Translocation of beta-catenin into the nucleus independent of interactions with FG-rich nucleoporins.
beta-Catenin nuclear import has been found to be independent of classical nuclear localization signal (NLS) nuclear import factors. Here, we test the hypothesis that beta-catenin interacts directly with nuclear pore proteins to mediate its own transport. We show that beta-catenin, unlike importin-beta, does not interact detectably with Phe/Gly(FG)-repeat-rich nuclear pore proteins or nucleoporins (Nups). Moreover, unlike NLS-containing proteins, beta-catenin nuclear import is not inhibited by wheat germ agglutinin (WGA) or excess importin-beta. These results suggest beta-catenin nuclear translocation does not involve direct interactions with FG-Nups. However, beta-catenin has two regions that can target it to the nucleus, and its import is cold sensitive, indicating that beta-catenin nuclear import is still an active process. Transport is blocked by a soluble form of the C-cadherin cytoplasmic domain, suggesting that masking of the nuclear targeting signal may be a mechanism of regulating beta-catenin subcellular localization.
Neuroscience Program, Weill Graduate School of Medical Sciences of Cornell University, New York, NY 10021, USA.
Eun-Kyung
EK
Suh
Barry M
BM
Gumbiner
D021581:Active Transport, Cell Nucleus; D000818:Animals; D001692:Biological Transport; D019556:COS Cells; D002467:Cell Nucleus / Q000378:metabolism*; D002522:Chlorocebus aethiops; D003208:Concanavalin A / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D004151:Dipeptides / Q000378:metabolism*; D019913:Nuclear Localization Signals; D022022:Nuclear Pore; D028861:Nuclear Pore Complex Proteins / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000378:metabolism; D013696:Temperature; D015534:Trans-Activators / Q000378:metabolism*; D014909:Wheat Germ Agglutinins / Q000378:metabolism; D029867:Xenopus Proteins; D014982:Xenopus laevis / Q000378:metabolism; D051176:beta Catenin; D028961:beta Karyopherins / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism
C495266:CTNNB1 protein, Xenopus; D003598:Cytoskeletal Proteins; D004151:Dipeptides; D019913:Nuclear Localization Signals; D028861:Nuclear Pore Complex Proteins; D009687:Nuclear Proteins; D011994:Recombinant Proteins; D015534:Trans-Activators; D014909:Wheat Germ Agglutinins; D029867:Xenopus Proteins; D051176:beta Catenin; D028961:beta Karyopherins; D003208:Concanavalin A; C040500:phenylalanylglycine; D001616:beta-Galactosidase