scholarly journals Cytoplasmic Parvovirus Capsids Recruit Importin Beta for Nuclear Delivery

2019 ◽  
Vol 94 (4) ◽  
Author(s):  
Elina Mäntylä ◽  
Vesa Aho ◽  
Michael Kann ◽  
Maija Vihinen-Ranta
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Pore Complex ◽  
Nuclear Import ◽  
Laser Scanning ◽  
Mixed Model ◽  
Laser Scanning Confocal Microscopy ◽  
Nuclear Pore ◽  
Cancer Therapies ◽  
Nuclear Entry ◽  
Scanning Confocal Microscopy

ABSTRACT 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 nucleoporin 153-mediated interactions on the nuclear side. The importin β-capsid interaction continued within the nucleoplasm, which suggests a mixed model of nuclear entry in which the classical nuclear import across the nuclear pore complex is accompanied by transient ruptures of the nuclear envelope, also allowing the passive entry of importin β-capsid complexes into the nucleus. IMPORTANCE Parvoviruses are small DNA viruses that deliver their DNA into the postmitotic nuclei, which is an important step for parvoviral gene and cancer therapies. Limitations in virus-receptor interactions or endocytic entry do not fully explain the low transduction/infection efficiency, indicating a bottleneck after virus entry into the cytoplasm. We thus investigated the transfer of parvovirus capsids from the cytoplasm to the nucleus, showing that the nuclear import of the parvovirus capsid follows a unique strategy, which differs from classical nuclear import and those of other viruses.

Distribution of a nuclear envelope antigen during the syncytial mitoses of the early Drosophila embryo as revealed by laser scanning confocal microscopy

1992 ◽  
Vol 102 (2) ◽  
pp. 299-305
Author(s):  
M.G. Riparbelli ◽  
G. Callaini
Keyword(s):  
Nuclear Envelope ◽  
Laser Scanning ◽  
Laser Scanning Confocal Microscopy ◽  
Confocal Laser Scanning Microscope ◽  
Drosophila Embryo ◽  
Confocal Laser ◽  
Cytoplasmic Staining ◽  
Scanning Confocal Microscopy ◽  
Early Drosophila Embryo ◽  
Envelope Antigen

The changing distribution of a nuclear envelope antigen recognized by a monoclonal antibody raised against human fibroblast vimentin during the syncytial mitoses of the Drosophila embryo has been studied with a confocal laser scanning microscope. The antigen appears very early as irregular aggregates in the peripheral cytoplasm of the preblastoderm embryo. As the first nuclei reach the periplasm the antigen is localized on the nuclear envelope and the cytoplasmic staining decreases. In addition to the perinuclear labeling we observed intense midzone and polar staining during the mitotic cycle. A possible relationship between polar localization of the antigen and centrosome position is discussed.

scholarly journals A DNA-origami nuclear pore mimic reveals nuclear entry mechanisms of HIV-1 capsid

2020 ◽  
Author(s):  
Qi Shen ◽  
Chaoyi Xu ◽  
Sooin Jang ◽  
Qiancheng Xiong ◽  
Swapnil C. Devarkar ◽  
...  
Keyword(s):  
Nuclear Pore Complex ◽  
Nuclear Import ◽  
Dna Origami ◽  
Nuclear Pore ◽  
Nuclear Entry ◽  
Cellular Factors ◽  
Immunodeficiency Virus ◽  
Hiv 1 ◽  
Human Immunodeficiency Virus 1

SummaryThe capsid of human immunodeficiency virus 1 (HIV-1) plays a pivotal role in viral nuclear import, but the mechanism by which the viral core passages the nuclear pore complex (NPC) is poorly understood. Here, we use DNA-origami mimics of the NPC, termed NuPODs (NucleoPorins Organized by DNA), to reveal the mechanistic underpinnings of HIV-1 capsid nuclear entry. We found that trimeric interface formed via three capsid protein hexamers is targeted by a triple-arginine (RRR) motif but not the canonical phenylalanine-glycine (FG) motif of NUP153. As NUP153 is located on the nuclear face of the NPC, this result implies that the assembled capsid must cross the NPC in vivo. This hypothesis is corroborated by our observations of tubular capsid assemblies penetrating through NUP153 NuPODs. NUP153 prefers to bind highly curved capsid assemblies including those found at the tips of viral cores, thereby facilitating capsid insertion into the NPC. Furthermore, a balance of capsid stabilization by NUP153 and deformation by CPSF6, along with other cellular factors, may allow for the intact capsid to pass NPCs of various sizes. The NuPOD system serves as a unique tool for unraveling the previously elusive mechanisms of nuclear import of HIV-1 and other viruses.

DNA synthesis, microtubule and nuclear dynamics in porcine parthenotes

Zygote ◽  
1996 ◽  
Vol 4 (2) ◽  
pp. 139-144 ◽  
Author(s):  
Lin Liu ◽  
Caroline Lee ◽  
Robert M. Moor
Keyword(s):  
Confocal Microscopy ◽  
Nuclear Envelope ◽  
Dna Synthesis ◽  
Laser Scanning ◽  
Polar Body ◽  
Laser Scanning Confocal Microscopy ◽  
Lamin A ◽  
Nuclear Dynamics ◽  
Scanning Confocal Microscopy

SummaryParthenogenetically activated mammalian oocytes have been used in the past decade as cytoplasts, in an attempt to support the development of nuclear transplant embryos. The present experiments were undertaken to study the DNA synthesis and the organisation of microtubules, nuclear envelope and chromatin during the first cell cycle of electrically activated porcine oocytes (parthenotes) matured in vitro by using immunocytochemistry and laser scanning confocal microscopy. The results showed that pronuclear-like (PN) formation began 4–5 h post-activation (hpa), whilst DNA synthesis as revealed by bromodeoxyuridine incorporation was initiated 5–6 hpa, with a maximum number of labelled oocytes (73%) around 11 hpa, and persisted in some parthenotes until 15–16 hpa. In the metaphase II (MII) oocytes, microtubules were detected only in the metaphase II spindle; no lamin A/C antigen was observed. Electrical DC pulses resulted in 91% of MII oocytes being activated and confocal microscopy Indicated that microtubules were assembled in the spindle first for the extrusion of a second polar body, and for the second time for division from one to two cells. Nuclear envelope, indicated by anti-lamin A/C stain, was formed around the time of PN formation and surrounded the nuclear chromatin of 1- and 2-cell parthenogenotea. These results demonstrate that the apparent normality in both DNA synthesis and dynamics of microtubules and nuclear envelope is involved with chromosomal organisation in the parthenotes. In addition, the use of electrically activated IVM oocytes for both nuclear transfer and parthenogenetic studies in pigs is discussed.

scholarly journals SUN1 Regulates HIV-1 Nuclear Import in a Manner Dependent on the Interaction between the Viral Capsid and Cellular Cyclophilin A

2018 ◽  
Vol 92 (13) ◽  
pp. e00229-18 ◽  
Author(s):  
Xinlong Luo ◽  
Wei Yang ◽  
Guangxia Gao
Keyword(s):  
Nuclear Pore Complex ◽  
Nuclear Import ◽  
Leukemia Virus ◽  
Cyclophilin A ◽  
Cellular Protein ◽  
Wild Type Virus ◽  
Nuclear Pore ◽  
Nuclear Entry ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACTHuman immunodeficiency virus type 1 (HIV-1) can infect nondividing cells via passing through the nuclear pore complex. The nuclear membrane-imbedded protein SUN2 was recently reported to be involved in the nuclear import of HIV-1. Whether SUN1, which shares many functional similarities with SUN2, is involved in this process remained to be explored. Here we report that overexpression of SUN1 specifically inhibited infection by HIV-1 but not that by simian immunodeficiency virus (SIV) or murine leukemia virus (MLV). Overexpression of SUN1 did not affect reverse transcription but led to reduced accumulation of the 2-long-terminal-repeat (2-LTR) circular DNA and integrated viral DNA, suggesting a block in the process of nuclear import. HIV-1 CA was mapped as a determinant for viral sensitivity to SUN1. Treatment of SUN1-expressing cells with cyclosporine (CsA) significantly reduced the sensitivity of the virus to SUN1, and an HIV-1 mutant containing CA-G89A, which does not interact with cyclophilin A (CypA), was resistant to SUN1 overexpression. Downregulation of endogenous SUN1 inhibited the nuclear entry of the wild-type virus but not that of the G89A mutant. These results indicate that SUN1 participates in the HIV-1 nuclear entry process in a manner dependent on the interaction of CA with CypA.IMPORTANCEHIV-1 infects both dividing and nondividing cells. The viral preintegration complex (PIC) can enter the nucleus through the nuclear pore complex. It has been well known that the viral protein CA plays an important role in determining the pathways by which the PIC enters the nucleus. In addition, the interaction between CA and the cellular protein CypA has been reported to be important in the selection of nuclear entry pathways, though the underlying mechanisms are not very clear. Here we show that both SUN1 overexpression and downregulation inhibited HIV-1 nuclear entry. CA played an important role in determining the sensitivity of the virus to SUN1: the regulatory activity of SUN1 toward HIV-1 relied on the interaction between CA and CypA. These results help to explain how SUN1 is involved in the HIV-1 nuclear entry process.

Laser Scanning Confocal Microscopy and Three-Dimesnsional Reconstruction of the Mitotic Spindles of Unequally Dividing Embryonic Cells

1990 ◽  
Vol 48 (3) ◽  
pp. 166-167
Author(s):  
J. Holy ◽  
G. Schatten
Keyword(s):  
Confocal Microscopy ◽  
Mitotic Spindle ◽  
Laser Scanning ◽  
Three Dimensional ◽  
Laser Scanning Confocal Microscopy ◽  
Two Dimensions ◽  
Embryonic Cells ◽  
Mitotic Spindles ◽  
Cleavage Division ◽  
Scanning Confocal Microscopy

One of the classic limitations of light microscopy has been the fact that three dimensional biological events could only be visualized in two dimensions. Recently, this shortcoming has been overcome by combining the technologies of laser scanning confocal microscopy (LSCM) and computer processing of microscopical data by volume rendering methods. We have employed these techniques to examine morphogenetic events characterizing early development of sea urchin embryos. Specifically, the fourth cleavage division was examined because it is at this point that the first morphological signs of cell differentiation appear, manifested in the production of macromeres and micromeres by unequally dividing vegetal blastomeres.The mitotic spindle within vegetal blastomeres undergoing unequal cleavage are highly polarized and develop specialized, flattened asters toward the micromere pole. In order to reconstruct the three-dimensional features of these spindles, both isolated spindles and intact, extracted embryos were fluorescently labeled with antibodies directed against either centrosomes or tubulin.

Automated 3-D cell population analysis in thick tissue sections using laser-scanning confocal-microscopy data

1993 ◽  
Vol 51 ◽  
pp. 562-563
Author(s):  
Hakan Ancin
Keyword(s):  
Laser Scanning ◽  
Population Analysis ◽  
Three Dimensional ◽  
Large Data ◽  
Laser Scanning Confocal Microscopy ◽  
Tissue Slices ◽  
Scanning Confocal Microscopy ◽  
Tissue Sections ◽  
Spatially Adaptive ◽  
Microscopy Data

This paper presents methods for performing detailed quantitative automated three dimensional (3-D) analysis of cell populations in thick tissue sections while preserving the relative 3-D locations of cells. Specifically, the method disambiguates overlapping clusters of cells, and accurately measures the volume, 3-D location, and shape parameters for each cell. Finally, the entire population of cells is analyzed to detect patterns and groupings with respect to various combinations of cell properties. All of the above is accomplished with zero subjective bias.In this method, a laser-scanning confocal light microscope (LSCM) is used to collect optical sections through the entire thickness (100 - 500μm) of fluorescently-labelled tissue slices. The acquired stack of optical slices is first subjected to axial deblurring using the expectation maximization (EM) algorithm. The resulting isotropic 3-D image is segmented using a spatially-adaptive Poisson based image segmentation algorithm with region-dependent smoothing parameters. Extracting the voxels that were labelled as "foreground" into an active voxel data structure results in a large data reduction.

scholarly journals Advanced Static and Dynamic Fluorescence Microscopy Techniques to Investigate Drug Delivery Systems

Pharmaceutics ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 861
Author(s):  
Jacopo Cardellini ◽  
Arianna Balestri ◽  
Costanza Montis ◽  
Debora Berti
Keyword(s):  
Drug Delivery ◽  
Fluorescence Microscopy ◽  
Drug Delivery Systems ◽  
Laser Scanning ◽  
Super Resolution ◽  
Laser Scanning Confocal Microscopy ◽  
Delivery Systems ◽  
Scanning Confocal Microscopy ◽  
Biological Phenomena

In the past decade(s), fluorescence microscopy and laser scanning confocal microscopy (LSCM) have been widely employed to investigate biological and biomimetic systems for pharmaceutical applications, to determine the localization of drugs in tissues or entire organisms or the extent of their cellular uptake (in vitro). However, the diffraction limit of light, which limits the resolution to hundreds of nanometers, has for long time restricted the extent and quality of information and insight achievable through these techniques. The advent of super-resolution microscopic techniques, recognized with the 2014 Nobel prize in Chemistry, revolutionized the field thanks to the possibility to achieve nanometric resolution, i.e., the typical scale length of chemical and biological phenomena. Since then, fluorescence microscopy-related techniques have acquired renewed interest for the scientific community, both from the perspective of instrument/techniques development and from the perspective of the advanced scientific applications. In this contribution we will review the application of these techniques to the field of drug delivery, discussing how the latest advancements of static and dynamic methodologies have tremendously expanded the experimental opportunities for the characterization of drug delivery systems and for the understanding of their behaviour in biologically relevant environments.

scholarly journals Regulation and coordination of nuclear envelope and nuclear pore complex assembly

Nucleus ◽  
2013 ◽  
Vol 4 (2) ◽  
pp. 105-114 ◽  
Author(s):  
Michaela Clever ◽  
Yasuhiro Mimura ◽  
Tomoko Funakoshi ◽  
Naoko Imamoto
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Pore Complex ◽  
Nuclear Pore ◽  
Complex Assembly
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