SIRT1 Inhibits Apoptosis by Promoting Autophagic Flux in Human Nucleus Pulposus Cells in the Key Stage of Degeneration via ERK Signal Pathway

Figure 3

Overexpression or downregulation of SIRT1 enhances or inhibits autophagic flux and inhibits or increases apoptosis, respectively, in mild degenerative NP cells. (a) The levels of SIRT1 and autophagy-related proteins were detected by western blot. SIRT1 expression was significantly elevated in mild degenerative human NP cells transfected with LV-SIRT1. LC3II/I level was elevated and p62 level was significantly reduced after LV-SIRT1 transfection. (b) The apoptosis rate of mildly degenerative human NP cells was evaluated by flow cytometry. The apoptosis rate was significantly decreased in NP cells transfected with LV-SIRT1. (c) The levels of SIRT1 and autophagy-related proteins were detected by western blot. SIRT1 expression was significantly reduced in mild degenerative human NP cells treated with SIRT1-siRNA. LC3II/I level was reduced and p62 level was increased after SIRT1-siRNA treatment. (d) The apoptosis rate of mildly degenerative human NP cells was evaluated by flow cytometry. The apoptosis rate was increased in NP cells treated with SIRT1-siRNA. The relative protein expression of LC3II/I corresponds to the ratio of LC3II signal to LC3I signal; p62 and SIRT1 correspond to the ratio of p62 and SIRT1 signals, respectively, to β-actin signal. The values are shown as the of three independent experiments performed in triplicate. , .

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