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Reich N, Parkin E, Dawson N. Liposome nanoparticle conjugation and cell penetrating peptide sequences (CPPs) enhance the cellular delivery of the tau aggregation inhibitor RI-AG03. J Cell Mol Med 2024; 28:e18477. [PMID: 38853458 PMCID: PMC11163028 DOI: 10.1111/jcmm.18477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 05/23/2024] [Accepted: 05/26/2024] [Indexed: 06/11/2024] Open
Abstract
Given the pathological role of Tau aggregation in Alzheimer's disease (AD), our laboratory previously developed the novel Tau aggregation inhibitor peptide, RI-AG03. As Tau aggregates accumulate intracellularly, it is essential that the peptide can traverse the cell membrane. Here we examine the cellular uptake and intracellular trafficking of RI-AG03, in both a free and liposome-conjugated form. We also characterize the impact of adding the cell-penetrating peptide (CPP) sequences, polyarginine (polyR) or transactivator of transcription (TAT), to RI-AG03. Our data show that liposome conjugation of CPP containing RI-AG03 peptides, with either the polyR or TAT sequence, increased cellular liposome association three-fold. Inhibition of macropinocytosis modestly reduced the uptake of unconjugated and RI-AG03-polyR-linked liposomes, while having no effect on RI-AG03-TAT-conjugated liposome uptake. Further supporting macropinocytosis-mediated internalization, a 'fair' co-localisation of the free and liposome-conjugated RI-AG03-polyR peptide with macropinosomes and lysosomes was observed. Interestingly, we also demonstrate that RI-AG03-polyR detaches from liposomes following cellular uptake, thereby largely evading organellar entrapment. Collectively, our data indicate that direct membrane penetration and macropinocytosis are key routes for the internalization of liposomes conjugated with CPP containing RI-AG03. Our study also demonstrates that peptide-liposomes are suitable nanocarriers for the cellular delivery of RI-AG03, furthering their potential use in targeting Tau pathology in AD.
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Affiliation(s)
- Niklas Reich
- Division of Biomedical and Life Sciences, Faculty of Health and MedicineLancaster UniversityLancasterUK
| | - Edward Parkin
- Division of Biomedical and Life Sciences, Faculty of Health and MedicineLancaster UniversityLancasterUK
| | - Neil Dawson
- Division of Biomedical and Life Sciences, Faculty of Health and MedicineLancaster UniversityLancasterUK
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2
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Petrov AM. Oxysterols in Central and Peripheral Synaptic Communication. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 1440:91-123. [PMID: 38036877 DOI: 10.1007/978-3-031-43883-7_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2023]
Abstract
Cholesterol is a key molecule for synaptic transmission, and both central and peripheral synapses are cholesterol rich. During intense neuronal activity, a substantial portion of synaptic cholesterol can be oxidized by either enzymatic or non-enzymatic pathways to form oxysterols, which in turn modulate the activities of neurotransmitter receptors (e.g., NMDA and adrenergic receptors), signaling molecules (nitric oxide synthases, protein kinase C, liver X receptors), and synaptic vesicle cycling involved in neurotransmitters release. 24-Hydroxycholesterol, produced by neurons in the brain, could directly affect neighboring synapses and change neurotransmission. 27-Hydroxycholesterol, which can cross the blood-brain barrier, can alter both synaptogenesis and synaptic plasticity. Increased generation of 25-hydroxycholesterol by activated microglia and macrophages could link inflammatory processes to learning and neuronal regulation. Amyloids and oxidative stress can lead to an increase in the levels of ring-oxidized sterols and some of these oxysterols (4-cholesten-3-one, 5α-cholestan-3-one, 7β-hydroxycholesterol, 7-ketocholesterol) have a high potency to disturb or modulate neurotransmission at both the presynaptic and postsynaptic levels. Overall, oxysterols could be used as "molecular prototypes" for therapeutic approaches. Analogs of 24-hydroxycholesterol (SGE-301, SGE-550, SAGE718) can be used for correction of NMDA receptor hypofunction-related states, whereas inhibitors of cholesterol 24-hydroxylase, cholestane-3β,5α,6β-triol, and cholest-4-en-3-one oxime (olesoxime) can be utilized as potential anti-epileptic drugs and (or) protectors from excitotoxicity.
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Affiliation(s)
- Alexey M Petrov
- Laboratory of Biophysics of Synaptic Processes, Kazan Institute of Biochemistry and Biophysics, Federal Research Center "Kazan Scientific Center of RAS", Kazan, RT, Russia.
- Kazan State Medial University, Kazan, RT, Russia.
- Kazan Federal University, Kazan, RT, Russia.
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3
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Sharma A, Seal A, Iyer SS, Srivastava A. Enthalpic and entropic contributions to interleaflet coupling drive domain registration and antiregistration in biological membrane. Phys Rev E 2022; 105:044408. [PMID: 35590589 DOI: 10.1103/physreve.105.044408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2021] [Accepted: 03/14/2022] [Indexed: 06/15/2023]
Abstract
Biological membrane is a complex self-assembly of lipids, sterols, and proteins organized as a fluid bilayer of two closely stacked lipid leaflets. Differential molecular interactions among its diverse constituents give rise to heterogeneities in the membrane lateral organization. Under certain conditions, heterogeneities in the two leaflets can be spatially synchronized and exist as registered domains across the bilayer. Several contrasting theories behind mechanisms that induce registration of nanoscale domains have been suggested. Following a recent study showing the effect of position of lipid tail unsaturation on domain registration behavior, we decided to develop an analytical theory to elucidate the driving forces that create and maintain domain registry across leaflets. Towards this, we formulated a Hamiltonian for a stacked lattice system where site variables capture the lipid molecular properties such as the position of unsaturation and various other interactions that could drive phase separation and interleaflet coupling. We solve the Hamiltonian using Monte Carlo simulations and create a complete phase diagram that reports the presence or absence of registered domains as a function of various Hamiltonian parameters. We find that the interleaflet coupling should be described as a competing enthalpic contribution due to interaction of lipid tail termini, primarily due to saturated-saturated interactions, and an interleaflet entropic contribution from overlap of unsaturated tail termini. A higher position of unsaturation is seen to provide weaker interleaflet coupling. Thermodynamically stable nanodomains could also be observed for certain points in the parameter space in our bilayer model, which were further verified by carrying out extended Monte Carlo simulations. These persistent noncoalescing registered nanodomains close to the lower end of the accepted nanodomain size range also point towards a possible "nanoscale" emulsion description of lateral heterogeneities in biological membrane leaflets.
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Affiliation(s)
- Akshara Sharma
- Department of Physics, Indian Institute of Science-Bangalore, C. V. Raman Road, Bangalore, Karnataka 560012, India
| | - Aniruddha Seal
- School of Chemical Sciences, National Institute of Science Education and Research, Bhubaneswar, Khurda, Odisha 752050, India
| | - Sahithya S Iyer
- Molecular Biophysics Unit, Indian Institute of Science-Bangalore, C. V. Raman Road, Bangalore, Karnataka 560012, India
| | - Anand Srivastava
- Molecular Biophysics Unit, Indian Institute of Science-Bangalore, C. V. Raman Road, Bangalore, Karnataka 560012, India
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4
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Jia W, Fan Z, Du A, Shi L. Untargeted foodomics reveals molecular mechanism of magnetic field effect on Feng-flavor Baijiu ageing. Food Res Int 2021; 149:110681. [PMID: 34600683 DOI: 10.1016/j.foodres.2021.110681] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2021] [Revised: 08/25/2021] [Accepted: 08/28/2021] [Indexed: 12/23/2022]
Abstract
Ageing is a time-consuming step in Baijiu manufacture, stimulating an urgent requirement of optimization. Variation of artificial aged Feng-flavor Baijiu by inhomogeneous alternating magnetic field was investigated through quantitative foodomics combined with confirmed ultra high performance liquid chromatography quadrupole-orbitaltrap high resolution mass spectrometry (UHPLC-Q-Orbitrap). A total of 153 substances were identified with significant variables (p < 0.05, VIP > 1) and 16 metabolic pathways related to Feng-flavor Baijiu functions were obtained. The method showed good accuracy with recovery values between 80.4% and 117.4% and precision lower than 9.8% for all characteristic substances. Limit of detection (LOD) was ranging between 1.6 and 10.0 μg/L with R2 ≥ 0.99. Factor analysis demonstrated that ageing degree of magnetized samples increased with rise of magnetic field intensity and the maximum effect was equivalent to 12.81 years of natural ageing. The results of stoichiometric analysis revealed that regulation of magnetic field on proportion in Baijiu was mainly performed through entropy and the hydrogen bond strength of Baijiu molecules. Sensory evaluation illustrated that score of Baijiu samples reached the highest at 150 mT, demonstrating that magnetic field treatment can be considered as an optimized ageing means for Feng-flavor Baijiu.
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Affiliation(s)
- Wei Jia
- School of Food and Biological Engineering, Shaanxi University of Science & Technology, Xi'an 710021, China; Shaanxi Research Institute of Agricultural Products Processing Technology, Xi'an 710021, China.
| | - Zibian Fan
- School of Food and Biological Engineering, Shaanxi University of Science & Technology, Xi'an 710021, China
| | - An Du
- School of Food and Biological Engineering, Shaanxi University of Science & Technology, Xi'an 710021, China
| | - Lin Shi
- School of Food and Biological Engineering, Shaanxi University of Science & Technology, Xi'an 710021, China
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5
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Preferential Protein Partitioning in Biological Membrane with Coexisting Liquid Ordered and Liquid Disordered Phase Behavior: Underlying Design Principles. J Membr Biol 2020; 253:551-562. [PMID: 33170308 DOI: 10.1007/s00232-020-00150-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 10/31/2020] [Indexed: 12/17/2022]
Abstract
Several studies now show that certain proteins exhibit selective preference toward liquid ordered (L[Formula: see text]) or toward liquid disordered (L[Formula: see text]) regions of the heterogeneous membrane and some of them have preference for the L[Formula: see text]-L[Formula: see text] interface. Spatially heterogenous organization of lipids, enriched in specific protein molecules, function as platforms for signaling and are involved in several other physiologically critical functions. In this review, we collate together some of the experimental observations of cases where proteins preferentially segregate into different phases and highlight the importance of these preferential localization in terms of underlying functions. We also try to understand the structural features and chemical makeup of the membrane-interacting motifs of these proteins. Finally, we put forth some preliminary analysis on class I viral fusion proteins, some of which are known to partition at the L[Formula: see text]-L[Formula: see text] interface, and through them we try to understand the evolutionary design principles of phase segregating proteins. Put together, this review summarizes the existing studies on preferential partitioning of proteins into different membrane phases while emphasizing the need to understand the molecular design-level features that can help us "engineer" functionally rich peptides and proteins with a programmed membrane partitioning.
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6
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Banerjee M, Arutyunov D, Brandwein D, Janetzki-Flatt C, Kolski H, Hume S, Leonard NJ, Watt J, Lacson A, Baradi M, Leslie EM, Cordat E, Caluseriu O. The novel p.Ser263Phe mutation in the human high-affinity choline transporter 1 (CHT1/SLC5A7) causes a lethal form of fetal akinesia syndrome. Hum Mutat 2019; 40:1676-1683. [PMID: 31299140 DOI: 10.1002/humu.23828] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 05/04/2019] [Accepted: 05/27/2019] [Indexed: 11/07/2022]
Abstract
A subset of a larger and heterogeneous class of disorders, the congenital myasthenic syndromes (CMS) are caused by pathogenic variants in genes encoding proteins that support the integrity and function of the neuromuscular junction (NMJ). A central component of the NMJ is the sodium-dependent high-affinity choline transporter 1 (CHT1), a solute carrier protein (gene symbol SLC5A7), responsible for the reuptake of choline into nerve termini has recently been implicated as one of several autosomal recessive causes of CMS. We report the identification and functional characterization of a novel pathogenic variant in SLC5A7, c.788C>T (p.Ser263Phe) in an El Salvadorian family with a lethal form of a congenital myasthenic syndrome characterized by fetal akinesia. This study expands the clinical phenotype and insight into a form of fetal akinesia related to CHT1 defects and proposes a genotype-phenotype correlation for the lethal form of SLC5A7-related disorder with potential implications for genetic counseling.
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Affiliation(s)
- Mayukh Banerjee
- Department of Physiology and Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Denis Arutyunov
- Department of Physiology and Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Daniel Brandwein
- Department of Physiology and Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | | | - Hanna Kolski
- Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
| | - Stacey Hume
- Department of Medical Genetics, University of Alberta, Edmonton, Alberta, Canada
| | - Norma Jean Leonard
- Department of Medical Genetics, University of Alberta, Edmonton, Alberta, Canada.,Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
| | - James Watt
- Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
| | - Atilano Lacson
- Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada
| | - Monica Baradi
- Department of Physiology and Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Elaine M Leslie
- Department of Physiology and Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada.,Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada
| | - Emmanuelle Cordat
- Department of Physiology and Membrane Protein Disease Research Group, University of Alberta, Edmonton, Alberta, Canada
| | - Oana Caluseriu
- Department of Medical Genetics, University of Alberta, Edmonton, Alberta, Canada.,Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada
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7
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Parsons TK, Pratt RN, Tang L, Wu Y. An active and selective molecular mechanism mediating the uptake of sex steroids by prostate cancer cells. Mol Cell Endocrinol 2018; 477:121-131. [PMID: 29928927 DOI: 10.1016/j.mce.2018.06.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 05/31/2018] [Accepted: 06/16/2018] [Indexed: 12/21/2022]
Abstract
Steroid hormones play important roles in normal physiological functions and diseases. Sex steroids hormones are important in the biology and treatment of sex hormone-related cancer such as prostate cancer and breast cancer. Cells may take up steroids using multiple mechanisms. The conventionally accepted hypothesis that steroids cross cell membrane through passive diffusion has not been tested rigorously. Experimental data suggested that cells may take up sex steroid using an active uptake mechanism. 3H-testosterone uptake by prostate cancer cells showed typical transporter-mediated uptake kinetic. Cells retained testosterone taken up from the medium. The uptake of testosterone was selective for certain steroid hormones but not others. Data also indicated that the active and selective uptake mechanism resided in cholesterol-rich membrane domains, and may involve ATP and membrane transporters. In summary, the present study provided strong evidence to support the existence of an active and selective molecular mechanism for sex steroid uptake.
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Affiliation(s)
- Todd K Parsons
- Department of Urology, Roswell Park Comprehensive Cancer Center, Elm and Carlton Streets, Buffalo, NY, 14263, USA
| | - Rachel N Pratt
- Department of Cancer Prevention and Control, Roswell Park Comprehensive Cancer Center, Elm and Carlton Streets, Buffalo, NY, 14263, USA
| | - Li Tang
- Department of Cancer Prevention and Control, Roswell Park Comprehensive Cancer Center, Elm and Carlton Streets, Buffalo, NY, 14263, USA
| | - Yue Wu
- Department of Urology, Roswell Park Comprehensive Cancer Center, Elm and Carlton Streets, Buffalo, NY, 14263, USA.
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8
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Kristofikova Z, Ricny J, Soukup O, Korabecny J, Nepovimova E, Kuca K, Ripova D. Inhibitors of Acetylcholinesterase Derived from 7-Methoxytacrine and Their Effects on the Choline Transporter CHT1. Dement Geriatr Cogn Disord 2018; 43:45-58. [PMID: 27988521 DOI: 10.1159/000453256] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/08/2016] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Reversible acetylcholinesterase inhibitors are used in Alzheimer disease therapy. However, tacrine and its derivatives have severe side effects. Derivatives of the tacrine analogue 7-methoxytacrine (MEOTA) are less toxic. METHODS We evaluated new derivatives of 7-MEOTA (2 homodimers linked by 2 C4-C5 chains and 5 N-alkylated C4-C8 side chain derivatives) in vitro, using the rat hippocampal choline transporter CHT1. RESULTS Some derivatives were effective inhibitors of rat acetylcholinesterase and comparable with 7-MEOTA. All derivatives were able to inhibit CHT1, probably via quaternary ammonium, and this interaction could be involved in the enhancement of their detrimental side effects and/or in the attenuation of their promising effects. Under conditions of disrupted lipid rafts, the unfavorable effects of some derivatives were weakened. Only tacrine was probably able to stereospecifically interact with the naturally occurring amyloid-β isoform and to simultaneously stimulate CHT1. Some derivatives, when coincubated with amyloid β, did not influence CHT1. All derivatives also increased the fluidity of the cortical membranes. CONCLUSION The N-alkylated derivative of 7-MEOTA bearing from C4 side chains appears to be the most promising compound and should be evaluated in future in vivo research.
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Affiliation(s)
- Zdenka Kristofikova
- Alzheimer Disease Center, National Institute of Mental Health, Klecany, Czech Republic
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9
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McMillin M, Grant S, Frampton G, Petrescu AD, Kain J, Williams E, Haines R, Canady L, DeMorrow S. FXR-Mediated Cortical Cholesterol Accumulation Contributes to the Pathogenesis of Type A Hepatic Encephalopathy. Cell Mol Gastroenterol Hepatol 2018; 6:47-63. [PMID: 29928671 PMCID: PMC6008252 DOI: 10.1016/j.jcmgh.2018.02.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 02/26/2018] [Indexed: 12/13/2022]
Abstract
BACKGROUND & AIMS Hepatic encephalopathy is a serious neurologic complication of acute and chronic liver diseases. We previously showed that aberrant bile acid signaling contributes to the development of hepatic encephalopathy via farnesoid X receptor (FXR)-mediated mechanisms in neurons. In the brain, a novel alternative bile acid synthesis pathway, catalyzed by cytochrome p450 46A1 (Cyp46A1), is the primary mechanism by which the brain regulates cholesterol homeostasis. The aim of this study was to determine if FXR activation in the brain altered cholesterol homeostasis during hepatic encephalopathy. METHODS Cyp7A1-/- mice or C57Bl/6 mice pretreated with central infusion of FXR vivo morpholino, 2-hydroxypropyl-β-cyclodextrin, or fed a cholestyramine-supplemented diet were injected with azoxymethane (AOM). Cognitive and neuromuscular impairment as well as liver damage and expression of Cyp46A1 were assessed using standard techniques. The subsequent cholesterol content in the frontal cortex was measured using commercially available kits and by Filipin III and Nile Red staining. RESULTS There was an increase in membrane-bound and intracellular cholesterol in the cortex of mice treated with AOM that was associated with decreased Cyp46A1 expression. Strategies to inhibit FXR signaling prevented the down-regulation of Cyp46A1 and the accumulation of cholesterol. Treatment of mice with 2-hydroxypropyl-β-cyclodextrin attenuated the AOM-induced cholesterol accumulation in the brain and the cognitive and neuromuscular deficits without altering the underlying liver pathology. CONCLUSIONS During hepatic encephalopathy, FXR signaling increases brain cholesterol and contributes to neurologic decline. Targeting cholesterol accumulation in the brain may be a possible therapeutic target for the management of hepatic encephalopathy.
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Key Words
- 2-HβC, 2-hypdroxypropyl-β-cyclodextrin
- AOM, azoxymethane
- Acute Liver Failure
- Azoxymethane
- CYP46A1, cytochrome p450 46A1
- CYP7A1, cytochrome p450 7A1
- Cytochrome p450 46A1
- FXR, farnesoid X receptor
- Farnesoid X Receptor
- GAPDH, glyceraldehyde-3-phosphate dehydrogenase
- PBS, phosphate-buffered saline
- PFA, paraformaldehyde
- RT-PCR, reverse-transcription polymerase chain reaction
- WT, wild-type
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Affiliation(s)
- Matthew McMillin
- Central Texas Veterans Healthcare System, Temple, Texas,Department of Medical Physiology, Texas A&M College of Medicine, Temple, Texas
| | - Stephanie Grant
- Central Texas Veterans Healthcare System, Temple, Texas,Department of Medical Physiology, Texas A&M College of Medicine, Temple, Texas
| | - Gabriel Frampton
- Central Texas Veterans Healthcare System, Temple, Texas,Department of Medical Physiology, Texas A&M College of Medicine, Temple, Texas
| | - Anca D. Petrescu
- Central Texas Veterans Healthcare System, Temple, Texas,Department of Medical Physiology, Texas A&M College of Medicine, Temple, Texas
| | - Jessica Kain
- Central Texas Veterans Healthcare System, Temple, Texas,Department of Medical Physiology, Texas A&M College of Medicine, Temple, Texas
| | - Elaina Williams
- Central Texas Veterans Healthcare System, Temple, Texas,Department of Medical Physiology, Texas A&M College of Medicine, Temple, Texas
| | - Rebecca Haines
- Department of Medical Physiology, Texas A&M College of Medicine, Temple, Texas
| | - Lauren Canady
- Department of Medical Physiology, Texas A&M College of Medicine, Temple, Texas
| | - Sharon DeMorrow
- Central Texas Veterans Healthcare System, Temple, Texas,Department of Medical Physiology, Texas A&M College of Medicine, Temple, Texas,Correspondence Address correspondence to: Sharon DeMorrow, PhD, Department of Medical Physiology, Texas A&M Health Science Center, Central Texas Veterans Health Care System, Building 205, 1901 South 1st Street, Temple, Texas 76504. fax: (254) 743-0378.
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10
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Dou X, Li Y, Han J, Zarlenga DS, Zhu W, Ren X, Dong N, Li X, Li G. Cholesterol of lipid rafts is a key determinant for entry and post-entry control of porcine rotavirus infection. BMC Vet Res 2018; 14:45. [PMID: 29433482 PMCID: PMC5809846 DOI: 10.1186/s12917-018-1366-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 01/28/2018] [Indexed: 12/26/2022] Open
Abstract
Background Lipid rafts are major structural components in plasma membranes that play critical roles in many biological processes including virus infection. However, few reports have described the relationship between lipid rafts and porcine rotavirus (PRV) infection. In this study, we investigated whether or not the locally high concentrations (3–5 fold) of cholesterol present in lipid rafts are required for PRV infection, and further examined which stages of the infection process are most affected. Results When cellular cholesterol was depleted by methyl-β-cyclodextrin (MβCD), PRV infectivity significantly declined in a dose-dependent manner. This inhibition was partially reversed upon reintroduction of cholesterol into the system. This was corroborated by the co-localization of PRV with a recombinant, GPI-anchored green fluorescent protein, which functioned as a marker for membranous regions high in cholesterol and indicative of lipid rafts. Changes in virus titer and western blot analyses indicated that depletion of cellular cholesterol with MβCD had no apparent effect on PRV adsorption; however, depletion of cholesterol significantly restricted entry and post-entry of PRV into the cell. Both points of inhibition were restored to near normal levels by the addition of exogenous cholesterol. Conclusions We conclude from these studies that membrane-based cholesterol and in particular that localized to lipid rafts, is an indispensable biomolecule for PRV infection, and that cholesterol-based control of the infection process takes place during entry and immediately post-entry into the cell.
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Affiliation(s)
- Xiujing Dou
- Northeast Agricultural University, No. 59 Mucai Street, Xiangfang District, Harbin, 150030, China
| | - Yang Li
- Northeast Agricultural University, No. 59 Mucai Street, Xiangfang District, Harbin, 150030, China
| | - Junlan Han
- Northeast Agricultural University, No. 59 Mucai Street, Xiangfang District, Harbin, 150030, China
| | - Dante S Zarlenga
- Animal Parasitic Diseases Laboratory, Agricultural Research Service, United States Department of Agriculture, Building 1180, BARC-East, Beltsville, MD, 20705, USA
| | - Weijuan Zhu
- Northeast Agricultural University, No. 59 Mucai Street, Xiangfang District, Harbin, 150030, China
| | - Xiaofeng Ren
- Northeast Agricultural University, No. 59 Mucai Street, Xiangfang District, Harbin, 150030, China
| | - Na Dong
- Northeast Agricultural University, No. 59 Mucai Street, Xiangfang District, Harbin, 150030, China
| | - Xunliang Li
- Northeast Agricultural University, No. 59 Mucai Street, Xiangfang District, Harbin, 150030, China.
| | - Guangxing Li
- Northeast Agricultural University, No. 59 Mucai Street, Xiangfang District, Harbin, 150030, China.
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11
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Cuddy LK, Seah C, Pasternak SH, Rylett RJ. Amino-Terminal β-Amyloid Antibody Blocks β-Amyloid-Mediated Inhibition of the High-Affinity Choline Transporter CHT. Front Mol Neurosci 2017; 10:361. [PMID: 29163036 PMCID: PMC5681948 DOI: 10.3389/fnmol.2017.00361] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2017] [Accepted: 10/19/2017] [Indexed: 11/13/2022] Open
Abstract
Alzheimer's disease (AD) is a common age-related neurodegenerative disorder that is characterized by progressive cognitive decline. The deficits in cognition and attentional processing that are observed clinically in AD are linked to impaired function of cholinergic neurons that release the neurotransmitter acetylcholine (ACh). The high-affinity choline transporter (CHT) is present at the presynaptic cholinergic nerve terminal and is responsible for the reuptake of choline produced by hydrolysis of ACh following its release. Disruption of CHT function leads to decreased choline uptake and ACh synthesis, leading to impaired cholinergic neurotransmission. We report here that cell-derived β-amyloid peptides (Aβ) decrease choline uptake activity and cell surface CHT protein levels in SH-SY5Y neural cells. Moreover, we make the novel observation that the amount of CHT protein localizing to early endosomes and lysosomes is decreased significantly in cells that have been treated with cell culture medium that contains Aβ peptides released from neural cells. The Aβ-mediated loss of CHT proteins from lysosomes is prevented by blocking lysosomal degradation of CHT with the lysosome inhibitor bafilomycin A1 (BafA1). BafA1 also attenuated the Aβ-mediated decrease in CHT cell surface expression. Interestingly, however, lysosome inhibition did not block the effect of Aβ on CHT activity. Importantly, neutralizing Aβ using an anti-Aβ antibody directed at the N-terminal amino acids 1-16 of Aβ, but not by an antibody directed at the mid-region amino acids 22-35 of Aβ, attenuates the effect of Aβ on CHT activity and trafficking. This indicates that a specific N-terminal Aβ epitope, or specific conformation of soluble Aβ, may impair CHT activity. Therefore, Aβ immunotherapy may be a more effective therapeutic strategy for slowing the progression of cognitive decline in AD than therapies designed to promote CHT cell surface levels.
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Affiliation(s)
- Leah K Cuddy
- Molecular Medicine Research Laboratories, Robarts Research Institute, University of Western Ontario, London, ON, Canada.,Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada.,Department of Neurology, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Claudia Seah
- Molecular Medicine Research Laboratories, Robarts Research Institute, University of Western Ontario, London, ON, Canada
| | - Stephen H Pasternak
- Molecular Medicine Research Laboratories, Robarts Research Institute, University of Western Ontario, London, ON, Canada.,Department of Clinical Neurological Sciences, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada
| | - R Jane Rylett
- Molecular Medicine Research Laboratories, Robarts Research Institute, University of Western Ontario, London, ON, Canada.,Department of Physiology and Pharmacology, Schulich School of Medicine & Dentistry, University of Western Ontario, London, ON, Canada
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12
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Choudhary P, Armstrong EJ, Jorgensen CC, Piotrowski M, Barthmes M, Torella R, Johnston SE, Maruyama Y, Janiszewski JS, Storer RI, Skerratt SE, Benn CL. Discovery of Compounds that Positively Modulate the High Affinity Choline Transporter. Front Mol Neurosci 2017; 10:40. [PMID: 28289374 PMCID: PMC5326799 DOI: 10.3389/fnmol.2017.00040] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Accepted: 02/03/2017] [Indexed: 01/09/2023] Open
Abstract
Cholinergic hypofunction is associated with decreased attention and cognitive deficits in the central nervous system in addition to compromised motor function. Consequently, stimulation of cholinergic neurotransmission is a rational therapeutic approach for the potential treatment of a variety of neurological conditions. High affinity choline uptake (HACU) into acetylcholine (ACh)-synthesizing neurons is critically mediated by the sodium- and pH-dependent high-affinity choline transporter (CHT, encoded by the SLC5A7 gene). This transporter is comparatively well-characterized but otherwise unexplored as a potential drug target. We therefore sought to identify small molecules that would enable testing of the hypothesis that positive modulation of CHT mediated transport would enhance activity-dependent cholinergic signaling. We utilized existing and novel screening techniques for their ability to reveal both positive and negative modulation of CHT using literature tools. A screening campaign was initiated with a bespoke compound library comprising both the Pfizer Chemogenomic Library (CGL) of 2,753 molecules designed specifically to help enable the elucidation of new mechanisms in phenotypic screens and 887 compounds from a virtual screening campaign to select molecules with field-based similarities to reported negative and positive allosteric modulators. We identified a number of previously unknown active and structurally distinct molecules that could be used as tools to further explore CHT biology or as a starting point for further medicinal chemistry.
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Affiliation(s)
| | | | | | | | | | | | | | - Yuya Maruyama
- Central Research Laboratory, Kissei Pharmaceutical Co., Ltd. Nagano, Japan
| | | | - R Ian Storer
- Pfizer, Worldwide Medicinal Chemistry Cambridge, UK
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Lu JC, Chiang YT, Lin YC, Chang YT, Lu CY, Chen TY, Yeh CS. Disruption of Lipid Raft Function Increases Expression and Secretion of Monocyte Chemoattractant Protein-1 in 3T3-L1 Adipocytes. PLoS One 2016; 11:e0169005. [PMID: 28030645 PMCID: PMC5193455 DOI: 10.1371/journal.pone.0169005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 12/11/2016] [Indexed: 12/13/2022] Open
Abstract
The adipocyte is unique in its capacity to store lipids. In addition to triglycerides, the adipocyte stores a significant amount of cholesterol. Moreover, obese adipocytes are characterized by a redistribution of cholesterol with depleted cholesterol in the plasma membrane, suggesting that cholesterol perturbation may play a role in adipocyte dysfunction. We used methyl-β-cyclodextrin (MβCD), a molecule with high affinity for cholesterol, to rapidly deplete cholesterol level in differentiated 3T3-L1 adipocytes. We tested whether this perturbation altered adipocyte secretion of monocyte chemoattractant protein-1 (MCP-1), a chemokine that is elevated in obesity and is linked to obesity-associated chronic diseases. Depletion of cholesterol by MβCD increased MCP-1 secretion as well as the mRNA and protein levels, suggesting perturbation at biosynthesis and secretion. Pharmacological inhibition revealed that NF-κB, but not MEK, p38 and JNK, was involved in MβCD-stimulated MCP-1 biosynthesis and secretion in adipocytes. Finally, another cholesterol-binding drug, filipin, also induced MCP-1 secretion without altering membrane cholesterol level. Interestingly, both MβCD and filipin disturbed the integrity of lipid rafts, the membrane microdomains enriched in cholesterol. Thus, the depletion of membrane cholesterol in obese adipocytes may result in dysfunction of lipid rafts, leading to the elevation of proinflammatory signaling and MCP-1 secretion in adipocytes.
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Affiliation(s)
- Juu-Chin Lu
- Department of Physiology and Pharmacology, Chang Gung University, Taoyuan, Taiwan
- Graduate Institute of Biomedical Sciences, Chang Gung University, Taoyuan, Taiwan
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Chang Gung Memorial Hospital, Linkou, Taiwan
- * E-mail:
| | - Yu-Ting Chiang
- Graduate Institute of Biomedical Sciences, Chang Gung University, Taoyuan, Taiwan
| | - Yu-Chun Lin
- Department of Physiology and Pharmacology, Chang Gung University, Taoyuan, Taiwan
- Graduate Institute of Biomedical Sciences, Chang Gung University, Taoyuan, Taiwan
| | - Yu-Tzu Chang
- Department of Physiology and Pharmacology, Chang Gung University, Taoyuan, Taiwan
| | - Chia-Yun Lu
- Department of Physiology and Pharmacology, Chang Gung University, Taoyuan, Taiwan
- Graduate Institute of Biomedical Sciences, Chang Gung University, Taoyuan, Taiwan
| | - Tzu-Yu Chen
- Department of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Chia-Shan Yeh
- Graduate Institute of Biomedical Sciences, Chang Gung University, Taoyuan, Taiwan
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Colin J, Gregory-Pauron L, Lanhers MC, Claudepierre T, Corbier C, Yen FT, Malaplate-Armand C, Oster T. Membrane raft domains and remodeling in aging brain. Biochimie 2016; 130:178-187. [DOI: 10.1016/j.biochi.2016.08.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 08/31/2016] [Indexed: 12/21/2022]
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Montenegro MF, Cabezas-Herrera J, Campoy FJ, Muñoz-Delgado E, Vidal CJ. Lipid rafts of mouse liver contain nonextended and extended acetylcholinesterase variants along with M3 muscarinic receptors. FASEB J 2016; 31:544-555. [PMID: 28148778 DOI: 10.1096/fj.201600609r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 10/11/2016] [Indexed: 12/25/2022]
Abstract
The observation of acetylcholinesterase (AChE) type H (AChEH), which is the predominant AChE variant in visceral organs and immune cells, in lipid rafts of muscle supports functional reasons for the raft targeting of glypiated AChEH The search for these reasons revealed that liver AChE activity is mostly confined to rafts and that the liver is able to make N-extended AChE variants and target them to rafts. These results prompted us to test whether AChE and muscarinic receptors existed in the same raft. Isolation of flotillin-2-rich raft fractions by their buoyancy in sucrose gradients, followed by immunoadsorption and matrix-assisted laser desorption ionization-time of flight-mass spectrometry application, gave the following results: 1) most hepatic AChE activity emanates from AChE-H mRNA, and its product, glypiated AChEH, accumulates in rafts; 2) N-extended N-AChE readthrough variant, nonglypiated N-AChEH, and N-AChE tailed variant were all identified in liver rafts; and 3) M3 AChRs were observed in rafts, and coprecipitation of raft-confined N-AChE and M3 receptors by using anti-M3 antibodies showed that enzyme and receptor reside in the same raft unit. A raft domain that harbors tightly packed muscarinic receptor and AChE may represent a molecular device that, by means of which, the intensity and duration of cholinergic inputs are regulated.-Montenegro, M. F., Cabezas-Herrera, J., Campoy, F. J., Muñoz-Delgado, E., Vidal, C. J. Lipid rafts of mouse liver contain nonextended and extended acetylcholinesterase variants along with M3 muscarinic receptors.
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Affiliation(s)
- María Fernanda Montenegro
- Departamento de Bioquímica y Biología Molecular-A, Instituto Murciano de Investigación Biosanitaria (IMIB), Universidad de Murcia, Regional Campus of International Excellence "Campus Mare Nostrum," Murcia, Spain; and
| | - Juan Cabezas-Herrera
- Molecular Therapy and Biomarkers Research Group, Clinical Analysis Service, University Hospital Virgen de la Arrixaca, IMIB-Arrixaca, Murcia, Spain
| | - F Javier Campoy
- Departamento de Bioquímica y Biología Molecular-A, Instituto Murciano de Investigación Biosanitaria (IMIB), Universidad de Murcia, Regional Campus of International Excellence "Campus Mare Nostrum," Murcia, Spain; and
| | - Encarnación Muñoz-Delgado
- Departamento de Bioquímica y Biología Molecular-A, Instituto Murciano de Investigación Biosanitaria (IMIB), Universidad de Murcia, Regional Campus of International Excellence "Campus Mare Nostrum," Murcia, Spain; and
| | - Cecilio J Vidal
- Departamento de Bioquímica y Biología Molecular-A, Instituto Murciano de Investigación Biosanitaria (IMIB), Universidad de Murcia, Regional Campus of International Excellence "Campus Mare Nostrum," Murcia, Spain; and
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Mendiola-Precoma J, Berumen LC, Padilla K, Garcia-Alcocer G. Therapies for Prevention and Treatment of Alzheimer's Disease. BIOMED RESEARCH INTERNATIONAL 2016; 2016:2589276. [PMID: 27547756 PMCID: PMC4980501 DOI: 10.1155/2016/2589276] [Citation(s) in RCA: 137] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 05/31/2016] [Accepted: 06/05/2016] [Indexed: 01/11/2023]
Abstract
Alzheimer's disease (AD) is the most common cause of dementia associated with a progressive neurodegenerative disorder, with a prevalence of 44 million people throughout the world in 2015, and this figure is estimated to double by 2050. This disease is characterized by blood-brain barrier disruption, oxidative stress, mitochondrial impairment, neuroinflammation, and hypometabolism; it is related to amyloid-β peptide accumulation and tau hyperphosphorylation as well as a decrease in acetylcholine levels and a reduction of cerebral blood flow. Obesity is a major risk factor for AD, because it induces adipokine dysregulation, which consists of the release of the proinflammatory adipokines and decreased anti-inflammatory adipokines, among other processes. The pharmacological treatments for AD can be divided into two categories: symptomatic treatments such as acetylcholinesterase inhibitors and N-methyl-D-aspartate (NMDA) receptor antagonists and etiology-based treatments such as secretase inhibitors, amyloid binders, and tau therapies. Strategies for prevention of AD through nonpharmacological treatments are associated with lifestyle interventions such as exercise, mental challenges, and socialization as well as caloric restriction and a healthy diet. AD is an important health issue on which all people should be informed so that prevention strategies that minimize the risk of its development may be implemented.
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Affiliation(s)
- J. Mendiola-Precoma
- Laboratorio de Investigación Genética, Facultad de Química, Universidad Autónoma de Querétaro, Cerro de las Campanas S/N, Centro Universitario, 76010 Santiago de Querétaro, QRO, Mexico
| | - L. C. Berumen
- Laboratorio de Investigación Genética, Facultad de Química, Universidad Autónoma de Querétaro, Cerro de las Campanas S/N, Centro Universitario, 76010 Santiago de Querétaro, QRO, Mexico
| | - K. Padilla
- Laboratorio de Investigación Genética, Facultad de Química, Universidad Autónoma de Querétaro, Cerro de las Campanas S/N, Centro Universitario, 76010 Santiago de Querétaro, QRO, Mexico
| | - G. Garcia-Alcocer
- Laboratorio de Investigación Genética, Facultad de Química, Universidad Autónoma de Querétaro, Cerro de las Campanas S/N, Centro Universitario, 76010 Santiago de Querétaro, QRO, Mexico
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18
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Ennis EA, Blakely RD. Choline on the Move: Perspectives on the Molecular Physiology and Pharmacology of the Presynaptic Choline Transporter. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2016; 76:175-213. [PMID: 27288078 DOI: 10.1016/bs.apha.2016.03.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Genetic, biochemical, physiological, and pharmacological approaches have advanced our understanding of cholinergic biology for over 100 years. High-affinity choline uptake (HACU) was one of the last features of cholinergic signaling to be defined at a molecular level, achieved through the cloning of the choline transporter (CHT, SLC5A7). In retrospect, the molecular era of CHT studies initiated with the identification of hemicholinium-3 (HC-3), a potent, competitive CHT antagonist, though it would take another 30 years before HC-3, in radiolabeled form, was used by Joseph Coyle's laboratory to identify and monitor the dynamics of CHT proteins. Though HC-3 studies provided important insights into CHT distribution and regulation, another 15 years would pass before the structure of CHT genes and proteins were identified, a full decade after the cloning of most other neurotransmitter-associated transporters. The availability of CHT gene and protein probes propelled the development of cell and animal models as well as efforts to gain insights into how human CHT gene variation affects the risk for brain and neuromuscular disorders. Most recently, our group has pursued a broadening of CHT pharmacology, elucidating novel chemical structures that may serve to advance cholinergic diagnostics and medication development. Here we provide a short review of the transformation that has occurred in HACU research and how such advances may promote the development of novel therapeutics.
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Affiliation(s)
- E A Ennis
- Vanderbilt University School of Medicine, Nashville, TN, United States
| | - R D Blakely
- Vanderbilt University School of Medicine, Nashville, TN, United States.
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Huang SS, Chen CL, Huang FW, Johnson FE, Huang JS. Ethanol Enhances TGF-β Activity by Recruiting TGF-β Receptors From Intracellular Vesicles/Lipid Rafts/Caveolae to Non-Lipid Raft Microdomains. J Cell Biochem 2015; 117:860-71. [PMID: 26419316 DOI: 10.1002/jcb.25389] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 09/28/2015] [Indexed: 12/16/2022]
Abstract
Regular consumption of moderate amounts of ethanol has important health benefits on atherosclerotic cardiovascular disease (ASCVD). Overindulgence can cause many diseases, particularly alcoholic liver disease (ALD). The mechanisms by which ethanol causes both beneficial and harmful effects on human health are poorly understood. Here we demonstrate that ethanol enhances TGF-β-stimulated luciferase activity with a maximum of 0.5-1% (v/v) in Mv1Lu cells stably expressing a luciferase reporter gene containing Smad2-dependent elements. In Mv1Lu cells, 0.5% ethanol increases the level of P-Smad2, a canonical TGF-β signaling sensor, by ∼ 2-3-fold. Ethanol (0.5%) increases cell-surface expression of the type II TGF-β receptor (TβR-II) by ∼ 2-3-fold from its intracellular pool, as determined by I(125) -TGF-β-cross-linking/Western blot analysis. Sucrose density gradient ultracentrifugation and indirect immunofluorescence staining analyses reveal that ethanol (0.5% and 1%) also displaces cell-surface TβR-I and TβR-II from lipid rafts/caveolae and facilitates translocation of these receptors to non-lipid raft microdomains where canonical signaling occurs. These results suggest that ethanol enhances canonical TGF-β signaling by increasing non-lipid raft microdomain localization of the TGF-β receptors. Since TGF-β plays a protective role in ASCVD but can also cause ALD, the TGF-β enhancer activity of ethanol at low and high doses appears to be responsible for both beneficial and harmful effects. Ethanol also disrupts the location of lipid raft/caveolae of other membrane proteins (e.g., neurotransmitter, growth factor/cytokine, and G protein-coupled receptors) which utilize lipid rafts/caveolae as signaling platforms. Displacement of these membrane proteins induced by ethanol may result in a variety of pathologies in nerve, heart and other tissues.
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Affiliation(s)
| | - Chun-Lin Chen
- Department of Biological Science, National Sun Yat-sen University, Kaohsiung, 804, Taiwan.,Doctoral Degree Program in Marine Biotechnology, National Sun Yat-sen University and Academia Sinica, Kaohsiung, 804, Taiwan
| | - Franklin W Huang
- Department of Medical Oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, 02115.,Harvard Medical School, Boston, Massachusetts, 02115
| | - Frank E Johnson
- Department of Surgery, Saint Louis University School of Medicine, St. Louis, Missouri, 63104
| | - Jung San Huang
- Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, Doisy Research Center, St. Louis, Missouri, 63104
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Insulin Regulates the Activity of the High-Affinity Choline Transporter CHT. PLoS One 2015; 10:e0132934. [PMID: 26161852 PMCID: PMC4498808 DOI: 10.1371/journal.pone.0132934] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Accepted: 06/21/2015] [Indexed: 12/22/2022] Open
Abstract
Studies in humans and animal models show that neuronal insulin resistance increases the risk of developing Alzheimer’s Disease (AD), and that insulin treatment may promote memory function. Cholinergic neurons play a critical role in cognitive and attentional processing and their dysfunction early in AD pathology may promote the progression of AD pathology. Synthesis and release of the neurotransmitter acetylcholine (ACh) is closely linked to the activity of the high-affinity choline transporter protein (CHT), but the impact of insulin receptor signaling and neuronal insulin resistance on these aspects of cholinergic function are unknown. In this study, we used differentiated SH-SY5Y cells stably-expressing CHT proteins to study the effect of insulin signaling on CHT activity and function. We find that choline uptake activity measured after acute addition of 20 nM insulin is significantly lower in cells that were grown for 24 h in media containing insulin compared to cells grown in the absence of insulin. This coincides with loss of ability to increase phospho-Protein Kinase B (PKB)/Akt levels in response to acute insulin stimulation in the chronic insulin-treated cells. Inhibition of phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3-kinase) in cells significantly lowers phospho-PKB/Akt levels and decreases choline uptake activity. We show total internal reflection microscopy (TIRF) imaging of the dynamic movement of CHT proteins in live cells in response to depolarization and drug treatments. These data show that acute exposure of depolarized cells to insulin is coupled to transiently increased levels of CHT proteins at the cell surface, and that this is attenuated by chronic insulin exposure. Moreover, prolonged inhibition of PI3-kinase results in enhanced levels of CHT proteins at the cell surface by decreasing their rate of internalization.
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Cuddy LK, Seah C, Pasternak SH, Rylett RJ. Differential regulation of the high-affinity choline transporter by wild-type and Swedish mutant amyloid precursor protein. J Neurochem 2015; 134:769-82. [DOI: 10.1111/jnc.13167] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2015] [Revised: 04/30/2015] [Accepted: 05/06/2015] [Indexed: 01/18/2023]
Affiliation(s)
- Leah K. Cuddy
- Molecular Medicine Research Group; Robarts Research Institute; London Ontario Canada
- Department of Physiology and Pharmacology; University of Western Ontario; London Ontario Canada
| | - Claudia Seah
- Molecular Medicine Research Group; Robarts Research Institute; London Ontario Canada
| | - Stephen H. Pasternak
- Molecular Medicine Research Group; Robarts Research Institute; London Ontario Canada
- Department of Physiology and Pharmacology; University of Western Ontario; London Ontario Canada
- Department of Clinical Neurological Sciences; Schulich School of Medicine & Dentistry; University of Western Ontario; London Ontario Canada
| | - Rebecca Jane Rylett
- Molecular Medicine Research Group; Robarts Research Institute; London Ontario Canada
- Department of Physiology and Pharmacology; University of Western Ontario; London Ontario Canada
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Michalec K, Mysiorek C, Kuntz M, Bérézowski V, Szczepankiewicz AA, Wilczyński GM, Cecchelli R, Nałęcz KA. Protein kinase C restricts transport of carnitine by amino acid transporter ATB(0,+) apically localized in the blood-brain barrier. Arch Biochem Biophys 2014; 554:28-35. [PMID: 24823859 DOI: 10.1016/j.abb.2014.05.006] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2014] [Revised: 04/29/2014] [Accepted: 05/03/2014] [Indexed: 10/25/2022]
Abstract
Carnitine (3-hydroxy-4-trimethylammoniobutyrate) is necessary for transfer of fatty acids through the inner mitochondrial membrane. Carnitine, not synthesized in the brain, is delivered there through the strongly polarized blood-brain barrier (BBB). Expression and presence of two carnitine transporters - organic cation/carnitine transporter (OCTN2) and amino acid transporter B(0,+) (ATB(0,+)) have been demonstrated previously in an in vitro model of the BBB. Due to potential protein kinase C (PKC) phosphorylation sites within ATB(0,+) sequence, the present study verified effects of this kinase on transporter function and localization in the BBB. ATB(0,+) can be regulated by estrogen receptor α and up-regulated in vitro, therefore its presence in vivo was verified with the transmission electron microscopy. The analyses of brain slices demonstrated ATB(0,+) luminal localization in brain capillaries, confirmed by biotinylation experiments in an in vitro model of the BBB. Brain capillary endothelial cells were shown to control carnitine gradient. ATB(0,+) was phosphorylated by PKC, what correlated with inhibition of carnitine transport. PKC activation did not change the amount of ATB(0,+) present in the apical membrane of brain endothelial cells, but resulted in transporter exclusion from raft microdomains. ATB(0,+) inactivation by a lateral movement in plasma membrane after transporter phosphorylation has been postulated.
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Affiliation(s)
- Katarzyna Michalec
- Laboratory of Mechanisms of Transport Through Biomembranes, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Caroline Mysiorek
- Univ Lille Nord de France, Lille, France; UArtois, LBHE, Lens, France; IMPRT-IFR114, Lille, France
| | - Mélanie Kuntz
- Univ Lille Nord de France, Lille, France; UArtois, LBHE, Lens, France; IMPRT-IFR114, Lille, France
| | - Vincent Bérézowski
- Univ Lille Nord de France, Lille, France; UArtois, LBHE, Lens, France; IMPRT-IFR114, Lille, France
| | - Andrzej A Szczepankiewicz
- Laboratory of Molecular and Systemic Neuromorphology, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Grzegorz M Wilczyński
- Laboratory of Molecular and Systemic Neuromorphology, Nencki Institute of Experimental Biology, Warsaw, Poland
| | - Roméo Cecchelli
- Univ Lille Nord de France, Lille, France; UArtois, LBHE, Lens, France; IMPRT-IFR114, Lille, France
| | - Katarzyna A Nałęcz
- Laboratory of Mechanisms of Transport Through Biomembranes, Nencki Institute of Experimental Biology, Warsaw, Poland.
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