The Role of Unfolded Protein Response in Human Intervertebral Disc Degeneration: Perk and IRE1-α as Two Potential Therapeutic Targets

Figure 4

UPR activation regulated the synthesis of NPCs through the PERK and IRE1-α pathways. (a) The expression of PERK, ATF6, and IRE1-α proteins in degenerated and nondegenerated NP tissues was detected by IHC. Representative images are presented at the indicated magnifications. Scale bar, 50 μm. Compared with the controlled group, the presence of PERK and IRE1-α was significantly increased in degenerated tissues, whereas ATF6 was similar. (b) The expression of ATF6, IRE1-α, and PERK was downregulated after being transfected with PREK, ATF6, and IRE1-α siRNA as assayed by real-time PCR. (c) The expression of Agg, Col2, and SOX9 was significantly increased after knockdown of PERK and IRE1-α than ATF6 as assessed by western blot. β-Actin was used as an internal control. The representative results were from three independent experiments. The error bars represent the SD from the mean values.

(a)

(b)

(c)