cAMP-Dependent Regulation of the Phototransduction Cascade in Cones
cAMP-Dependent Regulation of the Phototransduction Cascade in Cones
复制标题
视锥细胞中光转导级联的 cAMP 依赖性调节
DOI：
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
M. Firsov
中科院分区：
文献类型：
--
作者：
V. S. Sitnikova;L. Astakhova;M. Firsov
由于复杂的调节机制，视网膜光感受器-视锥和视杆-能够在广泛的光照水平上进行光适应。其中，研究最多的是钙反馈电路，它可以解释大约50%的实际光敏度调节。还有其他的调节机制也能够根据光照水平来调节感光细胞的光反应，特别是通过昼夜节律调节光转导级联反应。在昼夜周期的暗期，光感受器内cAMP水平升高，视杆敏感度增加，这可被认为是一种适应行为。在视锥的情况下，它在高照度下工作，在黄昏条件下对视觉几乎没有贡献，暗阶段敏感度的增加可能没有适应价值。我们在这里报道了我们的研究，即[cAMP]in的变化如何影响鲤鱼球果中光转导级联的操作。[cAMP]in的增加是通过与腺苷环化酶激活剂Forsklin孵育细胞而获得的。福斯可林被发现可以减缓锥体中光反应的两个阶段--上升阶段和下降阶段。因此，与杆状细胞相比，锥状细胞对Forsklin的光敏感度没有反应，但暗电流几乎减少了两倍。因此，锥形光导级联反应对[cAMP]In增加的反应与杆状反应明显不同。锥体内[cAMP]in的这种效应也可能具有适应价值--不是以增加敏感性的形式，而是以减少在黑暗阶段不起作用的细胞的代谢负荷的形式。
Retinal photoreceptors – cones and rods – are able to undergo light adaptation over a wide range of illumination levels due to a complex of regulatory mechanisms. Among these, the best studied are calcium feedback circuits, which can explain about 50% of the actual regulation of light sensitivity. There are other regulatory mechanisms also able to adjust photoreceptor light responses depending on the illumination level, in particular regulation of the phototransduction cascade through the diurnal rhythm. During the dark phase of the diurnal cycle, cAMP levels in photoreceptors increase and rod sensitivity increases, which can be regarded as an adaptive action. In the case of cones, which operate at high illumination levels and make virtually no contribution to vision in twilight conditions, the increase in sensitivity in the dark phase may not have adaptive value. We report here our studies of how changes in [cAMP] in affect the operation of the phototransduction cascade in carp cones. Increases in [cAMP] in were obtained by incubating cells with the adenylate cyclase activator forskolin. Forskolin was found to slow both phases – the rise phase and the descending phase – of the light response in cones. As a result, cones, in contrast to rods, did not respond to forskolin with increases in light sensitivity but showed an almost two-fold reduction in the dark current. Thus, the reaction of the cone phototransduction cascade to increases in [cAMP] in was significantly different from the reaction in rods. This effect of [cAMP] in in cones may also have adaptive value – not in the form of increased sensitivity but as a reduction in the metabolic load on cells not functioning in the dark phase.
在营养不良性视网膜变性慢速 (rds) 小鼠的光感受器中，光和多巴胺受体对 cAMP 的调节功能失调。
影响因子：
3.4
作者：
Nir,I;Haque,R;Iuvone,PM
通讯作者：
Iuvone,PM
影响因子：
5.5
作者：
LAMB, TD;PUGH, EN
通讯作者：
PUGH, EN