Phenylbutyric Acid Rescues Endoplasmic Reticulum Stress-Induced Suppression of APP Proteolysis and Prevents Apoptosis in Neuronal Cells
Figure 11
PBA decreases ER stress induced apoptosis.
The cells were treated with vehicle control (1∶2000 DMSO) or the ER stress inducing agents: tunicamycin (5 µg/ml), thapsigargin (0.25 µM), or brefeldin A (5 µg/ml) in the presence or absence of PBA. A low and a high dose of PBA were used, 1 mM and 5 mM respectively, to assess concentration effects upon survival. The treatment was performed for 48 hours. After which, the detached cells were collected, spun down, and counted from triplicate plates on a standard hemocytometer. The number of detached cells increased by 3.8 fold (tunicamycin), 4.5 fold (thapsigargin), and 5.7 fold (BFA)—all of which were statistically different than basal levels (p<0.05) (A). With the addition of 1 mM PBA, the number of detached cells decreased to non-statistically significant levels in the tunicamycin and thapsigargin treated cells, while the numbers remained statistically different in the BFA treated cells. With 5 mM PBA co-treatment, the numbers of detached cells in all conditions were numerically and statistically indistinguishable from basal levels (A). The pycnotic nuclei were scored by an independent scientist blinded to the conditions. A minimum of 1000 cells were counted in each condition. The fraction of pycnotic nuclei are represented relative to the total number of cells counted (% of total). All three ER stress inducing agents elicited a two-three fold increase in pycnotic nuclei. The fraction of cells with pycnotic nuclei decreased with PBA treatment—in the thapsigargin treated cells, the number of pycnotic nuclei was identical to the untreated cells by 1 mM PBA, and by 5 mM PBA the fraction of cells with pycnotic nuclei reached basal levels in all three treatment groups (B).