Regulated docking of nuclear membrane vesicles to vimentin filaments during mitosis.
During mitosis, several types of intermediate-sized filaments (IFs) undergo an extensive remodelling in response to phosphorylation by cdc 2 and other protein kinases. However, unlike the nuclear lamins, the cytoplasmic IFs do not seem to follow a fixed disassembly stereotype and often retain their physical continuity without depolymerizing into soluble subunits. To investigate potential interactions between mitotically modified IFs and other cellular structures, we have examined prometaphase-arrested cells expressing the IF protein vimentin. We demonstrate here that vimentin filaments associate in situ and co-fractionate with a distinct population of mitotic vesicles. These vesicles carry on their surfaces nuclear lamin B, the inner nuclear membrane protein p58, and wheat germ agglutinin (WGA)-binding proteins. Consistent with a tight interaction between the IFs and the mitotic membranes, vimentin, nuclear lamin B, and a 180-kD WGA-binding protein are co-isolated when whole mitotic homogenates are incubated with anti-vimentin or anti-lamin B antibodies immobilized on magnetic beads. The vimentin-associated vesicles are essentially depleted of ER, Golgi and endosomal membrane proteins. The interaction of vimentin with lamin B-carrying membranes depends on phosphorylation and is weakened by dephosphorylation during nuclear reassembly in vitro. These observations reveal a novel interaction between IFs and cellular membranes and further suggest that the vimentin filaments may serve as a transient docking site for inner nuclear membrane vesicles during mitosis.
Maison
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C
Program of Cell Biology, European Molecular Biology Laboratory, Heidelberg, Federal Republic of Germany.
Horstmann
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H
Georgatos
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SD
D000818:Animals; D002451:Cell Compartmentation; D002460:Cell Line; D006224:Cricetinae; D005455:Fluorescent Antibody Technique; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D007382:Intermediate Filaments / Q000378:metabolism*; D034921:Lamin Type B; D034882:Lamins; D008938:Mitosis; D009685:Nuclear Envelope / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D010766:Phosphorylation; D014746:Vimentin / Q000378:metabolism*
D034921:Lamin Type B; D034882:Lamins; D009687:Nuclear Proteins; D014746:Vimentin