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. 2009 Apr 2;4(4):e5067. doi: 10.1371/journal.pone.0005067

Figure 7. MEOX2 induces senescence through transcriptional activation of p16INK4a.

Figure 7

(A) MEOX2 activates p16INK4a expression. Fibroblasts infected with retroviral constructs expressing the indicated cDNA (top) were harvested 9 days postinfection, and whole cell extracts assayed by western blot with the indicated antibodies (left). Bid serves as a loading control. Band intensities relative to the EGFP control are indicated. (B) MEOX2 binds to the p16INK4a promoter. Fibroblasts stably infected with a retroviral construct expressing hemagglutinin (HA)-tagged MEOX2 were harvested 15 days postinfection and subjected to chromatin immunoprecipitation with HA, PolII, or preimmune IgG antibodies. The resulting chromatin was assayed for enrichment of the indicated sequences by semiquantitative PCR with increasing cycle numbers. Band intensities relative to the input are indicated for the higher PCR cycle number; (0) indicates values at or below background intensity. The p16 primers amplified a fragment located 970 to 621 bp upstream of the INK4a ATG site, which is selectively enriched by MEOX2-HA immunoprecipitation. GAPDH and an amplicon located 5 kilobases upstream of the INK4a coding sequence (“p16 upstr”) serve as controls.