The regulation of TNF receptor mRNA synthesis, membrane expression, and release by PMA- and LPS-stimulated human monocytic THP-1 cells in vitro.
The regulation of the 55-kDa TNF receptor (TNF-R) mRNA synthesis, membrane expression, and TNF binding factor (BF) release was examined in resting and activated human monocytic THP-1 and human promyelocytic leukemia HL-60 cells in vitro. Cells were activated with phorbol myristate acetate (PMA) and bacterial lipopolysaccharide (LPS). TNF alpha cytolytic activity in the supernatant of THP-1 cells stimulated by PMA began to appear at 4 hr, reached a peak at 8 hr, and declined by 12 hr. For THP-1 cells stimulated with LPS, the peak of TNF alpha activity appeared at 4 hr and then declined. TNF alpha-binding sites on the cell membrane were down-regulated within 1 hr after PMA and LPS treatment and then reappeared 12 hr later. Fifty-five-kilodalton TNF-R mRNA expression during this time period did not correlate with the level of membrane TNF-binding site expression. Additional studies indicated the presence of a 30-kDa TNF-BF in the supernatants which appeared after 24 hr. These data suggest that activated THP-1 and HL-60 cells are capable of releasing TNF-BF into the supernatant and this material may be involved in the control of secreted TNF alpha activities.
Gatanaga
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T
Department of Molecular Biology and Biochemistry, University of California, Irvine 92717.
Hwang
C D
CD
Gatanaga
M
M
Cappuccini
F
F
Yamamoto
R S
RS
Granger
G A
GA
D001483:Base Sequence; D002462:Cell Membrane / Q000737:chemistry; D002478:Cells, Cultured; D005786:Gene Expression Regulation / Q000187:drug effects*; D006801:Humans; D007938:Leukemia / Q000378:metabolism; D008070:Lipopolysaccharides; D008969:Molecular Sequence Data; D009000:Monocytes / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis*; D011956:Receptors, Cell Surface / Q000032:analysis / Q000235:genetics*; D018124:Receptors, Tumor Necrosis Factor; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
D008070:Lipopolysaccharides; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha; D013755:Tetradecanoylphorbol Acetate