Schrade Katharina, Tröger Jessica, Eldahshan Adeeb, Zühlke Kerstin, Abdul Azeez Kamal R, Elkins Jonathan M, Neuenschwander Martin, Oder Andreas, Elkewedi Mohamed, Jaksch Sarah, Andrae Karsten, Li Jinliang, Fernandes Joao, Müller Paul Markus, Grunwald Stephan, Marino Stephen F, Vukićević Tanja, Eichhorst Jenny, Wiesner Burkhard, Weber Marcus, Kapiloff Michael, Rocks Oliver, Daumke Oliver, Wieland Thomas, Knapp Stefan, von Kries Jens Peter, Klussmann Enno
Max Delbrück Center for Molecular Medicine Berlin (MDC), Berlin, Germany.
Structural Genomics Consortium, University of Oxford, Oxford, United Kingdom.
PLoS One. 2018 Jan 26;13(1):e0191423. doi: 10.1371/journal.pone.0191423. eCollection 2018.
Stimulation of renal collecting duct principal cells with antidiuretic hormone (arginine-vasopressin, AVP) results in inhibition of the small GTPase RhoA and the enrichment of the water channel aquaporin-2 (AQP2) in the plasma membrane. The membrane insertion facilitates water reabsorption from primary urine and fine-tuning of body water homeostasis. Rho guanine nucleotide exchange factors (GEFs) interact with RhoA, catalyze the exchange of GDP for GTP and thereby activate the GTPase. However, GEFs involved in the control of AQP2 in renal principal cells are unknown. The A-kinase anchoring protein, AKAP-Lbc, possesses GEF activity, specifically activates RhoA, and is expressed in primary renal inner medullary collecting duct principal (IMCD) cells. Through screening of 18,431 small molecules and synthesis of a focused library around one of the hits, we identified an inhibitor of the interaction of AKAP-Lbc and RhoA. This molecule, Scaff10-8, bound to RhoA, inhibited the AKAP-Lbc-mediated RhoA activation but did not interfere with RhoA activation through other GEFs or activities of other members of the Rho family of small GTPases, Rac1 and Cdc42. Scaff10-8 promoted the redistribution of AQP2 from intracellular vesicles to the periphery of IMCD cells. Thus, our data demonstrate an involvement of AKAP-Lbc-mediated RhoA activation in the control of AQP2 trafficking.
用抗利尿激素（精氨酸血管加压素，AVP）刺激肾集合管主细胞会导致小GTP酶RhoA受到抑制，水通道蛋白2（AQP2）在质膜中富集。膜插入有助于从原尿中重吸收水分并微调体内水平衡。Rho鸟嘌呤核苷酸交换因子（GEFs）与RhoA相互作用，催化GDP与GTP的交换，从而激活GTP酶。然而，参与肾主细胞中AQP2调控的GEFs尚不清楚。A激酶锚定蛋白AKAP-Lbc具有GEF活性，特异性激活RhoA，并在原代肾内髓集合管主（IMCD）细胞中表达。通过筛选18431个小分子并围绕其中一个命中化合物合成一个聚焦文库，我们鉴定出一种AKAP-Lbc与RhoA相互作用的抑制剂。这种分子Scaff10-8与RhoA结合，抑制AKAP-Lbc介导的RhoA激活，但不干扰通过其他GEFs激活RhoA或小GTP酶Rho家族其他成员Rac1和Cdc42的活性。Scaff10-8促进AQP2从细胞内囊泡重新分布到IMCD细胞周边。因此，我们的数据表明AKAP-Lbc介导的RhoA激活参与了AQP2转运的调控。
