Heat shock proteins function as signaling molecules to mediate neuron-glia communication in C. elegans during aging

The nervous system is primarily composed of neurons and glia, and the communication between them has profound roles in regulating the development and function of the brain. Neuron-glia signal transduction is known to be mediated by secreted signals through ligand-receptor interactions on the cell membrane. Here we show a new mechanism for neuron-glia signal transduction, wherein neurons transmit proteins to glia through extracellular vesicles, activating glial signaling pathways. We find that in the amphid sensory organ of Caenorhabditis elegans, different sensory neurons exhibit varying aging rates. This discrepancy in aging is governed by the cross-talk between neurons and glia. We demonstrate that early aged neurons can transmit heat shock proteins to glia via extracellular vesicles. These neuronal heat shock proteins activate the glial IRE1-XBP1 pathway, leading to the transcriptional regulation of chondroitin synthases to protect glia-embedded neurons from aging-associated functional decline. Therefore, our studies unveil a new mechanism for neuron-glia communication in the nervous system and provide new insights into our understanding of brain aging.