FoxO6 regulates memory consolidation and synaptic function.
Ontology highlight
ABSTRACT: We used microarrays to assess gene expression differences in the hippocampus between FoxO6 mutant and wild-type siblings before (basal) or after novel object learning. The cohort of basal mice were housed individually for at least 3 days prior to tissue harvesting. The mice used to collect hippocampal samples after the object learning task were handled daily in the procedure room, prior to the object learning task. 24 hours before the object learning task, each mouse was individually habituated to the empty novel object arena for 10 min. On the days of the novel object learning task and the empty arena habituation, the mice were transferred to the procedure room and acclimatized for 60 min. For the novel object learning task, the mice were allowed to explore two identical and novel objects for 10 min in a 70 x 70 x 70 cm black plastic arena with a white PVC vinyl material on the base. After the object exploration, mice were transferred to an empty cage, and were euthanized after 60 min. The brains were dissected and incubated in ice-cold RNAlater (Ambion) for 24 hours at 4M-BM-:C. The brains were then rapidly frozen in O.C.T. Tissue-Tek (Sakura) at -80M-BM-:C. Coronal brain sections (300 M-BM-5m) were made using a microtome (Microm), the hippocampus was finely dissected and collected into M-bM-^@M-^XRNA lysis bufferM-bM-^@M-^Y (Ambion), and homogenized for 30 sec using a rotar-stat homogenizer. Total RNA was extracted using the RNAqueous column (Ambion) following the manufacturerM-bM-^@M-^Ys protocol.
Project description:The purpose of this study was to determine the effect of peripheral (IV) administration of AβPP antisense on hippocampal gene expression as well as on learning and memory as measured by T-maze in adult male mice aged 12 months. The AβPP antisense treatment reversed learning and memory deficits and altered the expression of 944 hippocampal genes, which are involved in a coordinated set of signaling pathways. Expression and pathway findings were verified at the protein and functional (phosphorylation) levels. Global differential profiling of hippocampal gene expression (12 month old adult mice: Control, SAMP8, SAMP8 + Random antisense, SAMP8 + AβPP antisense) was performed using Affymetrix GeneChip® Mouse Genome 430 2.0 Arrays. The AβPP antisense reversed the memory deficits and altered expression of 944 hippocampal genes. Pathway analysis showed significant gene expression changes in 9 pathways. These include the MAPK signaling pathway (P = 0.0078) and the phosphatidylinositol signaling pathway (P = 0.043), which we have previously shown to be altered in SAMP8 mice. The changes in these pathways contributed to significant changes in the Neurotropin (P = 0.0083) and Insulin Signaling (P = 0.015) pathways, which are known to be important in learning and memory. Changes in these pathways were accompanied by phosphorylation changes in the downstream target proteins p70S6K, GSK3β, ERK, and CREB. These changes in hippocampal gene expression and protein phosphorylation may suggest specific new targets for antisense therapy aimed at improving memory. One-way ANOVA (4 conditions, n=4). Variables were treatment (AβPP antisense, Random antisense, no treatment) and mouse strain (Control and SAMP8). This results in 4 groups: (All 12-month-old adult male mice) NT-Control, NT_SAMP8, Random_AS-SAMP8, and AβPP_AS-SAMP8. Each group had 4 biological replicates (4 mice). The 'Control' mice were a 50% backcross of the SAMP8 mice with CD-1 mice (50% SAMP8 mice). These mice were closely related to SAMP8 mice but exhibited no memory deficits at 4 or 12 months. The SAMP8 mice had memory deficits at 12 months but not at 4 months.
Project description:The purpose of this study was to determine whether there were differences in gene expression in the hippocampus, a part of the brain involved in memory consolidation, between male mice with age-related memory deficits (SAMP8 mice) and control mice with no age-related memory deficits. The senescence-accelerated mouse (SAMP8) strain exhibits decreased learning and memory and increased amyloid beta peptide (Aβ) accumulation at 12 months compared to 4 months. To detect differences in gene expression in SAMP8 mice, we used a Control mouse that was a 50% cross between SAMP8 and CD-1 mice and which showed no memory deficits (50% SAMP8 mouse). We then compared gene expression in the hippocampus of 4 month and 12 month old SAMP8 and Control mice using Affymetrix gene arrays. At 12 months, but not at 4 months, pathway analysis revealed significant differences in the Long Term Potentiation (LTP) (6 genes), Phosphatidylinositol Signaling (6 genes), and Endocytosis (10 genes) pathways. The changes in LTP included MAPK signaling (N-ras, CREB binding protein, protein phosphatase inhibitor 1) and Ca-dependent signaling (PI receptors 1 and 2 and phospholipase C). Changes in phosphatidylinositol signaling genes suggested altered signaling through PI3-kinase, and Western blotting revealed phosphorylation changes in AKT and 70S6K. Changes in the Endocytosis pathway involved genes related to clathrin-mediated endocytosis (dynamin and clathrin). Endocytosis is required for receptor recycling, is involved in Aβ metabolism, and is regulated by phosphatidylinositol signaling. In summary, these studies demonstrate altered genes expression in three SAMP8 hippocampal pathways associated with memory formation and consolidation. These pathways may provide new therapeutic targets in addition to targeting Aβ metabolism itself. Global differential profiling of hippocampal gene expression (4 month and 12 month old SAMP8 and Control mice) was performed using Affymetrix GeneChip® Mouse Genome 430 2.0 Arrays. At 12 months, but not at 4 months, pathway analysis revealed significant differences in the Long Term Potentiation (LTP) (6 genes), Phosphatidylinositol Signaling (6 genes), and Endocytosis (10 genes) pathways. The changes in LTP included MAPK signaling (N-ras, CREB binding protein, protein phosphatase inhibitor 1) and Ca-dependent signaling (PI receptors 1 and 2 and phospholipase C). Changes in phosphatidylinositol signaling genes suggested altered signaling through PI3-kinase, and Western blotting revealed phosphorylation changes in AKT and 70S6K. Changes in the Endocytosis pathway involved genes related to clathrin-mediated endocytosis (dynamin and clathrin). Endocytosis is required for receptor recycling, is involved in Aβ metabolism, and is regulated by phosphatidylinositol signaling. In summary, these studies demonstrate altered genes expression in three SAMP8 hippocampal pathways associated with memory formation and consolidation. These pathways may provide new therapeutic targets in addition to targeting Aβ metabolism itself. 2-way ANOVA (2 x 2 conditions, n=4). First variable was age (4 and 12 months) and second variable was mouse strain (Control and SAMP8). This results in 4 groups: Control-4 month, Control-12 month, SAMP8-4 month, and SAMP8-12 month. Each group had 4 biological replicates (4 mice). The ”Control” mice were a 50% backcross of the SAMP8 mice with CD-1 mice (50% SAMP8 mice). These mice were closely related to SAMP8 mice but exhibited no memory deficits at 4 or 12 months. The SAMP8 mice had memory deficits at 12 months but not at 4 months.
Project description:Aging is often associated with cognitive decline, but many elderly individuals maintain a high level of function throughout life. Here we studied outbred rats, which also exhibit individual differences across a spectrum of outcomes that includes both preserved and impaired spatial memory. Previous work in this model identified the CA3 subfield of the hippocampus as a region critically affected by age and integral to differing cognitive outcomes. Earlier microarray profiling revealed distinct gene expression profiles in the CA3 region, under basal conditions, for aged rats with intact memory and those with impairment. Because prominent age-related deficits within the CA3 occur during neural encoding of new information, here we used microarray analysis to gain a broad perspective of the aged CA3 transcriptome under activated conditions. Behaviorally induced CA3 expression profiles differentiated aged rats with intact memory from those with impaired memory. In the activated profile, we observed substantial numbers of genes (greater than 1000) exhibiting increased expression in aged unimpaired rats relative to aged impaired, including many involved in synaptic plasticity and memory mechanisms. This unimpaired aged profile also overlapped significantly with a learning induced gene profile previously acquired in young adults. Alongside the increased transcripts common to both young learning and aged rats with preserved memory, many transcripts behaviorally-activated in the current study had previously been identified as repressed in the aged unimpaired phenotype in basal expression. A further distinct feature of the activated profile of aged rats with intact memory is the increased expression of an ensemble of genes involved in inhibitory synapse function, which could control the phenotype of neural hyperexcitability found in the CA3 region of aged impaired rats. These data support the conclusion that aged subjects with preserved memory recruit adaptive mechanisms to retain tight control over excitability under both basal and activated conditions. RNA profiles from cognitively unimpaired and impaired aged rats were compared under 2 conditions: spatial learning task and a non-spatial learning task.
Project description:We performed single-cell RNA-seq of full, microdissected and dissociated mouse amygdala, 2h, 8h or 24h after tone-cued fear conditioning (CFC), and 2h after recall (exposure to CS only, 24h post-CFC), and naive homecage controls.
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.
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.
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.
Project description:Increasing evidence suggests microRNAs (miRNAs) control levels of mRNA expression during development of the nervous system and during sensory elicited remodelling of the brain. We used an associative olfactory learning paradigm (proboscis extension response) in the honeybee Apis mellifera to detect gene expression changes in the brain. Transcriptome analysis of bees trained to associate an odor with a reward and control bees exposed to air without reward, helped us abstract mRNA-miRNA interactions for empirical testing. Functional studies, feeding cholesterol-conjugated antisense RNA to bees resulted in the inhibition of miR-210 and of miR-932 that is embedded within the neuroligin 2 (Nlg2) gene involved in synapse development. Loss of miR-932 prevents long-term memory formation but not learning. We validated 3M-bM-^@M-^YUTR target site interactions of miR-932 and show miR-932 dysregulates actin, a key cytoskeletal molecule involved in neuronal development and activity-dependent plasticity of the brain. The analysis used Air group (no odor learning) as control sample for comparison to two groups of odor-conditioned bees: linalool and floral mix.
Project description:We used microarrays to assess gene expression differences in the hippocampus between FoxO6 mutant and wild-type siblings before (basal) or after novel object learning.