C-Mannosylation of thrombopoietin receptor (c-Mpl) regulates thrombopoietin-dependent JAK-STAT signaling.
The thrombopoietin receptor, also known as c-Mpl, is a member of the cytokine superfamily, which regulates the differentiation of megakaryocytes and formation of platelets by binding to its ligand, thrombopoietin (TPO), through Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling. The loss-of-function mutations of c-Mpl cause severe thrombocytopenia due to impaired megakaryocytopoiesis, and gain-of-function mutations cause thrombocythemia. c-Mpl contains two Trp-Ser-Xaa-Trp-Ser (Xaa represents any amino acids) sequences, which are characteristic sequences of type I cytokine receptors, corresponding to C-mannosylation consensus sequences: Trp-Xaa-Xaa-Trp/Cys. C-mannosylation is a post-translational modification of tryptophan residue in which one mannose is attached to the first tryptophan residue in the consensus sequence via C-C linkage. Although c-Mpl contains some C-mannosylation sequences, whether c-Mpl is C-mannosylated or not has been uninvestigated. We identified that c-Mpl is C-mannosylated not only at Trp(269) and Trp(474), which are putative C-mannosylation site, but also at Trp(272), Trp(416), and Trp(477). Using C-mannosylation defective mutant of c-Mpl, the C-mannosylated tryptophan residues at four sites (Trp(269), Trp(272), Trp(474), and Trp(477)) are essential for c-Mpl-mediated JAK-STAT signaling. Our findings suggested that C-mannosylation of c-Mpl is a possible therapeutic target for platelet disorders.
Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan.
Yukiko
Y
Sasazawa
Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan.
Natsumi
N
Sato
Biomolecular Characterization Unit, RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako 351-0198, Japan.
Takehiro
T
Suzuki
Biomolecular Characterization Unit, RIKEN Center for Sustainable Resource Science, 2-1 Hirosawa, Wako 351-0198, Japan.
Naoshi
N
Dohmae
Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan. Electronic address: simizu@applc.keio.ac.jp.
Siro
S
Simizu
D000595:Amino Acid Sequence; D002460:Cell Line; D006801:Humans; D053612:Janus Kinases / Q000378:metabolism; D008969:Molecular Sequence Data; D053628:Receptors, Thrombopoietin / Q000737:chemistry / Q000378:metabolism*; D050791:STAT Transcription Factors / Q000378:metabolism*; D015398:Signal Transduction; D013926:Thrombopoietin / Q000378:metabolism*; D014364:Tryptophan / Q000031:analogs & derivatives* / Q000032:analysis / Q000378:metabolism
C101500:C(2)-mannosyltryptophan; D053628:Receptors, Thrombopoietin; D050791:STAT Transcription Factors; C082218:MPL protein, human; D014364:Tryptophan; D013926:Thrombopoietin; D053612:Janus Kinases
C-mannosylation; JAK-STAT; Post-translational modification; Thrombopoietin receptor; c-Mpl