Project description:FTY720/Fingolimod, an FDA-approved drug for treatment of multiple sclerosis, has beneficial effects in the CNS that are not yet well understood, independent of its effects on immune cell trafficking. Here we show that FTY720 enters the nucleus where it is phosphorylated by sphingosine kinase 2 (SphK2) and nuclear FTY720-P that accumulates there, binds and inhibits class I histone deacetylases (HDACs) enhancing specific histone acetylations. FTY720 is also phosphorylated in mice and accumulates in various brain regions, including hippocampus, inhibits HDACs and enhances histone acetylation and gene expression programs associated with memory and learning leading to improvement of memory impairment independently of its immunosuppressive actions. Our data suggest that sphingosine-1-phosphate and SphK2 play specific roles in memory functions and that FTY720 may be a useful adjuvant therapy to facilitate extinction of aversive memories. Microarrays were used to survey the effect of FTY720 treatment during contextual fear conditioning on hippocampal gene expression. Total RNA was isolated from individual hippocampi of SCID mice 1 hour following fear consolidation testing after the third day of FTY720 or saline treatment. Eight arrays were run in total: 4 FTY720-treated mice and 4 saline-treated control mice.
Project description:The mechanisms underlying age-associated memory impairment are not well understood. We have shown that the onset of memory disturbances in the aging brain is associated with altered hippocampal chromatin plasticity. During learning, aged mice display a specific deregulation of histone H4 lysine 12 (H4K12) acetylation. To analyze if deregulated H4K12 acetylation impacts on learning-induced gene-expression required for memory consolidation we performed a high-density oligonucleotide microarray to compare the entire hippocampal gene-expression profile of 3 and 16-month-old mice during memory consolidation. In order to identify genes differentially regulated between 3- and 16-month old mice upon fear conditioning we subjected 3- and 16-month old mice to fear conditioning (4 mice each group, total 8 mice) . Mice of the same age that were handled but not subjected to any of the employed behavior paradigms served as control (4 mice 3-month old and 4 mice 16-month old, total 8 mice). During fear conditioning mice are subjected to a novel context followed by a mild electric foot-shock (context-shock exposure). In order to identify genes that are differentially regulated upon fear conditioning and are specific to associative learning we also tested the hippocampal gene-expression profile of 3-month old mice subjected to the same context-exposure that is not followed by a foot-shock (Context-exposure) (4 mice) or receive an immediate foot shock once they are placed in the context and only afterwards are allowed to explore the context (shock-context exposure) (4 mice). In order to identify genes that are regulated upon fear conditioning and are specific to associative learning we compared the hippocampal gene-expression profile of mice subjected to fear conditioning (context-shock), context or shock-context exposure regarding to their age-matched control mice (3 month old) mentioned above (control). Hippocampi from each mice were tested resulting to 24 samples which were separately hybridized (OneColor Array Design).
Project description:Quantitative proteomic analysis was used to identify the proteins associated with a formation of fear memory in mice. The proteins from the hippocampal region were isolated from three groups of trained aminals representing aquisition, consolidation and retrieval of a contextual fear conditioning. The samples were digested by trypsin, analyzed by LC-MSMS followed by protein identification and label-free quantitation using MaxQuant 1.3.0.5. Each group consisted of three individuals and each sample was processed in two technical replicates.
Project description:FTY720/Fingolimod, an FDA-approved drug for treatment of multiple sclerosis, has beneficial effects in the CNS that are not yet well understood, independent of its effects on immune cell trafficking. Here we show that FTY720 enters the nucleus where it is phosphorylated by sphingosine kinase 2 (SphK2) and nuclear FTY720-P that accumulates there, binds and inhibits class I histone deacetylases (HDACs) enhancing specific histone acetylations. FTY720 is also phosphorylated in mice and accumulates in various brain regions, including hippocampus, inhibits HDACs and enhances histone acetylation and gene expression programs associated with memory and learning leading to improvement of memory impairment independently of its immunosuppressive actions. Our data suggest that sphingosine-1-phosphate and SphK2 play specific roles in memory functions and that FTY720 may be a useful adjuvant therapy to facilitate extinction of aversive memories. Microarrays were used to survey the effect of FTY720 treatment during contextual fear conditioning on hippocampal gene expression.
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.
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.
Project description:Aim: We investigated the role of GR in Auditory Fear Conditioning memory consolidation by application of a pharmacological filter using selective glucocorticoid receptor modulators. Methods: Adult male mice were exposed to Auditory Fear Conditioning training and subsequently injected with 3.0 mg/kg corticosterone, 20 mg/kg CORT108297, 80 mg/kg CORT118335, 40 mg/kg RU486 or vehicle. Dorsal hippocampi were dissected 3 hours after injection and snap-frozen. Total RNA was isolated and send for 100bp paired-end sequencing by BGI.
Project description:Hippocampal tissues from 3xTg-AD mice treated with a CK1δ/ε inhibitor or vehicle, and non-transgenic mice treated with vehicle, were harvested and processed for proteomic analysis using label-free quantification.
Project description:Histone acetylation is a key component in the consolidation of long-term fear memories, which are models for highly resilient and durable memory. Histone acetylation is fueled by acetyl-CoA and recently, nuclear-localized metabolic enzymes that produce this metabolite have emerged as direct and local regulators of histone acetylation. In particular, Acetyl-coA synthetase 2 (ACSS2) mediates histone acetylation in the mouse hippocampus. However, whether ACSS2 regulates long-term fear memory remains to be determined. Here, we show that Acss2 knockout is well-tolerated in mice, yet the Acss2 null mouse exhibits reduced acquisition of long-term fear memory. Loss of Acss2 leads to reductions in both histone acetylation and expression of critical learning and memory-related genes in the dorsal hippocampus, specifically following fear conditioning. Further, systemic administration of blood-brain-barrier (BBB)-permeable Acss2 inhibitors during the consolidation window reduces fear memory formation in mice and rats, and reduces anxiety in a predator-scent-stress (PSS) paradigm. Our findings suggest that nuclear acetyl-CoA metabolism via ACSS2 plays a critical, previously unappreciated role in the formation of fear memories.