NF-kappa B regulates VCAM-1 expression on fibroblast-like synoviocytes.
Expression of VCAM-1 on synovial fibroblasts is a clinical hallmark of rheumatoid arthritis. The interaction of VCAM-1 and its integrin receptor very late Ag-4 is believed to be critically involved in the recruitment and retention of immune cells in the inflamed joints. To study the regulation of VCAM-1 in synovial fibroblasts, fibroblast-like synoviocytes (FLS) were isolated from the knee joints of normal mice and passaged repeatedly to obtain a homogeneous cell population. We have found that VCAM-1 is constitutively expressed on mouse FLS (mFLS) and that its surface expression is further increased after exposure to TNF-alpha. Nuclear translocation of transcription factor NF-kappa B including P50/P50 homodimer and P65/P50 heterodimer was activated by TNF-alpha treatment. In mFLS stably expressing a dominant-negative mutant of the inhibitory protein I-kappa B alpha- (mI-kappa B), which does not undergo proteolytic degradation, NF-kappa B remains in the cytosol and its activation in response to TNF-alpha is abolished. VCAM-1 protein expression after TNF-alpha stimulation was blocked in cells expressing the mI-kappa B. This effect is likely due to the loss of NF-kappa B-mediated transcription of VCAM-1, because the 5-fold increase in mRNA levels in response to TNF-alpha is absent in the mutant cells. To confirm these findings, we transduced mFLS with an adenoviral vector containing the mI-kappa B transgene. VCAM-1 expression was also blocked by mI-kappa B in this system, whereas cells transduced with a control adenoviral vector remained responsive to TNF-alpha. These results indicate that NF-kappa B mediates TNF-alpha-induced VCAM-1 expression on mFLS.
Li
P
P
Department of Microbiology and Immunology, Immunology/Rheumatology Unit, University of Rochester Medical Center, Rochester, NY 14642, USA.
Sanz
I
I
O'Keefe
R J
RJ
Schwarz
E M
EM
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D002478:Cells, Cultured; D003587:Cytomegalovirus / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism; D005347:Fibroblasts / Q000276:immunology / Q000378:metabolism* / Q000821:virology; D006801:Humans; D051550:I-kappa B Kinase; D051379:Mice; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D016328:NF-kappa B / Q000096:biosynthesis / Q000378:metabolism / Q000502:physiology*; D052002:NF-kappa B p50 Subunit; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D011995:Recombination, Genetic; D013583:Synovial Membrane / Q000166:cytology / Q000276:immunology / Q000378:metabolism* / Q000821:virology; D051996:Transcription Factor RelA; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000037:antagonists & inhibitors / Q000502:physiology; D019010:Vascular Cell Adhesion Molecule-1 / Q000096:biosynthesis* / Q000276:immunology
D004268:DNA-Binding Proteins; D016328:NF-kappa B; D052002:NF-kappa B p50 Subunit; D012333:RNA, Messenger; D051996:Transcription Factor RelA; D014409:Tumor Necrosis Factor-alpha; D019010:Vascular Cell Adhesion Molecule-1; D017346:Protein Serine-Threonine Kinases; C496559:CHUK protein, human; C496564:Chuk protein, mouse; D051550:I-kappa B Kinase; C496560:IKBKB protein, human; C496565:IKBKE protein, human; C496562:Ikbkb protein, mouse; C496566:Ikbke protein, mouse