TY - JOUR
T1 - Inactivation of a c-Myb/estrogen receptor fusion protein in transformed primary cells leads to granulocyte/macrophage differentiation and down regulation of c-kit but not c-myc cdc2
AU - Hogg, Annette
AU - Schirm, Sabine
AU - Nakagoshi, Hideki
AU - Bartley, Paul
AU - Ishii, Shunsuke
AU - Bishop, J. Michael
AU - Gonda, Thomas J.
N1 - Funding Information:
The authors thank Giresh Chandran and Petranel Ferrao for their contributions to the preliminary stages of this work, and Dr David Horsfall (Flinders Medical Centre, Adelaide) for performing the estrogen receptor assays. This work was supported in part by a project grant (to TJG) from the National Health and Medical Research Council (NHMRC) of Australia. AH was supported by an NHMRC post-doctoral fellowship, PB is the recipient of a Dawes postgraduate scholarship from the Royal Adelaide Hospital, and TJG is a Senior Research Fellow of the NHMRC.
PY - 1997
Y1 - 1997
N2 - Primary murine fetal hemopoietic cells were transformed with a fusion protein consisting of the ligand-binding domain of the estrogen receptor and a carboxyl-terminally truncated c-Myb protein (ERMYB). The ERMYB-transformed hemopoietic cells exhibit an immature myeloid phenotype when grown in the presence of β-estradiol. Upon removal of β-estradiol, the ERMYB cells display increased adherence, decreased clonogenicity and differentiate to cells exhibiting granulocyte or macrophage morphology. The expression of the c-myc, c-kit, cdc2 and bcl-2 genes, which are putatively regulated by Myb, was investigated in ERMYB cells grown in the presence or absence of β-estradiol. Neither c-myc nor cdc2 expression was down-regulated after removal of β-estradiol demonstrating that differentiation is not a consequence of decreased transactivation of these genes by ERMYB. While bcl-2 expression was reduced by 50% in ERMYB cells grown in the absence of β-estradiol, there was no increase in DNA laddering, suggesting that Myb was not protecting ERMYB cells from apoptosis. In contrast, a substantial (200-fold) decrease in c-kit mRNA level was observed following differentiation of ERMYB cells, and c-kit mRNA could be partially re-induced by the re-addition of β-estradiol. Furthermore, a reporter construct containing the c-kit promoter was activated when cotransfected with a Myb expression vector, providing further evidence of a role for Myb in the regulation of c-kit.
AB - Primary murine fetal hemopoietic cells were transformed with a fusion protein consisting of the ligand-binding domain of the estrogen receptor and a carboxyl-terminally truncated c-Myb protein (ERMYB). The ERMYB-transformed hemopoietic cells exhibit an immature myeloid phenotype when grown in the presence of β-estradiol. Upon removal of β-estradiol, the ERMYB cells display increased adherence, decreased clonogenicity and differentiate to cells exhibiting granulocyte or macrophage morphology. The expression of the c-myc, c-kit, cdc2 and bcl-2 genes, which are putatively regulated by Myb, was investigated in ERMYB cells grown in the presence or absence of β-estradiol. Neither c-myc nor cdc2 expression was down-regulated after removal of β-estradiol demonstrating that differentiation is not a consequence of decreased transactivation of these genes by ERMYB. While bcl-2 expression was reduced by 50% in ERMYB cells grown in the absence of β-estradiol, there was no increase in DNA laddering, suggesting that Myb was not protecting ERMYB cells from apoptosis. In contrast, a substantial (200-fold) decrease in c-kit mRNA level was observed following differentiation of ERMYB cells, and c-kit mRNA could be partially re-induced by the re-addition of β-estradiol. Furthermore, a reporter construct containing the c-kit promoter was activated when cotransfected with a Myb expression vector, providing further evidence of a role for Myb in the regulation of c-kit.
KW - Apoptosis
KW - Apoptosis target genes
KW - Bcl-2
KW - Differentiation
KW - Myb
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U2 - 10.1038/sj.onc.1201472
DO - 10.1038/sj.onc.1201472
M3 - Article
C2 - 9416832
AN - SCOPUS:0031455764
VL - 15
SP - 2885
EP - 2898
JO - Oncogene
JF - Oncogene
SN - 0950-9232
IS - 24
ER -