BLyS BINDS TO B CELLS WITH HIGH AFFINITY AND INDUCES ACTIVATION OF THE TRANSCRIPTION FACTORS NF-kappaB AND ELF-1.
B lymphocyte stimulator (BLyS) is a novel member of the TNF family of proteins expressed by myeloid cells as membrane-bound and soluble forms. BLyS was shown to act specifically on B cells, inducing proliferation and immunoglobulin production both in vitro and in vivo. The present study was undertaken to characterize binding of radiolabeled BLyS to its cognate receptor on human B lymphocytes and examine intracellular events initiated by BLyS binding. Similar to other TNF family members, BLyS is present in solution as a homotrimer as determined by gel filtration chromatography and light scattering analysis. BLyS binding to B cells is specific as other TNF family members tested did not compete for(125)I-BLyS binding. Analysis of equilibrium binding of(125)I-labeled BLyS to purified human tonsillar B cells demonstrated saturable binding. Scatchard analysis of the binding data revealed a single class of high-affinity binding on human B cells with approximately 2600 binding sites per cell and an apparent dissociation constant (K(D)) of about 0.1 nM. In addition we report that BLyS binding to B cells results in the activation of NF-kappaB and the Ets family transcription factor, ELF-1, and in the induction of mRNA for Polo-like kinase (PLK).
Kanakaraj
P
P
Human Genome Sciences, Inc., Rockville, MD, 20850, USA. palanisamy_kanakaraj@hgsi.com
Migone
T S
TS
Nardelli
B
B
Ullrich
S
S
Li
Y
Y
Olsen
H S
HS
Salcedo
T W
TW
Kaufman
T
T
Cochrane
E
E
Gan
Y
Y
Hilbert
D M
DM
Giri
J
J
D053264:B-Cell Activating Factor; D001402:B-Lymphocytes / Q000378:metabolism*; D001665:Binding Sites; D003432:Cross-Linking Reagents; D004268:DNA-Binding Proteins / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D007457:Iodine Radioisotopes; D007700:Kinetics; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000737:chemistry / Q000378:metabolism*
D053264:B-Cell Activating Factor; D003432:Cross-Linking Reagents; D004268:DNA-Binding Proteins; D007457:Iodine Radioisotopes; D008565:Membrane Proteins; D016328:NF-kappa B; D011994:Recombinant Proteins; C505719:TNFSF13B protein, human; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha