Endogenous hydrogen peroxide positively regulates secretion of a gut-derived peptide in neuroendocrine potentiation of the oxidative stress response in <i>Caenorhabditis elegans</i>.

Abstract

The gut-brain axis mediates bidirectional signaling between the intestine and the nervous system and is critical for organism-wide homeostasis. Here, we report the identification of a peptidergic endocrine circuit in which bidirectional signaling between neurons and the intestine potentiates the activation of the antioxidant response in <i>Caenorhabditis elegans</i> in the intestine. We identify an FMRF-amide-like peptide, FLP-2, whose release from the intestine is necessary and sufficient to activate the intestinal oxidative stress response by promoting the release of the antioxidant FLP-1 neuropeptide from neurons. FLP-2 secretion from the intestine is positively regulated by endogenous hydrogen peroxide (H₂O₂) produced in the mitochondrial matrix by <i>sod-3</i>/superoxide dismutase, and is negatively regulated by <i>prdx-2</i>/peroxiredoxin, which depletes H₂O₂ in both the mitochondria and cytosol. H₂O₂ promotes FLP-2 secretion through the DAG and calcium-dependent protein kinase C family member <i>pkc-2</i> and by the SNAP25 family member <i>aex-4</i> in the intestine. Together, our data demonstrate a role for intestinal H₂O₂ in promoting inter-tissue antioxidant signaling through regulated neuropeptide-like protein exocytosis in a gut-brain axis to activate the oxidative stress response.