Autosomal Dominant Polycystic Kidney Disease (ADPKD) is a systemic disease with variable expression that is characterized by cyst formation in ductal organs, principally the kidneys and liver, vascular aneurysms, cardiac valve defects and colonic diverticulae. Genetic studies have linked the defect to at least three loci, and identified two of the genes os PKD1 and PKD2. Biochemical studies associated cyst formation with abnormal epithelial proliferation, polarity and basement membrane composition, features that characterize, features that characterize the less mature epithelium of developing and regenerating kidneys. Polycystin 1, the product of PKD1, is a developmentally- regulated multi-spanning membrane protein with a large extracellular region consisting of a novel mosaic of protein-protein interaction domains. Polycystin 2, the product of PKD2 is a hexaspanner with cytoplasmic N- and C-termini and homology to a voltage-activated calcium channel. The ADPKD phenotype in patients with mutations in PKD1 or PKD2 differs in disease progression and severity but not in the spectrum of the organs involved. This suggests that the respective proteins, in conjunction with other interacting proteins, function as components of a common pathway of epithelial differentiation in which polycystin 1 serves as a sensor, and regulates a putative ion channel activity of polycystin 2. Our goals are to elucidate the elements of this pathway in order to understand its precise role in terminal epithelial differentiation. We will attempt to define the earliest events (cellular processes and genes) affected by the loss of polycystin 1. We also propose to identify extracellular ligands for polycystin 1, and determine how the interaction of its cytoplasmic regions with 14-3-3 proteins is modulated during differentiation.
These aims will be addressed using basic biochemical, immunochemical, molecular and cell biology techniques and making use of homozygous and heterozygous polycystin 1 knock out mice. The results of these studies should provide important insights into the mechanisms of epithelial morphogenesis during tabular maturation, identify possible modifiers, and suggest potential targets and approaches for therapeutic intervention that may significantly halt the progression of ADPKD.

Project Start
2000-03-01
Project End
2001-02-28
Budget Start
1998-10-01
Budget End
1999-09-30
Support Year
2
Fiscal Year
2000
Total Cost
$195,580
Indirect Cost
Name
Massachusetts General Hospital
Department
Type
DUNS #
City
Boston
State
MA
Country
United States
Zip Code
02199
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Mangos, Steve; Liu, Yan; Drummond, Iain A (2007) Dynamic expression of the osmosensory channel trpv4 in multiple developing organs in zebrafish. Gene Expr Patterns 7:480-4
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Obara, Tomoko; Mangos, Steven; Liu, Yan et al. (2006) Polycystin-2 immunolocalization and function in zebrafish. J Am Soc Nephrol 17:2706-18
Kramer-Zucker, Albrecht G; Olale, Felix; Haycraft, Courtney J et al. (2005) Cilia-driven fluid flow in the zebrafish pronephros, brain and Kupffer's vesicle is required for normal organogenesis. Development 132:1907-21
Drummond, Iain A (2005) Kidney development and disease in the zebrafish. J Am Soc Nephrol 16:299-304
Li, Zhixing; Stuart, Robert O; Eraly, Satish A et al. (2003) Debt91, a putative zinc finger protein differentially expressed during epithelial morphogenesis. Biochem Biophys Res Commun 306:623-8
Xu, G Mark; Gonzalez-Perrett, Silvia; Essafi, Makram et al. (2003) Polycystin-1 activates and stabilizes the polycystin-2 channel. J Biol Chem 278:1457-62

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