TY - JOUR
T1 - Activating and repressing signals in head development
T2 - The role of Xotx1 and Xotx2
AU - Andreazzoli, Massimiliano
AU - Pannese, Maria
AU - Boncinelli, Edoardo
PY - 1997/5
Y1 - 1997/5
N2 - Xotx1 and Xotx2 are two Xenopus homologues of the Drosophila orthodenticle gene that are specifically expressed in presumptive head regions that do not undergo convergent extension movements during gastrulation. We studied the function of Xotx1 and compared it with that of Xotx2. Ectopic expression of each of the two genes has similar effects in impairing trunk and tail development. Experimental evidence suggests that posterior deficiencies observed in microinjected embryos are due to negative interference with convergent extension movements. Transplantations of putative tail-forming regions showed that, while Xotx1 overexpression inhibits tail organizer activity, Xotx2 overexpression is able to turn a tail organizer into a head organizer. Finally, Xotx1 and Xotx2 are activated by factors involved in head formation and repressed by a posteriorizing signal like retinoic acid. Taken together, these data suggest that Xotx genes are involved in head-organizing activity, They also suggest that the head organizer may act not only stimulating the formation of anterior regions, but also repressing the formation of posterior structures.
AB - Xotx1 and Xotx2 are two Xenopus homologues of the Drosophila orthodenticle gene that are specifically expressed in presumptive head regions that do not undergo convergent extension movements during gastrulation. We studied the function of Xotx1 and compared it with that of Xotx2. Ectopic expression of each of the two genes has similar effects in impairing trunk and tail development. Experimental evidence suggests that posterior deficiencies observed in microinjected embryos are due to negative interference with convergent extension movements. Transplantations of putative tail-forming regions showed that, while Xotx1 overexpression inhibits tail organizer activity, Xotx2 overexpression is able to turn a tail organizer into a head organizer. Finally, Xotx1 and Xotx2 are activated by factors involved in head formation and repressed by a posteriorizing signal like retinoic acid. Taken together, these data suggest that Xotx genes are involved in head-organizing activity, They also suggest that the head organizer may act not only stimulating the formation of anterior regions, but also repressing the formation of posterior structures.
KW - Convergent extension
KW - Head organizer
KW - Homeobox
KW - Otx1
KW - Otx2
KW - Tail organizer
KW - Xenopus laevis
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M3 - Article
C2 - 9165121
AN - SCOPUS:1842404775
VL - 124
SP - 1733
EP - 1743
JO - Development (Cambridge)
JF - Development (Cambridge)
SN - 0950-1991
IS - 9
ER -