Functional expression of connexin57 in horizontal cells of the mouse retina
Functional expression of connexin57 in horizontal cells of the mouse retina
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DOI：
10.1111/j.0953-816x.2004.03360.x
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发表时间：
2004-05-01
影响因子：
3.4
通讯作者：
Willecke, K
中科院分区：
文献类型：
--
作者：
Hombach, S;Janssen-Bienhold, U;Willecke, K
水平细胞是脊椎动物视网膜的中间神经元，表现出强烈的电和示踪剂耦合，但通道形成连接蛋白的身份仍然难以捉摸。在这里，我们表明，小鼠视网膜水平细胞表达连接蛋白57（Cx57）。我们已经产生了Cx57缺陷型小鼠Cx57的编码区与lacZ报告基因，内源性Cx57启动子的控制下表达的取代。这些小鼠具有生育能力，没有表现出明显的解剖学或行为异常。Cx57 mRNA在野生型同窝仔的视网膜中表达，但在Cx57缺陷小鼠的视网膜中不存在。先前报道的结果，Cx57基因在其他几个小鼠组织中表达非常弱，结果证明是非特异性的。Cx57 mRNA在成年小鼠的视网膜中大量表达，而在胸腺中表达较弱，但在所有其他成年组织（包括脑）中均不表达。此外，Cx57在受孕后E16.5至E18.5天在胚胎肾中表达，如lacZ表达模式所示。在视网膜内，lacZ信号被专门分配到水平细胞的基础上与细胞类型特异性标记蛋白的共定位。显微注射神经生物素到离体视网膜的水平细胞中，发现与野生型对照相比，Cx57缺陷视网膜中的示踪剂偶联不到1%。Cx57是第一个在哺乳动物水平细胞中鉴定的连接蛋白，并且是第一个其表达明显仅限于一种类型的神经元的连接蛋白。
Horizontal cells are interneurons of the vertebrate retina that exhibit strong electrical and tracer coupling but the identity of the channel-forming connexins has remained elusive. Here we show that horizontal cells of the mouse retina express connexin57 (Cx57). We have generated Cx57-deficient mice by replacing the Cx57 coding region with a lacZ reporter gene, expressed under control of the endogenous Cx57 promoter. These mice were fertile and showed no obvious anatomical or behavioural abnormalities. Cx57 mRNA was expressed in the retina of wild-type littermates but was absent from the retina of Cx57-deficient mice. Previously reported results that the Cx57 gene was very weakly expressed in several other mouse tissues turned out to be unspecific. Cx57 mRNA is abundantly expressed in the retina and weakly in the thymus of adult mice but absent in all other adult tissues tested, including brain. Furthermore, Cx57 is expressed in embryonic kidney at E16.5 to E18.5 days post-conception, as indicated by the pattern of lacZ expression. Within the retina, lacZ signals were assigned exclusively to horizontal cells based on co-localization with cell-type-specific marker proteins. Microinjection of Neurobiotin into horizontal cells of isolated retinae revealed less than 1% of tracer coupling in Cx57-deficient retinae compared with wild-type controls. Cx57 is the first connexin identified in mammalian horizontal cells and the first connexin whose expression is apparently restricted to only one type of neuron.