Development of the urinary collecting system depends on appropriate tubulogenesis and branching morphogenesis of the ureteric bud. Abnormal development of these structures and their connections with the bladder (e.g. ectopic ureteric orifice, intravesical ureterocele) are associated with considerable morbidity. A number of these anomalies predominate in women (e.g. intravesical ureterocele, Ask-Upmark syndrome). However, little is known about molecular mechanisms of tubulogenesis and branching in the ureteric tree, a complex process that is difficult to study in the intact embryo or by organ culture alone. For the purpose of identifying """"""""tubulogenic"""""""" and """"""""branching morphogenetic"""""""" gene products and elucidating their mechanism of action during development of the urinary collecting system, perhaps the best cell culture systems currently available utilize MDCK and IMCD cells in grown in collagen gels. When exposed to hepatocyte growth factor, the cells form branching tubules; the morphogenetic events are very similar to those in the developing ureteric tree. Considerable evidence indicating these models are highly relevant to development of the urinary collecting system has been obtained in the PI's lab. By applying a combination of biochemical, cellular and molecular approaches to these models, it may be possible to identify gene products critical for ureteric bud morphogenesis; abnormal expression or function of these gene products is likely to be responsible for developmental disorders of the urinary tract. Based on preliminary data from the PI's lab, it is hypothesized that such gene products include: 1) extracellular matrix proteins and their integrin receptors (tubulogenesis-promoting and inhibiting); and 2) extracellular proteases (e.g. collagenase, urokinase). Furthermore, data from the PI's lab indicates that multiple phosphorylation mechanisms modulate tubulogenesis and branching. This proposal seeks to: a) identify these candidate """"""""tubulogenic/branching morphogenetic"""""""" gene products and understand their regulation by phosphorylation (Northern analysis of ECM proteins, integrins and proteases, substrate gel assays for proteases, immunoprecipitation from 32P labeled cells); b) by perturbation of expression or function, establish whether these gene products are critical for tubulogenesis and branching in the MDCK and IMCD cell models (antisera and antisense oligonucleotides); and c) by perturbing expression or function (antisera and antisense oligonucleotides), determine if these gene products are critical for ureteric tree development in embryonic organ culture (histological, immunocytochemical and in situ analysis). Thus, the strengths of different in vitro models will be utilized to identify gene products essential for development of the urinary collecting system.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
7R01DK049517-06
Application #
6136429
Study Section
Diabetes, Endocrinology and Metabolic Diseases B Subcommittee (DDK)
Program Officer
Nyberg, Leroy M
Project Start
1994-09-01
Project End
1999-11-30
Budget Start
1999-07-01
Budget End
1999-11-30
Support Year
6
Fiscal Year
1998
Total Cost
Indirect Cost
Name
University of California San Diego
Department
Pediatrics
Type
Schools of Medicine
DUNS #
077758407
City
La Jolla
State
CA
Country
United States
Zip Code
92093
Bush, Kevin T; Sakurai, Hiroyuki; Steer, Dylan L et al. (2004) TGF-beta superfamily members modulate growth, branching, shaping, and patterning of the ureteric bud. Dev Biol 266:285-98
Steer, Dylan L; Shah, Mita M; Bush, Kevin T et al. (2004) Regulation of ureteric bud branching morphogenesis by sulfated proteoglycans in the developing kidney. Dev Biol 272:310-27
Stuart, Robert O; Bush, Kevin T; Nigam, Sanjay K (2003) Changes in gene expression patterns in the ureteric bud and metanephric mesenchyme in models of kidney development. Kidney Int 64:1997-2008
Sakurai, H; Bush, K T; Nigam, S K (2001) Identification of pleiotrophin as a mesenchymal factor involved in ureteric bud branching morphogenesis. Development 128:3283-93
Qiao, J; Bush, K T; Steer, D L et al. (2001) Multiple fibroblast growth factors support growth of the ureteric bud but have different effects on branching morphogenesis. Mech Dev 109:123-35
Zent, R; Bush, K T; Pohl, M L et al. (2001) Involvement of laminin binding integrins and laminin-5 in branching morphogenesis of the ureteric bud during kidney development. Dev Biol 238:289-302
Stuart, R O; Bush, K T; Nigam, S K (2001) Changes in global gene expression patterns during development and maturation of the rat kidney. Proc Natl Acad Sci U S A 98:5649-54
Stuart, R O; Pavlova, A; Beier, D et al. (2001) EEG1, a putative transporter expressed during epithelial organogenesis: comparison with embryonic transporter expression during nephrogenesis. Am J Physiol Renal Physiol 281:F1148-56
Pohl, M; Sakurai, H; Stuart, R O et al. (2000) Role of hyaluronan and CD44 in in vitro branching morphogenesis of ureteric bud cells. Dev Biol 224:312-25
Pohl, M; Sakurai, H; Bush, K T et al. (2000) Matrix metalloproteinases and their inhibitors regulate in vitro ureteric bud branching morphogenesis. Am J Physiol Renal Physiol 279:F891-900

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