GENE-REGULATION BY ANTISENSE RNA IN THE FISSION YEAST SCHIZOSACCHAROMYCES-POMBE

This report describes experiments designed to demonstrate the suitabil ity of the fission yeast Schizosaccharomyces pombe as a host for antis ense RNA. regulation. A lacZ gene-expressing yeast strain was construc ted and used as a host for the expression of a series of antisense RNA s complementary to various regions of the target lacZ mRNA. All lacZ a ntisense genes were placed under control of the thiamine-repressible n mt1 promoter of S. pombe and expressed from episomal plasmids. For eac h antisense plasmid a corresponding sense control plasmid was construc ted. All lacZ antisense genes were shown to express antisense RNAs of the expected size at equivalent steady-state levels. beta-Galactosidas e activity in transformed cells expressing the long, short 5' or short 3' lacZ antisense RNAs was shown to be reduced by 45%, 20%, and 10%, respectively, relative to control transformants. Further experiments i ndicated that antisense RNA regulation in this system was conditional and reversible, with the observed reduction of beta-galactosidase acti vity being dependent on the transcription of lacZ antisense RNA. Our r esults represent the first successful example of antisense RNA regulat ion of gene expression in yeast and establish S. pombe as an experimen tal model for the biochemical analysis of antisense RNA regulation.