TRAF6 promotes Bacillus Calmette-Guérin-induced macrophage apoptosis through the intrinsic apoptosis pathway.
10.12122/j.issn.1673-4254.2022.09.02
- Author:
Qin Mei MA
1
;
Li LIU
1
;
Jia Lin YU
1
;
Zhao Qian GONG
1
;
Xiao Ping WANG
2
;
Xiao Ling WU
1
;
Guang Cun DENG
1
Author Information
1. Key Lab of Ministry of Education for Protection and Utilization of Special Biological Resources in Western China.
2. Fourth People's Hospital of Ningxia Hui Autonomous Region, Yinchuan 750021, China.
- Publication Type:Journal Article
- Keywords:
Bacillus Calmette-Guérin;
TRAF6;
apoptosis;
intrinsic apoptosis pathway;
macrophage
- MeSH:
Apoptosis;
BCG Vaccine;
Caspase 3/metabolism*;
Humans;
Intracellular Signaling Peptides and Proteins;
Macrophages;
Mycobacterium bovis/metabolism*;
Poly(ADP-ribose) Polymerase Inhibitors;
TNF Receptor-Associated Factor 6/metabolism*;
bcl-2-Associated X Protein/metabolism*
- From:
Journal of Southern Medical University
2022;42(9):1279-1287
- CountryChina
- Language:Chinese
-
Abstract:
OBJECTIVE:To investigate the role of tumor necrosis factor receptor-associated factor 6 (TRAF6) in regulating Bacillus Calmette-Guérin (BCG)-induced macrophage apoptosis.
METHODS:The expression of TRAF6 in peripheral blood samples of 50 patients with active tuberculosis (TB) and 50 healthy individuals were detected using quantitative real-time PCR (qPCR). RAW264.7 macrophages were infected with BCG at different MOI and for different lengths of time, and the changes in expressions of Caspase 3 and TRAF6 were detected with Western blotting and qPCR. In a RAW264.7 cell model of BCG infection with TRAF6 knockdown established using RNA interference technique, the bacterial load was measured and cell apoptotic rate and mitochondrial membrane potential (MMP) were determined with flow cytometry. The expression levels of TRAF6, Caspase 3, PARP, BAX and Bcl-2 in the cells were detected using Western blotting, and the expressions of TRAF6 and Caspase 3 were also examined with immunofluorescence assay.
RESULTS:The expression of TRAF6 was significantly upregulated in the peripheral blood of patients with active TB as compared with healthy subjects (P < 0.001). In RAW264.7 cells, BCG infection significantly increased the expressions of Caspase 3 and TRAF6, which were the highest in cells infected for 18 h and at the MOI of 15. TRAF6 knockdown caused a significant increase of bacterial load in BCG-infected macrophages (P=0.05), lowered the cell apoptotic rate (P < 0.001) and reduced the expressions of Caspase 3 (P=0.002) and PARP (P < 0.001). BCG-infected RAW264.7 cells showed a significantly increased MMP (P < 0.001), which was lowered by TRAF6 knockdown (P < 0.001); the cells with both TRAF6 knockdown and BCG infection showed a lowered BAX expression (P=0.005) and an increased expression of Bcl-2 (P=0.04).
CONCLUSION:TRAF6 promotes BCG-induced macrophage apoptosis by regulating the intrinsic apoptosis pathway.
