A FMRF-amide peptide that regulates cell non-autonomous protein homeostasis in C. elegans.

The coordination of protein homeostasis from the brain to periphery is essential for the health and survival of all animals. In C. elegans, glia serve a central role in coordinating organismal protein homeostasis and longevity via the unfolded protein response of the endoplasmic reticulum (UPRER). However, the full extent of the cell non-autonomous response and the identity of the signaling molecules required remained unknown. Here, we show that glial UPRER activation induces robust transcriptomic changes in specific tissue types across the animal, particularly in pathways related to neuropeptide signaling. We performed neuropeptidomics and loss and gain-of-function genetic screens and identified a single neuropeptide, FLP-17, that is sufficient but not necessary to induce cell non-autonomous activation of the UPRER. FLP-17 is sufficient to protect against chronic ER stress and age-dependent protein aggregation. We determined that FLP-17 acts through the receptor, EGL-6, to activate cell non-autonomous UPRER. This work reveals a complex peptidergic signaling network initiated by glial activation of the UPRER to regulate organismal protein homeostasis.