Regulation of Gene Expression

Our genetic machinery is regulated extensively and is the reason why each organ has cells that express a unique set of genes, even though all cells in our body have the same chromosomes. Regulation starts at the epigenetic level, controlling the unwinding of chromosomes from histones by methylation and acetylation. Transcription of mRNA is immensely regulated by the promoter regions on the DNA. mRNA can also be regulated posttranscriptionally by miRNA and siRNA. Translation of proteins and their modification by ubiquitination after synthesis represents another level of regulation. The application of this science in the treatment of cancer is explained in this chapter along with the mechanisms by which drugs like vorinostat, romidepsin, miravirsen, steroids, and bortezomib act.