Proteome Analysis of Drosophila Mutants Identifies a Regulatory Role for 14-3-3ε in Metabolic Pathways

The evolutionary conserved family of 14-3-3 proteins appears to have a role in integrating numerous intracellular pathways, including signal transduction, intracellular trafficking, and metabolism. However, little is known about how this interactive network might be affected by the direct abrogation of 14-3-3 function. The loss of Drosophila 14-3-3 epsilon resulted in reduced survival of mutants during larval-to-adult transition, which is known to depend on an energy supply coming from the histolysis of fat body tissue. Here we report a differential proteomic analysis of larval fat body tissue at the onset of larval-to-adult transition, with the loss of 14-3-3 epsilon resulting in the altered abundance of 16 proteins. These included proteins linked to protein biosynthesis, glycolysis, tricarboxylic acid cycle, and lipid metabolic pathways. The ecdysone receptor (EcR), which is responsible for initiating the larval-to-adult transition, colocalized with 14-3-3 epsilon in wild-type fat body tissues. The altered protein abundance in 14-3-3 epsilon mutant fat body tissue was associated with transcriptional deregulation of alcohol dehydrogenase, fat body protein 1, and lamin genes, which are known targets of the EcR This study indicates that 14-3-3 epsilon has a critical role in cellular metabolism involving either molecular crosstalk with the EcR or direct interaction with metabolic proteins.