Patent ID: 7820632

Claim:
A method for producing a double stranded small interfering RNA (siRNA) molecule in a mammalian cell, comprising: introducing one or more vectors into a mammalian cell, wherein the one or more vectors comprise (i) a first cassette comprising a mammalian U6 RNA pol III promoter operatively linked to a first nucleic acid encoding the sense strand of a double stranded siRNA molecule, wherein the first nucleic acid is positioned at the first nucleotide of the transcript of the mammalian U6 RNA pol III promoter in the first cassette and (ii) a second cassette comprising a mammalian U6 RNA pol III promoter operatively linked to a second nucleic acid encoding the antisense strand of the double stranded siRNA molecule, wherein the second nucleic acid is positioned at the first nucleotide of the transcript of the mammalian U6 RNA pol III promoter in the second cassette, wherein the first cassette and the second cassette are in the same vector or are in separate vectors, wherein the double stranded siRNA molecule is specific for a target gene, and allowing transcription of the first and second nucleic acids in the cell, thereby producing the double stranded siRNA molecule, wherein the sense strand and the antisense strand of the double stranded siRNA molecule are not capped and wherein the double stranded siRNA molecule is produced in an amount suitable for inhibiting expression of the target gene.