In many organisms, transcription of the zygotic genome begins during the
maternal-to-zygotic transition (MZT), which is characterized by a dramatic
increase in global transcriptional activities and coincides with embryonic stem
cell differentiation. In Drosophila, it has been shown that
maternal morphogen gradients and ubiquitously distributed general transcription
factors may cooperate to upregulate zygotic genes that are essential for pattern
formation in the early embryo. Here, we show that Drosophila
STAT (STAT92E) functions as a general transcription factor that, together with
the transcription factor Zelda, induces transcription of a large number of
early-transcribed zygotic genes during the MZT. STAT92E is present in the early
embryo as a maternal product and is active around the MZT. DNAβbinding
motifs for STAT and Zelda are highly enriched in promoters of early zygotic
genes but not in housekeeping genes. Loss of Stat92E in the
early embryo, similarly to loss of zelda, preferentially
down-regulates early zygotic genes important for pattern formation. We further
show that STAT92E and Zelda synergistically regulate transcription. We conclude
that STAT92E, in conjunction with Zelda, plays an important role in
transcription of the zygotic genome at the onset of embryonic development