Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

PURPOSE: Gap junctional coupling between rod and cone photoreceptor cells is regulated by light and the circadian clock, and contributes to retinal light adaptation. Phosphorylation of connexin 36 (Cx36) has been proposed as the mechanism involved. We investigated whether retinal Cx36 is also regulated at the level of transcript and protein expression. METHODS: At specific time points in a diurnal or circadian cycle, Cx36 protein was assessed by Western blotting and immunohistochemistry, and Cx36 transcript by quantitative real time PCR in a melatonin-deficient (C57BL6/FVB) and two melatonin-proficient (C3H(+/+) and C3H(rd/rd)) mouse strains. RESULTS: In C57BL6/FVB mice during a diurnal cycle, Cx36 protein expression was rhythmic, peaking at approximately zeitgeber time (ZT) 20. However, this rhythm was not maintained in the circadian cycle. In C3H(+/+) mice levels of Cx36 protein were higher at night and subjective night relative to day and subjective day, respectively. These patterns of Cx36 expression were localized primarily to the outer plexiform layer in both strains. Cx36 transcript expression was higher at night and subjective night relative to day and subjective day in C57BL6/FVB and C3H(+/+) mice. Rhythmic expression of Cx36 transcript was lost in retinally degenerate C3H(rd/rd) mice. CONCLUSIONS: The results suggested the circadian control of Cx36 protein expression is dependent on melatonin, whereas the circadian regulation of Cx36 transcript expression may be controlled directly by the circadian clock. In addition to post-translational modification, regulation of Cx36 transcript and protein expression may be important during retinal light adaptation.

Original publication




Journal article


Invest Ophthalmol Vis Sci

Publication Date





821 - 829


Animals, Blotting, Western, Circadian Clocks, Circadian Rhythm, Connexins, Female, Gene Expression Regulation, Immunohistochemistry, Male, Melatonin, Mice, Mice, Inbred C3H, Mice, Inbred C57BL, Mice, Mutant Strains, RNA, Messenger, Real-Time Polymerase Chain Reaction, Retina