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Apuschkin M, Stilling S, Rahbek-Clemmensen T, Sørensen G, Fortin G, Herborg Hansen F, Eriksen J, Trudeau LE, Egerod K, Gether U, Rickhag M. A novel dopamine transporter transgenic mouse line for identification and purification of midbrain dopaminergic neurons reveals midbrain heterogeneity. Eur J Neurosci 2015; 42:2438-54. [PMID: 26286107 DOI: 10.1111/ejn.13046] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Revised: 08/12/2015] [Accepted: 08/13/2015] [Indexed: 01/29/2023]
Abstract
Midbrain dopaminergic (DAergic) neurons are a heterogeneous cell group, composed of functionally distinct cell populations projecting to the basal ganglia, prefrontal cortex and limbic system. Despite their functional significance, the midbrain population of DAergic neurons is sparse, constituting only 20 000-30 000 neurons in mice, and development of novel tools to identify these cells is warranted. Here, a bacterial artificial chromosome mouse line [Dat1-enhanced green fluorescent protein (eGFP)] from the Gene Expression Nervous System Atlas (GENSAT) that expresses eGFP under control of the dopamine transporter (DAT) promoter was characterized. Confocal microscopy analysis of brain sections showed strong eGFP signal reporter in midbrain regions and striatal terminals that co-localized with the DAergic markers DAT and tyrosine hydroxylase (TH). Thorough quantification of co-localization of the eGFP reporter signal with DAT and TH in the ventral midbrain showed that a vast majority of eGFP-expressing neurons are DAergic. Importantly, expression profiles also revealed DAergic heterogeneity when comparing substantia nigra and ventral tegmental area. Dat1-eGFP mice showed neither change in synaptosomal DA uptake nor altered levels of DAT and TH in both striatum and midbrain. No behavioural difference between Dat1-eGFP and wild-type was found, suggesting that the strain is not aberrant. Finally, cell populations highly enriched in DAergic neurons can be obtained from postnatal mice by fluorescence-activated cell sorting and the sorted neurons can be cultured in vitro. The current investigation demonstrates that eGFP expression in this mouse line is selective for DAergic neurons, suggesting that the Dat1-eGFP mouse strain constitutes a promising tool for delineating new aspects of DA biology.
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Affiliation(s)
- Mia Apuschkin
- Department of Neuroscience and Pharmacology, Molecular Neuropharmacology and Genetics Laboratory, Lundbeck Foundation Center for Biomembranes in Nanomedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Sara Stilling
- Department of Neuroscience and Pharmacology, Molecular Neuropharmacology and Genetics Laboratory, Lundbeck Foundation Center for Biomembranes in Nanomedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Troels Rahbek-Clemmensen
- Department of Neuroscience and Pharmacology, Molecular Neuropharmacology and Genetics Laboratory, Lundbeck Foundation Center for Biomembranes in Nanomedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Gunnar Sørensen
- Department of Neuroscience and Pharmacology, Molecular Neuropharmacology and Genetics Laboratory, Lundbeck Foundation Center for Biomembranes in Nanomedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Neuroscience and Pharmacology, Laboratory of Neuropsychiatry, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Guillaume Fortin
- Department of Pharmacology and Groupe de Recherche sur le Système Nerveux Central, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada
| | - Freja Herborg Hansen
- Department of Neuroscience and Pharmacology, Molecular Neuropharmacology and Genetics Laboratory, Lundbeck Foundation Center for Biomembranes in Nanomedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jacob Eriksen
- Department of Neuroscience and Pharmacology, Molecular Neuropharmacology and Genetics Laboratory, Lundbeck Foundation Center for Biomembranes in Nanomedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Louis-Eric Trudeau
- Department of Pharmacology and Groupe de Recherche sur le Système Nerveux Central, Faculty of Medicine, Université de Montréal, Montréal, Québec, Canada
| | - Kristoffer Egerod
- Department of Neuroscience and Pharmacology, Molecular Pharmacology Laboratory, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Section for Metabolic Receptology and Enteroendocrinology, Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Ulrik Gether
- Department of Neuroscience and Pharmacology, Molecular Neuropharmacology and Genetics Laboratory, Lundbeck Foundation Center for Biomembranes in Nanomedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Mattias Rickhag
- Department of Neuroscience and Pharmacology, Molecular Neuropharmacology and Genetics Laboratory, Lundbeck Foundation Center for Biomembranes in Nanomedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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Cruz FC, Koya E, Guez-Barber DH, Bossert JM, Lupica CR, Shaham Y, Hope BT. New technologies for examining the role of neuronal ensembles in drug addiction and fear. Nat Rev Neurosci 2013; 14:743-54. [PMID: 24088811 DOI: 10.1038/nrn3597] [Citation(s) in RCA: 183] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Correlational data suggest that learned associations are encoded within neuronal ensembles. However, it has been difficult to prove that neuronal ensembles mediate learned behaviours because traditional pharmacological and lesion methods, and even newer cell type-specific methods, affect both activated and non-activated neurons. In addition, previous studies on synaptic and molecular alterations induced by learning did not distinguish between behaviourally activated and non-activated neurons. Here, we describe three new approaches--Daun02 inactivation, FACS sorting of activated neurons and Fos-GFP transgenic rats--that have been used to selectively target and study activated neuronal ensembles in models of conditioned drug effects and relapse. We also describe two new tools--Fos-tTA transgenic mice and inactivation of CREB-overexpressing neurons--that have been used to study the role of neuronal ensembles in conditioned fear.
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Affiliation(s)
- Fabio C Cruz
- Intramural Research Program, National Institute on Drug Abuse-National Institutes of Health, 251 Bayview Boulevard, Baltimore, Maryland 21224, USA
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Karsten SL, Kudo LC, Bragin AJ. Use of peripheral blood transcriptome biomarkers for epilepsy prediction. Neurosci Lett 2011; 497:213-7. [PMID: 21419828 DOI: 10.1016/j.neulet.2011.03.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2010] [Revised: 03/06/2011] [Accepted: 03/07/2011] [Indexed: 12/13/2022]
Abstract
There are currently no predictive methods to identify patients who suffered an initial brain injury and are at high risk of developing chronic epilepsy. Consequently, treatments aimed at epilepsy prevention that would target the underlying epileptogenic process are neither available nor being developed. After a brain injury or any other initial precipitating event (IPE) to the development of epilepsy, pathological changes may occur in forms of inflammation, damage in the blood brain barrier, neuron loss, gliosis, axon sprouting, etc., in multiple brain areas. Recent studies provide connections between various kinds of brain pathology and alterations in the peripheral blood transcriptome. In this review we discuss the possibility of using peripheral blood transcriptome biomarkers for the detection of epileptogenesis and consequently, subjects at high risk of developing epilepsy.
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Affiliation(s)
- Stanislav L Karsten
- Division of Neuroscience, Department of Neurology, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA 90504, USA.
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Kim K, Zakharkin SO, Allison DB. Expectations, validity, and reality in gene expression profiling. J Clin Epidemiol 2010; 63:950-9. [PMID: 20579843 DOI: 10.1016/j.jclinepi.2010.02.018] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2009] [Revised: 02/09/2010] [Accepted: 02/11/2010] [Indexed: 01/11/2023]
Abstract
OBJECTIVE To provide a critical overview of gene expression profiling methodology and discuss areas of future development. RESULTS Gene expression profiling has been used extensively in biological research and has resulted in significant advances in the understanding of the molecular mechanisms of complex disorders, including cancer, heart disease, and metabolic disorders. However, translating this technology into genomic medicine for use in diagnosis and prognosis faces many challenges. In addition, gene expression profile analysis is frequently controversial, because its conclusions often lack reproducibility and claims of effective dissemination into translational medicine have, in some cases, been remarkably unjustified. In the last decade, a large number of methodological and technical solutions have been offered to overcome the challenges. STUDY DESIGN AND SETTING We consider the strengths, limitations, and appropriate applications of gene expression profiling techniques, with particular reference to the clinical relevance. CONCLUSION Some studies have demonstrated the ability and clinical utility of gene expression profiling for use as diagnostic, prognostic, and predictive molecular markers. The challenges of gene expression profiling lie with the standardization of analytic approaches and the evaluation of the clinical merit in broader heterogeneous populations by prospective clinical trials.
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Affiliation(s)
- Kyoungmi Kim
- Division of Biostatistics, Department of Public Health Sciences, University of California, Davis, CA 95616, USA.
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Kudo LC, Parfenova L, Vi N, Lau K, Pomakian J, Valdmanis P, Rouleau GA, Vinters HV, Wiedau-Pazos M, Karsten SL. Integrative gene-tissue microarray-based approach for identification of human disease biomarkers: application to amyotrophic lateral sclerosis. Hum Mol Genet 2010; 19:3233-53. [PMID: 20530642 DOI: 10.1093/hmg/ddq232] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Advances in genomics and proteomics permit rapid identification of disease-relevant genes and proteins. Challenges include biological differences between animal models and human diseases, high discordance between DNA and protein expression data and a lack of experimental models to study human complex diseases. To overcome some of these limitations, we developed an integrative approach using animal models, postmortem human material and a combination of high-throughput microarray methods to identify novel molecular markers of amyotrophic lateral sclerosis (ALS). We used laser capture microdissection coupled with microarrays to identify early transcriptome changes occurring in spinal cord motor neurons or surrounding glial cells. Two models of familial motor neuron disease, SOD1(G93A) and TAU(P301L), transgenic mice were used at the presymptomatic stage. Identified gene expression changes were predominantly model-specific. However, several genes were regulated in both models. The relevance of identified genes as clinical biomarkers was tested in the peripheral blood transcriptome of presymptomatic SOD1(G93A) animals using custom-designed ALS microarray. To confirm the relevance of identified genes in human sporadic ALS (SALS), selected corresponding protein products were examined by high-throughput immunoassays using tissue microarrays constructed from human postmortem spinal cord tissues. Genes that were identified by these experiments and located within a linkage region associated with familial ALS/frontotemporal dementia were sequenced in several families. This large-scale gene and protein expression study pointing to distinct molecular mechanisms of TAU- and SOD1-induced motor neuron degeneration identified several new SALS-relevant proteins (CNGA3, CRB1, OTUB2, MMP14, SLK, DDX58, RSPO2) and putative blood biomarkers, including Nefh, Prph and Mgll.
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Affiliation(s)
- Lili C Kudo
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
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Tissue compartment analysis for biomarker discovery by gene expression profiling. PLoS One 2009; 4:e7779. [PMID: 19901995 PMCID: PMC2771357 DOI: 10.1371/journal.pone.0007779] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2009] [Accepted: 10/16/2009] [Indexed: 12/02/2022] Open
Abstract
Background Although high throughput technologies for gene profiling are reliable tools, sample/tissue heterogeneity limits their outcomes when applied to identify molecular markers. Indeed, inter-sample differences in cell composition contribute to scatter the data, preventing detection of small but relevant changes in gene expression level. To date, attempts to circumvent this difficulty were based on isolation of the different cell structures constituting biological samples. As an alternate approach, we developed a tissue compartment analysis (TCA) method to assess the cell composition of tissue samples, and applied it to standardize data and to identify biomarkers. Methodology/Principal Findings TCA is based on the comparison of mRNA expression levels of specific markers of the different constitutive structures in pure isolated structures, on the one hand, and in the whole sample on the other. TCA method was here developed with human kidney samples, as an example of highly heterogeneous organ. It was validated by comparison of the data with those obtained by histo-morphometry. TCA demonstrated the extreme variety of composition of kidney samples, with abundance of specific structures varying from 5 to 95% of the whole sample. TCA permitted to accurately standardize gene expression level amongst >100 kidney biopsies, and to identify otherwise imperceptible molecular disease markers. Conclusions/Significance Because TCA does not require specific preparation of sample, it can be applied to all existing tissue or cDNA libraries or to published data sets, inasmuch specific operational compartments markers are available. In human, where the small size of tissue samples collected in clinical practice accounts for high structural diversity, TCA is well suited for the identification of molecular markers of diseases, and the follow up of identified markers in single patients for diagnosis/prognosis and evaluation of therapy efficiency. In laboratory animals, TCA will interestingly be applied to central nervous system where tissue heterogeneity is a limiting factor.
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Sanfilippo syndrome type B, a lysosomal storage disease, is also a tauopathy. Proc Natl Acad Sci U S A 2009; 106:8332-7. [PMID: 19416848 DOI: 10.1073/pnas.0903223106] [Citation(s) in RCA: 102] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Sanfilippo syndrome type B (mucopolysaccharidosis III B, MPS III B) is an autosomal recessive, neurodegenerative disease of children, characterized by profound mental retardation and dementia. The primary cause is mutation in the NAGLU gene, resulting in deficiency of alpha-N-acetylglucosaminidase and lysosomal accumulation of heparan sulfate. In the mouse model of MPS III B, neurons and microglia display the characteristic vacuolation of lysosomal storage of undegraded substrate, but neurons in the medial entorhinal cortex (MEC) display accumulation of several additional substances. We used whole genome microarray analysis to examine differential gene expression in MEC neurons isolated by laser capture microdissection from Naglu(-/-) and Naglu(+/-) mice. Neurons from the lateral entorhinal cortex (LEC) were used as tissue controls. The highest increase in gene expression (6- to 7-fold between mutant and control) in MEC and LEC neurons was that of Lyzs, which encodes lysozyme, but accumulation of lysozyme protein was seen in MEC neurons only. Because of a report that lysozyme induced the formation of hyperphosphorylated tau (P-tau) in cultured neurons, we searched for P-tau by immunohistochemistry. P-tau was found in MEC of Naglu(-/-) mice, in the same neurons as lysozyme. In older mutant mice, it was also seen in the dentate gyrus, an area important for memory. Electron microscopy of dentate gyrus neurons showed cytoplasmic inclusions of paired helical filaments, P-tau aggregates characteristic of tauopathies-a group of age-related dementias that include Alzheimer disease. Our findings indicate that the Sanfilippo syndrome type B should also be considered a tauopathy.
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