siRNA Modified with 2'-Deoxy-2'-C-methylpyrimidine Nucleosides

DELLAFIORE, MARÍA; AVIÑÓ, ANNA; ALAGIA, ADELE; MONTSERRAT, JAVIER M.; IRIBARREN, ADOLFO M.; ERITJA, RAMON

CHEMBIOCHEM

WILEY-V C H VERLAG GMBH

Año: 2018

1439-4227

(2´S)-2´-Deoxy-2´-C-methyluridine and (2´R)-2´-deoxy-2´-C-methyluridine were incorporated in the 3´-overhang region of the sense and antisense strands and in positions 2 and 5 of the seed region of siRNA duplexes directed against Renilla luciferase, whereas (2´S)-2´-deoxy-2´-C-methylcytidine was incorporated in the 6-position of the seed region of the same constructions. A dual luciferase reporter assay in transfected HeLa cells was used as a model system to measure the IC50 values of 24 different modified duplexes. The best results were obtained by the substitution of one thymidine unit in the antisense 3´-overhang region by (2´S)- or (2´R)-2´-deoxy-2´-C-methyluridine, reducing IC50 to half of the value observed for the natural control. The selectivity of the modified siRNA was measured, it being found that modifications in positions 5 and 6 of the seed region had a positive effect on the ON/OFF activity.