Hippocampal Subregion Transcriptomic Profiles Associated with Age-Related Changes in Spatial Pattern Separation
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PROVIDER: PRJNA589647 | ENA |
REPOSITORIES: ENA
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Project description:Previous studies of age-related transcriptional changes indicate that cognitive impairments are associated with differentially expressed genes DEGs linked to defined neural systems; however, studies that examine multiple regions of the hippocampus fail to find major links between behavior and transcription in the dentate gyrus DG. The DG is implicated in pattern separation PS and exhibits multiple age-related changes that may affect PS performance. We hypothesize that an age-related decline in PS performance is associated with distinct changes in transcriptional profile, most strongly within the DG compared to other hippocampal subregions. We used a water maze beacon discrimination task to characterize PS in young 5 mo and middle-age 12 mo male F344 rats, followed by a spatial reference memory test. Middle-age rats showed consistent deficits in discriminating two identical beacons compared to young. Reference memory was not different between these two age groups. Interestingly, with increasing spatial overlap between the cues, older animals appeared to compensate for impaired PS performance though greater reliance on spatial reference memory. mRNA sequencing of hippocampal subregions DG, CA1, and CA3 indicated that the DG of middle-age rats expressed more genes correlated with PS performance. In contrast, reliance on a spatial reference memory was associated with differential expression of genes in regions CA1 and CA3. These results indicate that the beacon task is sensitive to PS impairment as early as middle-age, and distinct gene profiles are observed in neural circuits that underlie different strategies used to solve the task.
2020-05-22 | GSE140420 | GEO
Project description:Seizure-induced LIN28A disrupts pattern separation via aberrant hippocampal neurogenesis
| PRJNA1033558 | ENA
Project description:A theoretical framework for the function of the medial temporal lobe system in memory defines differential contributions of the hippocampal subregions with regard to pattern recognition retrieval processes and encoding of new information. To investigate molecular programs of relevance, we designed a spatial learning protocol to engage a pattern separation function to encode new information. After background training, two groups of animals experienced the same new training in a novel environment, however only one group was provided spatial information and demonstrated spatial memory in a retention test. Global transcriptional analysis of the microdissected subregions of the hippocampus exposed a CA3 pattern that was sufficient to clearly segregate spatial learning animals from control. Individual gene and functional group analysis anchored these results to previous work in neural plasticity. From a multitude of expression changes, increases in camk2a, rasgrp1 and nlgn1 were confirmed by in situ hybridization. Furthermore, siRNA inhibition of nlgn1 within the CA3 subregion impaired spatial memory performance, pointing to mechanisms of synaptic remodeling as a basis for rapid encoding of new information in long-term memory. Experiment Overall Design: RNA samples from animals subjected to a spatial learning paradigm were compared to controls using Affymetirx RAE230a chips. An N of 7 was used in each of the two experimental conditions.
2008-06-18 | E-GEOD-11475 | biostudies-arrayexpress
Project description:Post-learning sleep plays an important role in hippocampal memory processing, including contextual fear memory (CFM) consolidation. Here, we used targeted recombination in activated populations (TRAP) to label context-encoding engram neurons in the hippocampal dentate gyrus (DG) and assessed reactivation of these neurons during post-learning sleep. We find that post-learning sleep deprivation (SD), which impairs CFM consolidation, selectively disrupts reactivation in inferior blade DG engram neurons. This change was linked to more general suppression of neuronal activity markers in the inferior, but not superior, DG blade by SD. To further characterize how learning and subsequent sleep or SD affect these (and other) hippocampal subregions, we used subregion-specific spatial profiling of transcripts and proteins. We found that transcriptomic responses to sleep loss differed greatly between hippocampal regions CA1, CA3, and DG inferior blade, superior blade, and hilus. Critically, learning-driven transcriptomic changes, measured 6 h following contextual fear learning, were limited to the two DG blades, differed dramatically between the blades, and were absent from all other regions. Similarly, protein abundance in these hippocampal subregions were differentially impacted by sleep vs. SD and by prior learning, with the majority of alterations to protein expression restricted to DG. Together, these data suggest that the DG plays an essential role in the consolidation of hippocampal memories, and that the effects of sleep and sleep loss on the brain are highly subregion-specific, even within the DG itself.
2024-03-01 | GSE229080 | GEO
Project description:Post-learning sleep plays an important role in hippocampal memory processing, including contextual fear memory (CFM) consolidation. Here, we used targeted recombination in activated populations (TRAP) to label context-encoding engram neurons in the hippocampal dentate gyrus (DG) and assessed reactivation of these neurons during post-learning sleep. We find that post-learning sleep deprivation (SD), which impairs CFM consolidation, selectively disrupts reactivation in inferior blade DG engram neurons. This change was linked to more general suppression of neuronal activity markers in the inferior, but not superior, DG blade by SD. To further characterize how learning and subsequent sleep or SD affect these (and other) hippocampal subregions, we used subregion-specific spatial profiling of transcripts and proteins. We found that transcriptomic responses to sleep loss differed greatly between hippocampal regions CA1, CA3, and DG inferior blade, superior blade, and hilus. Critically, learning-driven transcriptomic changes, measured 6 h following contextual fear learning, were limited to the two DG blades, differed dramatically between the blades, and were absent from all other regions. Similarly, protein abundance in these hippocampal subregions were differentially impacted by sleep vs. SD and by prior learning, with the majority of alterations to protein expression restricted to DG. Together, these data suggest that the DG plays an essential role in the consolidation of hippocampal memories, and that the effects of sleep and sleep loss on the brain are highly subregion-specific, even within the DG itself.
2024-03-01 | GSE229081 | GEO
Project description:A theoretical framework for the function of the medial temporal lobe system in memory defines differential contributions of the hippocampal subregions with regard to pattern recognition retrieval processes and encoding of new information. To investigate molecular programs of relevance, we designed a spatial learning protocol to engage a pattern separation function to encode new information. After background training, two groups of animals experienced the same new training in a novel environment, however only one group was provided spatial information and demonstrated spatial memory in a retention test. Global transcriptional analysis of the microdissected subregions of the hippocampus exposed a CA3 pattern that was sufficient to clearly segregate spatial learning animals from control. Individual gene and functional group analysis anchored these results to previous work in neural plasticity. From a multitude of expression changes, increases in camk2a, rasgrp1 and nlgn1 were confirmed by in situ hybridization. Furthermore, siRNA inhibition of nlgn1 within the CA3 subregion impaired spatial memory performance, pointing to mechanisms of synaptic remodeling as a basis for rapid encoding of new information in long-term memory. Experiment Overall Design: RNA samples from animals subjected to a spatial learning paradigm were compared to controls using Affymetirx RAE230a chips. An N of 6 was used in each of the two experimental conditions.
2008-06-18 | E-GEOD-11474 | biostudies-arrayexpress
Project description:Prolonged seizures can disrupt stem cell behavior in the adult hippocampus, an important brain structure for spatial memory. Here, using a mouse model of pilocarpine-induced status epilepticus (SE), we characterized spatiotemporal expression of Lin28a mRNA and proteins after SE. Unlike Lin28a transcripts, induction of LIN28A protein after SE was detected mainly in the subgranular zone, where immunoreactivity was found in progenitors, neuroblasts, and immature and mature granule neurons. To investigate roles of LIN28A in epilepsy, we generated Nestin-Cre::Lin28aloxP/loxP (cKO) and Nestin-Cre::Lin28a+/+ (WT) mice to block LIN28A upregulation in all neuronal lineages after acute seizure. Adult-generated neuron- and hippocampus-associated cognitive impairments were absent in epileptic LIN28A cKO mice as evaluated by pattern separation and contextual fear conditioning tests, respectively, while sham-manipulated WT and cKO animals showed comparable memory function. Moreover, numbers of hilar PROX1-expressing ectopic granule cells (EGCs), together with PROX1/NEUN+ mature EGCs, were significantly reduced in epileptic cKO mice. Transcriptomic analysis and immunohistochemical validation at 3 d post-pilocarpine provided potential LIN28A downstream targets such as serotonin receptor 4. Collectively, our findings indicate that LIN28A is a novel target for regulation of newborn neuron-associated memory dysfunction in epilepsy by modulating seizure-induced aberrant neurogenesis.
2024-01-01 | GSE246519 | GEO
Project description:Background: Traumatic brain injury (TBI) often results in diverse molecular responses, challenging traditional proteomic studies that measure average changes at tissue levels and fail to capture the complexity and heterogeneity of the affected tissues. Spatial proteomics offers a solution by providing insights into sub-region-specific alterations within tissues. This study focuses on the hippocampal sub-regions, analyzing proteomic expression profiles in mice at the acute (1 day) and subacute (7 days) phases of post-TBI to understand subregion-specific vulnerabilities and long-term consequences. Methods: Three mice brains were collected from each group including Sham, 1-day post-TBI and 7-day post-TBI. Hippocampal subregions were extracted using Laser Microdissection (LMD); and subsequently analyzed by label-free quantitative proteomics. Results: The spatial analysis reveals region-specific protein abundance changes, highlighting the elevation of FN1, LGALS3BP, HP, and MUG-1 in the stratum moleculare (SM), suggesting potential immune cell enrichment post-TBI. Notably, established markers of chronic traumatic encephalopathy, IGHM and B2M, exhibit specific upregulation in the dentate gyrus bottom (DG2) independent of direct mechanical injury. Metabolic pathway analysis identifies disturbances in glucose and lipid metabolism, coupled with activated cholesterol synthesis pathways enriched in SM at 7-Day post-TBI and subsequently in deeper DG1 and DG2 suggesting a role in neurogenesis and onset of recovery. Coordinated activation of neuroglia and microtubule dynamics in DG2 suggest recovery mechanisms in less affected regions. Cluster analysis revealed spatial variations post-TBI, indicative of dysregulated neuronal plasticity and neurogenesis and further predisposition to neurological disorders. TBI-induced protein upregulation (MUG-1, PZP, GFAP, TJP, STAT-1 and CD44) across hippocampal sub-regions indicates shared molecular responses and links to neurological disorders. Spatial variations were demonstrated by proteins dysregulated in both or either of the time-points exclusively in each subregion (ELAVL2, CLIC1 in PL, CD44 and MUG-1 in SM, and SHOC2, LGALS3 in DG). Conclusions: Utilizing advanced spatial proteomics techniques, the study unveils the dynamic molecular responses in distinct hippocampal subregions post-TBI. It uncovers region-specific vulnerabilities and dysregulated neuronal processes, and potential recovery-related pathways that contribute to our understanding of TBI’s neurological consequences and provides valuable insights for biomarker discovery and therapeutic targets.
2024-06-23 | PXD051093 | Pride
Project description:A theoretical framework for the function of the medial temporal lobe system in memory defines differential contributions of the hippocampal subregions with regard to pattern recognition retrieval processes and encoding of new information. To investigate molecular programs of relevance, we designed a spatial learning protocol to engage a pattern separation function to encode new information. After background training, two groups of animals experienced the same new training in a novel environment, however only one group was provided spatial information and demonstrated spatial memory in a retention test. Global transcriptional analysis of the microdissected subregions of the hippocampus exposed a CA3 pattern that was sufficient to clearly segregate spatial learning animals from control. Individual gene and functional group analysis anchored these results to previous work in neural plasticity. From a multitude of expression changes, increases in camk2a, rasgrp1 and nlgn1 were confirmed by in situ hybridization. Furthermore, siRNA inhibition of nlgn1 within the CA3 subregion impaired spatial memory performance, pointing to mechanisms of synaptic remodeling as a basis for rapid encoding of new information in long-term memory. Experiment Overall Design: RNA samples from animals subjected to a spatial learning paradigm were compared to controls using Affymetirx RAE230a chips. An N of 7 was used in each of the two experimental conditions.
2008-06-18 | E-GEOD-11473 | biostudies-arrayexpress
Project description:Individuals with Down syndrome (DS) exhibit neurological deficits throughout the lifespan culminating in Alzheimer’s disease (AD) pathology and cognitive impairment during early mid-life. At the cellular level, dysregulation in neuronal gene expression has been shown in the human brain and mouse models of DS. However, RNA- sequencing (RNA-Seq) analysis of genomic neuronal expression in the hippocampus have been limited, without separation of neuronal populations based on circuitry inputs. We postulate spatially characterized hippocampal excitatory neurons will present with unique gene expression patterns due in part to unique circuitry inputs in the DS mouse model. Here, we combined laser capture microdissection (LCM) to isolate individual neuron populations with low input RNA-seq analysis to determine gene expression analysis of three excitatory neuron populations from the rostral hippocampus. We utilized the Ts65Dn mouse model of DS at the start of degeneration (6MO) to query gene expression profiles of CA1 and CA3 pyramidal neurons, along with dentate gyrus (DG) granule cells. The hippocampal structure is critical for learning and memory, with significant impairments of both behavior and synaptic activity in the DS mouse model which undergo degeneration during aging. Each population of excitatory hippocampal neurons exhibited unique gene expression alterations in the DS mice. Bioinformatic queries revealed unique vulnerabilities and mechanistic differences which coincide with onset of degeneration in the Ts65Dn model of DS/AD. These unique vulnerabilities may underlie the degenerative phenotype in DS, suggesting precision medicine targeting individual populations of neurons may be required for therapeutic advancement. We further analyzed maternal choline supplementation in each neuronal population, treating the dams during gestation through weaning with choline normal diet (1.1g/kc choline chloride) or choline suppmentation (5.0g/kg choline chloride) in the normal (AIN-76A) mouse chow from Dyets. At weaning (postnatal day 21), pups were aged on a choline normal diet until 6 months old.
2025-03-19 | GSE283699 | GEO