Combining two mutations of human interleukin-6 that affect gp130 activation results in a potent interleukin-6 receptor antagonist on human myeloma cells.
The pleiotropic cytokine interleukin-6 (IL-6) interacts with the specific ligand binding subunit (IL-6R alpha) of the IL-6 receptor, and this complex associates with the signal-transducing subunit gp130 (IL-6R beta). Human IL-6 acts on human and murine cells, whereas murine IL-6 is only active on murine cells. The construction of a set of chimeric human/murine IL-6 proteins has recently allowed us to define a region (residues 43-55) within the human IL-6 protein, which is important for the interaction with gp130. Subdividing this region shows that mainly residues 50-55 of the human IL-6 are necessary for this interaction. Recently, another human IL-6 double mutant (Q159E and T162P) showed reduced affinity to gp130 but residual activity on the human myeloma cell line XG-1. Into this IL-6 mutant we introduced the murine residues 43-49 or 50-55 together with two point mutations, F170L and S176A, which had been reported to increase the affinity of IL-6 to the IL-6R alpha. The resulting IL-6 molecule, which contained the murine residues 50-55, was inactive on human myeloma cells and in addition completely inhibited wild type IL-6 activity on these cells. Such an antagonist may be used as a specific inhibitor of IL-6 activity in vivo.
Ehlers
M
M
I. Medical Clinic-Section-Pathophysiology, Mainz University, Germany.
de Hon
F D
FD
Bos
H K
HK
Horsten
U
U
Kurapkat
G
G
van De Leur
H S
HS
Grötzinger
J
J
Wollmer
A
A
Brakenhoff
J P
JP
Rose-John
S
S
D000818:Animals; D015703:Antigens, CD; D001483:Base Sequence; D050822:Cytokine Receptor gp130; D006801:Humans; D015850:Interleukin-6 / Q000737:chemistry / Q000235:genetics*; D008562:Membrane Glycoproteins / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009101:Multiple Myeloma / Q000378:metabolism / Q000473:pathology; D009838:Oligodeoxyribonucleotides; D017354:Point Mutation; D011487:Protein Conformation; D018123:Receptors, Interleukin / Q000037:antagonists & inhibitors*; D019947:Receptors, Interleukin-6; D014407:Tumor Cells, Cultured
D015703:Antigens, CD; C494199:IL6ST protein, human; C494200:Il6st protein, mouse; D015850:Interleukin-6; D008562:Membrane Glycoproteins; D009838:Oligodeoxyribonucleotides; D018123:Receptors, Interleukin; D019947:Receptors, Interleukin-6; D050822:Cytokine Receptor gp130