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Deborah Young

Publications and source records attributed to Deborah Young.

13 recordsLinked to original sources
PubMed2006

Phosphorylation-dependent degradation of transgenic CREB protein initiated by heterodimerization.

The transcription factor CREB (cyclic AMP response element binding protein) is implicated in diverse brain functions and represents a prospective target in gene therapy for human disorders. However, the transgenic expression and stability of exogenously expressed CREB within the cell remains poorly characterized. Here we found that transient expression of a CREB dominant interfering mutant A-CREB or the inducible cAMP early repressor, ICER, led to the dramatic decrease of exogenously co-expressed CREB in 293 human embryonic kidney cells. Elevation of protein kinase A activity within the cells restored CREB protein levels. A-CREB did not effect the transient expression of a truncated CREB lacking the leucine zipper domain demonstrating a specific effect of heterodimerization on CREB protein stability. Somatic gene transfer into the rat brain using a recombinant adeno-associated virus vector provided robust expression of both transgenic CREB and ICER mRNAs under the control of a constitutive neuron specific enolase (NSE) promoter. In contrast to ICER, the expression of the transgenic CREB mRNA did not result in elevation of CREB protein levels within dentate granule cells of the hippocampus, suggesting its prompt degradation under basal conditions. However, following tetanization of the perforant pathway, which is known to induce CREB phosphorylation, there was a significant increase in the amount of transgenic CREB protein within dentate granule cells. Hence, heterodimerization of unphosphorylated CREB with either A-CREB or ICER triggers CREB protein degradation, whereas phosphorylation prevents CREB from such degradation both in vitro and in vivo.

Animals↗
PubMed2006

Somatic gene transfer of cAMP response element-binding protein attenuates memory impairment in aging rats.

cAMP response element-binding protein (CREB) is important for the formation and facilitation of long-term memory in diverse models. However, to our knowledge, involvement of CREB in age-associated memory impairment has not been reported. Here, we use a recombinant adeno-associated virus vector to obtain stable transgenic expression of CREB as well as the inducible cAMP early repressor (ICER) in the hippocampus of adult rats. In a longitudinal study, we show that somatic gene transfer of both CREB and ICER does not alter long-term memory in young (3-month-old) rats. However, at 15 months of age, the same CREB-transduced rats show significantly better long-term memory in spatial-navigation and passive-avoidance tasks compared with their equally aged control littermates, and a threshold effect is evident. In contrast, the aged ICER-transduced rats demonstrate significantly reduced memory in comparison with the same control group. Hippocampal CREB gene transfer prevented the aging-related decrease in long-term memory found in the control rats. These data suggest that elevation of CREB protein levels in a subset of hippocampal neurons as achieved by somatic cell gene transfer might compensate for general deficits in molecular mechanisms underlying age-related memory loss in rats and, therefore, attenuate long-term-memory impairment during normal aging.

Adenoviridae↗
PubMed2006

Differential actions of NPY on seizure modulation via Y1 and Y2 receptors: evidence from receptor knockout mice.

PURPOSE: Neuropeptide Y (NPY) has been shown to modulate seizure activities. To provide further understanding of the involvement of two of the most abundantly expressed NPY receptors, Y1 and Y2, we assessed the effect of Y1 and Y2 gene deletion on systemic kainic acid-induced seizures. We also examined the effect of rAAV-mediated hippocampal NPY overexpression on seizure susceptibility in these receptor knockout mice. METHODS: Recombinant adeno-associated viral vector overexpressing NPY (rAAV-NPY) or an empty vector control (rAAV-Empty) was injected into the hippocampus of adult C57BL/6-129/SvJ wild-type male mice and mice deficient of Y1 or Y2 receptors on the same background. Four weeks after vector injection, mice were subjected to systemic kainic acid-induced seizures, and the seizure behaviors were scored. RESULTS: The rAAV-mediated hippocampal overexpression of NPY led to a twofold reduction in seizures induced by systemic kainic acid in wild-type mice and Y1 receptor knockout mice but not in mice deficient of Y2 receptors. A differential action by the receptors was observed in the seizure-induced mortality rate, with increased fatality in Y2-/- mice. In addition, although NPY overexpression did not significantly affect the mortality rate in Y2-/- and wild-type mice, it abolished KA-induced mortality in Y1-/-mice. CONCLUSIONS: This study shows for the first time an altered susceptibility to chemically induced seizures in Y1 and Y2 knockout mice and demonstrates a differential seizure modulation mediated by these receptors via a genetic approach.

Animals↗
PubMed2005

A novel role of circadian transcription factor DBP in hippocampal plasticity.

In neurons, a variety of extracellular stimuli are capable of inducing transcriptional events that underlie complex processes ranging from learning to disease. The mechanisms linking these long-lasting cellular modifications to behavior remain to be established. Here, we show by microarray analysis that hippocampal activation of glucagon-like peptide-1 receptor (GLP-1R), which is associated with improved learning and neuroprotection, results in suppression of the transcription factor DBP (albumin D-site-binding protein). Recombinant adeno-associated virus (rAAV) based gene expression of DBP in the hippocampus of adult rats caused upregulation of mRNAs encoding constituents of the molecular clock, and the DBP target gene, pyridoxal kinase. Behaviorally, DBP over expression inhibited spatial learning but not memory, and enhanced susceptibility to kainate-induced seizures. This phenotype was paralleled by the activation of MAP kinase in dendritic regions of hippocampal neurons in vivo. These data suggest that DBP may represent an important transcriptional link between GLP-1R activation and neuroplasticity in the hippocampus.

Animals↗
PubMed2005

AAV-mediated hippocampal expression of short and long Homer 1 proteins differentially affect cognition and seizure activity in adult rats.

Homer proteins mediate molecular rearrangements leading to changes in spine morphology. This points to a role of Homer in learning and memory. Homer 1c features both the ligand binding domain and a coiled-coiled domain for self-multimerization. Homer 1a lacks the coiled-coiled domain. Here, we report a new isoform which we termed 1g, lacking the Homer ligand binding domain. We dissected the functional roles of the individual Homer 1 domains, encoded by Homer 1a, 1c, and 1g, in vivo. Recombinant adeno-associated virus (AAV)-mediated overexpression of these forms in the hippocampus of adult rats has opposing effects on learning behavior. Increased levels of Homer 1a impaired hippocampal-dependent memory, while Homer 1g and 1c slightly enhanced memory performance. Homer 1g induced anxiety. Moreover, AAV-Homer 1a animals showed attenuation of electrographic seizures in a model of status epilepticus. These results suggest that Homer 1 proteins play an active role in behavioral plasticity.

Animals↗
PubMed2005

Restoration of aspartoacylase activity in CNS neurons does not ameliorate motor deficits and demyelination in a model of Canavan disease.

Canavan disease is an early onset leukodystrophy associated with psychomotor retardation, seizures, and premature death. This disorder is caused by mutations in the gene encoding the enzyme aspartoacylase (ASPA). Normally, ASPA is enriched in oligodendrocytes and ASPA deficiency results in elevated levels of its substrate molecule, N-acetylaspartate (NAA), brain edema, and dysmyelination. Using adeno-associated virus, we permanently expressed ASPA in CNS neurons of the tremor rat, a genetic model of Canavan disease, and examined the efficacy of the treatment by monitoring NAA metabolism, myelination, motor behavior, and seizures. Assessment of ASPA protein and enzyme activity in whole brain hemispheres showed restoration to normal levels as long as 6 months after treatment. This finding correlated with a reduction of NAA levels, along with a rescue of the seizure phenotype. However, gross brain pathology, such as dilated ventricles and spongiform vacuolization, was unchanged. Moreover, hypomyelination and motor deficits were not resolved by ASPA gene transfer. Our data suggest that NAA-mediated neuronal hyperexcitation but not oligodendrocyte dysfunction can be compensated for by neuronal ASPA expression.

Amidohydrolases↗
PubMed2004

VEGF links hippocampal activity with neurogenesis, learning and memory.

An enriched environment is associated with hippocampal plasticity, including improved cognitive performance and increased neurogenesis. Here, we show that hippocampal expression of vascular endothelial growth factor (VEGF) is increased by both an enriched environment and performance in a spatial maze. Hippocampal gene transfer of VEGF in adult rats resulted in approximately 2 times more neurogenesis associated with improved cognition. In contrast, overexpression of placental growth factor, which signals through Flt1 but not kinase insert domain protein receptors (KDRs), had negative effects on neurogenesis and inhibited learning, although it similarly increased endothelial cell proliferation. Expression of a dominant-negative mutant KDR inhibited basal neurogenesis and impaired learning. Coexpression of mutant KDR antagonized VEGF-enhanced neurogenesis and learning without inhibiting endothelial cell proliferation. Furthermore, inhibition of VEGF expression by RNA interference completely blocked the environmental induction of neurogenesis. These data support a model in which VEGF, acting through KDR, mediates the effect of the environment on neurogenesis and cognition.

Animals↗
PubMed2004

AAV-mediated gene delivery of BDNF or GDNF is neuroprotective in a model of Huntington disease.

Huntington disease (HD) is a neurodegenerative disorder that results in the progressive loss of GABAergic medium spiny projection neurons in the striatum. Neurotrophic factors have demonstrated neuroprotective actions on striatal neurons, suggesting that increased neurotrophic factor expression may prevent or reduce neuronal loss in the HD brain. We investigated whether enhanced expression of brain-derived neurotrophic factor (BDNF) or glial cell line-derived neurotrophic factor (GDNF), achieved by adeno-associated viral (AAV) vector-mediated gene delivery, could protect striatal neurons in the quinolinic acid (QA) rodent model of HD. Adult Wistar rats received unilateral intrastriatal injections of AAV-BDNF, AAV-GDNF, AAV-GFP, or PBS. Three weeks later, the rats were lesioned with QA, a toxin that induces striatal neuron death by an excitotoxic process. Both AAV-BDNF and AAV-GDNF significantly reduced the loss of both NeuN- and calbindin-immunopositive striatal neurons 2 weeks after lesion compared to controls. AAV-BDNF also provided significant neurotrophic support to NOS-immunopositive striatal interneurons, while AAV-GDNF-treated rats demonstrated significant protection of parvalbumin-immunopositive striatal interneurons compared to controls. These results indicate that AAV-mediated gene transfer of BDNF or GDNF into the striatum provides neuronal protection in a rodent model of HD.

Animals↗
PubMed2003

Identification and distribution of aspartoacylase in the postnatal rat brain.

Aspartoacylase metabolizes N-acetylaspartic acid to produce L-aspartate and acetate. An aspartoacylase deficiency in humans is responsible for Canavan disease, a lethal autosomal recessive leukodystrophy. The role of aspartoacylase in the mammalian brain is unclear. Here we have generated and characterized a highly specific polyclonal antibody against aspartoacylase which recognizes a 37 kDa monomer and a dimer in normal but not in aspartoacylase-deficient rat tissue. Aspartoacylase protein expression sharply increases at P14, peaks at P28 and plateaus thereafter. Biochemical analysis reveals immunoreactivity in cytosolic but not in membrane fractions. Histologically, most abundant expression was observed in white matter tracts and thalamus. On the cellular level, aspartoacylase immunoreactivity is restricted to oligodendrocyte somata in both white and gray matter.

Aging↗
PubMed2003

Recombinant AAV-mediated expression of galanin in rat hippocampus suppresses seizure development.

Galanin, a 29- or 30-amino acid neuropeptide, has been implicated in the modulation of seizures. In this study, we constructed a recombinant adeno-associated viral (AAV) vector to constitutively over-express galanin (AAV-GAL). The vector mediated efficient transduction of HEK 293 cells in vitro and robust galanin expression in vivo when injected into the rat dorsal hippocampus. Rats were administered kainic acid intrahippocampally 2.5 months following AAV-GAL or empty vector (AAV-Empty) injection to study the effect of vector-mediated galanin over-expression on seizures. AAV-GAL-injected rats showed a decreased number of seizure episodes and total time spent in seizures compared to AAV-Empty rats, despite similar latencies to development of the first EEG seizure and similar levels of neuronal damage in the CA3 region for both groups. These data show that recombinant AAV mediates strong and stable over-expression of galanin when injected into the rat hippocampus resulting in a significant anticonvulsive effect. The seizure suppression effect of galanin expression in the hippocampus by viral vectors may lead to novel therapeutic strategies for the treatment and management of intractable seizures with focal onset such as temporal lobe epilepsy.

Animals↗
PubMed2003

Maximizing children's physical activity: an evaluability assessment to plan a community-based, multi-strategy approach in an ethno-racially and socio-economically diverse city.

An evaluability assessment was conducted to plan a community-based, multi-strategy approach to physical activity promotion (MSAPAP) to maximize young children's physical activity in an ethno-racially and socio-economically diverse city. This assessment involved consultation with various stakeholders to develop a program logic model to diagrammatically describe the MSAPAP. First, published literature regarding physical activity was reviewed to describe interventions designed to increase children's physical activity and to identify factors that contributed to program effectiveness. Secondly, key informants from mainstream service organizations and smaller community-based agencies were interviewed to determine their views on how to increase physical activity among children and families. A workgroup developed a draft logic model based on the results of the literature review and community needs assessment results. Thirdly, stakeholders were consulted about the draft model. This consisted of 12 focus groups with members of school boards (two sessions), members of community organizations (three sessions), lay home visitors who provide support to mothers of young children in ethno-racially diverse communities (one session), and parents from six cultural groups (six sessions). The logic model was revised based on the findings from this consultation. The final logic model shows children aged 3-8 years as the main target group, and parents and various community members who influence children as intermediate target groups. The MSAPAP is depicted as six strategies, which are clusters of program activities that are conceptually similar: community engagement, community assessment, accessibility, promotion, education and skill development, and inclusive programming. The logic model shows the 'cause and effect' relationships among program activities, shorter-term outcome objectives (e.g. to reduce user fees for physical activity programs) and longer-term outcome objectives (e.g. to increase the proportion of children who are physically active). The extensive community involvement in planning the MSAPAP facilitated a subsequent plan to develop, implement and evaluate selected program activities in the MSAPAP.

Child↗