Project description:The hippocampal formation is a brain structure essential for higher-order cognitive functions. It has exquisite differences in anatomical organization and cellular composition, and hippocampal sub-regions have different properties and functional roles. Areas CA1 and CA3 in particular, are key sub-regions for learning and memory formation that fulfill complementary but specific functions. The molecular basis for such specific properties and the link to learning and memory remain unknown. Here using a SWATH-MS proteomic approach and bioinformatic tools, we identify a selective proteomic signature in area CA1 and CA3, and reveal their specific dynamics during memory formation. We show that 30% of all quantifiable proteins are differentially expressed in area CA1 and CA3 at baseline, and that each proteome responds differently during the formation of memory for object or object location. Using clustering and cross-correlational analyses, we outline specific temporal proteomic profiles and an increased correlation between both forms of memory within area CA1, but not within area CA3. These results provide new insight into a proteomic basis for hippocampal sub-region molecular and functional specificity.
Project description: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 Gas5 variant that accumulate in the synaptic compartment within the infralimbic prefrontal cortex of adult male C57/Bl6 mice. Gas5 RNA immunoprecipitation followed by mass spectrometry revealed that this Gas5 isoform, in association with the RNA binding proteins G3BP2 and CAPRIN1, regulates the activity-dependent trafficking and clustering of RNA granules. In addition, we found that cell-type-specific, activity-dependent, and synapse-specific knockdown of this Gas5 variant led to impaired fear extinction memory. These findings identify a new mechanism of fear extinction that involves the dynamic interaction between local lncRNA activity and RNA condensates in the synaptic compartment.
