Biogenesis of GPI-anchored proteins is essential for surface expression of sodium channels in zebrafish Rohon-Beard neurons to respond to mechanosensory stimulation.
In zebrafish, Rohon-Beard (RB) neurons are primary sensory neurons present during the embryonic and early larval stages. At 2 days post-fertilization (dpf), wild-type zebrafish embryos respond to mechanosensory stimulation and swim away from the stimuli, whereas mi310 mutants are insensitive to touch. During approximately 2-4 dpf, wild-type RB neurons undergo programmed cell death, which is caused by sodium current-mediated electrical activity, whereas mutant RB cells survive past 4 dpf, suggesting a defect of sodium currents in the mutants. Indeed, electrophysiological recordings demonstrated the generation of action potentials in wild-type RB neurons, whereas mutant RB cells failed to fire owing to the reduction of voltage-gated sodium currents. Labeling of dissociated RB neurons with an antibody against voltage-gated sodium channels revealed that sodium channels are expressed at the cell surface in wild-type, but not mutant, RB neurons. Finally, in mi310 mutants, we identified a mis-sense mutation in pigu, a subunit of GPI (glycosylphosphatidylinositol) transamidase, which is essential for membrane anchoring of GPI-anchored proteins. Taken together, biogenesis of GPI-anchored proteins is necessary for cell surface expression of sodium channels and thus for firings of RB neurons, which enable zebrafish embryos to respond to mechanosensory stimulation.
Nakano
Yuri
Y
Graduate School of Science, Nagoya University, Nagoya, Japan.
Fujita
Morihisa
M
Ogino
Kazutoyo
K
Saint-Amant
Louis
L
Kinoshita
Taroh
T
Oda
Yoichi
Y
Hirata
Hiromi
H
D000818:Animals; D030801:Animals, Genetically Modified; D000954:Antigens, Surface / Q000378:metabolism; D016466:CHO Cells; D016923:Cell Death / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D006224:Cricetinae; D003412:Cricetulus; D004625:Embryo, Nonmammalian; D055785:Gene Knockdown Techniques; D017261:Glycosylphosphatidylinositols / Q000096:biosynthesis / Q000378:metabolism*; D040542:Mechanotransduction, Cellular / Q000235:genetics*; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000378:metabolism / Q000502:physiology; D010812:Physical Stimulation; D034741:RNA, Small Interfering / Q000494:pharmacology; D011984:Sensory Receptor Cells / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D015222:Sodium Channels / Q000378:metabolism*; D015027:Zebrafish / Q000196:embryology / Q000235:genetics* / Q000378:metabolism
D000954:Antigens, Surface; D017261:Glycosylphosphatidylinositols; D008565:Membrane Proteins; D034741:RNA, Small Interfering; D015222:Sodium Channels