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Macdonald Miller S, Abbriano RM, Herdean A, Banati R, Ralph PJ, Pernice M. Random mutagenesis of Phaeodactylum tricornutum using ultraviolet, chemical, and X-radiation demonstrates the need for temporal analysis of phenotype stability. Sci Rep 2023; 13:22385. [PMID: 38104215 PMCID: PMC10725415 DOI: 10.1038/s41598-023-45899-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 10/25/2023] [Indexed: 12/19/2023] Open
Abstract
We investigated two non-ionising mutagens in the form of ultraviolet radiation (UV) and ethyl methanosulfonate (EMS) and an ionising mutagen (X-ray) as methods to increase fucoxanthin content in the model diatom Phaeodactylum tricornutum. We implemented an ultra-high throughput method using fluorescence-activated cell sorting (FACS) and live culture spectral deconvolution for isolation and screening of potential pigment mutants, and assessed phenotype stability by measuring pigment content over 6 months using high-performance liquid chromatography (HPLC) to investigate the viability of long-term mutants. Both UV and EMS resulted in significantly higher fucoxanthin within the 6 month period after treatment, likely as a result of phenotype instability. A maximum fucoxanthin content of 135 ± 10% wild-type found in the EMS strain, a 35% increase. We found mutants generated using all methods underwent reversion to the wild-type phenotype within a 6 month time period. X-ray treatments produced a consistently unstable phenotype even at the maximum treatment of 1000 Grays, while a UV mutant and an EMS mutant reverted to wild-type after 4 months and 6 months, respectively, despite showing previously higher fucoxanthin than wild-type. This work provides new insights into key areas of microalgal biotechnology, by (i) demonstrating the use of an ionising mutagen (X-ray) on a biotechnologically relevant microalga, and by (ii) introducing temporal analysis of mutants which has substantial implications for strain creation and utility for industrial applications.
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Affiliation(s)
- Sean Macdonald Miller
- Faculty of Science, Climate Change Cluster (C3), University of Technology Sydney, Sydney, NSW, 2007, Australia.
| | - Raffaela M Abbriano
- Faculty of Science, Climate Change Cluster (C3), University of Technology Sydney, Sydney, NSW, 2007, Australia
| | - Andrei Herdean
- Faculty of Science, Climate Change Cluster (C3), University of Technology Sydney, Sydney, NSW, 2007, Australia
| | - Richard Banati
- Australian Nuclear Science and Technology Organisation (ANSTO), Kirrawee DC, NSW, 2232, Australia
- Faculty of Medicine and Health, University of Sydney, Camperdown, NSW, 2006, Australia
| | - Peter J Ralph
- Faculty of Science, Climate Change Cluster (C3), University of Technology Sydney, Sydney, NSW, 2007, Australia
| | - Mathieu Pernice
- Faculty of Science, Climate Change Cluster (C3), University of Technology Sydney, Sydney, NSW, 2007, Australia
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2
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Westerhausen MT, Bernard M, Choi G, Jeffries-Stokes C, Chandrajith R, Banati R, Bishop DP. Preparation of matrix-matched standards for the analysis of teeth via laser ablation-inductively coupled plasma-mass spectrometry. Anal Methods 2023; 15:797-806. [PMID: 36722471 DOI: 10.1039/d2ay02015g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Mineralised tissue such as teeth can serve as a retrospective, chronological bioindicator of past exposure to toxic metals. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) can be used to determine the presence and spatial distribution of toxic metals in teeth, giving a record of when an exposure occurred. Concentrations of these metals are often determined by a one-point calibration against NIST glass using an equation that requires an internal standard factor that accounts for differences in ablation behaviour between the glass and the tooth. However, an ideal external calibration would contain multiple matrix-matched standards to obtain a calibration curve. Here, we investigated optimal procedures for preparing synthetic hydroxyapatite (HA) doped with elements of interest as a calibration material. The materials were examined for homogeneity of metal incorporation, matrix-matched ablation characteristics, linearity, and limits of detection. A homogenised and pelleted HA was the most suitable material, providing improved ablation characteristics over previous HA materials and NIST glass for the analysis of teeth. An ablation yield of 1.1 showed its suitability to analyse teeth, the metals were homogeneously incorporated, and it produced excellent linearity with limits of detection ranging from 0.1-2 μg kg-1 for magnesium, aluminium, nickel, copper, zinc, cadmium, barium and lead. A juvenile incisor from a remote indigenous community in Australia and an adult molar from Sri Lanka were assessed for toxic metal exposure. The molar showed evidence of exposure to cadmium and lead. The synthetic HA material was straightforward to prepare, and will improve confidence in the analysis of teeth and other biomineralised material when assessing toxic metal exposure.
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Affiliation(s)
- Mika T Westerhausen
- Hyphenated Mass Spectrometry Laboratory (HyMaS), School of Mathematical and Physical Sciences, Faculty of Science, University of Technology Sydney, P. O. Box 123, Broadway, NSW 2007, Australia.
| | - Martin Bernard
- Hyphenated Mass Spectrometry Laboratory (HyMaS), School of Mathematical and Physical Sciences, Faculty of Science, University of Technology Sydney, P. O. Box 123, Broadway, NSW 2007, Australia.
| | - Gina Choi
- Hyphenated Mass Spectrometry Laboratory (HyMaS), School of Mathematical and Physical Sciences, Faculty of Science, University of Technology Sydney, P. O. Box 123, Broadway, NSW 2007, Australia.
| | | | - Rohana Chandrajith
- Department of Geology, Faculty of Science, University of Peradeniya, Peradeniya, Sri Lanka
| | - Richard Banati
- Australian Nuclear Science and Technology Organisation, New Illawarra Rd, Lucas Heights, NSW 2234, Australia
- Faculty of Medicine and Health, University of Sydney, 94 Mallett St, Camperdown, NSW 2050, Australia
| | - David P Bishop
- Hyphenated Mass Spectrometry Laboratory (HyMaS), School of Mathematical and Physical Sciences, Faculty of Science, University of Technology Sydney, P. O. Box 123, Broadway, NSW 2007, Australia.
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Betlazar C, Middleton RJ, Howell N, Storer B, Davis E, Davies J, Banati R, Liu GJ. Mitochondrial Translocator Protein (TSPO) Expression in the Brain After Whole Body Gamma Irradiation. Front Cell Dev Biol 2021; 9:715444. [PMID: 34760884 PMCID: PMC8573390 DOI: 10.3389/fcell.2021.715444] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 09/29/2021] [Indexed: 01/04/2023] Open
Abstract
The brain’s early response to low dose ionizing radiation, as may be encountered during diagnostic procedures and space exploration, is not yet fully characterized. In the brain parenchyma, the mitochondrial translocator protein (TSPO) is constitutively expressed at low levels by endothelial cells, and can therefore be used to assess the integrity of the brain’s vasculature. At the same time, the inducible expression of TSPO in activated microglia, the brain’s intrinsic immune cells, is a regularly observed early indicator of subtle or incipient brain pathology. Here, we explored the use of TSPO as a biomarker of brain tissue injury following whole body irradiation. Post-radiation responses were measured in C57BL/6 wild type (Tspo+/+) and TSPO knockout (Tspo–/–) mice 48 h after single whole body gamma irradiations with low doses 0, 0.01, and 0.1 Gy and a high dose of 2 Gy. Additionally, post-radiation responses of primary microglial cell cultures were measured at 1, 4, 24, and 48 h at an irradiation dose range of 0 Gy-2 Gy. TSPO mRNA and protein expression in the brain showed a decreased trend after 0.01 Gy relative to sham-irradiated controls, but remained unchanged after higher doses. Immunohistochemistry confirmed subtle decreases in TSPO expression after 0.01 Gy in vascular endothelial cells of the hippocampal region and in ependymal cells, with no detectable changes following higher doses. Cytokine concentrations in plasma after whole body irradiation showed differential changes in IL-6 and IL-10 with some variations between Tspo–/– and Tspo+/+ animals. The in vitro measurements of TSPO in primary microglial cell cultures showed a significant reduction 1 h after low dose irradiation (0.01 Gy). In summary, acute low and high doses of gamma irradiation up to 2 Gy reduced TSPO expression in the brain’s vascular compartment without de novo induction of TSPO expression in parenchymal microglia, while TSPO expression in directly irradiated, isolated, and thus highly activated microglia, too, was reduced after low dose irradiation. The potential link between TSPO, its role in mitochondrial energy metabolism and the selective radiation sensitivity, notably of cells with constitutive TSPO expression such as vascular endothelial cells, merits further exploration.
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Affiliation(s)
- Calina Betlazar
- Australian Nuclear Science and Technology Organisation, Sydney, NSW, Australia.,Discipline of Medical Imaging and Radiation Sciences, Faculty of Medicine and Health, Brain and Mind Centre, University of Sydney, Camperdown, NSW, Australia
| | - Ryan J Middleton
- Australian Nuclear Science and Technology Organisation, Sydney, NSW, Australia
| | - Nicholas Howell
- Australian Nuclear Science and Technology Organisation, Sydney, NSW, Australia
| | - Ben Storer
- Australian Nuclear Science and Technology Organisation, Sydney, NSW, Australia
| | - Emma Davis
- Australian Nuclear Science and Technology Organisation, Sydney, NSW, Australia
| | - Justin Davies
- Australian Nuclear Science and Technology Organisation, Sydney, NSW, Australia
| | - Richard Banati
- Australian Nuclear Science and Technology Organisation, Sydney, NSW, Australia.,Discipline of Medical Imaging and Radiation Sciences, Faculty of Medicine and Health, Brain and Mind Centre, University of Sydney, Camperdown, NSW, Australia
| | - Guo-Jun Liu
- Australian Nuclear Science and Technology Organisation, Sydney, NSW, Australia.,Discipline of Medical Imaging and Radiation Sciences, Faculty of Medicine and Health, Brain and Mind Centre, University of Sydney, Camperdown, NSW, Australia
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Meikle SR, Sossi V, Roncali E, Cherry SR, Banati R, Mankoff D, Jones T, James M, Sutcliffe J, Ouyang J, Petibon Y, Ma C, El Fakhri G, Surti S, Karp JS, Badawi RD, Yamaya T, Akamatsu G, Schramm G, Rezaei A, Nuyts J, Fulton R, Kyme A, Lois C, Sari H, Price J, Boellaard R, Jeraj R, Bailey DL, Eslick E, Willowson KP, Dutta J. Quantitative PET in the 2020s: a roadmap. Phys Med Biol 2021; 66:06RM01. [PMID: 33339012 PMCID: PMC9358699 DOI: 10.1088/1361-6560/abd4f7] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Positron emission tomography (PET) plays an increasingly important role in research and clinical applications, catalysed by remarkable technical advances and a growing appreciation of the need for reliable, sensitive biomarkers of human function in health and disease. Over the last 30 years, a large amount of the physics and engineering effort in PET has been motivated by the dominant clinical application during that period, oncology. This has led to important developments such as PET/CT, whole-body PET, 3D PET, accelerated statistical image reconstruction, and time-of-flight PET. Despite impressive improvements in image quality as a result of these advances, the emphasis on static, semi-quantitative 'hot spot' imaging for oncologic applications has meant that the capability of PET to quantify biologically relevant parameters based on tracer kinetics has not been fully exploited. More recent advances, such as PET/MR and total-body PET, have opened up the ability to address a vast range of new research questions, from which a future expansion of applications and radiotracers appears highly likely. Many of these new applications and tracers will, at least initially, require quantitative analyses that more fully exploit the exquisite sensitivity of PET and the tracer principle on which it is based. It is also expected that they will require more sophisticated quantitative analysis methods than those that are currently available. At the same time, artificial intelligence is revolutionizing data analysis and impacting the relationship between the statistical quality of the acquired data and the information we can extract from the data. In this roadmap, leaders of the key sub-disciplines of the field identify the challenges and opportunities to be addressed over the next ten years that will enable PET to realise its full quantitative potential, initially in research laboratories and, ultimately, in clinical practice.
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Affiliation(s)
- Steven R Meikle
- Sydney School of Health Sciences, Faculty of Medicine and Health, The University of Sydney, Australia
- Brain and Mind Centre, The University of Sydney, Australia
| | - Vesna Sossi
- Department of Physics and Astronomy, University of British Columbia, Canada
| | - Emilie Roncali
- Department of Biomedical Engineering, University of California, Davis, United States of America
| | - Simon R Cherry
- Department of Biomedical Engineering, University of California, Davis, United States of America
- Department of Radiology, University of California, Davis, United States of America
| | - Richard Banati
- Sydney School of Health Sciences, Faculty of Medicine and Health, The University of Sydney, Australia
- Brain and Mind Centre, The University of Sydney, Australia
- Australian Nuclear Science and Technology Organisation, Sydney, Australia
| | - David Mankoff
- Department of Radiology, University of Pennsylvania, United States of America
| | - Terry Jones
- Department of Radiology, University of California, Davis, United States of America
| | - Michelle James
- Department of Radiology, Molecular Imaging Program at Stanford (MIPS), CA, United States of America
- Department of Neurology and Neurological Sciences, Stanford University, CA, United States of America
| | - Julie Sutcliffe
- Department of Biomedical Engineering, University of California, Davis, United States of America
- Department of Internal Medicine, University of California, Davis, CA, United States of America
| | - Jinsong Ouyang
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, United States of America
| | - Yoann Petibon
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, United States of America
| | - Chao Ma
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, United States of America
| | - Georges El Fakhri
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, United States of America
| | - Suleman Surti
- Department of Radiology, University of Pennsylvania, United States of America
| | - Joel S Karp
- Department of Radiology, University of Pennsylvania, United States of America
| | - Ramsey D Badawi
- Department of Biomedical Engineering, University of California, Davis, United States of America
- Department of Radiology, University of California, Davis, United States of America
| | - Taiga Yamaya
- National Institute of Radiological Sciences (NIRS), National Institutes for Quantum and Radiological Science and Technology (QST), Chiba, Japan
| | - Go Akamatsu
- National Institute of Radiological Sciences (NIRS), National Institutes for Quantum and Radiological Science and Technology (QST), Chiba, Japan
| | - Georg Schramm
- Department of Imaging and Pathology, Nuclear Medicine & Molecular imaging, KU Leuven, Belgium
| | - Ahmadreza Rezaei
- Department of Imaging and Pathology, Nuclear Medicine & Molecular imaging, KU Leuven, Belgium
| | - Johan Nuyts
- Department of Imaging and Pathology, Nuclear Medicine & Molecular imaging, KU Leuven, Belgium
| | - Roger Fulton
- Brain and Mind Centre, The University of Sydney, Australia
- Department of Medical Physics, Westmead Hospital, Sydney, Australia
| | - André Kyme
- Brain and Mind Centre, The University of Sydney, Australia
- School of Biomedical Engineering, Faculty of Engineering and IT, The University of Sydney, Australia
| | - Cristina Lois
- Gordon Center for Medical Imaging, Massachusetts General Hospital and Harvard Medical School, United States of America
| | - Hasan Sari
- Department of Radiology, Massachusetts General Hospital & Harvard Medical School, Boston, MA, United States of America
- Athinoula A. Martinos Center, Massachusetts General Hospital & Harvard Medical School, Boston, MA, United States of America
| | - Julie Price
- Department of Radiology, Massachusetts General Hospital & Harvard Medical School, Boston, MA, United States of America
- Athinoula A. Martinos Center, Massachusetts General Hospital & Harvard Medical School, Boston, MA, United States of America
| | - Ronald Boellaard
- Radiology and Nuclear Medicine, Cancer Center Amsterdam, Amsterdam University Medical Center, location VUMC, Netherlands
| | - Robert Jeraj
- Departments of Medical Physics, Human Oncology and Radiology, University of Wisconsin, United States of America
- Faculty of Mathematics and Physics, University of Ljubljana, Slovenia
| | - Dale L Bailey
- Sydney School of Health Sciences, Faculty of Medicine and Health, The University of Sydney, Australia
- Department of Nuclear Medicine, Royal North Shore Hospital, Sydney, Australia
- Faculty of Science, The University of Sydney, Australia
| | - Enid Eslick
- Department of Nuclear Medicine, Royal North Shore Hospital, Sydney, Australia
| | - Kathy P Willowson
- Department of Nuclear Medicine, Royal North Shore Hospital, Sydney, Australia
- Faculty of Science, The University of Sydney, Australia
| | - Joyita Dutta
- Department of Electrical and Computer Engineering, University of Massachusetts Lowell, United States of America
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5
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Bao G, Wang X, Xu R, Loh C, Adeyinka OD, Pieris DA, Cherepanoff S, Gracie G, Lee M, McDonald KL, Nowak AK, Banati R, Buckland ME, Graeber MB. PathoFusion: An Open-Source AI Framework for Recognition of Pathomorphological Features and Mapping of Immunohistochemical Data. Cancers (Basel) 2021; 13:617. [PMID: 33557152 PMCID: PMC7913958 DOI: 10.3390/cancers13040617] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2020] [Revised: 11/25/2020] [Accepted: 01/29/2021] [Indexed: 12/03/2022] Open
Abstract
We have developed a platform, termed PathoFusion, which is an integrated system for marking, training, and recognition of pathological features in whole-slide tissue sections. The platform uses a bifocal convolutional neural network (BCNN) which is designed to simultaneously capture both index and contextual feature information from shorter and longer image tiles, respectively. This is analogous to how a microscopist in pathology works, identifying a cancerous morphological feature in the tissue context using first a narrow and then a wider focus, hence bifocal. Adjacent tissue sections obtained from glioblastoma cases were processed for hematoxylin and eosin (H&E) and immunohistochemical (CD276) staining. Image tiles cropped from the digitized images based on markings made by a consultant neuropathologist were used to train the BCNN. PathoFusion demonstrated its ability to recognize malignant neuropathological features autonomously and map immunohistochemical data simultaneously. Our experiments show that PathoFusion achieved areas under the curve (AUCs) of 0.985 ± 0.011 and 0.988 ± 0.001 in patch-level recognition of six typical pathomorphological features and detection of associated immunoreactivity, respectively. On this basis, the system further correlated CD276 immunoreactivity to abnormal tumor vasculature. Corresponding feature distributions and overlaps were visualized by heatmaps, permitting high-resolution qualitative as well as quantitative morphological analyses for entire histological slides. Recognition of more user-defined pathomorphological features can be added to the system and included in future tissue analyses. Integration of PathoFusion with the day-to-day service workflow of a (neuro)pathology department is a goal. The software code for PathoFusion is made publicly available.
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Affiliation(s)
- Guoqing Bao
- School of Computer Science, The University of Sydney, J12/1 Cleveland St, Darlington, Sydney, NSW 2008, Australia;
| | - Xiuying Wang
- School of Computer Science, The University of Sydney, J12/1 Cleveland St, Darlington, Sydney, NSW 2008, Australia;
| | - Ran Xu
- Ken Parker Brain Tumour Research Laboratories, Brain and Mind Centre, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2006, Australia; (R.X.); (C.L.); (O.D.A.); (D.A.P.)
- Department of Neurosurgery, Xuanwu Hospital, Capital Medical University, No. 45 Changchun Street, Beijing 100053, China
| | - Christina Loh
- Ken Parker Brain Tumour Research Laboratories, Brain and Mind Centre, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2006, Australia; (R.X.); (C.L.); (O.D.A.); (D.A.P.)
| | - Oreoluwa Daniel Adeyinka
- Ken Parker Brain Tumour Research Laboratories, Brain and Mind Centre, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2006, Australia; (R.X.); (C.L.); (O.D.A.); (D.A.P.)
| | - Dula Asheka Pieris
- Ken Parker Brain Tumour Research Laboratories, Brain and Mind Centre, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2006, Australia; (R.X.); (C.L.); (O.D.A.); (D.A.P.)
| | - Svetlana Cherepanoff
- St Vincent’s Hospital, Victoria Street, Darlinghurst, NSW 2010, Australia; (S.C.); (G.G.)
- Department of Neuropathology, RPA Hospital and Brain and Mind Centre, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2006, Australia; (M.L.); (M.E.B.)
| | - Gary Gracie
- St Vincent’s Hospital, Victoria Street, Darlinghurst, NSW 2010, Australia; (S.C.); (G.G.)
| | - Maggie Lee
- Department of Neuropathology, RPA Hospital and Brain and Mind Centre, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2006, Australia; (M.L.); (M.E.B.)
| | - Kerrie L. McDonald
- Cooperative Trials Group of Neuro-Oncology (COGNO), Sydney, NSW 1450, Australia; (K.L.M.); (A.K.N.); (R.B.)
- Brain Cancer Consultancy, Sydney, NSW 2040, Australia
| | - Anna K. Nowak
- Cooperative Trials Group of Neuro-Oncology (COGNO), Sydney, NSW 1450, Australia; (K.L.M.); (A.K.N.); (R.B.)
- Department of Medical Oncology, University of Western Australia, Perth, WA 6009, Australia
| | - Richard Banati
- Cooperative Trials Group of Neuro-Oncology (COGNO), Sydney, NSW 1450, Australia; (K.L.M.); (A.K.N.); (R.B.)
- Life Sciences, Australian Nuclear Science and Technology Organisation, Sydney, NSW 2234, Australia
- Medical Imaging and Radiation Sciences, Brain and Mind Centre, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2006, Australia
| | - Michael E. Buckland
- Department of Neuropathology, RPA Hospital and Brain and Mind Centre, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2006, Australia; (M.L.); (M.E.B.)
- Cooperative Trials Group of Neuro-Oncology (COGNO), Sydney, NSW 1450, Australia; (K.L.M.); (A.K.N.); (R.B.)
| | - Manuel B. Graeber
- Ken Parker Brain Tumour Research Laboratories, Brain and Mind Centre, Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2006, Australia; (R.X.); (C.L.); (O.D.A.); (D.A.P.)
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Betlazar C, Middleton RJ, Banati R, Liu GJ. The Translocator Protein (TSPO) in Mitochondrial Bioenergetics and Immune Processes. Cells 2020; 9:cells9020512. [PMID: 32102369 PMCID: PMC7072813 DOI: 10.3390/cells9020512] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Revised: 02/19/2020] [Accepted: 02/19/2020] [Indexed: 12/11/2022] Open
Abstract
The translocator protein (TSPO) is an outer mitochondrial membrane protein that is widely used as a biomarker of neuroinflammation, being markedly upregulated in activated microglia in a range of brain pathologies. Despite its extensive use as a target in molecular imaging studies, the exact cellular functions of this protein remain in question. The long-held view that TSPO plays a fundamental role in the translocation of cholesterol through the mitochondrial membranes, and thus, steroidogenesis, has been disputed by several groups with the advent of TSPO knockout mouse models. Instead, much evidence is emerging that TSPO plays a fundamental role in cellular bioenergetics and associated mitochondrial functions, also part of a greater role in the innate immune processes of microglia. In this review, we examine the more direct experimental literature surrounding the immunomodulatory effects of TSPO. We also review studies which highlight a more central role for TSPO in mitochondrial processes, from energy metabolism, to the propagation of inflammatory responses through reactive oxygen species (ROS) modulation. In this way, we highlight a paradigm shift in approaches to TSPO functioning.
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Affiliation(s)
- Calina Betlazar
- Human Health, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia; (R.J.M.); (R.B.)
- Discipline of Medical Imaging & Radiation Sciences, Faculty of Medicine and Health, Brain and Mind Centre, University of Sydney, 94 Mallett Street, Camperdown, NSW 2050, Australia
- Correspondence: (C.B.); (G-J.L.)
| | - Ryan J. Middleton
- Human Health, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia; (R.J.M.); (R.B.)
| | - Richard Banati
- Human Health, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia; (R.J.M.); (R.B.)
- Discipline of Medical Imaging & Radiation Sciences, Faculty of Medicine and Health, Brain and Mind Centre, University of Sydney, 94 Mallett Street, Camperdown, NSW 2050, Australia
| | - Guo-Jun Liu
- Human Health, Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia; (R.J.M.); (R.B.)
- Discipline of Medical Imaging & Radiation Sciences, Faculty of Medicine and Health, Brain and Mind Centre, University of Sydney, 94 Mallett Street, Camperdown, NSW 2050, Australia
- Correspondence: (C.B.); (G-J.L.)
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Betlazar C, Harrison-Brown M, Middleton RJ, Banati R, Liu GJ. Cellular Sources and Regional Variations in the Expression of the Neuroinflammatory Marker Translocator Protein (TSPO) in the Normal Brain. Int J Mol Sci 2018; 19:ijms19092707. [PMID: 30208620 PMCID: PMC6163555 DOI: 10.3390/ijms19092707] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2018] [Revised: 09/09/2018] [Accepted: 09/09/2018] [Indexed: 02/07/2023] Open
Abstract
The inducible expression of the mitochondrial translocator protein 18 kDa (TSPO) by activated microglia is a prominent, regular feature of acute and chronic-progressive brain pathology. This expression is also the rationale for the continual development of new TSPO binding molecules for the diagnosis of "neuroinflammation" by molecular imaging. However, there is in the normal brain an ill-defined, low-level constitutive expression of TSPO. Taking advantage of healthy TSPO knockout mouse brain tissue to validate TSPO antibody specificity, this study uses immunohistochemistry to determine the regional distribution and cellular sources of TSPO in the normal mouse brain. Fluorescence microscopy revealed punctate TSPO immunostaining in vascular endothelial cells throughout the brain. In the olfactory nerve layers and glomeruli of the olfactory bulb, choroid plexus and ependymal layers, we confirm constitutive TSPO expression levels similar to peripheral organs, while some low TSPO expression is present in regions of known neurogenesis, as well as cerebellar Purkinje cells. The distributed-sparse expression of TSPO in endothelial mitochondria throughout the normal brain can be expected to give rise to a low baseline signal in TSPO molecular imaging studies. Finally, our study emphasises the need for valid and methodologically robust verification of the selectivity of TSPO ligands through the use of TSPO knockout tissues.
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Affiliation(s)
- Calina Betlazar
- Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia.
- Discipline of Medical Imaging & Radiation Sciences, Faculty of Medicine and Health, Brain and Mind Centre, University of Sydney, 94 Mallett Street, Camperdown, NSW 2050, Australia.
| | - Meredith Harrison-Brown
- Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia.
- Discipline of Medical Imaging & Radiation Sciences, Faculty of Medicine and Health, Brain and Mind Centre, University of Sydney, 94 Mallett Street, Camperdown, NSW 2050, Australia.
| | - Ryan J Middleton
- Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia.
| | - Richard Banati
- Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia.
- Discipline of Medical Imaging & Radiation Sciences, Faculty of Medicine and Health, Brain and Mind Centre, University of Sydney, 94 Mallett Street, Camperdown, NSW 2050, Australia.
| | - Guo-Jun Liu
- Australian Nuclear Science and Technology Organisation, New Illawarra Road, Lucas Heights, NSW 2234, Australia.
- Discipline of Medical Imaging & Radiation Sciences, Faculty of Medicine and Health, Brain and Mind Centre, University of Sydney, 94 Mallett Street, Camperdown, NSW 2050, Australia.
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Cumming P, Burgher B, Patkar O, Breakspear M, Vasdev N, Thomas P, Liu GJ, Banati R. Sifting through the surfeit of neuroinflammation tracers. J Cereb Blood Flow Metab 2018; 38:204-224. [PMID: 29256293 PMCID: PMC5951023 DOI: 10.1177/0271678x17748786] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 10/26/2017] [Accepted: 11/09/2017] [Indexed: 01/09/2023]
Abstract
The first phase of molecular brain imaging of microglial activation in neuroinflammatory conditions began some 20 years ago with the introduction of [11C]-( R)-PK11195, the prototype isoquinoline ligand for translocator protein (18 kDa) (TSPO). Investigations by positron emission tomography (PET) revealed microgliosis in numerous brain diseases, despite the rather low specific binding signal imparted by [11C]-( R)-PK11195. There has since been enormous expansion of the repertoire of TSPO tracers, many with higher specific binding, albeit complicated by allelic dependence of the affinity. However, the specificity of TSPO PET for revealing microglial activation not been fully established, and it has been difficult to judge the relative merits of the competing tracers and analysis methods with respect to their sensitivity for detecting microglial activation. We therefore present a systematic comparison of 13 TSPO PET and single photon computed tomography (SPECT) tracers belonging to five structural classes, each of which has been investigated by compartmental analysis in healthy human brain relative to a metabolite-corrected arterial input. We emphasize the need to establish the non-displaceable binding component for each ligand and conclude with five recommendations for a standard approach to define the cellular distribution of TSPO signals, and to characterize the properties of candidate TSPO tracers.
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Affiliation(s)
- Paul Cumming
- School of Psychology and Counselling and IHBI, Faculty of Health, Queensland University of Technology, Brisbane, Australia
- QIMR Berghofer Institute, Brisbane, Australia
| | - Bjorn Burgher
- QIMR Berghofer Institute, Brisbane, Australia
- Metro North Mental Health Service, Brisbane, Australia
| | - Omkar Patkar
- School of Psychology and Counselling and IHBI, Faculty of Health, Queensland University of Technology, Brisbane, Australia
- QIMR Berghofer Institute, Brisbane, Australia
| | - Michael Breakspear
- QIMR Berghofer Institute, Brisbane, Australia
- Metro North Mental Health Service, Brisbane, Australia
| | - Neil Vasdev
- Division of Nuclear Medicine and Molecular Imaging, Massachusetts General Hospital, Boston, MA, USA
- Department of Radiology, Harvard Medical School, Boston, MA, USA
| | - Paul Thomas
- Herston Imaging Research Facility, Faculty of Medicine, University of Queensland Centre for Clinical Research, Herston, Australia
| | - Guo-Jun Liu
- Australian Nuclear Science and Technology Organisation, Lucas Heights, Australia
- National Imaging Facility, Brain and Mind Centre and Faculty of Health Sciences, University of Sydney, Camperdown, Australia
| | - Richard Banati
- Australian Nuclear Science and Technology Organisation, Lucas Heights, Australia
- National Imaging Facility, Brain and Mind Centre and Faculty of Health Sciences, University of Sydney, Camperdown, Australia
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Di Biase MA, Zalesky A, O'keefe G, Laskaris L, Baune BT, Weickert CS, Olver J, McGorry PD, Amminger GP, Nelson B, Scott AM, Hickie I, Banati R, Turkheimer F, Yaqub M, Everall IP, Pantelis C, Cropley V. PET imaging of putative microglial activation in individuals at ultra-high risk for psychosis, recently diagnosed and chronically ill with schizophrenia. Transl Psychiatry 2017; 7:e1225. [PMID: 28850113 PMCID: PMC5611755 DOI: 10.1038/tp.2017.193] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2017] [Accepted: 06/23/2017] [Indexed: 01/22/2023] Open
Abstract
We examined putative microglial activation as a function of illness course in schizophrenia. Microglial activity was quantified using [11C](R)-(1-[2-chrorophynyl]-N-methyl-N-[1-methylpropyl]-3 isoquinoline carboxamide (11C-(R)-PK11195) positron emission tomography (PET) in: (i) 10 individuals at ultra-high risk (UHR) of psychosis; (ii) 18 patients recently diagnosed with schizophrenia; (iii) 15 patients chronically ill with schizophrenia; and, (iv) 27 age-matched healthy controls. Regional-binding potential (BPND) was calculated using the simplified reference-tissue model with four alternative reference inputs. The UHR, recent-onset and chronic patient groups were compared to age-matched healthy control groups to examine between-group BPND differences in 6 regions: dorsal frontal, orbital frontal, anterior cingulate, medial temporal, thalamus and insula. Correlation analysis tested for BPND associations with gray matter volume, peripheral cytokines and clinical variables. The null hypothesis of equality in BPND between patients (UHR, recent-onset and chronic) and respective healthy control groups (younger and older) was not rejected for any group comparison or region. Across all subjects, BPND was positively correlated to age in the thalamus (r=0.43, P=0.008, false discovery rate). No correlations with regional gray matter, peripheral cytokine levels or clinical symptoms were detected. We therefore found no evidence of microglial activation in groups of individuals at high risk, recently diagnosed or chronically ill with schizophrenia. While the possibility of 11C-(R)-PK11195-binding differences in certain patient subgroups remains, the patient cohorts in our study, who also displayed normal peripheral cytokine profiles, do not substantiate the assumption of microglial activation in schizophrenia as a regular and defining feature, as measured by 11C-(R)-PK11195 BPND.
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Affiliation(s)
- M A Di Biase
- Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne and Melbourne Health, Carlton South, VIC, Australia
- Department of Psychiatry, The University of Melbourne, Parkville, VIC Australia
| | - A Zalesky
- Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne and Melbourne Health, Carlton South, VIC, Australia
- Department of Psychiatry, The University of Melbourne, Parkville, VIC Australia
- Melbourne School of Engineering, The University of Melbourne, Parkville, VIC Australia
| | - G O'keefe
- Department of Molecular Imaging and Therapy, The University of Melbourne, Heidelberg, VIC Australia
- Department of Medicine, The University of Melbourne, and La Trobe University, Austin Hospital, Heidelberg, VIC, Australia
| | - L Laskaris
- Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne and Melbourne Health, Carlton South, VIC, Australia
- Department of Psychiatry, The University of Melbourne, Parkville, VIC Australia
| | - B T Baune
- Discipline of Psychiatry, The University of Adelaide, Adelaide, SA, Australia
| | - C S Weickert
- Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne and Melbourne Health, Carlton South, VIC, Australia
- Neuroscience Research Australia, Randwick, NSW, Australia
- Schizophrenia Research Institute, Randwick, NSW, Australia
- School of Psychiatry, University of New South Wales, Sydney, NSW, Australia
| | - J Olver
- Department of Psychiatry, The University of Melbourne, Parkville, VIC Australia
- Department of Molecular Imaging and Therapy, The University of Melbourne, Heidelberg, VIC Australia
- Department of Medicine, The University of Melbourne, and La Trobe University, Austin Hospital, Heidelberg, VIC, Australia
| | - P D McGorry
- Orygen, The National Centre of Excellence in Youth Mental Health, Parkville, VIC, Australia
- Centre for Youth Mental Health, The University of Melbourne, Parkville, VIC, Australia
| | - G P Amminger
- Orygen, The National Centre of Excellence in Youth Mental Health, Parkville, VIC, Australia
| | - B Nelson
- Orygen, The National Centre of Excellence in Youth Mental Health, Parkville, VIC, Australia
| | - A M Scott
- Department of Molecular Imaging and Therapy, The University of Melbourne, Heidelberg, VIC Australia
- Department of Medicine, The University of Melbourne, and La Trobe University, Austin Hospital, Heidelberg, VIC, Australia
| | - I Hickie
- Brain & Mind Centre, The University of Sydney, Camperdown, NSW, Australia
| | - R Banati
- Medical Radiation Sciences, The University of Sydney, Camperdown, NSW, Australia
| | - F Turkheimer
- Department of Neuroimaging, King’s College London, London, UK
| | - M Yaqub
- VU University Medical Center, Amsterdam, The Netherlands
| | - I P Everall
- Department of Psychiatry, The University of Melbourne, Parkville, VIC Australia
- North Western Mental Health, Melbourne Health, Parkville, VIC, Australia
- Florey Institute for Neurosciences and Mental Health, Parkville, VIC, Australia
- Centre for Neural Engineering, Department of Electrical and Electronic Engineering, The University of Melbourne, Carlton South, VIC, Australia
- Cooperative Research Centre for Mental Health, Carlton, VIC, Australia
| | - C Pantelis
- Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne and Melbourne Health, Carlton South, VIC, Australia
- Department of Psychiatry, The University of Melbourne, Parkville, VIC Australia
- North Western Mental Health, Melbourne Health, Parkville, VIC, Australia
- Florey Institute for Neurosciences and Mental Health, Parkville, VIC, Australia
- Centre for Neural Engineering, Department of Electrical and Electronic Engineering, The University of Melbourne, Carlton South, VIC, Australia
- Cooperative Research Centre for Mental Health, Carlton, VIC, Australia
| | - V Cropley
- Melbourne Neuropsychiatry Centre, Department of Psychiatry, The University of Melbourne and Melbourne Health, Carlton South, VIC, Australia
- Department of Psychiatry, The University of Melbourne, Parkville, VIC Australia
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Harrison-Brown M, Liu GJ, Banati R. Checkpoints to the Brain: Directing Myeloid Cell Migration to the Central Nervous System. Int J Mol Sci 2016; 17:E2030. [PMID: 27918464 PMCID: PMC5187830 DOI: 10.3390/ijms17122030] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 11/23/2016] [Accepted: 11/25/2016] [Indexed: 12/13/2022] Open
Abstract
Myeloid cells are a unique subset of leukocytes with a diverse array of functions within the central nervous system during health and disease. Advances in understanding of the unique properties of these cells have inspired interest in their use as delivery vehicles for therapeutic genes, proteins, and drugs, or as "assistants" in the clean-up of aggregated proteins and other molecules when existing drainage systems are no longer adequate. The trafficking of myeloid cells from the periphery to the central nervous system is subject to complex cellular and molecular controls with several 'checkpoints' from the blood to their destination in the brain parenchyma. As important components of the neurovascular unit, the functional state changes associated with lineage heterogeneity of myeloid cells are increasingly recognized as important for disease progression. In this review, we discuss some of the cellular elements associated with formation and function of the neurovascular unit, and present an update on the impact of myeloid cells on central nervous system (CNS) diseases in the laboratory and the clinic. We then discuss emerging strategies for harnessing the potential of site-directed myeloid cell homing to the CNS, and identify promising avenues for future research, with particular emphasis on the importance of untangling the functional heterogeneity within existing myeloid subsets.
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Affiliation(s)
- Meredith Harrison-Brown
- Discipline of Medical Imaging & Radiation Sciences, Faculty of Health Sciences, The University of Sydney, Sydney, NSW 2141, Australia.
- Australian Nuclear Science and Technology Organisation, Sydney, NSW 2234, Australia.
| | - Guo-Jun Liu
- Discipline of Medical Imaging & Radiation Sciences, Faculty of Health Sciences, The University of Sydney, Sydney, NSW 2141, Australia.
- Australian Nuclear Science and Technology Organisation, Sydney, NSW 2234, Australia.
| | - Richard Banati
- Discipline of Medical Imaging & Radiation Sciences, Faculty of Health Sciences, The University of Sydney, Sydney, NSW 2141, Australia.
- Australian Nuclear Science and Technology Organisation, Sydney, NSW 2234, Australia.
- Brain and Mind Centre, The University of Sydney, Sydney, NSW 2006, Australia.
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11
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McNamara AL, Kam WWY, Scales N, McMahon SJ, Bennett JW, Byrne HL, Schuemann J, Paganetti H, Banati R, Kuncic Z. Dose enhancement effects to the nucleus and mitochondria from gold nanoparticles in the cytosol. Phys Med Biol 2016; 61:5993-6010. [PMID: 27435339 DOI: 10.1088/0031-9155/61/16/5993] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Gold nanoparticles (GNPs) have shown potential as dose enhancers for radiation therapy. Since damage to the genome affects the viability of a cell, it is generally assumed that GNPs have to localise within the cell nucleus. In practice, however, GNPs tend to localise in the cytoplasm yet still appear to have a dose enhancing effect on the cell. Whether this effect can be attributed to stress-induced biological mechanisms or to physical damage to extra-nuclear cellular targets is still unclear. There is however growing evidence to suggest that the cellular response to radiation can also be influenced by indirect processes induced when the nucleus is not directly targeted by radiation. The mitochondrion in particular may be an effective extra-nuclear radiation target given its many important functional roles in the cell. To more accurately predict the physical effect of radiation within different cell organelles, we measured the full chemical composition of a whole human lymphocytic JURKAT cell as well as two separate organelles; the cell nucleus and the mitochondrion. The experimental measurements found that all three biological materials had similar ionisation energies ∼70 eV, substantially lower than that of liquid water ∼78 eV. Monte Carlo simulations for 10-50 keV incident photons showed higher energy deposition and ionisation numbers in the cell and organelle materials compared to liquid water. Adding a 1% mass fraction of gold to each material increased the energy deposition by a factor of ∼1.8 when averaged over all incident photon energies. Simulations of a realistic compartmentalised cell show that the presence of gold in the cytosol increases the energy deposition in the mitochondrial volume more than within the nuclear volume. We find this is due to sub-micron delocalisation of energy by photoelectrons, making the mitochondria a potentially viable indirect radiation target for GNPs that localise to the cytosol.
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Affiliation(s)
- A L McNamara
- Department of Radiation Oncology, Massachusetts General Hospital, Harvard Medical School, 30 Fruit St, Boston, MA 02114, USA. School of Physics, University of Sydney, NSW 2006, Australia
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12
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Kam W, Banati R. 100: Delayed and Persistent Response of Human Mitochondria after Single Exposure to 0.5 to 4 Gy of Gamma Radiation. Radiother Oncol 2014. [DOI: 10.1016/s0167-8140(15)34121-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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13
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Kam WWY, Lake V, Banos C, Davies J, Banati R. Apparent polyploidization after gamma irradiation: pitfalls in the use of quantitative polymerase chain reaction (qPCR) for the estimation of mitochondrial and nuclear DNA gene copy numbers. Int J Mol Sci 2013; 14:11544-59. [PMID: 23722662 PMCID: PMC3709747 DOI: 10.3390/ijms140611544] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Revised: 04/18/2013] [Accepted: 05/16/2013] [Indexed: 12/12/2022] Open
Abstract
Quantitative polymerase chain reaction (qPCR) has been widely used to quantify changes in gene copy numbers after radiation exposure. Here, we show that gamma irradiation ranging from 10 to 100 Gy of cells and cell-free DNA samples significantly affects the measured qPCR yield, due to radiation-induced fragmentation of the DNA template and, therefore, introduces errors into the estimation of gene copy numbers. The radiation-induced DNA fragmentation and, thus, measured qPCR yield varies with temperature not only in living cells, but also in isolated DNA irradiated under cell-free conditions. In summary, the variability in measured qPCR yield from irradiated samples introduces a significant error into the estimation of both mitochondrial and nuclear gene copy numbers and may give spurious evidence for polyploidization.
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Affiliation(s)
- Winnie W. Y. Kam
- Australian Nuclear Science and Technology Organisation, Lucas Heights, Sydney, New South Wales 2234, Australia; E-Mails: (V.L.); (C.B.); (J.D.); (R.B.)
- Medical Radiation Sciences, Faculty of Health Sciences, University of Sydney, Cumberland, Sydney, New South Wales 2141, Australia
- Author to whom correspondence should be addressed; E-Mail: or ; Tel.: +61-2-9717-7241; Fax: +61-2-9717-9262
| | - Vanessa Lake
- Australian Nuclear Science and Technology Organisation, Lucas Heights, Sydney, New South Wales 2234, Australia; E-Mails: (V.L.); (C.B.); (J.D.); (R.B.)
| | - Connie Banos
- Australian Nuclear Science and Technology Organisation, Lucas Heights, Sydney, New South Wales 2234, Australia; E-Mails: (V.L.); (C.B.); (J.D.); (R.B.)
| | - Justin Davies
- Australian Nuclear Science and Technology Organisation, Lucas Heights, Sydney, New South Wales 2234, Australia; E-Mails: (V.L.); (C.B.); (J.D.); (R.B.)
- School of Physics, University of Sydney, Camperdown, Sydney, New South Wales 2006, Australia
| | - Richard Banati
- Australian Nuclear Science and Technology Organisation, Lucas Heights, Sydney, New South Wales 2234, Australia; E-Mails: (V.L.); (C.B.); (J.D.); (R.B.)
- Medical Radiation Sciences, Faculty of Health Sciences, University of Sydney, Cumberland, Sydney, New South Wales 2141, Australia
- National Imaging Facility at Brain and Mind Research Institute (BMRI), University of Sydney, Camperdown, Sydney, New South Wales 2050, Australia
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Naidoo-Variawa S, Lehnert W, Kassiou M, Banati R, Meikle SR. Attenuation correction for the large non-human primate brain imaging using microPET. Phys Med Biol 2010; 55:2351-63. [DOI: 10.1088/0031-9155/55/8/015] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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15
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Hickie IB, Banati R, Stewart CH, Lloyd AR. Are common childhood or adolescent infections risk factors for schizophrenia and other psychotic disorders? Med J Aust 2009; 190:S17-21. [DOI: 10.5694/j.1326-5377.2009.tb02652.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Accepted: 12/17/2008] [Indexed: 11/17/2022]
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16
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Banati R, Hickie IB. Therapeutic signposts: using biomarkers to guide better treatment of schizophrenia and other psychotic disorders. Med J Aust 2009; 190:S26-32. [DOI: 10.5694/j.1326-5377.2009.tb02371.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Accepted: 11/12/2008] [Indexed: 11/17/2022]
Affiliation(s)
- Richard Banati
- Brain and Mind Research Institute, University of Sydney, Sydney, NSW
- ANSTO, Sydney, NSW
| | - Ian B Hickie
- Brain and Mind Research Institute, University of Sydney, Sydney, NSW
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Affiliation(s)
- Ian B Hickie
- Brain and Mind Research Institute, University of Sydney, Sydney, NSW
| | | | - Claire H Stewart
- Brain and Mind Research Institute, University of Sydney, Sydney, NSW
| | - Andrew R Lloyd
- Inflammation Research Unit, School of Pathology, University of New South Wales, Sydney, NSW
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18
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Naidoo-Variawa S, Hey-Cunningham AJ, Lehnert W, Kench PL, Kassiou M, Banati R, Meikle SR. High-resolution imaging of the large non-human primate brain using microPET: a feasibility study. Phys Med Biol 2007; 52:6627-38. [PMID: 17975287 DOI: 10.1088/0031-9155/52/22/005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The neuroanatomy and physiology of the baboon brain closely resembles that of the human brain and is well suited for evaluating promising new radioligands in non-human primates by PET and SPECT prior to their use in humans. These studies are commonly performed on clinical scanners with 5 mm spatial resolution at best, resulting in sub-optimal images for quantitative analysis. This study assessed the feasibility of using a microPET animal scanner to image the brains of large non-human primates, i.e. papio hamadryas (baboon) at high resolution. Factors affecting image accuracy, including scatter, attenuation and spatial resolution, were measured under conditions approximating a baboon brain and using different reconstruction strategies. Scatter fraction measured 32% at the centre of a 10 cm diameter phantom. Scatter correction increased image contrast by up to 21% but reduced the signal-to-noise ratio. Volume resolution was superior and more uniform using maximum a posteriori (MAP) reconstructed images (3.2-3.6 mm(3) FWHM from centre to 4 cm offset) compared to both 3D ordered subsets expectation maximization (OSEM) (5.6-8.3 mm(3)) and 3D reprojection (3DRP) (5.9-9.1 mm(3)). A pilot (18)F-2-fluoro-2-deoxy-d-glucose ([(18)F]FDG) scan was performed on a healthy female adult baboon. The pilot study demonstrated the ability to adequately resolve cortical and sub-cortical grey matter structures in the baboon brain and improved contrast when images were corrected for attenuation and scatter and reconstructed by MAP. We conclude that high resolution imaging of the baboon brain with microPET is feasible with appropriate choices of reconstruction strategy and corrections for degrading physical effects. Further work to develop suitable correction algorithms for high-resolution large primate imaging is warranted.
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Affiliation(s)
- S Naidoo-Variawa
- Discipline of Medical Radiation Sciences, Faculty of Health Sciences, University of Sydney, PO Box 170, Lidcombe, NSW 1825, Sydney, Australia
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Liu X, Banister SD, Christie MJ, Banati R, Meikle S, Coster MJ, Kassiou M. Trishomocubanes: Novel σ ligands modulate cocaine-induced behavioural effects. Eur J Pharmacol 2007; 555:37-42. [PMID: 17113074 DOI: 10.1016/j.ejphar.2006.10.020] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2006] [Revised: 10/04/2006] [Accepted: 10/06/2006] [Indexed: 10/24/2022]
Abstract
Trishomocubane analogues TC1 (N-(3'-fluorophenyl)ethyl-4-azahexacyclo [5.4.1.0(2,6).0(3,10).0(5,9).0(8,11)]dodecan-3-ol) and TC4 (N-(3'-fluorophenyl)methyl-4-azahexacyclo [5.4.1.0(2,6).0(3,10).0(5,9).0(8,11)]dodecan-3-ol) were evaluated for their modulatory effects on locomotor activity as well as interactions with cocaine-induced responses. TC1 and TC4 have high affinity and moderate to high selectivity for sigma(1) (Ki=10 nM, sigma1/sigma2=0.03) and sigma2 (Ki=20 nM, sigma1/sigma2=7.6) receptor subtypes respectively. Both compounds have negligible affinity for the dopamine (DAT), serotonin (SERT), and norepinephrine (NET) transporters. In behavioural studies, TC1 produced a dose-related inhibition in spontaneous locomotor activity measured in a Digiscan apparatus. TC1 attenuated the stimulatory locomotor effect of 20 mg/kg cocaine with a half-maximal depressant activity (ID50) of 38.6 mg/kg. TC1 (dose range of 25 to 100 mg/kg) also partially substituted for the effect of cocaine (10 mg/kg) in a discriminative stimulus task, involving the trained discrimination between cocaine and saline using a two-lever choice method. Following a dose of 50 mg/kg TC1, a maximum of 31% substitution was reached. The response rate was reduced to 56% of vehicle control following a TC1 dose of 100 mg/kg. These behavioural effects suggest that TC1 can act as an antagonist via the sigma1 receptor. In contrast to TC1, TC4 produced a stimulant effect in locomotor activity with the ED50 estimated at 0.94 mg/kg. In addition, TC4 failed to inhibit cocaine-induced stimulation; neither did it substitute for the discriminative stimulus effects of cocaine. TC4 thus appears to interact predominantly with the sigma2 receptor subtype (sigma1/sigma2=7.6) which may result in dopamine stimulation independent of the effects of cocaine. The differential effect of TC1 and TC4 warrants further study of the mechanism of these actions. Present data also suggests a potential role for trishomocubane analogues in developing medication or research tools for cocaine addiction.
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Affiliation(s)
- Xiang Liu
- Department of Pharmacology, University of Sydney, NSW 2006, Australia
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21
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Raivich G, Banati R. Brain microglia and blood-derived macrophages: molecular profiles and functional roles in multiple sclerosis and animal models of autoimmune demyelinating disease. ACTA ACUST UNITED AC 2005; 46:261-81. [PMID: 15571769 DOI: 10.1016/j.brainresrev.2004.06.006] [Citation(s) in RCA: 170] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/01/2004] [Indexed: 12/23/2022]
Abstract
Microglia and macrophages, one a brain-resident, the other a mostly hematogenous cell type, represent two related cell types involved in the brain pathology in multiple sclerosis and its autoimmune animal model, the experimental allergic encephalomyelitis. Together, they perform a variety of different functions: they are the primary sensors of brain pathology, they are rapidly recruited to sites of infection, trauma or autoimmune inflammation in experimental allergic encephalomyelitis and multiple sclerosis and they are competent presenters of antigen and interact with T cells recruited to the inflamed CNS. They also synthesise a variety of molecules, such as cytokines (TNF, interleukins), chemokines, accessory molecules (B7, CD40), complement, cell adhesion glycoproteins (integrins, selectins), reactive oxygen radicals and neurotrophins, that could exert a damaging or a protective effect on adjacent axons, myelin and oligodendrocytes. The current review will give a detailed summary on their cellular response, describe the different classes of molecules expressed and their attribution to the blood derived or brain-resident macrophages and then discuss how these molecules contribute to the neuropathology. Recent advances using chimaeric and genetically modified mice have been particularly telling about the specific, overlapping and nonoverlapping roles of macrophages and microglia in the demyelinating disease. Interestingly, they point to a crucial role of hematogenous macrophages in initiating inflammation and myelin removal, and that of microglia in checking excessive response and in the induction and maintenance of remission.
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Affiliation(s)
- Gennadij Raivich
- Department of Anatomy, Obstetrics and Gynaecology, Perinatal Brain Repair Centre, University College London, Chenies Mews 86-96 WC1E 6HX London, UK.
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Duke DC, Moran LB, Turkheimer FE, Banati R, Graeber MB. Microglia in Culture: What Genes Do They Express? Dev Neurosci 2004; 26:30-7. [PMID: 15509896 DOI: 10.1159/000080709] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2004] [Accepted: 05/06/2004] [Indexed: 11/19/2022] Open
Abstract
The cell culture model utilized in this study represents one of the most widely used paradigms of microglia in vitro. After 14 days, microglia harvested from the neonatal rat brain are considered 'mature'. However, it is clear that this represents a somewhat arbitrary definition. In this paper, we provide a transcriptome definition of such microglial cells. More than 7,000 known genes and 1,000 expressed sequence tag clusters were analysed. 'Microglia genes' were defined as sequences consistently expressed in all microglia samples tested. Accordingly, 388 genes were identified as microglia genes. Another 1,440 sequences were detected in a subset of the cultures. Genes consistently expressed by microglia included genes known to be involved in the cellular immune response, brain tissue surveillance, microglial migration as well as proliferation. The expression profile reported here provides a baseline against which changes of microglia in vitro can be examined. Importantly, expression profiling of normal microglia will help to provide the presently purely operational definition of 'microglial activation' with a molecular biological correlate. Furthermore, the data reported here add to our understanding of microglia biology and allow projections as to what functions microglia may exert in vivo, as well as in vitro.
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Affiliation(s)
- D C Duke
- Department of Neuropathology, Division of Neuroscience and Psychological Medicine, Faculty of Medicine, Imperial College London, London, UK
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Schwarz SC, Kupsch AR, Banati R, Oertel WH. Cellular immune reactions in brain transplantation: effects of graft pooling and immunosuppression in the 6-hydroxydopamine rat model of Parkinson's disease. Glia 1996; 17:103-20. [PMID: 8776578 DOI: 10.1002/(sici)1098-1136(199606)17:2<103::aid-glia3>3.0.co;2-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
We used high immunogenic mouse and low immunogenic rat brain transplants to investigate the effect of pooling of tissue with immunogenetic disparity on cellular immune reactions. Foetal xenogenic mouse striatum and allogenic rat substantia nigra were implanted into i) the 6-hydroxydopamine lesioned striatum of outbred female Sprague-Dawley rats as a pooled cell suspension, or into ii) the unlesioned and lesioned striata as non-pooled separate deposits, with or without immunosuppressive treatment with cyclosporin A (Cy A). In control animals, iii) mouse striatum was replaced by rat striatum, and iv) sham grafts with and without immunosuppression. Six weeks post grafting, brains were semiquantitatively processed using immunocytochemical markers for microglia, astrocytes, T-helper cells, and macrophages, major histocompatibility class (MHC) I and II expression. The total amount of immunoreactivity (PA) for microglial cells and astrocytes was pronounced and the PA for T-helper cells and macrophages was doubled in recipients of pooled rat and mouse cografts compared to non-pooled deposits, indicating ongoing immune reactions with participation of glial cells. MHC I expression was significantly increased in pooled xeno- and allogenic cografts with and without immunosuppression compared to allogenic controls. Expression of MHC II was significantly increased in pooled cografts without immunosuppression. In recipients of separate, non-pooled heteroimmunogenic cotransplants, MHC I and II expression was significantly increased in xenogenic deposits with and without immunosuppression. MHC II was as well significantly increased in allogenic deposits without immunosuppression. Immunosuppressed animals with non-pooled allogenic mouse cografts showed low levels of cellular immune parameters. In conclusion non-pooled heteroimmunogenic grafts lead to less pronounced immune reactions compared to pooled grafts and immunosuppressive treatment with Cy A has a beneficial effect on acute transplant-associated immune parameters.
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Affiliation(s)
- S C Schwarz
- Department of Neurology, Klinikum Grosshadern, Munich, Germany
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24
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Töpper R, Gehrmann J, Banati R, Schwarz M, Block F, Noth J, Kreutzberg GW. Rapid appearance of beta-amyloid precursor protein immunoreactivity in glial cells following excitotoxic brain injury. Acta Neuropathol 1995; 89:23-8. [PMID: 7709727 DOI: 10.1007/bf00294255] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Clinical and experimental data have indicated an up-regulation of amyloid precursor protein (APP) after various types of CNS injury. In the present study the cellular source of lesion-induced APP has been investigated in a neurotoxic CNS model. Quinolinic acid injection into the striatum results in neuronal degeneration, while glial cells survive. APP immunoreactivity was detected in glial cells starting at postoperative day 3 and persisted until day 21, the last time point studied. Double immunocytochemistry identified the majority of APP-immunoreactive cells as glial fibrillary acidic protein-immunoreactive astrocytes. There was no evidence of amyloid fibril deposition during this time. It is concluded that following excitotoxic neuronal degneration APP is mainly produced by reactive astrocytes in the lesioned area.
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Affiliation(s)
- R Töpper
- Max-Planck-Institute of Psychiatry, Department of Neuromorphology, Martinsried, Germany
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25
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Walz W, Ilschner S, Ohlemeyer C, Banati R, Kettenmann H. Extracellular ATP activates a cation conductance and a K+ conductance in cultured microglial cells from mouse brain. J Neurosci 1993; 13:4403-11. [PMID: 7692013 PMCID: PMC6576379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Microglial cells have important functions during regenerative processes after brain injury. It is well established that they rapidly respond to damage to the brain tissue. Stages of activation are associated with changes of cellular properties such as proliferation rate or expression of surface antigens. Yet, nothing is known about signal substances leading to the rapid changes of membrane properties, which may be required to initiate the transition from one cell stage into another. From our present study, using the patch-clamp technique, we report that cultured microglial cells obtained from mouse or rat brain respond to extracellularly applied ATP with the activation of a cation conductance. Additionally, in the majority of cells an outwardly directed K+ conductance was activated with some delay. Since ADP, AMP, and adenosine (in descending order) were less potent or ineffective in inducing the cation conductance, the involvement of a P2 purinergic receptor is proposed. The receptor activation is accompanied by an increase of cytosolic Ca2+ as determined by a fura-2-based Ca(2+)-imaging system. This ATP receptor could enable microglial cells to respond to transmitter release from nerve endings with ATP as a transmitter or cotransmitter or to the death of cells with resulting leakage of ATP.
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Affiliation(s)
- W Walz
- Department of Physiology, University of Saskatchewan, Saskatoon, Canada
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26
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Abstract
Several reports addressed the issue of how the alternative splicing of exon 7 and 8 in the APP pre-mRNA is regulated in different tissues. Of special interest here was the potential involvement of exon 7 containing APP splice isoforms, since this exon codes for a serine protease inhibitor and is therefore of putative relevance for amyloidogenic catabolism of the precursor protein. The recent identification of a third alternative splice site in close proximity to the beta A4-amyloid portion in the APP gene which may also increase APP amyloidogenicity, allowed us to investigate its regulation in cells of the central nervous system. With our assay, we were able to resolve six different APP isoforms of the eight potential isoforms which can be generated from the three alternatively spliced exons 7, 8, and 15. We demonstrate here that, in addition to rat brain microglia cells, astrocyte-enriched cultures also skip the novel alternative 3'-splice site in front of exon 15, generating L-APP mRNA. Neurons are the only cells in the central nervous system which seem to use the 3'-splice site of intron 14 nearly 100%. Interestingly, this very 3'-splice site is the only one present in the APP gene that completely matches the consensus sequence for the branchpoint sequence proposed for introns. We would therefore suggest that neurons lack a specific splicing factor which inhibits the use of the rather strong 3'-splice site in front of exon 15. It remains to be shown whether this is also the case for neurons in Alzheimer's disease.
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Affiliation(s)
- R Sandbrink
- Zentrum für Molekulare Biologie, Universität Heidelberg, Germany
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27
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Abstract
The present knowledge of voltage- and ligand-activated ion channels of cultured microglial cells is described and its relevance is discussed. All microglial cells cultured from rat or mouse brain express an inward rectifying K+ channel but no outward currents. This expression is not changed by the length of the cultivation period, nor is it different in freshly isolated cells. It makes the microglial cells distinct from peritoneal macrophages, which possess an outward rectifying K+ channel. In bone marrow, 2 populations of cells could be distinguished electrophysiologically, one with the channel pattern of macrophages and one with that of microglial cells. This finding is interesting in light of the fact that it is presently hypothesized that the differentiation of monocytes into microglia takes place exclusively during embryonic development but not in the adult. The available data thus support the hypothesis that within the bone marrow a population of macrophage precursor cells exists with a possible lineage relationship to brain macrophages. The lack of outward currents in the microglial cells has the functional consequence that even a small inward current leads to a large membrane depolarization, since K+ outward currents are not activated with the depolarization. The microglial cell is thus very sensitive to depolarizing events. We found that ATP induced an inward current and an increase in the conductance, whereas ADP, AMP, and adenosine did not. These relative potencies indicate that microglia possess a P2 purinoceptor linked to an ion channel. The amplitude of the inward current elicited by ATP is about 80 pA and is sufficient to depolarize microglial cells close to 0 mV.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- H Kettenmann
- Department of Neurobiology, University of Heidelberg, Germany
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28
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Gehrmann J, Mies G, Bonnekoh P, Banati R, Iijima T, Kreutzberg GW, Hossmann KA. Microglial reaction in the rat cerebral cortex induced by cortical spreading depression. Brain Pathol 1993; 3:11-7. [PMID: 8269080 DOI: 10.1111/j.1750-3639.1993.tb00720.x] [Citation(s) in RCA: 115] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The response of microglial cells to cortical spreading depression (CSD) was studied in rat brain by immunocytochemistry. CSD was elicited for one hour by the topical application of 4M potassium chloride solution and the microglial reaction examined immunocytochemically after 4, 16, 24 and 72 hours. CSD was sufficient to induce a microglial reaction throughout the cortex at 24 hours. Activated microglial cells furthermore showed a striking de-novo expression of major histocompatibility complex class II antigens. In contrast, no microglial reaction was observed in the cortex of sham-operated animals. This microglial reaction in response to CSD was not associated with histologically detectable neuronal damage. These results support the view that microglial cells are extremely sensitive to changes of the brain microenvironment. Their activation may be related to changes of ion homeostasis in the brain which are not sufficient to trigger neuronal injury.
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Affiliation(s)
- J Gehrmann
- Max-Planck-Institute of Psychiatry, Department of Neuromorphology, Martinsried/Munich, Germany
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29
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Affiliation(s)
- J Gehrmann
- Department of Neuromophology, Max-Planck-Institute of Psychiatry, Martinsried, Munich, Germany
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30
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Assfalg-Machleidt I, Rothe G, Klingel S, Banati R, Mangel WF, Valet G, Machleidt W. Membrane permeable fluorogenic rhodamine substrates for selective determination of cathepsin L. Biol Chem Hoppe Seyler 1992; 373:433-40. [PMID: 1515071 DOI: 10.1515/bchm3.1992.373.2.433] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The dipeptidyl rhodamine diamide substrates (Z-Phe-Arg)2-R110 and (Z-Arg-Arg)2-R110 are 820- and 360-fold more selective for cathepsin L than for cathepsin B allowing a sensitive determination of cathepsin L activity in the presence of high activity of cathepsin B. The results obtained with cell lysates suggest that the cysteine proteinase activity of vital macrophages detected by flow cytometry with these substrates is mainly due to cathepsin L.
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Affiliation(s)
- I Assfalg-Machleidt
- Institut für Physiologische Chemie, Physikalische Biochemie und Zellbiologie, Universität München
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31
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König G, Mönning U, Czech C, Prior R, Banati R, Schreiter-Gasser U, Bauer J, Masters CL, Beyreuther K. Identification and differential expression of a novel alternative splice isoform of the beta A4 amyloid precursor protein (APP) mRNA in leukocytes and brain microglial cells. J Biol Chem 1992; 267:10804-9. [PMID: 1587857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The gene for the beta A4-amyloid precursor protein (APP) consists of 19 exons which code for a typical N- and O-glycosylated transmembrane protein with four extracellular domains followed by the transmembrane domain and a short cytoplasmic domain. The beta A4-amyloid sequence is part of exons 16 and 17. Several APP isoforms can be generated by alternative splicing of exons 7 and 8, encoding domains with homologies to Kunitz-type protease inhibitors and the MRC OX-2 antigen, respectively. The mechanism by which the pathological beta A4 is generated is unknown, it is however a critical event in Alzheimer's disease and is distinct from the normally occurring cleavage and secretion of APPs within the beta A4 sequence. We report here for the first time considerable APP mRNA expression by rat brain microglial cells. In addition we showed by S1 nuclease protection and polymerase chain reaction analysis of reverse transcribed RNA (RT-PCR) that T-lymphocytes, macrophages, and microglial cells expressed a new APP isoform by selection of a novel alternative splice site and exclusion of exon 15 of the APP gene. This leads to a transmembrane, beta A4 sequence containing APP variant, lacking 18 amino acid residues close to the amyloidogenic region. The use of this novel alternative splice site alters the structure of APP in close proximity to the beta A4 region and thus may determine a variant, potentially pathogenic processing of leukocyte-derived APP in brain.
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Affiliation(s)
- G König
- Center for Molecular Biology (ZMBH), INF 282, University of Heidelberg, Germany
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32
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Kettenmann H, Hoppe D, Gottmann K, Banati R, Kreutzberg G. Cultured microglial cells have a distinct pattern of membrane channels different from peritoneal macrophages. J Neurosci Res 1990; 26:278-87. [PMID: 1697905 DOI: 10.1002/jnr.490260303] [Citation(s) in RCA: 182] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Microglia are the source of the resident macrophages of the brain and thus belong to one of the most reactive cell types in cerebral tissue. They are attributed to have an important role in a number of pathological conditions, such as multiple sclerosis, viral infections like AIDS, and in lethal or sublethal injuries of neurons where the blood-brain barrier is left intact (Streit et al., 1988; McGeer et al., 1988; Gendelman et al., 1989). Microglia share a number of macrophage characteristics but so far lack a distinguishing positive marker. In this study it is shown that microglia are distinguished from other macrophages by a unique pattern of ion channels. We compared membrane currents of microglial cells with those from peritoneal macrophages cultured under identical conditions. Although in macrophages a delayed outward K+ current was previously described (Randriamampita and Trautmann, 1987), microglial cells lacked any specific outward current. Instead, these cells were characterized by large inwardly rectifying currents, activated by hyperpolarizing voltage steps. The reversal potential in different K+ gradients and the sensitivity of the current to to Ba2+, TEA, and 4-AP indicates that this current is K+ selective. In single-channel recordings, a 30 pS K+ selective channel similar to the classical inward rectifier K+ channel was observed. Thus, the expression of membrane channels served not only to distinguish microglia from other cells inside and outside the brain, e.g., blood macrophages, but also suggests a unique functional state of this cell population.
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Affiliation(s)
- H Kettenmann
- Department of Neurobiology, University of Heidelberg, Federal Republic of Germany
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