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Lambert C, Schmidt K, Karger M, Stadler M, Stradal TEB, Rottner K. Cytochalasans and Their Impact on Actin Filament Remodeling. Biomolecules 2023; 13:1247. [PMID: 37627312 PMCID: PMC10452583 DOI: 10.3390/biom13081247] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2023] [Revised: 07/28/2023] [Accepted: 08/06/2023] [Indexed: 08/27/2023] Open
Abstract
The eukaryotic actin cytoskeleton comprises the protein itself in its monomeric and filamentous forms, G- and F-actin, as well as multiple interaction partners (actin-binding proteins, ABPs). This gives rise to a temporally and spatially controlled, dynamic network, eliciting a plethora of motility-associated processes. To interfere with the complex inter- and intracellular interactions the actin cytoskeleton confers, small molecular inhibitors have been used, foremost of all to study the relevance of actin filaments and their turnover for various cellular processes. The most prominent inhibitors act by, e.g., sequestering monomers or by interfering with the polymerization of new filaments and the elongation of existing filaments. Among these inhibitors used as tool compounds are the cytochalasans, fungal secondary metabolites known for decades and exploited for their F-actin polymerization inhibitory capabilities. In spite of their application as tool compounds for decades, comprehensive data are lacking that explain (i) how the structural deviances of the more than 400 cytochalasans described to date influence their bioactivity mechanistically and (ii) how the intricate network of ABPs reacts (or adapts) to cytochalasan binding. This review thus aims to summarize the information available concerning the structural features of cytochalasans and their influence on the described activities on cell morphology and actin cytoskeleton organization in eukaryotic cells.
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Affiliation(s)
- Christopher Lambert
- Molecular Cell Biology Group, Helmholtz Centre for Infection Research (HZI), Inhoffenstrasse 7, 38124 Braunschweig, Germany
- Department of Cell Biology, Helmholtz Centre for Infection Research (HZI), Inhoffenstrasse 7, 38124 Braunschweig, Germany
- Department of Microbial Drugs, Helmholtz Centre for Infection Research and German Centre for Infection Research (DZIF), Partner Site Hannover/Braunschweig, Inhoffenstrasse 7, 38124 Braunschweig, Germany;
| | - Katharina Schmidt
- Department of Cell Biology, Helmholtz Centre for Infection Research (HZI), Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Marius Karger
- Molecular Cell Biology Group, Helmholtz Centre for Infection Research (HZI), Inhoffenstrasse 7, 38124 Braunschweig, Germany
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany
| | - Marc Stadler
- Department of Microbial Drugs, Helmholtz Centre for Infection Research and German Centre for Infection Research (DZIF), Partner Site Hannover/Braunschweig, Inhoffenstrasse 7, 38124 Braunschweig, Germany;
| | - Theresia E. B. Stradal
- Department of Cell Biology, Helmholtz Centre for Infection Research (HZI), Inhoffenstrasse 7, 38124 Braunschweig, Germany
| | - Klemens Rottner
- Molecular Cell Biology Group, Helmholtz Centre for Infection Research (HZI), Inhoffenstrasse 7, 38124 Braunschweig, Germany
- Department of Cell Biology, Helmholtz Centre for Infection Research (HZI), Inhoffenstrasse 7, 38124 Braunschweig, Germany
- Division of Molecular Cell Biology, Zoological Institute, Technische Universität Braunschweig, Spielmannstrasse 7, 38106 Braunschweig, Germany
- Braunschweig Integrated Centre of Systems Biology (BRICS), 38106 Braunschweig, Germany
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2
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Kawakibi T, Bala N, Liu LP, Searcy LA, Denslow ND, Alli AA. Decreased MARCKS Protein Expression in Kidney Cortex Membrane Fractions of Cathepsin B Knockout Mice Is Associated with Reduced Lysophosphatidylcholine and Protein Kinase C Activity. Biomedicines 2023; 11:1489. [PMID: 37239160 PMCID: PMC10216610 DOI: 10.3390/biomedicines11051489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 04/28/2023] [Accepted: 05/12/2023] [Indexed: 05/28/2023] Open
Abstract
Cathpesin B is a multi-functional protease that plays numerous roles in physiology and pathophysiology. We hypothesized that actin cytoskeleton proteins that are substrates of cathepsin B, various lipids, and kinases that are regulated by lipids would be down-regulated in the kidney of cathepsin B knockout mice. Here, we show by Western blot and densitometric analysis that the expression and proteolysis of the actin cytoskeleton proteins myristoylated alanine-rich C-kinase substrate (MARCKS) and spectrin are significantly reduced in kidney cortex membrane fractions of cathepsin B knockout mice compared to C57B6 wild-type control mice. Lipidomic results show that specific lipids are increased while other lipids, including lysophosphatidylcholine (LPC) species LPC (16:0), LPC (18:0), LPC (18:1), and LPC (18:2), are significantly decreased in membrane fractions of the kidney cortex from Cathepsin B null mice. Protein Kinase C (PKC) activity is significantly lower in the kidney cortex of cathepsin B knockout mice compared to wild-type mice, while calcium/calmodulin-dependent protein kinase II (CaMKII) activity and phospholipase D (PLD) activity are comparable between the two groups. Together, these results provide the first evidence of altered actin cytoskeleton organization, membrane lipid composition, and PKC activity in the kidneys of mice lacking cathepsin B.
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Affiliation(s)
- Tamim Kawakibi
- Department of Physiology and Aging, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Niharika Bala
- Department of Physiology and Aging, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Lauren P. Liu
- Department of Physiology and Aging, University of Florida College of Medicine, Gainesville, FL 32610, USA
| | - Louis A. Searcy
- Department of Physiological Sciences and Center for Environmental and Human Toxicology, University of Florida College of Veterinary Medicine, Gainesville, FL 32610, USA
| | - Nancy D. Denslow
- Department of Physiological Sciences and Center for Environmental and Human Toxicology, University of Florida College of Veterinary Medicine, Gainesville, FL 32610, USA
| | - Abdel A. Alli
- Department of Physiology and Aging, University of Florida College of Medicine, Gainesville, FL 32610, USA
- Department of Medicine, Division of Nephrology, Hypertension, and Renal Transplantation, University of Florida College of Medicine, Gainesville, FL 32610, USA
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3
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Bala N, Yu L, Liu LP, Shelton L, Xu Y, Ghayee HK, Alli AA. Metabolic Characterization and Glyceraldehyde-3-Phosphate Dehydrogenase-Dependent Regulation of Epithelial Sodium Channels in hPheo1 Wild-type and SDHB Knockdown Cells. Endocrinology 2023; 164:7034155. [PMID: 36763043 DOI: 10.1210/endocr/bqad026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 01/26/2023] [Accepted: 01/30/2023] [Indexed: 02/11/2023]
Abstract
Pheochromocytomas (PCC) and paragangliomas (PGL) are rare neuroendocrine tumors with limited curative treatment options outside of surgical resection. Patients with mutations in succinate dehydrogenase subunit B (SDHB) are at an increased risk of malignant and aggressive disease. As cation channels are associated with tumorigenesis, we studied the expression and activity of cation channels from the Degenerin superfamily in a progenitor cell line derived from a human PCC. hPheo1 wild-type (WT) and SDHB knockdown (KD) cells were studied to investigate whether epithelial sodium channels (ENaC) and acid-sensing ion channels (ASIC) are regulated by the activity of glyceraldehyde-3-phosphate dehydrogenase (GAPDH). First, we performed targeted metabolomic studies and quantified changes in glycolysis pathway intermediates and citric acid cycle intermediates using hPheo1 WT cells and SDHB KD cells. Next, we performed protein biochemistry and electrophysiology studies to characterize the protein expression and activity, respectively, of these ion channels. Our western blot experiments show both ENaC alpha and ASIC1/2 are expressed in both hPheo1 WT and SDHB KD cells, with lower levels of a cleaved 60 kDa form of ENaC in SDHB KD cells. Single-channel patch clamp studies corroborate these results and further indicate channel activity is decreased in SDHB KD cells. Additional experiments showed a more significant decreased membrane potential in SDHB KD cells, which were sensitive to amiloride compared to WT cells. We provide evidence for the differential expression and activity of ENaC and ASIC hybrid channels in hPheo1 WT and SDHB KD cells, providing an important area of investigation in understanding SDHB-related disease.
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Affiliation(s)
- Niharika Bala
- Department of Physiology and Aging, University of Florida College of Medicine, Gainesville, FL, USA
| | - Ling Yu
- Department of Physiology and Aging, University of Florida College of Medicine, Gainesville, FL, USA
| | - Lauren P Liu
- Department of Physiology and Aging, University of Florida College of Medicine, Gainesville, FL, USA
| | | | - Yiling Xu
- Department of Medicine, Division of Endocrinology & Metabolism, University of Florida College of Medicine, Gainesville, FL, USA
| | - Hans K Ghayee
- Department of Medicine, Division of Endocrinology & Metabolism, University of Florida College of Medicine, Gainesville, FL, USA
- Malcom Randall VA Medical Center, Gainesville, FL, USA
| | - Abdel A Alli
- Department of Physiology and Aging, University of Florida College of Medicine, Gainesville, FL, USA
- Department of Medicine Division of Nephrology, Hypertension, and Renal Transplantation, University of Florida College of Medicine, Gainesville, FL, USA
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4
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Kaulich E, Grundy LJ, Schafer WR, Walker DS. The diverse functions of the DEG/ENaC family: linking genetic and physiological insights. J Physiol 2022; 601:1521-1542. [PMID: 36314992 PMCID: PMC10148893 DOI: 10.1113/jp283335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 10/25/2022] [Indexed: 11/06/2022] Open
Abstract
The DEG/ENaC family of ion channels was defined based on the sequence similarity between degenerins (DEG) from the nematode Caenorhabditis elegans and subunits of the mammalian epithelial sodium channel (ENaC), and also includes a diverse array of non-voltage-gated cation channels from across animal phyla, including the mammalian acid-sensing ion channels (ASICs) and Drosophila pickpockets. ENaCs and ASICs have wide ranging medical importance; for example, ENaCs play an important role in respiratory and renal function, and ASICs in ischaemia and inflammatory pain, as well as being implicated in memory and learning. Electrophysiological approaches, both in vitro and in vivo, have played an essential role in establishing the physiological properties of this diverse family, identifying an array of modulators and implicating them in an extensive range of cellular functions, including mechanosensation, acid sensation and synaptic modulation. Likewise, genetic studies in both invertebrates and vertebrates have played an important role in linking our understanding of channel properties to function at the cellular and whole animal/behavioural level. Drawing together genetic and physiological evidence is essential to furthering our understanding of the precise cellular roles of DEG/ENaC channels, with the diversity among family members allowing comparative physiological studies to dissect the molecular basis of these diverse functions.
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Affiliation(s)
- Eva Kaulich
- Neurobiology Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, UK
| | - Laura J Grundy
- Neurobiology Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, UK
| | - William R Schafer
- Neurobiology Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, UK.,Department of Biology, KU Leuven, Leuven, Belgium
| | - Denise S Walker
- Neurobiology Division, MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, UK
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The Pharmacological Inhibition of CaMKII Regulates Sodium Chloride Cotransporter Activity in mDCT15 Cells. BIOLOGY 2021; 10:biology10121335. [PMID: 34943250 PMCID: PMC8698651 DOI: 10.3390/biology10121335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 11/23/2021] [Accepted: 12/08/2021] [Indexed: 11/17/2022]
Abstract
The thiazide-sensitive sodium chloride cotransporter (NCC) in the distal convoluted tubule is responsible for reabsorbing up to one-tenth of the total filtered load of sodium in the kidney. The actin cytoskeleton is thought to regulate various transport proteins in the kidney but the regulation of the NCC by the actin cytoskeleton is largely unknown. Here, we identify a direct interaction between the NCC and the cytoskeletal protein filamin A in mouse distal convoluted tubule (mDCT15) cells and in the native kidney. We show that the disruption of the actin cytoskeleton by two different mechanisms downregulates NCC activity. As filamin A is a substrate of the Ca2+/calmodulin-dependent protein kinase II (CaMKII), we investigate the physiological significance of CaMKII inhibition on NCC luminal membrane protein expression and NCC activity in mDCT15 cells. The pharmacological inhibition of CaMKII with the compound KN93 increases the active form of the NCC (phospho-NCC) at the luminal membrane and also increases NCC activity in mDCT15 cells. These data suggest that the interaction between the NCC and filamin A is dependent on CaMKII activity, which may serve as a feedback mechanism to maintain basal levels of NCC activity in the distal nephron.
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Xu BY, Jin Y, Ma XH, Wang CY, Guo Y, Zhou D. The potential role of mechanically sensitive ion channels in the physiology, injury, and repair of articular cartilage. J Orthop Surg (Hong Kong) 2021; 28:2309499020950262. [PMID: 32840428 DOI: 10.1177/2309499020950262] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Biomechanical factors play an extremely important role in regulating the function of articular chondrocytes. Understanding the mechanical factors that drive chondrocyte biological responses is at the heart of our interpretation of cascade events leading to changes in articular cartilage osteoarthritis. The mechanism by which mechanical load is transduced into intracellular signals that can regulate chondrocyte gene expression remains largely unknown. The mechanically sensitive ion channel (MSC) may be one of its specific mechanisms. This review focuses on four ion channels involved in the mechanotransduction of chondrocytes, exploring their properties and the main factors that activate the associated pathways. The upstream and downstream potential relationships between the protein pathways were also explored. The specific biophysical mechanism of the chondrocyte mechanical microenvironment is becoming the focus of research. Elucidating the mechanotransduction mechanism of MSC is essential for the research of biophysical pathogenesis and targeted drugs in cartilage injury-related diseases.
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Affiliation(s)
- Bo-Yang Xu
- School of Acupuncture-Moxibustion and Tuina, 58301Tianjin University of Traditional Chinese Medicine, Tianjin, People's Republic of China
| | - Yu Jin
- School of Chinese Medicine, 58301Tianjin University of Traditional Chinese Medicine, Tianjin, People's Republic of China
| | - Xiao-Hui Ma
- School of Culture and Health Communication, 58301Tianjin University of Traditional Chinese Medicine, Tianjin, People's Republic of China
| | - Chi-Yu Wang
- Department of Electrical Engineering and Computer Sciences, 1438University of California, Berkeley, CA, USA
| | - Yi Guo
- School of Chinese Medicine, 58301Tianjin University of Traditional Chinese Medicine, Tianjin, People's Republic of China.,Research Center of Experimental Acupuncture Science, 58301Tianjin University of Traditional Chinese Medicine, Tianjin, People's Republic of China.,National Clinical Research Center for Chinese Medicine Acupuncture and Moxibustion, Tianjin, People's Republic of China
| | - Dan Zhou
- School of Acupuncture-Moxibustion and Tuina, 58301Tianjin University of Traditional Chinese Medicine, Tianjin, People's Republic of China.,Research Center of Experimental Acupuncture Science, 58301Tianjin University of Traditional Chinese Medicine, Tianjin, People's Republic of China.,National Clinical Research Center for Chinese Medicine Acupuncture and Moxibustion, Tianjin, People's Republic of China
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7
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Morachevskaya EA, Sudarikova AV. Actin dynamics as critical ion channel regulator: ENaC and Piezo in focus. Am J Physiol Cell Physiol 2021; 320:C696-C702. [PMID: 33471624 DOI: 10.1152/ajpcell.00368.2020] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Ion channels in plasma membrane play a principal role in different physiological processes, including cell volume regulation, signal transduction, and modulation of membrane potential in living cells. Actin-based cytoskeleton, which exists in a dynamic balance between monomeric and polymeric forms (globular and fibrillar actin), can be directly or indirectly involved in various cellular responses including modulation of ion channel activity. In this mini-review, we present an overview of the role of submembranous actin dynamics in the regulation of ion channels in excitable and nonexcitable cells. Special attention is focused on the important data about the involvement of actin assembly/disassembly and some actin-binding proteins in the control of the epithelial Na+ channel (ENaC) and mechanosensitive Piezo channels whose integral activity has a potential impact on membrane transport and multiple coupled cellular reactions. Growing evidence suggests that actin elements of the cytoskeleton can represent a "converging point" of various signaling pathways modulating the activity of ion transport proteins in cell membranes.
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Tuna KM, Liu BC, Yue Q, Ghazi ZM, Ma HP, Eaton DC, Alli AA. Mal protein stabilizes luminal membrane PLC-β3 and negatively regulates ENaC in mouse cortical collecting duct cells. Am J Physiol Renal Physiol 2019; 317:F986-F995. [PMID: 31364376 PMCID: PMC6843038 DOI: 10.1152/ajprenal.00446.2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 07/18/2019] [Accepted: 07/18/2019] [Indexed: 01/15/2023] Open
Abstract
Abnormally high epithelial Na+ channel (ENaC) activity in the aldosterone-sensitive distal nephron and collecting duct leads to hypertension. Myelin and lymphocyte (Mal) is a lipid raft-associated protein that has been previously shown to regulate Na+-K-2Cl- cotransporter and aquaporin-2 in the kidney, but it is not known whether it regulates renal ENaC. ENaC activity is positively regulated by the anionic phospholipid phosphate phosphatidylinositol 4,5-bisphosphate (PIP2). Members of the myristoylated alanine-rich C-kinase substrate (MARCKS) family increase PIP2 concentrations at the plasma membrane, whereas hydrolysis of PIP2 by phospholipase C (PLC) reduces PIP2 abundance. Our hypothesis was that Mal protein negatively regulates renal ENaC activity by stabilizing PLC protein expression at the luminal plasma membrane. We investigated the association between Mal, MARCKS-like protein, and ENaC. We showed Mal colocalizes with PLC-β3 in lipid rafts and positively regulates its protein expression, thereby reducing PIP2 availability at the plasma membrane. Kidneys of 129Sv mice injected with MAL shRNA lentivirus resulted in increased ENaC open probability in split-open renal tubules. Overexpression of Mal protein in mouse cortical collecting duct (mpkCCD) cells resulted in an increase in PLC-β3 protein expression at the plasma membrane. siRNA-mediated knockdown of MAL in mpkCCD cells resulted in a decrease in PLC-β3 protein expression and an increase in PIP2 abundance. Moreover, kidneys from salt-loaded mice showed less Mal membrane protein expression compared with non-salt-loaded mice. Taken together, Mal protein may play an essential role in the negative feedback of ENaC gating in principal cells of the collecting duct.
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Affiliation(s)
- Kubra M Tuna
- Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida
| | - Bing-Chen Liu
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - Qiang Yue
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - Zinah M Ghazi
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - He-Ping Ma
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - Douglas C Eaton
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - Abdel A Alli
- Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida
- Department of Medicine, Division of Nephrology, Hypertension, and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
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Alli A, Yu L, Holzworth M, Richards J, Cheng KY, Lynch IJ, Wingo CS, Gumz ML. Direct and indirect inhibition of the circadian clock protein Per1: effects on ENaC and blood pressure. Am J Physiol Renal Physiol 2019; 316:F807-F813. [PMID: 30759025 DOI: 10.1152/ajprenal.00408.2018] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Circadian rhythms govern physiological functions and are important for overall health. The molecular circadian clock comprises several transcription factors that mediate circadian control of physiological function, in part, by regulating gene expression in a tissue-specific manner. These connections are well established, but the underlying mechanisms are incompletely understood. The overall goal of this study was to examine the connection among the circadian clock protein Period 1 (Per1), epithelial Na+ channel (ENaC), and blood pressure (BP) using a multipronged approach. Using global Per1 knockout mice on a 129/sv background in combination with a high-salt diet plus mineralocorticoid treatment, we demonstrated that loss of Per1 in this setting is associated with protection from hypertension. Next, we used the ENaC inhibitor benzamil to demonstrate a role for ENaC in BP regulation and urinary Na+ excretion in 129/sv mice. We targeted Per1 indirectly using pharmacological inhibition of Per1 nuclear entry in vivo to demonstrate altered expression of known Per1 target genes as well as a BP-lowering effect in 129/sv mice. Finally, we directly inhibited Per1 via genetic knockdown in amphibian distal nephron cells to demonstrate, for the first time, that reduced Per1 expression is associated with decreased ENaC activity at the single channel level.
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Affiliation(s)
- Abdel Alli
- Department of Physiology and Functional Genomics, University of Florida , Gainesville, Florida.,Division of Nephrology, Hypertension, and Renal Transplantation, Department of Medicine, University of Florida , Gainesville, Florida
| | - Ling Yu
- Department of Physiology and Functional Genomics, University of Florida , Gainesville, Florida.,College of Resources and Environmental Sciences, Nanjing Agricultural University , Nanjing , China
| | - Meaghan Holzworth
- Division of Nephrology, Hypertension, and Renal Transplantation, Department of Medicine, University of Florida , Gainesville, Florida
| | - Jacob Richards
- Division of Nephrology, Hypertension, and Renal Transplantation, Department of Medicine, University of Florida , Gainesville, Florida
| | - Kit-Yan Cheng
- Division of Nephrology, Hypertension, and Renal Transplantation, Department of Medicine, University of Florida , Gainesville, Florida.,North Florida/South Georgia Veterans Affairs Medical Center , Gainesville, Florida
| | - I Jeanette Lynch
- Division of Nephrology, Hypertension, and Renal Transplantation, Department of Medicine, University of Florida , Gainesville, Florida.,North Florida/South Georgia Veterans Affairs Medical Center , Gainesville, Florida
| | - Charles S Wingo
- Department of Physiology and Functional Genomics, University of Florida , Gainesville, Florida.,Division of Nephrology, Hypertension, and Renal Transplantation, Department of Medicine, University of Florida , Gainesville, Florida.,North Florida/South Georgia Veterans Affairs Medical Center , Gainesville, Florida
| | - Michelle L Gumz
- Division of Nephrology, Hypertension, and Renal Transplantation, Department of Medicine, University of Florida , Gainesville, Florida.,North Florida/South Georgia Veterans Affairs Medical Center , Gainesville, Florida.,Department of Biochemistry and Molecular Biology, University of Florida , Gainesville, Florida
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Mendes G, Baltazar LM, Souza DG, Sá NP, Rosa LH, Rosa CA, Souza-Fagundes EM, Ramos JP, Alves-Silva J, Cota BB, Johann S. Effects of cytochalasin E on Paracoccidioides brasiliensis. J Appl Microbiol 2018; 125:1296-1307. [PMID: 30053334 DOI: 10.1111/jam.14053] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 05/28/2018] [Accepted: 07/13/2018] [Indexed: 02/03/2023]
Abstract
AIMS To determine the effects of cytochalasin E, isolated from the extremophile fungus Aspergillus felis, on the cells of Paracoccidioides brasiliensis Pb18. METHODS AND RESULTS Cytochalasin E showed a minimal inhibitory concentration of 3·6 μmol l-1 and minimum fungicidal concentration of 7·2 μmol l-1 on P. brasiliensis by in vitro microdilution and IC50 >964·0 μmol l-1 on murine macrophages. Its selectivity index (>263) indicated that this compound has selectivity for fungal cells. Morphological alterations were determined by optical and fluorescence microscopy, as well as scanning and transmission electron microscopy. Cytochalasin E affected P. brasiliensis bud-forming pseudohyphae, cell morphology, cell walls and cell membranes; caused the release of cellular material; and resulted in the production of reactive oxygen species. In murine macrophages, it affected cytoskeletal actin and inhibited phagocytosis. CONCLUSION Cytochalasin E may be useful as an antifungal prototype against P. brasiliensis and in studies on phagocytosis. SIGNIFICANCE AND IMPACT OF THE STUDY Paracoccidioides spp. are the etiological agents of paracoccidioidomycosis (PCM). Treatment is prolonged to control the clinical manifestations and prevent relapse. The study on the effects of cytochalasin E in P. brasiliensis is important because it can be used as a prototype for new antifungal drugs and consequently, broadens the treatment options for PCM.
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Affiliation(s)
- G Mendes
- Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil.,Laboratório de Química de Produtos Naturais Bioativos, Instituto René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Brazil
| | - L M Baltazar
- Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - D G Souza
- Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - N P Sá
- Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - L H Rosa
- Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - C A Rosa
- Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - E M Souza-Fagundes
- Departamento de Fisiologia e Biofísica, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - J P Ramos
- Departamento de Fisiologia e Biofísica, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - J Alves-Silva
- Departamento de Morfologia da Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - B B Cota
- Laboratório de Química de Produtos Naturais Bioativos, Instituto René Rachou, Fundação Oswaldo Cruz, Belo Horizonte, Brazil
| | - S Johann
- Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
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11
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Dang VD, Jella KK, Ragheb RRT, Denslow ND, Alli AA. Lipidomic and proteomic analysis of exosomes from mouse cortical collecting duct cells. FASEB J 2017; 31:5399-5408. [PMID: 28821634 DOI: 10.1096/fj.201700417r] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2017] [Accepted: 07/25/2017] [Indexed: 12/13/2022]
Abstract
Exosomes are endosome-derived nanovesicles that are involved in cellular communication and signaling. Exosomes are produced by epithelial cells and are found in biologic fluids including blood and urine. The packaged material within exosomes includes proteins and lipids, but the molecular comparison within exosome subtypes is largely unknown. The purpose of this study was to investigate differences between exosomes derived from the apical plasma membrane and basolateral plasma membrane of polarized murine cortical collecting duct principal cells. Nanoparticle tracking analysis showed that the size and concentration of apical and basolateral exosomes remained relatively stable across 3 different temperatures (23, 37, and 42°C). Liquid chromatography-tandem mass spectrometry analysis revealed marked differences between the proteins packaged within the two types of exosomes from the same cells. Several proteins expressed at the inner leaflet of the plasma membrane, including α-actinin-1, moesin, 14-3-3 protein ζ/δ, annexin A1/A3/A4/A5/A6, clathrin heavy chain 1, glyceraldehyde-3-phosphate dehydrogenase, α-enolase, filamin-A, and heat shock protein 90, were identified in samples of apical plasma membrane-derived exosomes, but not in basolateral plasma membrane exosomes from mouse cortical collecting duct cells. In addition to differences at the protein level, mass spectrometry-based shotgun lipidomics analysis showed significant differences in the lipid classes and fatty acid composition of the two types of exosomes. We found higher levels of sphingomyelin and lower levels of cardiolipin, among other phospholipids in the apical plasma membrane compared to the basolateral plasma membrane exosomes. The molecular analyses of exosome subtypes presented herein will contribute to our understanding of exosome biogenesis, and the results may have potential implications for biomarker discovery.-Dang, V. D., Jella, K. K., Ragheb, R. R. T., Denslow, N. D., Alli, A. A. Lipidomic and proteomic analysis of exosomes from mouse cortical collecting duct cells.
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Affiliation(s)
- Viet D Dang
- Department of Physiological Sciences, University of Florida, Gainesville, Florida, USA.,Center for Environmental and Human Toxicology, University of Florida, Gainesville, Florida, USA.,Department of Veterinary Diagnostic and Production Animal Production, Iowa State University, Ames, Iowa, USA
| | - Kishore Kumar Jella
- Department of Radiation Oncology, Emory University School of Medicine, Atlanta, Georgia, USA
| | | | - Nancy D Denslow
- Department of Physiological Sciences, University of Florida, Gainesville, Florida, USA.,Center for Environmental and Human Toxicology, University of Florida, Gainesville, Florida, USA
| | - Abdel A Alli
- Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida, USA; .,Division of Nephrology, Hypertension, and Renal Transplantation, Department of Medicine, University of Florida College of Medicine, Gainesville, Florida, USA
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12
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Czikora I, Alli AA, Sridhar S, Matthay MA, Pillich H, Hudel M, Berisha B, Gorshkov B, Romero MJ, Gonzales J, Wu G, Huo Y, Su Y, Verin AD, Fulton D, Chakraborty T, Eaton DC, Lucas R. Epithelial Sodium Channel-α Mediates the Protective Effect of the TNF-Derived TIP Peptide in Pneumolysin-Induced Endothelial Barrier Dysfunction. Front Immunol 2017; 8:842. [PMID: 28785264 PMCID: PMC5519615 DOI: 10.3389/fimmu.2017.00842] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Accepted: 07/04/2017] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Streptococcus pneumoniae is a major etiologic agent of bacterial pneumonia. Autolysis and antibiotic-mediated lysis of pneumococci induce release of the pore-forming toxin, pneumolysin (PLY), their major virulence factor, which is a prominent cause of acute lung injury. PLY inhibits alveolar liquid clearance and severely compromises alveolar-capillary barrier function, leading to permeability edema associated with pneumonia. As a consequence, alveolar flooding occurs, which can precipitate lethal hypoxemia by impairing gas exchange. The α subunit of the epithelial sodium channel (ENaC) is crucial for promoting Na+ reabsorption across Na+-transporting epithelia. However, it is not known if human lung microvascular endothelial cells (HL-MVEC) also express ENaC-α and whether this subunit is involved in the regulation of their barrier function. METHODS The presence of α, β, and γ subunits of ENaC and protein phosphorylation status in HL-MVEC were assessed in western blotting. The role of ENaC-α in monolayer resistance of HL-MVEC was examined by depletion of this subunit by specific siRNA and by employing the TNF-derived TIP peptide, a specific activator that directly binds to ENaC-α. RESULTS HL-MVEC express all three subunits of ENaC, as well as acid-sensing ion channel 1a (ASIC1a), which has the capacity to form hybrid non-selective cation channels with ENaC-α. Both TIP peptide, which specifically binds to ENaC-α, and the specific ASIC1a activator MitTx significantly strengthened barrier function in PLY-treated HL-MVEC. ENaC-α depletion significantly increased sensitivity to PLY-induced hyperpermeability and in addition, blunted the protective effect of both the TIP peptide and MitTx, indicating an important role for ENaC-α and for hybrid NSC channels in barrier function of HL-MVEC. TIP peptide blunted PLY-induced phosphorylation of both calmodulin-dependent kinase II (CaMKII) and of its substrate, the actin-binding protein filamin A (FLN-A), requiring the expression of both ENaC-α and ASIC1a. Since non-phosphorylated FLN-A promotes ENaC channel open probability and blunts stress fiber formation, modulation of this activity represents an attractive target for the protective actions of ENaC-α in both barrier function and liquid clearance. CONCLUSION Our results in cultured endothelial cells demonstrate a previously unrecognized role for ENaC-α in strengthening capillary barrier function that may apply to the human lung. Strategies aiming to activate endothelial NSC channels that contain ENaC-α should be further investigated as a novel approach to improve barrier function in the capillary endothelium during pneumonia.
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Affiliation(s)
- Istvan Czikora
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Abdel A Alli
- Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, FL, United States.,Division of Nephrology, Hypertension, and Renal Transplantation, Department of Medicine, University of Florida College of Medicine, Gainesville, FL, United States
| | - Supriya Sridhar
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Michael A Matthay
- Cardiovascular Research Institute, UCSF, San Francisco, CA, United States
| | - Helena Pillich
- Institute for Medical Microbiology, Justus-Liebig University, Giessen, Germany
| | - Martina Hudel
- Institute for Medical Microbiology, Justus-Liebig University, Giessen, Germany
| | - Besim Berisha
- Institute for Medical Microbiology, Justus-Liebig University, Giessen, Germany
| | - Boris Gorshkov
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Maritza J Romero
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA, United States.,Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Joyce Gonzales
- Department of Medicine, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Guangyu Wu
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Yuqing Huo
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA, United States.,Department of Medicine, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Yunchao Su
- Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Alexander D Verin
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA, United States.,Department of Medicine, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - David Fulton
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA, United States.,Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Trinad Chakraborty
- Institute for Medical Microbiology, Justus-Liebig University, Giessen, Germany
| | - Douglas C Eaton
- Department of Physiology, Emory University School of Medicine, Atlanta, GA, United States
| | - Rudolf Lucas
- Vascular Biology Center, Medical College of Georgia, Augusta University, Augusta, GA, United States.,Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta University, Augusta, GA, United States.,Department of Medicine, Medical College of Georgia, Augusta University, Augusta, GA, United States
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13
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Montgomery DS, Yu L, Ghazi ZM, Thai TL, Al-Khalili O, Ma HP, Eaton DC, Alli AA. ENaC activity is regulated by calpain-2 proteolysis of MARCKS proteins. Am J Physiol Cell Physiol 2017; 313:C42-C53. [PMID: 28468944 PMCID: PMC5538800 DOI: 10.1152/ajpcell.00244.2016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Revised: 04/13/2017] [Accepted: 04/15/2017] [Indexed: 12/27/2022]
Abstract
We previously demonstrated a role for the myristoylated alanine-rich C kinase substrate (MARCKS) to serve as an adaptor protein in the anionic phospholipid phosphate-dependent regulation of the epithelial sodium channel (ENaC). Both MARCKS and ENaC are regulated by proteolysis. Calpains are a family of ubiquitously expressed intracellular Ca2+-dependent cysteine proteases involved in signal transduction. Here we examine the role of calpain-2 in regulating MARCKS and ENaC in cultured renal epithelial cells and in the mouse kidney. Using recombinant fusion proteins, we show that MARCKS, but not the ENaC subunits, are a substrate of calpain-2 in the presence of Ca2+ Pharmacological inhibition of calpain-2 alters MARCKS protein expression in light-density sucrose gradient fractions from cell lysates of mouse cortical collecting duct cells. Calpain-dependent cleaved products of MARCKS are detectable in cultured renal cells. Ca2+ mobilization and calpain-2 inhibition decrease the association between ENaC and MARCKS. The inhibition of calpain-2 reduces ENaC activity as demonstrated by single-channel patch-clamp recordings and transepithelial current measurements. These results suggest that calpain-2 proteolysis of MARCKS promotes its interaction with lipids and ENaC at the plasma membrane to allow for the phosphatidylinositol 4,5-bisphosphate (PIP2)-dependent regulation of ENaC activity in the kidney.
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Affiliation(s)
- Darrice S Montgomery
- Department of Physiology and Functional Genomics and Department of Medicine Division of Nephrology, Hypertension, and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida
| | - Ling Yu
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, China; and
| | - Zinah M Ghazi
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - Tiffany L Thai
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - Otor Al-Khalili
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - He-Ping Ma
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - Douglas C Eaton
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - Abdel A Alli
- Department of Physiology and Functional Genomics and Department of Medicine Division of Nephrology, Hypertension, and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida;
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14
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Klemens CA, Edinger RS, Kightlinger L, Liu X, Butterworth MB. Ankyrin G Expression Regulates Apical Delivery of the Epithelial Sodium Channel (ENaC). J Biol Chem 2016; 292:375-385. [PMID: 27895120 DOI: 10.1074/jbc.m116.753616] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 11/11/2016] [Indexed: 11/06/2022] Open
Abstract
The epithelial sodium channel (ENaC) is the limiting entry point for Na+ reabsorption in the distal kidney nephron and is regulated by numerous hormones, including the mineralocorticoid hormone aldosterone. Previously we identified ankyrin G (AnkG), a cytoskeletal protein involved in vesicular transport, as a novel aldosterone-induced protein that can alter Na+ transport in mouse cortical collecting duct cells. However, the mechanisms underlying AnkG regulation of Na+ transport were unknown. Here we report that AnkG expression directly regulates Na+ transport by altering ENaC activity in the apical membrane. Increasing AnkG expression increased ENaC activity while depleting AnkG reduced ENaC-mediated Na+ transport. These changes were due to a change in ENaC directly rather than through alterations to the Na+ driving force created by Na+/K+-ATPase. Using a constitutively open mutant of ENaC, we demonstrate that the augmentation of Na+ transport is caused predominantly by increasing the number of ENaCs at the surface. To determine the mechanism of AnkG action on ENaC surface number, changes in rates of internalization, recycling, and membrane delivery were investigated. AnkG did not alter ENaC delivery to the membrane from biosynthetic pathways or removal by endocytosis. However, AnkG did alter ENaC insertion from constitutive recycling pathways. These findings provide a mechanism to account for the role of AnkG in the regulation of Na+ transport in the distal kidney nephron.
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Affiliation(s)
- Christine A Klemens
- From the Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - Robert S Edinger
- From the Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - Lindsay Kightlinger
- From the Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - Xiaoning Liu
- From the Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
| | - Michael B Butterworth
- From the Department of Cell Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261
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15
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Jella KK, Yu L, Yue Q, Friedman D, Duke BJ, Alli AA. Exosomal GAPDH from Proximal Tubule Cells Regulate ENaC Activity. PLoS One 2016; 11:e0165763. [PMID: 27802315 PMCID: PMC5089749 DOI: 10.1371/journal.pone.0165763] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Accepted: 10/17/2016] [Indexed: 12/19/2022] Open
Abstract
Exosomes are nanometer-scale, cell-derived vesicles that contain various molecules including nucleic acids, proteins, and lipids. These vesicles can release their cargo into adjacent or distant cells and mediate intercellular communication and cellular function. Here we examined the regulation of epithelial sodium channels in mpkCCD cells and distal tubule Xenopus 2F3 cells by exosomes isolated from proximal tubule LLC-PK1 cells. Cultured mpkCCD cells were stained with CTX coupled to a green fluorophore in order to label the cell membranes and freshly isolated exosomes from LLC-PK1 cells were labeled with the red lipophilic dye PKH26 in order to visualize uptake of exosomes into the cells. Single-channel patch clamp recordings showed the open probability of ENaC in Xenopus 2F3 cells and in freshly isolated split-open tubules decreased in response to exogenous application of exosomes derived from LLC-PK1 proximal tubule cells. Active GAPDH was identified within exosomes derived from proximal tubule LLC-PK1 cells. The effect on ENaC activity in Xenopus 2F3 cells was blunted after application of exosomes transfected with the GAPDH inhibitor heptelidic acid. Also, we show GAPDH and ENaC subunits associate in mpkCCD cells. These studies examine a potential role for exosomes in the regulation of ENaC activity and examine a possible mechanism for communication from proximal tubule cells to distal tubule and collecting duct cells.
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Affiliation(s)
- Kishore Kumar Jella
- Department of Radiation Oncology, Emory University School of Medicine, Atlanta, Georgia
| | - Ling Yu
- College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, Jiangsu Province, China
| | - Qiang Yue
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - Daniel Friedman
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - Billie J. Duke
- Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - Abdel A. Alli
- Department of Physiology and Functional Genomics and Department of Medicine Division of Nephrology, Hypertension, and Renal Transplantation, University of Florida College of Medicine, Gainesville, Florida, United States of America
- * E-mail:
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16
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Lucas R, Yue Q, Alli A, Duke BJ, Al-Khalili O, Thai TL, Hamacher J, Sridhar S, Lebedyeva I, Su H, Tzotzos S, Fischer B, Gameiro AF, Loose M, Chakraborty T, Shabbir W, Aufy M, Lemmens-Gruber R, Eaton DC, Czikora I. The Lectin-like Domain of TNF Increases ENaC Open Probability through a Novel Site at the Interface between the Second Transmembrane and C-terminal Domains of the α-Subunit. J Biol Chem 2016; 291:23440-23451. [PMID: 27645999 DOI: 10.1074/jbc.m116.718163] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Indexed: 12/29/2022] Open
Abstract
Regulation of the epithelial sodium channel (ENaC), which regulates fluid homeostasis and blood pressure, is complex and remains incompletely understood. The TIP peptide, a mimic of the lectin-like domain of TNF, activates ENaC by binding to glycosylated residues in the extracellular loop of ENaC-α, as well as to a hitherto uncharacterized internal site. Molecular docking studies suggested three residues, Val567, Glu568, and Glu571, located at the interface between the second transmembrane and C-terminal domains of ENaC-α, as a critical site for binding of the TIP peptide. We generated Ala replacement mutants in this region of ENaC-α and examined its interaction with TIP peptide (3M, V567A/E568A/E571A; 2M, V567A/E568A; and 1M, E571A). 3M and 2M ENaC-α, but not 1M ENaC-α, displayed significantly reduced binding capacity to TIP peptide and to TNF. When overexpressed in H441 cells, 3M mutant ENaC-α formed functional channels with similar gating and density characteristics as the WT subunit and efficiently associated with the β and γ subunits in the plasma membrane. We subsequently assayed for increased open probability time and membrane expression, both of which define ENaC activity, following addition of TIP peptide. TIP peptide increased open probability time in H441 cells overexpressing wild type and 1M ENaC-α channels, but not 3M or 2M ENaC-α channels. On the other hand, TIP peptide-mediated reduction in ENaC ubiquitination was similar in cells overexpressing either WT or 3M ENaC-α subunits. In summary, this study has identified a novel site in ENaC-α that is crucial for activation of the open probability of the channel, but not membrane expression, by the lectin-like domain of TNF.
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Affiliation(s)
- Rudolf Lucas
- From the Vascular Biology Center, .,the Department of Pharmacology and Toxicology, and.,the Division of Pulmonary and Critical Care Medicine, Medical College of Georgia, Augusta, Georgia 30912
| | - Qiang Yue
- the Department of Physiology, Emory University, Atlanta, Georgia 30322
| | - Abdel Alli
- the Department of Physiology, Emory University, Atlanta, Georgia 30322.,the Department of Physiology and Functional Genomics, University of Florida College of Medicine, Gainesville, Florida 32610
| | | | - Otor Al-Khalili
- the Department of Physiology, Emory University, Atlanta, Georgia 30322
| | - Tiffany L Thai
- the Department of Physiology, Emory University, Atlanta, Georgia 30322
| | - Jürg Hamacher
- the Department of Pulmonology, Saarland University, D-66421 Homburg, Germany
| | | | - Iryna Lebedyeva
- the Department of Chemistry, Augusta University, Augusta, Georgia 30912
| | - Huabo Su
- From the Vascular Biology Center
| | - Susan Tzotzos
- Apeptico Research and Development, 1150 Vienna, Austria
| | | | | | - Maria Loose
- the Institute for Medical Microbiology, Justus-Liebig University, 35390 Giessen, Germany, and
| | - Trinad Chakraborty
- the Institute for Medical Microbiology, Justus-Liebig University, 35390 Giessen, Germany, and
| | - Waheed Shabbir
- the Department of Pharmacology and Toxicology, University Vienna, 1010 Vienna, Austria
| | - Mohammed Aufy
- the Department of Pharmacology and Toxicology, University Vienna, 1010 Vienna, Austria
| | - Rosa Lemmens-Gruber
- the Department of Pharmacology and Toxicology, University Vienna, 1010 Vienna, Austria
| | - Douglas C Eaton
- the Department of Physiology, Emory University, Atlanta, Georgia 30322,
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17
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Alli AA, Bao HF, Liu BC, Yu L, Aldrugh S, Montgomery DS, Ma HP, Eaton DC. Calmodulin and CaMKII modulate ENaC activity by regulating the association of MARCKS and the cytoskeleton with the apical membrane. Am J Physiol Renal Physiol 2015; 309:F456-63. [PMID: 26136560 DOI: 10.1152/ajprenal.00631.2014] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 06/24/2015] [Indexed: 11/22/2022] Open
Abstract
Phosphatidylinositol bisphosphate (PIP2) regulates epithelial sodium channel (ENaC) open probability. In turn, myristoylated alanine-rich C kinase substrate (MARCKS) protein or MARCKS-like protein 1 (MLP-1) at the plasma membrane regulates the delivery of PIP2 to ENaC. MARCKS and MLP-1 are regulated by changes in cytosolic calcium; increasing calcium promotes dissociation of MARCKS from the membrane, but the calcium-regulatory mechanisms are unclear. However, it is known that increased intracellular calcium can activate calmodulin and we show that inhibition of calmodulin with calmidazolium increases ENaC activity presumably by regulating MARCKS and MLP-1. Activated calmodulin can regulate MARCKS and MLP-1 in two ways. Calmodulin can bind to the effector domain of MARCKS or MLP-1, inactivating both proteins by causing their dissociation from the membrane. Mutations in MARCKS that prevent calmodulin association prevent dissociation of MARCKS from the membrane. Calmodulin also activates CaM kinase II (CaMKII). An inhibitor of CaMKII (KN93) increases ENaC activity, MARCKS association with ENaC, and promotes MARCKS movement to a membrane fraction. CaMKII phosphorylates filamin. Filamin is an essential component of the cytoskeleton and promotes association of ENaC, MARCKS, and MLP-1. Disruption of the cytoskeleton with cytochalasin E reduces ENaC activity. CaMKII phosphorylation of filamin disrupts the cytoskeleton and the association of MARCKS, MLP-1, and ENaC, thereby reducing ENaC open probability. Taken together, these findings suggest calmodulin and CaMKII modulate ENaC activity by destabilizing the association between the actin cytoskeleton, ENaC, and MARCKS, or MLP-1 at the apical membrane.
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Affiliation(s)
- Abdel A Alli
- Center for Cell and Molecular Signaling, Department of Physiology, Emory University School of Medicine; Atlanta, Georgia
| | - Hui-Fang Bao
- Center for Cell and Molecular Signaling, Department of Physiology, Emory University School of Medicine; Atlanta, Georgia
| | - Bing-Chen Liu
- Center for Cell and Molecular Signaling, Department of Physiology, Emory University School of Medicine; Atlanta, Georgia
| | - Ling Yu
- Center for Cell and Molecular Signaling, Department of Physiology, Emory University School of Medicine; Atlanta, Georgia
| | - Summer Aldrugh
- Center for Cell and Molecular Signaling, Department of Physiology, Emory University School of Medicine; Atlanta, Georgia
| | - Darrice S Montgomery
- Center for Cell and Molecular Signaling, Department of Physiology, Emory University School of Medicine; Atlanta, Georgia
| | - He-Ping Ma
- Center for Cell and Molecular Signaling, Department of Physiology, Emory University School of Medicine; Atlanta, Georgia
| | - Douglas C Eaton
- Center for Cell and Molecular Signaling, Department of Physiology, Emory University School of Medicine; Atlanta, Georgia
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