Cell Metabolism paper shows that expression depends on proteins and sugars in the insects’ diet.
Researchers from Forschungszentrum Karlsruhe discovered a gene in flies involved in insuling signaling and whose expression depends upon the amount sugar in the insects’ diet.
In thier study, flies lacking insulin-producing cells showed reduced expression of the gene tobi (target of brain insulin), which encodes an evolutionarily conserved a-glucosidase enzyme that converts stored glycogen into glucose. They found that flies overexpressing the gene had lower levels of glycogen and showed growth defects.
They also found that tobi levels increased when flies consumed a protein-rich yeast paste and decreased when the insects ate a sugary concoction. The pattern of tobi expression is reminiscent of glucagon in mammals, according to the research team. They suggest that the gene may be controlled by an analogous hormone.
“Given the accumulating parallels between the islet-like cells of Drosophila and the pancreatic islets of mammals, it would not be surprising if this homeostatic mechanism and possibly others yet to be found is evolutionarily conserved between flies and humans,” writes Eric Rulifson, Ph.D., of the University of California, San Francisco, in an accompanying commentary to his paper published in the April issue of Cell Metabolism.