Vascular smooth muscle cells express a constitutive NF-kappa B-like activity.
The NF-kappa B/Rel family of transcription factors is commonly expressed in non-hematopoietic cells in an inactive form within the cytoplasm, complexed with an inhibitor I kappa B protein. Thus, it was surprising that NF-kappa B element-driven heterologous promoter-reporter gene constructs were active upon transient transfection into vascular smooth muscle cells (VSMCs). Here, we report that VSMCs express a constitutive nuclear NF-kappa B-like activity. In electrophoretic mobility shift assays, nuclear extracts demonstrated binding to a wild type NF-kappa B element but not to those mutated at nucleotides critical for Rel-protein DNA interaction. Binding was abrogated by the presence of I kappa B-alpha. Furthermore, addition of an antibody to the p50 subunit of classical NF-kappa B (but not p65, c-Rel, or RelB) resulted in supershifted complexes. Transactivation of element-driven constructs was negatively affected by co-transfection of a vector expressing a dominant negative p50 subunit, which can dimerize with other Rel subunits but not bind DNA. The long terminal repeat of the human immunodeficiency virus-1, which is driven in part by two NF-kappa B elements, displayed strong activity within VSMCs. This activity was abrogated upon co-transfection of the vector expressing the dominant negative p50 mutant. Taken together, these experiments indicate that VSMCs constitutively express a functional NF-kappa B-like trans-acting factor, which may play a significant role in the regulation of proliferation and viral infection of these cells.
Lawrence
R
R
Department of Biochemistry, Boston University Medical School, Massachusetts 02118.
Chang
L J
LJ
Siebenlist
U
U
Bressler
P
P
Sonenshein
G E
GE
D000818:Animals; D001483:Base Sequence; D002417:Cattle; D002478:Cells, Cultured; D005260:Female; D016325:HIV Long Terminal Repeat / Q000235:genetics; D008969:Molecular Sequence Data; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D009838:Oligodeoxyribonucleotides; D011485:Protein Binding; D011518:Proto-Oncogene Proteins / Q000502:physiology; D020569:Proto-Oncogene Proteins c-rel; D015533:Transcriptional Activation
D016328:NF-kappa B; D009687:Nuclear Proteins; D009838:Oligodeoxyribonucleotides; D011518:Proto-Oncogene Proteins; D020569:Proto-Oncogene Proteins c-rel