One of the most striking examples of gut plasticity can be seen in animals that are subjected to prolonged periods of fasting, such as hibernating animals or phyton snakes that go months without eating, where the gut shrinks by up to 50 per cent but recovers in size after a few days of refeeding.

The Colombani Andersen lab at the section of Cell & Neurobiology, Department of Biology, University of Copenhagen uses the experimental model, Drosophila, to study the mechanisms that regulate gut plasticity. The results have just been published in the scientific journal Nature Communications.

Importantly, the gut's ability to resize is largely retained. As a result, during pregnancy in humans, gut size increases, facilitating nutrition intake to promote foetal development.

"Taking advantage of the broad genetic toolbox available in the experimental model, we have investigated the mechanisms underpinning nutrient-dependent gut resizing", says Dr. Ditte S. Andersen.

The results show that nutrient deprivation results in an accumulation of progenitor cells that fail to differentiate into the mature cells causing the gut to shrink.

Upon refeeding these stalled progenitor cells readily differentiate into mature cells to promote regrowth of the gut.

Ditte S. Andersen continues, "We have identified activins as critical regulators of this process. In nutrient-restrictive conditions, activin signalling is strongly repressed, while it is reactivated and required for progenitor maturation and gut resizing in response to refeeding. Activin-dependent resizing of the gut is physiologically important as inhibition of activin signalling reduces survival of the experimental model to intermittent fasting."

Regulators of organ plasticity are essential for host adaptation to an ever-changing environment, however, the same signals are often deregulated in cancers. Indeed, mutations affecting activin signalling are frequent in cancer cells in a variety of tissues.

Our study provides a starting point for investigating the link between aberrant activin signalling and the development of colorectal cancers and sets the stage for exploring the efficiency of anti-activin therapeutic strategies in treating colorectal cancers.