Addition of human melanopsin renders mammalian cells photoresponsive.

Journal article

A small number of mammalian retinal ganglion cells act as photoreceptors for regulating certain non-image forming photoresponses. These intrinsically photosensitive retinal ganglion cells express the putative photopigment melanopsin. Ablation of the melanopsin gene renders these cells insensitive to light; however, the precise role of melanopsin in supporting cellular photosensitivity is unconfirmed. Here we show that heterologous expression of human melanopsin in a mouse paraneuronal cell line (Neuro-2a) is sufficient to render these cells photoreceptive. Under such conditions, melanopsin acts as a sensory photopigment, coupled to a native ion channel via a G-protein signalling cascade, to drive physiological light detection. The melanopsin photoresponse relies on the presence of cis-isoforms of retinaldehyde and is selectively sensitive to short-wavelength light. We also present evidence to show that melanopsin functions as a bistable pigment in this system, having an intrinsic photoisomerase regeneration function that is chromatically shifted to longer wavelengths.

Authors: Melyan, Z; Tarttelin, E; Bellingham, J; Lucas, R; Hankins, M

• Publication status: Published
• Journal: Nature
• Volume: 433
• Issue: 7027
• Pages: 741-745
• Publication date: 2005-02-01
• DOI: 10.1038/nature03344
• EISSN: 1476-4687
• ISSN: 0028-0836
• Language: English
• Keywords: Calcium Signaling; Retinaldehyde; Gene Expression; Protein Isoforms; Light; Light Signal Transduction; Mice; Neurons; Animals; Rod Opsins; Cell Line; Humans; Cyclic GMP; Heterotrimeric GTP-Binding Proteins