Kidney Week

Abstract: TH-PO0320

SRSF3 and EPB41L5 Isoform Switching Reveals a Conserved Splicing Program of Podocyte Injury in FSGS

Session Information

• Glomerular Diseases: Omics
  October 22, 2026 | Location: Exhibit Hall A, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Glomerular Diseases

• 1401 Glomerular Diseases: Mechanisms, including Podocyte Biology

Authors

• Mattias, Francescapaola, Institute of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany

Francescapaola Mattias

• Tsoy, Olga, Institute for Computational Systems Biology, University of Hamburg, Hamburg, Germany

Olga Tsoy

• Iervolino, Anna, Biogem, Biology and Molecular Genetics Institute, Avellino, Italy

Anna Iervolino

• Simm, Stefan, Coburg University of Applied Sciences, Institute of Bioanalysis, Coburg, Germany

Stefan Simm, PhD

• Hammer, Elke, Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany

Elke Hammer, DrPH

• Gress, Alexander, Department of Drug Bioinformatics, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research (HZI), Saarbrücken, Germany

Alexander Gress

• Siegerist, Florian, Institute of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany

Florian Siegerist, MD

• Schindler, Maximilian, Institute of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany

Maximilian Schindler

• Lange, Tim, Institute of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany

Tim Lange, DrPH

• Ameling, Sabine, Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany

Sabine Ameling

• Kacprowski, Tim, Institute of Data Science in Biomedicine, Technische Universität Braunschweig, Braunschweig, Germany

Tim Kacprowski, PhD

• List, Markus, Data Science in Systems Biology, TUM School of Life Sciences, Technical University of Munich, Freising, Germany

Markus List, PhD

• Kalinina, Olga V., Department of Drug Bioinformatics, Helmholtz Institute for Pharmaceutical Research Saarland (HIPS), Helmholtz Centre for Infection Research (HZI), Saarbrücken, Germany

Olga V. Kalinina, MSc, PhD

• Capasso, Giovambattista, Biogem, Biology and Molecular Genetics Institute, Avellino, Italy

Giovambattista Capasso, MD, PhD

• Endlich, Karlhans, Institute of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany

Karlhans Endlich, MD

• Baumbach, Jan, Institute for Computational Systems Biology, University of Hamburg, Hamburg, Germany

Jan Baumbach

• Völker, Uwe, Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany

Uwe Völker

• Kliewe, Felix, Institute of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany

Felix Kliewe

• Endlich, Nicole, Institute of Anatomy and Cell Biology, University Medicine Greifswald, Greifswald, Germany

Nicole Endlich, PhD

Group or Team Name

• PodoHealthX

Background

Alternative splicing (AS) is emerging as a regulator of podocyte homeostasis, but its in vivo contribution to FSGS pathogenesis remains unknown. Based on our previous finding that AS dysregulation drives podocyte dysfunction in vitro (Mattias et al., 2025), we investigated whether splicing factors and their target proteins contribute to podocyte injury in vivo using a zebrafish larva model of FSGS.

Methods

At 4 days post-fertilization (dpf), transgenic zebrafish larvae were treated with 50 nM nifurpirinol (NFP) to induce podocyte-specific injury. Controls received 0.1% DMSO.
Glomeruli and whole larvae were collected at 5 dpf (24h post-injury) and 6 dpf (48h) for RNA sequencing.
To detect and quantify AS dynamics, we used rMATS, LeafCutter, and Whippet. Isoforms of interest were prioritized using IsoformSwitchAnalyzeR. Findings were validated in human FSGS glomeruli using immunofluorescence (IF) and public microarray datasets.

Results

Glomerular RNA sequencing revealed that podocyte injury triggered progressive transcriptomic dysregulation, with 1,007 and 2,299 differentially expressed genes at 24 and 48 h post-injury, respectively. Of these, 8.3% (5 dpf) and 12.4% (6 dpf) overlapped with human FSGS microarray data, confirming strong translational relevance.
Approximately 7,000 AS events were detected, predominantly exon skipping (~80%). Consistent with the transcriptomic data, the number of genes undergoing splicing dysregulation increased from 136 genes at 5 dpf to 612 at 6 dpf, consistently identified across three independent tools. Isoform switch prioritization highlighted SRSF3 and EPB41L5 as key candidates.
SRSF3, a key splicing factor, underwent a shift toward the shorter srsf3a-206 isoform, lacking a 38-amino-acid phospho-rich C-terminus, with a corresponding decreased usage of isoform-201. Increased SRSF3 protein levels were confirmed in human FSGS glomeruli by IF.
Similarly, EPB41L5, a podocyte adhesion protein, showed reduced overall expression accompanied by increased relative usage of a truncated isoform lacking the C-terminus (isoform-204). Decreased EPB41L5 protein was confirmed in human FSGS biopsies by IF and public microarray datasets, distinguishing FSGS from membranous glomerulonephritis.

Conclusion

This study highlights AS as a key post-transcriptional regulatory mechanism in podocyte injury, with SRSF3 and EPB41L5 as conserved mediators of podocyte dysfunction.