ABSTRACT
Oligonucleotides are widely used as effective tools to regulate gene expression and drugs for targeted gene therapy. Therefore, they are potentially useful for the treatment of viral, tumor and hereditary diseases. Therapeutic oligonucleotides include antisense oligonucleotide, small interference RNA (siRNA), Ribozyme, DNAzyme, anti-gene, CpG, decoy and aptamer. Therapeutic oligonucleotides usually carry certain modifications, such as phosphorothioates, fluoro or locked nucleic acids, to enhance the stability and specificity, and reduce the side-effects, because natural oligonucleotides have poor stability in vivo, low specificity and side effects. Now oligonucleotides are usually manufactured by chemical synthesis, with low purity and high cost. Here, we review a novel thermocyclic reaction for the amplification of oligonucleotides, referred to as Polymerase-endonuclease Amplification Reaction (PEAR) catalyzed by two thermostable enzymes. PEAR is simple, efficient, and stable. Comparing with traditional chemical synthesis, PEAR-based enzymatic production of oligonucleotides could be a robust alternative method for the large-scale production of therapeutic or non-therapeutic oligonucleotides.