Sm protein down-regulation leads to defects in nuclear pore complex disassembly and distribution in C. elegans embryos

Daphna Joseph-Strauss, Mátyás Gorjánácz, Rachel Santarella-Mellwig, Ekaterina Voronina, Anjon Audhya, Orna Cohen-Fix*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Nuclear pore complexes (NPCs) are large macromolecular structures embedded in the nuclear envelope (NE), where they facilitate exchange of molecules between the cytoplasm and the nucleoplasm. In most cell types, NPCs are evenly distributed around the NE. However, the mechanisms dictating NPC distribution are largely unknown. Here, we used the model organism . Caenorhabditis elegans to identify genes that affect NPC distribution during early embryonic divisions. We found that down-regulation of the Sm proteins, which are core components of the spliceosome, but not down-regulation of other splicing factors, led to clustering of NPCs. Down-regulation of Sm proteins also led to incomplete disassembly of NPCs during mitosis, but had no effect on lamina disassembly, suggesting that the defect in NPC disassembly was not due to a general defect in nuclear envelope breakdown. We further found that these mitotic NPC remnants persisted on an ER membrane that juxtaposes the mitotic spindle. At the end of mitosis, the remnant NPCs moved toward the chromatin and the reforming NE, where they ultimately clustered by forming membrane stacks perforated by NPCs. Our results suggest a novel, splicing-independent, role for Sm proteins in NPC disassembly, and point to a possible link between NPC disassembly in mitosis and NPC distribution in the subsequent interphase.

Original languageAmerican English
Pages (from-to)445-457
Number of pages13
JournalDevelopmental Biology
Issue number2
StatePublished - 15 May 2012
Externally publishedYes

Bibliographical note

Funding Information:
We thank Kevin O'Connell, Iain Mattaj and Geraldine Seydoux for advice and comments on the manuscript. We thank Andy Golden and members of the Golden lab for reagents and invaluable assistance. D. J. S. and O. C. F. are supported by an intramural NIDDK grant. A. A. is supported by an NIH grant GM088151 . E. V. was supported by an NIH fellowship 5F32GM080923 .


  • Early embryonic divisions
  • Nuclear envelope breakdown
  • Nuclear pore complex
  • Sm proteins


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