The formation of a single ureteric bud (UB) at the proper location on the Wolffian duct (WD) is important to make a functional ureter, while complex patterns of UB branching morphogenesis are required for normal renal organogenesis. While many genes involved in these events have been identified, the genetic instructions must be translated into specific cellular responses (for example, mitosis, apoptosis, migration, adhesion) in order to shape and organize a complex 3-D structure like the urinary epithelium. While very little is known about the specific cellular behaviors that underlie epithelial morphogenesis in higher organisms, or how they are controlled, advances in genetic manipulation and imaging technologies now make it feasible to address such questions using mouse models. This project will focus on the cellular events that are regulated by the secreted factor GDNF, which signals through the Ret receptor tyrosine kinase. Ret signaling is needed to make a normal ureter and kidney, but how it influences the behavior of WD and UB epithelial cells in vivo remains to be defined. Ret-expressing cells at the tips of the branching UB are the main progenitors of the collecting duct system epithelium during kidney development, and they arise from a specific region of the Wolffian duct, the """"""""primary tip domain"""""""". Recent findings reveal that the primary tip domain is itself generated via Ret-dependent cell movements within the Wolffian duct. This raises several important questions: How are these cell movements controlled, and what is the role of GDNF/Ret signaling in Wolffian duct cell motility and guidance? What other genes and signaling pathways downstream of Ret are involved? Do similar cell movements underlie the growth and branching of the ureteric bud tip epithelium during kidney development? How else may Ret signaling affect the behavior of the epithelial progenitor cells at the UB tips? To address these questions, several methods will be used to genetically modify small numbers of WD or UB cells, and then to examine the effects of these alterations on cell behaviors in organ cultures, using time-lapse imaging, or in vivo. The proposed research should advance the field not only by extending to the cellular level our understanding of the role of GDNF/Ret signaling, but also by providing a paradigm for studying how other signaling systems affect the behavior of urinary epithelial cells during organogenesis. The information gained should also advance our understanding of the etiology of congenital urological and renal malformations, and may suggest new strategies to prevent or treat them.

Public Health Relevance

Understanding how the urinary system achieves its normal size and shape has important clinical implications, as defects can lead to obstruction, impaired function or even absence of the ureters and kidneys. The development of the urinary system affects the number of nephrons (blood-filtering units) that form in the kidney, which may influence the progression of renal diseases and hypertension. An understanding of the genes and cellular events that underlie ureter and kidney development may eventually permit treatments for congenital malformations, repair of damaged organs, or growth of artificial organs.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK083289-05
Application #
8485597
Study Section
Urologic and Kidney Development and Genitourinary Diseases Study Section (UKGD)
Program Officer
Hoshizaki, Deborah K
Project Start
2009-09-01
Project End
2014-05-31
Budget Start
2013-06-01
Budget End
2014-05-31
Support Year
5
Fiscal Year
2013
Total Cost
$421,810
Indirect Cost
$158,418
Name
Columbia University (N.Y.)
Department
Genetics
Type
Schools of Medicine
DUNS #
621889815
City
New York
State
NY
Country
United States
Zip Code
10032
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Riccio, Paul; Cebrian, Cristina; Zong, Hui et al. (2016) Ret and Etv4 Promote Directed Movements of Progenitor Cells during Renal Branching Morphogenesis. PLoS Biol 14:e1002382
Cebrian, Cristina; Asai, Naoya; D'Agati, Vivette et al. (2014) The number of fetal nephron progenitor cells limits ureteric branching and adult nephron endowment. Cell Rep 7:127-37
Packard, Adam; Georgas, Kylie; Michos, Odyssé et al. (2013) Luminal mitosis drives epithelial cell dispersal within the branching ureteric bud. Dev Cell 27:319-30
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Kuure, Satu; Chi, Xuan; Lu, Benson et al. (2010) The transcription factors Etv4 and Etv5 mediate formation of the ureteric bud tip domain during kidney development. Development 137:1975-9

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