Stem cell intrinsic nutrient sensing regulating diet dependent intestinal adaptation

The intestine is an organ with exceptionally high rate of cell turnover and perturbations in this process can lead to disease such as cancer or intestinal atrophy. Nutrition is a key factor regulating the intestinal cell turnover and has a profound impact on intestinal volume and cellular architecture. However, how the intestinal equilibrium is maintained in fluctuating dietary conditions is insufficiently understood. By utilizing the Drosophila midgut as a model, we reveal a novel nutrient sensing mechanism coupling stem cell metabolism with stem cell extrinsic growth signal. Our results show that intestinal stem cells (ISCs) employ the hexosamine biosynthesis pathway (HBP) to monitor nutritional status and energy metabolism. Elevated activity of the HBP promotes Warburg effect-like metabolic reprogramming, which is required for the reactivation of ISCs from calorie restriction-induced quiescence. Furthermore, the HBP activity is an essential facilitator for insulin signaling-induced intestinal growth. In conclusion, intestinal stem cell intrinsic nutrient sensing regulates metabolic pathway activities, and defines the stem cell responsiveness to niche-derived growth signals.