Integration, transcription, and control of a Drosophila heat shock gene in mouse cells.

Mouse L cells were transformed with a cloned 3.6-kilobase (kb) segment of Drosophila melanogaster DNA carrying the 2.25-kb transcribed sequence for the Drosophila 70,000-dalton heat shock protein (hsp70) and 1.1 kb and 0.2 kb of 5' and 3' flanking DNA, respectively. Heat shock of one of three such transformed cell lines containing multiple copies of the intact Drosophila segment induced the abundant accumulation of transcripts of the Drosophila gene, with correct or nearly correct 5' and 3' termini. This provides evidence, in accord with earlier indications, that diverse eukaryotes, including vertebrates, have heat shock systems similar to that studied extensively in Drosophila. Our results suggest that the signals for heat shock transcription and the chromosomal sites with which they interact have been highly conserved in evolution and that the regulatory sequences controlling transcription of the gene for hsp70 lie within the 3.6-kb Drosophila segment.