Leptin receptor (OB-R) oligomerizes with itself but not with its closely related cytokine signal transducer gp130

Leptin (OB) exerts weight-reducing effects in mice. The structure of the receptor for this factor, OB-R, is considerably similar to those of gp130, the common signal transducing receptor component for the interleukin-6 (IL-6) family of cytokines, and leukemia inhibitory factor receptor (LIPR). Since the IL-6 family of cytokines signal through gp130 homodimer or gp130/LIFR heterodimer, we have examined in this study the possible involvement of gp130 and LIPR in leptin signaling through OB-R. Leptin stimulation induces tyrosine phosphorylation of neither gp130 nor LIFR, while LIF stimulation does both. As examined by using two differently epitope-tagged OB-R molecules, the spontaneous homo-oligomerization of OB-R has been elucidated. Ba/F3 cells, which do not express gp130, are non-responsive to leptin and exhibit increased DNA synthesis in response to leptin after transfection of OB-R cDNA alone. OB-R appears to transduce the signal via its homooligomerization without interaction with gp130 or LIFR. (C) 1997 Federation of European Biochemical Societies.