Abstract: SA-PO230

Studying the Role of Tcf21 In Vitro and In Vivo

Session Information

  • Glomerular: Cell Biology
    November 04, 2017 | Location: Hall H, Morial Convention Center
    Abstract Time: 10:00 AM - 10:00 AM

Category: Glomerular

  • 1003 Glomerular: Cell Biology

Authors

  • Kliewe, Felix, University Medicine Greifswald, Greifswald, Germany
  • Kuß, Andreas W., Universitätsmedizin Greifswald, Greifswald, Germany
  • Lindenmeyer, Maja, Nephrological Center, Munich, Germany
  • Moeller, Marcus J., University of Aachen, RWTH, Aachen, Germany
  • Amann, Kerstin U., Department of Nephropathology, Erlangen, Germany
  • Endlich, Karlhans, University Medicine Greifswald, Greifswald, Germany
  • Endlich, Nicole, University Medicine Greifswald, Greifswald, Germany
Background

Dedifferentiation and loss of podocytes are the major causes of chronic kidney disease. The basic helix-loop-helix (bHLH) transcription factor Tcf21 plays an important role for the differentiation of podocytes and is strongly expressed in mature podocytes in vivo. Tcf21 -/- mice die in the perinatal period due to the failure in the development of the lung and the kidney glomeruli.

Methods

Since parietal epithelial cells (PECs) are still under debate to be a type of progenitor cell for podocytes, we performed comparative gene expression analysis between freshly isolated podocytes, cultured primary PECs and cultured primary podocytes of mice. Furthermore, we performed ChIP-Seq analysis to identify new putative interaction partners and target genes of Tcf21.

Results

We identified 644 differentially regulated genes in freshly isolated podocytes in comparison to PECs and podocytes in culture. Tcf21 was identified as one of the most upregulated genes in freshly isolated podocytes (24- and 15-fold, respectively) as compared to PECs and podocytes, respectively, in culture.
Interestingly, the expression of Tcf21 in PECs induced multilobulation and budding of the nuclei, and the formation of micronuclei (MBM). Furthermore, we found an increased number of tetraploid cells. The multilobulation of nuclei was reversible after the addition of nocodazole and taxol indicating an involvement of microtubules.
By qRT-PCR and Western blot analysis we found that Tcf21 downregulates the transcription factor YY1. Co-expression of YY1 and Tcf21 rescued the formation of MBM. Moreover, we observed that Tcf21 levels regulate the expression of cyclins like cyclin D1 and cyclin D2, suggesting a role of Tcf21 in cell cycle control.
Additionally, by ChIP-Seq analysis we identified a genome-wide Tcf21-binding site (CAGCTG), which matched the CANNTG sequence that is the common E-box binding motif used by bHLH factors. Interestingly, many of the Tcf21 targets genes are involved in the regulation of the cell cycle, cell division, microtubule-based processes and chromosome segregation.

Conclusion

Taken together, Tcf21 is a transcription factor that appears to be importantly involved in the cell cycle regulation and function of podocytes.