Profiling of presynaptic mRNAs reveals a role for axonal PUMILIOs in associative memory formation

Abstract

Presynaptic protein synthesis is important in the adult central nervous system; however, the set of mRNAs localized to presynaptic areas has yet to be identified in any organism. We differentially labeled somatic and synaptic compartments nervous system-wide in adult C. elegans and isolated synaptic regions for deep sequencing. Analysis of the synaptic transcriptome reveals that synaptic transcripts are predicted to have specialized functions in neurons. Differential expression analysis identified 543 genes enriched in synaptic regions relative to somatic regions, with synaptic functions conserved in higher organisms. We find that mRNAs for pumilio RNA-binding proteins are abundant in synaptic regions, which we confirmed through high-sensitivity in situ hybridization. We identified a new role for the PUM2 orthologs puf-7/8 as repressors of memory formation through regulation of the mitochondrial dynamics regulator, mff-1. Identification of presynaptic mRNAs provides insight into mechanisms that regulate synaptic function and behavior.

Behavioral screening of conserved RNA-binding proteins reveals CEY-1/YBX RNA-binding protein dysfunction leads to impairments in memory and cognition

“…Two classes of proteins known to control memory across species had multiple members represented in our screen candidates: the Pumilio and FBF RBP family ( pumilio1/2 orthologs puf-3 , puf-5 , puf-7 , and puf-8 ) as well as four proteins involved in translation initiation (eIF4/2α orthologs gcn-2, ife-1, ife-3, and drr-2 ). Pumilios have been linked to both LTM and working memory in Drosophila melanogaster and mice [64,65], and we have previously described their importance in C. elegans memory [58,63]. Similarly, eukaryotic translation initiation machinery eIF4E and eIF2α control memory formation, STM, and LTM in mice [66,67].…”

“…A single round of food-butanone training results in memory that persists for no longer than two hours in wild-type animals, and we asked if additional neuronal cey-1 increased the duration of this memory, as has been observed with other memory promoting genetic manipulations [28,29,63]. Worms with ( rab-3p::cey-1::rab-3 3’UTR; cey-1(+)) showed enhanced memory ( Figure 3F ), as their memory persists longer than the average two hours, consistent with previous memory enhancers [28,29,63]. Collectively, our results show that cey-1 is sufficient to increase memory when expressed only in the nervous system, suggesting that cey-1 is a memory enhancer.…”

“…To test this hypothesis, we determined whether increasing cey-1 expression in the nervous system would have beneficial effects on behavior. A single round of food-butanone training results in memory that persists for no longer than two hours in wild-type animals, and we asked if additional neuronal cey-1 increased the duration of this memory, as has been observed with other memory promoting genetic manipulations [28,29,63]. Worms with ( rab-3p::cey-1::rab-3 3’UTR; cey-1(+)) showed enhanced memory ( Figure 3F ), as their memory persists longer than the average two hours, consistent with previous memory enhancers [28,29,63].…”

“…After filtering this list based upon detection in C. elegans and mammalian synapses [55,[58][59][60][61][62], 313 RBPs met screening criteria. Of those, we proceeded with the top 20 most synaptically-enriched RBPs based on our previous work identifying the adult C. elegans synaptic transcriptome [58,63] for behavioral study.…”