Melanopsin Triggers the Release of Internal Calcium Stores in Response to Light †

  title={Melanopsin Triggers the Release of Internal Calcium Stores in Response to Light †},
  author={Tida Kumbalasiri and Mark D. Rollag and Mauro C{\'e}sar Isoldi and A M Castrucci and Ignacio Provencio},
  journal={Photochemistry and Photobiology},
Melanopsin is the photopigment that confers photosensitivity upon intrinsically photosensitive retinal ganglion cells (ipRGCs). This subset of retinal ganglion cells comprises less than 2% of all RGCs in the mammalian retina. The paucity of melanopsin‐positive cells has made studies on melanopsin signaling difficult to pursue in ipRGCs. To address this issue, we have established several cell lines consisting of a transformed human embryonic kidney cell line (HEK293) stably expressing human… 

[Phototransduction mediated by melanopsin in intrinsically photosensitive retinal ganglion cells].

Melanopsin is the most recent photopigment described. As all the other opsins, it attaches in the retina as chromophore. Its amino acid sequence resembles more invertebrate opsins than those of

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.

Functional Expression, Targeting and Ca2+ Signaling of a Mouse Melanopsin‐eYFP Fusion Protein in a Retinal Pigment Epithelium Cell Line †

RPE‐derived cells expressing recombinant melanopsin may constitute a suitable system for the study of the structural and functional characteristics of melanopigment.

Light-Evoked Calcium Responses of Isolated Melanopsin-Expressing Retinal Ganglion Cells

Results indicate that Ca2+ influx through VGCCs, activated after action potential firing, was the primary source for light-evoked elevations in ipRGC [Ca2+]i.

Human melanopsin forms a pigment maximally sensitive to blue light (λmax ≈ 479 nm) supporting activation of Gq/11 and Gi/o signalling cascades

  • H. BailesR. Lucas
  • Biology
    Proceedings of the Royal Society B: Biological Sciences
  • 2013
The G-protein selectivity and spectral sensitivity of human melanopsin is similar to that previously described for rodents, supporting the utility of such laboratory animals for developing methods of manipulating this system using light or pharmacological agents.

Intrinsically photosensitive retinal ganglion cells.

The early work that provided the motivation for searching for a new mammalian photoreceptor, the ground-breaking discoveries, current progress that continues to reveal the unusual properties of these neuron photoreceptors, and directions for future investigation are reviewed.

The Intrinsic Blue Light Responses of Avian Müller Glial Cells Imply Calcium Release from Internal Stores

Non-neuronal cells in the vertebrate retina, Muller glial cells, express non-canonical photopigments and sense blue light causing calcium release from intracellular stores strongly suggesting a novel intrinsic photosensitivity and new regulatory events mediating light-driven processes with yet unknown physiological implications.

Intrinsically photosensitive retinal ganglion cells

ipRGCs are the primary retinal input to the hypothalamic suprachiasmatic nucleus (SCN), a circadian oscillator and biological clock, and this input entrains the SCN to the day/night cycle.

Melanopsin phototransduction: slowly emerging from the dark.

Melanosome transfer, photoreception and toxicity assays in melanophores

A new and powerful method for transfer experiments was developed and Amphibian immortalized melanophore cell line was used from the African claw frog, Xenopus laevis to study transfer of melanosomes to co-cultured fibroblasts.



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.

Addition of human melanopsin renders mammalian cells photoresponsive

It is shown that heterologous expression of human melanopsin in a mouse paraneuronal cell line (Neuro-2a) is sufficient to render these cells photoreceptive and that melanopigment functions as a bistable pigment in this system, having an intrinsic photoisomerase regeneration function that is chromatically shifted to longer wavelengths.

Rhabdomeric phototransduction initiated by the vertebrate photopigment melanopsin.

Molecular components of melanopsin signaling are reported using the cultured Xenopus dermal melanophore system to provide evidence of an invertebrate-like light-activated signaling cascade within vertebrate cells.

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.

Central projections of melanopsin‐expressing retinal ganglion cells in the mouse

Staining patterns after monocular enucleation revealed that the projections of these cells are overwhelmingly crossed except for the projection to the SCN, which is bilaterally symmetrical, and that other ganglion cells do contribute at least some retinal input to these targets.

HEK293S Cells Have Functional Retinoid Processing Machinery

Rhodopsin activation is measured by the early receptor current (ERC), a conformation-associated charge motion, in human embryonic kidney cells (HEK293S) expressing opsins. After rhodopsin bleaching