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Lu B, Li L, Schneider M, Hodges CA, Cotton CU, Burgess JD, Kelley TJ. Electrochemical measurement of membrane cholesterol correlates with CFTR function and is HDAC6-dependent. J Cyst Fibros 2018; 18:175-181. [PMID: 29941319 DOI: 10.1016/j.jcf.2018.06.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 06/06/2018] [Accepted: 06/07/2018] [Indexed: 12/18/2022]
Abstract
BACKGROUND Previous studies have demonstrated that CF epithelial cells exhibit increased cholesterol content at the plasma membrane compared to wild type controls as measured by electrochemical methods. Microtubule dysregulation that impacts intracellular transport has also been identified in CF cells and is reversible with histone deacetylase 6 (HDAC6) inhibition, a regulator of tubulin acetylation. The hypothesis of this study is that increased membrane cholesterol content in CF cells is dependent on HDAC6 regulation. METHODS Electrochemical measurement of membrane cholesterol in mouse trachea and in primary human CF bronchial epithelial cells is used to monitor CFTR correction and manipulation of cholesterol processing by HDAC6 inhibition. RESULTS Data demonstrate that induction of Cftr expression in an inducible CF mouse model restores tubulin acetylation levels and normalizes membrane cholesterol content. To test the relationship between tubulin acetylation, membrane cholesterol levels were measured in a CF mouse model depleted of Hdac6 expression (CF/HDA). CF/HDA mouse trachea have WT membrane cholesterol levels while CF mice have approximately two-fold increase in membrane cholesterol compared to WT consistent with previous studies. Pharmacological inhibition of HDAC6 in primary human CF bronchial epithelial cells also reduces membrane cholesterol levels. CONCLUSIONS This study demonstrates that elevated membrane cholesterol in CF epithelium is regulated by HDAC6 function and that the electrochemical measure of membrane cholesterol correlates with both genetic and pharmacological CFTR correction.
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Affiliation(s)
- Binyu Lu
- Department of Chemistry, Case Western Reserve University, United States
| | - Li Li
- Department of Chemistry, Case Western Reserve University, United States
| | - Molly Schneider
- Department of Pediatrics, Case Western Reserve University, United States
| | - Craig A Hodges
- Department of Pediatrics, Case Western Reserve University, United States
| | - Calvin U Cotton
- Department of Pediatrics, Case Western Reserve University, United States
| | - James D Burgess
- Department of Medical, Laboratory, Imaging and Radiologic Sciences, Augusta University, United States
| | - Thomas J Kelley
- Department of Chemistry, Case Western Reserve University, United States; Department of Pediatrics, Case Western Reserve University, United States.
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2
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Zhang M, Li L, Fang D, Kelley TJ, Burgess JD. Single Cell Titration-Type Assay for Plasma Membrane Cholesterol Chemical Potential. Anal Chem 2018; 90:5903-5908. [PMID: 29658264 DOI: 10.1021/acs.analchem.8b00736] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this paper, a titration-type assay is described that determines the minimum concentration of cholesterol in solution that is required to drive net influx of cholesterol to the plasma membrane and thus increase the cholesterol concentration. The increase in cholesterol in the plasma membrane is detected by cholesterol diffusion at the site of contact by a cholesterol oxidase-modified microelectrode. In the presented thermodynamic model, the minimum solution phase cholesterol concentration that drives influx to the plasma membrane is a close approximation of the true solution-phase equilibrium concentration of cholesterol produced from cellular cholesterol efflux and as such it is a quantitative measure of the chemical potential of cholesterol in the cellular plasma membrane. This assay provides a measure of cholesterol chemical potential in the living cellular plasma membrane through reference to a solution concentration which avoids invoking classic kinetic theory to relate a rate to a specific thermodynamic activity and which avoids uncertainty associated with mass transfer phenomena.
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Affiliation(s)
- Meiling Zhang
- School of Pharmacy and Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine , Nanjing Medical University , Nanjing , Jiangsu China , 211126
| | - Linyu Li
- School of Pharmacy and Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine , Nanjing Medical University , Nanjing , Jiangsu China , 211126
| | - Danjun Fang
- School of Pharmacy and Key Laboratory of Targeted Intervention of Cardiovascular Disease, Collaborative Innovation Center for Cardiovascular Disease Translational Medicine , Nanjing Medical University , Nanjing , Jiangsu China , 211126
| | - Thomas J Kelley
- Departments of Pediatrics , Case Western Reserve University , Cleveland , Ohio 44106 , United States
| | - James D Burgess
- Department of Medical Laboratory, Imaging, and Radiologic Sciences, College of Allied Health Sciences , Augusta University and Augusta University Health System , Augusta , Georgia 30912 , United States
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3
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Li L, Lu B, Jiang D, Shin M, Kelley T, Burgess JD. Cell Plasma Membrane Cholesterol as a Diagnostic. CURRENT OPINION IN ELECTROCHEMISTRY 2017; 2:82-87. [PMID: 28758153 PMCID: PMC5526343 DOI: 10.1016/j.coelec.2017.04.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Cholesterol is a tightly regulated major structural component of the cell plasma membrane (PM) where it forms stoichiometric complexes with phospholipids and sphingolipids. The amount of cholesterol in the PM exhibits a regulatory role in basal activity of several biomolecular processes by direct binding to proteins and by indirect local environmental effects within the PM that are also coupled to overall cellular cholesterol homeostasis. The term "active cholesterol" refers to PM cholesterol not complexed to lipids, a cholesterol state that arises above a threshold mole fraction of cholesterol in the PM. Active cholesterol level in the PM provides a control mechanism for cellular cholesterol homeostasis through its recognition by membrane bound proteins that activate genes of cholesterol synthesis enzymes. Uptake of LDL, production and release of HDL as well as reversible storage of cholesterol in the cytosol by covalent modification are also regulated and dependent on PM cholesterol (thermodynamic) activity: active cholesterol. A number of human disease states have been found to have associated alterations in PM cholesterol and thus a method for its determination is described.
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Affiliation(s)
- Li Li
- Department of Chemistry, Case Western Reserve University, Rainbow Babies and Children's Hospital, Cleveland, Ohio 44106, USA
| | - Binyu Lu
- Department of Chemistry, Case Western Reserve University, Rainbow Babies and Children's Hospital, Cleveland, Ohio 44106, USA
| | - Dechen Jiang
- The State Key Laboratory of Analytical Chemistry for Life Science, Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University, Jiangsu 210093, China
| | - Minchul Shin
- Department of Mechanical Engineering, Georgia Southern University, 201 COBA Dr. Statesboro, GA 30458, USA
| | - Thomas Kelley
- Department of Pediatrics and Pharmacology, Case Western Reserve University, Rainbow Babies and Children's Hospital, Cleveland, Ohio 44106, USA
| | - James D Burgess
- Department of Medical Laboratory, Imaging, and Radiologic Sciences, College of Allied Health Sciences, Augusta University and Augusta University Health System, Health Sciences Campus, 987 St. Sabastian Way, EC-2437, Augusta, Georgia 30912 USA
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Yu X, Kelley TJ, Chiel HJ, Burgess JD. Communication-Microelectrode Detection of Cholesterol Efflux from the Human Buccel Mucosa. JOURNAL OF THE ELECTROCHEMICAL SOCIETY 2016; 163:B453-B455. [PMID: 27546897 PMCID: PMC4988675 DOI: 10.1149/2.1001608jes] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
It has previously demonstrated that cholesterol efflux from the cell plasma membrane is increased in a mouse model of cystic fibrosis (CF) compared to a wild-type control. A noninvasive means of characterizing plasma membrane cholesterol efflux at the surface of airway tissue of CF patients is needed to extend the trends found in animal models of CF to the human disease state. Microelectrode-induced cholesterol efflux from the plasma membrane of cells at the surface of tissue is proposed as a strategy to demonstrate increased cholesterol efflux for CF in human subjects. Data demonstrating detection of cholesterol efflux from the human buccal mucosa is reported as proof-of-concept for an in vivo diagnostic assay.
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Affiliation(s)
- Xiaochun Yu
- Department of Chemistry, Case Western Reserve University and Rainbow Babies and Children's Hospital, Cleveland, Ohio 44106
| | - Thomas J. Kelley
- Department of Pediatrics and Pharmacology, Case Western Reserve University and Rainbow Babies and Children's Hospital, Cleveland, Ohio 44106
| | - Hillel J. Chiel
- Department of Biology, Case Western Reserve University and Rainbow Babies and Children's Hospital, Cleveland, Ohio 44106
| | - James D. Burgess
- Department of Chemistry, Case Western Reserve University and Rainbow Babies and Children's Hospital, Cleveland, Ohio 44106
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Zalewski AN, Nathanael JG, White JM, Wille U. Oxidation of cholesterol and O-protected derivatives by the environmental pollutant NO2˙. Chem Commun (Camb) 2016; 52:4060-3. [DOI: 10.1039/c5cc09663d] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Exposure of O-protected and free cholesterol to NO2˙ leads to oxidation of the alkene moiety through non-radical pathways, demonstrating that ionic processes must be considered when assessing NO2˙ toxicity.
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Affiliation(s)
- A. N. Zalewski
- School of Chemistry
- Bio21 Institute
- The University of Melbourne
- Parkville
- Australia
| | - J. G. Nathanael
- School of Chemistry
- Bio21 Institute
- The University of Melbourne
- Parkville
- Australia
| | - J. M. White
- School of Chemistry
- Bio21 Institute
- The University of Melbourne
- Parkville
- Australia
| | - U. Wille
- School of Chemistry
- Bio21 Institute
- The University of Melbourne
- Parkville
- Australia
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West RH, Lu H, Shaw K, Chiel HJ, Kelley TJ, Burgess JD. Double Potential Pulse Chronocoulometry for Detection of Plasma Membrane Cholesterol Efflux at Disk Platinum Microelectrodes. JOURNAL OF THE ELECTROCHEMICAL SOCIETY 2014; 161:B111-B116. [PMID: 27330196 PMCID: PMC4909259 DOI: 10.1149/2.005406jes] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
A double potential pulse scheme is reported for observation of cholesterol efflux from the plasma membrane of a single neuron cell. Capillary Pt disk microelectrodes having a thin glass insulator allow the 10 μm diameter electrode and cell to be viewed under optical magnification. The electrode, covalently functionalized with cholesterol oxidase, is positioned in contact with the cell surface resulting in enzyme catalyzed cholesterol oxidation and efflux of cholesterol from the plasma membrane at the electrode contact site. Enzymatically generated hydrogen peroxide accumulates at the electrode/cell interface during a 5 s hold-time and is oxidized during application of a potential pulse. A second, replicate potential pulse is applied 0.5 s after the first potential pulse to gauge background charge prior to significant accumulation of hydrogen peroxide. The difference in charge passed between the first and second potential pulse provides a measure of hydrogen peroxide generated by the enzyme and is an indication of the cholesterol efflux. Control experiments for bare Pt microelectrodes in contact with the cell plasma membrane show difference charge signals in the range of about 7-10 pC. Enzyme-modified electrodes in contact with the plasma membrane show signals in the range of 16-26 pC.
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Affiliation(s)
- Richard H. West
- Department of Chemistry, Case Western Reserve University and Rainbow Babies and Children’s Hospital, Cleveland, Ohio 44106
| | - Hui Lu
- Department of Biology, Case Western Reserve University and Rainbow Babies and Children’s Hospital, Cleveland, Ohio 44106
| | - Kendrick Shaw
- Department of Biology, Case Western Reserve University and Rainbow Babies and Children’s Hospital, Cleveland, Ohio 44106
| | - Hillel J. Chiel
- Department of Biology, Case Western Reserve University and Rainbow Babies and Children’s Hospital, Cleveland, Ohio 44106
| | - Thomas J. Kelley
- Department of Pediatrics and Pharmacology, Case Western Reserve University and Rainbow Babies and Children’s Hospital, Cleveland, Ohio 44106
| | - James D. Burgess
- Department of Chemistry, Case Western Reserve University and Rainbow Babies and Children’s Hospital, Cleveland, Ohio 44106
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Freeman MH, Hall JR, Leopold MC. Monolayer-protected nanoparticle doped xerogels as functional components of amperometric glucose biosensors. Anal Chem 2013; 85:4057-65. [PMID: 23472762 DOI: 10.1021/ac3037188] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
First-generation amperometric glucose biosensors incorporating alkanethiolate-protected gold nanoparticles, monolayer protected clusters (MPCs), within a xerogel matrix are investigated as model systems for nanomaterial-assisted electrochemical sensing strategies. The xerogel biosensors are comprised of platinum electrodes modified with composite films of (3-mercaptopropyl)trimethoxy silane xerogel embedded with glucose oxidase enzyme, doped with Au225(C6)75 MPCs, and coated with an outer polyurethane layer. Electrochemistry and scanning/transmission electron microscopy, including cross-sectional TEM, show sensor construction, humidity effects on xerogel structure, and successful incorporation of MPCs. Analytical performance of the biosensor scheme with and without MPC doping of the xerogel is determined from direct glucose injection during amperometry. MPC-doped xerogels yield significant enhancement of several sensor attributes compared to analogous films without nanoparticles: doubling of the linear range, sensitivity enhancement by an order of magnitude, and 4-fold faster response times accompany long-term stability and resistance to common interfering agents that are competitive with current glucose biosensing literature. Ligand chain length and the MPC/silane ratio studies suggest the MPC-induced enhancements are critically related to structure-function relationships, particularly those affecting interparticle electronic communication where the MPC network behaves as a three-dimensional extension of the working electrode into the xerogel film, reducing the system's dependence on diffusion and maximizing efficiency of the sensing mechanism. The integration of MPCs as a functional component of amperometric biosensor schemes has implications for future development of biosensors targeting clinically relevant species.
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Affiliation(s)
- Michael H Freeman
- Department of Chemistry, Gottwald Center for the Sciences, University of Richmond, Richmond, Virginia 23173, United States
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Xu JY, Chen TW, Bao WJ, Wang K, Xia XH. Label-free strategy for in-situ analysis of protein binding interaction based on attenuated total reflection surface enhanced infrared absorption spectroscopy (ATR-SEIRAS). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2012; 28:17564-17570. [PMID: 23163643 DOI: 10.1021/la303054w] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
A versatile ATR-SEIRAS methodology is described herein for highly sensitive analysis of immunoglobulin (IgG) recognition. This strategy allows in situ tracking of specific protein binding at the liquid-solid interface. Most importantly, interferential signal from environmental molecules (e.g., water, nonspecific binding molecules, and bulk molecules) can be eliminated to negligible levels by using the ATR analysis mode, and the sensitive IR structural information of target proteins is obtained simultaneously. A simplified numerical model has been established to quantitatively describe the kinetics and thermodynamics of protein recognition processes at surfaces. Compared with conventional label-free methods for protein binding study, experimental results obtained from IR spectroscopic information are more reliable. The presented ATR-SEIRAS method is powerful in studying surface limited protein binding reactions.
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Affiliation(s)
- Jian-Yun Xu
- State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210093, People's Republic of China
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9
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Fang D, West RH, Manson ME, Ruddy J, Jiang D, Previs SF, Sonawane ND, Burgess JD, Kelley TJ. Increased plasma membrane cholesterol in cystic fibrosis cells correlates with CFTR genotype and depends on de novo cholesterol synthesis. Respir Res 2010; 11:61. [PMID: 20487541 PMCID: PMC2880018 DOI: 10.1186/1465-9921-11-61] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2010] [Accepted: 05/20/2010] [Indexed: 01/12/2023] Open
Abstract
Background Previous observations demonstrate that Cftr-null cells and tissues exhibit alterations in cholesterol processing including perinuclear cholesterol accumulation, increased de novo synthesis, and an increase in plasma membrane cholesterol accessibility compared to wild type controls. The hypothesis of this study is that membrane cholesterol accessibility correlates with CFTR genotype and is in part influenced by de novo cholesterol synthesis. Methods Electrochemical detection of cholesterol at the plasma membrane is achieved with capillary microelectrodes with a modified platinum coil that accepts covalent attachment of cholesterol oxidase. Modified electrodes absent cholesterol oxidase serves as a baseline control. Cholesterol synthesis is determined by deuterium incorporation into lipids over time. Incorporation into cholesterol specifically is determined by mass spectrometry analysis. All mice used in the study are on a C57Bl/6 background and are between 6 and 8 weeks of age. Results Membrane cholesterol measurements are elevated in both R117H and ΔF508 mouse nasal epithelium compared to age-matched sibling wt controls demonstrating a genotype correlation to membrane cholesterol detection. Expression of wt CFTR in CF epithelial cells reverts membrane cholesterol to WT levels further demonstrating the impact of CFTR on these processes. In wt epithelial cell, the addition of the CFTR inhibitors, Gly H101 or CFTRinh-172, for 24 h surprisingly results in an initial drop in membrane cholesterol measurement followed by a rebound at 72 h suggesting a feedback mechanism may be driving the increase in membrane cholesterol. De novo cholesterol synthesis contributes to membrane cholesterol accessibility. Conclusions The data in this study suggest that CFTR influences cholesterol trafficking to the plasma membrane, which when depleted, leads to an increase in de novo cholesterol synthesis to restore membrane content.
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Affiliation(s)
- Danjun Fang
- Department of Pediatrics and Pharmacology, Case Western Reserve University, Cleveland, OH 44106, USA
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Ding J, Jiang D, Kurczy M, Nalepka J, Dudley B, Merkel EI, Porter FD, Ewing AG, Winograd N, Burgess J, Molyneaux K. Inhibition of HMG CoA reductase reveals an unexpected role for cholesterol during PGC migration in the mouse. BMC DEVELOPMENTAL BIOLOGY 2008; 8:120. [PMID: 19117526 PMCID: PMC2631600 DOI: 10.1186/1471-213x-8-120] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/17/2008] [Accepted: 12/31/2008] [Indexed: 11/10/2022]
Abstract
BACKGROUND Primordial germ cells (PGCs) are the embryonic precursors of the sperm and eggs. Environmental or genetic defects that alter PGC development can impair fertility or cause formation of germ cell tumors. RESULTS We demonstrate a novel role for cholesterol during germ cell migration in mice. Cholesterol was measured in living tissue dissected from mouse embryos and was found to accumulate within the developing gonads as germ cells migrate to colonize these structures. Cholesterol synthesis was blocked in culture by inhibiting the activity of HMG CoA reductase (HMGCR) resulting in germ cell survival and migration defects. These defects were rescued by co-addition of isoprenoids and cholesterol, but neither compound alone was sufficient. In contrast, loss of the last or penultimate enzyme in cholesterol biosynthesis did not alter PGC numbers or position in vivo. However embryos that lack these enzymes do not exhibit cholesterol defects at the stage at which PGCs are migrating. This demonstrates that during gestation, the cholesterol required for PGC migration can be supplied maternally. CONCLUSION In the mouse, cholesterol is required for PGC survival and motility. It may act cell-autonomously by regulating clustering of growth factor receptors within PGCs or non cell-autonomously by controlling release of growth factors required for PGC guidance and survival.
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Affiliation(s)
- Jiaxi Ding
- Department of Genetics Case Western Reserve University, Cleveland, OH, USA
| | - DeChen Jiang
- Department of Chemistry, Case Western Reserve University, Cleveland, OH, USA
| | - Michael Kurczy
- Department of Chemistry, Penn State University, University Park, PA, USA
| | - Jennifer Nalepka
- Department of Genetics Case Western Reserve University, Cleveland, OH, USA
| | - Brian Dudley
- Department of Genetics Case Western Reserve University, Cleveland, OH, USA
| | - Erin I Merkel
- Program on Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Forbes D Porter
- Program on Developmental Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
| | - Andrew G Ewing
- Department of Chemistry, Penn State University, University Park, PA, USA
- Department of Chemistry, Gothenburg University, Kemivägen 4, SE-41296 Gothenburg, Sweden
| | - Nicholas Winograd
- Department of Chemistry, Penn State University, University Park, PA, USA
| | - James Burgess
- Department of Chemistry, Case Western Reserve University, Cleveland, OH, USA
| | - Kathleen Molyneaux
- Department of Genetics Case Western Reserve University, Cleveland, OH, USA
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Cystic fibrosis as a bowel cancer syndrome and the potential role of CK2. Mol Cell Biochem 2008; 316:169-75. [PMID: 18604476 PMCID: PMC2629510 DOI: 10.1007/s11010-008-9815-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2008] [Accepted: 05/29/2008] [Indexed: 11/16/2022]
Abstract
Chloride is critical in creating differential pH values inside various organelles (Golgi for example) by linking ATP hydrolysis to trans-bilayer proton movement. This proton-ATPase drives anions such as chloride through unrelated channels in the endosomal/organellar bilayer thus loading HCl into different lipid-encased cellular compartments. Critically, intraorganellar pH (and ion channel content/activities) differs during different phases of the cell cycle. The cystic fibrosis (CF) chloride channel protein CFTR is a member of the ABC family (ABCC7) and resides in many endosomal membranes trafficking to the epithelial surface and back again. Recently, it has become clear that human CF has an unusually high incidence of cancer in the bowel with correspondingly elevated gut epithelial proliferation rates observed in CF mice. In this review, emphasis is placed on CK2 & CF because CK2 controls not only proliferation but also four different members of the ABC superfamily including the multi-drug resistance protein P-glycoprotein and CFTR itself. In addition, CK2 also regulates a critical cancer-relevant and CFTR-regulated cation channel (ENaC) that mediates the cellular accumulation of sodium ions within epithelia such as the colon and lung. Not only are ENaC and CFTR both abnormal in CF cells, but ENaC also ‘carries’ CK2 to the cell membrane in oocytes, only provided its two target phosphosites are intact. CK2 may be a critical regulator of cell proliferation in conjunction with regulation of ion channels such as CFTR, other ABC members and the cation channel ENaC. The emerging idea is that CFTR may control membrane-CK2 as much as membrane-CK2 controls CFTR.
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