TY - JOUR
T1 - Functional Cloning of the Proto-oncogene Brain Factor-1 (BF-1) As a Smad-binding Antagonist of Transforming Growth Factor-β Signaling
AU - Rodriguez, Carlos
AU - Huang, Lily Jun Shen
AU - Son, Jennifer K.
AU - McKee, Adrienne
AU - Xiao, Zhan
AU - Lodish, Harvey F.
PY - 2001/8/10
Y1 - 2001/8/10
N2 - Using the plasminogen activator inhibitor (PAI) promoter to drive the expression of a reporter gene (mouse CD2), we devised a system to clone negative regulators of the transforming growth factor-β (TGF-β) signaling pathway. We infected a TGF-β-responsive cell line (MvLu1) with a retroviral cDNA library, selecting by fluorescence-activated cell sorter single cells displaying low PAI promoter activity in response to TGF-β. Using this strategy we cloned the proto-oncogene brain factor-1 (BF-1). BF-1 represses the PAI promoter in part by associating with both unphosphorylated Smad3 (in the cytoplasm) and phosphorylated Smad3 (in the nucleus), thus preventing its binding to DNA. BF-1 also associates with Smad1, -2, and -4; the Smad MH2 domain binds to BF-1, and the C-terminal segment of BF-1 is uniquely and solely required for binding to Smads. Further, BF-1 represses another TGF-β-induced promoter (p15), it upregulates a TGF-β-repressed promoter (Cyclin A), and it reverses the growth arrest caused by TGF-β. Our results suggest that BF-1 is a general inhibitor of TGF-β signaling and as such may play a key role during brain development.
AB - Using the plasminogen activator inhibitor (PAI) promoter to drive the expression of a reporter gene (mouse CD2), we devised a system to clone negative regulators of the transforming growth factor-β (TGF-β) signaling pathway. We infected a TGF-β-responsive cell line (MvLu1) with a retroviral cDNA library, selecting by fluorescence-activated cell sorter single cells displaying low PAI promoter activity in response to TGF-β. Using this strategy we cloned the proto-oncogene brain factor-1 (BF-1). BF-1 represses the PAI promoter in part by associating with both unphosphorylated Smad3 (in the cytoplasm) and phosphorylated Smad3 (in the nucleus), thus preventing its binding to DNA. BF-1 also associates with Smad1, -2, and -4; the Smad MH2 domain binds to BF-1, and the C-terminal segment of BF-1 is uniquely and solely required for binding to Smads. Further, BF-1 represses another TGF-β-induced promoter (p15), it upregulates a TGF-β-repressed promoter (Cyclin A), and it reverses the growth arrest caused by TGF-β. Our results suggest that BF-1 is a general inhibitor of TGF-β signaling and as such may play a key role during brain development.
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U2 - 10.1074/jbc.M102759200
DO - 10.1074/jbc.M102759200
M3 - Article
C2 - 11387330
AN - SCOPUS:0035839552
SN - 0021-9258
VL - 276
SP - 30224
EP - 30230
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 32
ER -