GrowthDevStability · Characterization of the developmental mechanisms ensuring a robust symmetrical growth in the bilateral model organism Drosophila melanogaster

Characterization of the developmental mechanisms ensuring a robust symmetrical growth in the bilateral model organism Drosophila melanogaster

Most animals, including humans, have one longitudinal or sagittal plane which divides the organism into two roughly mirror images, the left and right halves. For example, the surfaces of the two wings of the fruit fly Drosophila melanogaster, a privileged model organism, do not differ by more than 2% in wild-type animals. This feature is called Bilateral Symmetry and constitutes a key quality that defines mobility, predation and overall fitness. Even though many studies have focused on the autonomous mechanisms of organ size determination, less attention has been put on how organ growth is coordinated between the left and right halves in order to attain Bilateral Symmetry. The fact that symmetry is achieved even in the case of illness, starvation and injuries, suggests the occurrence of dedicated mechanisms that are able to compare the growth trajectories of each half and adjust when required. The investigation on how Bilateral Symmetry is achieved has profound impacts, not only because it constitutes a fundamental question in Developmental Biology but also because it is directly linked to animal and human health and technology. The new concepts introduced by this investigation could help to better understand the pathophysiology of childhood growth disorders, as well as the growth disturbances observed in cancer survivors. It would also certainly have implications for large-scale regenerative research, in which a tight coordination of left and right halves should be attained. The overarching objective of the proposed project was to find how and when organs asses their growth status in Drosophila, and which mechanisms are deployed to ensure fine size adjustment during normal animal development. In particular, my research was focused of the role of a signaling peptide that belongs to the superfamily of insulin/IGF/relaxin-like peptidic hormones and is called Drosophila insulin-like peptide 8 (Dilp8). I sought to characterize the source tissue that produces dilp8, how and when this production is induced, and what are the downstream events that dilp8 triggers for bilateral organ size adjustment. After my two years of MSCA-funded research, the research team and I were able to define a cross-talk between Dilp8 and the growth-regulating hormone ecdysone that is key for developmental precision. This cross-talk has two functions: (i) it defines a critical time window after larval development during which wings adjust their size; (ii) it fine-tunes the levels of ecdysone signaling in the discs, which is crucial for their size adjustment.

Data: CORDIS, © European Union