title: Wnt/β-catenin signaling reduces Bacillus Calmette-Guerin-induced macrophage necrosis through a ROS -mediated PARP/AIF-dependent pathway.
abstract: BACKGROUND
  Necrosis of alveolar macrophages following Mycobacterium tuberculosis infection has been demonstrated to play a vital role in the pathogenesis of tuberculosis. Our previous study demonstrated that Wnt/β-catenin signaling was able to promote mycobacteria-infected cell apoptosis by a caspase-dependent pathway. However, the functionality of this signaling in the necrosis of macrophage following mycobacterial infection remains largely unknown.
  
  
  METHODS
  Murine macrophage RAW264.7 cells were infected with Bacillus Calmette-Guerin (BCG) in the presence of Wnt/β-catenin signaling. The necrotic cell death was determined by cytometric assay and electronic microscopy; the productions of reactive oxygen species (ROS) and reduced glutathione (GSH) were measured by a cytometric analysis and an enzyme-linked immunosorbent assay, respectively; and the activity of poly (ADP-ribose) polymerase 1 (PARP-1)/apoptosis inhibition factor (AIF) signaling was examined by an immunoblotting assay.
  
  
  RESULTS
  The BCG can induce RAW264.7 macrophage cells necrosis in a dose- and time-dependent manner along with an accumulation of reactive oxygen species (ROS). Intriguingly, an enhancement of Wnt/β-catenin signaling shows an ability to reduce the mycobacteria-induced macrophage necrosis. Mechanistically, the activation of Wnt/β-catenin signaling is capable of inhibiting the necrotic cell death in BCG-infected RAW264.7 cells through a mechanism by which the Wnt signaling scavenges intracellular ROS accumulation and increases cellular GSH concentration. In addition, immunoblotting analysis further reveals that Wnt/β-catenin signaling is capable of inhibiting the ROS-mediated cell necrosis in part through a PARP-1/AIF- dependent pathway.
  
  
  CONCLUSIONS
  An activation of Wnt/β-catenin signaling can inhibit BCG-induced macrophage necrosis by increasing the production of GSH and scavenging ROS in part through a mechanism of repression of PARP-1/AIF signaling pathway. This finding may thus provide an insight into the underlying mechanism of alveolar macrophage cell death in response to mycobacterial infection.
authors.affiliation: Key Laboratory of Ministry of Education for Conservation and Utilization of Special Biological Resources in the Western China, Ningxia University, 539 W Helanshan Road, Xixia District, Yinchuan, Ningxia, 750021, China. nx_wuxiaol@163.com.|College of Life Science, Ningxia University, 539 W Helanshan Road, Xixia District, Yinchuan, Ningxia, 750021, China. nx_wuxiaol@163.com.
authors.forename: Xiaoling
authors.initials: X
authors.lastname: Wu
authors.affiliation: Key Laboratory of Ministry of Education for Conservation and Utilization of Special Biological Resources in the Western China, Ningxia University, 539 W Helanshan Road, Xixia District, Yinchuan, Ningxia, 750021, China. nx_dgc@163.com.|College of Life Science, Ningxia University, 539 W Helanshan Road, Xixia District, Yinchuan, Ningxia, 750021, China. nx_dgc@163.com.
authors.forename: Guangcun
authors.initials: G
authors.lastname: Deng
authors.affiliation: Key Laboratory of Ministry of Education for Conservation and Utilization of Special Biological Resources in the Western China, Ningxia University, 539 W Helanshan Road, Xixia District, Yinchuan, Ningxia, 750021, China. limingfm@126.com.|College of Life Science, Ningxia University, 539 W Helanshan Road, Xixia District, Yinchuan, Ningxia, 750021, China. limingfm@126.com.
authors.forename: Min
authors.initials: M
authors.lastname: Li
authors.affiliation: Key Laboratory of Ministry of Education for Conservation and Utilization of Special Biological Resources in the Western China, Ningxia University, 539 W Helanshan Road, Xixia District, Yinchuan, Ningxia, 750021, China. liyong7732@126.com.|College of Life Science, Ningxia University, 539 W Helanshan Road, Xixia District, Yinchuan, Ningxia, 750021, China. liyong7732@126.com.
authors.forename: Yong
authors.initials: Y
authors.lastname: Li
authors.affiliation: Key Laboratory of Ministry of Education for Conservation and Utilization of Special Biological Resources in the Western China, Ningxia University, 539 W Helanshan Road, Xixia District, Yinchuan, Ningxia, 750021, China. machnyan0411@163.com.|College of Life Science, Ningxia University, 539 W Helanshan Road, Xixia District, Yinchuan, Ningxia, 750021, China. machnyan0411@163.com.
authors.forename: Chunyan
authors.initials: C
authors.lastname: Ma
authors.affiliation: Key Laboratory of Ministry of Education for Conservation and Utilization of Special Biological Resources in the Western China, Ningxia University, 539 W Helanshan Road, Xixia District, Yinchuan, Ningxia, 750021, China. wyj@nxu.edu.cn.|College of Life Science, Ningxia University, 539 W Helanshan Road, Xixia District, Yinchuan, Ningxia, 750021, China. wyj@nxu.edu.cn.
authors.forename: Yujiong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Key Laboratory of Ministry of Education for Conservation and Utilization of Special Biological Resources in the Western China, Ningxia University, 539 W Helanshan Road, Xixia District, Yinchuan, Ningxia, 750021, China. erc1080@163.com.|College of Life Science, Ningxia University, 539 W Helanshan Road, Xixia District, Yinchuan, Ningxia, 750021, China. erc1080@163.com.|Ningxia key laboratory of clinical and pathogenic microbiology, the General Hospital of Ningxia Medical University, 804 S. Shengli Street, Yinchuan, Ningxia, 750004, China. erc1080@163.com.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Liu
mesh_terms: D000818:Animals; D051033:Apoptosis Inducing Factor / Q000378:metabolism*; D001500:BCG Vaccine / Q000276:immunology*; D002460:Cell Line; D004794:Enzyme Repression; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D008264:Macrophages / Q000276:immunology* / Q000382:microbiology / Q000473:pathology; D051379:Mice; D009336:Necrosis; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D060449:Wnt Signaling Pathway / Q000276:immunology; D051176:beta Catenin / Q000378:metabolism*
chemical_list: C494829:AIFM1 protein, human; D051033:Apoptosis Inducing Factor; D001500:BCG Vaccine; D017382:Reactive Oxygen Species; D051176:beta Catenin; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; D005978:Glutathione