Scientists from UCL and the Francis Crick Institute have uncovered a hidden communication system that allows cells to determine their identity with remarkable precision. The study reveals how morphogens, molecules that provide positional information during development, combine with other cellular signals to guide cells toward specific fates.
The research examined the developing visual system of the fruit fly Drosophila melanogaster, where groups of precursor cells must become different types of neurons in an exact arrangement. Researchers found that precursor cells dynamically integrate multiple signals, the morphogen Hedgehog, Notch and ERK signalling pathways, to refine developmental decisions at the level of individual cells.
Morphogens usually create concentration gradients that tell cells where they are located and what they should become. However, the study shows that the information provided by these gradients can be enhanced by additional signals. In the fly visual system, non-neuronal cells called glia activate ERK signalling in naïve neuronal precursor cells. This leads to a stable pattern of differential Notch pathway activity among the precursor cells, which in turn subdivides the broad morphogen-driven regions into smaller zones that take on distinct cell identities.
The researchers discovered that Notch signalling also controls a Hedgehog morphogen relay, preventing the source of Hedgehog from spreading too far. By restricting which cells can produce more Hedgehog, Notch helps maintain accurate patterns and prevents incorrect cell fate decisions.
Combining genetic experiments with mathematical modelling, the teams showed that precise development depends not only on which signals are present, but also on when they appear. Glial cells act as developmental timers, scheduling cell fate decisions with the appropriate Hedgehog and Notch activity to create reliable patterns across developing tissues.
The findings highlight a broader principle in biology: cells do not rely on a single instruction. Instead, they integrate multiple signals, including morphogens, contact-based communication and timing cues, to build complex tissues with accuracy and resilience.
Links
Research article in Current Biology
Vilaiwan Fernandes UCL Profile