Published in: Science vol. 286, no. 5441, pp. 955-958 (October 29, 1999):

Giacomo Cavalli ^1,2 and Renato Paro ¹

¹ Center for Molecular Biology (ZMBH), University of Heidelberg, Im Neuenheimer Feld 282,
69120 Heidelberg, Germany.

² Insitute of Human Genetics, 141, rue de la Cardonille, 34396 Montpellier, France.

The Drosophila Polycomb and trithorax group proteins act through chromosomal elements such as Fab-7 to maintain repressed or active gene expression, respectively. A Fab-7 element is switched from a silenced to a mitotically heritable active state by an embryonic pulse of transcription. Here, histone H4 hyperacetylation was found to be associated with Fab-7 after activation, suggesting that H4 hyperacetylation may be a heritable epigenetic tag of the activated element. Activated Fab-7 enables transcription of a gene even after withdrawal of the primary transcription factor. This feature may allow epigenetic maintenance of active states of developmental genes after decay of their embryonic regulators.