Figure 4. Bitopertin treatment modulates HRI activity and improves autophagy, resulting in optimization of the quality control process with amelioration of red cell survival.
(A) Wb analysis of HRI phosphorylation and eIF2αP levels in sorted 1.5 × 106 CD44+Ter119+FSChi spleen cells from Hbbth3/+ mice with and without bitopertin treatment (10 mg/kg/d, 28 days) (n = 3). (B) Left: Wb analysis of phospho-mTOR (p-mTOR), mTOR, Rab5, Lamp1, and p62 in reticulocyte-enriched fractions from WT and Hbbth3/+ mice with and without bitopertin treatment (n = 3; 10 mg/kg/d, 28 days). Catalase was used as a protein loading control. Right: Densitometric analyses of the immunoblot bands similar to those shown are presented. Data are shown as median and minimum/maximum (n = 4); *P < 0.05 compared with WT; °P < 0.05 compared with vehicle; 2-way ANOVA with Holm-Šídák test for multiple comparisons. (C) Hemichromes bound to the membrane in WT and Hbbth3/+ mice with and without bitopertin treatment (n = 3; 10 mg/kg/d, 28 days). Data are shown as median and minimum/maximum (n = 4); P < 0.05 compared with WT; °P < 0.05 compared with vehicle; 2-way ANOVA with Holm-Šídák test for multiple comparisons. (D) ROS levels in red cells of WT and Hbbth3/+ mice with and without bitopertin treatment (10 mg/kg/d, 28 days). Data are presented as median and minimum/maximum (n = 6); *P < 0.05 compared with vehicle-treated Hbbth3/+mice; °P <0.05 compared with vehicle. 2-way ANOVA with Holm-Šídák test for multiple comparisons. (E) Wb analysis of thioredoxin-reductase (Trx-R) and peroxiredoxin-2 (Prx2) in erythrocytes from WT and Hbbth3/+ mice with and without bitopertin treatment (n = 3; 10 mg/kg/d, 28 days). Catalase was used as a protein loading control (see Supplemental Figure 6, A and B, for densitometric analyses). (F) Red cell survival of CFSE-labeled red cells from WT and Hbbth3/+ mice with and without bitopertin treatment (n = 3; 10 mg/kg/d, 40 days). Data are presented as mean ± SD (n = 3) from each group; *P < 0.05 compared with WT; °P < 0.05 compared with vehicle; Wilcoxon’s signed-rank test for multiple comparisons.