Loss of Sigma-1 Receptor Chaperone Promotes Astrocytosis and Enhances the Nrf2 Antioxidant Defense

Figure 5

Nrf2 is enhanced in the Sig-1R KO cells under MG132 treatment. (a) Primary astrocytes isolated from Sig-1R WT or KO neonatal brains were treated with DMSO or MG132 for 24 h. Cell lysates were collected, and the immunoblot showed that Nrf2 was increased in the KO cells compared with WT cells under MG132 treatment. (b) Isolated astrocyte cultures from Sig-1R WT or KO neonatal brains were treated with DMSO or MG132 for 24 h followed by staining with the Nrf2 and GFAP antibodies. MG132 induced the pronounced nuclear pattern of Nrf2 in WT and KO cultures, as shown by the arrow. (c) To obtain nuclear Nrf2 percentage, the number of nuclear Nrf2 positive cells was divided by the total cell numbers (as indicated by DAPI signal). The images were captured from 3-4 random fields per sample. (d) WT or Sig-1R KO HEK cells were transiently transfected with Flag-Nrf2 for 24 h and then treated with DMSO or MG132 for another 24 h. Nuclear fractions were collected to determine the Nrf2 expression pattern. Nrf2 was normalized to the internal control. The Nrf2 expression level in the WT DMSO-treated group was normalized to 1. A trend of increased Nrf2 was observed in the Sig-1R KO cells. Statistical analysis was performed using t-test. Error bar indicates SEM.

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