Inhibit and conquer: the passage to adulthood in Drosophila

A group of researchers at the Institute for Evolutionary Biology (IBE: CSIC-UPF) has determined that the transition from pupa to adulthood in the fruit fly begins when the E93 gene represses the Broad gene, which is responsible for pupal development. Previous studies had concluded that the E93 gene activated developmental processes in the adult stage of the fly (Drosophila melanogaster). However, this study, in which researchers from the Centre for Genomic Regulation (CRG) have also participated, has shown that the expression of the Broad gene blocks adult development. Once the E93 gene inhibits the Broad gene, the fly reaches adulthood.

The study analyses at the gene level the fly’s metamorphosis and the relationship of the three main genes involved in it, Chinmo, Broad and E93. The first is responsible for development during the larval stage, the fly’s juvenile period, while the other two are associated with the pupal and adult stages, respectively. The study has determined that the Broad gene also prevents the pupal phase processes from starting too early, i.e. in the larval stage. Josefa Cruz, first author of the article, says that ‘the Broad gene is a “Peter Pan” gene that keeps the insect in an intermediate phase between juvenile and adult stages, giving time for the organs to develop correctly before the transition to adulthood’.

The study of the mechanisms of activation and inhibition of these genes may be key to understanding the development of cancer in some cases. The genes homologous to Broad, E93 and Chinmo in humans play a fundamental role in cancerous processes. The gene in the juvenile stage is responsible for promoting tissue growth. In contrast, those of later stages function in humans as tumour suppressors, limiting uncontrolled proliferation and promoting cell maturation. Understanding the relationship between them may open doors to new cancer therapies based on the processes of cell division and differentiation, as well as offer new insights into human evolution.