First published online July 23, 2008
Journal of Cell Science 121, 1501e (2008)
© The Company of Biologists Limited
BAF takes the lead in NE formation
The assembly of the nuclear envelope (NE) during telophase is a key step in mitosis, and mutations in NE proteins lead to several diseases – the nuclear laminopathies. The DNA-binding protein BAF is thought to have an important role in NE formation, but the dynamics of this process in vivo are not well understood. Tokuko Haraguchi and colleagues previously showed that BAF accumulates at the `core' region – the area of the telophase chromosome mass that sits close to the microtubules (MTs) of the mitotic spindle. Now, on page 2540, the authors show that BAF (as a GFP-fusion protein) accumulates at the core region earlier than several other NE proteins (including lamin A and emerin) and, once there, interacts directly with lamin A, emerin and itself. Moreover, FRAP analysis indicates that BAF-GFP at the core region is highly immobile, and electron microscopy shows that BAF forms an electron-dense structure on telophase chromosomes. When BAF is knocked down, the authors show, NE formation is perturbed; in addition, BAF does not assemble at the core when cells are treated with the MT-depolymerising reagent nocodazole. The authors propose a model in which BAF assembles in an MT-dependent manner and recruits NE precursor vesicles that contain other core-region proteins. Their data have implications for the treatment of nuclear laminopathies.

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Related articles in JCS:
- Live cell imaging and electron microscopy reveal dynamic processes of BAF-directed nuclear envelope assembly
- Tokuko Haraguchi, Tomoko Kojidani, Takako Koujin, Takeshi Shimi, Hiroko Osakada, Chie Mori, Akitsugu Yamamoto, and Yasushi Hiraoka
JCS 2008 121: 2540-2554.
[Abstract]
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