Ea. Wimmer et al., TRANS-ACTING AND CIS-ACTING REQUIREMENTS FOR BLASTODERMAL EXPRESSION OF THE HEAD GAP GENE BUTTONHEAD, Mechanisms of development, 53(2), 1995, pp. 235-245
The Drosophila gene buttonhead (btd) encodes a zinc-finger protein rel
ated to the human transcription factor Spl. btd is expressed in the sy
ncytial blastoderm embryo in a stripe covering the anlagen of the ante
nnal, intercalary and mandibular head segments. btd has been character
ized as a head gap gene, since these segments are deleted in btd mutan
t embryos. We report here that the cis-acting elements required for bt
d head stripe expression are contained in a 1 kb DNA fragment, located
about 3 kb upstream of the promoter. The four maternal coordinate sys
tems are necessary for correct btd head stripe expression, likely by a
cting through the 1 kb cis-acting control region. Expression of the bt
d head stripe depends on the anterior morphogen encoded by the gene bi
coid (bcd). bcd-dependent activation also involves the activity of the
morphogens of the posterior and dorsoventral systems, hunchback and d
orsal, respectively, which act together to control the spatial limits
of the expression domain. Finally, the terminal system takes part in t
he regulation of btd head stripe expression by enhancing activation at
low levels of activity and repression at high levels of activity.