Nedvetsky Pavel I, Stefan Eduard, Frische Sebastian, Santamaria Katja, Wiesner Burkhard, Valenti Giovanna, Hammer John A, Nielsen Søren, Goldenring James R, Rosenthal Walter, Klussmann Enno
Leibniz-Institut für Molekulare Pharmakologie (FMP), Campus Berlin-Buch, 13125 Berlin, Germany.
Traffic. 2007 Feb;8(2):110-23. doi: 10.1111/j.1600-0854.2006.00508.x. Epub 2006 Dec 6.
Arginine-vasopressin (AVP) regulates water reabsorption in renal collecting duct principal cells. Its binding to Gs-coupled vasopressin V2 receptors increases cyclic AMP (cAMP) and subsequently elicits the redistribution of the water channel aquaporin-2 (AQP2) from intracellular vesicles into the plasma membrane (AQP2 shuttle), thereby facilitating water reabsorption from primary urine. The AQP2 shuttle is a paradigm for cAMP-dependent exocytic processes. Using sections of rat kidney, the AQP2-expressing cell line CD8, and primary principal cells, we studied the role of the motor protein myosin Vb, its vesicular receptor Rab11, and the myosin Vb- and Rab11-binding protein Rab11-FIP2 in the AQP2 shuttle. Myosin Vb colocalized with AQP2 intracellularly in resting and at the plasma membrane in AVP-treated cells. Rab11 was found on AQP2-bearing vesicles. A dominant-negative myosin Vb tail construct and Rab11-FIP2 lacking the C2 domain (Rab11-FIP2-DeltaC2), which disrupt recycling, caused condensation of AQP2 in a Rab11-positive compartment and abolished the AQP2 shuttle. This effect was dependent on binding of myosin Vb tail and Rab11-FIP2-DeltaC2 to Rab11. In summary, we identified myosin Vb as a motor protein involved in AQP2 recycling and show that myosin Vb- and Rab11-FIP2-dependent recycling of AQP2 is an integral part of the AQP2 shuttle.
精氨酸加压素（AVP）调节肾集合管主细胞中的水重吸收。它与Gs偶联的加压素V2受体结合会增加环磷酸腺苷（cAMP），随后引发水通道蛋白2（AQP2）从细胞内囊泡重新分布到质膜（AQP2穿梭），从而促进原尿中的水重吸收。AQP2穿梭是cAMP依赖性胞吐过程的一个范例。我们使用大鼠肾脏切片、表达AQP2的细胞系CD8和原代主细胞，研究了运动蛋白肌球蛋白Vb、其囊泡受体Rab11以及肌球蛋白Vb和Rab11结合蛋白Rab11-FIP2在AQP2穿梭中的作用。在静息状态下，肌球蛋白Vb与细胞内的AQP2共定位，在AVP处理的细胞中则与质膜共定位。在携带AQP2的囊泡上发现了Rab11。一种显性负性肌球蛋白Vb尾部构建体和缺乏C2结构域的Rab11-FIP2（Rab11-FIP2-DeltaC2），它们会破坏循环，导致AQP2在Rab11阳性区室中聚集，并消除AQP2穿梭。这种效应依赖于肌球蛋白Vb尾部和Rab11-FIP2-DeltaC2与Rab11的结合。总之，我们确定肌球蛋白Vb是参与AQP2循环的运动蛋白，并表明肌球蛋白Vb和Rab11-FIP2依赖性的AQP2循环是AQP2穿梭的一个组成部分。
