C. elegans phototransduction requires a G protein-dependent cGMP pathway and a taste receptor homolog.
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.
Liu
Jie
J
Life Sciences Institute, Department of Molecular and Integrative Physiology, and Neuroscience Program, University of Michigan, Ann Arbor, Michigan, USA.
Ward
Alex
A
Gao
Jingwei
J
Dong
Yongming
Y
Nishio
Nana
N
Inada
Hitoshi
H
Kang
Lijun
L
Yu
Yong
Y
Ma
Di
D
Xu
Tao
T
Mori
Ikue
I
Xie
Zhixiong
Z
Xu
X Z Shawn
XZ
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
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