Regulation of Oncogene Expression via Targeting i-Motif in Nucleic Acids

The basic molecules required for sustaining life on earth include carbohydrates, lipids, proteins, and nucleic acids (DNA and RNA). DNA is considered to be the building block of life and can adopt various types of secondary structures. Gehring et al. revealed for the first time that DNA sequences having long cytosine stretch can form unconventional secondary structures called i-Motifs [1]. These i-Motifs are very dynamic intercalated, quadruple-helical structures and known to exist under acidic conditions. These cytosine stretches are not erratically located throughout the genome but enriched in the promoter regions of several oncogenes within the genome and in telomeres, the terminal regions of chromosomes. The formation and stabilization of i-motif may play a crucial role in gene expression [2-4], such as, the stabilization of the human telomeric i-motif by carboxylated single-walled carbon nanotubes inhibit telomerase that leads to telomere uncapping, DNA damage response and apoptosis [5].