Project description:Memory allocation refers to the process by which neurons are recruited into the encoding ensemble to store learned information. This recruitment is regulated by neuronal selection based on differences in intrinsic excitability (IE) and the expression of the transcription factor CREB. However, whether other forms of plasticity influence memory allocation remains unknown. Here, we found that chromatin compaction and histone acetylation in the mouse lateral amygdala display a high degree of heterogeneity, a prerequisite for neuronal selection. Consequently, when we increased histone acetylation by overexpressing histone acetyl transferases (HATs), neurons with elevated histone acetylation were preferentially recruited into the encoding ensemble and memory retention was enhanced, while optogenetic silencing of the epigenetically altered neurons prevented memory expression. Mechanistically, using patch-clamp recordings and single-nucleus multi-ome sequencing, we observed that HAT overexpression increased IE and epitranscriptomic changes favoring synaptic plasticity. Lastly, by merging FRET-based epigenetic beacons with calcium indicators to simultaneously record histone acetylation and neuronal dynamics in real time, we found that epigenetic heterogeneity underlies IE in cell-autonomous manner. These results identify chromatin plasticity as a key factor catalyzing memory allocation.
Project description:A selection experiment has been set that selects females Mercurialis annua for increased allocation in male functions by depriving selected populations of all males. This resulted in a drastic phenotypic shift in sex allocation in females of the selected lines. The present RNA sequencing of control and selected lines after four generations of selection permits us to track the expression levels of previously identified male- and female-biased genes in females of the selected lines.
Project description:Turnover and exchange of nucleosomal histones and their variants, a process long believed to be static in post-replicative cells, remains largely unexplored in brain. Here, we describe a novel mechanistic role for HIRA (histone cell cycle regulator) and proteasomal degradation associated histone dynamics in the regulation of activity-dependent transcription, synaptic connectivity and behavior. We uncover a dramatic developmental profile of nucleosome occupancy across the lifespan of both rodents and humans, with the histone variant H3.3 accumulating to near saturating levels throughout the neuronal genome by mid-adolescence. Despite such accumulation, H3.3 containing nucleosomes remain highly dynamic–in a modification independent manner–to control neuronal- and glial- specific gene expression patterns throughout life. Manipulating H3.3 dynamics in both embryonic and adult neurons confirmed its essential role in neuronal plasticity and cognition. Our findings establish histone turnover as a critical, and previously undocumented, regulator of cell-type specific transcription and plasticity in mammalian brain. All ChIP-seq samples were generated to test the impact of neuronal activity/adult physiological plasticity on histone turnover in the central nervous system. This was tested in cultured neurons and astrocytes, FACS purified neurons or FACS purified Glia.
Project description:Turnover and exchange of nucleosomal histones and their variants, a process long believed to be static in post-replicative cells, remains largely unexplored in brain. Here, we describe a novel mechanistic role for HIRA (histone cell cycle regulator) and proteasomal degradation associated histone dynamics in the regulation of activity-dependent transcription, synaptic connectivity and behavior. We uncover a dramatic developmental profile of nucleosome occupancy across the lifespan of both rodents and humans, with the histone variant H3.3 accumulating to near saturating levels throughout the neuronal genome by mid-adolescence. Despite such accumulation, H3.3 containing nucleosomes remain highly dynamic–in a modification independent manner–to control neuronal- and glial- specific gene expression patterns throughout life. Manipulating H3.3 dynamics in both embryonic and adult neurons confirmed its essential role in neuronal plasticity and cognition. Our findings establish histone turnover as a critical, and previously undocumented, regulator of cell-type specific transcription and plasticity in mammalian brain. All RNA-seq samples were generated to test the impact of neuronal activity/adult physiological plasticity on histone turnover turnover mediated alterations in mRNA expression in the central nervous system. This was tested in cultured neurons and astrocytes, and embryonic/adult brain tissues
Project description:The transcription factor Mef2 regulates activity-dependent neuronal plasticity and morphology in mammals, and clock neurons are reported to experience activity-dependent circadian remodeling in Drosophila. We show here that Mef2 is required for this daily fasciculation-defasciculation cycle. Moreover, the master circadian transcription complex CLK/CYC directly regulates Mef2 transcription. ChIP-Chip analysis identified numerous Mef2 target genes implicated in neuronal plasticity, including the cell-adhesion gene Fas2. Genetic epistasis experiments support this transcriptional regulatory hierarchy, CLK/CYC->Mef2-> Fas2, indicate that it influences the circadian fasciculation cycle within pacemaker neurons and suggest that this cycle also contributes to circadian behavior. Mef2 therefore transmits clock information to machinery involved in neuronal remodeling, which contributes to locomotor activity rhythms. Mef2 ChIP-chip samples collected at 6 timepoints, input and IP samples
Project description:Brain organoids are promising tools for disease modelling and drug development. For proper neuronal network formation excitatory and inhibitory neurons as well as glia need to co-develop. Here we report the directed differentiation and self-organization of induced pluripotent stem cells in a collagen hydrogel towards a highly interconnected neuronal network in a macroscale tissue format. Bioengineered Neuronal Organoids (BENOs) comprise interconnected excitatory and inhibitory neurons as well as supportive astrocytes and oligodendrocytes. Giant depolarizing potential (GDP)-like events observed within 20-40 days of BENO culture mimic early network activity of the fetal brain. The switch from excitatory to inhibitory GABA activity, and reduced GDPs at >40 day BENO cultures indicate progressive neuronal network maturation. BENOs demonstrate expedited complex network burst development after two months of culture and provide the first evidence for long-term potentiation and plasticity in brain organoids. BENOs exhibit structural and functional properties similar to the fetal brain and thus may be explored as a model to study the development of neuronal plasticity.
Project description:We report gene expression patterns for the flatworm Macrostomum lignano in four different social envirionments expected to influence allocation to the male and female sex functions
Project description:Surface proteins are of fundamental importance for formation of synaptic connections and activity-dependent plasticity. Here, we used a spatiotemporally resolved cell-surface proteotype analysis to characterize the neuronal surface-exposed proteome, or surfaceome, during neuronal development and synapse formation in primary neuronal cultures. We established a map of the neuronal surfaceome, which includes about 1,000 surface proteins, and analyzed the dynamic remodeling of the quantitative surfaceome during development. We identified time-resolved surface-abundance profile clusters that correspond to distinct stages of neuronal development. We discovered that surface abundance changes can correlate with or be uncoupled from the total cellular abundance. Finally, we observed system-wide surfaceome modulation in response to homeostatic synaptic scaling and exocytosis of diverse cargo during long-term potentiation.