Inhibition of bfl-1/A1 by siRNA inhibits mycobacterial growth in THP-1 cells by enhancing phagosomal acidification.
Virulent tubercle bacilli inhibit apoptosis to establish a safe environment within the host cells. Here, we report that NF-kappaB dependent antiapoptotic protein bfl-1/A1 plays an important role in this process. Both virulent and avirulent mycobacteria bearing THP-1 cells expressed considerable amount of bfl-1/A1 after 4 h of infection. However, after 48 h of infection, bfl-1/A1 expression was evident only in Mycobacterium tuberculosis H37Rv but not in M. tuberculosis H37Ra infected cells. When parallel experiments were performed with Human monocyte-derived macrophages (MDMs), differential expression of bfl-1/A1 mRNA was observed in case of M. tuberculosis H37Rv and M. tuberculosis H37Ra infection. siRNA mediated inhibition of bfl-1/A1 induced apoptosis in M. tuberculosis H37Rv infected THP-1 and MDMs. Reduction in intracellular mycobacterial growth was observed in bfl-1/A1 siRNA transfected, M. tuberculosis H37Rv infected THP-1 cells. Enhancement of phagosome-lysosome fusion was observed in bfl-1/A1 siRNA treated and M. tuberculosis H37Rv infected THP-1 cells. These results clearly indicated that differential expression of bfl-1/A1 in M. tuberculosis H37Rv and M. tuberculosis H37Ra infected THP-1 cells probably account for the difference in infection outcome.
Dhiman
Rohan
R
Division of Cell Biology and Immunology, Institute of Microbial Technology (CSIR), Chandigarh 160 036, India.
Kathania
Mahesh
M
Raje
Manoj
M
Majumdar
Sekhar
S
D000143:Acids / Q000737:chemistry; D017209:Apoptosis; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D002460:Cell Line; D002478:Cells, Cultured; D049452:Green Fluorescent Proteins / Q000737:chemistry; D006801:Humans; D006863:Hydrogen-Ion Concentration; D042541:Intracellular Space / Q000382:microbiology; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D008264:Macrophages / Q000166:cytology / Q000378:metabolism / Q000382:microbiology; D018613:Microscopy, Confocal; D015778:Minor Histocompatibility Antigens; D009000:Monocytes / Q000166:cytology / Q000378:metabolism* / Q000382:microbiology; D009169:Mycobacterium tuberculosis / Q000737:chemistry / Q000254:growth & development*; D010588:Phagosomes / Q000737:chemistry / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics*; D017382:Reactive Oxygen Species / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection
D000143:Acids; C096816:BCL2-related protein A1; D015778:Minor Histocompatibility Antigens; D019253:Proto-Oncogene Proteins c-bcl-2; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D008156:Luciferases; D053148:Caspase 3