Project description:Transcriptomic analysis of rats with intracerebroventricular administration of 192Ig-saporin in the ventral and dorsal parts of the hippocampus
Project description:This experiment seeks to ascertain the transcriptional changes in the adult mouse hippocampus (CA1 subregion) that occur following viral knockdown of the histone variant H2A.Z. We are especially interested in understanding the role of this histone variant in memory formation and memory maintenance in the adult central nervous system.
Project description:Borna Disease Virus (BDV) is a neurotropic virus that persistently infects neurons in the central nervous system of various hosts, including rats. Although BDV is known to be an IFN sensitive virus, determination of the cellular mRNA transcript levels revealed the induction of IFN-stimulated genes in organotypic rat hippocampus slice cultures, raising the question how BDV evades this innate immune response. Using rat Mx protein as a specific marker for IFN-induced gene products, we could show that neurons lack detectable levels of Mx in these BDV infected cultures, whereas astrocytes and microglial cells were Mx positive. Neurons remained Mx negative after treatment of uninfected hippocampus cultures as well as primary dissociated neuronal cultures with high concentrations of IFN-α. This non-responsiveness correlated with a lack of a detectable nuclear translocation of pSTAT1 in rat neurons. Consistently, IFN treatment of BDV-infected rat neurons did not prevent the establishment of a viral persistence in the neuronal tissue. However, IFN treatment efficiently prevented vesicular stomatitis virus (VSV) replication, indicating that these cells can mount a weak innate immune response. In contrast, IFN treatment of mouse neurons resulted in the upregulation of Mx1 proteins and inhibition of BDV replication, indicating species-specific differences in the IFN response in neurons between mice and rats. Rat neurons may therefore represent the ideal cell type for BDV to evade the innate immune in the central nervous system.
Project description:Neurodegenerative brain disorders become more common in the aged. Most of these disorders are associated with or caused by selective death of certain neuronal subpopulations. The mechanisms underlying the differential vulnerability of certain neuronal populations are still largely unexplored and few neuroprotective treatments are available to date. Elucidation of these mechanisms may lead to a greater understanding of the pathogenesis and treatment of neurodegenerative diseases. Moreover, preconditioning by a short seizure confers neuroprotection following a subsequent prolonged seizure. Our goal is to identify pathways that confer vulnerability and resistance to neurotoxic conditions by comparing the basal and preconditioned gene expression profiles of three differentially vulnerable hippocampal neuron populations. Hippocampal CA1 and CA3 pyramidal neurons are highly susceptible to seizures and ischemia, whereas dentate gyrus granule cells are relatively resistant. A brief preconditioning seizure confers protection to the pyramidal cells. We will first determine gene expression profiles of untreated rat CA1 and CA3 pyramidal cells, and dentate granule cells, using laser capture microscopy to obtain region-specific neuronal mRNA. We will then determine the effect of a brief preconditioning seizure, which is neuroprotective in CA1 and CA3, on these expression profiles. We hypothesize that common molecular mechanisms exist in neurons that determine their susceptibility to seizure-induced injury. Intrinsic differences in gene expression exist between hippocampal glutamatergic CA1 and CA3 pyramidal neurons, on the one hand, and dentate granule cells on the other, which contribute to the greater susceptibility of pyramidal neurons to degeneration in experimental stroke and epilepsy. We specifically hypothesize that differences in basal energy metabolism genes may confer differential susceptibility to neurodegeneration produced by seizures and ischemia. Anesthetized animals will be sacrificed by decapitation, and frozen 10 micron sections will be lightly stained with cresyl violet to identify cell layers in the hippocampus. Approximately 1000 neurons from each of the three cell layers will be isolated by LCM. Poly-A RNA will be amplified using a modified Eberwine protocol. The quality of our aRNA will be evaluated by quantitative RT-PCR of GluR6 and KA2 mRNA levels before we send the samples to the Center for labeling and hybridization to Affymetrix rat 230A arrays. We will provide a one-round amplification cDNA product to the center for labeling and hybridization. This protocol is identical to a previously approved study by Jim Greene in our laboratory.
Project description:The hippocampus - one of the most studied brain regions – is a key target of the stress response and vulnerable to the detrimental effects of stress. Although its intrinsic organization is highly conserved throughout its long dorsal-ventral axis, the dorsal hippocampus is linked to spatial navigation and memory formation, whereas the ventral hippocampus is linked to emotional regulation. Here, we provide the first combined transcriptomic and proteomic profiling that reveals striking differences between dorsal and ventral hippocampus. Using various acute stress challenges we demonstrate that both regions display very distinct molecular responses, and that the ventral hippocampus is particularly responsive to the effects of stress. We demonstrate that separately analyzing dorsal and ventral hippocampus greatly increases the ability to detect region-specific stress effects, and we identify an epigenetic network, which is specifically sensitive to acute stress in the ventral hippocampus.
Project description:We applied Solexa sequencing technology to identify rat microRNA genes in dorsal root ganglia (DRGs) following sciatic nerve resection. Using Solexa sequencing, computational analysis and Q-PCR verification, 114 novel miRNAs in rats were discovered and identified, of which 52 novel miRNAs were first reported in rat DRGs and 62 novel miRNAs were produced at days 1, 4, 7 and 14 after sciatic nerve resection. These data provide an important resource relating to the role and regulation of miRNAs for future studies relating to peripheral nerve injury and regeneration.
Project description:The rodent hippocampus is a spatially organized neuronal network that supports the formation of spatial and episodic memories. We conducted bulk RNA sequencing and spatial transcriptomics experiments to measure gene expression changes in the dorsal hippocampus following the recall of active place avoidance (APA) memory. Through bulk RNA sequencing, we examined the gene expression changes following memory recall across the functionally distinct subregions of the dorsal hippocampus. We found that recall induced differentially expressed genes (DEGs) in the CA1 and CA3 hippocampal subregions were enriched with genes involved in synaptic transmission and synaptic plasticity, while DEGs in the dentate gyrus (DG) were enriched with genes involved in energy balance and ribosomal function. Through spatial transcriptomics, we examined gene expression changes following memory recall across an array of spots encompassing putative memory-associated neuronal ensembles marked by the expression of the IEGs Arc, Egr1, and c-Jun. Within samples from both trained and untrained mice, the subpopulations of spatial transcriptomic spots marked by these IEGs were transcriptomically and spatially distinct from one another. DEGs detected between Arc+ and Arc- spots exclusively in the trained mouse were enriched in several memory-related gene ontology terms, including “regulation of synaptic plasticity” and “memory.” Our results suggest that APA memory recall is supported by regionalized transcriptomic profiles separating the CA1 and CA3 from the DG, transcriptionally and spatially distinct IEG expressing spatial transcriptomic spots, and biological processes related to synaptic plasticity as a defining the difference between Arc+ and Arc- spatial transcriptomic spots.