These data are from the brains (amygdala and hippocampus) of mice originally derived from a cross between C57BL/6J and A/J inbred strains. We used short-term selection to produce outbred mouse lines with differences in contextual fear conditioning, which is a measure of fear learning. We selected for a total of 4 generations. Fear learning differed in the selected lines and this difference was stronger with each successive generation of selection. We identified several QTLs for the selection response, including a highly significant QTL at the tyr locus (p < 9.6(-10)). We used Affymetrix microarrays to identify many differentially expressed genes in the amygdala and hippocampus of mice from the final generation of selection. Amygdala and hippocampus samples were rapidly dissected out of experimentally nave mice from each selected line. Three samples were pooled and hybridized to each array. Experimentally nave mice were used because the behavior of the mice can be reliably a nticipated due to their lineage. Thus these gene expression differences are not due to the response to human handling, foot shock or fear-inducing conditioned stimuli. We have a second similar study that focuses on a different selected population that was based on C57BL/6J and DBA/2J mice (see GES4035).
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View SamplesThese data are from the brains (amygdala and hippocampus) of mice originally derived from a cross between C57BL/6J and DBA/2J inbred strains. We used short-term selection to produce outbred mouse lines with differences in contextual fear conditioning, which is a measure of fear learning. We selected for a total of 4 generations. Fear learning differed in the selected lines and this difference was stronger with each successive generation of selection. These mice also showed differences for measures of anxiety-like behavior, but were not different for tests of non-fear motivated learning, suggesting that selection altered alleles that are specifically involved in emotional behaviors. We identified several QTLs for the selection response. We used Affymetrix microarrays to identify differentially expressed genes in the amygdala and hippocampus of mice from the final generation of selection. Amygdala and hippocampus samples were rapidly dissected out of experimentally nave mice f rom each selected line. Three samples were pooled and hybridized to each array. Experimentally nave mice were used because the behavior of the mice can be reliably anticipated due to their lineage. Thus, these gene expression differences are not due to the response to human handling, foot shock or fear-inducing conditioned stimuli. We have a second similar study that focuses on a different selected population that was based on C57BL/6J and A/J mice (see GES4034).
Selection for contextual fear conditioning affects anxiety-like behaviors and gene expression.
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View SamplesParkinsons disease (PD) and Dementia with Lewy bodies (DLB) are the two most common examples of synucleinopathies, i.e. human disorders that display intracellular deposition of the Alpha-synuclein (aSYN) protein. The two forms of aSYN deposits, intracellular Lewy bodies and Lewy neurites, are in the PD brain primarily found in the substantia nigra whereas in DLB brains they are diffusely spread in cortical and limbic areas. We are currently analyzing the protective effects on aSYN pathology by the molecular chaperone hsp70 in mice overexpressing wildtype human aSYN. Moreover, transgenic mice overexpressing hsp70 have been cross-bred with the aSYN mouse line. Intriguingly, the aSYN / hsp70 double transgenics display a pronounced reduction in biochemically assessed aSYN aggregation. Gene expression of these mice will not only provide insight into the disease mechanisms of aSYN pathology but its prevention by the overexpression of hsp70, leading to new potential avenues of treatment.
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View SamplesThe lack of axonal growth after injury in the adult central nervous system (CNS) is partly due to the presence of growth-inhibitory molecules associated with myelin and the intrinsic growth-state of the injured neurons. To date, three inhibitors have been identified in myelin: Myelin- Associated Glycoprotein (MAG), Nogo A, and Oligodendrocyte-Myelin glycoprotein (OMgp). These three proteins all appear to be located in the periaxonal surface of the myelin membrane placing them in an optimal location to mediate axon-glial interaction. In addition, the three proteins have been shown to bind the same neuronal receptor, known as the Nogo-66 receptor (NgR). It has been hypothesized that inhibition of NgR may be a strategy to increase regeneration, plasticity and functional recovery of the lesioned central nervous system. Strong NgR mRNA expression is observed in the hippocampal pyramidal cell layers (CA1-3) and the granular layer of the dentate gyrus. It has been shown that animals exposed to entorhinal lesions show a biphasic regulation of NgR in the hippocampus, suggesting a tightly regulated mechanism mediated by this receptor. We have access to a transgenic model to over-express NgR in forebrain hippocampal neurons. Preliminary results have shown a phenotypic response in behavior and some molecular markers, as result of NgR overexpression. Knowledge of what genes are reacting in this novel transgenic model may provide insights into what pathways are affected by NgR to control synaptic plasticity in normal animals and during injury.
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View SamplesWe are examining the genes that control initiation and progression of murine medulloblastomas that result from loss of patched. Approximately 25% of human medulloblastomas have mutations in patched or in other elements of the sonic hedgehog pathway. However, the cells from which these tumors originate (neural progenitors or stem cells), the cells that are responsible for tumor propagation (cancer stem cells), and the genes that are required for tumor progression are poorly understood. To address these questions, we have developed conditional patched knockout mice in which the gene is deleted in neural stem cells or progenitors. In addition, we have isolated a population of tumor-propagating cells from these tumors. By studying these models we will gain insight into the mechanisms of tumorigenesis and identify new targets for therapy.
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View SamplesThe goals of this research are three-fold: (i) One is to identify genetic changes associated with tumorgenesis that interfere with the ability of transformed glial cells to differentiate. This is connected with (ii) our analysis of the regulation of differentiation in normal glial progentor cells, as only by understanding this in normal cells can we understand what is occurring when differentiation fails in transformed versions of the same cells. (iii) The third is to identify the molecular basis for the greater resistance of transformed glial progenitor cells to chemotherapeutic agents as compared with normal glial progenitor cells. Thus, analysis of the populations provided will yield data crucial to two of our central areas of research, as awarded by NINDS in "Oligodendrocytes & precursors: toxicity of chemotherapy" (5R01NS044701), and "Low-level toxicant perturbation of neural cell function" (1R01ES012708).
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View SamplesInfantile neuronal ceroid lipofuscinosis (aka infantile Batten disease) is a severe neurodegenerative disorder of early childhood characterized by cortical atrophy, blindness and seizures, leading to premature death in the first decade. The disorder is caused by deficiency in a soluble lysosomal enzyme, palmitoyl protein thioesterase-1 (PPT1). PPT1 knockout mice faithfully reproduce the features of the human disease, with motor deterioration, blindness, seizures, and death before 10 months of age. The progression of events leading from enzyme deficiency to organ failure is poorly defined. The neuronal ceroid lipofuscinoses are of particular interest because of the similarities between the accumulated material and lipofuscin that is associated with normal aging.
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View SamplesHypoxic-ischemic (HI) injury in the developing brain is a common cause of disability in children, and there are no effective treatments at this time. Erythropoietin (EPO) has recently gained interest as a neuroprotective drug, and EPO and its receptor are expressed within the central nervous system. We have recently shown that pretreatment with EPO markedly reduced brain injury caused by unilateral hypoxic-ischemic insult in 7 day old mice. EPO did not reduce early signs of neuronal injury at 6 hours, but significantly protected the neonatal brain when assessed 24 hours and 7 days after HI. The mechanism of this delayed protection is unclear, but is thought to involve transcription of neuroprotective genes, possibly subsequent to activation of NFkB. By comparing gene expression in EPO- and vehicle- (VEH) treated mice after HI, we should gain insight into the mechanisms underlying the neuroprotective effects of EPO and may identify additional targets for therapeutic interventions.
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View SamplesIn our original grant we proposed to use the NR3B-null mouse model to study the role of NR3B subunit in motor neuron function. We have now successfully generated NR3B null mice. Interestingly, NR3B-null mice invariably die at age P4-P8. Our preliminary examination indicates that the motor strength of these mice is severely impaired prior to death. As we continue to explore the cause of death in NR3B null mice, we propose to conduct gene profiling experiments to search for transcription changes in the brain related to ablation of the NR3B gene. We would like to use the facility provided by the NINDS/NIMH Microarray Consortium to identify true outlier genes that show abnormal expression patterns in these mice. Analysis of these outlier genes will help to identify changes in networks and pathways that may cause the death of NR3B-null mice. These studies will further help to elucidate the functional role of NR3B in motor neurons.
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View SamplesIn our original grant we proposed to use the NR3B-null mouse model to study the role of NR3B subunit in motor neuron function. We have now successfully generated NR3B null mice. Interestingly, NR3B-null mice invariably die at age P4-P8. Our preliminary examination indicates that the motor strength of these mice is severely impaired prior to death. As we continue to explore the cause of death in NR3B null mice, we propose to conduct gene profiling experiments to search for transcription changes in the brain related to ablation of the NR3B gene. We have used the facility provided by the NINDS/NIMH Microarray Consortium to identify genes that show abnormal expression patterns in these mice. We would like to compare these changes with that opccured in SOD1 mice, a mouse model of motor neuron diseases. Analysis of these genes will help to identify changes in networks and pathways that may cause the death of NR3B-null mice. These studies will further help to elucidate the functional role of NR3B in motor neurons.
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