Cloning and expression of murine thrombopoietin cDNA and stimulation of platelet production in vivo.
The major regulator of circulating platelet levels is believed to be a cytokine termed thrombopoietin. It is thought to be a lineage-specific cytokine affecting the proliferation and maturation of committed cells resulting in the production of megakaryocytes and platelets. Despite considerable efforts by a number of laboratories, the unequivocal identification of thrombopoietin has proven elusive. Here we report the functional cloning of a murine complementary DNA encoding a ligand for the receptor encoded by the c-mpl proto-oncogene (c-Mpl). The encoded polypeptide has a predicted molecular mass of 35,000 (M(r) 35K). The protein has a novel two-domain structure with an amino-terminal domain homologous with erythropoietin and a carboxy-terminal domain rich in serine, threonine and proline residues and containing seven potential N-linked glycosylation sites. Intraperitoneal injections of mice with recombinant protein increase circulating platelet levels by greater than fourfold after 7 days. These results along with those presented in the accompanying report strongly suggest that the ligand for c-Mpl is thrombopoietin.
Lok
S
S
ZymoGenetics Corporation, Seattle, Washington 98105.
Kaushansky
K
K
Holly
R D
RD
Kuijper
J L
JL
Lofton-Day
C E
CE
Oort
P J
PJ
Grant
F J
FJ
Heipel
M D
MD
Burkhead
S K
SK
Kramer
J M
JM
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001792:Blood Platelets / Q000166:cytology*; D002454:Cell Differentiation; D002460:Cell Line; D003001:Cloning, Molecular; D006224:Cricetinae; D018076:DNA, Complementary; D004921:Erythropoietin / Q000737:chemistry; D006801:Humans; D008024:Ligands; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D009154:Mutation; D009363:Neoplasm Proteins; D021382:Protein Sorting Signals / Q000235:genetics; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D018121:Receptors, Cytokine; D011971:Receptors, Immunologic / Q000378:metabolism*; D053628:Receptors, Thrombopoietin; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013926:Thrombopoietin / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
D018076:DNA, Complementary; D008024:Ligands; C000715470:MAS1 protein, human; D009363:Neoplasm Proteins; D021382:Protein Sorting Signals; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D018121:Receptors, Cytokine; D011971:Receptors, Immunologic; D053628:Receptors, Thrombopoietin; D011994:Recombinant Proteins; D004921:Erythropoietin; C082218:MPL protein, human; D013926:Thrombopoietin