THE ROLE OF THE NUCLEAR-PORE COMPLEX IN ADENOVIRUS DNA ENTRY

Adenovirus targets its genome to the cell nucleus by a multistep proce ss involving endocytosis, membrane penetration and cytoplasmic transpo rt, and finally imports its DNA into the nucleus. Using an immunochemi cal and biochemical approach combined with inhibitors of nuclear impor t, we demonstrate that incoming viral DNA and DNA-associated protein V U: enter the nucleus via nuclear pore complexes (NPCs). Depletion of c alcium from nuclear envelope and endoplasmic reticulum cisternae by io nophores or thapsigargin blocked DNA and protein VII import into the n ucleus, but had no effect on virus targeting to NPCs. Calcium-depleted cells were capable of disassembling incoming virus. In contrast, inhi bitors of cytosolic O-linked glycoproteins of the NPC blocked virus at tachment to the nuclear envelope, capsid disassembly and also nuclear import of protein VII. The data indicate that NPCs have multiple roles in adenovirus entry into cells: they contain a virus-binding and/or d issociation activity and provide a gateway for the incoming DNA genome into the nucleus.