Analysis of ATF2 gene expression during early Xenopus laevis development.

Activating transcription factor 2 (ATF2) is a cellular sequence-specific DNA-binding protein that mediates transcriptional activation by the adenovirus (Ad) E1A protein. In injected Xenopus laevis oocytes, E1A-induced transactivation requires an ATF2 recognition sequence within the responding promoters, thereby suggesting that ATF2 is present in oocytes and perhaps has a developmentally important function. As a first step in assessing this, an ATF2 cDNA was cloned and sequenced. The protein encoded by this cDNA contains 486 amino acids and is 92% identical to mammalian ATF2. ATF2 RNA and protein levels are very low in oocytes, but rise dramatically during blastulation. These high levels are maintained through gastrulation, but return to low levels during neurulation. In the blastula, ATF2 RNA and protein are virtually completely confined to cells of the animal pole. The temporal and spatial regulation of ATF2 suggests that it has an important function in early development.