GSE123507
A Persistence Detector for Metabolic Network Rewiring in an Animal
Biological systems must possess mechanisms that prevent inappropriate responses to spurious environmental inputs. Caenorhabditis elegans has two breakdown pathways for the short-chain fatty acid propionate: a canonical, vitamin B12-dependent pathway and a propionate-shunt that is used when vitamin B12 levels are low. The shunt pathway is kept off when there is sufficient flux through the canonical pathway, likely to avoid generating shunt-specific toxic intermediates. Here, we discover a transcriptional regulatory circuit that activates shunt gene expression upon propionate buildup. The nuclear hormone receptors NHR-10 and NHR-68 function together as a 'persistence detector' in a type 1, coherent feed-forward loop with an AND-logic gate to delay shunt activation upon propionate accumulation, and to avoid spurious shunt activation in response to a non-sustained pulse of propionate. Together, our findings identify the first persistence detector in an animal, which transcriptionally rewires propionate metabolism to maintain homeostasis. Overall design: C. elegans RNA-sequencing in wild type, nhr-10 deletion, or nhr-68 deletion animals treated with nothing, 20 nM vitamin B12, or 20 nM vitamin B12 and 40 mM propionate for 48 hours in duplicate.