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Published on: March 11, 2011
Specific nucleoporin requirement for Smad nuclear translocation
1Program in Molecular Medicine, University of Massachusetts Medical School, 373 Plantation Street, Worcester, MA 01605, USA. lan.xu@umassmed.edu.
Molecular and Cellular Biology
|June 16, 2010
Summary
Specific nucleoporins mediate the nuclear import of activated Smad1 (MAD) by interacting with importin Msk. This reveals a novel, cargo-specific role for nucleoporins in TGF-beta signaling beyond nuclear pore complex assembly.
Area of Science:
- Cell Biology
- Molecular Biology
- Signal Transduction
Background:
- Smad nuclear import is crucial for transforming growth factor beta (TGF-beta) signaling.
- The nuclear pore complex (NPC) regulates transport between the cytoplasm and nucleus.
- Specific roles of nucleoporins in cargo-selective nuclear import are not fully understood.
Purpose of the Study:
- To identify nucleoporins involved in the nuclear import of Smad1 (MAD).
- To elucidate the mechanism of activation-induced nuclear translocation of MAD.
- To determine if nucleoporins have cargo-specific functions in nuclear transport.
Main Methods:
- Utilized Drosophila melanogaster models for genetic and biochemical analyses.
- Investigated interactions between nucleoporins, Smad1 (MAD), and importin Msk.
- Assessed the impact of nucleoporin mutations on Smad nuclear import.
Main Results:
- Identified a subset of nucleoporins (Sec13, Nup75, Nup93, Nup205) mediating MAD nuclear import.
- Demonstrated that these nucleoporins function independently of their roles in NPC assembly.
- Showed that Sec13 and Nup93 preferentially bind activated MAD and recruit importin Msk.
Conclusions:
- Delineated a unique nucleoporin-dependent mechanism for MAD nuclear import.
- Revealed novel, cargo-specific functions for scaffold nucleoporins.
- Highlighted a distinct trans-NPC pathway for Smad nuclear translocation in TGF-beta signaling.
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