Ettensohn, Charles A. and Illies, Michele R. and Oliveri, Paola and De Jong, Deborah L. (2003) Alx1, a member of the Cart1/Alx3/Alx4 subfamily of Paired-class homeodomain proteins, is an essential component of the gene network controlling skeletogenic fate specification in the sea urchin embryo. Development, 130 (13). pp. 2917-2928. ISSN 0950-1991 http://resolver.caltech.edu/CaltechAUTHORS:ETTdev03
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In the sea urchin embryo, the large micromeres and their progeny function as a critical signaling center and execute a complex morphogenetic program. We have identified a new and essential component of the gene network that controls large micromere specification, the homeodomain protein Alx1. Alx1 is expressed exclusively by cells of the large micromere lineage beginning in the first interphase after the large micromeres are born. Morpholino studies demonstrate that Alx1 is essential at an early stage of specification and controls downstream genes required for epithelial-mesenchymal transition and biomineralization. Expression of Alx1 is cell autonomous and regulated maternally through ß-catenin and its downstream effector, Pmar1. Alx1 expression can be activated in other cell lineages at much later stages of development, however, through a regulative pathway of skeletogenesis that is responsive to cell signaling. The Alx1 protein is highly conserved among euechinoid sea urchins and is closely related to the Cart1/Alx3/Alx4 family of vertebrate homeodomain proteins. In vertebrates, these proteins regulate the formation of skeletal elements of the limbs, face and neck. Our findings suggest that the ancestral deuterostome had a population of biomineral-forming mesenchyme cells that expressed an Alx1-like protein.
|Additional Information:||Copyright © 2003 The Company of Biologists Limited. Accepted 27 March 2003. We thank M. Peeler for performing Alx1 northern blots, G. Wessel and D. McClay for antibodies, and the anonymous reviewers for their comments. This research was supported by NSF Grant IBN-0128140 to C.A.E. D. DeJong received support from a Carnegie Mellon SURG grant.|
|Subject Keywords:||Sea urchin embryo, Early development, Fate specification, Skeletogenesis, Primary mesenchyme cells, Alx1, Cart1, Biomineralization, Epithelial-mesenchymal transition, Alx3, Alx4|
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|Deposited On:||22 Oct 2008 20:36|
|Last Modified:||26 Dec 2012 10:26|
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