The purpose of this project is to study the roles of two transcription factors, Cux-1 and Pod-1, in kidney development and renal cyst formation. Cux-1 is a homeodomain protein that functions as a transcriptional repressor of differentiation- specific genes. Studies using in situ hybridization have shown that Cux-1 is developmentally regulated in the kidney. Cux-1 is highly expressed during early stages of nephrogenesis then is down-regulated as nephrons mature. Expression of Cux-1 remains persistently elevated in polycystic kidneys from homozygous cpk mice. Down-regulation of Cux-1 may be required for normal nephrogenesis, and dysregulated expression of Cux-1 may contribute to cyst formation by interfering with nephron differentiation. To test these hypotheses, we will examine whether the expression of Cux-1 is increased in other forms of polycystic kidney disease. Genetic crosses will be performed to determine whether mutations of Cux-1 reduce cyst formation in cpk mutant mice. Cux-1 will be over-expressed in transgenic mice to determine whether increased expression is sufficient to cause cyst formation.
The second aim i s to study the role of a novel basic-helix-loop-helix protein, named Pod-1, in kidney development. Basic-helix-loop-helix (bHLH) proteins are transcription factors that are important in cell differentiation and tissue-specific gene expression. Pod-1, which is the first tissue-restricted bHLH protein that has been identified in the kidney, is expressed in developing podocytes and in mesenchymal cells at sites of epithelial-mesenchymal interaction. Antisense inhibition of Pod-1 blocks mesenchymal cell condensation and inhibits ureteric branching. Pod-1 deficient mice exhibit abnormalities in branching morphogenesis, glomerular and tubular differentiation, and vascular development. The proposed studies will characterize the biochemical and functional properties of Pod-1 in the developing kidney. Specific antibodies generated against Pod-1 will be used to determine the size and subcellular localization of the protein. The DNA-binding properties, protein-protein interactions, and transcriptional activity of Pod-1 will be determined. Studies will be performed to evaluate whether mesenchymal expression of Pod-1 affects branching morphogenesis. Collectively, these studies should provide fundamental insights into transcriptional regulation of kidney morphogenesis and cystogenesis.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK045678-08
Application #
6380751
Study Section
Special Emphasis Panel (ZRG1-SSS-G (06))
Program Officer
Wilder, Elizabeth L
Project Start
1992-09-30
Project End
2003-06-30
Budget Start
2001-09-01
Budget End
2002-08-31
Support Year
8
Fiscal Year
2001
Total Cost
$254,814
Indirect Cost
Name
University of Texas Sw Medical Center Dallas
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
City
Dallas
State
TX
Country
United States
Zip Code
75390