A region in the coding sequence is required for high-level expression of murine histone H3 gene

Replication-dependent histone genes are expressed at high rates in S phase to provide the histone proteins required for chromosomal replication. Two genes, an H2a and H3 gene, located on chromosome 3 in the mouse and cloned together in a single 3-kilobase (plasmid MM614) restriction fragment are highly expressed. By transfecting mouse histone gene constructs into Chinese hamster ovary cells, we have identified a 110-nucleotide region within the coding sequence of the H3.2-614 gene that is required for high-level expression. Deletion of this region reduces expression of the gene by 20-fold. Additionally, the histone-coding region activates the human alpha-globin promoter, which is normally not expressed well in Chinese hamster ovary cells. Similar results with deletion constructions involving the H2a-614 gene suggest that an intragenic region plays an important role in transcription of these genes.