hemichannels in MDD and to show how they have become potential targets for the treatment of this pathology.Methods:The method applied in this review includes a systematic compilation of the relevant literature.Results and Conclusion:The use of rodent models of depression, gene analysis of hippocampal tissues of MDD patients and post-mortem studies on the brains from MDD patients suggest that astrocytic gap junction dysfunction may be a part of MDD etiologies. Chronic antidepressant treatments of rats, rat cultured cortical astrocytes and human astrocytoma cell lines support the hypothesis that the up-regulation of gap junctional coupling between astrocytes could be an underlying mechanism for the therapeutic effect of antidepressants. However, two recent functional studies suggest that connexin43 hemichannel activity is a part of several antidepressants’ mode of action and that astrocyte gap junctional intercellular communication and hemichannels exert different effects on antidepressant drug response. Even if they emerge as new therapeutic targets for new and more active treatments, further studies are needed to decipher the sophisticated and respective role of astrocytic gap junctions and hemichannels in MDD.
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Affiliation(s)
- Denis Sarrouilhe
- Laboratoire de Physiologie Humaine, Faculte de Medecine et Pharmacie, Universite de Poitiers, 6 rue de la Miletrie, Bat D1, TSA 51115, 86073 Poitiers, Cedex 9, France
| | - Marc Mesnil
- STIM, ERL 7003, CNRS-Universite de Poitiers, Pole Biologie Sante, Bat B36, TSA 51106, 1 rue Georges Bonnet, 86073 Poitiers, Cedex 9, France
| | - Catherine Dejean
- Service Pharmacie, Pavillon Janet, Centre Hospitalier Henri Laborit, 370 avenue Jacques Coeur, 86021 Poitiers Cedex, France
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16
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Nazıroğlu M, Çiğ B, Yazğan Y, Schwaerzer GK, Theilig F, Pecze L. Albumin evokes Ca 2+-induced cell oxidative stress and apoptosis through TRPM2 channel in renal collecting duct cells reduced by curcumin. Sci Rep 2019; 9:12403. [PMID: 31455864 PMCID: PMC6711968 DOI: 10.1038/s41598-019-48716-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 07/16/2019] [Indexed: 12/14/2022] Open
Abstract
In proteinuric nephropathies of chronic kidney disease, the epithelial cells of the nephron including the collecting duct are exposed to high concentrations of luminal albumin. Albumin is taken up from collecting duct cells by endocytosis causing excessive reactive oxygen species (ROS) production and a proinflammatory response. Curcumin used in the traditional medicine possesses anti-inflammatory and antioxidant effects. ROS and ADP-ribose (ADPR) activate the cation channel TRPM2. We hypothesize, that albumin-induced cell stress and proinflammatory response are mediated by Ca2+ and can be reduced by curcumin. The cortical collecting duct (CCD) cells mpkCCDc14 exhibit spontaneous and inducible Ca2+ oscillations, which can be blocked by pre-treatment with curcumin. Curcumin accumulates in plasma membrane and intracellular vesicles, where it interferes with TRPM2 and decreases the influx of Ca2+. Albumin reduces cell viability and increases apoptosis, NF-κB activation, and mitochondrial membrane depolarization via Ca2+-dependent signaling, which results in increased ROS production. Albumin-induced cell stress is diminished by the inhibition of TRPM2 after administration of curcumin and ADPR (PARP1) inhibitors. Curcumin did not reduce the Ca2+ elevation induced by thapsigargin in Ca2+-free medium, but it reduced the function of store-operated Ca2+ channels and ATP-evoked Ca2+ response. In conclusion, albumin-induced oxidative stress is mediated by Ca2+-dependent signaling via TRPM2 and leads to cell damage and a proinflammatory response, strengthening the role of CCD cells in the progression of chronic kidney disease.
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Affiliation(s)
- Mustafa Nazıroğlu
- Neuroscience Research Center, Suleyman Demirel University, Isparta, Turkey. .,Department of Biophysics, Faculty of Medicine, Suleyman Demirel University, Isparta, Turkey. .,Department of Neuroscience, Health Science Institute, Suleyman Demirel University, Isparta, Turkey.
| | - Bilal Çiğ
- Department of Biophysics, Faculty of Medicine, Suleyman Demirel University, Isparta, Turkey.,Department of Neuroscience, Health Science Institute, Suleyman Demirel University, Isparta, Turkey
| | - Yener Yazğan
- Department of Biophysics, Faculty of Medicine, Suleyman Demirel University, Isparta, Turkey.,Department of Neuroscience, Health Science Institute, Suleyman Demirel University, Isparta, Turkey
| | | | - Franziska Theilig
- Institute of Anatomy, Christian-Albrechts-University of Kiel, Kiel, Germany. .,Anatomy, Department of Medicine, University of Fribourg, Fribourg, Switzerland.
| | - László Pecze
- Anatomy, Department of Medicine, University of Fribourg, Fribourg, Switzerland.,Independent Scientist, Neuchhatel, Switzerland
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17
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Vallon V, Unwin R, Inscho EW, Leipziger J, Kishore BK. Extracellular Nucleotides and P2 Receptors in Renal Function. Physiol Rev 2019; 100:211-269. [PMID: 31437091 DOI: 10.1152/physrev.00038.2018] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The understanding of the nucleotide/P2 receptor system in the regulation of renal hemodynamics and transport function has grown exponentially over the last 20 yr. This review attempts to integrate the available data while also identifying areas of missing information. First, the determinants of nucleotide concentrations in the interstitial and tubular fluids of the kidney are described, including mechanisms of cellular release of nucleotides and their extracellular breakdown. Then the renal cell membrane expression of P2X and P2Y receptors is discussed in the context of their effects on renal vascular and tubular functions. Attention is paid to effects on the cortical vasculature and intraglomerular structures, autoregulation of renal blood flow, tubuloglomerular feedback, and the control of medullary blood flow. The role of the nucleotide/P2 receptor system in the autocrine/paracrine regulation of sodium and fluid transport in the tubular and collecting duct system is outlined together with its role in integrative sodium and fluid homeostasis and blood pressure control. The final section summarizes the rapidly growing evidence indicating a prominent role of the extracellular nucleotide/P2 receptor system in the pathophysiology of the kidney and aims to identify potential therapeutic opportunities, including hypertension, lithium-induced nephropathy, polycystic kidney disease, and kidney inflammation. We are only beginning to unravel the distinct physiological and pathophysiological influences of the extracellular nucleotide/P2 receptor system and the associated therapeutic perspectives.
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Affiliation(s)
- Volker Vallon
- Departments of Medicine and Pharmacology, University of California San Diego & VA San Diego Healthcare System, San Diego, California; Centre for Nephrology, Division of Medicine, University College London, London, United Kingdom; IMED ECD CVRM R&D, AstraZeneca, Gothenburg, Sweden; Department of Medicine, Division of Nephrology, The University of Alabama at Birmingham, Birmingham, Alabama; Department of Biomedicine/Physiology, Aarhus University, Aarhus, Denmark; Departments of Internal Medicine and Nutrition and Integrative Physiology, and Center on Aging, University of Utah Health & Nephrology Research, VA Salt Lake City Healthcare System, Salt Lake City, Utah
| | - Robert Unwin
- Departments of Medicine and Pharmacology, University of California San Diego & VA San Diego Healthcare System, San Diego, California; Centre for Nephrology, Division of Medicine, University College London, London, United Kingdom; IMED ECD CVRM R&D, AstraZeneca, Gothenburg, Sweden; Department of Medicine, Division of Nephrology, The University of Alabama at Birmingham, Birmingham, Alabama; Department of Biomedicine/Physiology, Aarhus University, Aarhus, Denmark; Departments of Internal Medicine and Nutrition and Integrative Physiology, and Center on Aging, University of Utah Health & Nephrology Research, VA Salt Lake City Healthcare System, Salt Lake City, Utah
| | - Edward W Inscho
- Departments of Medicine and Pharmacology, University of California San Diego & VA San Diego Healthcare System, San Diego, California; Centre for Nephrology, Division of Medicine, University College London, London, United Kingdom; IMED ECD CVRM R&D, AstraZeneca, Gothenburg, Sweden; Department of Medicine, Division of Nephrology, The University of Alabama at Birmingham, Birmingham, Alabama; Department of Biomedicine/Physiology, Aarhus University, Aarhus, Denmark; Departments of Internal Medicine and Nutrition and Integrative Physiology, and Center on Aging, University of Utah Health & Nephrology Research, VA Salt Lake City Healthcare System, Salt Lake City, Utah
| | - Jens Leipziger
- Departments of Medicine and Pharmacology, University of California San Diego & VA San Diego Healthcare System, San Diego, California; Centre for Nephrology, Division of Medicine, University College London, London, United Kingdom; IMED ECD CVRM R&D, AstraZeneca, Gothenburg, Sweden; Department of Medicine, Division of Nephrology, The University of Alabama at Birmingham, Birmingham, Alabama; Department of Biomedicine/Physiology, Aarhus University, Aarhus, Denmark; Departments of Internal Medicine and Nutrition and Integrative Physiology, and Center on Aging, University of Utah Health & Nephrology Research, VA Salt Lake City Healthcare System, Salt Lake City, Utah
| | - Bellamkonda K Kishore
- Departments of Medicine and Pharmacology, University of California San Diego & VA San Diego Healthcare System, San Diego, California; Centre for Nephrology, Division of Medicine, University College London, London, United Kingdom; IMED ECD CVRM R&D, AstraZeneca, Gothenburg, Sweden; Department of Medicine, Division of Nephrology, The University of Alabama at Birmingham, Birmingham, Alabama; Department of Biomedicine/Physiology, Aarhus University, Aarhus, Denmark; Departments of Internal Medicine and Nutrition and Integrative Physiology, and Center on Aging, University of Utah Health & Nephrology Research, VA Salt Lake City Healthcare System, Salt Lake City, Utah
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18
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Mironova E, Suliman F, Stockand JD. Renal Na + excretion consequent to pharmacogenetic activation of G q-DREADD in principal cells. Am J Physiol Renal Physiol 2019; 316:F758-F767. [PMID: 30724104 PMCID: PMC6483033 DOI: 10.1152/ajprenal.00612.2018] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 01/31/2019] [Accepted: 01/31/2019] [Indexed: 02/07/2023] Open
Abstract
Stimulation of metabotropic Gq-coupled purinergic P2Y2 receptors decreases activity of the epithelial Na+ channel (ENaC) in renal principal cells of the distal nephron. The physiological consequences of P2Y2 receptor signaling disruption in the P2Y2 receptor knockout mouse are decreased Na+ excretion and increased arterial blood pressure. However, because of the global nature of this knockout model, the quantitative contribution of ENaC and distal nephron compared with that of upstream renal vascular and tubular elements to changes in urinary excretion and arterial blood pressure is obscure. Moreover, it is uncertain whether stimulation of P2Y2 receptor inhibition of ENaC is sufficient to drive renal (urinary) Na+ excretion (UNaV). Here, using a pharmacogenetic approach and selective agonism of the P2Y2 receptor, we test the sufficiency of targeted stimulation of Gq signaling in principal cells of the distal nephron and P2Y2 receptors to increase UNaV. Selective stimulation of the P2Y2 receptor with the ligand MRS2768 decreased ENaC activity in freshly isolated tubules (as assessed by patch-clamp electrophysiology) and increased UNaV (as assessed in metabolic cages). Similarly, selective agonism of hM3Dq-designer receptors exclusively activated by designer drugs (DREADD) restrictively expressed in principal cells of the distal nephron with clozapine- N-oxide decreased ENaC activity and, consequently, increased UNaV. Clozapine- N-oxide, when applied to control littermates, failed to affect ENaC and UNaV. This study represents the first use of pharmacogenetic (DREADD) technology in the renal tubule and demonstrated that selective activation of the P2Y2 receptor and Gq signaling in principal cells is sufficient to promote renal salt excretion.
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Affiliation(s)
- Elena Mironova
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio , San Antonio, Texas
| | - Faroug Suliman
- Division of Nephrology, Department of Internal Medicine, University of Michigan , Ann Arbor, Michigan
| | - James D Stockand
- Department of Cellular and Integrative Physiology, University of Texas Health Science Center at San Antonio , San Antonio, Texas
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19
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Gyarmati G, Kadoya H, Moon JY, Burford JL, Ahmadi N, Gill IS, Hong YK, Dér B, Peti-Peterdi J. Advances in Renal Cell Imaging. Semin Nephrol 2019; 38:52-62. [PMID: 29291762 DOI: 10.1016/j.semnephrol.2017.09.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A great variety of cell imaging technologies are used routinely every day for the investigation of kidney cell types in applications ranging from basic science research to drug development and pharmacology, clinical nephrology, and pathology. Quantitative visualization of the identity, density, and fate of both resident and nonresident cells in the kidney, and imaging-based analysis of their altered function, (patho)biology, metabolism, and signaling in disease conditions, can help to better define pathomechanism-based disease subgroups, identify critical cells and structures that play a role in the pathogenesis, critically needed biomarkers of disease progression, and cell and molecular pathways as targets for novel therapies. Overall, renal cell imaging has great potential for improving the precision of diagnostic and treatment paradigms for individual acute kidney injury or chronic kidney disease patients or patient populations. This review highlights and provides examples for some of the recently developed renal cell optical imaging approaches, mainly intravital multiphoton fluorescence microscopy, and the new knowledge they provide for our better understanding of renal pathologies.
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Affiliation(s)
- Georgina Gyarmati
- Department of Physiology and Neuroscience, Department of Medicine, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Hiroyuki Kadoya
- Department of Physiology and Neuroscience, Department of Medicine, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA; Department of Nephrology and Hypertension, Kawasaki Medical School, Kurashiki, Japan
| | - Ju-Young Moon
- Department of Physiology and Neuroscience, Department of Medicine, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA; Division of Nephrology, Department of Internal Medicine, Kyung Hee University, College of Medicine, Seoul, Korea
| | - James L Burford
- Department of Physiology and Neuroscience, Department of Medicine, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Nariman Ahmadi
- Institute of Urology, Catherine & Joseph Aresty Department of Urology, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Inderbir S Gill
- Institute of Urology, Catherine & Joseph Aresty Department of Urology, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Young-Kwon Hong
- Department of Surgery and Biochemistry and Molecular Biology, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Bálint Dér
- Department of Physiology and Neuroscience, Department of Medicine, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - János Peti-Peterdi
- Department of Physiology and Neuroscience, Department of Medicine, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA.
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20
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Assmus AM, Mansley MK, Mullins LJ, Peter A, Mullins JJ. mCCD cl1 cells show plasticity consistent with the ability to transition between principal and intercalated cells. Am J Physiol Renal Physiol 2017; 314:F820-F831. [PMID: 29357433 DOI: 10.1152/ajprenal.00354.2017] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The cortical collecting duct of the mammalian kidney plays a critical role in the regulation of body volume, sodium pH, and osmolarity and is composed of two distinct cells types, principal cells and intercalated cells. Each cell type is detectable in the kidney by the localization of specific transport proteins such as aquaporin 2 (Aqp2) and epithelial sodium channel (ENaC) in principal cells and V-ATPase B1 and connexin 30 (Cx30) in intercalated cells. mCCDcl1 cells have been widely used as a mouse principal cell line on the basis of their physiological characteristics. In this study, the mCCDcl1 parental cell line and three sublines cloned from isolated single cells (Ed1, Ed2, and Ed3) were grown on filters to assess their transepithelial resistance, transepithelial voltage, equivalent short circuit current and expression of the cell-specific markers Aqp2, ENaC, V-ATPaseB1, and Cx30. The parental mCCDcl1 cell line presented amiloride-sensitive electrogenic sodium transport indicative of principal cell function; however, immunocytochemistry and RT-PCR showed that some cells expressed the intercalated cell-specific markers V-ATPase B1 and Cx30, including a subset of cells also positive for Aqp2 and ENaC. The three subclonal lines contained cells that were positive for both intercalated and principal cell-specific markers. The vertical transmission of both principal and intercalated cell characteristics via single cell cloning reveals the plasticity of mCCDcl1 cells and a direct lineage relationship between these two physiologically important cell types and is consistent with mCCDcl1 cells being precursor cells.
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Affiliation(s)
- A M Assmus
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh , Edinburgh , United Kingdom
| | - M K Mansley
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh , Edinburgh , United Kingdom
| | - L J Mullins
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh , Edinburgh , United Kingdom
| | - A Peter
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh , Edinburgh , United Kingdom
| | - J J Mullins
- University of Edinburgh/British Heart Foundation Centre for Cardiovascular Science, The University of Edinburgh , Edinburgh , United Kingdom
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21
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Mazaré N, Gilbert A, Boulay AC, Rouach N, Cohen-Salmon M. Connexin 30 is expressed in a subtype of mouse brain pericytes. Brain Struct Funct 2017; 223:1017-1024. [PMID: 29143947 DOI: 10.1007/s00429-017-1562-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 11/02/2017] [Indexed: 12/11/2022]
Abstract
Pericytes are mural cells of blood microvessels which play a crucial role at the neurovascular interface of the central nervous system. They are involved in the regulation of blood-brain barrier integrity, angiogenesis, clearance of toxic metabolites, capillary hemodynamic responses, and neuroinflammation, and they demonstrate stem cell activity. Morphological and molecular studies to characterize brain pericytes recently pointed out some heterogeneity in pericyte population. Nevertheless, a clear definition of pericyte subtypes is still lacking. Here, we demonstrate that a fraction of brain pericytes express Connexin 30 (Cx30), a gap junction protein, which, in the brain parenchyma, was thought to be exclusively found in astrocytes. Cx30 could thus be a candidate protein in the composition of the gap junction channels already described between endothelial cells and pericytes. It could also form hemichannels or acts in a channel-independent manner to regulate pericyte morphology, as already observed in astrocytes. Altogether, our results suggest that Cx30 defines a novel brain pericyte subtype.
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Affiliation(s)
- Noémie Mazaré
- Collège de France, Center for Interdisciplinary Research in Biology (CIRB)/Centre National de La Recherche Scientifique CNRS, Unité Mixte de Recherche 7241/Institut National de la Santé et de la Recherche Médicale INSERM, U1050/Neuroglial Interactions in Cerebral Physiopathology, 75231, Paris Cedex 05, France.,University Pierre et Marie Curie, ED, N°158, 75005, Paris, France.,MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, 75005, Paris, France
| | - Alice Gilbert
- Collège de France, Center for Interdisciplinary Research in Biology (CIRB)/Centre National de La Recherche Scientifique CNRS, Unité Mixte de Recherche 7241/Institut National de la Santé et de la Recherche Médicale INSERM, U1050/Neuroglial Interactions in Cerebral Physiopathology, 75231, Paris Cedex 05, France.,University Pierre et Marie Curie, ED, N°158, 75005, Paris, France.,MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, 75005, Paris, France
| | - Anne-Cécile Boulay
- Collège de France, Center for Interdisciplinary Research in Biology (CIRB)/Centre National de La Recherche Scientifique CNRS, Unité Mixte de Recherche 7241/Institut National de la Santé et de la Recherche Médicale INSERM, U1050/Neuroglial Interactions in Cerebral Physiopathology, 75231, Paris Cedex 05, France.,University Pierre et Marie Curie, ED, N°158, 75005, Paris, France.,MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, 75005, Paris, France
| | - Nathalie Rouach
- Collège de France, Center for Interdisciplinary Research in Biology (CIRB)/Centre National de La Recherche Scientifique CNRS, Unité Mixte de Recherche 7241/Institut National de la Santé et de la Recherche Médicale INSERM, U1050/Neuroglial Interactions in Cerebral Physiopathology, 75231, Paris Cedex 05, France.,University Pierre et Marie Curie, ED, N°158, 75005, Paris, France.,MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, 75005, Paris, France
| | - Martine Cohen-Salmon
- Collège de France, Center for Interdisciplinary Research in Biology (CIRB)/Centre National de La Recherche Scientifique CNRS, Unité Mixte de Recherche 7241/Institut National de la Santé et de la Recherche Médicale INSERM, U1050/Neuroglial Interactions in Cerebral Physiopathology, 75231, Paris Cedex 05, France. .,University Pierre et Marie Curie, ED, N°158, 75005, Paris, France. .,MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, 75005, Paris, France.
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22
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Abstract
PURPOSE OF REVIEW The review aims to provide a brief summary and evaluation of the current state of research that uses multiphoton fluorescence microscopy for intravital kidney imaging. RECENT FINDINGS Direct visualization of the glomerular filter, proximal and distal tubule segments, and the renal vasculature in the living, intact kidney in zebrafish, mouse, and rat models with high temporal and spatial resolution provided new insights into the function of the normal and diseased kidney. New technical developments in fluorescence excitation and detection, in combination with transgenic animal models for cell function and fate mapping, and serial imaging of the same glomerulus in the same animal over several days further advanced the field of nephrology research, and the understanding of disease mechanisms. SUMMARY Intravital multiphoton imaging has solved many critical technical barriers in kidney research and allowed the dynamic portrayal of the structure and function of various renal cell types in vivo. It has become a widely used research technique, with significant past achievements, and tremendous potential for future development and applications for the study and better understanding of kidney diseases.
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23
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Carrisoza-Gaytán R, Wang L, Schreck C, Kleyman TR, Wang WH, Satlin LM. The mechanosensitive BKα/β1 channel localizes to cilia of principal cells in rabbit cortical collecting duct (CCD). Am J Physiol Renal Physiol 2016; 312:F143-F156. [PMID: 27806944 DOI: 10.1152/ajprenal.00256.2016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Revised: 10/12/2016] [Accepted: 10/26/2016] [Indexed: 11/22/2022] Open
Abstract
Within the CCD of the distal nephron of the rabbit, the BK (maxi K) channel mediates Ca2+- and/or stretch-dependent flow-induced K+ secretion (FIKS) and contributes to K+ adaptation in response to dietary K+ loading. An unresolved question is whether BK channels in intercalated cells (ICs) and/or principal cells (PCs) in the CCD mediate these K+ secretory processes. In support of a role for ICs in FIKS is the higher density of immunoreactive apical BKα (pore-forming subunit) and functional BK channel activity than detected in PCs, and an increase in IC BKα expression in response to a high-K+ diet. PCs possess a single apical cilium which has been proposed to serve as a mechanosensor; direct manipulation of cilia leads to increases in cell Ca2+ concentration, albeit of nonciliary origin. Immunoperfusion of isolated and fixed CCDs isolated from control K+-fed rabbits with channel subunit-specific antibodies revealed colocalization of immunodetectable BKα- and β1-subunits in cilia as well as on the apical membrane of cilia-expressing PCs. Ciliary BK channels were more easily detected in rabbits fed a low-K+ vs. high-K+ diet. Single-channel recordings of cilia revealed K+ channels with conductance and kinetics typical of the BK channel. The observations that 1) FIKS was preserved but 2) the high-amplitude Ca2+ peak elicited by flow was reduced in microperfused CCDs subject to pharmacological deciliation suggest that cilia BK channels do not contribute to K+ secretion in this segment, but that cilia serve as modulators of cell signaling.
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Affiliation(s)
| | - Lijun Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Carlos Schreck
- Servicio de Nefrologia-Hospital Italiano de Buenos Aires, Buenos Aires, Argentina
| | - Thomas R Kleyman
- Departments of Medicine, Cell Biology, and Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, Pennsylvania; and
| | - Wen-Hui Wang
- Department of Pharmacology, New York Medical College, Valhalla, New York
| | - Lisa M Satlin
- Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York;
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24
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Ilatovskaya DV, Palygin O, Staruschenko A. Functional and therapeutic importance of purinergic signaling in polycystic kidney disease. Am J Physiol Renal Physiol 2016; 311:F1135-F1139. [PMID: 27654892 DOI: 10.1152/ajprenal.00406.2016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 09/20/2016] [Indexed: 12/12/2022] Open
Abstract
Polycystic kidney diseases (PKD) are a group of inherited nephropathies marked with the formation of fluid-filled cysts along the nephron. This renal disorder affects millions of people worldwide, but current treatment strategies are unfortunately limited to supportive therapy, dietary restrictions, and, eventually, renal transplantation. Recent advances in PKD management are aimed at targeting exaggerated cell proliferation and dedifferentiation to interfere with cyst growth. However, not nearly enough is known about the ion transport properties of the cystic cells, or specific signaling pathways modulating channels and transporters in this condition. There is growing evidence that abnormally elevated concentrations of adenosine triphosphate (ATP) in PKD may contribute to cyst enlargement; change in the profile of purinergic receptors may also result in promotion of cystogenesis. The current mini-review is focused on the role of ATP and associated signaling affecting ion transport properties of the renal cystic epithelia.
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Affiliation(s)
- Daria V Ilatovskaya
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Oleg Palygin
- Department of Physiology, Medical College of Wisconsin, Milwaukee, Wisconsin
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25
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Boulay AC, Cisternino S, Cohen-Salmon M. Immunoregulation at the gliovascular unit in the healthy brain: A focus on Connexin 43. Brain Behav Immun 2016; 56:1-9. [PMID: 26674996 DOI: 10.1016/j.bbi.2015.11.017] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 10/26/2015] [Accepted: 11/28/2015] [Indexed: 01/18/2023] Open
Abstract
In the brain, immune cell infiltration is normally kept at a very low level and a unique microenvironment strictly restricts immune reactions and inflammation. Even in such quiescent environment, a constant immune surveillance is at work allowing the brain to rapidly react to threats. To date, knowledge about the factors regulating the brain-immune system interrelationship in healthy conditions remains elusive. Interestingly, astrocytes, the most abundant glial cells in the brain, may participate in many aspects of this unique homeostasis, in particular due to their close interaction with the brain vascular system and expression of a specific molecular repertoire. Indeed, astrocytes maintain the blood-brain barrier (BBB) integrity, interact with immune cells, and participate in the regulation of intracerebral liquid movements. We recently showed that Connexin 43 (Cx43), a gap junction protein highly expressed by astrocytes at the BBB interface, is an immunoregulating factor. The absence of astroglial Cx43 leads to a transient endothelial activation, a continuous immune recruitment as well as the development of a specific humoral autoimmune response against the von Willebrand factor A domain-containing protein 5a, an extracellular matrix protein expressed by astrocytes. In this review, we propose to gather current knowledge on how astrocytes may influence the immune system in the healthy brain, focusing on their roles at the gliovascular interface. We will also consider pathological situations involving astrocyte-specific autoimmunities. Finally, we will discuss the specific role of astroglial Cx43 and the physiological consequences of immune regulations taking place on inflammation, cognition and behavior in the absence of Cx43.
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Affiliation(s)
- Anne-Cécile Boulay
- Collège de France, Center for Interdisciplinary Research in Biology (CIRB), Centre National de la Recherche Scientifique CNRS, Unité Mixte de Recherche 7241, Institut National de la Santé et de la Recherche Médicale INSERM, U1050, Neuroglial Interactions in Cerebral Physiopathology, 75231 Paris Cedex 05, France; University Pierre et Marie Curie, ED, N°158, 75005 Paris, France; MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, 75005 Paris, France
| | - Salvatore Cisternino
- Variabilité de réponse aux psychotropes, INSERM, U1144, Paris F-75006, France; Université Paris Descartes, Faculté de Pharmacie, UMR-S 1144, 75006 Paris, France; Université Paris Diderot, UMR-S 1144, 75013 Paris, France
| | - Martine Cohen-Salmon
- Collège de France, Center for Interdisciplinary Research in Biology (CIRB), Centre National de la Recherche Scientifique CNRS, Unité Mixte de Recherche 7241, Institut National de la Santé et de la Recherche Médicale INSERM, U1050, Neuroglial Interactions in Cerebral Physiopathology, 75231 Paris Cedex 05, France; University Pierre et Marie Curie, ED, N°158, 75005 Paris, France; MEMOLIFE Laboratory of Excellence and Paris Science Lettre Research University, 75005 Paris, France.
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26
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Abstract
PURPOSE OF REVIEW The proximal tubule plays a critical role in the reabsorption of ions, solutes and low molecular weight proteins from the glomerular filtrate. Although the proximal tubule has long been known to acutely modulate ion reabsorption in response to changes in flow rates of the glomerular filtrate, it has only recently been discovered that proximal tubule cells can similarly adjust endocytic capacity in response to flow. This review synthesizes our current understanding of mechanosensitive regulation of endocytic capacity in proximal tubule epithelia and highlights areas of opportunity for future investigations. RECENT FINDINGS Recent studies have reported that the endocytic capacity of proximal tubule cells is dramatically increased upon exposure to flow and the accompanying fluid shear stress. Modulation of this pathway is dependent on increases in intracellular calcium initiated by bending of the primary cilium, and also requires purinergic receptor activation that is mediated by release of extracellular ATP. This article summarizes what is currently known about the signaling cascade that transduces changes in flow into alterations in endocytosis. We discuss the implications of this newly described regulatory pathway with respect to our understanding of protein retrieval by the kidney under normal conditions, and in diseases that present with low molecular weight proteinuria. SUMMARY Primary cilia act as mechanotransducers that modulate apical endocytic capacity in proximal tubule cells in response to changes in fluid shear stress.
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27
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García IE, Bosen F, Mujica P, Pupo A, Flores-Muñoz C, Jara O, González C, Willecke K, Martínez AD. From Hyperactive Connexin26 Hemichannels to Impairments in Epidermal Calcium Gradient and Permeability Barrier in the Keratitis-Ichthyosis-Deafness Syndrome. J Invest Dermatol 2016; 136:574-583. [PMID: 26777423 DOI: 10.1016/j.jid.2015.11.017] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Revised: 11/05/2015] [Accepted: 11/06/2015] [Indexed: 01/19/2023]
Abstract
The keratitis-ichthyosis-deafness (KID) syndrome is characterized by corneal, skin, and hearing abnormalities. KID has been linked to heterozygous dominant missense mutations in the GJB2 and GJB6 genes, encoding connexin26 and 30, respectively. In vitro evidence indicates that KID mutations lead to hyperactive (open) hemichannels, which in some cases is accompanied by abnormal function of gap junction channels. Transgenic mouse models expressing connexin26 KID mutations reproduce human phenotypes and present impaired epidermal calcium homeostasis and abnormal lipid composition of the stratum corneum affecting the water barrier. Here we have compiled relevant data regarding the KID syndrome and propose a mechanism for the epidermal aspects of the disease.
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Affiliation(s)
- Isaac E García
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Felicitas Bosen
- LIMES (Life and Medical Sciences) Institute, University of Bonn, Bonn, Germany
| | - Paula Mujica
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Amaury Pupo
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Carolina Flores-Muñoz
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Oscar Jara
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Carlos González
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
| | - Klaus Willecke
- LIMES (Life and Medical Sciences) Institute, University of Bonn, Bonn, Germany.
| | - Agustín D Martínez
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile.
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28
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Sala G, Badalamenti S, Ponticelli C. The Renal Connexome and Possible Roles of Connexins in Kidney Diseases. Am J Kidney Dis 2015; 67:677-87. [PMID: 26613807 DOI: 10.1053/j.ajkd.2015.09.030] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Accepted: 09/30/2015] [Indexed: 12/21/2022]
Abstract
Connexins are membrane-spanning proteins that allow for the formation of cell-to-cell channels and cell-to-extracellular space hemichannels. Many connexin subtypes are expressed in kidney cells. Some mutations in connexin genes have been linked to various human pathologies, including cardiovascular, neurodegenerative, lung, and skin diseases, but the exact role of connexins in kidney disease remains unclear. Some hypotheses about a connection between genetic mutations, endoplasmic reticulum (ER) stress, and the unfolded protein response (UPR) in kidney pathology have been explored. The potential relationship of kidney disease to abnormal production of connexin proteins, mutations in their genes together with ER stress, or the UPR is still a matter of debate. In this scenario, it is tantalizing to speculate about a possible role of connexins in the setting of kidney pathologies that are thought to be caused by a deregulated podocyte protein expression, the so-called podocytopathies. In this article, we give examples of the roles of connexins in kidney (patho)physiology and propose avenues for further research concerning connexins, ER stress, and UPR in podocytopathies that may ultimately help refine drug treatment.
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Affiliation(s)
- Gabriele Sala
- Nephrology and Dialysis Unit, Humanitas Clinical Research Center, Rozzano (Milano), Italy.
| | - Salvatore Badalamenti
- Nephrology and Dialysis Unit, Humanitas Clinical Research Center, Rozzano (Milano), Italy
| | - Claudio Ponticelli
- Nephrology and Dialysis Unit, Humanitas Clinical Research Center, Rozzano (Milano), Italy
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29
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Retamal MA, Reyes EP, García IE, Pinto B, Martínez AD, González C. Diseases associated with leaky hemichannels. Front Cell Neurosci 2015; 9:267. [PMID: 26283912 PMCID: PMC4515567 DOI: 10.3389/fncel.2015.00267] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 06/29/2015] [Indexed: 01/10/2023] Open
Abstract
Hemichannels (HCs) and gap junction channels (GJCs) formed by protein subunits called connexins (Cxs) are major pathways for intercellular communication. While HCs connect the intracellular compartment with the extracellular milieu, GJCs allow the interchange of molecules between cytoplasm of two contacting cells. Under physiological conditions, HCs are mostly closed, but they can open under certain stimuli allowing the release of autocrine and paracrine molecules. Moreover, some pathological conditions, like ischemia or other inflammation conditions, significantly increase HCs activity. In addition, some mutations in Cx genes associated with human diseases, such as deafness or cataracts, lead to the formation of more active HCs or “leaky HCs.” In this article we will revise cellular and molecular mechanisms underlying the appearance of leaky HCs, and the consequences of their expression in different cellular systems and animal models, in seeking a common pattern or pathological mechanism of disease.
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Affiliation(s)
- Mauricio A Retamal
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo Santiago, Chile
| | - Edison P Reyes
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo Santiago, Chile ; Centro de Investigación Biomédica, Universidad Autónoma de Chile Santiago, Chile
| | - Isaac E García
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso Valparaíso, Chile
| | - Bernardo Pinto
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso Valparaíso, Chile
| | - Agustín D Martínez
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso Valparaíso, Chile
| | - Carlos González
- Centro Interdisciplinario de Neurociencia de Valparaíso, Instituto de Neurociencia, Facultad de Ciencias, Universidad de Valparaíso Valparaíso, Chile
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30
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Kishore BK, Carlson NG, Ecelbarger CM, Kohan DE, Müller CE, Nelson RD, Peti-Peterdi J, Zhang Y. Targeting renal purinergic signalling for the treatment of lithium-induced nephrogenic diabetes insipidus. Acta Physiol (Oxf) 2015; 214:176-88. [PMID: 25877068 PMCID: PMC4430398 DOI: 10.1111/apha.12507] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 04/08/2015] [Indexed: 12/26/2022]
Abstract
Lithium still retains its critical position in the treatment of bipolar disorder by virtue of its ability to prevent suicidal tendencies. However, chronic use of lithium is often limited by the development of nephrogenic diabetes insipidus (NDI), a debilitating condition. Lithium-induced NDI is due to resistance of the kidney to arginine vasopressin (AVP), leading to polyuria, natriuresis and kaliuresis. Purinergic signalling mediated by extracellular nucleotides (ATP/UTP), acting via P2Y receptors, opposes the action of AVP on renal collecting duct (CD) by decreasing the cellular cAMP and thus AQP2 protein levels. Taking a cue from this phenomenon, we discovered the potential involvement of ATP/UTP-activated P2Y2 receptor in lithium-induced NDI in rats and showed that P2Y2 receptor knockout mice are significantly resistant to Li-induced polyuria, natriuresis and kaliuresis. Extension of these studies revealed that ADP-activated P2Y12 receptor is expressed in the kidney, and its irreversible blockade by the administration of clopidogrel bisulphate (Plavix(®)) ameliorates Li-induced NDI in rodents. Parallel in vitro studies showed that P2Y12 receptor blockade by the reversible antagonist PSB-0739 sensitizes CD to the action of AVP. Thus, our studies unravelled the potential beneficial effects of targeting P2Y2 or P2Y12 receptors to counter AVP resistance in lithium-induced NDI. If established in further studies, our findings may pave the way for the development of better and safer methods for the treatment of NDI by bringing a paradigm shift in the approach from the current therapies that predominantly counter the anti-AVP effects to those that enhance the sensitivity of the kidney to AVP action.
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Affiliation(s)
- B. K. Kishore
- Department of Internal Medicine, University of Utah Health Sciences Center, Salt Lake City, Utah, USA
- Nephrology Research, Department of Veterans Affairs Salt Lake City Health Care System, Salt Lake City, Utah, USA
- Center on Aging, University of Utah Health Sciences Center, Salt Lake City, Utah, USA
| | - N. G. Carlson
- Center on Aging, University of Utah Health Sciences Center, Salt Lake City, Utah, USA
- Department of Neurobiology and Anatomy, University of Utah Health Sciences Center, Salt Lake City, Utah, USA
- Geriatric Research, Education and Clinical Center, Department of Veterans Affairs Salt Lake City Health Care System, Salt Lake City, Utah, USA
| | - C. M. Ecelbarger
- Department of Medicine, Georgetown University, Washington, District of Columbia, USA
- Center for the Study of Sex Differences in Health, Aging, and Disease, Georgetown University, Washington, District of Columbia, USA
| | - D. E. Kohan
- Department of Internal Medicine, University of Utah Health Sciences Center, Salt Lake City, Utah, USA
- Nephrology Research, Department of Veterans Affairs Salt Lake City Health Care System, Salt Lake City, Utah, USA
| | - C. E. Müller
- PharmaCenter Bonn, Pharmaceutical Institute, Pharmaceutical Chemistry I, University of Bonn, Bonn, Germany
| | - R. D. Nelson
- Department of Paediatrics, University of Utah Health Sciences Center, Salt Lake City, Utah, USA
| | - J. Peti-Peterdi
- Department of Physiology and Biophysics, and Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, California, USA
| | - Y. Zhang
- Department of Internal Medicine, University of Utah Health Sciences Center, Salt Lake City, Utah, USA
- Nephrology Research, Department of Veterans Affairs Salt Lake City Health Care System, Salt Lake City, Utah, USA
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31
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Retamal MA, León-Paravic CG, Ezquer M, Ezquer F, Rio RD, Pupo A, Martínez AD, González C. Carbon monoxide: A new player in the redox regulation of connexin hemichannels. IUBMB Life 2015; 67:428-37. [DOI: 10.1002/iub.1388] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 05/05/2015] [Indexed: 01/23/2023]
Affiliation(s)
- Mauricio A. Retamal
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina; Clínica Alemana Universidad del Desarrollo; Santiago Chile
| | - Carmen G. León-Paravic
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina; Clínica Alemana Universidad del Desarrollo; Santiago Chile
| | - Marcelo Ezquer
- Centro de Medicina Regenerativa, Facultad de Medicina; Clínica Alemana Universidad del Desarrollo; Santiago Chile
| | - Fernando Ezquer
- Centro de Medicina Regenerativa, Facultad de Medicina; Clínica Alemana Universidad del Desarrollo; Santiago Chile
| | - Rodrigo Del Rio
- Centro de Investigación Biomédica; Universidad Autónoma de Chile; Santiago Chile
| | - Amaury Pupo
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias; Instituto de Neurociencia; Universidad de Valparaíso; Valparaíso Chile
| | - Agustín D. Martínez
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias; Instituto de Neurociencia; Universidad de Valparaíso; Valparaíso Chile
| | - Carlos González
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias; Instituto de Neurociencia; Universidad de Valparaíso; Valparaíso Chile
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32
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Hall AM, Molitoris BA. Dynamic multiphoton microscopy: focusing light on acute kidney injury. Physiology (Bethesda) 2015; 29:334-42. [PMID: 25180263 DOI: 10.1152/physiol.00010.2014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Acute kidney injury (AKI) is a major global health problem; much research has been conducted on AKI, and numerous agents have shown benefit in animal studies, but none have translated into treatments. There is, therefore, a pressing unmet need to increase knowledge of the pathophysiology of AKI. Multiphoton microscopy (MPM) provides a tool to non-invasively visualize dynamic events in real time and at high resolution in rodent kidneys, and in this article we review its application to study novel mechanisms and treatments in different forms of AKI.
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Affiliation(s)
- Andrew M Hall
- Institute of Anatomy, University of Zurich, Zurich, Switzerland; and
| | - Bruce A Molitoris
- Indiana University School of Medicine, Indiana Center for Biological Microscopy, Indianapolis, Indiana
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33
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Persson AEG, Carlström M. Renal purinergic signalling in health and disease. Acta Physiol (Oxf) 2015; 213:805-7. [PMID: 25613023 DOI: 10.1111/apha.12459] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Affiliation(s)
- A. E. G. Persson
- Department of Medical Cellbiology; Uppsala University; Uppsala Sweden
| | - M. Carlström
- Department of Physiology and Pharmacology; Karolinska Institutet; Stockholm Sweden
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34
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Szebényi K, Füredi A, Kolacsek O, Csohány R, Prókai Á, Kis-Petik K, Szabó A, Bősze Z, Bender B, Tóvári J, Enyedi Á, Orbán TI, Apáti Á, Sarkadi B. Visualization of Calcium Dynamics in Kidney Proximal Tubules. J Am Soc Nephrol 2015; 26:2731-40. [PMID: 25788535 DOI: 10.1681/asn.2014070705] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 01/08/2015] [Indexed: 12/28/2022] Open
Abstract
Intrarenal changes in cytoplasmic calcium levels have a key role in determining pathologic and pharmacologic responses in major kidney diseases. However, cell-specific delivery of calcium-sensitive probes in vivo remains problematic. We generated a transgenic rat stably expressing the green fluorescent protein-calmodulin-based genetically encoded calcium indicator (GCaMP2) predominantly in the kidney proximal tubules. The transposon-based method used allowed the generation of homozygous transgenic rats containing one copy of the transgene per allele with a defined insertion pattern, without genetic or phenotypic alterations. We applied in vitro confocal and in vivo two-photon microscopy to examine basal calcium levels and ligand- and drug-induced alterations in these levels in proximal tubular epithelial cells. Notably, renal ischemia induced a transient increase in cellular calcium, and reperfusion resulted in a secondary calcium load, which was significantly decreased by systemic administration of specific blockers of the angiotensin receptor and the Na-Ca exchanger. The parallel examination of in vivo cellular calcium dynamics and renal circulation by fluorescent probes opens new possibilities for physiologic and pharmacologic investigations.
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Affiliation(s)
- Kornélia Szebényi
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - András Füredi
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - Orsolya Kolacsek
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | | | | | - Katalin Kis-Petik
- Department of Biophysics and Radiation Biology, MTA-SE Molecular Biophysics Research Group, and
| | - Attila Szabó
- MTA-SE, Pediatrics and Nephrology Research Group, Budapest, Hungary
| | | | | | - József Tóvári
- Department of Experimental Pharmacology, National Institute of Oncology, Budapest, Hungary
| | - Ágnes Enyedi
- Second Department of Pathology, Semmelweis University, Budapest, Hungary
| | - Tamás I Orbán
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - Ágota Apáti
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary;
| | - Balázs Sarkadi
- Institute of Enzymology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary; Department of Biophysics and Radiation Biology, MTA-SE Molecular Biophysics Research Group, and
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Muñoz MF, Puebla M, Figueroa XF. Control of the neurovascular coupling by nitric oxide-dependent regulation of astrocytic Ca(2+) signaling. Front Cell Neurosci 2015; 9:59. [PMID: 25805969 PMCID: PMC4354411 DOI: 10.3389/fncel.2015.00059] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 02/07/2015] [Indexed: 12/28/2022] Open
Abstract
Neuronal activity must be tightly coordinated with blood flow to keep proper brain function, which is achieved by a mechanism known as neurovascular coupling. Then, an increase in synaptic activity leads to a dilation of local parenchymal arterioles that matches the enhanced metabolic demand. Neurovascular coupling is orchestrated by astrocytes. These glial cells are located between neurons and the microvasculature, with the astrocytic endfeet ensheathing the vessels, which allows fine intercellular communication. The neurotransmitters released during neuronal activity reach astrocytic receptors and trigger a Ca2+ signaling that propagates to the endfeet, activating the release of vasoactive factors and arteriolar dilation. The astrocyte Ca2+ signaling is coordinated by gap junction channels and hemichannels formed by connexins (Cx43 and Cx30) and channels formed by pannexins (Panx-1). The neuronal activity-initiated Ca2+ waves are propagated among neighboring astrocytes directly via gap junctions or through ATP release via connexin hemichannels or pannexin channels. In addition, Ca2+ entry via connexin hemichannels or pannexin channels may participate in the regulation of the astrocyte signaling-mediated neurovascular coupling. Interestingly, nitric oxide (NO) can activate connexin hemichannel by S-nitrosylation and the Ca2+-dependent NO-synthesizing enzymes endothelial NO synthase (eNOS) and neuronal NOS (nNOS) are expressed in astrocytes. Therefore, the astrocytic Ca2+ signaling triggered in neurovascular coupling may activate NO production, which, in turn, may lead to Ca2+ influx through hemichannel activation. Furthermore, NO release from the hemichannels located at astrocytic endfeet may contribute to the vasodilation of parenchymal arterioles. In this review, we discuss the mechanisms involved in the regulation of the astrocytic Ca2+ signaling that mediates neurovascular coupling, with a special emphasis in the possible participation of NO in this process.
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Affiliation(s)
- Manuel F Muñoz
- Facultad de Ciencias Biológicas, Departamento de Fisiología, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Mariela Puebla
- Facultad de Ciencias Biológicas, Departamento de Fisiología, Pontificia Universidad Católica de Chile Santiago, Chile
| | - Xavier F Figueroa
- Facultad de Ciencias Biológicas, Departamento de Fisiología, Pontificia Universidad Católica de Chile Santiago, Chile
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Novel in vivo techniques to visualize kidney anatomy and function. Kidney Int 2015; 88:44-51. [PMID: 25738253 PMCID: PMC4490063 DOI: 10.1038/ki.2015.65] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2014] [Revised: 01/05/2015] [Accepted: 01/06/2015] [Indexed: 12/11/2022]
Abstract
Intravital imaging using multiphoton microscopy (MPM) has become an increasingly popular and widely used experimental technique in kidney research over the past few years. MPM allows deep optical sectioning of the intact, living kidney tissue with submicron resolution which is unparalleled among intravital imaging approaches. MPM has solved a long-standing critical technical barrier in renal research to study several complex and inaccessible cell types and anatomical structures in vivo in their native environment. Comprehensive and quantitative kidney structure and function MPM studies helped our better understanding of the cellular and molecular mechanisms of the healthy and diseased kidney. This review summarizes recent in vivo MPM studies with a focus on the glomerulus and the filtration barrier, although select, glomerulus-related renal vascular and tubular functions are also mentioned. The latest applications of serial MPM of the same glomerulus in vivo, in the intact kidney over several days, during the progression of glomerular disease are discussed. This visual approach, in combination with genetically encoded fluorescent markers of cell lineage, has helped to track the fate and function (e.g. cell calcium changes) of single podocytes during the development of glomerular pathologies, and provided visual proof for the highly dynamic rather than static nature of the glomerular environment. Future intravital imaging applications have the promise to further push the limits of optical microscopy, and to advance our understanding of the mechanisms of kidney injury. Also, MPM will help to study new mechanisms of tissue repair and regeneration, a cutting edge area of kidney research.
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Mamenko M, Zaika O, Boukelmoune N, O'Neil RG, Pochynyuk O. Deciphering physiological role of the mechanosensitive TRPV4 channel in the distal nephron. Am J Physiol Renal Physiol 2015; 308:F275-86. [PMID: 25503733 PMCID: PMC4329491 DOI: 10.1152/ajprenal.00485.2014] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2014] [Accepted: 12/08/2014] [Indexed: 12/14/2022] Open
Abstract
Long-standing experimental evidence suggests that epithelial cells in the renal tubule are able to sense osmotic and pressure gradients caused by alterations in ultrafiltrate flow by elevating intracellular Ca(2+) concentration. These responses are viewed as critical regulators of a variety of processes ranging from transport of water and solutes to cellular growth and differentiation. A loss in the ability to sense mechanical stimuli has been implicated in numerous pathologies associated with systemic imbalance of electrolytes and to the development of polycystic kidney disease. The molecular mechanisms conferring mechanosensitive properties to epithelial tubular cells involve activation of transient receptor potential (TRP) channels, such as TRPV4, allowing direct Ca(2+) influx to increase intracellular Ca(2+) concentration. In this review, we critically analyze the current evidence about signaling determinants of TRPV4 activation by luminal flow in the distal nephron and discuss how dysfunction of this mechanism contributes to the progression of polycystic kidney disease. We also review the physiological relevance of TRPV4-based mechanosensitivity in controlling flow-dependent K(+) secretion in the distal renal tubule.
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Affiliation(s)
- M Mamenko
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas
| | - O Zaika
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas
| | - N Boukelmoune
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas
| | - R G O'Neil
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas
| | - O Pochynyuk
- Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas
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Hills CE, Price GW, Squires PE. Mind the gap: connexins and cell-cell communication in the diabetic kidney. Diabetologia 2015; 58:233-41. [PMID: 25358446 DOI: 10.1007/s00125-014-3427-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 09/25/2014] [Indexed: 10/24/2022]
Abstract
Connexins, assembled as a hexameric connexon, form a transmembrane hemichannel that provides a conduit for paracrine signalling of small molecules and ions to regulate the activity and function of adjacent cells. When hemichannels align and associate with similar channels on opposing cells, they form a continuous aqueous pore or gap junction, allowing the direct transmission of metabolic and electrical signals between coupled cells. Regulation of gap junction synthesis and channel activity is critical for cell function, and a number of diseases can be attributed to changes in the expression/function of these important proteins. Diabetic nephropathy is associated with several complex metabolic and inflammatory responses characterised by defects at the molecular, cellular and tissue level. In both type 1 and type 2 diabetes, glycaemic injury of the kidney is the leading cause of end-stage renal failure, a consequence of multiple aetiologies, including increased deposition of extracellular matrix, glomerular hyperfiltration, albuminuria and tubulointerstitial fibrosis. In diabetic nephropathy, loss of connexin mediated cell-cell communication within the nephron may represent an early sign of disease; however, our current knowledge of the role of connexins in the diabetic kidney is sparse. This review highlights recent evidence demonstrating that maintenance of connexin-mediated cell-cell communication could benefit region-specific renal function in diabetic nephropathy and suggests that these proteins should be viewed as a tantalising novel target for therapeutic intervention.
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Affiliation(s)
- Claire E Hills
- School of Life Sciences, University of Lincoln, Brayford Pool, Lincoln, LN6 7TS, UK,
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Mironova E, Boiko N, Bugaj V, Kucher V, Stockand JD. Regulation of Na+ excretion and arterial blood pressure by purinergic signalling intrinsic to the distal nephron: consequences and mechanisms. Acta Physiol (Oxf) 2015; 213:213-21. [PMID: 25154328 DOI: 10.1111/apha.12372] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Revised: 08/14/2014] [Accepted: 08/21/2014] [Indexed: 12/13/2022]
Abstract
Discretionary control of Na(+) excretion is a key component of the regulation of arterial blood pressure in mammals. Sodium excretion is fine-tuned in the aldosterone-sensitive distal nephron by the activity of the epithelial Na(+) channel (ENaC). Here, ENaC functions as a final effector of the renin-angiotensin-aldosterone system (RAAS) during negative feedback control of blood pressure. Mutations affecting ENaC activity and abnormal regulation of this channel affect blood pressure through pathological changes to Na(+) excretion. Recent evidence demonstrates that powerful signalling pathways function in parallel with the RAAS to modulate ENaC activity and blood pressure. An inclusive paradigm is emerging with respect to regulation of blood pressure where ENaC serves as a critical point of convergence for several important signalling systems that affect renal Na(+) excretion. A robust inhibitory purinergic signalling system intrinsic to the distal nephron dynamically regulates ENaC through paracrine ATP signalling via the metabotropic P2Y2 purinergic receptor to properly match urinary Na(+) excretion to dietary Na(+) intake. This enables blood pressure to be maintained within a normal range despite broad changes in dietary Na(+) consumption. Loss of purinergic inhibition of ENaC increases blood pressure by causing inappropriate Na(+) excretion. In contrast, stimulation of the P2Y2 receptor promotes natriuresis and a decrease in blood pressure. Such observations identify purinergic signalling in the distal nephron as possibly causative, when dysfunctional, for certain forms of elevated blood pressure, and as a possible therapeutic target for the treatment of elevated blood pressure particularly that associated with salt sensitivity.
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Affiliation(s)
- E. Mironova
- Department of Physiology; University of Texas Health Science Center; San Antonio TX USA
| | - N. Boiko
- Department of Physiology; University of Texas Health Science Center; San Antonio TX USA
| | - V. Bugaj
- Department of Physiology; University of Texas Health Science Center; San Antonio TX USA
| | - V. Kucher
- Department of Physiology; University of Texas Health Science Center; San Antonio TX USA
| | - J. D. Stockand
- Department of Physiology; University of Texas Health Science Center; San Antonio TX USA
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Montero TD, Orellana JA. Hemichannels: new pathways for gliotransmitter release. Neuroscience 2014; 286:45-59. [PMID: 25475761 DOI: 10.1016/j.neuroscience.2014.11.048] [Citation(s) in RCA: 76] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2014] [Revised: 10/14/2014] [Accepted: 11/20/2014] [Indexed: 01/16/2023]
Abstract
Growing evidence suggests that glial cells express virtually all known types of neurotransmitter receptors, enabling them to sense neuronal activity and microenvironment changes by responding locally via the Ca(2+)-dependent release of bioactive molecules, known as "gliotransmitters". Several mechanisms of gliotransmitter release have been documented. One of these mechanisms involves the opening of plasma membrane channels, known as hemichannels. These channels are composed of six protein subunits consisting of connexins or pannexins, two highly conserved protein families encoded by 21 or 3 genes, respectively, in humans. Most data indicate that under physiological conditions, glial cell hemichannels have low activity, but this activity is sufficient to ensure the release of relevant quantities of gliotransmitters to the extracellular milieu, including ATP, glutamate, adenosine and glutathione. Nevertheless, it has been suggested that dysregulations of hemichannel properties could be critical in the beginning and during the maintenance of homeostatic imbalances observed in several brain diseases. In this study, we review the current knowledge on the hemichannel-dependent release of gliotransmitters in the physiology and pathophysiology of the CNS.
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Affiliation(s)
- T D Montero
- Departamento de Neurología, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - J A Orellana
- Departamento de Neurología, Escuela de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile.
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Solini A, Usuelli V, Fiorina P. The dark side of extracellular ATP in kidney diseases. J Am Soc Nephrol 2014; 26:1007-16. [PMID: 25452669 DOI: 10.1681/asn.2014070721] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Intracellular ATP is the most vital source of cellular energy for biologic systems, whereas extracellular ATP is a multifaceted mediator of several cell functions via its interaction, in an autocrine or paracrine manner, with P2 purinergic receptors expressed on the cell surface. These ionotropic and metabotropic P2 purinergic receptors modulate a variety of physiologic events upon the maintenance of a highly sensitive "set point," the derangement of which may lead to the development of key pathogenic mechanisms during acute and chronic diseases. Growing evidence suggests that extracellular ATP signaling via P2 purinergic receptors may be involved in different renal pathologic conditions. For these reasons, investigators and pharmaceutical companies are actively exploring novel strategies to antagonize or block these receptors with the goal of reducing extracellular ATP production or accelerating extracellular ATP clearance. Targeting extracellular ATP signaling, particularly through the P2X7 receptor, has considerable translational potential, given that novel P2X7-receptor inhibitors are already available for clinical use (e.g., CE224,535, AZD9056, and GSK1482160). This review summarizes the current evidence regarding the involvement of extracellular ATP and its P2 purinergic receptor-mediated signaling in physiologic and pathologic processes in the kidney; potential therapeutic options targeting extracellular ATP purinergic receptors are analyzed as well.
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Affiliation(s)
- Anna Solini
- Department of Clinical and Experimental Medicine, University of Pisa, Pisa, Italy
| | - Vera Usuelli
- Division of Transplant Medicine, San Raffaele Hospital, Milan, Italy; and
| | - Paolo Fiorina
- Division of Transplant Medicine, San Raffaele Hospital, Milan, Italy; and Nephrology Division, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
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Carrisoza-Gaytan R, Liu Y, Flores D, Else C, Lee HG, Rhodes G, Sandoval RM, Kleyman TR, Lee FYI, Molitoris B, Satlin LM, Rohatgi R. Effects of biomechanical forces on signaling in the cortical collecting duct (CCD). Am J Physiol Renal Physiol 2014; 307:F195-204. [PMID: 24872319 DOI: 10.1152/ajprenal.00634.2013] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
An increase in tubular fluid flow rate (TFF) stimulates Na reabsorption and K secretion in the cortical collecting duct (CCD) and subjects cells therein to biomechanical forces including fluid shear stress (FSS) and circumferential stretch (CS). Intracellular MAPK and extracellular autocrine/paracrine PGE2 signaling regulate cation transport in the CCD and, at least in other systems, are affected by biomechanical forces. We hypothesized that FSS and CS differentially affect MAPK signaling and PGE2 release to modulate cation transport in the CCD. To validate that CS is a physiological force in vivo, we applied the intravital microscopic approach to rodent kidneys in vivo to show that saline or furosemide injection led to a 46.5 ± 2.0 or 170 ± 32% increase, respectively, in distal tubular diameter. Next, murine CCD (mpkCCD) cells were grown on glass or silicone coated with collagen type IV and subjected to 0 or 0.4 dyne/cm(2) of FSS or 10% CS, respectively, forces chosen based on prior biomechanical modeling of ex vivo microperfused CCDs. Cells exposed to FSS expressed an approximately twofold greater abundance of phospho(p)-ERK and p-p38 vs. static cells, while CS did not alter p-p38 and p-ERK expression compared with unstretched controls. FSS induced whereas CS reduced PGE2 release by ∼40%. In conclusion, FSS and CS differentially affect ERK and p38 activation and PGE2 release in a cell culture model of the CD. We speculate that TFF differentially regulates biomechanical signaling and, in turn, cation transport in the CCD.
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Affiliation(s)
| | - Yu Liu
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Daniel Flores
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Medicine, James J. Peters Veterans Affairs Medical Center, New York, New York
| | - Cindy Else
- Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Heon Goo Lee
- Department of Orthopedics, Robert Carroll and Jane Chace Carroll Laboratories, Columbia College of Physicians and Surgeons, New York, New York
| | - George Rhodes
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana; and
| | - Ruben M Sandoval
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana; and
| | - Thomas R Kleyman
- Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Francis Young-In Lee
- Department of Orthopedics, Robert Carroll and Jane Chace Carroll Laboratories, Columbia College of Physicians and Surgeons, New York, New York
| | - Bruce Molitoris
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana; and
| | - Lisa M Satlin
- Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Rajeev Rohatgi
- Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Medicine, James J. Peters Veterans Affairs Medical Center, New York, New York;
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Peti-Peterdi J, Burford JL, Hackl MJ. Can kidney regeneration be visualized? Nephron Clin Pract 2014; 126:86. [PMID: 24854647 DOI: 10.1159/000360673] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Various cell types, including podocytes and parietal epithelial cells, play important roles in the development and progression of glomerular kidney diseases, albuminuria, and glomerulosclerosis. Besides their role in renal pathologies, glomerular cells have emerging new functions in endogenous repair mechanisms. A better understanding of the dynamics of the glomerular environment and cellular composition in an intact living kidney is critically important for the development of new regenerative therapeutic strategies for kidney diseases. However, progress in this field has been hampered by the lack of in vivo research tools. SUMMARY This review summarizes the current state-of-the-art in the application of the unique intravital imaging technology of multiphoton fluorescence microscopy for the dynamic visualization of glomerular structure and function over time in the intact, living kidney. Recently, this imaging approach in combination with transgenic mouse models allowed tracking of the fate of individual glomerular cells in vivo over several days and depicted the highly dynamic nature of the glomerular environment, particularly in disease conditions. KEY MESSAGES The technology is ready and available for future intravital imaging studies investigating new glomerular regenerative approaches in animal models.
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Affiliation(s)
- János Peti-Peterdi
- Department of Physiology and Biophysics, Zilkha Neurogenetic Institute, University of Southern California, Los Angeles, Calif., USA
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