SIRT1 Undergoes Alternative Splicing in a Novel Auto-Regulatory Loop with p53
Figure 2
SIRT1-ΔExon8 is expressed widely in mouse cells and tissues.
(A) Mouse SIRT1 splice-variant-specific PCR primers and siRNA. Schematic of mouse SIRT-FL coding mRNA sequence (737 residues; based on NM_019812.2, GI: 227430307) plus loci of primers used (arrows, below panel). The novel Exon7/9 splice junction and target loci of siRNA which selectively target mouse SIRT1-ΔExon8 (xΔ8*) or mouse SIRT1-FL (xFL*) are shown above panel. Similar to humans, mouse SIRT1 Exon8 is the largest coding Exon and translation of SIRT1-Exon9 remains in-frame in the mouse SIRT1-ΔExon8 transcript, generating a 553 residue protein. For mouse primer and siRNA sequences see Figures S13 and S15. (B) SIRT1-FL versus SIRT1-ΔExon8 expression across a range of normal mouse tissues. Mouse splice-variant-specific qRT-PCR of SIRT1-FL or SIRT1-ΔExon8 with respect to β-Actin using the delta-C(t) method (see Methods). Data is shown with respect to expression levels in brain. (C) Expression of SIRT1-FL in a panel of mouse cell lines. Mouse splice-variant-specific qRT-PCR was performed for SIRT1-FL and corrected by β-Actin levels as in (B) above. (D) Expression of SIRT1-ΔExon8 in a panel of mouse cell lines. Mouse splice-variant-specific qRT-PCR was performed for SIRT1-ΔExon8 and corrected by β-Actin levels as in (B) above. (E) Relative expression levels of SIRT1-FL versus SIRT1-ΔExon8 transcripts in a panel of mouse cell lines. The data in (C) and (D) above, which represents the relative expression of SIRT1-FL or SIRT1-ΔExon8 with respect to β-Actin by the delta-C(t) method, was used here to calculate the true relative ratio of SIRT1-ΔExon8/SIRT1-FL.