Vascular cell adhesion molecule-1 gene expression during human smooth muscle cell differentiation is independent of NF-kappaB activation.
Vascular cell adhesion molecule-1 (VCAM-1) gene expression in cytokine-activated cells depends on two kappaB elements. Since VCAM-1 expression appears developmentally regulated and cytokine-inducible in smooth muscle cells (SMCs), we have studied the role of NF-kappaB in differentiated SMC VCAM-1 expression. Confluent SMCs were cultured either in a serum-free medium in order to induce differentiation, or in medium with serum, stimulated or not by tumor necrosis factor alpha (TNF-alpha). The expression of smooth muscle myosin heavy chain, a SMC marker, and VCAM-1 was induced concomitantly in serum-free medium, whereas only VCAM-1 expression was induced by cytokine-treatment. We showed that the p50 and p65 subunits of NF-kappaB were localized in the cytoplasm of differentiating SMCs, whereas they were translocated into the nucleus of TNF-alpha-activated SMCs. Electrophoretic mobility shift assays with VCAM-1 gene kappaB elements failed to detect any induction of DNA-protein complex with nuclear extracts of differentiating SMCs in contrast to the cytokine-activated SMC nuclear extracts. Furthermore, VCAM-1 mRNA induction was inhibited in TNF-alpha-stimulated SMCs, but not in differentiating SMCs, by pyrrolidine dithiocarbamate, an inhibitor of NF-kappaB protein activation. Taken together, these findings suggest that in contrast to TNF-alpha activation, NF-kappaB is not involved in VCAM-1 gene expression during SMC differentiation.
Lavie
J
J
INSERM Unité 441, Athérosclérose, Pessac 33600, France.
Dandré
F
F
Louis
H
H
Lamazière
J M
JM
Bonnet
J
J
D001483:Base Sequence; D002454:Cell Differentiation; D002478:Cells, Cultured; D017931:DNA Primers; D005786:Gene Expression Regulation; D006801:Humans; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D019010:Vascular Cell Adhesion Molecule-1 / Q000235:genetics*
D017931:DNA Primers; D016328:NF-kappa B; D012333:RNA, Messenger; D019010:Vascular Cell Adhesion Molecule-1