Expression of the nuclear coactivators CBP and p300 in developing craniofacial tissue.

cAMP regulatory element-binding protein (CREB)-binding protein (CBP) and its functional homolog, the adenovirus E1A -associated 300-kDa protein (p300) are nuclear coactivators and histone acetyltransferases that integrate signals from disparate pathways by bridging specific transcription factors to the basal transcription apparatus. Their role in patterning and development was suggested by studies in mice in which CBP and p300 expression was disrupted and by the human Rubinstein-Taybi syndrome, which is associated with mutations of CBP. The cAMP signal transduction pathway plays a critical role during development of the palate. The linkage between cAMP and expression of specific genes is mediated via activation of trans-acting deoxyribonucleic acid-binding proteins such as the nuclear CREB. For genes regulated by CBP- or p300-containing transcriptional complexes, rates of transcription will depend in part on cellular levels and distribution of CBP/p300. We have thus determined the temporal and spatial expression of CBP and p300 in murine embryonic palatal tissue. Both CBP and p300 proteins and messenger ribonucleic acids are expressed in palatal tissue on each d of palate development (days 12-14 of gestation), as measured by Western blotting and reverse-transcription polymerase chain reaction. Expression of both CBP and p300 was greatest on day 12 of gestation, suggesting that these transcriptional coactivators are developmentally regulated. Immunohistochemical analysis of CBP and p300 expression in the murine embryonic craniofacial region revealed a ubiquitous distribution for both proteins. These studies lay the groundwork for further investigations into the role of CBP and p300 in cellular signaling during craniofacial development.