0000000000074572
AUTHOR
Michael Kann
Cytoplasmic Parvovirus Capsids Recruit Importin Beta for Nuclear Delivery
Parvoviruses are an important platform for gene and cancer therapy. Their cell entry and the following steps, including nuclear import, are inefficient, limiting their use in therapeutic applications. Two models exist on parvoviral nuclear entry: the classical import of the viral capsid using nuclear transport receptors of the importin (karyopherin) family or the direct attachment of the capsid to the nuclear pore complex leading to the local disintegration of the nuclear envelope. Here, by laser scanning confocal microscopy and in situ proximity ligation analyses combined with coimmunoprecipitation, we show that infection requires importin β-mediated access to the nuclear pore complex and …
Nuclear entry and egress of parvoviruses.
Parvoviruses are small non-enveloped single-stranded DNA viruses, which depend on host cell nuclear transcriptional and replication machinery. After endosomal exposure of nuclear localization sequence and a phospholipase A2 domain on the capsid surface, and escape into the cytosol, parvovirus capsids enter the nucleus. Due to the small capsid diameter of 18–26 nm, intact capsids can potentially pass into the nucleus through nuclear pore complexes (NPCs). This might be facilitated by active nuclear import, but capsids may also follow an alternative entry pathway that includes activation of mitotic factors and local transient disruption of the nuclear envelope. The nuclear entry is followed b…
Concepts to Reveal Parvovirus–Nucleus Interactions
Parvoviruses are small single-stranded (ss) DNA viruses, which replicate in the nucleoplasm and affect both the structure and function of the nucleus. The nuclear stage of the parvovirus life cycle starts at the nuclear entry of incoming capsids and culminates in the successful passage of progeny capsids out of the nucleus. In this review, we will present past, current, and future microscopy and biochemical techniques and demonstrate their potential in revealing the dynamics and molecular interactions in the intranuclear processes of parvovirus infection. In particular, a number of advanced techniques will be presented for the detection of infection-induced changes, such as DNA modification…
Cytoplasmic parvovirus capsids recruit importin beta for nuclear delivery
Parvoviruses are an important platform for gene and cancer therapy. Their cell entry and the following steps including nuclear import are inefficient limiting their use in therapeutic applications. Two models exist on parvoviral nuclear entry: classical import of the viral capsid using nuclear transport receptors of the importin (karyopherin) family, or direct attachment of the capsid to the nuclear pore complex leading to local disintegration of the nuclear envelope. Here, by laser scanning confocal microscopy and in situ proximity ligation analysis combined with co-immunoprecipitation we showed that infection requires importin β-mediated access into the nuclear pore complex and nucleopori…
Viral highway to nucleus exposed by image correlation analyses.
AbstractParvoviral genome translocation from the plasma membrane into the nucleus is a coordinated multistep process mediated by capsid proteins. We used fast confocal microscopy line scan imaging combined with image correlation methods including auto-, pair- and cross-correlation, and number and brightness analysis, to study the parvovirus entry pathway at the single-particle level in living cells. Our results show that the endosome-associated movement of virus particles fluctuates from fast to slow. Fast transit of single cytoplasmic capsids to the nuclear envelope is followed by slow movement of capsids and fast diffusion of capsid fragments in the nucleoplasm. The unique combination of …
Protoparvovirus Knocking at the Nuclear Door
Protoparvoviruses target the nucleus due to their dependence on the cellular reproduction machinery during the replication and expression of their single-stranded DNA genome. In recent years, our understanding of the multistep process of the capsid nuclear import has improved, and led to the discovery of unique viral nuclear entry strategies. Preceded by endosomal transport, endosomal escape and microtubule-mediated movement to the vicinity of the nuclear envelope, the protoparvoviruses interact with the nuclear pore complexes. The capsids are transported actively across the nuclear pore complexes using nuclear import receptors. The nuclear import is sometimes accompanied by structural chan…
Impact of VP1-Specific Protein Sequence Motifs on Adeno-Associated Virus Type 2 Intracellular Trafficking and Nuclear Entry
ABSTRACT Adeno-associated virus type 2 (AAV2) has gained much interest as a gene delivery vector. A hallmark of AAV2-mediated gene transfer is an intracellular conformational change of the virus capsid, leading to the exposure of infection-relevant protein domains. These protein domains, which are located on the N-terminal portion of the structural proteins VP1 and VP2, include a catalytic phospholipase A 2 domain and three clusters of basic amino acids. We have identified additional protein sequence motifs located on the VP1/2 N terminus that also proved to be obligatory for virus infectivity. These motifs include signals that are known to be involved in protein interaction, endosomal sort…