unc-8, a DEG/ENaC Family Member, Encodes a Subunit of a Candidate Mechanically Gated Channel That Modulates C. elegans Locomotion

Mechanically gated ion channels are important modulators of coordinated movement, yet little is known of their molecular properties. We report that C. elegans unc-8, originally identified by gain-of-function mutations that induce neuronal swelling and severe uncoordination, encodes a DEG/ENaC family member homologous to subunits of a candidate mechanically gated ion channel. unc-8 is expressed in several sensory neurons, interneurons, and motor neurons. unc-8 null mutants exhibit previously unrecognized but striking defects in the amplitude and wavelength of sinusoidal tracks inscribed as they move through an E. coli lawn. We hypothesize that UNC-8 channels could modulate coordinated movement in response to body stretch. del-1, a second DEG/ENaC family member coexpressed with unc-8 in a subset of motor neurons, might also participate in a channel that contributes to nematode proprioception.