Panté Lab

Nelly Panté


Ph.D., Brandeis University, USA
M.Sc., The Venezuelan Institute for Scientific Research (IVIC), Caracas, Venezuela
B.Sc. (Hons.), Simon Bolivar University, Caracas, Venezuela

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My laboratory studies one of the fundamental molecular trafficking pathways within the cell: bidirectional transport of macromolecules between the nucleus and the cytoplasm. To investigate this problem we use cellular and molecular techniques in combination with fluorescence and electron microscopy. We also explore possible practical applications by incorporating viral research into our studies. We study how viruses deliver their genome to the cell nucleus. These studies on nuclear import of viral genomes are of particular importance because they may lead to the development of treatments and drugs that block nuclear uptake of viruses and thereby viral replication and propagation of infections. The viruses presently under investigation in our lab include Influenza virus, Hepatitis B virus and parvoviruses.
Molecular trafficking between the nucleus and the cytoplasm occurs through specialized multi-protein channels called nuclear pore complexes (NPCs). As the NPC is the major player in nucleocytoplasmic transport, we are also molecularly and structurally characterizing the NPC.

Figure 1: Current NPC model with its major structural components together with immuno-EM localization of the nucleoporins Nup358/RanBP2 and Nup153. Key referenes: Panté et al., 2000; Fahrenkrog et al., 1998; Panté and Aebi 1996c; Panté et al., 1994.

To study nuclear import in vivo we use a model system consisting on microinjection of transport substrates into the cytoplasm of Xenopus oocytes in combination with colloidal gold labeling and high-resolution electron microscopy.

Figure 2: A visualization of nuclear import of proteins by EM. Electron micrographs show gold particles coated with a nuclear protein (nucleoplasmin) entering the nucleus through the NPC. Different steps of nuclear import are depicted and also illustrated with schematic diagrams. For these experiments gold-conjugated nucleoplasmin was injected into the cytoplasm of Xenopus oocytes, which were then fixed and prepared for EM at different times following injection. Key referenes: Görlich et al., 1996; Panté and Aebi 1996a.

For the studies of nuclear import of viruses we also use the Xenopus system, as well as cells infected with virus followed by visualization using indirect immuno-localization and fluorescence microscopy.

Figure 3: Examples of our studies of nuclear import of (a) Hepatitis B virus (HBV) capsids and (b) the parvovirus minute virus of mice (MVM). (a) Electron micrographs of NPC cross-sections from Xenopus oocytes that have been mock injected with PBS or injected with mature authentic capsid (MatC) or capsids expressed in E. Coli (EcPC). Arrowheads point to capsids associated with the nuclear face of the NPC, demonstrating that intact HBV capsids are able to cross the NPC. (b) Confocal immunofluorescence image of a cell infected with MVM. MVM (in green) and NPCs (in red) were detected by immuostaining. Key referenes: Rabe et al., 2003; Panté and Kann 2002.