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Abstract: PO0488

Stabilization of Hypoxia-Inducible Factors Leads to Profound Epigenetic Changes in Primary Human Tubular Cells

Session Information

Category: Anemia and Iron Metabolism

  • 200 Anemia and Iron Metabolism

Authors

  • Krüger, René, Universitatsklinikum Erlangen Medizinische Klinik 4 Nephrologie und Hypertensiologie, Erlangen, Bayern, Germany
  • Schiffer, Mario, Universitatsklinikum Erlangen Medizinische Klinik 4 Nephrologie und Hypertensiologie, Erlangen, Bayern, Germany
  • Schödel, Johannes, Universitatsklinikum Erlangen Medizinische Klinik 4 Nephrologie und Hypertensiologie, Erlangen, Bayern, Germany
  • Naas, Stephanie, Universitatsklinikum Erlangen Medizinische Klinik 4 Nephrologie und Hypertensiologie, Erlangen, Bayern, Germany
Background

Pharmacological stabilization of Hypoxia-inducible factors (HIFs) to induce erythropoietin expression presents a novel therapeutic approach to treat patients with renal anemia. Whereas general effects of HIFs on the transcriptome are well studied, insights in HIF-mediated alterations at the epigenetic level remain limited. The epigenetic landscape determines cellular identity and may be shaped by environmental factors such as hypoxia via HIF. In this study, we aim at generating a genome-wide atlas of the tubule-specific chromatin landscape while investigating the epigenetic plasticity of regulatory DNA elements provoked by HIF stabilization.

Methods

Primary tubular cells (PTC) were isolated from tumor nephrectomy specimens. We performed unbiased analyses of chromatin structure and HIF DNA-interactions using the Assay for Transposase Accessible Chromatin followed by sequencing (ATAC-Seq) and Chromatin Immunoprecipitation DNA-Sequencing (ChIP-seq), respectively. These epigenetic data sets were complemented with transcriptome information gained by RNA sequencing.

Results

ATAC-seq data generated in PTC obtained from four different individuals were combined to create a genome-wide landscape of chromatin accessibility comprising approx. 110 000 consensus regions. We validated cellular identity by benchmarking these sites against publicly available epigenomic data sets provided by ENCODE. Further characterization of chromatin activity was achieved by integration of ChIP-seq data for the histone mark H3K27ac. Pharmacological stabilization of HIF resulted in a remarkable change of chromatin accessibility yielding several hundred differentially open regions. Alterations of the chromatin coincided with HIF-binding events and HIF-mediated changes in mRNA expression suggesting a functional role for HIF in shaping chromatin accessibility in renal tubular cells.

Conclusion

Our genome-wide atlas of chromatin accessibility and activity in primary tubular cells represents a valuable reference data set for the investigation of tubule-specific features. Furthermore, our comprehensive approach allows for in-depth analysis of favourable as well as adverse epigenetic effects of HIF stabilizers in human tubular cells.