Talk abstracts

Talk on Monday 04:30-04:45pm submitted by Mahesh Chemudupati

Gle1 Translocates from the nuclear pore complex to the nuclear membrane during mitosis in Aspergillus nidulans

Mahesh Chemudupati (OSBP, Dept of Molecular Genetics, Ohio State University), Aysha H. Osmani (Dept of Molecular Genetics, Ohio State University), Stephen A. Osmani (OSBP, Dept of Molecular Genetics, Ohio State University)

Abstract:
During mitosis in Aspergillus nidulans, a subset of nuclear pore complex proteins (Nups) disperses from the core pore structure. This subset of Nups includes all budding yeast orthologs classified as peripheral Nups, with one exception. The predicted peripheral Nup An-Gle1 is unique in that it remains at the nuclear envelope (NE) during mitosis, an attribute typical of core Nups (Osmani et al. Mol. Biol. Cell, 17, 4946–4961, 2006). Additionally, GFP labeled An-Gle1 is distinctly located at the nuclear membrane surrounding the nucleolus during mitosis (Ukil et al. Mol. Biol. Cell, 20, 2132–2145, 2009). Affinity purification of all known Nups in A. nidulans identified a protein that co-purified with An-Gle1. This protein, AN0162, has a predicted C-terminal transmembrane domain. Endogenously GFP-tagged full-length AN0162 locates to the nuclear membrane throughout mitosis in a manner identical to An-Gle1 as does the GFP-tagged C-terminal half of the protein. Further analysis showed that AN0162 is responsible for tethering An-Gle1 to the NE specifically during mitosis, but not during interphase. This is the first known instance of a protein targeted to the NE by two different mechanisms. An-Gle1 is targeted to NPCs during interphase, but during mitosis An-Gle1 is targeted to the nuclear membrane by associating with AN0162. Our findings thus agree with the categorization of An-Gle1 as a peripheral Nup. This expands our knowledge of how proteins can be targeted to the NE in a regulated cell-cycle dependent manner.

References:
1. De Souza, C.P. et al. (2004) Partial nuclear pore complex disassembly
during closed mitosis in Aspergillus nidulans. Curr. Biol. 14, 1973–
1984.
2. Osmani, A.H. et al. (2006) Systematic deletion and mitotic localization
of the nuclear pore complex proteins of Aspergillus nidulans. Mol. Biol.
Cell 17, 4946–4961
3. Ukil, L. et al. (2009) Nucleolar separation from chromosomes during
Aspergillus nidulans mitosis can occur without spindle forces. Mol.
Biol. Cell 20, 2132–2145

Keywords: nuclear envelope, cell cycle, mitosis