An Antagonist for the Leukemia Inhibitory Factor Receptor Inhibits Leukemia Inhibitory Factor, Cardiotrophin-1, Ciliary Neurotrophic Factor, and Oncostatin M

Abstract

The leukemia inhibitory factor receptor (LIF-R) is activated not only by LIF, but also by cardiotrophin-1, ciliary neurotrophic factor with its receptor, and oncostatin M (OSM). Each of these cytokines induces the hetero-oligomerization of LIF-R with gp130, a signaltransducing subunit shared with interleukin-6 and interleukin-11. The introduction of mutations into human LIF that reduced the affinity for gp130 while retaining affinity for LIF-R has generated antagonists for LIF. In the current study, a LIF antagonist that was free of detectable agonistic activity was tested for antagonism against the family of LIF-R ligands. On cells that express LIF-R and gp130, all LIF-R ligands were antagonized. On cells that also express OSM receptor, OSM was not antagonized, demonstrating that the antagonist is specific for LIF-R. Ligand-triggered tyrosine phosphorylation of both LIF-R and gp130 was blocked by the antagonist. The antagonist is therefore likely to work by preventing receptor oligomerization.Functional overlap among cytokines often derives from shared receptor components. Interleukin-6 (IL-6), 1 IL-11, leukemia inhibitory factor (LIF), cardiotrophin-1 (CT-1), ciliary neurotrophic factor (CNTF), and OSM (oncostatin M) have biological activities in common, and all require gp130 as a signal-transducing subunit (for review see Ref. 1). LIF (2-6), CT-1 (7), CNTF (8,9), and OSM (6, 10, 11) activate gp130 in complexes with LIF receptor (LIF-R). LIF-R is a transmembrane signaling subunit that is structurally related to gp130 and belongs to the same hematopoietin receptor family (4). Ligand binding drives the heterodimerization of LIF-R and gp130, which results in inter alia activation and tyrosine phosphorylation of the Jak-Tyk cytoplasmic tyrosine kinases (12,13). The Jaks in turn phosphorylate tyrosine residues in the cytoplasmic domains of both LIF-R and gp130 (8), allowing the recruitment of substrates with Src homology 2 domains including STAT3 and protein tyrosine phosphatase PTP1D (14 -17) (for review see Refs. 18 and 19). CNTF weakly activates LIF-R-gp130, becoming a potent agonist once first bound to a nonsignal-transducing subunit, CNTFR␣. In addition to LIF-Rgp130, OSM also activates a receptor complex unique to OSM made up of . OSM-R has recently been identified as a transmembrane signaling subunit related to . Thus, LIF-R participates in a subset of gp130-mediated responses that includes all known LIF, CT-1, and CNTF responses, as well as some responses to OSM.LIF-R is moderately expressed in testis, eye, skeletal muscle, ovary, uterus, thymus, brain, and fat and is highly expressed in liver and placenta (21). Activation of LIF-R-gp130 complexes regulates the differentiation and proliferation of a variety of cell lines as well as influencing the behavior of cultured neurons, hepatocytes, and adipocytes (for review see Ref. 22). Gene knockout experiments have demonstrated roles for LIF-R in development. LIF-RϪ/Ϫ and CNTFR␣Ϫ/Ϫ mice show a substantial loss of motor neurons (23,24). LIF-RϪ/Ϫ mice have also be...

Mutations in the Immunoglobulin-like Domain of gp190, the Leukemia Inhibitory Factor (LIF) Receptor, Increase or Decrease Its Affinity for LIF

“…Mutations of cytokines have been made that either enhanced their affinity for a low affinity binding receptor, or impaired their binding to the high affinity transducing chain, providing superagonists or antagonists, respectively (33)(34)(35). Here for the first time, we bring evidence that the ability to bind a cytokine can also be improved by mutating a very limited number of residues in the receptor sequence.…”

Leukemia Inhibitory Factor, Interleukin 6, and Other Cytokines Using the GP130 Transducing Receptor: Roles in Inflammation and Injury

“…To circumvent this problem, these cytokines may be best applied or directed locally, as with viral vectors [159]. The pro-inflammatory properties of this family can be counteracted using dominant negative approaches, such as cytokines that bind receptors but confer no signal [160][161][162][163].…”

Box 2 Region of the Oncostatin M Receptor Determines Specificity for Recruitment of Janus Kinases and STAT5 Activation

“…A 30-min preincubation with the pharmacological inhibitor AG490 (Calbiochem, Darmstadt, Germany) was used as indicated to inhibit activation of JAK2. HDFs were preincubated with LIF-05 (kindly provided by Prof. Dr. J. Heath, University of Birmingham, Birmingham, UK) to inhibit signal transduction via the LIFR (34). Immediately after stimulation, the cells were lysed in Triton lysis buffer (20 mM Tris, pH 7.5, 150 mM NaCl, 1% Triton X-100, 1 mM EDTA, 10 mM NaF, 1 mM Na 3 VO 4 , 1 mM phenylmethylsulfonyl fluoride, 3 g/ml pepstatin, 5 g/ml aprotinin, and 5 g/ml leupeptin) as described previously (25).…”