Addition of human melanopsin renders mammalian cells photoresponsive

@article{Melyan2005AdditionOH,
  title={Addition of human melanopsin renders mammalian cells photoresponsive},
  author={Zare Melyan and Emma E. Tarttelin and James Bellingham and Robert James Lucas and M. W. Hankins},
  journal={Nature},
  year={2005},
  volume={433},
  pages={741-745}
}
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… 

Photochemistry of retinal chromophore in mouse melanopsin

Results indicate that even if melanopsin functions as a bistable photopigment with photo-regenerative activity native melanops in vivo must also use some other light-independent retinoid regeneration mechanism to return to the dark state, where all of the retinal is observed to be in the 11-cis form.

Photochemical properties of mammalian melanopsin.

A new state of melanopsin, containing 7-cis-retinal (extramelanopsin), which forms readily upon long-wavelength irradiation and photoconverts to metamelanops in with short-wa wavelength (blue light) irradiation is found.

Melanopsin phototransduction: beyond canonical cascades

Recent findings and discoveries are discussed that have challenged the prevailing view of melanopsin phototransduction as a single pathway that influences solely non-image forming functions.

Induction of photosensitivity by heterologous expression of melanopsin

It is concluded that mammalian melanopsin is a functional sensory photopigment, that it is the photopigsment of ganglion-cell photoreceptors, and that these photoreCEPTors may use an invertebrate-like phototransduction cascade.

Melanopsin Bistability: A Fly's Eye Technology in the Human Retina

The results suggest that the human retina exploits fly-like photoreceptive mechanisms that are potentially important for the modulation of non-visual responses to light and highlights the ubiquitous nature of photoswitchable photosensors across living organisms.

Intrinsically photosensitive retinal ganglion cells detect light with a vitamin A-based photopigment, melanopsin.

  • Yingbin FuH. Zhong K. Yau
  • Biology
    Proceedings of the National Academy of Sciences of the United States of America
  • 2005
Study of mice lacking RPE65, a protein essential for the regeneration of rod and cone pigments, and exogenous all-trans-retinal was also able to rescue the low sensitivity of rpe65-/- ipRGCs suggest melanopsin could be a bistable pigment.

Phototransduction in Retinal Ganglion Cells

  • P. Detwiler
  • Biology
    The Yale journal of biology and medicine
  • 2018
None of the molecular elements in the melanopsin transduction process have been unequivocally identified, giving rise to the possibility that the underlying mechanism responsible for intrinsic photosensitivity is not same in all ipR GC sub-types and to the recognition that signal transduction in ipRGCs is more complex than originally thought.

Small molecule antagonists of melanopsin-mediated phototransduction

The identification of a potent synthetic melanopsin antagonist with in vivo activity is described and the discovery of opsinamides raises the prospect of therapeutic control of the melanopsIn phototransduction system to regulate light-dependent behavior and remediate pathological conditions.

Chromophore regeneration: Melanopsin does its own thing

  • R. Lucas
  • Biology
    Proceedings of the National Academy of Sciences
  • 2006
The evidence to date supports the hypothesis that, just like other opsin photopigments, the critical first event in melanopsin activation is photoisomerization of the retinaldehyde chromophore from a cis to an all-trans conformation.
...

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