Organismal regulation of XBP-1-mediated unfolded protein response during development and immune activation.

The increased demand on protein folding in the endoplasmic reticulum (ER) during bacterial infection activates the unfolded protein response (UPR). OCTR-1--a G protein-coupled catecholamine receptor expressed in neurons--suppresses innate immunity by downregulating a non-canonical UPR pathway and the p38 MAPK pathway. Here, we show that OCTR-1 also regulates the canonical UPR pathway, which is controlled by XBP-1, at the organismal level. Importantly, XBP-1 is not under OCTR-1 control during development, only at the adult stage. Our results indicate that the nervous system temporally controls the UPR pathway to maintain ER homeostasis during development and immune activation.