PROJECT SUMMARY/ABSTRACT
This NIH Mentored Career Development Award describes a three-year proposal providing the training and
mentorship necessary for the candidate to develop into an independent investigator studying the genetic and
molecular regulation of kidney development, with a specific focus on how mutations in Wilms tumor 1 (Wt1)
affect cell lineage crosstalk in the developing kidney. To accomplish this, the candidate has developed a
detailed career development plan integrating the outstanding mentorship and scientific environment at UT
Southwestern with focused training in bioinformatics and in-vitro techniques to successfully transition to
independence. Wt1, the first gene identified in Wilms tumor, regulates multiple aspects of normal renal
development and has been previously shown to play a critical role in nephron progenitor cell (NPC)
differentiation. Further examination of mutant kidneys with Wt1 loss-of-function specifically targeting the NPC
lineage (Six2cre;Wt1c/c) shows additional effects on the nephrogenic stroma, with an expansion of stromal
progenitor cells, disruptions in stromal patterning, and an increase in expression of several stromal markers
previously shown to be upregulated in Wilms tumors, leading to the hypothesis that signals from the NPCs
and/or early nephron structures non-autonomously regulate stromal development. The testing of this
hypothesis will interrogate how NPC-to-stromal crosstalk directs stromal progenitor maintenance and/or
differentiation in normal kidney development, which will be accomplished through two proposed aims. In aim 1,
experiments utilizing genetically engineered mouse models are directed at determining how signals from
nephron lineage derived cells regulate the nephrogenic stroma. To do this, stromal proliferation, apoptosis, and
patterning will be examined in mutant mouse models targeting different populations of the nephron lineage (ie:
self-renewing NPCs vs. early nephron structures) in comparison to the effects on the stroma identified in
Six2cre;Wt1c/c mutant kidneys. Aim 2 will investigate the mechanism(s) of NPC-to-stromal crosstalk, using
bioinformatics to identify candidate receptor/ligand interactions and in-vitro assays to functionally validate these
pathways by determining if disrupting specific signaling pathways results in stromal defects in control kidneys,
and likewise, if restored signaling pathways can rescue normal stromal differentiation in mutant kidney
explants. Given that advances in renal development research have significantly contributed to the
understanding of Wilms tumor, and vice versa, with the study of Wilms tumor biology leading to advances in
developmental nephrology, the aims outlined in this proposal have the potential to further uncover how intricate
reciprocal signaling interactions regulate progenitor cell proliferation and/or differentiation in normal kidney
development and provide the foundation for future work examining how disruptions in progenitor cell crosstalk
between the nephron and stromal lineages may alter the embryonic microenvironment and predispose to the
development of Wilms tumor.