Distinct mechanisms regulate interstitial collagenase and 92-kDa gelatinase expression in human monocytic-like cells exposed to bacterial endotoxin.
We studied the mechanisms that govern the expression of interstitial collagenase and 92-kDa gelatinase in U937 cells, a human monocyte-like cell line, exposed to bacterial lipopolysaccharide (LPS), a potent inducer of metalloproteinase expression. U937 cells were differentiated by phorbol ester (phorbol 12-myristate 13-acetate (PMA)) and, 24 h later, were exposed to LPS for an additional 24 h. Enzyme-linked immunosorbent assay and Northern hybridization showed that PMA mediated an induction of collagenase and markedly stimulated the low basal levels of 92-kDa gelatinase. Subsequent exposure to LPS substantially increased the production of both enzymes. Nuclear runoff assay demonstrated that PMA regulated collagenase and 92-kDa gelatinase transcription. LPS also stimulated collagenase transcription but did not affect transcription of 92-kDa gelatinase. Consistent with the runoff data, the decay rate of collagenase mRNA did not differ between experimental treatments, but the half-life of gelatinase mRNA increased with exposure to LPS. Furthermore, in situ hybridization showed that 92-kDa gelatinase was expressed by all cells whereas collagenase was produced by a subpopulation of cells in both PMA- and PMA/LPS-exposed cultures, and similar findings were seen with LPS-activated human alveolar macrophages. These data indicate that divergent mechanisms control metalloproteinase expression in phagocytic cells and that enzyme production differs among macrophage subpopulations.
Dermatology Division, Jewish Hospital, Washington University Medical Center, St. Louis, Missouri 63110.
U K
UK
Saarialho-Kere
H G
HG
Welgus
W C
WC
Parks
D000328:Adult; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D017364:Collagenases / Q000096:biosynthesis / Q000235:genetics*; D003513:Cycloheximide / Q000494:pharmacology; D004247:DNA; D010450:Endopeptidases / Q000096:biosynthesis / Q000235:genetics*; D018093:Gelatinases; D006801:Humans; D017403:In Situ Hybridization; D008070:Lipopolysaccharides / Q000494:pharmacology; D008969:Molecular Sequence Data; D009000:Monocytes / Q000166:cytology / Q000201:enzymology*; D012333:RNA, Messenger / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014158:Transcription, Genetic
D008070:Lipopolysaccharides; D012333:RNA, Messenger; D004247:DNA; D003513:Cycloheximide; D010450:Endopeptidases; D017364:Collagenases; D018093:Gelatinases; D013755:Tetradecanoylphorbol Acetate