UNC-1 Regulates Gap Junctions Important to Locomotion in C. elegans

• DOI: 10.1016/j.cub.2007.06.060
• Publication Date: 2007-07-20T13:38:22Z
• Authors: Bojun Chen; Qiang Liu; Qian Ge; Jia Xie; Zhao-Wen Wang
• Keywords: Neurons; Muscle Cells; Agricultural and Biological Sciences(all); Biochemistry, Genetics and Molecular Biology(all); Molecular Sequence Data; Animals; Gap Junctions; Membrane Proteins; SYSNEURO; Caenorhabditis elegans; Caenorhabditis elegans Proteins; Locomotion

In C. elegans, loss-of-function (lf) mutations of the stomatin-like protein (SLP) UNC-1 and the innexin UNC-9 inhibit locomotion [1, 2] and modulate sensitivity to volatile anesthetics [3, 4]. It was unknown why unc-1(lf) and unc-9(lf) mutants have similar phenotypes. We tested the hypothesis that UNC-1 is a regulator of gap junctions formed by UNC-9. Analyses of junctional currents between body-wall muscle cells showed that electrical coupling was inhibited to a similar degree in unc-1(lf), unc-9(lf), and unc-1(lf);unc-9(lf) double mutants, suggesting that UNC-1 and UNC-9 function together. Expression of Punc-1::DsRED2 and Punc-9::GFP transcriptional fusions suggests that unc-1 and unc-9 are coexpressed in neurons and body-wall muscle cells. Immunohistochemistry showed that UNC-1 and UNC-9 colocalized at intercellular junctions and that unc-1(lf) did not alter UNC-9 expression or subcellular localization. Bimolecular fluorescence complementation (BiFC) assays suggest that UNC-1 and UNC-9 are physically very close at intercellular junctions. Targeted rescue experiments suggest that UNC-9 and UNC-1 function predominantly in neurons to control locomotion. Thus, in addition to the recently reported function of regulating mechanosensitive ion channels [5, 6], SLPs might have a novel function of regulating gap junctions.