DNA G-Quadruplex Is a Transcriptional Control Device That Regulates Memory.

The conformational state of DNA fine-tunes the transcriptional rate and abundance of RNA. Here, we report that G-quadruplex DNA (G4-DNA) accumulates in neurons, in an experience-dependent manner, and that this is required for the transient silencing and activation of genes that are critically involved in learning and memory in male C57/BL6 mice. In addition, site-specific resolution of G4-DNA by dCas9-mediated deposition of the helicase DHX36 impairs fear extinction memory.

Fear extinction is regulated by the activity of long noncoding RNAs at the synapse.

Long noncoding RNAs (lncRNAs) represent a multidimensional class of regulatory molecules that are involved in many aspects of brain function. Emerging evidence indicates that lncRNAs are localized to the synapse; however, a direct role for their activity in this subcellular compartment in memory formation has yet to be demonstrated. Using lncRNA capture-seq, we identified a specific set of lncRNAs that accumulate in the synaptic compartment within the infralimbic prefrontal cortex of adult male C57/Bl6 mice.

Synapse-Enriched mA-Modified Malat1 Interacts with the Novel mA Reader, DPYSL2, and Is Required for Fear-Extinction Memory.

The RNA modification N-methyladenosine (mA) regulates the interaction between RNA and various RNA binding proteins within the nucleus and other subcellular compartments and has recently been shown to be involved in experience-dependent plasticity, learning, and memory. Using mA RNA-sequencing, we have discovered a distinct population of learning-related mA- modified RNAs at the synapse, which includes the long noncoding RNA metastasis-associated lung adenocarcinoma transcript 1 (). RNA immunoprecipitation and mass spectrometry revealed 12 new synapse-specific learning-induced mA readers in the mPFC of male C57/BL6 mice, with mA-modified binding to a subset of these, including CYFIP2 and DPYSL2.

Localised Cdr1as activity is required for fear extinction memory.

Circular RNAs (circRNAs) comprise a novel class of regulatory RNAs that are abundant in the brain, particularly within synapses. They are highly stable, dynamically regulated, and display a range of functions, including serving as decoys for microRNAs and proteins and, in some cases, circRNAs also undergo translation. Early work in animal models revealed an association between circRNAs and neurodegenerative and neuropsychiatric disorders; however, little is known about the link between circRNA function and memory.

ADRAM is an experience-dependent long noncoding RNA that drives fear extinction through a direct interaction with the chaperone protein 14-3-3.

Here, we used RNA capture-seq to identify a large population of lncRNAs that are expressed in the infralimbic prefrontal cortex of adult male mice in response to fear-related learning. Combining these data with cell-type-specific ATAC-seq on neurons that had been selectively activated by fear extinction learning, we find inducible 434 lncRNAs that are derived from enhancer regions in the vicinity of protein-coding genes. In particular, we discover an experience-induced lncRNA we call ADRAM (activity-dependent lncRNA associated with memory) that acts as both a scaffold and a combinatorial guide to recruit the brain-enriched chaperone protein 14-3-3 to the promoter of the memory-associated immediate-early gene Nr4a2 and is required fear extinction memory.

RNA N-Methyladenosine and the Regulation of RNA Localization and Function in the Brain.

A major challenge in neurobiology in the 21st century is to understand how the brain adapts with experience. Activity-dependent gene expression is integral to the synaptic plasticity underlying learning and memory; however, this process cannot be explained by a simple linear trajectory of transcription to translation within a specific neuronal population. Many other regulatory mechanisms can influence RNA metabolism and the capacity of neurons to adapt.

Publisher Correction: Dynamic regulation of Z-DNA in the mouse prefrontal cortex by the RNA-editing enzyme Adar1 is required for fear extinction.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Dynamic regulation of Z-DNA in the mouse prefrontal cortex by the RNA-editing enzyme Adar1 is required for fear extinction.

DNA forms conformational states beyond the right-handed double helix; however, the functional relevance of these noncanonical structures in the brain remains unknown. Here we show that, in the prefrontal cortex of mice, the formation of one such structure, Z-DNA, is involved in the regulation of extinction memory. Z-DNA is formed during fear learning and reduced during extinction learning, which is mediated, in part, by a direct interaction between Z-DNA and the RNA-editing enzyme Adar1.

The DNA modification N6-methyl-2'-deoxyadenosine (m6dA) drives activity-induced gene expression and is required for fear extinction.

DNA modification is known to regulate experience-dependent gene expression. However, beyond cytosine methylation and its oxidated derivatives, very little is known about the functional importance of chemical modifications on other nucleobases in the brain. Here we report that in adult mice trained in fear extinction, the DNA modification N6-methyl-2'-deoxyadenosine (m6dA) accumulates along promoters and coding sequences in activated prefrontal cortical neurons.

The DNA Repair-Associated Protein Gadd45γ Regulates the Temporal Coding of Immediate Early Gene Expression within the Prelimbic Prefrontal Cortex and Is Required for the Consolidation of Associative Fear Memory.

We have identified a member of the growth arrest and DNA damage (Gadd45) protein family, Gadd45γ, which is known to be critically involved in DNA repair, as a key player in the regulation of immediate early gene (IEG) expression underlying the consolidation of associative fear memory in adult male C57BL/6 mice. Gadd45γ temporally influences learning-induced IEG expression in the prelimbic prefrontal cortex (PLPFC) through its interaction with DNA double-strand break (DSB)-mediated changes in DNA methylation. Our findings suggest a two-hit model of experience-dependent IEG activity and learning that comprises (1) a first wave of IEG expression governed by DSBs and followed by a rapid increase in DNA methylation, and (2) a second wave of IEG expression associated with the recruitment of Gadd45γ and active DNA demethylation at the same site, which is necessary for memory consolidation.