Functional distinction of two regions of human interleukin 6 important for signal transduction via gp130.
Mutagenesis of a region of human interleukin (IL)-6 which is important for triggering signal transduction via the IL-6 receptor beta-chain (gp130) has lead to the isolation of a variant of human IL-6 (IL-6.Q160E/T163P), which could antagonize the biological activity of wild type IL-6 on the human EBV transformed B cell line CESS and the human hepatoma cell line HepG2. Surprisingly this antagonistic IL-6 variant had an agonistic effect on the human myeloma cell line XG-1, albeit at a 1000-fold higher concentration than wild type IL-6. This residual activity of the mutant arose from triggering gp130, because it could be inhibited by a gp130 specific mAb. Extensive mutagenesis of residues between Q153 and H165 of human IL-6, a region which is partly homologous in cytokines which also signal via gp130 (oncostatin M, ciliary neurotrophic factor, leukaemia inhibitory factor, IL-11), did result in the isolation of a second antagonist for IL-6 activity on CESS and HepG2 cells. However on XG-1 cells this variant was active as well. These results suggest that (an) additional region(s) of the IL-6 molecule might be involved in gp130 triggering. Recently we indeed found that residues Lys42-Ala57 are also important for gp130 triggering. Inhibition experiments with neutralizing IL-6R alpha-chain specific mAb show that this region can be functionally separated from the Q153-H165 region. These findings have important implications for the development of receptor antagonists of IL-6 and IL-6 family members.
de Hon
F D
FD
Department of Autoimmune Diseases, Central Laboratory of the Netherlands Red Cross Blood Transfusion Service, Amsterdam.
ten Boekel
E
E
Herrman
J
J
Clement
C
C
Ehlers
M
M
Taga
T
T
Yasukawa
K
K
Ohsugi
Y
Y
Kishimoto
T
T
Rose-John
S
S
D000409:Alanine / Q000737:chemistry; D000911:Antibodies, Monoclonal; D015703:Antigens, CD / Q000737:chemistry*; D015723:Gene Library; D005820:Genetic Testing; D005973:Glutamine / Q000737:chemistry; D006639:Histidine / Q000737:chemistry; D006801:Humans; D015850:Interleukin-6 / Q000737:chemistry / Q000235:genetics*; D009101:Multiple Myeloma / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D017434:Protein Structure, Tertiary; D018123:Receptors, Interleukin / Q000737:chemistry*; D019947:Receptors, Interleukin-6; D015398:Signal Transduction / Q000187:drug effects*; D013912:Threonine / Q000737:chemistry; D014407:Tumor Cells, Cultured
D000911:Antibodies, Monoclonal; D015703:Antigens, CD; D015850:Interleukin-6; D018123:Receptors, Interleukin; D019947:Receptors, Interleukin-6; D005973:Glutamine; D013912:Threonine; D006639:Histidine; D000409:Alanine