1
|
|
2
|
Kish WS, Sachi H, Naik AD, Roach MK, Bobay BG, Blackburn RK, Menegatti S, Carbonell RG. Design, selection, and development of cyclic peptide ligands for human erythropoietin. J Chromatogr A 2017; 1500:105-120. [DOI: 10.1016/j.chroma.2017.04.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Revised: 03/28/2017] [Accepted: 04/10/2017] [Indexed: 11/26/2022]
|
3
|
Fox NE, Lim J, Chen R, Geddis AE. F104S c-Mpl responds to a transmembrane domain-binding thrombopoietin receptor agonist: proof of concept that selected receptor mutations in congenital amegakaryocytic thrombocytopenia can be stimulated with alternative thrombopoietic agents. Exp Hematol 2010; 38:384-91. [PMID: 20188141 DOI: 10.1016/j.exphem.2010.02.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2009] [Revised: 02/10/2010] [Accepted: 02/16/2010] [Indexed: 12/22/2022]
Abstract
OBJECTIVE To determine whether specific c-Mpl mutations might respond to thrombopoietin receptor agonists. MATERIALS AND METHODS We created cell line models of type II c-Mpl mutations identified in congenital amegakaryocytic thrombocytopenia. We selected F104S c-Mpl for further study because it exhibited surface expression of the receptor. We measured proliferation of cell lines expressing wild-type or F104S c-Mpl in response to thrombopoietin receptor agonists targeting the extracellular (m-AMP4) or transmembrane (LGD-4665) domains of the receptor by 1-methyltetrazole-5-thiol assay. We measured thrombopoietin binding to the mutant receptor using an in vitro thrombopoietin uptake assay and identified F104 as a potentially critical residue for the interaction between the receptor and its ligand by aligning thrombopoietin and erythropoietin receptors from multiple species. RESULTS Cells expressing F104S c-Mpl proliferated in response to LGD-4665, but not thrombopoietin or m-AMP4. Compared to thrombopoietin, LGD-4665 stimulates signaling with delayed kinetics in both wild-type and F104S c-Mpl-expressing cells. Although F104S c-Mpl is expressed on the cell surface in our BaF3 cell line model, the mutant receptor does not bind thrombopoietin. Comparison to the erythropoietin receptor suggests that F104 engages in hydrogen-bonding interactions that are critical for binding to thrombopoietin. CONCLUSIONS These findings suggest that a small subset of patients with congenital amegakaryocytic thrombocytopenia might respond to treatment with thrombopoietin receptor agonists, but that responsiveness will depend on the type of mutation and agonist used. We postulate that F104 is critical for thrombopoietin binding. The kinetics of signaling in response to a transmembrane domain-binding agonist are delayed in comparison to thrombopoietin.
Collapse
Affiliation(s)
- Norma E Fox
- Pediatric Hematology-Oncology, University of California, San Diego, La Jolla, Calif. 92017, USA
| | | | | | | |
Collapse
|
4
|
Abstract
Erythropoietin (EPO), a glycoprotein hormone, stimulates the growth of red blood cells and as a consequence it increases tissue oxygenation. This performance enhancing effect is responsible for the ban of erythropioetin in sports since 1990. Especially its recombinant synthesis led to the abuse of this hormone, predominatly in endurance sports. The analytical differentiation of endogenously produced erythropoietin from its recombinant counterpart by using isoelectric focusing and double blotting is a milestone in the detection of doping with recombinant erythropoietin. However, various analogous of the initial recombinant products, not always easily detectable by the standard IEF-method, necessitate the development of analytical alternatives for the detection of EPO doping. The following chapter summarizes its mode of action, the various forms of recombinant erythropoietin, the main analytical procedures and strategies for the detection of EPO doping as well as a typical case report.
Collapse
Affiliation(s)
- Christian Reichel
- Austrian Research Centers GmbH - ARC, Doping Control Laboratory, A-2444, Seibersdorf, Austria.
| | | |
Collapse
|
5
|
Li K, Menon MP, Karur VG, Hegde S, Wojchowski DM. Attenuated signaling by a phosphotyrosine-null Epo receptor form in primary erythroid progenitor cells. Blood 2003; 102:3147-53. [PMID: 12869513 DOI: 10.1182/blood-2003-01-0078] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Signals provided by the erythropoieitin receptor (EpoR) are required for erythroid development beyond the erythroid colony-forming unit (CFU-e) stage and are propagated via the EpoR-tethered Janus kinase, JAK2. JAK2 functions, in part, to phosphorylate 8 conserved EpoR phosphotyrosine (PY) sites for the binding of a diverse set of signaling factors. However, recent studies in transgenic and knock-in mice have demonstrated substantial bioactivity for PY-null EpoR forms. Presently, the activities of a PY-null EpoR-HM form in primary progenitor cells from knock-in mice were further assessed using optimized Epo dose-dependent proliferation, survival, and differentiation assays. As compared with the wild-type (wt)-EpoR, EpoR-HM activity was compromised several-fold in each context when Epo was limited to physiologic concentrations. Possible compensatory increases in serum growth factor levels also were investigated, and as assayed using embryonic stem (ES) cell-derived erythroid G1E2 cells, activities in serum from EpoR-HM mice were substantially elevated. In addition, when challenged with phenylhydrazine-induced anemia, EpoR-HM mice failed to respond with efficient splenic stress erythropoiesis. Thus, the function of this JAK2-coupled but minimal PY-null EpoR-HM form appears to be attenuated in several contexts and to be assisted in vivo by compensatory mechanisms. Roles normally played by EpoR PY sites and distal domains therefore should receive continued attention.
Collapse
Affiliation(s)
- Ke Li
- Immunobiology Program and Department of Veterinary Science, The Pennsylvania State University, University Park, PA 16802, USA
| | | | | | | | | |
Collapse
|
6
|
Gaudard A, Varlet-Marie E, Bressolle F, Audran M. Drugs for increasing oxygen and their potential use in doping: a review. Sports Med 2003; 33:187-212. [PMID: 12656640 DOI: 10.2165/00007256-200333030-00003] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Blood oxygenation is a fundamental factor in optimising muscular activity. Enhancement of oxygen delivery to tissues is associated with a substantial improvement in athletic performance, particularly in endurance sports. Progress in medical research has led to the identification of new chemicals for the treatment of severe anaemia. Effective and promising molecules have been created and sometimes used for doping purposes. The aim of this review is to present methods, and drugs, known to be (or that might be) used by athletes to increase oxygen transport in an attempt to improve endurance capacity. These methods and drugs include: (i) blood transfusion; (ii) endogenous stimulation of red blood cell production at altitude, or using hypoxic rooms, erythropoietins (EPOs), EPO gene therapy or EPO mimetics; (iii) allosteric effectors of haemoglobin; and (iv) blood substitutes such as modified haemoglobin solutions and perfluorochemicals. Often, new chemicals are used before safety tests have been completed and athletes are taking great health risks. Such new chemicals have also created the need for new instrumental strategies in doping control laboratories, but not all of these chemicals are detectable. Further progress in analytical research is necessary.
Collapse
Affiliation(s)
- Aurelie Gaudard
- Clinical Pharmacokinetic Laboratory, Faculty of Pharmacy, University Montpellier I, Montpellier, France
| | | | | | | |
Collapse
|
7
|
Biazzo DE, Motamedi H, Mark DF, Qureshi SA. A high-throughput assay to identify compounds that can induce dimerization of the erythropoietin receptor. Anal Biochem 2000; 278:39-45. [PMID: 10640351 DOI: 10.1006/abio.1999.4408] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Erythropoietin induces dimerization of the erythropoietin receptor on the surface of erythroid progenitor cells, promoting the differentiation of these cells into mature red blood cells. To facilitate screening of large chemical collections for identification of compounds that can dimerize erythropoietin receptor, we have developed a novel, high-throughput in vitro assay to detect compounds that can cause dimerization of the erythropoietin receptor in solution. To develop this assay, amino acid sequences corresponding to the extracellular domain of erythropoietin receptor were expressed in Escherichia coli as erythropoietin-binding protein (rEBP). A modified version of this protein ((33)P-rEBP) containing a protein kinase A substrate site incorporated into the rEBP was also expressed in E. coli and labeled in vitro using protein kinase A and ¿gamma-(33)PATP. An erythropoietin mimetic peptide (EMP-1), that induces dimerization of rEBP in solution was used to demonstrate dimerization of (33)P-rEBP and rEBP in a 96-well microtiter plate format. EMP-1 induced dimerization of rEBP in this assay with an EC(50) of approximately 245 nM and had a maximal effect at 0.5-2 microM and required the presence of rEBP immobilized on the plate capable of binding EMP-1. EMP-1-induced dimerization of (33)P-rEBP and rEBP was reversed by excess unlabeled rEBP and was not masked by complex mixtures such as whole cell fungal extracts. These data demonstrate the ability of (33)P-rEBP to dimerize with rEBP in vitro in a format that is fully compatible with high-throughput screening.
Collapse
Affiliation(s)
- D E Biazzo
- Merck Research Laboratories, Rahway, New Jersey 07065-0900, USA
| | | | | | | |
Collapse
|
8
|
Middleton SA, Barbone FP, Johnson DL, Thurmond RL, You Y, McMahon FJ, Jin R, Livnah O, Tullai J, Farrell FX, Goldsmith MA, Wilson IA, Jolliffe LK. Shared and unique determinants of the erythropoietin (EPO) receptor are important for binding EPO and EPO mimetic peptide. J Biol Chem 1999; 274:14163-9. [PMID: 10318834 DOI: 10.1074/jbc.274.20.14163] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have shown previously that Phe93 in the extracellular domain of the erythropoietin (EPO) receptor (EPOR) is crucial for binding EPO. Substitution of Phe93 with alanine resulted in a dramatic decrease in EPO binding to the Escherichia coli-expressed extracellular domain of the EPOR (EPO-binding protein or EBP) and no detectable binding to full-length mutant receptor expressed in COS cells. Remarkably, Phe93 forms extensive contacts with a peptide ligand in the crystal structure of the EBP bound to an EPO-mimetic peptide (EMP1), suggesting that Phe93 is also important for EMP1 binding. We used alanine substitution of EBP residues that contact EMP1 in the crystal structure to investigate the function of these residues in both EMP1 and EPO binding. The three largest hydrophobic contacts at Phe93, Met150, and Phe205 and a hydrogen bonding interaction at Thr151 were examined. Our results indicate that Phe93 and Phe205 are important for both EPO and EMP1 binding, Met150 is not important for EPO binding but is critical for EMP1 binding, and Thr151 is not important for binding either ligand. Thus, Phe93 and Phe205 are important binding determinants for both EPO and EMP1, even though these ligands share no sequence or structural homology, suggesting that these residues may represent a minimum epitope on the EPOR for productive ligand binding.
Collapse
Affiliation(s)
- S A Middleton
- R. W. Johnson Pharmaceutical Research Institute, Raritan, New Jersey 08869, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
9
|
Hendrix DK, Klein TE, Kuntz ID, Klien TE. Macromolecular docking of a three-body system: the recognition of human growth hormone by its receptor. Protein Sci 1999; 8:1010-22. [PMID: 10338012 PMCID: PMC2144328 DOI: 10.1110/ps.8.5.1010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Human growth hormone (hGH) binds to its receptor (hGHr) in a three-body interaction: one molecule of the hormone and two identical monomers of the receptor form a trimer. Curiously, the hormone-receptor interactions in the trimer are not equivalent and the formation of the complex occurs in a specific kinetic order (Cunningham BC, Ultsch M, De Vos AM, Mulkerrin MG, Clauser KR, Wells JA, 1991, Science 254:821-825). In this paper, we model the recognition of hGH to the hGHr using shape complementarity of the three-dimensional structures and macromolecular docking to explore possible binding modes between the receptor and hormone. The method, reported previously (Hendrix DK, Kuntz ID, 1998, Pacific symposium on biocomputing 1998, pp 1234-1244), is based upon matching complementary-shaped strategic sites on the molecular surface. We modify the procedure to examine three-body systems. We find that the order of binding seen experimentally is also essential to our model. We explore the use of mutational data available for hGH to guide our model. In addition to docking hGH to the hGHr, we further test our methodology by successfully reproducing 16 macromolecular complexes from X-ray crystal structures, including enzyme-inhibitor, antibody-antigen, protein dimer, and protein-DNA complexes.
Collapse
Affiliation(s)
- D K Hendrix
- Department of Pharmaceutical Chemistry, University of California, San Francisco, 94143-0446, USA
| | | | | | | |
Collapse
|
10
|
Livnah O, Stura EA, Middleton SA, Johnson DL, Jolliffe LK, Wilson IA. Crystallographic evidence for preformed dimers of erythropoietin receptor before ligand activation. Science 1999; 283:987-90. [PMID: 9974392 DOI: 10.1126/science.283.5404.987] [Citation(s) in RCA: 460] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Erythropoietin receptor (EPOR) is thought to be activated by ligand-induced homodimerization. However, structures of agonist and antagonist peptide complexes of EPOR, as well as an EPO-EPOR complex, have shown that the actual dimer configuration is critical for the biological response and signal efficiency. The crystal structure of the extracellular domain of EPOR in its unliganded form at 2.4 angstrom resolution has revealed a dimer in which the individual membrane-spanning and intracellular domains would be too far apart to permit phosphorylation by JAK2. This unliganded EPOR dimer is formed from self-association of the same key binding site residues that interact with EPO-mimetic peptide and EPO ligands. This model for a preformed dimer on the cell surface provides insights into the organization, activation, and plasticity of recognition of hematopoietic cell surface receptors.
Collapse
Affiliation(s)
- O Livnah
- Department of Molecular Biology and Skaggs Institute of Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037, USA
| | | | | | | | | | | |
Collapse
|
11
|
Syed RS, Reid SW, Li C, Cheetham JC, Aoki KH, Liu B, Zhan H, Osslund TD, Chirino AJ, Zhang J, Finer-Moore J, Elliott S, Sitney K, Katz BA, Matthews DJ, Wendoloski JJ, Egrie J, Stroud RM. Efficiency of signalling through cytokine receptors depends critically on receptor orientation. Nature 1998; 395:511-6. [PMID: 9774108 DOI: 10.1038/26773] [Citation(s) in RCA: 418] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Human erythropoietin is a haematopoietic cytokine required for the differentiation and proliferation of precursor cells into red blood cells. It activates cells by binding and orientating two cell-surface erythropoietin receptors (EPORs) which trigger an intracellular phosphorylation cascade. The half-maximal response in a cellular proliferation assay is evoked at an erythropoietin concentration of 10 pM, 10(-2) of its Kd value for erythropoietin-EPOR binding site 1 (Kd approximately equal to nM), and 10(-5) of the Kd for erythropoietin-EPOR binding site 2 (Kd approximately equal to 1 microM). Overall half-maximal binding (IC50) of cell-surface receptors is produced with approximately 0.18 nM erythropoietin, indicating that only approximately 6% of the receptors would be bound in the presence of 10 pM erythropoietin. Other effective erythropoietin-mimetic ligands that dimerize receptors can evoke the same cellular responses but much less efficiently, requiring concentrations close to their Kd values (approximately 0.1 microM). The crystal structure of erythropoietin complexed to the extracellular ligand-binding domains of the erythropoietin receptor, determined at 1.9 A from two crystal forms, shows that erythropoietin imposes a unique 120 degrees angular relationship and orientation that is responsible for optimal signalling through intracellular kinase pathways.
Collapse
Affiliation(s)
- R S Syed
- Amgen Inc., Thousand Oaks, California 91320-1789, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
12
|
Barth HG, Boyes BE, Jackson C. Size Exclusion Chromatography and Related Separation Techniques. Anal Chem 1998. [DOI: 10.1021/a1980015t] [Citation(s) in RCA: 122] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Howard G. Barth
- Central Research and Development, DuPont Company, Experimental Station, P.O. Box 80228, Wilmington, Delaware 19880-0228, Little Falls Analytical DivisionNewport, Hewlett-Packard Company, 538 First State Boulevard, Newport, Delaware 19804, and Marshall Laboratory, DuPont Automative Products, 3401 Grays Ferry Avenue, Philadelphia, Pennsylvania 19146
| | - Barry E. Boyes
- Central Research and Development, DuPont Company, Experimental Station, P.O. Box 80228, Wilmington, Delaware 19880-0228, Little Falls Analytical DivisionNewport, Hewlett-Packard Company, 538 First State Boulevard, Newport, Delaware 19804, and Marshall Laboratory, DuPont Automative Products, 3401 Grays Ferry Avenue, Philadelphia, Pennsylvania 19146
| | - Christian Jackson
- Central Research and Development, DuPont Company, Experimental Station, P.O. Box 80228, Wilmington, Delaware 19880-0228, Little Falls Analytical DivisionNewport, Hewlett-Packard Company, 538 First State Boulevard, Newport, Delaware 19804, and Marshall Laboratory, DuPont Automative Products, 3401 Grays Ferry Avenue, Philadelphia, Pennsylvania 19146
| |
Collapse
|
13
|
Johnson DL, Farrell FX, Barbone FP, McMahon FJ, Tullai J, Kroon D, Freedy J, Zivin RA, Mulcahy LS, Jolliffe LK. Amino-terminal dimerization of an erythropoietin mimetic peptide results in increased erythropoietic activity. CHEMISTRY & BIOLOGY 1997; 4:939-50. [PMID: 9427659 DOI: 10.1016/s1074-5521(97)90302-1] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
BACKGROUND Erythropoietin (EPO), the hormone involved in red blood cell production, activates its receptor by binding to the receptor's extracellular domain and presumably dimerizing two receptor monomers to initiate signal transduction. EPO-mimetic peptides, such as EMP1, also bind and activate the receptor by dimerization. These mimetic peptides are not as potent as EPO, however. The crystal structure of the EPO receptor (EBP) bound to EMP1 reveals the formation of a complex consisting of two peptides bound to two receptors, so we sought to improve the biological activity of EPO-mimetic peptides by constructing covalent dimers of EMP1 and other peptide mimetics linked by polyethylene glycol (PEG). RESULTS The potency of the PEG-dimerized EPO peptide mimetics both in vitro and in vivo was improved up to 1,000-fold compared to the corresponding peptide monomers. The dimers were constructed using peptide monomers which have only one reactive amine per molecule, allowing us to conclude that the increase in potency can be attributed to a structure in which two peptides are linked through their respective amino termini to the difunctional PEG molecule. In addition, an inactive peptide was converted into a weak agonist by PEG-induced dimerization. CONCLUSIONS The potency of previously isolated peptides that are modest agonists of the EPO receptor was dramatically increased by PEG-induced dimerization. The EPO receptor is thought to be dimerized during activation, so our results are consistent with the proposed 2:2 receptor : peptide stoichiometry. The conversion of an inactive peptide into an agonist further supports the idea that dimerization can mediate receptor activation.
Collapse
Affiliation(s)
- D L Johnson
- Drug Discovery Research, R.W. Johnson Pharmaceutical Research Institute, Route 202, Box 300, Raritan, NJ 08869, USA. . com
| | | | | | | | | | | | | | | | | | | |
Collapse
|