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Nature. 2005 Feb 17;433(7027):741-5. Epub 2005 Jan 26.

Addition of human melanopsin renders mammalian cells photoresponsive.

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  • 1Department of Visual Neuroscience, Division of Neuroscience and Psychological Medicine, Imperial College London, Charing Cross Hospital Campus, Fulham Palace Road, London W6 8RF, UK.

Abstract

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.

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PMID:
15674244
[PubMed - indexed for MEDLINE]
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