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Shubhrasmita Sahu S, Sarkar P, Chattopadhyay A. Quantitation of F-actin in cytoskeletal reorganization: Context, methodology and implications. Methods 2024; 230:44-58. [PMID: 39074540 DOI: 10.1016/j.ymeth.2024.07.009] [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: 04/05/2024] [Revised: 07/08/2024] [Accepted: 07/17/2024] [Indexed: 07/31/2024] Open
Abstract
The actin cytoskeleton is involved in a large number of cellular signaling events in addition to providing structural integrity to the cell. Actin polymerization is a key event during cellular signaling. Although the role of actin cytoskeleton in cellular processes such as trafficking and motility has been extensively studied, the reorganization of the actin cytoskeleton upon signaling has been rarely explored due to lack of suitable assays. Keeping in mind this lacuna, we developed a confocal microscopy based approach that relies on high magnification imaging of cellular F-actin, followed by image reconstruction using commercially available software. In this review, we discuss the context and relevance of actin quantitation, followed by a detailed hands-on approach of the methodology involved with specific points on troubleshooting and useful precautions. In the latter part of the review, we elucidate the method by discussing applications of actin quantitation from our work in several important problems in contemporary membrane biology ranging from pathogen entry into host cells, to GPCR signaling and membrane-cytoskeleton interaction. We envision that future discovery of cell-permeable novel fluorescent probes, in combination with genetically encoded actin-binding reporters, would allow real-time visualization of actin cytoskeleton dynamics to gain deeper insights into active cellular processes in health and disease.
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Affiliation(s)
- Subhashree Shubhrasmita Sahu
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201 002, India
| | - Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India; Department of Biochemistry, Stanford University, School of Medicine, Stanford, CA 94305, USA
| | - Amitabha Chattopadhyay
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India; Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201 002, India.
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2
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Yuan WQ, Huang WP, Jiang YC, Xu H, Duan CS, Chen NH, Liu YJ, Fu XM. The function of astrocytes and their role in neurological diseases. Eur J Neurosci 2023; 58:3932-3961. [PMID: 37831013 DOI: 10.1111/ejn.16160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 09/11/2023] [Accepted: 09/13/2023] [Indexed: 10/14/2023]
Abstract
Astrocytes have countless links with neurons. Previously, astrocytes were only considered a scaffold of neurons; in fact, astrocytes perform a variety of functions, including providing support for neuronal structures and energy metabolism, offering isolation and protection and influencing the formation, function and elimination of synapses. Because of these functions, astrocytes play an critical role in central nervous system (CNS) diseases. The regulation of the secretiory factors, receptors, channels and pathways of astrocytes can effectively inhibit the occurrence and development of CNS diseases, such as neuromyelitis optica (NMO), multiple sclerosis, Alzheimer's disease (AD), Parkinson's disease (PD) and Huntington's disease. The expression of aquaporin 4 in AS is directly related to NMO and indirectly involved in the clearance of Aβ and tau proteins in AD. Connexin 43 has a bidirectional effect on glutamate diffusion at different stages of stroke. Interestingly, astrocytes reduce the occurrence of PD through multiple effects such as secretion of related factors, mitochondrial autophagy and aquaporin 4. Therefore, this review is focused on the structure and function of astrocytes and the correlation between astrocytes and CNS diseases and drug treatment to explore the new functions of astrocytes with the astrocytes as the target. This, in turn, would provide a reference for the development of new drugs to protect neurons and promote the recovery of nerve function.
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Affiliation(s)
- Wen-Qin Yuan
- College of Pharmacy, Jiangxi University of Chinese Medicine, Nanchang, China
| | - Wei-Peng Huang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica and Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
- College of Pharmacy, Minzu University of China, Beijing, China
| | - Yang-Chao Jiang
- College of Pharmacy, Jiangxi University of Chinese Medicine, Nanchang, China
| | - Hao Xu
- College of Economics and Management, Jiangxi University of Chinese Medicine, Nanchang, China
| | - Chong-Shen Duan
- College of Pharmacy, Jiangxi University of Chinese Medicine, Nanchang, China
| | - Nai-Hong Chen
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica and Neuroscience Center, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
| | - Ying-Jiao Liu
- College of Pharmacy, Jiangxi University of Chinese Medicine, Nanchang, China
| | - Xiao-Mei Fu
- College of Pharmacy, Jiangxi University of Chinese Medicine, Nanchang, China
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3
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Escoubas CC, Dorman LC, Nguyen PT, Lagares-Linares C, Nakajo H, Anderson SR, Cuevas B, Vainchtein ID, Silva NJ, Xiao Y, Lidsky PV, Wang EY, Taloma SE, Nakao-Inoue H, Schwer B, Andino R, Nowakowski TJ, Molofsky AV. Type I interferon responsive microglia shape cortical development and behavior. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2021.04.29.441889. [PMID: 35233577 PMCID: PMC8887080 DOI: 10.1101/2021.04.29.441889] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Microglia are brain resident phagocytes that can engulf synaptic components and extracellular matrix as well as whole neurons. However, whether there are unique molecular mechanisms that regulate these distinct phagocytic states is unknown. Here we define a molecularly distinct microglial subset whose function is to engulf neurons in the developing brain. We transcriptomically identified a cluster of Type I interferon (IFN-I) responsive microglia that expanded 20-fold in the postnatal day 5 somatosensory cortex after partial whisker deprivation, a stressor that accelerates neural circuit remodeling. In situ, IFN-I responsive microglia were highly phagocytic and actively engulfed whole neurons. Conditional deletion of IFN-I signaling (Ifnar1fl/fl) in microglia but not neurons resulted in dysmorphic microglia with stalled phagocytosis and an accumulation of neurons with double strand DNA breaks, a marker of cell stress. Conversely, exogenous IFN-I was sufficient to drive neuronal engulfment by microglia and restrict the accumulation of damaged neurons. IFN-I deficient mice had excess excitatory neurons in the developing somatosensory cortex as well as tactile hypersensitivity to whisker stimulation. These data define a molecular mechanism through which microglia engulf neurons during a critical window of brain development. More broadly, they reveal key homeostatic roles of a canonical antiviral signaling pathway in brain development.
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Affiliation(s)
- Caroline C. Escoubas
- Department of Psychiatry and Behavioral Sciences/ Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA
| | - Leah C. Dorman
- Department of Psychiatry and Behavioral Sciences/ Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA
- Department of Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA
| | - Phi T. Nguyen
- Department of Psychiatry and Behavioral Sciences/ Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA
- Department of Biomedical Sciences Graduate Program, University of California, San Francisco, San Francisco, CA
| | - Christian Lagares-Linares
- Department of Psychiatry and Behavioral Sciences/ Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA
| | - Haruna Nakajo
- Department of Psychiatry and Behavioral Sciences/ Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA
| | - Sarah R. Anderson
- Department of Psychiatry and Behavioral Sciences/ Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA
| | - Beatriz Cuevas
- Department of Psychiatry and Behavioral Sciences/ Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA
- Department of Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA
| | - Ilia D. Vainchtein
- Department of Psychiatry and Behavioral Sciences/ Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA
| | - Nicholas J. Silva
- Department of Psychiatry and Behavioral Sciences/ Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA
| | - Yinghong Xiao
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA
| | - Peter V. Lidsky
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA
| | - Ellen Y. Wang
- Department of Psychiatry and Behavioral Sciences/ Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA
- UCSF SRTP program, University of California, San Francisco, San Francisco, CA
| | - Sunrae E. Taloma
- Department of Psychiatry and Behavioral Sciences/ Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA
- Department of Neuroscience Graduate Program, University of California, San Francisco, San Francisco, CA
| | - Hiromi Nakao-Inoue
- Department of Psychiatry and Behavioral Sciences/ Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA
| | - Bjoern Schwer
- Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA
- Department of Neurosurgery, University of California, San Francisco, San Francisco, CA
| | - Raul Andino
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA
| | - Tomasz J. Nowakowski
- Department of Psychiatry and Behavioral Sciences/ Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA
- Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA
- Department of Anatomy, University of California, San Francisco, San Francisco, CA
- Eli and Edythe Broad Center for Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA
- Chan-Zuckerberg Biohub, San Francisco, CA
| | - Anna V. Molofsky
- Department of Psychiatry and Behavioral Sciences/ Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA
- Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, San Francisco, CA
- Eli and Edythe Broad Center for Regeneration Medicine and Stem Cell Research, University of California, San Francisco, San Francisco, CA
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Shrivastava S, Sarkar P, Preira P, Salomé L, Chattopadhyay A. Cholesterol-Dependent Dynamics of the Serotonin 1A Receptor Utilizing Single Particle Tracking: Analysis of Diffusion Modes. J Phys Chem B 2022; 126:6682-6690. [PMID: 35973070 DOI: 10.1021/acs.jpcb.2c03941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
G protein-coupled receptors (GPCRs) are signaling hubs in cell membranes that regulate a wide range of physiological processes and are popular drug targets. Serotonin1A receptors are important members of the GPCR family and are implicated in neuropsychiatric disorders. Cholesterol is a key constituent of higher eukaryotic membranes and is believed to contribute to the segregated distribution of membrane constituents into domains. To explore the role of cholesterol in lateral dynamics of GPCRs, we utilized single particle tracking (SPT) to monitor diffusion of serotonin1A receptors under acute and chronic cholesterol-depleted conditions. Our results show that the short-term diffusion coefficient of the receptor decreases upon cholesterol depletion, irrespective of the method of cholesterol depletion. Analysis of SPT trajectories revealed that relative populations of receptors undergoing various modes of diffusion change upon cholesterol depletion. Notably, in cholesterol-depleted cells, we observed an increase in the confined population of the receptor accompanied by a reduction in diffusion coefficient for chronic cholesterol depletion. These results are supported by our recent work and present observations that show polymerization of G-actin in response to chronic cholesterol depletion. Taken together, our results bring out the interdependence of cholesterol and actin cytoskeleton in regulating diffusion of GPCRs in membranes.
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Affiliation(s)
- Sandeep Shrivastava
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007, India
| | - Pascal Preira
- Institut de Pharmacologie et de Biologie Structurale, CNRS, Université de Toulouse (UPS), 31 077 Toulouse, France
| | - Laurence Salomé
- Institut de Pharmacologie et de Biologie Structurale, CNRS, Université de Toulouse (UPS), 31 077 Toulouse, France
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5
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Sarkar P, Kumar GA, Shrivastava S, Chattopadhyay A. Chronic cholesterol depletion increases F-actin levels and induces cytoskeletal reorganization via a dual mechanism. J Lipid Res 2022; 63:100206. [PMID: 35390404 PMCID: PMC9096963 DOI: 10.1016/j.jlr.2022.100206] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 03/22/2022] [Accepted: 03/28/2022] [Indexed: 12/24/2022] Open
Abstract
Previous work from us and others has suggested that cholesterol is an important lipid in the context of the organization of the actin cytoskeleton. However, reorganization of the actin cytoskeleton upon modulation of membrane cholesterol is rarely addressed in the literature. In this work, we explored the signaling crosstalk between cholesterol and the actin cytoskeleton by using a high-resolution confocal microscopic approach to quantitatively measure changes in F-actin content upon cholesterol depletion. Our results show that F-actin content significantly increases upon chronic cholesterol depletion, but not during acute cholesterol depletion. In addition, utilizing inhibitors targeting the cholesterol biosynthetic pathway at different steps, we show that reorganization of the actin cytoskeleton could occur due to the synergistic effect of multiple pathways, including prenylated Rho GTPases and availability of membrane phosphatidylinositol 4,5-bisphosphate. These results constitute one of the first comprehensive dissections of the mechanistic basis underlying the interplay between cellular actin levels and cholesterol biosynthesis. We envision these results will be relevant for future understating of the remodeling of the actin cytoskeleton in pathological conditions with altered cholesterol.
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Affiliation(s)
- Parijat Sarkar
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
| | - G Aditya Kumar
- CSIR-Centre for Cellular and Molecular Biology, Hyderabad, India
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6
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Dutta A, Mukku RP, Kumar GA, Jafurulla M, Raghunand TR, Chattopadhyay A. Integrity of the Actin Cytoskeleton of Host Macrophages is Necessary for Mycobacterial Entry. J Membr Biol 2022; 255:623-632. [PMID: 35166859 PMCID: PMC8852914 DOI: 10.1007/s00232-022-00217-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 01/27/2022] [Indexed: 11/16/2022]
Abstract
Macrophages are the primary hosts for Mycobacterium tuberculosis (M. tb), an intracellular pathogen, and the causative organism of tuberculosis (TB) in humans. While M. tb has the ability to enter and survive in host macrophages, the precise mechanism of its internalization, and factors that control this essential process are poorly defined. We have previously demonstrated that perturbations in levels of cholesterol and sphingolipids in macrophages lead to significant reduction in the entry of Mycobacterium smegmatis (M. smegmatis), a surrogate model for mycobacterial internalization, signifying a role for these plasma membrane lipids in interactions at the host–pathogen interface. In this work, we investigated the role of the host actin cytoskeleton, a critical protein framework underlying the plasma membrane, in the entry of M. smegmatis into human macrophages. Our results show that cytochalasin D mediated destabilization of the actin cytoskeleton of host macrophages results in a dose-dependent reduction in the entry of mycobacteria. Notably, the internalization of Escherichia coli remained invariant upon actin destabilization of host cells, implying a specific involvement of the actin cytoskeleton in mycobacterial infection. By monitoring the F-actin content of macrophages utilizing a quantitative confocal microscopy-based technique, we observed a close correlation between the entry of mycobacteria into host macrophages with cellular F-actin content. Our results constitute the first quantitative analysis of the role of the actin cytoskeleton of human macrophages in the entry of mycobacteria, and highlight actin-mediated mycobacterial entry as a potential target for future anti-TB therapeutics.
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Affiliation(s)
- Aritri Dutta
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500007, India
| | - Ravi Prasad Mukku
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500007, India
| | - G Aditya Kumar
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500007, India.,Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Md Jafurulla
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500007, India
| | - Tirumalai R Raghunand
- CSIR-Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad, 500007, India.
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7
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Roy S, Kumar GA, Jafurulla M, Mandal C, Chattopadhyay A. Integrity of the Actin Cytoskeleton of Host Macrophages is Essential for Leishmania donovani Infection. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:2011-8. [DOI: 10.1016/j.bbamem.2014.04.017] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2013] [Revised: 03/19/2014] [Accepted: 04/18/2014] [Indexed: 12/16/2022]
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8
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Sheean R, Lau C, Shin Y, O’Shea R, Beart P. Links between l-glutamate transporters, Na+/K+-ATPase and cytoskeleton in astrocytes: Evidence following inhibition with rottlerin. Neuroscience 2013; 254:335-46. [DOI: 10.1016/j.neuroscience.2013.09.043] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Revised: 09/20/2013] [Accepted: 09/21/2013] [Indexed: 02/06/2023]
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9
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Vandresen-Filho S, Martins WC, Bertoldo DB, Mancini G, Herculano BA, de Bem AF, Tasca CI. Atorvastatin prevents cell damage via modulation of oxidative stress, glutamate uptake and glutamine synthetase activity in hippocampal slices subjected to oxygen/glucose deprivation. Neurochem Int 2013; 62:948-55. [DOI: 10.1016/j.neuint.2013.03.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 02/28/2013] [Accepted: 03/03/2013] [Indexed: 10/27/2022]
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Krisanova N, Sivko R, Kasatkina L, Borisova T. Neuroprotection by lowering cholesterol: A decrease in membrane cholesterol content reduces transporter-mediated glutamate release from brain nerve terminals. Biochim Biophys Acta Mol Basis Dis 2012; 1822:1553-61. [DOI: 10.1016/j.bbadis.2012.06.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2012] [Revised: 05/22/2012] [Accepted: 06/11/2012] [Indexed: 01/05/2023]
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11
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Borisova T, Kasatkina L, Ostapchenko L. The proton gradient of secretory granules and glutamate transport in blood platelets during cholesterol depletion of the plasma membrane by methyl-β-cyclodextrin. Neurochem Int 2011; 59:965-75. [DOI: 10.1016/j.neuint.2011.07.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Revised: 07/07/2011] [Accepted: 07/11/2011] [Indexed: 10/17/2022]
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12
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Dong X, Xiao Y, Jiang X, Wang Y. Quantitative proteomic analysis revealed lovastatin-induced perturbation of cellular pathways in HL-60 cells. J Proteome Res 2011; 10:5463-71. [PMID: 21967149 DOI: 10.1021/pr200718p] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Lovastatin, a member of the statin family of drugs, is widely prescribed for treating hypercholesterolemia. The statin family of drugs, however, also shows promise for cancer treatment and prevention. Although lovastatin is known to be an inhibitor for HMG-CoA reductase, the precise mechanisms underlying the drug's antiproliferative activity remain unclearly defined. Here we utilized mass spectrometry, in conjunction with stable isotope labeling by amino acids in cell culture (SILAC), to analyze the perturbation of protein expression in HL-60 cells treated with lovastatin. We were able to quantify ∼3200 proteins with both forward and reverse SILAC labeling experiments, among which ∼120 exhibited significant alterations in expression levels upon lovastatin treatment. Apart from confirming the expected inhibition of the cholesterol biosynthesis pathway, our quantitative proteomic results revealed that lovastatin perturbed the estrogen receptor signaling pathway, which was manifested by the diminished expression of estrogen receptor α, steroid receptor RNA activator 1, and other related proteins. Lovastatin also altered glutamate metabolism through down-regulation of glutamine synthetase and γ-glutamylcysteine synthetase. Moreover, lovastatin treatment led to a marked down-regulation of carbonate dehydratase II (a.k.a. carbonic anhydrase II) and perturbed the protein ubiquitination pathway. Together, the results from the present study underscored several new cellular pathways perturbed by lovastatin.
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Affiliation(s)
- Xiaoli Dong
- Department of Chemistry, University of California, Riverside, California 92521-0403, United States
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13
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Seneff S, Wainwright G, Mascitelli L. Nutrition and Alzheimer's disease: the detrimental role of a high carbohydrate diet. Eur J Intern Med 2011; 22:134-40. [PMID: 21402242 DOI: 10.1016/j.ejim.2010.12.017] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Revised: 12/08/2010] [Accepted: 12/27/2010] [Indexed: 01/13/2023]
Abstract
Alzheimer's disease is a devastating disease whose recent increase in incidence rates has broad implications for rising health care costs. Huge amounts of research money are currently being invested in seeking the underlying cause, with corresponding progress in understanding the disease progression. In this paper, we highlight how an excess of dietary carbohydrates, particularly fructose, alongside a relative deficiency in dietary fats and cholesterol, may lead to the development of Alzheimer's disease. A first step in the pathophysiology of the disease is represented by advanced glycation end-products in crucial plasma proteins concerned with fat, cholesterol, and oxygen transport. This leads to cholesterol deficiency in neurons, which significantly impairs their ability to function. Over time, a cascade response leads to impaired glutamate signaling, increased oxidative damage, mitochondrial and lysosomal dysfunction, increased risk to microbial infection, and, ultimately, apoptosis. Other neurodegenerative diseases share many properties with Alzheimer's disease, and may also be due in large part to this same underlying cause.
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Affiliation(s)
- Stephanie Seneff
- Department of Electrical Engineering and Computer Science, MIT Cambridge, MA, USA
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De Conto F, Covan S, Arcangeletti MC, Orlandini G, Gatti R, Dettori G, Chezzi C. Differential infectious entry of human influenza A/NWS/33 virus (H1N1) in mammalian kidney cells. Virus Res 2010; 155:221-30. [PMID: 20951747 DOI: 10.1016/j.virusres.2010.10.008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2010] [Revised: 10/07/2010] [Accepted: 10/07/2010] [Indexed: 02/04/2023]
Abstract
In this report we focused our interest on the early events of the replication cycle of NWS/33 human influenza A (NWS) virus in MDCK (canine), LLC-MK2 (simian), and NSK (swine) kidney cells, with different susceptibility upon infection. We have previously demonstrated that actin organization induces restriction to viral replication during the early stages of NWS virus infection in simian kidney cells. To explore how cell endocytic mechanisms are hijacked by NWS virus and may modulate the outcome of viral infection, the effect of drugs affecting selectively the entry via clathrin-coated pits, caveolar/raft-dependent endocytosis and macropinocytosis was analyzed. Results point to critical differences in terms of internalization pathways exploited by NWS virus to enter the examined cell models. Moreover, we show that some ways of entry do not allow an effective virus internalization, depending on the cell type. Understanding how specific cell functions/components may regulate early phases of viral replication allows us to deepen our knowledge on influenza virus infection and provides new insights for anti-viral researches.
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Affiliation(s)
- Flora De Conto
- Microbiology Section, Department of Pathology and Laboratory Medicine, University of Parma, Parma, Italy.
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15
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Ganguly S, Chattopadhyay A. Cholesterol depletion mimics the effect of cytoskeletal destabilization on membrane dynamics of the serotonin1A receptor: A zFCS study. Biophys J 2010; 99:1397-407. [PMID: 20816051 PMCID: PMC2931730 DOI: 10.1016/j.bpj.2010.06.031] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2010] [Revised: 06/14/2010] [Accepted: 06/15/2010] [Indexed: 01/23/2023] Open
Abstract
Single-point fluorescence correlation spectroscopy (FCS) of membrane-bound molecules suffers from a number of limitations leading to inaccurate estimation of diffusion parameters. To overcome such problems and with the overall goal of addressing membrane heterogeneities, we performed z-scan FCS (zFCS) of the serotonin(1A) receptor. We analyzed the results according to FCS diffusion laws that provide information on the organization of the diffusing species. Analysis of our results shows that the diffusion coefficients of the receptor and a fluorescently labeled phospholipid are similar when probed at length scales approximately 210 nm. We discuss the significance of the spatiotemporal evolution of dynamics of membrane-bound molecules in the overall context of membrane domains and heterogeneity. Importantly, our results show that the serotonin(1A) receptor exhibits confinement in cell membranes, possibly due to interaction with the actin cytoskeleton. Surprisingly, depletion of membrane cholesterol appears to reduce receptor confinement in a manner similar to that observed in the case of cytoskeletal destabilization, implying possible changes in the actin cytoskeleton induced upon cholesterol depletion. These results constitute the first report on G-protein-coupled receptor dynamics utilizing a combination of zFCS and the FCS diffusion laws, and present a convenient approach to explore cell membrane heterogeneity at the submicron level.
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Affiliation(s)
| | - Amitabha Chattopadhyay
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Hyderabad, India
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16
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Diverse Presynaptic Mechanisms Underlying Methyl-β-Cyclodextrin-Mediated Changes in Glutamate Transport. Cell Mol Neurobiol 2010; 30:1013-23. [DOI: 10.1007/s10571-010-9532-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2009] [Accepted: 05/13/2010] [Indexed: 02/05/2023]
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17
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Borisova T, Krisanova N, Sivko R, Borysov A. Cholesterol depletion attenuates tonic release but increases the ambient level of glutamate in rat brain synaptosomes. Neurochem Int 2010; 56:466-78. [DOI: 10.1016/j.neuint.2009.12.006] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2009] [Revised: 12/07/2009] [Accepted: 12/11/2009] [Indexed: 10/20/2022]
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18
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Dong W, Vuletic S, Albers JJ. Differential effects of simvastatin and pravastatin on expression of Alzheimer's disease-related genes in human astrocytes and neuronal cells. J Lipid Res 2009; 50:2095-102. [PMID: 19461118 PMCID: PMC2739764 DOI: 10.1194/jlr.m900236-jlr200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2009] [Indexed: 11/20/2022] Open
Abstract
Inhibitors of HMG-CoA reductase (statins) are widely used medications for reduction of cholesterol levels. Statin use significantly reduces risk of cardiovascular disease but has also been associated with lower risk of other diseases and conditions, including dementia. However, some reports suggest that statins also have detrimental effects on the brain. We provide evidence that simvastatin and pravastatin have significantly different effects on expression of genes related to neurodegeneration in astrocytes and neuroblastoma (SK-N-SH) cells in culture. Simvastatin significantly reduced expression of ABCA1 in astrocytes and neuroblastoma cells (by 79% and 97%, respectively; both P < 0.001). Pravastatin had a similar but attenuated effect on ABCA1 in astrocytes (-54%, P < 0.001) and neuroblastoma cells (-70%, P < 0.001). Simvastatin reduced expression of apolipoprotein E in astrocytes (P < 0.01). Furthermore, both statins reduced expression of microtubule-associated protein tau in astrocytes (P < 0.01), while both statins increased its expression in neuroblastoma cells (P < 0.01). In SK-N-SH cells, simvastatin significantly increased cyclin-dependent kinase 5 and glycogen synthase kinase 3beta expression, while pravastatin increased amyloid precursor protein expression. Our data suggest that simvastatin and pravastatin differentially affect expression of genes involved in neurodegeneration and that statin-dependent gene expression regulation is cell type specific.
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Affiliation(s)
- Weijiang Dong
- Northwest Lipid Metabolism and Diabetes Research Laboratories, University of Washington, Department of Medicine, Seattle 98109, WA
- Xi’an Jiaotong University School of Medicine, Department of Human Anatomy and Histology and Embryology, Xi’an 710061, People’s Republic of China
| | - Simona Vuletic
- Northwest Lipid Metabolism and Diabetes Research Laboratories, University of Washington, Department of Medicine, Seattle 98109, WA
| | - John J. Albers
- Northwest Lipid Metabolism and Diabetes Research Laboratories, University of Washington, Department of Medicine, Seattle 98109, WA
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Ponce J, de la Ossa NP, Hurtado O, Millan M, Arenillas JF, Dávalos A, Gasull T. Simvastatin reduces the association of NMDA receptors to lipid rafts: a cholesterol-mediated effect in neuroprotection. Stroke 2008; 39:1269-75. [PMID: 18323503 DOI: 10.1161/strokeaha.107.498923] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
BACKGROUND AND PURPOSE Excess brain extracellular glutamate induced by cerebral ischemia leads to neuronal death, mainly through overactivation of N-methyl-D-aspartate (NMDA) receptors. The cholesterol-lowering drugs statins have been reported to protect from NMDA-induced neuronal death but, so far, the mechanism underlying this protection remains unclear. Because NMDA receptors have been reported to be associated with the cholesterol-rich membrane domains known as lipid rafts, we have investigated the effect of treatments that deplete cholesterol levels on excitotoxicity and on association of NMDA receptors to lipid rafts. METHODS Primary neuronal cultures were pretreated with inhibitors of cholesterol synthesis and cholesterol, and NMDA-induced cell death was determined by measuring release of lactate dehydrogenase. Lipid raft fractions were isolated and Western blots were performed. RESULTS Treatment with the inhibitors of cholesterol synthesis simvastatin, which inhibits the first step of cholesterol synthesis, or AY9944, which inhibits the last step of cholesterol synthesis, protected neurons from NMDA-induced neuronal death by 70% and 54%, respectively. Treatment with these compounds reduced neuronal cholesterol levels by 35% and 13%, respectively. Simvastatin and AY9944 reduced the association of the subunit 1 of NMDA receptors (NMDAR1) to lipid rafts by 42% and 21%, respectively, and did not change total expression of NMDAR1. Addition of cholesterol reduced neuroprotection by statins and AY9944, and partially reverted the effect of simvastatin on the association of NMDAR1 to lipid rafts. CONCLUSIONS These data demonstrate that reduction of cholesterol levels protects from NMDA-induced neuronal damage probably by reducing the association of NMDA receptors to lipid rafts.
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Affiliation(s)
- Jovita Ponce
- Neuroscience Basic Research Lab, Fundació Institut d'Investigació en Ciències de Salut Germans Trias i Pujol, Badalona, Spain
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Liver X receptor beta (LXRbeta): a link between beta-sitosterol and amyotrophic lateral sclerosis-Parkinson's dementia. Proc Natl Acad Sci U S A 2008; 105:2094-9. [PMID: 18238900 DOI: 10.1073/pnas.0711599105] [Citation(s) in RCA: 107] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Administration of beta-sitosterol (42 mg/kg per day) for 3 weeks to 8-month-old male LXRbeta-/- mice resulted in the death of motor neurons in the lumbar region of the spinal cord and loss of tyrosine hydroxylase-positive dopaminergic neurons in the substantia nigra. In mice at 5 months of age, beta-sitosterol had no observed toxicity but at 16 months of age, it caused severe paralysis and symptoms typical of dopaminergic dysfunction in LXRbeta-/- mice. WT mice were not affected by these doses of beta-sitosterol. In 5-month-old mice, levels of the intestinal transporters, ABCG5/8 and Niemann-Pick C1 Like 1, were not affected by loss of liver X receptor (LXR) beta and/or treatment with beta-sitosterol nor were there changes in plasma levels of cholesterol or beta-sitosterol. In 8-month-old LXRbeta-/- mice there was activation of microglia in the substantia nigra pars reticulata and aggregates of ubiquitin and TDP-43 in the cytoplasm of large motor neurons in the lumbar spinal cord. Brain cholesterol concentrations were higher in LXRbeta-/- than in their WT counterparts, and treatment with beta-sitosterol reduced brain cholesterol in both WT and LXRbeta-/- mice. In LXRbeta-/- mice but not in WT mice levels of 24-hydrocholesterol were increased upon beta-sitosterol treatment. These data indicate that multiple mechanisms are involved in the sensitivity of LXRbeta-/- mice to beta-sitosterol. These include activation of microglia, accumulation of protein aggregates in the cytoplasm of large motor neurons, and depletion of brain cholesterol.
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