Oncostatin M binds directly to gp130 and behaves as interleukin-6 antagonist on a cell line expressing gp130 but lacking functional oncostatin M receptors

G. Paonessa,G. Ciliberto,P. Delmastro,C. Toniatti,A.L. Salvati,E. Sporeno,R. Graziani

doi:10.1016/s0021-9258(19)78081-8

Abstract

Oncostatin M (OM) and interleukin 6 (IL-6) are functionally related cytokines, which trigger similar biological responses because they share gp130 as a common signal transducing transmembrane receptor. While IL-6 recruits gp130 only upon binding to its specific receptor subunit (IL-6R alpha), reconstitution and cross-linking experiments on cell membranes suggest that OM can directly interact with gp130 and that this interaction is necessary but not sufficient to stimulate cells. However, the issue of the direct binding between gp130 and OM, in the absence of any additional membrane component, remained essentially unclarified. In this paper we show that, uniquely among the family of cytokines that transduce through gp130, OM directly binds in vitro with a 10(-8) M affinity sgp130, a soluble form of gp130. Moreover, titration of sgp130 with OM inhibits the formation of a ternary complex comprising IL-6, sIL-6R alpha, and sgp130. These in vitro properties of OM are consistent with the additional finding that on human hepatoma Hep3B cells, which express gp130 but not functional OM receptors, OM does not mimic IL-6 activity, but rather behaves, at high doses, as an IL-6 antagonist.

Highlights

OncostatinM (OM) and interleukin6 (IL-6)are func- quently, the individual cytokine-receptor complexes all associtionally related cytokines, which trisgigmeirlar biologi- ate with the samep signal-transducing transmembraneglycocal responses because they share gp130 as acommon protein, namely gp130
Family of cytokines has been recently clarified by the observation that they sharea receptor component involved in signal transduction across the cell membrane [5,6,7]
Since murine IL-6 is not able to bind to the human receptor (281, no sgpl30 was immunoprecipitated in this case (Fig. 1, lane 4 )

Summary

Introduction

OncostatinM (OM) and interleukin6 (IL-6)are func- quently, the individual cytokine-receptor complexes all associtionally related cytokines, which trisgigmeirlar biologi- ate with the samep signal-transducing transmembraneglycocal responses because they share gp130 as acommon protein, namely gp130. The specific radioactivity was determined to be 2 x 1015 concentrations of methotrexate were performed, and one clone, cwmphedliacmnhmowmoaals.ctIeeollsdstie(nd2a2tfio)o.rnFitdosirdabndioilstiptylaaftcfoeecmitnehtnhitbeibtbitinohdleoingggircoaewlxptphreoorpfimeAret3in7et5ss,ohftuhmOeMaan,pprona-sasmesesdeCdsbGyhqlOu,awnthiitcahtievxepWreesssetesrtnhbelohttiignhgesoltnevtehlse of sgpl30 as conditioned priate amount of purified sgpl30 (as determined in preliminary titra- medium (not shown),wasfinally selected (for details,see tion experiments) was incubated PinBS, 1% BSA,3 nm imidazole with "Experimental Procedures").

Objectives

Results

Conclusion