Abstract：
The RS1 gene on Xp 22.13 encodes retinoschisin which is known to directly interact with the retinal Na/K-ATPase at the photoreceptor inner segments. Pathologic mutations in RS1 cause X-linked juvenile retinoschisis (XLRS), a hereditary retinal dystrophy in young males. To further delineate the retinoschisin-Na/K-ATPase complex, co-immunoprecipitation was performed with porcine and murine retinal lysates targeting the ATP1A3 subunit. This identified the voltage-gated potassium (Kv) channel subunits Kv2.1 and Kv8.2 as direct interaction partners of the retinal Na/K-ATPase. Colocalization of the individual components of the complex was demonstrated at the membrane of photoreceptor inner segments. We further show that retinoschisin-deficiency, a frequent consequence of molecular pathology in XLRS, causes mislocalization of the macromolecular complex during postnatal retinal development with a simultaneous reduction of Kv2.1 and Kv8.2 protein expression, while the level of retinal Na/K-ATPase expression remains unaffected. Patch-clamp analysis revealed no effect of retinoschisin-deficiency on Kv channel mediated potassium ion currents in vitro. Together, our data suggest that Kv2.1 and Kv8.2 together with retinoschisin and the retinal Na/K-ATPase are integral parts of a macromolecular complex at the photoreceptor inner segments. Defective compartmentalization of this complex due to retinoschisin-deficiency may be a crucial step in initial XLRS pathogenesis.
摘要：
Xp22.13上的RS1基因编码视网膜裂素，已知其与光感受器内段的视网膜Na/K-ATPase直接相互作用。RS1的病理突变导致X连锁的幼年视网膜裂（XLRS），年轻男性的遗传性视网膜营养不良。为了进一步描述视网膜裂素-Na/K-ATP酶复合物，用靶向ATP1A3亚基的猪和鼠视网膜裂解物进行共免疫沉淀。这将电压门控钾（Kv）通道亚基Kv2.1和Kv8.2鉴定为视网膜Na/K-ATPase的直接相互作用伙伴。在光感受器内节段的膜上证明了复合物的各个组分的共定位。我们进一步表明，视网膜分裂素缺乏，XLRS分子病理学的常见结果，在出生后视网膜发育过程中导致大分子复合物的错位，同时降低Kv2.1和Kv8.2蛋白表达，而视网膜Na/K-ATP酶表达水平未受影响。膜片钳分析显示，视网膜分裂素缺乏对体外Kv通道介导的钾离子电流没有影响。一起,我们的数据表明,Kv2.1和Kv8.2与视网膜裂素和视网膜Na/K-ATP酶一起是感光细胞内节段大分子复合物的组成部分.由于视网膜分裂素缺乏，这种复合物的区隔缺陷可能是XLRS最初发病机制的关键步骤。
