ASN's Mission

ASN leads the fight to prevent, treat, and cure kidney diseases throughout the world by educating health professionals and scientists, advancing research and innovation, communicating new knowledge, and advocating for the highest quality care for patients.

learn more

Contact ASN

1401 H St, NW, Ste 900, Washington, DC 20005

email@asn-online.org

202-640-4660

The Latest on Twitter

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

Authors

  • 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
Background

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.

Methods

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.

Results

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.

Conclusion

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.