Abstract: SA-OR002

Deep Mapping of the Podocyte Proteome Unravels Altered Protein Dynamics during Differentiation

Session Information

  • A View on the Glomerulus
    November 04, 2017 | Location: Room 294, Morial Convention Center
    Abstract Time: 04:42 PM - 04:54 PM

Category: Glomerular

  • 1003 Glomerular: Cell Biology

Authors

  • Schroeter, Christina Barbara, University Hospital Cologne, Cologne, Germany
  • Benzing, Thomas, University of Cologne, Köln, Germany
  • Rinschen, Markus M., CECAD, Cologne, Germany
  • Brinkkoetter, Paul T., University Hospital Cologne, Cologne, Germany
Background

Podocytes are epithelial postmitotic cells which maintain the renal filtration barrier. Immortalized podocyte cell lines are widely utilized tools to estimate podocyte injury and cytoskeletal rearrangement processes in vitro. We intended to generate a comprehensive map of proteins expressed in proliferating and differentiated cultured human podocytes in vitro thereby providing a thorough database and useful tool for researchers in the podocyte field.

Methods

We analysed 7637 proteins in depth and quantified 7230 of them. We performed additional in-depth analyses of the cultured human podocyte proteome in order to characterize changes regarding protein expression, protein synthesis and proteostatic mechanisms during differentiation of the cells. We included a detailed analysis on the expression of podocyte-specific proteins that govern the function and dysfunction of the slit diaphragm, and of gene products mutated in hereditary nephrotic syndrome. Finally, we compared the resulting proteomic dataset to data obtained from the previously published murine cultured podocyte proteome. We also performed comparative analysis with transcriptomic data from cultured human podocytes.

Results

Cultured podocytes express abundant copy numbers of endogenous receptors. Some protein classes associated with podocyte disease, such as slit-diaphragm associated proteins and ion channels, were hardly detected. Differentiation-induced changes were comparable in mouse and human podocytes, but slight differences, e.g. in proteins associated with lipid metabolism were detected. Also, there were distinct differences in expression of genes commonly thought to be associated with podocyte function. Notably, this data set detected general perturbations in proteostatic mechanisms as a dominant alteration during podocyte differentiation irrespectively of the species: Proteasome activity and kinetics were high in the undifferentiated state and lysosomal activity was high in the differentiated state.

Conclusion

In conclusion, podocyte differentiation in vitro is largely associated with a proteostatic shift, and the deep proteomic mapping approach utilized here may demonstrate the limitations, but also the potential of podocyte cell culture.