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Concept

Photorécepteur (biologie)

Résumé

Suivant le contexte, le terme photorécepteur peut désigner :

un neurone sensoriel sensible à la lumière que l'on trouve sur la couche postérieure de la rétine (on parle alors de cellule photoréceptrice ou neurone photorécepteur) ;

la molécule qui assure la transduction de l'énergie lumineuse en signal biochimique au sein de la cellule photoréceptrice ;

une protéine photoréceptrice ou activée par certaines longueurs d'onde de la lumière, y compris chez les bactéries, champignons et les plantes ; ces dernières disposent de plusieurs types de photorécepteurs différents, dont les cryptochromes.

Les cryptochromes (présents chez de nombreux animaux et plantes) ne sont activés que par la lumière bleue ou bleue-verte du spectre visible, mais qui sont également sensible à un champ magnétique ou électromagnétique. Les observations faites sur une plante modèle (Arabidopsis thaliana), laissent penser que chez les plantes, les cryptochromes agissent synergiquement avec les phytochrome

Source officielle

https://fr.wikipedia.org/wiki/Photor%C3%A9cepteur_(biologie)

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Publications associées (34)

Mutations in the polyglutamylase geneTTLL5, expressed in photoreceptor cells and spermatozoa, are associated with cone-rod degeneration and reduced male fertility

Hereditary retinal degenerations encompass a group of genetic diseases characterized by extreme clinical variability. Following next-generation sequencing and autozygome-based screening of patients presenting with a peculiar, recessive form of cone-dominated retinopathy, we identified five homozygous variants [p.(Asp594fs), p.(Gln117*), p.(Met712fs), p.(Ile756Phe), and p.(Glu543Lys)] in the polyglutamylase-encoding gene TTLL5, in eight patients from six families. The two male patients carrying truncating TTLL5 variants also displayed a substantial reduction in sperm motility and infertility, whereas those carrying missense changes were fertile. Defects in this polyglutamylase in humans have recently been associated with cone photoreceptor dystrophy, while mouse models carrying truncating mutations in the same gene also display reduced fertility in male animals. We examined the expression levels of TTLL5 in various human tissues and determined that this gene has multiple viable isoforms, being highly expressed in testis and retina. In addition, antibodies against TTLL5 stained the basal body of photoreceptor cells in rat and the centrosome of the spermatozoon flagellum in humans, suggesting a common mechanism of action in these two cell types. Taken together, our data indicate that mutations in TTLL5 delineate a novel, allele-specific syndrome causing defects in two as yet pathogenically unrelated functions, reproduction and vision.

Oxford University Press2016

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The majority of diseases in the retina are caused by genetic mutations affecting the development and function of photoreceptor cells. The transcriptional networks directing these processes are regulated by genes such as nuclear hormone receptors. The nuclear hormone receptor gene Rev-erb alpha/Nr1d1 has been widely studied for its role in the circadian cycle and cell metabolism, however its role in the retina is unknown. In order to understand the role of Rev-erb alpha/Nr1d1 in the retina, we evaluated the effects of loss of Nr1d1 to the developing retina and its co-regulation with the photoreceptor-specific nuclear receptor gene Nr2e3 in the developing and mature retina. Knock-down of Nr1d1 expression in the developing retina results in pan-retinal spotting and reduced retinal function by electroretinogram. Our studies show that NR1D1 protein is co-expressed with NR2E3 in the outer neuroblastic layer of the developing mouse retina. In the adult retina, NR1D1 is expressed in the ganglion cell layer and is co-expressed with NR2E3 in the outer nuclear layer, within rods and cones. Several genes co-targeted by NR2E3 and NR1D1 were identified that include: Nr2c1, Recoverin, Rgr, Rarres2, Pde8a, and Nupr1. We examined the cyclic expression of Nr1d1 and Nr2e3 over a twenty-four hour period and observed that both nuclear receptors cycle in a similar manner. Taken together, these studies reveal a novel role for Nr1d1, in conjunction with its cofactor Nr2e3, in regulating transcriptional networks critical for photoreceptor development and function.

Public Library of Science2011

Chargement

NR2E3 Mutations in Enhanced S-Cone Sensitivity Syndrome (ESCS), Goldmann-Favre Syndrome (GFS), Clumped Pigmentary Retinal Degeneration (CPRD), and Retinitis Pigmentosa (RP)

Pascal Escher

NR2E3, also called photoreceptor-specific nuclear receptor (PNR), is a transcription factor of the nuclear hormone receptor superfamily whose expression is uniquely restricted to photoreceptors. There, its physiological activity is essential for proper rod and cone photoreceptor development and maintenance. Thirty-two different mutations in NR2E3 have been identified in either homozygous or compound heterozygous state in the recessively inherited enhanced S,cone sensitivity syndrome (ESCS), Goldmann-Favre syndrome (GFS), and clumped pigmentary retinal degeneration (CPRD). The clinical phenotype common to all these patients is night blindness, rudimental or absent rod function, and hyperfunction of the "blue" S,cones. A single p.G56R mutation is inherited in a dominant manner and causes retinitis pigmentosa (RP). We have established a new locus-specific database for NR2E3 (www.LOVD.nl/eye), containing all reported mutations, polymorphisms, and unclassified sequence variants, including novel ones. A high proportion of mutations are located in the evolutionarily-conserved DNA-binding domains (DBDs) and ligand,binding domains (LBDs) of NR2E3. Based on homology modeling of these NR2E3 domains, we propose a structural localization of mutated residues. The high variability of clinical phenotypes observed in patients affected by NR2E3,linked retinal degenerations may be caused by different disease mechanisms, including absence of DNA-binding, altered interactions with transcriptional coregulators, and differential activity of modifier genes. Hum Murat 30:1475-1485, 2009. (C) 2009 Wiley-Liss, Inc.

2009

Chargement

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Personnes associées (4)

Diego Ghezzi, Sabine Süsstrunk, Pascal Escher, Paola Vagni

Unités associées (2)

Chaire Medtronic en Neuroingenierie

Laboratoire d'images et representation visuelle

Concepts associés (75)

Rétine

vignette|(Fig. 1) Rétinographie : la tache grise au centre est la macula, la tache claire est la papille. vignette|(Fig. 2) Organisation axiale simplifiée de la rétine. La figure montre le fond de l’œ

Cône (photorécepteur)

thumb|Cônes et bâtonnets de la rétine en microscopie électronique (fausses couleurs). Les cônes sont des photorécepteurs situés dans la rétine, transformant le signal électromagnétique de la lumière e

Vue

thumb|250px|Ommatidies de krill antarctique, composant un œil primitif adapté à une vision sous-marine. thumb|250px|Yeux de triops, primitifs et non mobiles. thumb|250px|Yeux multiples d'une araignée

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Cours associés (12)

BIO-369: Randomness and information in biological data

Biology is becoming more and more a data science, as illustrated by the explosion of available genome sequences. This course aims to show how we can make sense of such data and harness it in order to understand biological processes in a quantitative way.

BIO-311: Neuroscience

The course starts with fundamentals of electrical - and chemical signaling in neurons. Students then learn how neurons in the brain receive and process sensory information, and how other neurons control the behavior of an animal. Furthermore, memory, learning, and brain disorders will be introduced.

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The course covers the fundaments of bioelectronics and integrated microelectronics for biomedical and implantable systems. Issues and trade-offs at the circuit and systems levels of invasive microelectronic systems as well as their eluding designs, methods and classical implementations are discussed

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Séances de cours associées (20)

Séances de cours associées

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