The accumulation of beta-catenin in the nuclei of specific blastomeres is a critical early step in animal development. In all deuterostomes (echinoderms and chordates/vertebrates) that have been studied, accumulation of beta-catenin in the nuclei of specific blastomeres along the axis of the cleavage stage embryo is one of the first indications of embryonic polarity. This differential """"""""nuclearization"""""""" of beta-catenin is essential for proper germ layer formation and the establishment of inductive centers. The sea urchin embryo is a powerful model system for studying beta-catenin nuclearization. The embryo develops externally and is optically transparent, facilitating the application of a wide variety of light optical technologies. The system is unique in that specific cell types can be isolated from early embryos in large quantities. Most of the molecules of the beta-catenin pathway have been cloned from sea urchin and a large number of molecular biological tools are available. Gene expression can be manipulated by expression of dominant negative constructs and by microinjection of """"""""morpholino"""""""" antisense oligonucleotides. The proposed work will identify the mechanisms that underlie beta-catenin nuclearization in early embryos. There are two major aims: 1) Using GFP-tagged proteins and time-lapse, 3-D confocal microscopy, the dynamics and turnover of key regulators of beta-catenin degradation will be studied in vivo. We will measure the half-life of beta-catenin in specific blastomeres of the early embryo, which will provide essential information concerning the cellular and molecular mechanisms of differential nuclearization. Through blastomere isolation experiments, we will test the role of cell-cell interactions in regulating beta-catenin nuclearization. 2) We will test three major models of GSK3 regulation along the embryo axis. In addition, using dominant negative constructs and morpholinos, we will examine the developmental function of two regulators of GSK3 activity, disheveled and Akt/PKB.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
5R01HD042251-04
Application #
7020692
Study Section
Cell Development and Function Integrated Review Group (CDF)
Program Officer
Tasca, Richard J
Project Start
2003-03-01
Project End
2008-02-28
Budget Start
2006-03-01
Budget End
2008-02-28
Support Year
4
Fiscal Year
2006
Total Cost
$239,781
Indirect Cost
Name
Carnegie-Mellon University
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
052184116
City
Pittsburgh
State
PA
Country
United States
Zip Code
15213
Leonard, Jennifer D; Ettensohn, Charles A (2007) Analysis of dishevelled localization and function in the early sea urchin embryo. Dev Biol 306:50-65