Role of Nuclear Interactions of Paramyxoviral Matrix Proteins: Cellular ANP32B in Host Manipulation and Virus Replication

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We recent identified cellular acidic leucine-rich nuclear phosphoprotein 32 family member B (ANP32B) as a nuclear target for Hendra and Nipah virus matrix protein (M). Further preliminary data show that also another member of the paramyxovirus family is able to interact with ANP32B through M. We therefore conclude that targeting of ANP32B is part of a conserved mechanism, at least within the paramxovirinae subfamily. Identification of the detailed role of this interaction in virus replication and host cell manipulation may lead to identification of a so far unknown mechanism involved in replication and pathogenesis. To clarify the role of ANP32B targeting we here investigate (i) which viral M proteins can interact with the nuclear target, (ii) what sequences in the M proteins are required for specific interaction, (iii) how ANP32B influences virus replication and (iv) whether cellular functions of ANP32B in unconventional nuclear export, gene regulation and apoptosis inhibition are modulated by interacting M proteins. Host cell modulatory activities may play a substantial role in virus replication in infected hosts and thus are of high importance to understand virulence and pathogenesis of viruses. Within the project, established protein interaction assays will be combined with systematic mutagenesis of M proteins and generation of recombinant ANP32B-binding defective virus mutants. Influences on ANP32B functions will be addressed by specific assays for nuclear export, gene regulation and apoptosis detection in the presence of plasmid expressed M proteins and in virus infected cells. In vitro identification of specific M / ANP32B dependent molecular mechanisms and development of binding defective virus mutants will offer the outstanding possibility to investigate the role of ANP32B in disease development and immune escape. Whereas the work program of this three years proposal is focused on in vitro characterization of molecular mechanisms, in continuative work the developed virus mutants and knowledge about affected pathways will allow to investigate the role of the cellular interactor for in vivo replication and pathogenesis of henipa- and other paramyxoviruses. As this project focuses on a host-cell interface that may substantially contribute to replication and host manipulation, the proposed work will not only contribute to a better molecular understanding of virus replication but may also offer novel molecular targets for rational interference with virus replication or disease development.