Patent ID: 8258286

Claim:
A nucleic acid encoding an artificial primary miRNA transcript (pri-miRNA) consisting of, in order of position, a 5′-flanking region, a first siRNA region, a loop region, a second siRNA region, and a 3′-flanking region, wherein the 5′-flanking region comprises: (a) a 5′-joining sequence contiguously linked to the first siRNA region, wherein the 5′ joining sequence consists of 5-7 nucleotides, (b) a 5′-bulge sequence positioned upstream from the 5′-joining sequence consisting of 1-10 nucleotides, and (c) a 5′-spacer sequence positioned upstream from the 5′-bulge sequence, wherein the 5′-spacer sequence is UGGUACCGUU (SEQ ID NO: 180).