Effect of fasting on transcription in intestinal cells dissected from adult C. elegans

Chromatin architecture is a fundamental mediator of genome function. Fasting is a major environmental cue across the animal kingdom. Yet, how it impacts on 3D genome organization is unknown. Here, we show that fasting induces an intestine-specific, reversible, and large-scale spatial reorganization of chromatin in C. elegans. This fasting-induced 3D genome reorganization requires inhibition of the nutrient-sensing mTOR pathway, through the regulation of RNA Pol I, but not Pol II nor Pol III, and is accompanied by remodeling of the nucleolus. By uncoupling the 3D genome configuration from the animal´s nutritional status we find that the spatial reorganization of chromatin correlates with the expression of metabolic and stress-related genes, potentially supporting the transcriptional response in fasted animals. Our work documents the first large-scale chromatin reorganization triggered by fasting and reveals that mTOR and RNA Pol I shape genome architecture in response to nutrients. RNA was extracted from intestines dissected from day 1 N2 wild type adults. Briefly, synchronized L1s by hypochlorite treatment were grown on OP50-seeded plates until day 1 of adulthood. Next, a fraction of adults was immediately dissected for the fed state, the rest was washed 3 times with M9 buffer for 10 minutes and fasted in M9 buffer for 12 hours on a roller at 20°C prior to intestine dissection.