[
International Worm Meeting,
2007]
Lamins are nuclear-specific intermediate filament proteins (IFs) that, together with a complex set of inner nuclear membrane proteins, form a filamentous meshwork between the inner nuclear membrane and the peripheral chromatin. Lamins are involved in most nuclear activities; and mutations in human lamins or their associated proteins cause laminopathic diseases ranging from muscular dystrophies to accelerated ageing. Previous studies showed that lamin dimers form filamentous structures through ‘head-to-tail interactions, which then form paracrystalline structures in vitro. C.elegans has a single evolutionarily conserved lamin protein, termed Ce-lamin. This lamin is unique in its ability to form under specific conditions 10-nm filaments, similar to other IFs. We have used both negative staining and cryo-electron tomography to determine the structure of the 10-nm filaments and to find how mutations in residues, which are conserved in human lamin A and lead to laminopathic diseases, affect lamin filaments assembly. We have further analyzed the effects of these mutations on lamin organization and dynamics in vivo, by creating mutated gfp::Ce-lamin transgenic strains and by performing FRAP experiments. Our results show for the first time the structure of the lamin filament as well as how mutations affect the filament assembly both in vitro and in vivo.