title: Very early and transient vegetal-plate expression of SpKrox1, a Krüppel/Krox gene from Stronglyocentrotus purpuratus.
abstract: All endodermal and mesenchymal cells of the sea urchin embryo descend from the vegetal plate, a thickened epithelium of approximately 50 cells arising at the early blastula stage. Cell types that derive from the vegetal plate are specified conditionally by inductive interactions with underlying micromeres, but the molecular details of vegetal-plate specification remain unresolved. In a search for regulatory proteins that have roles in vegetal-plate specification, a screen was performed to clone Krüppel/Krox-related genes from a Strongylocentrotus purpuratus embryo cDNA library. One newly identified clone, named SpKrox1, contained four zinc fingers and a leucine zipper domain. SpKrox1 expression was low in unfertilized eggs, increased severalfold to the early blastula stage and decreased between the early gastrula and pluteus stages. SpKrox1 mRNA was first seen in macromeres of 16-cell stage embryos and was restricted to cells of the developing vegetal plate thereafter. Vegetal-plate expression corresponded to a ring of cells around the blastopore and overlapped the expression patterns of other genes with potential roles in vegetal plate-specification. As the vegetal-plate cells invaginated into the blastopore, SpKrox1 expression was lost, suggesting that its role was not in endoderm differentiation per se but rather in the initial establishment of the vegetal plate.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Texas M. D. Anderson Cancer Center, Houston 77030, USA.
authors.forename: W
authors.initials: W
authors.lastname: Wang
authors.forename: A H
authors.initials: AH
authors.lastname: Wikramanayake
authors.forename: M
authors.initials: M
authors.lastname: Gonzalez-Rimbau
authors.forename: A
authors.initials: A
authors.lastname: Vlahou
authors.forename: C N
authors.initials: CN
authors.lastname: Flytzanis
authors.forename: W H
authors.initials: WH
authors.lastname: Klein
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019521:Body Patterning / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000378:metabolism; D017403:In Situ Hybridization; D051741:Kruppel-Like Transcription Factors; D008969:Molecular Sequence Data; D012097:Repressor Proteins; D012617:Sea Urchins; D013997:Time Factors; D014018:Tissue Distribution; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism*; D014158:Transcription, Genetic / Q000235:genetics; D016335:Zinc Fingers / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; C106226:Krox1 protein, Strongylocentrotus purpuratus; D051741:Kruppel-Like Transcription Factors; D012097:Repressor Proteins; D014157:Transcription Factors