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Expression levels of gp130 in bone marrow stromal cells determine the magnitude of osteoclastogenic signals generated by IL‐6‐type cytokines
Author(s) -
O'Brien Charles A.,
Lin SongChang,
Bellido Teresita,
Manolagas Stavros C.
Publication year - 2000
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/1097-4644(20001215)79:4<532::aid-jcb20>3.0.co;2-u
Subject(s) - oncostatin m , glycoprotein 130 , stromal cell , osteoclast , cytokine , chemistry , rankl , medicine , rank ligand , microbiology and biotechnology , endocrinology , interleukin 6 , receptor , cell culture , biology , activator (genetics) , cancer research , immunology , genetics
Interleukin‐6 (IL‐6)‐type cytokines stimulate osteoclast formation by activating the glycoprotein 130 (gp130) receptor subunit on stromal/osteoblastic cells, which in turn leads to signal transducer and activator of transcription 3 (STAT3)‐mediated expression of receptor activator of NF‐κB ligand (RANKL). Based on evidence that gp130 expression is regulated by a variety of cytokines and hormones, we have determined here whether changes in gp130 levels directly contribute to the magnitude of the osteoclastogenic stimulus delivered by IL‐6‐type cytokines. To accomplish this, gp130 protein levels were modulated using a tetracycline‐regulated expression system in a stromal/osteoblastic cell line, UAMS‐32, which supports osteoclast formation. Removal of doxycycline from the culture medium elevated gp130 expression and increased the responsiveness of a STAT‐responsive promoter‐luciferase construct to IL‐6 complexed with its soluble receptor (IL‐6+sIL‐6R), but diminished the responsiveness to oncostatin M (OSM). IL‐6+sIL‐6R‐stimulated osteoclast formation was greater when osteoclast precursors were cocultured with the cells expressing elevated gp130 levels than when cells expressing low gp130 levels were used. However, increased gp130 levels reduced OSM‐stimulated osteoclast formation. These results establish that the level of gp130 in stromal/osteoblastic cells directly modulates the magnitude of the osteoclastogenic response to IL‐6‐type cytokines such that an increase in gp130 increases the cellular responsiveness to IL‐6+sIL‐6R but reduces responsiveness to OSM. J. Cell. Biochem. 79:532–541, 2000. © 2000 Wiley‐Liss, Inc.