title: Notch signaling regulates expression of Mcl-1 and apoptosis in PPD-treated macrophages.
abstract: Macrophages are cellular targets for infection by bacteria and viruses. The fate of infected macrophages plays a key role in determining the outcome of the host immune response. Apoptotic cell death of macrophages is considered to be a protective host defense that eliminates pathogens and infected cells. In this study, we investigated the involvement of Notch signaling in regulating apoptosis in macrophages treated with tuberculin purified protein derivative (PPD). Murine bone marrow-derived macrophages (BMMs) treated with PPD or infected with Mycobacterium bovis Bacillus Calmette-Guérin (BCG) induced upregulation of Notch1. This upregulation correlated well with the upregulation of the anti-apoptotic gene mcl-1 both at the transcriptional and translational levels. Decreased levels of Notch1 and Mcl-1 were observed in BMM treated with PPD when a gamma secretase inhibitor (GSI), which inhibits the processing of Notch receptors, was used. Moreover, silencing Notch1 in the macrophage-like cell line RAW264.7 decreased Mcl-1 protein expression, suggesting that Notch1 is critical for Mcl-1 expression in macrophages. A significant increase in apoptotic cells was observed upon treatment of BMM with PPD in the presence of GSI compared to the vehicle-control treated cells. Finally, analysis of the mcl-1 promoter in humans and mice revealed a conserved potential CSL/RBP-Jκ binding site. The association of Notch1 with the mcl-1 promoter was confirmed by chromatin immunoprecipitation. Taken together, these results indicate that Notch1 inhibits apoptosis of macrophages stimulated with PPD by directly controlling the mcl-1 promoter.
authors.affiliation: Department of Microbiology, Faculty of Science, Chulalongkorn University, Bangkok 10330, Thailand. tanapat.p@chula.ac.th
authors.forename: Tanapat
authors.initials: T
authors.lastname: Palaga
authors.forename: Siriluk
authors.initials: S
authors.lastname: Ratanabunyong
authors.forename: Thitiporn
authors.initials: T
authors.lastname: Pattarakankul
authors.forename: Naunpun
authors.initials: N
authors.lastname: Sangphech
authors.forename: Wipawee
authors.initials: W
authors.lastname: Wongchana
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Hadae
authors.forename: Patipark
authors.initials: P
authors.lastname: Kueanjinda
mesh_terms: D053829:Amyloid Precursor Protein Secretases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000276:immunology; D000818:Animals; D017209:Apoptosis / Q000235:genetics / Q000276:immunology*; D001665:Binding Sites; D001854:Bone Marrow Cells / Q000187:drug effects / Q000276:immunology / Q000382:microbiology; D002460:Cell Line; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005786:Gene Expression Regulation; D006801:Humans; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein / Q000235:genetics / Q000276:immunology; D008262:Macrophage Activation; D008264:Macrophages / Q000187:drug effects / Q000276:immunology / Q000382:microbiology; D051379:Mice; D009163:Mycobacterium bovis / Q000276:immunology; D064549:Myeloid Cell Leukemia Sequence 1 Protein / Q000235:genetics / Q000276:immunology*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D051881:Receptor, Notch1 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000276:immunology*; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology*; D014373:Tuberculin / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein; C579094:Mcl1 protein, mouse; D064549:Myeloid Cell Leukemia Sequence 1 Protein; C497762:Notch1 protein, mouse; D034741:RNA, Small Interfering; D051881:Receptor, Notch1; D014373:Tuberculin; D053829:Amyloid Precursor Protein Secretases