Figure 6.

Depletion of SAMD9L rescues the proliferation arrest caused by ΔNp63α knockdown. (A) Cell proliferation was monitored by sulforhodamine B (SRB) assays following 5 d of ΔNp63α knockdown in H226 cell lines stably expressing shRNAs against the indicated ΔNp63α target genes. Results are presented as the ratio of absorbance (A510) after/before doxycycline treatment to induce p63 knockdown. (B) Time course of cell proliferation performed by direct cell counting. Cells (1 × 10⁶) were seeded at day 0. Cells were pretreated with doxycycline for 5 d prior to seeding to induce ΔNp63α knockdown. Isogenic H226 cell lines with stable SAMD9L knockdown or IGFBP3 knockdown were compared with ΔNp63α knockdown alone (Control). See Supplemental Figure 14 for a second shRNA for each of SAMD9L and IGFBP3. (C) ΔNp63α recruits subunits of the SRCAP complex and mediates H2A.Z incorporation to repress RNAPII at anti-proliferative genes in a mechanism that is autonomous of p53.