Regulation of brain gene expression in honey bees by brood pheromone

Pheromones are very important in animal communication. To learn more about the molecular basis of pheromone action, we studied the effects of a potent honey bee pheromone on brain gene expression. Brood pheromone (BP) caused changes in the expression of hundreds of genes in the bee brain in a manner consistent with its known effects on behavioral maturation. Brood pheromone exposure in young bees causes a delay in the transition from working in the hive to foraging, and we found that BP treatment tended to upregulate genes in the brain that are upregulated in bees specialized on brood care but downregulate genes that are upregulated in foragers. However, the effects of BP were age dependent; this pattern was reversed when older bees were tested, consistent with the stimulation of foraging by BP in older bees already competent to forage. These results support the idea that one way that pheromones influence behavior is by orchestrating large-scale changes in brain gene expression. We also found evidence for a relationship between cis and BP regulation of brain gene expression, with several cis-regulatory motifs statistically overrepresented in the promoter regions of genes regulated by BP. Transcription factors that target a few of these motifs have already been implicated in the regulation of bee behavior. Together these results demonstrate strong connections between pheromone effects, behavior, and regulation of brain gene expression.