Characterization of osteoprotegerin binding to glycosaminoglycans by surface plasmon resonance: role in the interactions with receptor activator of nuclear factor kappaB ligand (RANKL) and RANK.

Osteoprotegerin (OPG) is a decoy receptor for receptor activator of nuclear factor kappaB ligand (RANKL), a key inducer of osteoclastogenesis via its receptor RANK. We previously showed that RANK, RANKL, and OPG are able to form a tertiary complex and that OPG must be also considered as a direct effector of osteoclast functions. As OPG contains a heparin-binding domain, the present study investigated the interactions between OPG and glycosaminoglycans (GAGs) by surface plasmon resonance and their involvement in the OPG functions.

Soluble interleukin-15 receptor alpha (IL-15R alpha)-sushi as a selective and potent agonist of IL-15 action through IL-15R beta/gamma. Hyperagonist IL-15 x IL-15R alpha fusion proteins.

Interleukin-15 (IL-15) is crucial for the generation of multiple lymphocyte subsets (natural killer (NK), NK-T cells, and memory CD8 T cells), and transpresentation of IL-15 by monocytes and dendritic cells has been suggested to be the dominant activating process of these lymphocytes. We have previously shown that a natural soluble form of IL-15R alpha chain corresponding to the entire extracellular domain of IL-15R alpha behaves as a high affinity IL-15 antagonist. In sharp contrast with this finding, we demonstrate in this report that a recombinant, soluble sushi domain of IL-15R alpha, which bears most of the binding affinity for IL-15, behaves as a potent IL-15 agonist by enhancing its binding and biological effects (proliferation and protection from apoptosis) through the IL-15R beta/gamma heterodimer, whereas it does not affect IL-15 binding and function of the tripartite IL-15R alpha/beta/gamma membrane receptor.

Production of recombinant human trimeric CD137L (4-1BBL). Cross-linking is essential to its T cell co-stimulation activity.

The interaction between 4-1BB ligand (CD137L), a member of the tumor necrosis factor superfamily, and its receptor 4-1BB provides a co-stimulatory signal for T lymphocyte proliferation and survival. However, the structure of 4-1BBL has not been thoroughly investigated, and none of the human recombinant 4-1BBL molecules available have been described as capable of co-stimulating T cells. The present work provides a model of the three-dimensional structure of the tumor necrosis factor homology domain of 4-1BBL and describes the production of a recombinant human soluble 4-1BBL whose originality lies in that it contains the whole extracellular tail preceding the tumor necrosis factor homology domain and an AviTag peptide (AviTag-4-1BBL) allowing enzymatic biotinylation and multimerization via streptavidin.

The first alpha helix of Bax plays a necessary role in its ligand-induced activation by the BH3-only proteins Bid and PUMA.

The mechanism by which some BH3-only proteins of the Bcl-2 family directly activate the "multidomain" proapoptotic member Bax is poorly characterized. We report that the first alpha helix (Halpha1) of Bax specifically interacts with the BH3 domains of Bid and PUMA but not with that of Bad. Inhibition of this interaction, by a peptide comprising Halpha1 or by a mutation in this helix, prevents ligand-induced activation of Bax by Bid, PUMA, or their BH3 peptides.

Cellular activity and signaling induced by osteoprotegerin in osteoclasts: involvement of receptor activator of nuclear factor kappaB ligand and MAPK.

Osteoprotegerin (OPG) is a decoy receptor for receptor activator of nuclear factor kappaB ligand (RANKL), an inducer of osteoclastogenesis via its receptor RANK. We recently demonstrated that OPG also exerts a direct effect in osteoclasts by regulating protease expression. Herein, we showed that OPG-induced pro-matrix metalloproteinase-9 activity was abolished by ras/MAPK inhibitors in purified osteoclasts.

Soluble mannose 6-phosphate/insulin-like growth factor II (IGF-II) receptor inhibits interleukin-6-type cytokine-dependent proliferation by neutralization of IGF-II.

The calcium-independent mannose 6-phosphate receptor (CIMPR) is a receptor for multiple ligands, including leukemia inhibitory factor (LIF), an IL-6 type cytokine, and IGF-II. CIMPR targets newly synthesized ligands to lysosomes and induces internalization/degradation of secreted ligands. A natural soluble form of CIMPR (sCIMPR) neutralizes IGF-II mitogenic potency on hepatocytes and fibroblasts.

Characterization of a potent human interleukin-11 agonist.

Human interleukin-11 (hIL-11) is a multi-potential cytokine that is involved in numerous biological activities, such as haematopoiesis, osteoclastogenesis, neurogenesis and female fertility, and also displays anti-inflammatory properties. IL-11 is used clinically to treat chemotherapy-induced thrombocytopenia. Because of its broad spectrum of action, improved IL-11 agonists, as well as IL-11 antagonists, could be of interest for numerous clinical applications.

Selective blockade of CD28 and not CTLA-4 with a single-chain Fv-alpha1-antitrypsin fusion antibody.

B7-1 and B7-2 are costimulatory molecules expressed on antigen-presenting cells. The CD28/B7 costimulation pathway is critical for T-cell activation, proliferation, and Th polarization. Blocking both cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4) and CD28 interactions with a CTLA-4/Ig fusion protein inhibits various immune-mediated processes in vivo, such as allograft rejection and autoimmunity.

Arginine operator binding by heterologous and chimeric ArgR repressors from Escherichia coli and Bacillus stearothermophilus.

Bacillus stearothermophilus ArgR binds efficiently to the Escherichia coli carAB operator, whereas the E. coli repressor binds very poorly to the argCo operator of B. stearothermophilus.

Epitope mapping of four novel CD44 monoclonal antibodies using surface plasmon resonance and soluble CD44.

CD44 is a ubiquitous multistructural and multifunctional cell surface adhesion molecule. The molecular diversity of this glycoprotein is generated by both post-translational modification and the differential use of alternatively spliced exons which play a critical role in determining the exact conformation of the molecule. CD44 isoforms are found in many tissues and in soluble form in plasma.

Identification of the domain in the human interleukin-11 receptor that mediates ligand binding.

The interleukin-11 receptor (IL-11R) belongs to the hematopoietic receptor superfamily. The functional receptor complex comprises IL-11, IL-11R and the signal-transducing subunit gp130. The extracellular part of the IL-11R consists of three domains: an N-terminal immunoglobulin-like domain, D1, and two fibronectin-type III-like (FNIII) domains and D2 and D3.

Monoclonal antibodies against the human interleukin-11 receptor alpha-chain (IL-11Ralpha) and their use in studies of human mononuclear cells.

A panel of 14 hybridoma cell lines secreting monoclonal antibodies against the human interleukin-11 receptor alpha chain (hIL-11Ralpha) was obtained using two different approaches. Two antibodies were raised against peptides of the N- and C-terminal sequences, respectively, of the extracellular part of the hIL-11Ralpha. Another group of 12 antibodies was generated against a hybrid protein consisting of the extracellular part of the hIL-11Ralpha fused to mature full-length human IL-2.

Mannose 6-Phosphate/Insulin-like growth factor II receptor mediates internalization and degradation of leukemia inhibitory factor but not signal transduction.

Leukemia inhibitory factor (LIF) is a multifunctional cytokine belonging to the interleukin-6 subfamily of helical cytokines, all of which use the glycoprotein (gp) 130 subunit for signal transduction. The specific receptor for LIF, gp190, binds this cytokine with low affinity and is also required for signal transduction. We have recently reported that glycosylated LIF produced by transfected Chinese hamster ovary cells also binds to a lectin-like receptor, mannose 6-phosphate/insulin-like growth factor II receptor (Man-6-P/IGFII-R) (Blanchard, F.

Characterization of two monoclonal antibodies against porcine VCAM-1.

Immunization of mice with TNF alpha-activated porcine endothelial cells led to the characterization of two monoclonal antibodies (MAbs), 5F3 and 8A7, specific for porcine VCAM-1. Upon flow cytometry, both antibodies increasingly labeled endothelial cells according to their degree of activation. They bound a band of MW 80 kDa on Western blots of endothelial cells, which is the apparent molecular weight of porcine VCAM-1.

The mannose 6-phosphate/insulin-like growth factor II receptor is a nanomolar affinity receptor for glycosylated human leukemia inhibitory factor.

Comparison of the binding properties of non-glycosylated, glycosylated human leukemia inhibitory factor (LIF) and monoclonal antibodies (mAbs) directed at gp190/LIF-receptor beta subunit showed that most of the low affinity (nanomolar) receptors expressed by a variety of cell lines are not due to gp190. These receptors bind glycosylated LIF produced in Chinese hamster ovary cells (CHO LIF) (Kd = 6.9 nM) but not Escherichia coli-derived LIF or CHO LIF treated with endoglycosidase F.