title: Correlation of PU.1 and signal regulatory protein α1 expression in PU.1             transgenic K562 cells.
abstract: PU.1 is a key transcription factor for hematopoiesis and the reduction of             this protein expression plays important roles in various hematological malignancies.             To identify PU.1 downstream target genes, we recently reported dual microarray             analyses, using PU.1 knockdown K562 (K562PU.1KD) cells stably expressing short             inhibitory RNAs versus control cells and PU.1-overexpressing K562 (K562PU.1OE)             cells versus control cells. Several PU.1 candidate target genes, including cell             surface receptor, signal regulatory protein (SIRP) α1, were identified. In this             study, we revealed that the expression of SIRPα1 is positively correlated with             the expression of PU.1 in various K562PU.1KD and K562PU.1OE cells, shown by real-time             PCR and flow cytometry analyses. SIRPα1 is a negative regulator of signaling and             its reduced expression is considered to play a role in the pathogenesis of hematological             malignancies through the activation of downstream signaling pathways. By comparing             3 different clones of K562PU.1KD cells to their controls, we found constitutive             phosphorylation of the extracellular signal-regulated kinase (ERK), but not of             Akt, in these cells. Taken together, the down-regulation of PU.1 expression suppresses             the expression of SIRPα1, which may play a role in the aberrant activation of             ERK in these cells.
authors.affiliation: Division of Molecular Hematology, Kitasato University Graduate                     School of Medical Sciences, Sagamihara, Japan.
authors.forename: Yuko
authors.initials: Y
authors.lastname: Iseki
authors.forename: Masako
authors.initials: M
authors.lastname: Nakahara
authors.forename: Makoto
authors.initials: M
authors.lastname: Kubo
authors.forename: Fumiya
authors.initials: F
authors.lastname: Obata
authors.forename: Hideo
authors.initials: H
authors.lastname: Harigae
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Takahashi
mesh_terms: D000943:Antigens, Differentiation / Q000235:genetics* / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D055785:Gene Knockdown Techniques; D020868:Gene Silencing; D006801:Humans; D020014:K562 Cells; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000378:metabolism; D011971:Receptors, Immunologic / Q000235:genetics* / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics* / Q000378:metabolism; D019076:Transgenes; D000099232:Proto-Oncogene Protein Spi-1
chemical_list: D000943:Antigens, Differentiation; D011518:Proto-Oncogene Proteins; D011971:Receptors, Immunologic; D015534:Trans-Activators; D000099232:Proto-Oncogene Protein Spi-1; C501920:SIRPA protein, human