Researchers have identified the complete series of 10 factors that regulate the development of brain cell types in the visual system of fruit flies—including in what order these neurons develop. The findings, published in Nature, open new avenues of research to understand how brain development evolved in different animals and hold clues for regenerative medicine.
Confocal microscopy image of the developing fruit fly visual system showing stem cells expressing different temporal transcription factors (shown in different colors) as they age. Each of these temporal windows of expression produces different neurons, thus generating neuronal diversity. Credit: Isabel Holguera, Desplan Laboratory, NYU
“Knowing how the human brain develops could allow us in the future to repeat these developmental processes in the lab to generate specific types of neurons in a Petri dish—and potentially transplant them in patients—or to trigger neuronal stem cells in living organisms to generate and replace missing neurons,” said Claude Desplan, Silver Professor of Biology at NYU and the study’s senior author.
A mechanism by which neural stem cells produce different neurons over time is called temporal patterning. By expressing different molecules—termed temporal transcription factors, or tTFs—that regulate the expression of specific genes in each window of time, neural stem cells produce different neurons.
In the research published in Nature, the researchers studied the brains of the fruit fly Drosophila to uncover the complete set of tTFs needed to generate the roughly 120 neuron types of the medulla, a specific brain structure in the visual system of flies. They used state-of-the-art single-cell mRNA sequencing to obtain the transcriptome—all of the genes expressed in a given cell—of more than 50,000 individual cells that were then grouped into most of the cell types present in the developing medulla.