Expression of a Drosophila heat‐shock protein in Xenopus oocytes: conserved and divergent regulatory signals

• Published in: The EMBO journal Vol. 1; no. 12; pp. 1583 - 1588
• Main Authors: Bienz, M., Pelham, H.R.
• Format: Journal Article
• Language: English
• Published: England 01.01.1982
• Subjects: Animals; Cloning, Molecular; Drosophila; Drosophila melanogaster - genetics; Drosophilidae; Female; Genes; Genes, Regulator; Heat-Shock Proteins - genetics; Hot Temperature; Oocytes - metabolism; Protein Biosynthesis; RNA, Messenger - genetics; Transcription, Genetic; Xenopus
• ISSN: 0261-4189; 1460-2075
• DOI: 10.1002/j.1460-2075.1982.tb01359.x

On injection of cloned Drosophila hsp70 heat‐shock genes into Xenopus oocytes, heat‐inducible expression is observed: the level of correctly initiated transcripts is increased 20‐ to 100‐fold on heat shock at 34 degrees C. We show that this induction is due to activation of the heat‐shock gene promoter, and that the DNA sequences required for induction lie between 10 and 66 bases upstream from the transcription start site. Most heat‐induced transcripts have a correct 3′ end, and hsp70 mRNA activity is detectable after extraction of the RNA from oocytes and subsequent in vitro translation. Drosophila heat‐shock protein (hsp70) is synthesised in the injected oocytes after heat‐shock, but only at low temperature. Under heat‐shock conditions, Drosophila hsp70 mRNA translation is reduced 10‐fold as is translation of the normal (25 degrees C) mRNAs, whereas translation of the endogenous Xenopus hsp70 mRNA is strongly induced. Translation of Drosophila heat‐shock mRNAs extracted from flies and injected into the oocytes is also reduced by heat‐shock. This suggests that Xenopus oocytes do not recognise the translational regulatory signals of Drosophila heat‐shock mRNAs. In contrast, the signals for heat‐induced transcription must be strongly conserved between Xenopus and Drosophila.