Embryology Research Today is a free monthly online journal that collates and summarizes the latest research about Embryology, including details on stem cells, reproduction, transplants, cloning.

Par-1 kinase establishes cell polarity and functions in Notch signaling in the Drosophila embryo.

Bayraktar J, Zygmunt D, Carthew RW

Department of Biochemistry, Molecular Biology and Cell Biology, 2205 Tech Drive, Northwestern University, Evanston, IL 60208, USA.

The Drosophila protein kinase Par-1 is expressed throughout Drosophila development, but its function has not been extensively characterized because of oocyte lethality of null mutants. In this report, we have characterized the function of Par-1 in embryonic and post-embryonic epithelia. Par-1 protein is dynamically localized during embryonic cell polarization, transiently restricted to the lateral membrane domain, followed by apicolateral localization. We depleted maternal and zygotic par-1 by RNAi and revealed a requirement for Par-1 in establishing cell polarity. Par-1 restricts the coalescing adherens junction to an apicolateral position and prevents its widespread formation along the lateral domain. Par-1 also promotes the localization of lateral membrane proteins such as Delta. These activities are important for the further development of cell polarity during gastrulation. By contrast, Par-1 is not essential to maintain epithelial polarity once it has been established. However, it still has a maintenance role since overexpression causes severe polarity disruption. Additionally, we find a novel role for Par-1 in Notch signal transduction during embryonic neurogenesis and retina determination. Epistasis analysis indicates that Par-1 functions upstream of Notch and is critical for proper localization of the Notch ligand Delta.

Published 9 February 2006 in J Cell Sci, 119: 711-21.
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