title: Thrombopoietin upregulates nucleolin mRNA and protein in thrombopoietin-dependent megakaryocytic cell line, UT-7/TPO.
abstract: Thrombopoietin (TPO) is a hematopoietic cytokine that regulates megakaryocytosis and thrombocytosis by binding to its receptor (c-Mpl). The signaling pathways downstream of c-Mpl include the Ras/Raf/MAP kinase and JAK/STAT pathway and are transduced into the regulation of immediate early-, early- and delayed-response genes. How these genes couple c-Mpl activation to the biochemical machinery of cell growth and cell cycle progression in hematopoietic cells is still unclear. UT-7/TPO is a recently characterized TPO-dependent cell line. Using RNA fingerprinting with arbitrarily primed PCR (RAP-PCR) to identify the TPO-regulated genes in this cell line, we found that the mRNA expression of nucleolin was upregulated in the UT-7/TPO cells in response to TPO. Concomitantly, the TPO-stimulated cells expressed an increased amount of full length nucleolin as determined by immunoblot analysis. The TPO-induced upregulation of nucleolin mRNA was not inhibited by the MEK1/2 inhibitor PD98059, suggesting that ERK/MAPK activation is not necessary for elevation of nucleolin gene expression in response to TPO in UT-7/TPO. Nucleolin is a multifunctional nucleolar protein thought to be involved in many cellular processes, including ribosome biogenesis, the processing of ribosomal RNA (rRNA), mRNA stability, transcriptional regulation, and cell proliferation. Thus, these results indicate that the upregulation of nucleolin mRNA and protein may be important for the TPO-induced effects of hematopoietic cells.
authors.affiliation: Japanese Red Cross, Hokkaido Red Cross Blood Center, Sapporo, Japan.
authors.forename: Takatoshi
authors.initials: T
authors.lastname: Ito
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Fujihara
authors.forename: Atsushi
authors.initials: A
authors.lastname: Oda
authors.forename: Shinobu
authors.initials: S
authors.lastname: Wakamoto
authors.forename: Miki
authors.initials: M
authors.lastname: Yamaguchi
authors.forename: Norio
authors.initials: N
authors.lastname: Komatsu
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Miyazaki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Azuma
authors.forename: Hisami
authors.initials: H
authors.lastname: Ikeda
authors.forename: Kenji
authors.initials: K
authors.lastname: Ikebuchi
mesh_terms: D001483:Base Sequence; D002460:Cell Line; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D020869:Gene Expression Profiling / Q000379:methods; D008533:Megakaryocytes / Q000166:cytology* / Q000187:drug effects; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D016133:Polymerase Chain Reaction / Q000379:methods; D012333:RNA, Messenger / Q000187:drug effects; D016601:RNA-Binding Proteins / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D013926:Thrombopoietin / Q000494:pharmacology*; D015854:Up-Regulation / Q000187:drug effects*; D000097796:Nucleolin
chemical_list: D004791:Enzyme Inhibitors; D005419:Flavonoids; D020928:Mitogen-Activated Protein Kinases; D010750:Phosphoproteins; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D013926:Thrombopoietin; D000097796:Nucleolin; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one