The RNA-guided Cas9 nuclease, from the type II prokaryotic clustered regularly interspersed short palindromic repeats (CRISPR) adaptive immune system, has been adapted by scientists to enable site specific genome editing of eukaryotic cells both in vitro and in vivo. Previously, we reported the development of an adeno-associated virus (AAV)-mediated CRISPR Streptococcus pyogenes (Sp) Cas9 system, in which the genome editing function can be regulated by controlling the expression of the guide RNA (sgRNA) in a doxycycline (Dox)-dependent manner. Here, we report the development of an AAV vector tool kit utilizing the Cas9 from Staphylococcus aureus (SaCas9). We demonstrate in vitro genome editing in human derived 293FT cells and mouse derived Neuro2A (N2A) cells and in vivo in neurons of the mouse brain. We also demonstrate the ability to regulate the induction of genome editing temporally with Dox and spatially with Cre-recombinase. The combination of these systems enables AAV-mediated CRISPR/Cas9 genome editing to be regulated both spatially and temporally.

The synaptic proteins cerebellin-1 and neurexin-1β permit ion channel activity in delta subtype of ionotropic glutamate receptors.

No abstract

Kainate receptors are members of the ionotropic glutamate receptor family. They form cation-specific transmembrane channels upon binding glutamate that desensitize in the continued presence of agonists. Concanavalin A (Con-A), a lectin, stabilizes the active open-channel state of the kainate receptor and reduces the extent of desensitization. In this study, we used single-molecule fluorescence resonance energy transfer (smFRET) to investigate the conformational changes underlying kainate receptor modulation by Con-A. These studies showed that Con-A binding to GluK2 homomeric kainate receptors resulted in closer proximity of the subunits at the dimer–dimer interface at the amino-terminal domain as well as between the subunits at the dimer interface at the agonist-binding domain. Additionally, the modulation of receptor functions by monovalent ions, which bind to the dimer interface at the agonist-binding domain, was not observed in the presence of Con-A. Based on these results, we conclude that Con-A modulation of kainate receptor function is mediated by a shift in the conformation of the kainate receptor toward a tightly packed extracellular domain.

Running title: Increasing synaptic GluN2B enhances memory modification Number of words in Abstract = 248 Number of words in the text (excluding abstract, acknowledgments and financial disclosures sections, legends, and references) = 3805 Number of tables = 0 Number of figures = 5 Number of supplementary material = 1 AbstractReconsolidation disruption has been proposed as a method to attenuate pathological memories in disorders such as PTSD. However, studies from our group and others indicate that strong memories are resistant to becoming destabilized following reactivation, rendering them impervious to agents that disrupt the re-stabilization phase of reconsolidation. Thus, therapies designed to attenuate maladaptive memories by disrupting reconsolidation updating have not been adequately developed. We previously determined that animals possessing strong auditory fear memories, compared to animals with weaker fear memories, are associated with an enduring increase in the synaptic GluN2A/GluN2B ratio in neurons of the mouse basal and lateral amygdala (BLA). In this study, we determined whether increasing GluN2B levels within BLA excitatory neuronal synapses is sufficient to enable modification of strong fear memories via reconsolidation. To accomplish this, we utilized a combinatorial genetic strategy to express GluN2B or GluN2B(E1479Q) in excitatory neurons of the mouse BLA before or after fear memory consolidation. GluN2B(E1479Q) contains a point mutation that increases synaptic expression of the subunit by interfering with phosphorylation-driven endocytosis. At the time of memory retrieval, increasing synaptic GluN2B levels by expression of GluN2B(E1479Q), but not GluN2B(WT), enhanced the induction of reconsolidation rendering the strong fear memory modifiable. GluN2B(WT) or GluN2B(E1479Q) expression did not influence fear memory maintenance or extinction. Fear memory consolidation, however, was enhanced when GluN2B(E1479Q) was expressed in the BLA at the time of training. These findings indicate that enhancing GluN2B synaptic trafficking may provide a novel therapeutic strategy to enhance modification of pathological memories.