Dynamically expressed ELAV is required for learning and memory in bees

Changes in gene expression are a hallmark of learning and memory consolidation. Little is known about how alternative mRNA processing, particularly abundant in neuron-specific genes, contributes to these processes. Prototype RNA binding proteins of the neuronally expressed ELAV/Hu family are candidates for roles in learning and memory, but their capacity to cross-regulate and take over each others functions complicate substantiation of such links. Therefore, we focused on honey bees, which have only a single elav family gene. We find that honey bee elav contains a microexon, which is evolutionary conserved between invertebrates and humans. RNAi knockdown of elav demonstrates that ELAV is required for learning and memory in bees. Indicative of a role as immediate early gene, ELAV is dynamically expressed with altered alternative splicing and subcellular localization in mushroom bodies, but not in other brain parts. Expression and alternative splicing of elav change during memory consolidation illustrating an alternative mRNA processing program as part of a local gene expression response underlying memory formation. Although the honey bee genome encodes only a single elav gene, functional diversification is achieved by alternative splicing.