5-Methoxy-UTP

5-Methoxy-UTP is an analogue of the naturally occurring uridine triphosphate (UTP). Similar to N1-methylpseudouridine and pseudouridine modifications, 5-methoxyuridine is another common chemical modification used for in vitro mRNA synthesis in order to improve mRNA activity and reduce innate immune responses. Chemical modifications of mRNAs with 5-methoxyuridine, N1-methylpseudouridine and pseudouridine have been shown to significantly improve the expression of enhanced green fluorescent protein (eGFP) in a variety of cell lines, among which 5-methoxyuridine-modified eGFP mRNA is more stable than other eGFP mRNAs. In addition, replacing UTP with 5-methoxy-UTP in Cas9 mRNA has also been reported to reduce innate immune responses, making the broad use of Cas9 possible both in vitro and in vivo.

References:

1. Li B, Luo X, Dong Y. Effects of Chemically Modified Messenger RNA on Protein Expression. Bioconjugate Chemistry, 2016, 27(3): 849-853.

2. Vaidyanathan S, Azizian KT, Haque AKMA, et al. Uridine Depletion and Chemical Modification Increase Cas9 mRNA Activity and Reduce Immunogenicity without HPLC Purification. Molecular Therapy - Nucleic Acids, 2018, 12: 530-542.