Shear stress sensing in C. elegans.

Shear stress sensing represents a vital mode of mechanosensation.¹ Previous efforts have mainly focused on characterizing how various cell types-for example, vascular endothelial cells-sense shear stress arising from fluid flow within the animal body.^1,2 How animals sense shear stress derived from their external environment, however, is not well understood. Here, using C. elegans as a model, we show that external fluid flow triggers behavioral responses in C. elegans, facilitating their navigation of the environment during swimming. Such behavioral responses primarily result from shear stress generated by fluid flow. The sensory neurons AWC, ASH, and ASER are the major shear stress-sensitive neurons, among which AWC shows the most robust response to shear stress and is required for shear stress-induced behavior. Mechanistically, shear stress signals are transduced by G protein signaling in AWC, with cGMP as the second messenger, culminating in the opening of cGMP-sensitive cyclic nucleotide-gated (CNG) channels and neuronal excitation. These studies demonstrate that C. elegans senses and responds to shear stress and characterize the underlying neural and molecular mechanisms. Our work helps establish C. elegans as a genetic model for studying shear stress sensing.