The Drosophila melanogaster tribbles pseudokinase is necessary for proper memory formation

The tribbles (trbl) pseudokinases play important roles in signaling and physiology in multiple contexts, ranging from innate immunity to cancer, suggesting fundamental cellular functions for the trbls' gene products. Despite expression of the trbl pseudokinases in the nervous systems of invertebrate and vertebrate animals, and evidence that they have a function within mouse and human dopamine neurons, there is no clear case for a function of a Trbl protein that influences behavior. Indeed, the first and only evidence for this type of function comes from Drosophila melanogaster, where a mutation of the single trbl gene was identified in a genetic screen for short-term memory mutant flies. The current study tested flies containing multiple trbl mutant alleles and potential transgenic rescue in both operant place memory and classical olfactory memory paradigms. Genetic complementation tests and transgenic rescue of memory phenotypes in both paradigms show that the D. melanogaster trbl pseudokinase is essential for proper memory formation. Expression analysis with a polyclonal antiserum against Trbl shows that the protein is expressed widely in the fly brain, with higher expression in the cellular rind than the neuropil. Rescue of the behavioral phenotype with transgenic expression indicates the trbl function can be localized to a subset of the nervous system. Thus, we provide the first compelling case for the function of a trbl pseudokinase in the regulation of behavior.