Knockdown of miR-124 target CD164 by single-strand mimics, 24 h following transfection of HCT-116 at 2 nM and 10 nM. 2′-OH is denoted in red, 2′-fluoro in green, 2′-o-methyl in black, and 5′-phosphorylation in purple. “Duplex ctrl” is a miR-124 RNA duplex, and “Neg ctrl” is a nontargeting siRNA duplex. (A) Increased activity from single strands that are phosphorylated and fluorinated. miR-124 single strands containing different patterns of 2′-fluoro modifications, with or without 5′-phosphorylation. (B) When single-strand length is varied, maximum activity is seen for miR-124 single strands of length 19–22 nt. (C) 2′-o-methyl walkthrough of a 2′-fluoro and 5′-phosphorylated miR-124 single strand shows loss of activity when a 2′-o-methyl is placed at position 2.
