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Journal of Cell Biology
Simcha, I., Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
Shtutman, M., Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
Salomon, D., Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
Zhurinsky, J., Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
Sadot, E., Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
Geiger, B., Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
Ben-Ze'ev, A., Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
β-Catenin and plakoglobin are homologous proteins that function in cell adhesion by linking cadherins to the cytoskeleton and in signaling by transactivation together with lymphoid-enhancing binding/T cell (LEF/TCF) transcription factors. Here we compared the nuclear translocation and transactivation abilities of β-catenin and plakoglobin in mammalian cells. Overexpression of each of the two proteins in MDCK cells resulted in nuclear translocation and formation of nuclear aggregates. The β-catenin-containing nuclear structures also contained LEF-1 and vinculin, while plakoglobin was inefficient in recruiting these molecules, suggesting that its interaction with LEF-1 and vinculin is significantly weaker. Moreover, transfection of LEF-1 translocated endogenous β-catchin, but not plakoglobin to the nucleus. Chimeras consisting of Gal4 DNA-binding domain and the transactivation domains of either plakoglobin or β-catenin were equally potent in transactivating a Gal4-responsive reporter, whereas activation of LEF-1- responsive transcription was significantly higher with β-catenin. Overexpression of wild-type plakoglobin or mutant β-catenin lacking the transactivation domain induced accumulation of the endogenous β-catenin in the nucleus and LEF-1-responsive transactivation. It is further shown that the constitutive β-catenin-dependent transactivation in SW480 colon carcinoma cells and its nuclear localization can be inhibited by overexpressing N-cadherin or α-catenin. The results indicate that (a) plakoglobin and β-catenin differ in their nuclear translocation and complexing with LEF-1 and vinculin; (b) LEF-1-dependent transactivation is preferentially driven by β-catenin; and (c) the cytoplasmic partners of β- catchin, cadherin and α-catenin, can sequester it to the cytoplasm and inhibit its transcriptional activity.
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הספר "אוצר וולקני"
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תנאי שימוש
Differential nuclear translocation and transactivation potential of β- Catenin and plakoglobin
141
Simcha, I., Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
Shtutman, M., Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
Salomon, D., Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
Zhurinsky, J., Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
Sadot, E., Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
Geiger, B., Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
Ben-Ze'ev, A., Department of Molecular Cell Biology, Weizmann Institute of Science, Rehovot 76100, Israel
Differential nuclear translocation and transactivation potential of β- Catenin and plakoglobin
β-Catenin and plakoglobin are homologous proteins that function in cell adhesion by linking cadherins to the cytoskeleton and in signaling by transactivation together with lymphoid-enhancing binding/T cell (LEF/TCF) transcription factors. Here we compared the nuclear translocation and transactivation abilities of β-catenin and plakoglobin in mammalian cells. Overexpression of each of the two proteins in MDCK cells resulted in nuclear translocation and formation of nuclear aggregates. The β-catenin-containing nuclear structures also contained LEF-1 and vinculin, while plakoglobin was inefficient in recruiting these molecules, suggesting that its interaction with LEF-1 and vinculin is significantly weaker. Moreover, transfection of LEF-1 translocated endogenous β-catchin, but not plakoglobin to the nucleus. Chimeras consisting of Gal4 DNA-binding domain and the transactivation domains of either plakoglobin or β-catenin were equally potent in transactivating a Gal4-responsive reporter, whereas activation of LEF-1- responsive transcription was significantly higher with β-catenin. Overexpression of wild-type plakoglobin or mutant β-catenin lacking the transactivation domain induced accumulation of the endogenous β-catenin in the nucleus and LEF-1-responsive transactivation. It is further shown that the constitutive β-catenin-dependent transactivation in SW480 colon carcinoma cells and its nuclear localization can be inhibited by overexpressing N-cadherin or α-catenin. The results indicate that (a) plakoglobin and β-catenin differ in their nuclear translocation and complexing with LEF-1 and vinculin; (b) LEF-1-dependent transactivation is preferentially driven by β-catenin; and (c) the cytoplasmic partners of β- catchin, cadherin and α-catenin, can sequester it to the cytoplasm and inhibit its transcriptional activity.
Scientific Publication
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