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Nelvagal HR, Lange J, Takahashi K, Tarczyluk-Wells MA, Cooper JD. Pathomechanisms in the neuronal ceroid lipofuscinoses. Biochim Biophys Acta Mol Basis Dis 2020; 1866:165570. [DOI: 10.1016/j.bbadis.2019.165570] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 09/30/2019] [Accepted: 10/03/2019] [Indexed: 12/22/2022]
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Domowicz MS, Chan WC, Claudio-Vázquez P, Henry JG, Ware CB, Andrade J, Dawson G, Schwartz NB. Global Brain Transcriptome Analysis of a Tpp1 Neuronal Ceroid Lipofuscinoses Mouse Model. ASN Neuro 2020; 11:1759091419843393. [PMID: 31003587 PMCID: PMC6475859 DOI: 10.1177/1759091419843393] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
In humans, homozygous mutations in the TPP1 gene results in loss
of tripeptidyl peptidase 1 (TPP1) enzymatic activity, leading to late infantile
neuronal ceroid lipofuscinoses disease. Using a mouse model that targets the
Tpp1 gene and recapitulates the pathology and clinical
features of the human disease, we analyzed end-stage (4 months) transcriptional
changes associated with lack of TPP1 activity. Using RNA sequencing technology,
Tpp1 expression changes in the forebrain/midbrain and
cerebellum of 4-month-old homozygotes were compared with strain-related
controls. Transcriptional changes were found in 510 and 1,550 gene transcripts
in forebrain/midbrain and cerebellum, respectively, from
Tpp1-deficient brain tissues when compared with age-matched
controls. Analysis of the differentially expressed genes using the Ingenuity™
pathway software, revealed increased neuroinflammation activity in microglia and
astrocytes that could lead to neuronal dysfunction, particularly in the
cerebellum. We also observed upregulation in the production of nitric oxide and
reactive oxygen species; activation of leukocyte extravasation signals and
complement pathways; and downregulation of major transcription factors involved
in control of circadian rhythm. Several of these expression changes were
confirmed by independent quantitative polymerase chain reaction and histological
analysis by mRNA in situ hybridization, which allowed for an
in-depth anatomical analysis of the pathology and provided independent
confirmation of at least two of the major networks affected in this model. The
identification of differentially expressed genes has revealed new lines of
investigation for this complex disorder that may lead to novel therapeutic
targets.
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Affiliation(s)
- Miriam S Domowicz
- 1 Department of Pediatrics, Biological Sciences Division, The University of Chicago, IL, USA
| | - Wen-Ching Chan
- 2 Center for Research Informatics, Biological Sciences Division, The University of Chicago, IL, USA
| | | | - Judith G Henry
- 1 Department of Pediatrics, Biological Sciences Division, The University of Chicago, IL, USA
| | - Christopher B Ware
- 1 Department of Pediatrics, Biological Sciences Division, The University of Chicago, IL, USA
| | - Jorge Andrade
- 2 Center for Research Informatics, Biological Sciences Division, The University of Chicago, IL, USA
| | - Glyn Dawson
- 1 Department of Pediatrics, Biological Sciences Division, The University of Chicago, IL, USA
| | - Nancy B Schwartz
- 1 Department of Pediatrics, Biological Sciences Division, The University of Chicago, IL, USA.,3 Department of Biochemistry and Molecular Biology, Biological Sciences Division, The University of Chicago, IL, USA
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Preising MN, Abura M, Jäger M, Wassill KH, Lorenz B. Ocular morphology and function in juvenile neuronal ceroid lipofuscinosis (CLN3) in the first decade of life. Ophthalmic Genet 2016; 38:252-259. [DOI: 10.1080/13816810.2016.1210651] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Markus N. Preising
- Department of Ophthalmology, Justus-Liebig University Giessen, Giessen, Germany
| | - Michaela Abura
- Department of Ophthalmology, Justus-Liebig University Giessen, Giessen, Germany
| | - Melanie Jäger
- Department of Ophthalmology, Justus-Liebig University Giessen, Giessen, Germany
| | - Klaus-Heiko Wassill
- Department of Ophthalmology, Justus-Liebig University Giessen, Giessen, Germany
| | - Birgit Lorenz
- Department of Ophthalmology, Justus-Liebig University Giessen, Giessen, Germany
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Palmer DN. The relevance of the storage of subunit c of ATP synthase in different forms and models of Batten disease (NCLs). Biochim Biophys Acta Mol Basis Dis 2015; 1852:2287-91. [PMID: 26093153 DOI: 10.1016/j.bbadis.2015.06.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Accepted: 06/14/2015] [Indexed: 11/27/2022]
Abstract
The discoveries of specific protein storage in the NCLs, particularly of subunit c of ATP synthase in most, and the sphingolipid activator proteins, SAPs or saposins A and D in CLN1, CLN10 and an unassigned form are reviewed. The subunit c stored in the relevant NCLs is the complete mature molecule including an unusual modification found only in animal species, trimethylation of its lysine-43. Because of its strongly hydrophobic and lipid-like properties subunit c is easily overlooked or incorrectly described. This is becoming more of a problem as subunit c is not detected in standard proteomic investigations. Methods are reviewed that allow its unequivocal characterisation. Subunit c storage and cellular storage body accumulation do not cause the neuropathology characteristic of these diseases. The function of the trimethyl group on lysine-43 of subunit c is considered, along with some indications of where its normal turnover may be disrupted in the NCLs.
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Affiliation(s)
- David N Palmer
- Molecular Biosciences, Faculty of Agriculture and Life Sciences, Lincoln University, PO Box 85084, Lincoln 7647, New Zealand; BARN (www.BARN.org.nz).
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Cooper JD, Tarczyluk MA, Nelvagal HR. Towards a new understanding of NCL pathogenesis. Biochim Biophys Acta Mol Basis Dis 2015; 1852:2256-61. [PMID: 26026924 DOI: 10.1016/j.bbadis.2015.05.014] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 05/20/2015] [Accepted: 05/21/2015] [Indexed: 01/29/2023]
Abstract
The Neuronal Ceroid Lipofuscinoses (NCLs, Batten disease) are a group of inherited neurodegenerative disorders that have been traditionally grouped together on the basis of certain shared clinical and pathological features. However, as the number of genes that appear to cause new forms of NCL continues to grow, it is timely to reassess our understanding of the pathogenesis of these disorders and what groups them together. The various NCL subtypes do indeed share features of a build-up of autofluorescent storage material, progressive neuron loss and activation of the innate immune system. The characterisation of animal models has highlighted the selective nature of neuron loss and its intimate relationship with glial activation, rather than the generalised build-up of storage material. More recent data provide evidence for the pathway-dependent nature of pathology, the contribution of glial dysfunction, and the involvement of new brain regions previously thought to be unaffected, and it is becoming apparent that pathology extends beyond the brain. These data have important implications, not just for therapy, but also for our understanding of these disorders. However, looking beneath these broadly similar pathological themes evidence emerges for marked differences in the nature and extent of these events in different forms of NCL. Indeed, given the widely different nature of the mutated gene products it is perhaps more surprising that these disorders resemble each other as much as they do. Such data raise the question whether we should rethink the collective grouping of these gene deficiencies together, or whether it would be better to consider them as separate entities. This article is part of a Special Issue entitled: Current Research on the Neuronal Ceroid Lipofuscinoses (Batten Disease).
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Affiliation(s)
- Jonathan D Cooper
- Pediatric Storage Disorders Laboratory (PSDL), Department of Basic and Clinical Neuroscience, King's College London, Institute of Psychiatry, Psychology & Neuroscience, James Black Centre, 125 Coldharbour Lane, London SE5 9NU, UK.
| | - Marta A Tarczyluk
- Pediatric Storage Disorders Laboratory (PSDL), Department of Basic and Clinical Neuroscience, King's College London, Institute of Psychiatry, Psychology & Neuroscience, James Black Centre, 125 Coldharbour Lane, London SE5 9NU, UK
| | - Hemanth R Nelvagal
- Pediatric Storage Disorders Laboratory (PSDL), Department of Basic and Clinical Neuroscience, King's College London, Institute of Psychiatry, Psychology & Neuroscience, James Black Centre, 125 Coldharbour Lane, London SE5 9NU, UK
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6
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Di Guardo G. Lipofuscin, lipofuscin-like pigments and autofluorescence. Eur J Histochem 2015; 59:2485. [PMID: 25820564 PMCID: PMC4378218 DOI: 10.4081/ejh.2015.2485] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2015] [Revised: 01/26/2015] [Accepted: 01/27/2015] [Indexed: 12/25/2022] Open
Abstract
A brief overview is here provided on lipofuscin and lipofuscin-like substances, with particular reference to their biological significance as well as to their cellular origin and pathophysiological role. Special emphasis is also placed on the mutual relationships between lipofuscin and lipofuscin-like lipopigments on one side, and cell autofluorescence on the other.
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Croce AC, Bottiroli G. Autofluorescence spectroscopy and imaging: a tool for biomedical research and diagnosis. Eur J Histochem 2014; 58:2461. [PMID: 25578980 PMCID: PMC4289852 DOI: 10.4081/ejh.2014.2461] [Citation(s) in RCA: 287] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 12/04/2014] [Indexed: 12/18/2022] Open
Abstract
Native fluorescence, or autofluorescence (AF), consists in the emission of light in the UV-visible, near-IR spectral range when biological substrates are excited with light at suitable wavelength. This is a well-known phenomenon, and the strict relationship of many endogenous fluorophores with morphofunctional properties of the living systems, influencing their AF emission features, offers an extremely powerful resource for directly monitoring the biological substrate condition. Starting from the last century, the technological progresses in microscopy and spectrofluorometry were convoying attention of the scientific community to this phenomenon. In the future, the interest in the autofluorescence will certainly continue. Current instrumentation and analytical procedures will likely be overcome by the unceasing progress in new devices for AF detection and data interpretation, while a progress is expected in the search and characterization of endogenous fluorophores and their roles as intrinsic biomarkers.
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Affiliation(s)
- A C Croce
- Institute of Molecular Genetics of the National Research Council, University of Pavia.
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A murine model of variant late infantile ceroid lipofuscinosis recapitulates behavioral and pathological phenotypes of human disease. PLoS One 2013; 8:e78694. [PMID: 24223841 PMCID: PMC3815212 DOI: 10.1371/journal.pone.0078694] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Accepted: 09/24/2013] [Indexed: 01/07/2023] Open
Abstract
Neuronal ceroid lipofuscinoses (NCLs; also known collectively as Batten Disease) are a family of autosomal recessive lysosomal storage disorders. Mutations in as many as 13 genes give rise to ∼10 variants of NCL, all with overlapping clinical symptomatology including visual impairment, motor and cognitive dysfunction, seizures, and premature death. Mutations in CLN6 result in both a variant late infantile onset neuronal ceroid lipofuscinosis (vLINCL) as well as an adult-onset form of the disease called Type A Kufs. CLN6 is a non-glycosylated membrane protein of unknown function localized to the endoplasmic reticulum (ER). In this study, we perform a detailed characterization of a naturally occurring Cln6 mutant (Cln6nclf) mouse line to validate its utility for translational research. We demonstrate that this Cln6nclf mutation leads to deficits in motor coordination, vision, memory, and learning. Pathologically, we demonstrate loss of neurons within specific subregions and lamina of the cortex that correlate to behavioral phenotypes. As in other NCL models, this model displays selective loss of GABAergic interneuron sub-populations in the cortex and the hippocampus with profound, early-onset glial activation. Finally, we demonstrate a novel deficit in memory and learning, including a dramatic reduction in dendritic spine density in the cerebral cortex, which suggests a reduction in synaptic strength following disruption in CLN6. Together, these findings highlight the behavioral and pathological similarities between the Cln6nclf mouse model and human NCL patients, validating this model as a reliable format for screening potential therapeutics.
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NCL disease mechanisms. Biochim Biophys Acta Mol Basis Dis 2013; 1832:1882-93. [DOI: 10.1016/j.bbadis.2013.05.014] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2012] [Revised: 05/08/2013] [Accepted: 05/09/2013] [Indexed: 01/13/2023]
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Use of model organisms for the study of neuronal ceroid lipofuscinosis. Biochim Biophys Acta Mol Basis Dis 2013; 1832:1842-65. [PMID: 23338040 DOI: 10.1016/j.bbadis.2013.01.009] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 01/07/2013] [Accepted: 01/08/2013] [Indexed: 12/26/2022]
Abstract
Neuronal ceroid lipofuscinoses are a group of fatal progressive neurodegenerative diseases predominantly affecting children. Identification of mutations that cause neuronal ceroid lipofuscinosis, and subsequent functional and pathological studies of the affected genes, underpins efforts to investigate disease mechanisms and identify and test potential therapeutic strategies. These functional studies and pre-clinical trials necessitate the use of model organisms in addition to cell and tissue culture models as they enable the study of protein function within a complex organ such as the brain and the testing of therapies on a whole organism. To this end, a large number of disease models and genetic tools have been identified or created in a variety of model organisms. In this review, we will discuss the ethical issues associated with experiments using model organisms, the factors underlying the choice of model organism, the disease models and genetic tools available, and the contributions of those disease models and tools to neuronal ceroid lipofuscinosis research. This article is part of a Special Issue entitled: The Neuronal Ceroid Lipofuscinoses or Batten Disease.
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Penzkofer A, Stierl M, Hegemann P, Kateriya S. Absorption and fluorescence characteristics of photo-activated adenylate cyclase nano-clusters from the amoeboflagellate Naegleria gruberi NEG-M strain. Chem Phys 2012. [DOI: 10.1016/j.chemphys.2011.09.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
Mutant GBA was found recently to be the most prevalent risk factor for familial parkinsonism. The two diseases do not share common symptoms and there is no direct pathway to explain the mechanism by which GBA mutations can confer the risk. Increased burden on the degradative pathway caused by defective glucocerebrosidase, or toxic side effects of glycosylated lipids accumulation were proposed to explain brain damage. Both hypotheses are not sufficient to explain the linkage. In order to develop a more inclusive theory we introduced into the model the prion theory and the second hit. Other possibilities are also brought into consideration.
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Affiliation(s)
- Ehud Goldin
- Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD 20892-3708, USA.
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Glial fibrillary acidic protein is elevated in the lysosomal storage disease classical late-infantile neuronal ceroid lipofuscinosis, but is not a component of the storage material. Biochem J 2010; 428:355-62. [PMID: 20370715 DOI: 10.1042/bj20100128] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Classical late-infantile neuronal ceroid lipofuscinosis (LINCL) is a fatal neurodegenerative disease of children caused by mutations in TPP1, the gene encoding the lysosomal protease tripeptidyl peptidase 1. LINCL is characterized by lysosomal accumulation of storage material of which only a single protein component, subunit c of mitochondrial ATP synthase, has been well established to date. Identification of other protein constituents of the storage material could provide useful insights into the pathophysiology of disease and the natural substrates for TPP1. We have therefore initiated a proteomic analysis of storage material in brain from a LINCL mouse model. One protein, GFAP (glial fibrillary acidic protein), was found to be elevated in the LINCL mice compared with normal controls in both isolated storage bodies and a lysosome-enriched subcellular fraction that contains storage material. To determine whether GFAP accumulates within the lysosome in LINCL, we examined its intracellular distribution using subcellular fractionation and morphological methods. These experiments demonstrate that GFAP is not a component of the storage material in LINCL, suggesting that reports of GFAP storage in other NCLs may need to be re-examined. A number of other proteins were elevated in the storage material and/or lysosome-enriched fraction from the LINCL mice, but it remains unclear whether these proteins are true constituents of the storage material or, like GFAP, whether they associate with this material upon purification.
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Immune system irregularities in lysosomal storage disorders. Acta Neuropathol 2008; 115:159-74. [PMID: 17924126 DOI: 10.1007/s00401-007-0296-4] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2007] [Revised: 09/11/2007] [Accepted: 09/13/2007] [Indexed: 02/07/2023]
Abstract
Lysosomal storage disorders (LSDs) are genetically inherited diseases characterized by the accumulation of disease-specific biological materials such as proteolipids or metabolic intermediates within the lysosome. The lysosomal compartment's central importance to normal cellular function can be appreciated by examining the various pathologies that arise in LSDs. These disorders are invariably fatal, and many display profound neurological impairment that begins in childhood. However, recent studies have revealed that several LSDs also have irregularities in the function of the immune system. Gaucher disease, mucopolysaccharidosis VII, and alpha-mannosidosis are examples of a subset of LSD patients that are predisposed towards immune suppression. In contrast, GM2 gangliosidosis, globoid cell leukodystrophy, Niemann-Pick disease type C1 and juvenile neuronal ceroid lipofuscinosis are LSDs that are predisposed towards immune system hyperactivity. Antigen presentation and processing by dedicated antigen presenting cells (APCs), secretion of pore-forming perforins by cytotoxic-T lymphocytes, and release of pro-inflammatory mediators by mast cells are among the many crucial immune system functions in which the lysosome plays a central role. Although the relationship between the modification of the lysosomal compartment in LSDs and modulation of the immune system remains unknown, there is emerging evidence for early neuroimmune responses in a variety of LSDs. In this review we bridge biochemical studies on the lysosomal compartment's role in the immune system with clinical data on immune system irregularities in a subset of LSDs.
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Kanaan NM, Kordower JH, Collier TJ. Age-related accumulation of Marinesco bodies and lipofuscin in rhesus monkey midbrain dopamine neurons: relevance to selective neuronal vulnerability. J Comp Neurol 2007; 502:683-700. [PMID: 17436290 DOI: 10.1002/cne.21333] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Parkinson's disease (PD) is characterized by degeneration of nigrostriatal dopamine (DA) neurons. Although aging is a primary risk factor for PD, its role in DA neuron degeneration remains unknown. Neurodegeneration in PD is not uniform throughout the ventral midbrain: the ventral tier of the substantia nigra (vtSN) is most vulnerable, whereas the dorsal tier (dtSN) and ventral tegmental area (VTA) are relatively resistant. We studied young (9-10 years old), middle-aged (14-17 years old), and old-aged (22-29 years old) rhesus monkeys to identify factors potentially underlying selective vulnerability and their association with aging. We focused on markers relevant to the ubiquitin-proteasome (UPS) and lysosome systems. Unbiased stereological counting was performed on tyrosine hydroxylase-positive (TH+) neurons and TH+ neurons containing Marinesco bodies (TH+MB) or lipofuscin (TH+lipo), markers of UPS or lysosomal activity, respectively. TH+ neuron numbers were inversely correlated with advancing age specifically in the vtSN, not the dtSN or VTA. TH intensity decreased throughout the ventral midbrain with increasing age, an effect exacerbated in the vtSN. TH+MB neurons were localized in the vulnerable vtSN of old monkeys. The number of MBs per cell increased with age, and TH intensity of TH+MB neurons decreased in middle age. Conversely, TH+lipo neurons were primarily found in the resistant dtSN and VTA. These data suggest that particular age-related changes localize to DAergic subregions relevant to degenerative patterns in PD. Furthermore, the results begin to characterize the nature of the link between aging and PD, and they support the concept that aged monkeys represent a valuable model for studying specific events preceding PD.
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Affiliation(s)
- Nicholas M Kanaan
- Department of Neurological Sciences, Rush University Medical Center, Chicago, Illinois 60612, USA
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Kay GW, Oswald MJ, Palmer DN. The development and characterisation of complex ovine neuron cultures from fresh and frozen foetal neurons. J Neurosci Methods 2006; 155:98-108. [PMID: 16487596 PMCID: PMC1525139 DOI: 10.1016/j.jneumeth.2006.01.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2005] [Revised: 11/21/2005] [Accepted: 01/06/2006] [Indexed: 10/25/2022]
Abstract
Cultures of ovine cerebral and cerebellar neurons from mid-term sheep foetal brains, 9-15 weeks old, have been established for the first time. These foetal brains are relatively mature, being at similar stages of development as peri and post-natal rodent brains. Cultures were routinely maintained for 3-4 weeks, and longer. Nearly all the cells from the younger foetuses adhered as neurons. The proportion of glial cells increased with age, as did the risk of cultures being overtaken by glial cells. Cultured neurons were bipolar, tripolar and multipolar, similar to the morphologies of neurons in vivo. Older foetuses also yield more complex neurons, notably giant cells. Other properties of the cultured neurons also mimic in vivo observations, including neurite beading, complexity in neurotransmitter class (GABAergic and glutamatergic) and calcium binding protein (calbindin and calretinin) content. Single cell divisions of neurons were observed in younger cultures by time-lapse photography and the occurrence of telophase nuclei. The advantage of the high yield of genetically identical cells obtained from a single sheep foetus, 150 million, was extended by cryopreservation of neurons after snap freezing, and later culture. These cultures showed the same characteristics as cultures from the freshly plated cells.
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Affiliation(s)
| | | | - David N. Palmer
- * Correspondence to: Dr D N Palmer, Agricultural and Life Sciences Division, PO Box 84, Lincoln University, Canterbury, New Zealand, Tel.: +64-3-325-2811, Fax : +64-3-325-3851, E-mail:
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Chen R, Fearnley IM, Palmer DN, Walker JE. Lysine 43 is trimethylated in subunit C from bovine mitochondrial ATP synthase and in storage bodies associated with batten disease. J Biol Chem 2004; 279:21883-7. [PMID: 15010464 DOI: 10.1074/jbc.m402074200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The hydrophobic membrane protein, subunit c, has been isolated from ATP synthase purified from bovine heart mitochondria. It has also been obtained from lysosomal storage bodies associated with ceroid lipofuscinosis from ovine liver and from human brain tissue of a victim of Batten disease. It is likely that the lysosomal protein has originated from the mitochondrion. These samples have been characterized by mass spectrometric methods. Irrespective of its source, subunit c has an intact molecular mass of 7650 Da, 42 Da greater than the value calculated from the amino acid sequence, and the protein has been modified post-translationally. In all three samples, the modification is associated with lysine 43, which lies in a polar loop region linking the two transmembrane alpha-helices of the protein. This residue is conserved throughout vertebrate sequences. The additional mass arises from trimethylation and not acetylation at the epsilon-N-position of the residue. These experiments show that the post-translational modification of subunit c is not, as has been suggested, an abnormal phenomenon associated with the etiology of Batten disease and ceroid lipofucinoses. Evidently, it occurs either before or during import of the protein into mitochondria or at a mitochondrial location after completion of the import process. The function of the trimethyllysine residue in the assembled ATP synthase complex is obscure. The residue and the modification are not conserved in all ATP synthases, and their role in the assembly and (or) functioning of the enzyme appear to be confined to higher organisms.
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Affiliation(s)
- Ruming Chen
- Medical Research Council Dunn Human Nutrition Unit, Wellcome Trust/Medical Research Council Building, Hills Road, Cambridge, CB2 2XY, United Kingdom
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