WT1 controls antagonistic FGF and BMP-pSMAD pathways in early renal progenitors

Area of Science:

• Developmental Biology
• Molecular Biology
• Genetics

Background:

• Kidney organogenesis involves precise regulation of renal progenitor cell proliferation, differentiation, and apoptosis.
• The Wilms' tumour suppressor (Wt1) is crucial for progenitor survival, but its precise role in renal agenesis is unclear.

Purpose of the Study:

• To elucidate the molecular mechanisms by which Wt1 regulates renal progenitor cell fate during kidney development.
• To investigate the interplay between Wt1, fibroblast growth factor (FGF), and bone morphogenetic protein (BMP)/pSMAD signaling pathways in early kidney development.

Main Methods:

• Utilized a Wt1 mutant model to study kidney development.
• Investigated the effects of Wt1 loss on FGF and BMP/pSMAD signaling pathways.
• Assessed the impact of recombinant FGFs and BMPs, as well as pSMAD signaling inhibitors, on renal progenitor cell apoptosis.

Main Results:

• Loss of Wt1 function led to abolished fibroblast growth factor (FGF) signaling and induced bone morphogenetic protein (BMP)/pSMAD signaling in the metanephric mesenchyme.
• Addition of FGFs or inhibition of pSMAD signaling rescued Wt1 loss-induced progenitor cell apoptosis.
• Recombinant BMP4, but not BMP7, induced apoptosis in early kidney progenitors, which was suppressed by FGF co-addition.

Conclusions:

• Early renal progenitors exhibit sensitivity to pSMAD signaling.
• FGF and pSMAD signaling act antagonistically in kidney development.
• WT1 is identified as a key regulator of pro-survival FGF signaling pathway genes, crucial for preventing apoptosis in renal progenitors.