Anthrax lethal factor represses glucocorticoid and progesterone receptor activity.
We report here that a bacterial toxin, anthrax lethal toxin (LeTx), at very low concentrations represses glucocorticoid receptor (GR) transactivation in a transient transfection system and the activity of an endogenous GR-regulated gene in both a cellular system and an animal model. This repression is noncompetitive and does not affect ligand binding or DNA binding, suggesting that anthrax lethal toxin (LeTx) probably exerts its effects through a cofactor(s) involved in the interaction between GR and the basal transcription machinery. LeTx-nuclear receptor repression is selective, repressing GR, progesterone receptor B (PR-B), and estrogen receptor alpha (ERalpha), but not the mineralocorticoid receptor (MR) or ERbeta. GR repression was also caused by selected p38 mitogen-activated protein (MAP) kinase inhibitors, suggesting that the LeTx action may result in part from its known inactivation of MAP kinases. Simultaneous loss of GR and other nuclear receptor activities could render an animal more susceptible to lethal or toxic effects of anthrax infection by removing the normally protective antiinflammatory effects of these hormones, similar to the increased mortality seen in animals exposed to both GR antagonists and infectious agents or bacterial products. These finding have implications for development of new treatments and prevention of the toxic effects of anthrax.
Webster
Jeanette I
JI
Section on Neuroendocrine Immunology and Behavior, National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA.
Tonelli
Leonardo H
LH
Moayeri
Mahtab
M
Simons
S Stoney
SS
Leppla
Stephen H
SH
Sternberg
Esther M
EM
D000818:Animals; D000942:Antigens, Bacterial; D001408:Bacillus anthracis; D001427:Bacterial Toxins / Q000494:pharmacology*; D019556:COS Cells; D002522:Chlorocebus aethiops; D003907:Dexamethasone / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005419:Flavonoids / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D007700:Kinetics; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D015735:Mifepristone / Q000494:pharmacology; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors; D011965:Receptors, Glucocorticoid / Q000037:antagonists & inhibitors*; D011980:Receptors, Progesterone / Q000037:antagonists & inhibitors*; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors; D014162:Transfection
D000942:Antigens, Bacterial; D001427:Bacterial Toxins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D011965:Receptors, Glucocorticoid; D011980:Receptors, Progesterone; D011994:Recombinant Proteins; C030325:anthrax toxin; D015735:Mifepristone; D003907:Dexamethasone; D020928:Mitogen-Activated Protein Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one