Lipopolysaccharide Inhibits Autophagy and Promotes Inflammatory Responses via p38 MAPK-Induced Proteasomal Degradation of Atg13 in Hepatic Stellate Cells

Figure 8

LPS induces Atg13 loss via proteasome-dependent degradation. (a) MG132 (0.5 μM, 8 h) increased expression of Atg13, while Baf A1 (200 nM, 8 h) did not affect expression of Atg13 in LX2 cells. (b) HEK 293 cells expressing vector or GST-Atg13 and Myc-ubiquitin were treated with MG132 (0.5 μM, 8 h) as indicated. Cell lysates were subject to Myc-tag or GST-tag affinity isolation and immunoblotted for Atg13 and ubiquitin expression. (c) LX2 cells expressing GST-Atg13 or not were treated with CHX (0-1 mg/mL, 2 h). (d) LX2 cells expressing GST-Atg13 were treated with LPS, MG132, or Anisomycin. (e) LX2 cells were treated with LPS, MG132, or Anisomycin as indicated; (f) LX2 cells expressing GST-Atg13 were treated with MG132; expression of ULK1, FIP200, and Atg5 was detected. (g, h) LX2 cells were treated with LPS, CHX, or MG132 as indicated; expression of pro-IL1β and secretion of IL-1β were detected.

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