title: Light-induced rapid Ca²⁺ response and MAPK phosphorylation in the cells heterologously expressing human OPN5.
abstract: Molecular imaging is a powerful tool for investigating intracellular signalling, but it is difficult to acquire conventional fluorescence imaging from photoreceptive cells. Here we demonstrated that human opsin5 (OPN5) photoreceptor mediates light-induced Ca(2+) response in human embryonic kidney (HEK293) and mouse neuroblastoma (Neuro2a) cell lines using a luminescence imaging system with a fluorescent indicator and a newly synthesized bioluminescent indicator. Weak light fluorescence and bioluminescence imaging revealed rapid and transient light-stimulated Ca(2+) release from thapsigargin-sensitive Ca(2+) stores, whereas long-lasting Ca(2+) elevation was observed using a conventional fluorescence imaging system. Bioluminescence imaging also demonstrated that OPN5 activation in HEK293 cells induced a decrease in pertussis toxin-sensitive cAMP, confirming previous reports. In addition, ultraviolet radiation induced the phosphorylation of mitogen-activated protein kinases when OPN5 was stimulated in Neuro2a cells. These findings suggest that the combination of these imaging approaches may provide a new means to investigate the physiological characteristics of photoreceptors.
authors.affiliation: Corporate R&D Center, Olympus Corporation, Tokyo, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Sugiyama
authors.affiliation: Corporate R&D Center, Olympus Corporation, Tokyo, Japan.
authors.forename: Hirobumi
authors.initials: H
authors.lastname: Suzuki
authors.affiliation: Corporate R&D Center, Olympus Corporation, Tokyo, Japan.
authors.forename: Takeo
authors.initials: T
authors.lastname: Takahashi
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism*; D045744:Cell Line, Tumor; D000242:Cyclic AMP / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D042541:Intracellular Space / Q000378:metabolism / Q000528:radiation effects; D008027:Light; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008856:Microscopy, Fluorescence; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D055355:Opsins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000528:radiation effects; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection
chemical_list: D008565:Membrane Proteins; C571119:OPN5 protein, human; D055355:Opsins; D000242:Cyclic AMP; D020928:Mitogen-Activated Protein Kinases; D002118:Calcium