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Abstract: FR-PO708

The Redundant and Unique Interactors of YAP and TAZ in Podocyte Homeostasis and Disease

Session Information

Category: Glomerular Diseases

  • 1304 Glomerular Diseases: Podocyte Biology

Authors

  • Ester, Lioba, Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
  • Cabrita, Inês, Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
  • Ventzke, Michel Tim, Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
  • Benzing, Thomas, Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
  • Habbig, Sandra, Paediatric Nephrology, Children's University Hospital Cologne, Faculty of Medicine, University of Cologne, Cologne, Germany
  • Schermer, Bernhard, Department II of Internal Medicine and Center for Molecular Medicine Cologne, University of Cologne, Faculty of Medicine and University Hospital Cologne, Cologne, Germany
Background

The two effector proteins of the Hippo signaling pathway, YAP and TAZ, play a pivotal role in the cellular homeostasis of podocytes and the pathogenesis of focal segmental glomerulosclerosis (FSGS). The two proteins share 46% amino acid identity and are often regarded as homolog proteins. However, the podocyte-specific knockout of TAZ results in milder proteinuria and FSGS than the podocyte-specific YAP knockout. We aim to unravel the unique and redundant functions of YAP and TAZ in podocytes by identifying podocyte-specific interactors in health and disease.

Methods


We used immortalized podocytes (hsMPs) and co-immunoprecipitated YAP or TAZ with specific antibodies. To overcome drawbacks resulting from these two proteins’ homology, we generated hsMPs expressing FLAG-tagged YAP or TAZ using TALEN-based genome editing. For in vivo purposes, we generated transgenic mice expressing 3xFLAG.YAP and TAZ.3xFLAG using CRISPR/Cas9. YAP or TAZ were pulled down in vitro from podocytes and in vivo from isolated glomeruli, followed by mass spectrometry analysis. Further, we generated YAP or TAZ podocyte-specific knockout mice as well as double knockouts, to shed light on common, distinct, and possible compensatory roles of YAP and TAZ in podocyte disease.

Results


Within the interactome analyses of the hsMPs, we identified shared and non-shared interacting proteins between YAP and TAZ. Of all interactors, 60% overlapped for both, while 40% were unique. These results comprise known and novel interactors, including Fat1, Actn4, or Neph1. Interactome analysis of the nuclear fraction identified specifically nuclear interactors of YAP and TAZ, including known transcription factors (e.g. TEADs) and also ~30% of new nuclear interacting proteins. Currently, we are investigating the mechanistic role of novel candidates in FSGS while we are working on the in vivo models.

Conclusion


YAP and TAZ are critical proteins in the podocyte’s homeostasis with divergent functions and interactors. Overlapping and distinct candidates identified in interactome analyses conducted both in in vitro and in vivo systems suggest both shared and unique podocyte-specific functions. These novel unique and shared interactors of YAP and TAZ in podocytes will help to understand the specific impact of YAP and TAZ in the development of FSGS and recovery from podocyte injury.