A cytokine-selective defect in interleukin-1 beta-mediated acute phase gene expression in a subclone of the human hepatoma cell line (HEPG2).
Several well-differentiated human hepatoma cell lines (HepG2, Hep3B) have been used to identify factors which regulate hepatic gene expression during the host response to inflammation/tissue injury (acute phase response). Studies in these cell lines, as well as in primary cultures of rat, rabbit, and mouse hepatocytes, have demonstrated that interleukin-1 beta (IL-1 beta), tumor necrosis factor (TNF-alpha), and interferon-beta 2 (IFN-beta 2) each mediate changes in expression of several hepatic acute phase genes. In this study we identify a subclone of the HepG2 cell line in which there is a selective defect in IL-1 beta-mediated acute phase gene expression. Recombinant human IL-1 beta mediates an increase in synthesis of the positive acute phase complement protein factor B and a decrease in synthesis of negative acute phase protein albumin in the parent uncloned HepG2 cell line (HG2Y), but not in the subclone HG2N. Recombinant human IFN-beta 2 and TNF-alpha, however, regulate acute phase protein synthesis in the subclone HG2N; i.e. IFN-beta 2 and TNF-alpha increase synthesis of factor B and decrease synthesis of albumin in both HG2Y and HG2N cells. Equilibrium binding analysis with 125I-rIL-1 beta at 4 degrees C showed that both HG2N and HG2Y cells bind IL-1 beta specifically and saturably. HG2N and HG2Y possess 3.8 and 4.0 x 10(3) plasma membrane receptors/cell with affinities of 0.96 and 1.07 x 10(-9) M, respectively. Thus, the defect in this subclone of the HepG2 cell line is likely to involve the signal transduction pathway for the biological activity of IL-1 beta and will be useful in elucidation of this signal transduction pathway.
Perlmutter
D H
DH
Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri.
Colten
H R
HR
Adams
S P
SP
May
L T
LT
Sehgal
P B
PB
Fallon
R J
RJ
D000209:Acute-Phase Proteins / Q000235:genetics*; D000418:Albumins / Q000235:genetics; D001685:Biological Factors / Q000502:physiology*; D006528:Carcinoma, Hepatocellular / Q000235:genetics*; D003181:Complement C4 / Q000235:genetics; D011415:Complement Factor B / Q000235:genetics; D016207:Cytokines; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D007370:Interferon Type I / Q000494:pharmacology; D007375:Interleukin-1 / Q000502:physiology*; D008113:Liver Neoplasms; D012333:RNA, Messenger / Q000235:genetics; D011971:Receptors, Immunologic / Q000378:metabolism; D017472:Receptors, Interleukin-1; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D000209:Acute-Phase Proteins; D000418:Albumins; D001685:Biological Factors; D003181:Complement C4; D016207:Cytokines; D007370:Interferon Type I; D007375:Interleukin-1; D012333:RNA, Messenger; D011971:Receptors, Immunologic; D017472:Receptors, Interleukin-1; D014409:Tumor Necrosis Factor-alpha; D011415:Complement Factor B