Histone acetyltransferase activities of cAMP-regulated enhancer-binding protein and p300 in tissues of fetal, young, and old mice.

CBP, a protein that binds to cyclic adenosine monophosphate-regulated enhancer-binding protein, and homologue protein, p300, have histone acetyltransferase (HAT) activity and are important in gene transcription, although their physiological functions in vivo remain to be further elucidated. By using immunoprecipitation and HAT activity assay we have found that p300 and CBP have similar tissue patterns of HAT activities, with the highest level in the brain, a relatively high level in the lung, spleen, and heart, an intermediate level in testes and muscle, and a lower level in liver and kidney; that HAT activities of p300 and CBP are relatively stable with advancing age in most examined tissues, but in liver, muscle, and testes, the activities are attenuated with aging; and that HAT activities of p300 and CBP are high in the brain and liver of E14 fetal and newborn mice. These data suggest that the HAT activities of p300 and CBP are important for gene transcription involved in tissue-specific expression, aging, and developing processes.