Abstract: TH-PO1079
Transcriptional Reprogramming by Wilms Tumor 1 and FoxC2 Mediates a Repair Response During Podocyte Injury: Studies in Mice and Human Kidney Organoids
Session Information
- Glomerular Diseases: Podocyte Biology - I
November 07, 2019 | Location: Exhibit Hall, Walter E. Washington Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Glomerular Diseases
- 1204 Podocyte Biology
Authors
- Ettou, Sandrine S., Boston Children's Hospital, Boston, Massachusetts, United States
- Jung, Youngsook L., Harvard Medical School, Boston, Massachusetts, United States
- Miyoshi, Tomoya, Brigham and Women's Hospital, Boston, Massachusetts, United States
- Hiratsuka, Ken, Brigham and Women's Hospital, Boston, Massachusetts, United States
- Morizane, Ryuji, Brigham and Women's Hospital, Boston, Massachusetts, United States
- Park, Peter, Harvard Medical School, Boston, Massachusetts, United States
- Kreidberg, Jordan A., Boston Children's Hospital, Boston, Massachusetts, United States
Background
We previously reported that WT1 is a master regulator of gene expression in podocytes, binding nearly all genes known to be crucial for maintenance of the glomerular filtration barrier. We have now performed ChIP-Seq for FoxC2 transcription factor that also binds nearly all the same target genes as WT1, suggesting that WT1 and FoxC2 act as a cell lineage-specific transcriptional activating complex in podocytes.
Methods
We used Adriamycin (ADR)-induced podocyte injury as a model for human Focal Segmental Glomerulosclerosis. WT1 and FoxC2 binding to enhancers and the transcriptional start sites of the Nphs2 and Synpo genes was determined by direct ChIP-qPCR at multiple time points after ADR-induced injury, using both Balb/C and mTmG Nphs2-Cre mice. We also integrated RNA-seq and WT1/FoxC2 ChIP-seq data sets to determine how transcriptional reprogramming occurs during the course of podocyte injury.
Results
WT1 and FoxC2 transiently increase after injury, before decreasing to low levels. Synpo and Nphs2 mRNA levels also transiently increase in response to increases in WT1 and FoxC2 binding. Interestingly, distinct patterns of WT1 and FoxC2 binding were observed dependent on the enhancer or transcriptional start site being interrogated. The transient increased expression after injury was also observed in human kidney organoids, allowing us to identify a window of opportunity for treating glomerular disease in humans.
ChIP-seq studies identified sets of WT1 binding sites only bound after treatment with ADR suggesting that WT1 may acquire new target genes during the response to injury.
Since transcription factors DNA binding is modulated by chromatin accessibility, we used immortalized podocytes as an in vitro model to study epigenetic reprogramming after treatment with ADR or knockdown of Wt1. Both treatments result in conversion from activating to repressive histone marks at WT1/FoxC2 bound-enhancers.
Conclusion
Our results demonstrate that WT1 and FoxC2 mediate transcriptional reprogramming during the course of podocyte injury, and specifically that decreased levels of WT1 result in epigenetic silencing of gene expression during the course of podocyte injury.
Funding
- NIDDK Support