title: Gata2 provides an early anterior bias and uncovers a global positioning system for polarity in the amniote embryo.
abstract: The first axis to be specified during vertebrate development is that between the site where gastrulation will begin and the opposite pole of the embryo (dorsoventral axis in amphibians and fish, anteroposterior in amniotes). This relies on Nodal activity, but different vertebrates differ in how this activity is positioned. In chick, the earliest known asymmetry is posterior expression of the TGFβ-related factor Vg1, close to the future Nodal expression domain. Here we show that the transcription factor Gata2 is expressed anteriorly before this stage. Gata2 influences the site of primitive streak formation and its role is independent from, and upstream of, Vg1 and Wnt. However, although Vg1 is required for streak formation, Gata2 does not act as an absolute anterior specifier, but provides an anterior bias. These findings point to previously unsuspected global determinants of polarity of the early amniote embryo.
authors.affiliation: Department of Cell and Developmental Biology, University College London, Gower Street, London, UK. federica.bertocchini@unican.es
authors.forename: Federica
authors.initials: F
authors.lastname: Bertocchini
authors.forename: Claudio D
authors.initials: CD
authors.lastname: Stern
mesh_terms: D000818:Animals; D019556:COS Cells; D016764:Cell Polarity; D002642:Chick Embryo; D002645:Chickens; D002522:Chlorocebus aethiops; D050989:GATA2 Transcription Factor / Q000378:metabolism*; D054262:Gastrulation; D055452:Growth Differentiation Factor 1 / Q000378:metabolism; D055457:Nodal Protein; D054240:Primitive Streak / Q000196:embryology*; D015398:Signal Transduction; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D051153:Wnt Proteins
chemical_list: D050989:GATA2 Transcription Factor; D055452:Growth Differentiation Factor 1; D055457:Nodal Protein; D016212:Transforming Growth Factor beta; D051153:Wnt Proteins