An AKAP-Lbc-RhoA interaction inhibitor promotes the translocation of aquaporin-2 to the plasma membrane of renal collecting duct principal cells

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • A Kinase Anchor Proteins / metabolism*
  • Aquaporin 2 / metabolism*
  • Cell Membrane / drug effects
  • Cell Membrane / metabolism*
  • HEK293 Cells
  • Humans
  • Kidney Tubules, Collecting / cytology*
  • Minor Histocompatibility Antigens / metabolism*
  • Protein Binding / drug effects
  • Protein Transport / drug effects
  • Proto-Oncogene Proteins / metabolism*
  • Small Molecule Libraries / chemistry
  • Small Molecule Libraries / pharmacology*
  • Structure-Activity Relationship
  • rhoA GTP-Binding Protein / metabolism*


  • A Kinase Anchor Proteins
  • AKAP13 protein, human
  • Aquaporin 2
  • Minor Histocompatibility Antigens
  • Proto-Oncogene Proteins
  • Small Molecule Libraries
  • rhoA GTP-Binding Protein

Grant support

This work was supported by grants from the Else Kröner-Fresenius-Stiftung (2013_A145), the German-Israeli Foundation (G.I.F. I-1210-286.13/2012), the German Centre for Cardio-vascular Research (DZHK 81X210012 and B18-005 SE), the Deutsche Forschungsgemein-schaft (DFG KL1415/7-1) and the Bundesministerium für Bildung und Forschung (BMBF; 16GW0179K) to EK. The Screening Unit of the FMP is jointly co-financed by the Max-Delbrueck Centre, the Berlin Institute of Health and the Leibniz-Forschungsinstitut für Moleku-lare Pharmakologie.