Ci-FoxA-a is the earliest zygotic determinant of the ascidian anterior ectoderm and directly activates Ci-sFRP1/5.

摘要: This work focuses on the anteroposterior patterning of ectoderm in invertebrate chordate Ciona intestinalis . Previous indicated that, by eight-cell stage, anterior and posterior animal blastomeres have acquired different properties, including a differential responsiveness to inducing signals from underlying mesendoderm. Here, we investigated molecular basis this distinction. For this, studied regulation earliest marker specific for ectoderm, Ci-sFRP1/5 , which is activated at 64-cell stage. We first found that activation does not involve communication with other lineages. then identified, phylogenetic footprinting deletion analysis, short conserved minimal enhancer driving onset expression showed was direct target Ci-FoxA-a gene, FoxA/HNF3 orthologue expressed ectodermal mesendodermal lineages Gain- loss-of-function experiments revealed necessary sufficient within impose an identity, repress programme. Thus, constitutes major early zygotic determinant ascidian acting autonomously territory, prior vegetal inductions. Interestingly, while vertebrate FoxA2 are also involved regionalization they thought act during gastrulation control, mesendoderm, organizer signals. discuss evolution light our findings.