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B. Reidel, A. Gießl, U. Wolfrum; Arrestin and Transducin Translocations Associated With the Dark Adaptation of Rod Photoreceptor Cells Are Fully Dependent on the Cytoskeleton . Invest. Ophthalmol. Vis. Sci. 2006;47(13):5528.
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Arrestin and the visual G–protein transducin move between the inner and outer segment of the photoreceptor cell in a light–dependent way. Their compartmented distribution under the diverse light conditions is assumed to participate in long term light adaptation. The transport mechanisms and their regulation underlying these intracellular movements still remained largely elusive. In the present study, we investigated the light–dependent movements of transducin and arrestin in organotypic retina culture and evaluated their dependency on actin filaments and the microtubule cytoskeleton.
Maturating mouse retinas were cultured and kept under cyclic light. Cultures were treated with cytoskeletal drugs, namely with cytochalasin D or thiabendazole. The cytoskeleton was analyzed by light and electron microscopy. Light–dependent movements of transducin and arrestin were visualized by immunocytochemistry.
Light–dependent movements of arrestin and transducin, described in vertebrate eyes were confirmed ex vivo in organotypic retina culture. Treatments with cytoskeletal drugs affected actin filaments and the microtubule system of photoreceptor cells. These treatments interfered with the translocation of arrestin and transducin from the outer segment to the inner segment or vice versa, respectively, during dark adaptation of photoreceptors. Furthermore, the translocation of arrestin was slowed during light adaptation after microtubule destabilization by thiabendazole treatments
The physiological conditions of the organotypic retina culture are suitable for analysis of light–dependent molecular translocations in vertebrate photoreceptor cells. Our present study revealed that during dark adaptation, the translocation of arrestin and transducin is dependent on actin filaments as well as on the microtubule system of photoreceptor cells. In contrast, the molecular movements associated with the light adaptation are not fully dependent on both cytoskeletal systems. Our data strengthen the hypothesis that different mechanisms are responsible for the oppositional translocation of arrestin and transducin under different light conditions.
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