Light Activation of the Phosphoinositide Cycle in Intrinsically Photosensitive Chicken Retinal Ganglion Cells

Contín, María Ana; Verra, Daniela M.; Salvador, Gabriela Alejandra; Ilincheta, M. G.; Giusto, Norma M.; Guido, Mario E.

doi:10.1167/iovs.10-5643

Cited by 29 publications

(57 citation statements)

References 62 publications

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“…Conversely, when the light is on, cones and rods become hyperpolarized, stopping the release of glutamate and thus preventing the depolarization and subsequent HC response. In addition to their typical role in the retinal circuits, in nonmammalian vertebrates HCs may conserve vestiges of ancient photoreceptor cells (Scheme 1, scenario 2) as clearly demonstrated for ipRGCs (2,6,17,18). In teleosts, it has been reported that retinal HCs expressing VA opsin or OPN4 can intrinsically respond to light (28,29).…”

Section: Discussionmentioning

confidence: 93%

“…and TRP channel activation (18,(39)(40)(41). The embryological origin of these cells within the retina and other molecular features strongly suggest that ipRGCs and HCs are likely to derive from a common ancient photoreceptor cell.…”

Section: Discussionmentioning

confidence: 99%

“…In teleosts, it has been reported that retinal HCs expressing VA opsin or OPN4 can intrinsically respond to light (28,29). OPN4 is found in brain, iris, and retinal cells of vertebrates (1,3,5,6,12,(17)(18)(19) and highly conserved through evolution (38). In mammals OPN4 is confined to ipRGCs; however, the distribution of multiple Opn4s (Opn4m and Opn4x) in diverse retinal cell types of nonmammalian vertebrates suggests a biological function of higher complexity (see review in ref.…”

Section: Discussionmentioning

confidence: 99%

“…Evidence suggests that during the course of evolution, mammals lost some visual opsins and Opn4x as they entered the nocturnal niche. In the chicken retina, different laboratories have reported the expression of Opn4 genes in outer nuclear, inner nuclear, and ganglion cell layer (GCL) cells (12)(13)(14)(15)(16)(17)(18)(19)(20)(21). At the protein level, OPN4M was shown to be restricted to ipRGCs, whereas OPN4X was found in the GCL at embryo day 8 (E8) but mostly in PROX1 (+) horizontal cells (HCs) by E15 (21); the homeobox gene PROX1 is a universal HC marker that is expressed from E8 forward (22,23).…”

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Horizontal cells expressing melanopsin x are novel photoreceptors in the avian inner retina

Morera

Díaz

Guido

2016

Proc. Natl. Acad. Sci. U.S.A.

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In the vertebrate retina, three types of photoreceptors-visual photoreceptor cones and rods and the intrinsically photosensitive retinal ganglion cells (ipRGCs)-converged through evolution to detect light and regulate image-and nonimage-forming activities such as photic entrainment of circadian rhythms, pupillary light reflexes, etc. ipRGCs express the nonvisual photopigment melanopsin (OPN4), encoded by two genes: the Xenopus (Opn4x) and mammalian (Opn4m) orthologs. In the chicken retina, both OPN4 proteins are found in ipRGCs, and Opn4x is also present in retinal horizontal cells (HCs), which connect with visual photoreceptors. Here we investigate the intrinsic photosensitivity and functioning of HCs from primary cultures of embryonic retinas at day 15 by using calcium fluorescent fluo4 imaging, pharmacological inhibitory treatments, and Opn4x knockdown. Results show that HCs are avian photoreceptors with a retinal-based OPN4X photopigment conferring intrinsic photosensitivity. Light responses in HCs appear to be driven through an ancient type of phototransduction cascade similar to that in rhabdomeric photoreceptors involving a G-protein q, the activation of phospholipase C, calcium mobilization, and the release of the inhibitory neurotransmitter GABA. Based on their intrinsic photosensitivity, HCs may have a key dual function in the retina of vertebrates, potentially regulating nonvisual tasks together with their sister cells, ipRGCs, and with visual photoreceptors, modulating lateral interactions and retinal processing.retina | light responses | horizontal cell | phototransduction | melanopsin I n the vertebrate retina, photoreceptors can be classified according to their function as canonical or noncanonical. The first group comprises specialized ciliary retinal neurons, cones, and rods in the outer retina, which participate in the image-forming processes associated with day/night vision. The second group is composed of intrinsically photosensitive retinal ganglion cells (ipRGCs) in the inner retina, which preferentially participate in the processing of photic inputs related to nonimage-forming tasks (photic synchronization of circadian rhythms, pupillary light reflexes, inhibition of pineal melatonin, etc.) (1-7). The photopigment melanopsin (OPN4) (1) confers photosensitivity to ipRGCs as clearly shown through later experiments with OPN4 knockout mice or OPN4 heterologous expression in nonretinal cells for loss or gain of function, respectively (8-11). Through evolution, OPN4 appears to have been encoded by at least two genes in vertebrates: Opn4x and Opn4m, the Xenopus and mammalian ortholog genes, respectively (12). Interestingly, the first-appearing vertebrates, nonmammals including fish, amphibians, and birds, possess both Opn4 genes whereas mammals only have Opn4m. Evidence suggests that during the course of evolution, mammals lost some visual opsins and Opn4x as they entered the nocturnal niche. In the chicken retina, different laboratories have reported the expression of Opn4 genes in outer nuclear...

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Section: Discussionmentioning

confidence: 93%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Horizontal cells expressing melanopsin x are novel photoreceptors in the avian inner retina

Morera

Díaz

Guido

2016

Proc. Natl. Acad. Sci. U.S.A.

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“…Przykładowo, poziom mRNA mOpn4 jest wyższy w nocy i niższy w dzień, zaś mRNA RRH i RGR -wyższy w dzień, a niższy w nocy, co wskazuje na ich udział w synchronizacji rytmów biologicznych ze światłem otoczenia (5,16,22,38). Wszystkie wyżej wymienione fotoreceptory są wrażliwe na światło niebieskie, które odpowiada kolorowi nieba podczas czystego poranka i jest najlepszym sygnałem dla organizmu o przejściu nocy w dzień pozwalającym zsynchronizować biologię organizmu z zewnętrznymi warunkami oświetlenia (52,81 (1,20,22,40,49,53,62,65,79,86). Nie wiadomo jeszcze, z jakimi białkami G łączą się VA-opsyny, RGR oraz RRH.…”

Section: Artykuł Przeglądowy Reviewunclassified

Avian central clocking system

Prusik¹

2018

Medycyna Weterynaryjna

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W świecie roślin i zwierząt bardzo ważną rolę w funkcjonowaniu organizmu odgrywają rytmy biologiczne. Rytmy biologiczne są to cykliczne zjawiska naprzemiennego, okresowego nasilania się i hamowania procesów życiowych, np. występujących u zwierząt cyklów snu i czuwania, termoregulacji, pobierania pokarmu, ciśnienia krwi, oddychania, wylinki, pierzenia, nieśności (6, 14, 25-27, 29, 55, 56, 87). Częstotliwość cyklu różnych procesów biologicznych może się wahać od sekund przez minuty, dni, aż do miesięcy. Rytmy biologiczne mogą być endogenne -generowane przez wewnętrzny zegar biologiczny organizmu oraz egzogenne -generowane przez cyklicznie zmieniające się warunki środowiskowe (np. światło i ciemność, pory roku, wahania temperatury i wilgotności). U ptaków obiektem najczęstszych badań są obecnie rytmy dobowe (np. rytm aktywności lokomotorycznej, pobierania pokarmu, snu i czuwania, sekrecji melatoniny) oraz roczne -sezonowe (np. reprodukcji, migracji, hibernacji, pierzenia, śpiewu), generowane przez wewnętrzny zegar biologiczny, którego aktywność jest synchronizowana z zewnętrznymi warunkami oświetlenia (14,21,55,56,66). Cykliczne procesy życiowe synchronizowane ze światłem otoczenia nazywane są także procesami lub odpowiedziami chronobiologicznymi. Wewnętrzny zegar biologiczny składa się z trzech podstawowych elementów: sensorycznego systemu wejścia (tworzonego przez fotoreceptory), systemu genów zegarowych (oscylator) oraz efektorowego systemu wyjścia (reprezentowanego przez produkty genów odpowiedzialne za bezpośrednie efekty biologiczne) (55, 56). Oscylator jest "sercem" zegara biologicznego, generuje pojawienie się cyklicznie powtarzających się okresów na przemian podwyższonego i obniżonego poziomu różnych związków chemicznych, których rytm wydzielania jest "dopasowany" do określonej

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Melanopsin, the photopigment of intrinsically photosensitive retinal ganglion cells

Provencio

Warthen

2012

WIREs Membr Transp Signal

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Melanopsin (gene symbol : Opn4) is the G protein-coupled photopigment that confers photosensitivity upon intrinsically photosensitive retinal ganglion cells (ipRGCs). ipRGCs are the third class of retinal photoreceptor in mammals, complementing the two previously identified classes, the rods and cones. This novel class, however, differs from rods and cones in many significant ways. First, ipRGCs are more similar morphologically to other retinal ganglion cell classes than to other retinal photoreceptors, i.e., rods and cones. Instead of having photopigment concentrated in a specialized light-absorbing cellular domain such as the outer segment, ipRGCs have photopigment distributed throughout the plasma membrane of the cell. Second, the phototransduction cascade of ipRGCs more closely resembles that of the rhabdomeric photoreceptors that are typically found in the invertebrates rather than that of ciliary photoreceptors typical of vertebrate visual systems. Accordingly, like the rhabdomeric photoreceptors of invertebrates, ipRGCs depolarize in response to illumination while rods and cones hyperpolarize. Third, in addition to their inherent light sensitivity, ipRGCs also function as a conduit for information that originates in the rods and cones and is conveyed to the brain for the purposes of generating non-visual light responses.

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Light Activation of the Phosphoinositide Cycle in Intrinsically Photosensitive Chicken Retinal Ganglion Cells

Abstract: The results indicate for the first time that light stimulation of chicken RGC cultures activates the PIP cycle, causing an increase in intracellular levels of IP(3), changes in levels of phosphatidic acid, PIP, and PIP(2); and mobilization of Ca(2+).

Cited by 29 publications

References 62 publications

Horizontal cells expressing melanopsin x are novel photoreceptors in the avian inner retina

Horizontal cells expressing melanopsin x are novel photoreceptors in the avian inner retina

Avian central clocking system

Melanopsin, the photopigment of intrinsically photosensitive retinal ganglion cells

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