Light adaptation in vertebrate photoreceptors is mediated by multiple mechanisms, one of which could involve nuclear feedback and changes in gene expression. Therefore, we have investigated light adaptation-associated changes in gene expression using microarrays and real-time PCR in isolated photoreceptors, in cultured isolated retinas and in acutely isolated retinas. In all three preparations after 2 h of an exposure to a bright light, we observed an up-regulation of almost 100% of three genes, Sag, Guca1a and Guca1b, coding for proteins known to play a major role in phototransduction: arrestin, GCAP1 and GCAP2. No detectable up-regulation occurred for light exposures of less than 1 h. Functional in vivo electroretinographic tests show that a partial recovery of the dark current occurred 1-2 h after prolonged illumination with a steady light that initially caused a substantial suppression of the photoresponse. These observations demonstrate that prolonged illumination results in the up-regulation of genes coding for proteins involved in the phototransduction signalling cascade, possibly underlying a novel component of light adaptation occurring 1-2 h after the onset of a steady bright light.
|Autori:||CODEGA P; DELLA SANTINA L; GARGINI M; BEDOLLA DE; SUBKHANKULOVA T; LIVESEY FJ; CERVETTO L;TORRE V|
|Titolo:||Prolonged illumination up-regulates arrestin and two GCAPs: a novel mechanism for light adaptation|
|Anno del prodotto:||2009|
|Digital Object Identifier (DOI):||10.1113/jphysiol.2009.168609|
|Appare nelle tipologie:||1.1 Articolo in rivista|