Characterization of novel non-peptide thrombopoietin mimetics, their species specificity and the activation mechanism of the thrombopoietin receptor.
A series of non-peptide small compounds discovered to be thrombopoietin receptor agonists showed species specificity to humans. Compound I could induce megakaryocyte lineage from human bone marrow cells, but not from mouse, guinea pig or cynomolgus monkey bone marrow cells. To elucidate the mechanism, we identified the pivotal amino acid residue for the receptor activation by compound I by taking advantage of its species specificity. The response of compound I to three human/mouse chimeric receptors indicated the importance of the transmembrane domain. Comparison of amino acid sequences of the transmembrane domain of the thrombopoietin receptor between human and three animal species led us to hypothesize that histidine 499 is necessary for the reactivity to the thrombopoietin mimetics. We verified the hypothesis using two mutant receptors: the human thrombopoietin receptor mutant His499Leu and the mouse thrombopoietin receptor mutant Leu490His. These results should be helpful for structure-activity relationship studies and conducting in vivo studies of thrombopoietin mimetics.
Yamane
Noriko
N
Discovery Research Laboratories, Shionogi & Co., Ltd., 1-1, Futaba-cho 3-chome, Toyonaka-shi, Osaka 561-0825, Japan. noriko.yamane@shionogi.co.jp
Tanaka
Yoshikazu
Y
Ohyabu
Naoki
N
Yamane
Shoji
S
Maekawa
Kazuhiko
K
Ishizaki
Jun
J
Suzuki
Ryuji
R
Itoh
Tsunetoshi
T
Takemoto
Hiroshi
H
D000595:Amino Acid Sequence; D000818:Animals; D018952:Antigens, CD34 / Q000378:metabolism; D001711:Biotransformation / Q000187:drug effects; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D006168:Guinea Pigs; D006801:Humans; D007202:Indicators and Reagents; D008252:Macaca fascicularis; D008533:Megakaryocytes / Q000187:drug effects; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D050506:Mutant Chimeric Proteins / Q000378:metabolism; D009154:Mutation / Q000502:physiology; D010957:Plasmids / Q000235:genetics; D053628:Receptors, Thrombopoietin / Q000187:drug effects* / Q000235:genetics; D013045:Species Specificity; D013926:Thrombopoietin / Q000494:pharmacology*; D014410:Tumor Stem Cell Assay
D018952:Antigens, CD34; D007202:Indicators and Reagents; D050506:Mutant Chimeric Proteins; D053628:Receptors, Thrombopoietin; D013926:Thrombopoietin