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.
Saarialho-Kere
U K
UK
Dermatology Division, Jewish Hospital, Washington University Medical Center, St. Louis, Missouri 63110.
Welgus
H G
HG
Parks
W C
WC
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