A novel binding factor of 14-3-3beta functions as a transcriptional repressor and promotes anchorage-independent growth, tumorigenicity, and metastasis.
The 14-3-3 proteins form a highly conserved family of dimeric proteins that interact with various signal transduction proteins and regulate cell cycle, apoptosis, stress response, and malignant transformation. We previously demonstrated that the beta isoform of 14-3-3 proteins promotes tumorigenicity and angiogenesis of rat hepatoma K2 cells. In this study, to analyze the mechanism of 14-3-3beta-induced malignant transformation, yeast two-hybrid screening was performed, and a novel 14-3-3beta-binding factor, FBI1 (fourteen-three-three beta interactant 1), was identified. In vitro binding and co-immunoprecipitation analyses verified specific interaction of 14-3-3beta with FBI1. The strong expression of FBI1 was observed in several tumor cell lines but not in non-tumor cell lines. Forced expression of antisense FBI1 in K2 cells inhibited anchorage-independent growth but had no significant effect on cell proliferation in monolayer culture. Down-regulation of FBI1 also inhibited tumorigenicity and metastasis accompanying a decrease in MMP-9 (matrix metalloproteinase-9) expression. In addition, the duration of ERK1/2 activation was curtailed in antisense FBI1-expressing K2 cells. A luciferase reporter assay revealed that the FBI1-14-3-3beta complex could act as a transcriptional silencer, and MKP-1 (MAPK phosphatase-1) was one of the target genes of the FBI1-14-3-3beta complex. Moreover, chromatin immunoprecipitation analysis demonstrated that FBI1 and 14-3-3beta were presented on the MKP-1 promoter. These results indicate that FBI1 promotes sustained ERK1/2 activation through repression of MKP-1 transcription, resulting in promotion of tumorigenicity and metastasis.
Komiya
Yuko
Y
Department of Biological Science and Technology, Faculty of Industrial Science and Technology, Tokyo University of Science, Yamazaki 2641, Noda-shi, Chiba 278-8510, Japan.
Kurabe
Nobuya
N
Katagiri
Kumiko
K
Ogawa
Makiko
M
Sugiyama
Akinori
A
Kawasaki
Yasushi
Y
Tashiro
Fumio
F
D048948:14-3-3 Proteins / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D017209:Apoptosis; D001483:Base Sequence; D002453:Cell Cycle; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D015536:Down-Regulation; D054638:Dual Specificity Phosphatase 1 / Q000096:biosynthesis / Q000235:genetics; D004789:Enzyme Activation; D020780:Matrix Metalloproteinase 9 / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D009362:Neoplasm Metastasis; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D009389:Neovascularization, Pathologic / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D051381:Rats; D011916:Rats, Inbred F344; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000235:genetics; D020798:Two-Hybrid System Techniques
D048948:14-3-3 Proteins; D004268:DNA-Binding Proteins; D046912:Multiprotein Complexes; D009363:Neoplasm Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; C117093:Zbtb7a protein, mouse; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D054638:Dual Specificity Phosphatase 1; C517020:Dusp1 protein, mouse; C517021:Dusp1 protein, rat; D020780:Matrix Metalloproteinase 9