Effects of HDAC9 silencing on HIF-1-dependent TfR1 upregulation and Sp1-dependent GPX4 reduction in SH-SY5Y cells subjected to OGD/Rx. A, D, Representative western blot and quantification of HIF-1 (A) or Sp1 (D) protein expression in SH-SY5Y cells treated with siHDAC9 or scrambled control (siCTL) or with MG132 (10 μM) at 72h after OGD/Rx (n = 3/5). *, p ≤ 0.05 versus normoxic control (CTL); #, p ≤ 0.05 versus siCTL or siCTL plus vehicle in hypoxic conditions. B, E, Chromatin immunoprecipitation performing by using antibodies for HIF-1 (B) or for Sp1 (E), and primers for TfR1 and GPX4 promoter sequences, respectively, in SH-SY5Y cells under normoxic conditions or treated with siCTL, siHDAC9, or with MG132 (10 μM) and then subjected to OGD/Rx 72h (n = 3/5). C, F, mRNA levels of TfR1 (C) and GPX4 (F) in SH-SY5Y cells treated with siCTL or siHDAC9 or MG132 at 72h after OGD/Rx. (n = 3); *, p ≤ 0.05 versus normoxic condition (CTL); #, p ≤ 0.05 versus siCTL or siCTL + vehicle in hypoxic conditions. Bars represent mean ± SD.