Transcription of DNA into RNA is an essential process occurring in all living organisms. In eukaryotes, transcription takes place in the nucleus. Recently eukaryotic transcription has been re-considered. First, new techniques such as NET-sequencing have shown that eukaryotic genomes are pervasively transcribed producing thousands of noncoding RNAs that most of the times have an uncharacterized function. Second, transcription is not seen solely as the act of producing mRNA but can also contribute to gene regulation. In particular, it has been shown that antisense (AS) transcription participates under certain circumstances in the control of gene expression. The aim of this study is to characterize AS-mediated gene regulation of highly regulated genes in yeast Saccharomyces cerevisiae. At such loci, an AS transcription unit originates within the 3'UTR of the gene and spans over the corresponding Sense (S) gene to reach the promoter. It is proposed that AS transcription may regulate S transcription possibly by recruiting histone deacetylase complexes that in turn silence the gene. This work aimed at characterizing AS transcription-mediated gene regulation using PHO5 as a model gene. We used the CRISPRi system in order to strand-specifically block AS transcription and study the effect at the Sense promoter.