The secret of insect youth and maturity lies in just a few specific genes, genes that are also present in humans. Imagine being able to understand these genetic mechanisms and their potential impact on us humans.
A recent study published in the journal eLife and led by the Institute for Evolutionary Biology (IBE, CSIC-UPF) and IRB Barcelona discovered the fundamental role of the chinmo gene in insect development. In addition, two other genes, Br-C and E93, regulate the maturity of these insects. These three genes also occur in humans and influence the development of cancer processes there, either by promoting or inhibiting them.
The absence of chinmo in cells reduces wing growth (left) compared to control wing progenitor tissue (middle), while overexpression of the chinmo gene induces tissue overgrowth, as occurs in tumor processes (right).
Photo credit: IBE
The study focused on the fruit fly (Drosophila melanogaster) and the German cockroach (Blattella germanica). The results show that these genes were conserved throughout insect evolution. Thus, they probably play a key role in the phenomenon of metamorphosis.
In the development cycle of insects that undergo complete metamorphosis, such as the fly, three main stages can be distinguished: the embryo, which forms inside the egg; the larva (juvenile stage), which grows in several stages; and the pupa, which represents the phase of metamorphosis and formation of the adult organism.
The Br-C gene has been shown to determine pupal formation in insects. Similarly, in 2019, the IBE team had shown that the E93 gene is essential to complete insect metamorphosis and initiate the maturation of tissues destined for adult formation. As for the Chinmo gene, it is he who controls the juvenile stage of these organisms.
When the researchers deleted the chinmo gene in Drosophila specimens, they found that these insects reached the pupal stage without completing the juvenile stage and progressed to the adult stage prematurely. This proves that the chinmo gene is essential for youth development.
Dr other genes responsible for the formation of adult tissue.
In order for Drosophila to move from the juvenile phase to the pupal phase and successfully undergo their metamorphosis, it is necessary to inactivate the chinmo gene. The study confirms that the sequential action of these three genes, Chinmo, Br-C and E93, coordinates the formation of the various organs that make up the adult organism.
The BTB-ZF transcription factor family, which includes Chinmo and Br-C, also plays a crucial role in cancer processes. These proteins are also found in humans. While Chinmo promotes tissue growth and prevents differentiation, the C-Br and E93 genes act as tumor suppressors by activating tissue maturation.
The complete metamorphosis of insects such as butterflies and flies is an evolutionary innovation that came about gradually. “It’s fascinating to see how evolution works by analyzing these genes in different insect species. The fact that chinmo function is preserved in insects as distant as flies and cockroaches gives us clues as to the origin of the metamorphoses,” explains Dr. David Martin, co-leader of the study.