Knockdown of GBP1 inhibits BCG-induced apoptosis in macrophage RAW 264.7 cells via p38/JNK pathway

Alveolar macrophage apoptosis induced by Mycobacterium tuberculosis (Mtb) plays a significant role in mediating the pathogenesis of tuberculosis. There is growing evidence that guanylate-binding proteins (GBPs) are associated with different pathological processes such as microbial infection. However, it remains unclear whether GBPs can regulate the apoptosis of macrophages induced by Mtb. In this study, we investigated the potential effect of GBP1 on RAW 264.7 cell apoptosis during Bacillus Calmette-Guerin (BCG) infection. The results demonstrated that BCG could induce macrophage apoptosis and GBP1 upregulation. In addition, we explored the role of GBP1 in regulating BCG-induced RAW 264.7 cell apoptosis using small interfering RNAs targeting GBP1. The results showed that knockdown of GBP1 could attenuate BCG-induced apoptosis in RAW 264.7 cells. Moreover, we found that GBP1 knockdown decreased the levels of cleaved-Caspase 3 and cleaved-PARP-1, while decreased those of cleaved-Caspase 9, BAX, Cytochrome C and APAF1. These findings imply that GBP1 knockdown can prevent BCG-induced apoptosis through an endogenous apoptosis pathway. In addition, the mitochondrial membrane potential of macrophages was significantly increased after BCG infection, and GBP1 knockdown could alleviate this phenomenon. Furthermore, downregulation of GBP1 also attenuated BCG-induced accumulation of reactive oxygen species in macrophages. Mechanistically, GBP1 suppressed the phosphorylation of the target molecules in p38/JNK pathway, thus regulating the apoptosis of BGC-infected macrophages. Collectively, these findings reveal a significant role of GBP1 in mediating cell apoptosis in macrophages infected with BCG, and the molecular mechanism underlying its suppressive effect on BCG-induced apoptosis.