Thursday, April 25, 2024
4/25/2024
Project Summary / Abstract Approximately 1,000,000 Americans have end state renal disease and these numbers are increasing. Dialysis provides an essential but unsatisfactory palliative solution with high morbidity and high mortality. A kidney transplant can restore kidney function, but the number of transplants is insufficient for the patient population, and the numbers have not increased significantly over the last 20 years. Several groups have demonstrated the directed differentiation of kidney-like structures, kidney organoids, from mouse and human pluripotent stem cells. These advances highlight the need to generate an enhanced understanding of the critical processes underlying mammalian nephrogenic programs. Further, recent advances in our understanding of human kidney development from the McMahon group emphasize the importance of direct human studies. Consequently, we combine analysis across developing mouse and human kidney systems with human kidney organoids to examine key regulatory processes in the nephrogenic program. In Specific Aim 1, we will determine the epigenetic control mechanisms regulating normal mouse and human nephron progenitor states through extensive analysis of RNA-seq, ChIP-seq, ATAC-seq and HI-C datasets. The regulatory processes identified through these studies are interesting in their own right but serve also as a critical benchmark for in vitro efforts to generate normal nephron progenitor cells. In Specific Aim 2, we will determine the transcriptional mechanisms of Wnt/ß-catenin pathway mediated maintenance and commitment of nephron progenitor cells. Wnt signaling plays a central role in stem/progenitor regulation in a variety of organ systems. Recent advances in nephron progenitor culture and differentiation make the kidney an attractive model for unravelling the duality of Wnt pathway action on nephron progenitor cells. In Specific Aim 3, we will examine the role of canonical Wnt signaling in distal patterning of the developing nephron. In patterning the early nephron anlagen, several lines of evidence links Notch and Wnt signaling to proximal and distal fate-specification, respectively. We will examine the role of Wnt-signaling in distal development using human and optimized human pluripotent cell kidney organoid model system, genetically engineered to report on nephron patterning events. The anticipated research outcomes will identify critical regulatory mechanisms governing the maintenance, commitment and differentiation of stem/progenitor cell types of broad interest to researchers working across different organ systems. The studies will also enhance our understanding of human kidney development and educate effective therapeutic application of stem cell-derived kidney structures.
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