Purchase this article with an account.
Zhijing Zhang, Xiaoqin Liu, Hongyan Li, John O'Brien, Christophe Ribelayga; Circadian Clock Control of Connexin 36 Phosphorylation in Mouse Retinal Photoreceptors. Invest. Ophthalmol. Vis. Sci. 2011;52(14):5282.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Recent work has demonstrated that cone photoreceptors are coupled to each other and to rod photoreceptors through gap junctions made of connexin 36 (Cx36) and that photoreceptor coupling is modulated by a circadian (24-h) clock in the retina, so that coupling is weak during the day and strong at night. Using recently developed phospho-specific antibodies against the two primary regulatory phosphorylation sites of Cx36: S110 and S293, we tested whether a circadian clock controls the phosphorylation state of Cx36 in mouse retina photoreceptors.
CBA/CaJ mice were sacrificed under infrared illumination during the subjective day or subjective night or under room lights during the day. Eyes were fixed in 1% carbodiimide in PBS for 30 minutes at room temperature. A classical immunohistochemistry procedure was used to react retinal sections with a mixture of antibodies containing one of the two phospho-specific rabbit polyclonal anti-Cx36 antibodies (anti-phospho-S110 and anti-phospho-S293) and a mouse monoclonal antibody to Cx36 (anti-Cx35/36; Millipore). Secondary antibodies were conjugated to fluorescent dyes and signals were observed and photographed with confocal microscopy.
Cx36 immunoreactivity was detected in the OPL in each of the different experimental conditions. Although the number of Cx36 plaques did not change between subjective day and subjective night and light-adapted condition during the day, the phosphorylation state of Cx36 was different between the conditions. Specifically, Cx36 phosphorylation was low during the subjective day and during the day under light-adapted condition, but much higher during the subjective night.
The data demonstrate that a circadian clock controls the phosphorylation state of Cx36 and not the number of Cx36-containing gap junctions in photoreceptor cells. Thus, our work strongly suggests that the nighttime state, which is characterized by extensive photoreceptor coupling, results from the circadian clock-induced phosphorylation of Cx36.
This PDF is available to Subscribers Only