title: AMPD3 is involved in anthrax LeTx-induced macrophage cell death.
abstract: The responses of macrophages to Bacillus anthracis infection are important for the survival of the host, since macrophages are required for the germination of B. anthracis spores in lymph nodes, and macrophage death exacerbates anthrax lethal toxin (LeTx)-induced organ collapse. To elucidate the mechanism of macrophage cell death induced by LeTx, we performed a genetic screen to search for genes associated with LeTx-induced macrophage cell death. RAW264.7 cells, a macrophage-like cell line sensitive to LeTx-induced death, were randomly mutated and LeTx-resistant mutant clones were selected. AMP deaminase 3 (AMPD3), an enzyme that converts AMP to IMP, was identified to be mutated in one of the resistant clones. The requirement of AMPD3 in LeTx-induced cell death of RAW 264.7 cells was confirmed by the restoration of LeTx sensitivity with ectopic reconstitution of AMPD3 expression. AMPD3 deficiency does not affect LeTx entering cells and the cleavage of mitogen-activated protein kinase kinase (MKK) by lethal factor inside cells, but does impair an unknown downstream event that is linked to cell death. Our data provides new information regarding LeTx-induced macrophage death and suggests that there is a key regulatory site downstream of or parallel to MKK cleavage that controls the cell death in LeTx-treated macrophages.
authors.affiliation: Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA 92037, USA.
authors.forename: Sangun
authors.initials: S
authors.lastname: Lee
authors.forename: Yanhai
authors.initials: Y
authors.lastname: Wang
authors.forename: Sung Ouk
authors.initials: SO
authors.lastname: Kim
authors.forename: Jiahuai
authors.initials: J
authors.lastname: Han
mesh_terms: D000659:AMP Deaminase / Q000235:genetics; D000818:Animals; D000881:Anthrax / Q000473:pathology*; D000942:Antigens, Bacterial / Q000633:toxicity*; D001427:Bacterial Toxins / Q000633:toxicity*; D001483:Base Sequence; D015153:Blotting, Western; D016923:Cell Death / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D005098:Exotoxins / Q000633:toxicity*; D008264:Macrophages / Q000166:cytology / Q000187:drug effects* / Q000201:enzymology*; D051379:Mice; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction
chemical_list: D000942:Antigens, Bacterial; D001427:Bacterial Toxins; D005098:Exotoxins; C030325:anthrax toxin; D000659:AMP Deaminase