FIG. 4.
Cell-type-specific differences in RNAi efficiency. (A) QRT-PCR analysis to determine expression of all A1 isoforms in thymocytes and FACS-sorted splenic B and T cells. Relative A1 expression levels are shown as the ratios of A1 mRNA to L32 mRNA for wild-type (light grey), U6Δ-shA1 (black), and U6-STOP-shA1 × CD19-cre mice (dark grey). (B) Downregulation of A1 mRNA in indicated cell types from indicated mouse strains. Black circles represent U6-STOP-shA1 × CD19-cre mice, and white symbols represent individual U6Δ-shA1 mice. Light grey bars show the average percentages of wild-type A1 mRNA levels. (C) Distribution of A1 isoforms A1a (black, not detected), A1b (grey), and A1d (white) in thymocytes and splenic B cells from U6Δ-shA1 mice or wild-type littermates. A1 cDNA from eachsample was PCR amplified using primers A1-s and A1-as (see Materials and Methods) and subcloned into a TOPO-TA cloning vector (Invitrogen). Individual clones were sequenced to distinguish between A1 isoforms.