A conserved regulatory role for antisense RNA in meiotic gene expression in yeast

Abstract

A significant fraction of the eukaryotic genome is transcribed into RNAs that do not encode proteins, termed non-coding RNA (ncRNA). One class of ncRNA that is of particular interest is antisense RNAs, which are complementary to protein coding transcripts (mRNAs). In this article, we summarize recent studies using different yeasts that reveal a conserved pattern in which meiotically expressed genes have antisense transcripts in vegetative cells. These antisense transcripts repress the basal transcription of the mRNA during vegetative growth and are diminished as cells enter meiosis. While the mechanism(s) by which these antisense RNAs interfere with production of sense transcripts is not yet understood, the effects appear to be independent of the canonical RNAi machinery.

Figure 1. The RME2 antisense RNA controls IME4 expression

In cells of a or a mating type, RME2 is expressed and blocks expression of the IME4 coding gene. In a/a cells, the repressor a1/a2 inhibits RME2 transcription, allowing IME4 expression.

Figure 2. Sources of antisense RNA

A) An antisense RNA with a unique promoter. The coding region of a gene that is associated with an antisense RNA is shown as a dark blue box. The dashed black line with an arrowhead represents the sense transcript. The solid red line with arrowhead indicates the antisense RNA. B) An antisense RNA from a bidirectional promoter of a neighboring gene. The coding region of a gene that is associated with an antisense RNA is shown as a dark blue box. The dashed black line with an arrowhead represents the sense transcript. The coding region of a neighboring gene is shown as a light blue box and the transcript of the neighboring gene is indicated by the dashed red line. The solid red line with arrowhead indicates the antisense RNA. C) An antisense RNA created by an extended 3'UTR of a neighboring gene. The coding region of a gene that is associated with an antisense RNA is shown as a dark blue box. The dashed black line with an arrowhead represents the sense transcript. The coding region of a neighboring gene is shown as a light blue box. The solid red line with arrowhead indicates the antisense RNA.