title: Bivalent binding and signaling characteristics of Leridistim, a novel chimeric dual agonist of interleukin-3 and granulocyte colony-stimulating factor receptors.
abstract: Leridistim is a member of a novel family of engineered chimeric cytokines, myelopoietins, that contain agonists of both interleukin-3 (IL-3) receptors (IL-3R) and granulocyte colony-stimulating factor (G-CSF) receptors (G-CSFR). To more clearly understand Leridistim's function at the molecular level, binding to both IL-3R and G-CSFR and subsequent signaling characteristics have been delineated. The affinity of Leridistim for the human G-CSFR was found to be comparable to that of native G-CSF (IC(50) = 0.96 nM and 1.0 nM, respectively). Both Leridistim and G-CSF induced receptor tyrosine phosphorylation to a similar maximal level. Compared with native recombinant human IL-3 (rhIL-3), Leridistim was found to possess higher affinity for the IL-3R alpha chain (IL-3Ralpha) (IC(50) = 85 nM and 162 nM, respectively). However, the increase in Leridistim binding affinity to the functional, high-affinity heterodimeric IL-3Ralphabeta(c) receptor is lower than that observed with rhIL-3 (85 nM and 14 nM vs 162 nM and 3.5 nM, respectively). Leridistim induced tyrosine phosphorylation of beta(c) to a level comparable to native IL-3, and the level of JAK2 tyrosine phosphorylation in cells expressing both IL-3R and G-CSFR was comparable to that observed with IL-3 or G-CSF alone. The ability of Leridistim to interact with IL-3R and G-CSFR simultaneously was demonstrated using surface plasmon resonance analysis. These studies were extended to demonstrate that Leridistim exhibited a higher affinity for the IL-3R on cells that express both the IL-3Ralphabeta(c) and the G-CSFR (IC(50) = 2 nM) compared with cells that contain the IL-3Ralphabeta(c) alone (IC(50) = 14 nM). Leridistim binds to both IL-3R and G-CSFR simultaneously and has been shown to activate both receptors. The bivalent avidity may explain the unique biologic effects and unexpected potency of Leridistim in hematopoietic cells compared with rhIL-3 or G-CSF alone or in combination.
authors: Discovery Research, Pharmacia Corporation, 700 Chesterfield Village Parkway, Chesterfield, MO 63017, USA. joseph.b.monahan@monsanto.com
authors: J B
authors: JB
authors: Monahan
authors: W F
authors: WF
authors: Hood
authors: J K
authors: JK
authors: Welply
authors: J J
authors: JJ
authors: Shieh
authors: J O
authors: JO
authors: Polazzi
authors: X
authors: X
authors: Li
mesh_terms: D000818:Animals; D018952:Antigens, CD34 / Q000032:analysis; D001854:Bone Marrow Cells / Q000276:immunology / Q000378:metabolism; D002460:Cell Line; D006224:Cricetinae; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism; D019281:Dimerization; D004586:Electrophoresis; D016179:Granulocyte Colony-Stimulating Factor / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D007377:Interleukin-3 / Q000235:genetics / Q000378:metabolism*; D053614:Janus Kinase 2; D015470:Leukemia, Myeloid, Acute; D051379:Mice; D008894:Milk Proteins; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins; D016188:Receptors, Granulocyte Colony-Stimulating Factor / Q000819:agonists* / Q000235:genetics / Q000378:metabolism; D016185:Receptors, Interleukin-3 / Q000819:agonists* / Q000235:genetics / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D050799:STAT5 Transcription Factor; D015398:Signal Transduction; D020349:Surface Plasmon Resonance; D015534:Trans-Activators / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D018952:Antigens, CD34; D004268:DNA-Binding Proteins; D007377:Interleukin-3; D008894:Milk Proteins; D011518:Proto-Oncogene Proteins; D016188:Receptors, Granulocyte Colony-Stimulating Factor; D016185:Receptors, Interleukin-3; D011993:Recombinant Fusion Proteins; D011994:Recombinant Proteins; D050799:STAT5 Transcription Factor; D015534:Trans-Activators; D016179:Granulocyte Colony-Stimulating Factor; C400711:leridistim; D019000:Phosphotyrosine; D004247:DNA; D011505:Protein-Tyrosine Kinases; C507924:JAK2 protein, human; C507926:Jak2 protein, mouse; D053614:Janus Kinase 2