DISC1 and reelin interact to alter cognition, inhibition, and neurogenesis in a novel mouse model of schizophrenia.

The etiology of schizophrenia (SCZ) is multifactorial, and depending on a host of genetic and environmental factors. Two putative SCZ susceptibility genes, Disrupted-in-Schizophrenia-1 (DISC1) and reelin (RELN), interact at a molecular level, suggesting that combined disruption of both may lead to an intensified SCZ phenotype. To examine this gene-gene interaction, we produced a double mutant mouse line.

Spermidine/spermine-N-acetyltransferase ablation impacts tauopathy-induced polyamine stress response.

Background: Tau stabilizes microtubules; however, in Alzheimer's disease (AD) and tauopathies, tau becomes hyperphosphorylated, aggregates, and results in neuronal death. Our group recently uncovered a unique interaction between polyamine metabolism and tau fate. Polyamines exert an array of physiological effects that support neuronal function and cognitive processing.

Reelin Proteolysis Affects Signaling Related to Normal Synapse Function and Neurodegeneration.

Reelin is a neurodevelopmental protein important in adult synaptic plasticity and learning and memory. Recent evidence points to the importance for Reelin proteolysis in normal signaling and in cognitive function. Support for the dysfunction of Reelin proteolysis in neurodegeneration and cognitive dysfunction comes from postmortem analysis of Alzheimer's diseases (AD) tissues including cerebral spinal fluid (CSF), showing that levels of Reelin fragments are altered in AD compared to control.

Reelin supplementation recovers synaptic plasticity and cognitive deficits in a mouse model for Angelman syndrome.

The Reelin signaling pathway is implicated in processes controlling synaptic plasticity and hippocampus-dependent learning and memory. A single direct in vivo application of Reelin enhances long-term potentiation, increases dendritic spine density and improves associative and spatial learning and memory. Angelman syndrome (AS) is a neurological disorder that presents with an overall defect in synaptic function, including decreased long-term potentiation, reduced dendritic spine density, and deficits in learning and memory, making it an attractive model in which to examine the ability of Reelin to recover synaptic function and cognitive deficits.

Imipramine protects against the deleterious effects of chronic corticosterone on depression-like behavior, hippocampal reelin expression, and neuronal maturation.

We have hypothesized that a downregulation of reelin and deficient maturation of adult-born hippocampal neurons are important factors in the pathogenesis of depression. This hypothesis is based on previous work showing that depression-like behavior in rats treated with protracted corticosterone develops in concert with decreased dendritic complexity in newborn hippocampal granule neurons and decreased reelin expression in the proliferative subgranular zone of the dentate gyrus. In addition, heterozygous reeler mice with approximately 50% of normal brain levels of reelin are more vulnerable to the depressogenic effects of corticosterone than wild-type mice.

The progressive development of depression-like behavior in corticosterone-treated rats is paralleled by slowed granule cell maturation and decreased reelin expression in the adult dentate gyrus.

We have hypothesized that the extracellular matrix protein reelin is involved in the pathogenesis of major depression. This hypothesis is based on previous work in which we showed that repeated exposure to the stress hormone corticosterone, which increases depression-like behavior in rodents, also decreases the number of reelin+ cells in specific regions of the hippocampus and decreases hippocampal neurogenesis. In addition, we have found that heterozygous reeler mice, which express approximately 50% of normal brain levels of reelin, are more susceptible to the depressogenic effects of corticosterone than their wild-type counterparts.

The coexpression of reelin and neuronal nitric oxide synthase in a subpopulation of dentate gyrus neurons is downregulated in heterozygous reeler mice.

Reelin is an extracellular matrix protein expressed in several interneuron subtypes in the hippocampus and dentate gyrus. Neuronal nitric oxide synthase (nNOS) is also expressed by interneurons in these areas. We investigated whether reelin and nNOS are co-localized in the same population of hippocampal interneurons, and whether this colocalization is altered in the heterozygous reeler mouse.

Reelin as a putative vulnerability factor for depression: examining the depressogenic effects of repeated corticosterone in heterozygous reeler mice.

We examined a potential two-hit murine animal model of depression by assessing whether a genetic deficit in reelin increases vulnerability to the depressogenic effects of the stress hormone corticosterone. Stress is an identified risk factor for the onset of depressive symptoms, but depression also has a significant genetic component, suggesting that environmental factors and genetic background likely interact in the etiology of depression. Previous results have revealed that reelin levels are decreased in post-mortem hippocampal tissue from patients with schizophrenia, bipolar disorder and depression, and also in an animal model of depression.

Repeated exposure to corticosterone, but not restraint, decreases the number of reelin-positive cells in the adult rat hippocampus.

Stress is an important risk factor for the emergence of depression, but little is known about the neurobiological mechanisms by which stress might promote depressive symptomatology. Much of the research on this topic has focused on stress-induced changes in hippocampal plasticity, specifically the idea that decreased hippocampal plasticity could be a precipitating factor for depression. Interestingly, recent evidence has described a regulatory role for the extracellular matrix protein reelin in important aspects of neural plasticity within the hippocampus and dentate gyrus.