title: C. elegans phototransduction requires a G protein-dependent cGMP pathway and a taste receptor homolog.
abstract: The eyeless animal C. elegans is able to sense light and engages in phototaxis behavior that is mediated by photoreceptor cells. However, the molecular and cellular mechanisms underlying phototransduction in C. elegans remain largely unclear. By recording the photoreceptor neuron ASJ in wild-type and various mutant worms, we found that phototransduction in ASJ is a G protein-mediated process and requires membrane-associated guanylate cyclases, but not typical phosphodiesterases. In addition, we found that C. elegans phototransduction requires LITE-1, a candidate photoreceptor protein known to be a member of the invertebrate taste receptor family. Our genetic, pharmacological and electrophysiological data suggest a model in which LITE-1 transduces light signals in ASJ via G protein signaling, which leads to upregulation of the second messenger cGMP, followed by opening of cGMP-sensitive CNG channels and stimulation of photoreceptor cells. Our results identify a phototransduction cascade in C. elegans and implicate the function of a 'taste receptor' in phototransduction.
authors.affiliation: Life Sciences Institute, Department of Molecular and Integrative Physiology, and Neuroscience Program, University of Michigan, Ann Arbor, Michigan, USA.
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
authors.forename: Alex
authors.initials: A
authors.lastname: Ward
authors.forename: Jingwei
authors.initials: J
authors.lastname: Gao
authors.forename: Yongming
authors.initials: Y
authors.lastname: Dong
authors.forename: Nana
authors.initials: N
authors.lastname: Nishio
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Inada
authors.forename: Lijun
authors.initials: L
authors.lastname: Kang
authors.forename: Yong
authors.initials: Y
authors.lastname: Yu
authors.forename: Di
authors.initials: D
authors.lastname: Ma
authors.forename: Tao
authors.initials: T
authors.lastname: Xu
authors.forename: Ikue
authors.initials: I
authors.lastname: Mori
authors.forename: Zhixiong
authors.initials: Z
authors.lastname: Xie
authors.forename: X Z Shawn
authors.initials: XZ
authors.lastname: Xu
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D017173:Caenorhabditis elegans; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D006152:Cyclic GMP / Q000378:metabolism*; D054815:Cyclic Nucleotide-Gated Cation Channels / Q000378:metabolism; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006162:Guanylate Cyclase / Q000378:metabolism; D055537:Light Signal Transduction / Q000502:physiology*; D008564:Membrane Potentials / Q000502:physiology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008959:Models, Neurological; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism; D009474:Neurons / Q000502:physiology; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism; D010775:Photic Stimulation; D017956:Photoreceptor Cells, Invertebrate / Q000502:physiology*; D015398:Signal Transduction; D015854:Up-Regulation
chemical_list: D029742:Caenorhabditis elegans Proteins; D054815:Cyclic Nucleotide-Gated Cation Channels; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; C532483:lite-1 protein, C elegans; D010727:Phosphoric Diester Hydrolases; D019204:GTP-Binding Proteins; D006162:Guanylate Cyclase; D006152:Cyclic GMP