Positive and negative signals from mesoderm regulate the expression of mouse Otx2 in ectoderm explants.
Otx2, a mouse homolog of the Drosophila orthodenticle gene, is first widely expressed in the epiblast but becomes progressively restricted to the anterior third of the embryo by the headfold stage. This progressive restriction correlates with the anterior migration of mesoderm in the embryo, suggesting that interactions with mesoderm may be involved in setting up the anterior domain of Otx2 expression in vivo. Using explant-recombination assays, we have obtained evidence that a positive signal from anterior mesendoderm is required to stabilize expression of Otx2 in vivo, whereas a negative signal from the later-forming posterior mesendoderm represses Otx2 expression in the posterior part of the embryo. We have also found that exogenous retinoic acid can mimic the effect of this negative signal and reduces the anterior domain of Otx2 expression.
Ang
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SL
Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Canada.
Conlon
R A
RA
Jin
O
O
Rossant
J
J
D000818:Animals; D046508:Culture Techniques; D004475:Ectoderm / Q000502:physiology*; D004627:Embryonic Induction / Q000502:physiology*; D015870:Gene Expression / Q000187:drug effects; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins; D017403:In Situ Hybridization; D008648:Mesoderm / Q000502:physiology*; D051379:Mice; D009419:Nerve Tissue Proteins / Q000235:genetics*; D051857:Otx Transcription Factors; D015534:Trans-Activators / Q000235:genetics*; D014212:Tretinoin / Q000494:pharmacology
D018398:Homeodomain Proteins; D009419:Nerve Tissue Proteins; D051857:Otx Transcription Factors; C497660:Otx2 protein, mouse; D015534:Trans-Activators; D014212:Tretinoin