Addition of human melanopsin renders mammalian cells photoresponsive

  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},
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.



Melanopsin forms a functional short-wavelength photopigment.

The experiments constitute the first direct demonstration that melanopsin forms a photopigment capable of activating a G-protein, but its spectral properties are not consistent with the action spectrum for circadian entrainment.

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.

Illumination of the Melanopsin Signaling Pathway

It is found that expression of melanopsin in Xenopus oocytes results in light-dependent activation of membrane currents through the Gαq/Gα11 G protein pathway, with an action spectrum closely matching that of melanpsin-expressing ipRGCs and of behavioral responses to light in mice lacking rods and cones.

Melanopsin-Containing Retinal Ganglion Cells: Architecture, Projections, and Intrinsic Photosensitivity

It is shown that melanopsin is present in cell bodies, dendrites, and proximal axonal segments of a subset of rat RGCs, most likely the visual pigment of phototransducing R GCs that set the circadian clock and initiate other non–image-forming visual functions.

Melanopsin and rod–cone photoreceptive systems account for all major accessory visual functions in mice

The rod–cone and melanopsin systems together seem to provide all of the photic input for these accessory visual functions such as pupillary light reflex and circadian photo-entrainment.

Melanopsin Is Required for Non-Image-Forming Photic Responses in Blind Mice

It is observed that mice with both outer-retinal degeneration and a deficiency in melanopsin exhibited complete loss of photoentrainment of the circadian oscillator, pupillary light responses, photic suppression of arylalkylamine-N-acetyltransferase transcript, and acute suppression of locomotor activity by light, indicating the importance of both nonvisual and classical visual photoreceptor systems for nonvisual photic responses in mammals.

The Photopigment Melanopsin Is Exclusively Present in Pituitary Adenylate Cyclase-Activating Polypeptide-Containing Retinal Ganglion Cells of the Retinohypothalamic Tract

Cloned rat melanopsin photopigment cDNA is cloned and in situ hybridization histochemistry combined with immunohistochemistry and colocalization studies reveal that melanops in was found exclusively in the PACAP-containing retinal ganglion cells located at the surface of somata and dendrites.

Diminished Pupillary Light Reflex at High Irradiances in Melanopsin-Knockout Mice

It is reported that in mice with the melanopsin gene ablated, RGCs retrograde-labeled from the suprachiasmatic nuclei were no longer intrinsically photosensitive, although their number, morphology, and projections were unchanged.

Zebrafish melanopsin: isolation, tissue localisation and phylogenetic position.

Melanopsin: An opsin in melanophores, brain, and eye.

Melanopsin mRNA is expressed in hypothalamic sites thought to contain deep brain photoreceptors and in the iris, a structure known to be directly photosensitive in amphibians, and expression in retinal and nonretinal tissues suggests a role in vision and nonvisual photoreceptive tasks.