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Kidney Week

Abstract: PO1207

Protein 4.1O Links Polycystin 1 to the Actin Cytoskeleton and Modulates Hippo Signaling

Session Information

Category: Genetic Diseases of the Kidneys

  • 1001 Genetic Diseases of the Kidneys: Cystic


  • Vienken, Theresia, Heinrich-Heine-Universitat Dusseldorf, Dusseldorf, Nordrhein-Westfalen, Germany
  • Koenigshausen, Eva, Heinrich-Heine-Universitat Dusseldorf, Dusseldorf, Nordrhein-Westfalen, Germany
  • Rump, Lars C., Heinrich-Heine-Universitat Dusseldorf, Dusseldorf, Nordrhein-Westfalen, Germany
  • Sellin, Lorenz, Heinrich-Heine-Universitat Dusseldorf, Dusseldorf, Nordrhein-Westfalen, Germany

The majority of ADPKD patients have a PKD1 gene mutation. PKD1 codes for Polycystin-1 (PC-1). Cyst formation is caused by altered renal tubular cell proliferation. Protein 4.1 family members are actin adaptors, which link plasma membrane receptors to the actin cytoskeleton. Protein 4.1O (FRMD3) is a candidate gene for diabetic nephropathy. Furthermore, protein 4.1O has properties of a tumor suppressor. This study investigates the molecular and cellular properties of protein 4.1O as a potential ADPKD modifier and therapeutic target.


PC-1 full-length and truncation mutants were transiently expressed. PC-1 interaction with protein 4.1O and its truncation mutants were investigated. Truncation mutants cover the N- and C-terminal domains of protein 4.1O (Band 4.1, FERM, actin-binding domain and coiled coil domain). Coimmunoprecipitations of protein 4.1O with PC-1 in IMCD cell lysates were done. Pulldown experiments with bacterial recombinant protein 4.1O and F-actin were performed. The modulation of the PC-1 signaling properties by protein 4.1O were investigated in luciferase assays for c-myc and TEAD. FRMD3 core promotor regions were cloned into luciferase reporter.


Coimmunoprecipitations show an interaction of protein 4.1O to PC-1 full-length. The C-terminus of PC-1 interacts with four isoforms of protein 4.1O (201, 202, 204, 207). The truncation mapping and isoform alignment identfies a potential leucine zipper domain in protein 4.1O as the C-terminal binding domain to PC-1. The N-terminal protein 4.1O FERM domain is also sufficient to mediate PC-1 interaction.
Protein 4.1O C-terminus binds to F-actin and links the PC-1 C-terminus to the cytoskeleton. Protein 4.1O silences the PC-1 mediated transactivation of c-myc and hippo signaling (TEAD). Furthermore, F-actin destabilization influences the PC-1 induced hippo signaling. PC-1 activates the protein 4.1O promotor.


Both, the FERM domain and leucine zipper containing coiled coil domain of protein 4.1O interact with the PC-1 C-terminus. The interaction of protein 4.1O links PC-1 to the actin cytoskeleton. The protein 4.1O interaction inhibits the PC-1 mediated activation of c-myc and hippo signaling. Furthermore, protein 4.1O provides a F-actin based sensitivity to the PC-1 mediated hippo signaling. In summary, protein 4.1O shows features of an anti-cystogenic protein.