Characterization of an inducible promoter system to investigate decay of stable mRNA molecules

We have developed a system in which the decay of stable mRNAs can be studied without the use of inhibitors of transcription. The Drosophila hsp70 heat shock promoter linked to the bovine growth hormone (BGH) gene was used to establish stable cell lines in which the BGH gene is transcribed in a conditional manner. The BGH mRNA is synthesized only after induction at 43 degrees C. Following a brief period of re-equilibration at 37 degrees C during which transcription of the heat shock-driven gene ceases, the stable BGH mRNA decays with typical first-order kinetics. Hence, the decay of the mRNA can be studied without assumptions regarding radioactive labeling of precursor pools or transcriptional inhibitors. The system is applicable to any stable mRNA.