Ecdysone signaling determines lateral polarity and remodels neurites to form Drosophila's left-right brain asymmetry.

Left-right (LR) asymmetry of the brain is fundamental to its higher-order functions. The Drosophila brain's asymmetrical body (AB) consists of a structural pair arborized from AB neurons and is larger on the right side than the left. We find that the AB initially forms LR symmetrically and then develops LR asymmetrically by neurite remodeling that is specific to the left AB and is dynamin dependent. Additionally, neuronal ecdysone signaling inhibition randomizes AB laterality, suggesting that ecdysone signaling determines AB's LR polarity. Given that AB's LR asymmetry relates to memory formation, our research establishes AB as a valuable model for studying LR asymmetry and higher-order brain function relationships. [Display omitted] • The AB is first formed as a bilateral structure in the Drosophila brain • Neurite pruning occurs in the left, but not right, AB during AB's lateralization • Lateralization of the AB depends on dynamin in neurons • Neuronal ecdysone signaling polarizes left-right asymmetry of the AB The asymmetrical body (AB) is a left-right (LR)-asymmetric structure in the Drosophila brain. Sakamura et al. show that the AB is initially formed LR symmetrically and lateralized though neurite remodeling during the pupal stage. This remodeling depends on dynamin activity in neurons. Ecdysone signaling defines LR polarity of the AB. [ABSTRACT FROM AUTHOR]