scholarly journals Fate of the Inner Nuclear Membrane Protein Lamin B Receptor and Nuclear Lamins in Herpes Simplex Virus Type 1 Infection

2001 ◽  
Vol 75 (18) ◽  
pp. 8818-8830 ◽  
Author(s):  
Emily S. Scott ◽  
Peter O'Hare
Keyword(s):  
Herpes Simplex ◽  
Nuclear Membrane ◽  
Nuclear Lamina ◽  
Lamin B ◽  
Inner Nuclear Membrane ◽  
Lamin B Receptor ◽  
Infected Cells ◽  
Simplex Virus ◽  
Inner Nuclear Membrane Protein

ABSTRACT During herpesvirus egress, capsids bud through the inner nuclear membrane. Underlying this membrane is the nuclear lamina, a meshwork of intermediate filaments with which it is tightly associated. Details of alterations to the lamina and the inner nuclear membrane during infection and the mechanisms involved in capsid transport across these structures remain unclear. Here we describe the fate of key protein components of the nuclear envelope and lamina during herpes simplex virus type 1 (HSV-1) infection. We followed the distribution of the inner nuclear membrane protein lamin B receptor (LBR) and lamins A and B2 tagged with green fluorescent protein (GFP) in live infected cells. Together with additional results from indirect immunofluorescence, our studies reveal major morphologic distortion of nuclear-rim LBR and lamins A/C, B1, and B2. By 8 h p.i., we also observed a significant redistribution of LBR-GFP to the endoplasmic reticulum, where it colocalized with a subpopulation of cytoplasmic glycoprotein B by immunofluorescence. In addition, analysis by fluorescence recovery after photobleaching reveals that LBR-GFP exhibited increased diffusional mobility within the nuclear membrane of infected cells. This is consistent with the disruption of interactions between LBR and the underlying lamina. In addition to studying stably expressed GFP-lamins by fluorescence microscopy, we studied endogenous A- and B-type lamins in infected cells by Western blotting. Both approaches reveal a loss of lamins associated with virus infection. These data indicate major disruption of the nuclear envelope and lamina of HSV-1-infected cells and are consistent with a virus-induced dismantling of the nuclear lamina, possibly in order to gain access to the inner nuclear membrane.

scholarly journals Herpes Simplex Virus Type 1 Infection Induces Activation and Recruitment of Protein Kinase C to the Nuclear Membrane and Increased Phosphorylation of Lamin B

2006 ◽  
Vol 80 (1) ◽  
pp. 494-504 ◽  
Author(s):  
Richard Park ◽  
Joel D. Baines
Keyword(s):  
Protein Kinase C ◽  
Herpes Simplex ◽  
Protein Kinase ◽  
Nuclear Membrane ◽  
Nuclear Lamina ◽  
Lamin B ◽  
Kinase C ◽  
Simplex Virus ◽  
Hsv 1

ABSTRACT We report that herpes simplex virus type 1 (HSV-1) infection leads to the recruitment of protein kinase C (PKC) to the nuclear rim. In HEp-2 cells, PKC recruitment to the nuclear rim was initiated between 8 h and 12 h postinfection. PKCδ, a proapoptotic kinase, was completely recruited to the nuclear rim upon infection with HSV-1. PKCα was less dramatically relocalized mostly at the nuclear rim upon infection, although some PKCα remained in the cytoplasm. PKCζ-specific immunofluorescence was not significantly relocated to the nuclear rim. The UL34 and UL31 proteins, as well as their association, were each required for PKC recruitment to the nuclear rim. The HSV-1 US3 protein product, a kinase which regulates the phosphorylation state and localization of UL34, was not required for PKC recruitment to the nuclear rim; however, it was required for proper localization along the nuclear rim, as PKC appeared unevenly distributed along the nuclear rim of cells infected with US3 null and kinase-dead mutants. HSV-1 infection induced the phosphorylation of both lamin B and PKC. Elevated lamin B phosphorylation in HSV-1-infected cells was partially reduced by inhibitors of PKC. The data suggest a model in which kinases that normally disassemble the nuclear lamina during apoptosis are recruited to the nuclear membrane through functions requiring UL31 and UL34. We hypothesize that the recruitment of PKC functions to phosphorylate lamin B to help modify the nuclear lamina and promote budding of nucleocapsids at the inner nuclear membrane.

scholarly journals Herpes Simplex Virus Infection Induces Phosphorylation and Delocalization of Emerin, a Key Inner Nuclear Membrane Protein

2007 ◽  
Vol 81 (9) ◽  
pp. 4429-4437 ◽  
Author(s):  
James B. Morris ◽  
Helmut Hofemeister ◽  
Peter O'Hare
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Nuclear Membrane ◽  
Inner Nuclear Membrane ◽  
Nuclear Egress ◽  
Phosphatase Treatment ◽  
Dna Alterations ◽  
Infected Cells ◽  
Simplex Virus ◽  
Inner Nuclear Membrane Protein

ABSTRACT The inner nuclear membrane (INM) contains specialized membrane proteins that selectively interact with nuclear components including the lamina, chromatin, and DNA. Alterations in the organization of and interactions with INM and lamina components are likely to play important roles in herpesvirus replication and, in particular, exit from the nucleus. Emerin, a member of the LEM domain class of INM proteins, binds a number of nuclear components including lamins, the DNA-bridging protein BAF, and F-actin and is thought to be involved in maintaining nuclear integrity. Here we report that emerin is quantitatively modified during herpes simplex virus (HSV) infection. Modification begins early in infection, involves multiple steps, and is reversed by phosphatase treatment. Emerin phosphorylation during infection involves one or more cellular kinases but can also be influenced by the US3 viral kinase, a protein whose function is known to be involved in HSV nuclear egress. The results from biochemical extraction analyses and from immunofluorescence of the detergent-resistant population demonstrate that emerin association with the INM significantly reduced during infection. We propose that the induction of emerin phosphorylation in infected cells may be involved in nuclear egress and uncoupling interactions with targets such as the lamina, chromatin, or cytoskeletal components.

scholarly journals Conformational Changes in the Nuclear Lamina Induced by Herpes Simplex Virus Type 1 Require Genes UL31 and UL34

2004 ◽  
Vol 78 (11) ◽  
pp. 5564-5575 ◽  
Author(s):  
Ashley E. Reynolds ◽  
Li Liang ◽  
Joel D. Baines
Keyword(s):  
Herpes Simplex ◽  
Conformational Changes ◽  
Nuclear Membrane ◽  
Protein Complex ◽  
Nuclear Lamina ◽  
Lamin A ◽  
Infected Cells ◽  
Simplex Virus

ABSTRACT The herpes simplex virus type 1 (HSV-1) UL31 and UL34 proteins are dependent on each other for proper targeting to the nuclear membrane and are required for efficient envelopment of nucleocapsids at the inner nuclear membrane. In this work, we show that whereas the solubility of lamins A and C (lamin A/C) was not markedly increased, HSV induced conformational changes in the nuclear lamina of infected cells, as viewed after staining with three different lamin A/C-specific antibodies. In one case, reactivity with a monoclonal antibody that recognizes an epitope in the lamin tail domain was greatly reduced in HSV-infected cells. This apparent HSV-induced epitope masking required both UL31 and UL34, but these proteins were not sufficient to mask the epitope in uninfected cells, indicating that other HSV proteins are also required. In the second case, staining with a rabbit polyclonal antibody that primarily recognizes epitopes in the lamin A/C rod domain revealed that UL34 is required for HSV-induced decreased availability of epitopes for reaction with the antibody, whereas UL31 protein was dispensable for this effect. Still another polyclonal antibody indicated virtually no difference in lamin A/C staining in infected versus uninfected cells, indicating that the HSV-induced changes are more conformational than the result of lamin depletion at the nuclear rim. Further evidence supporting an interaction between the nuclear lamina and the UL31/UL34 protein complex includes the observations that (i) overexpression of the UL31 protein in uninfected cells was sufficient to relocalize lamin A/C from the nuclear rim into nucleoplasmic aggregates, (ii) overexpression of UL34 was sufficient to relocalize some lamin A/C into the cytoplasm, and (iii) both UL31 and UL34 could directly bind lamin A/C in vitro. These studies suggest that the UL31 and UL34 proteins modify the conformation of the nuclear lamina in infected cells, possibly by direct interaction with lamin A/C, and that other proteins are also likely involved. Given that the nuclear lamina potentially excludes nucleocapsids from envelopment sites at the inner nuclear membrane, the lamina alteration may reflect a role of the UL31/UL34 protein complex in perturbing the lamina to promote nucleocapsid egress from the nucleus. Alternatively, the data are compatible with a role of the lamina in targeting the UL31/UL34 protein complex to the nuclear membrane.

Lamin B receptor: role on chromatin structure, cellular senescence and possibly aging

2020 ◽  
Vol 477 (14) ◽  
pp. 2715-2720
Author(s):  
Susana Castro-Obregón
Keyword(s):  
Cellular Senescence ◽  
Nuclear Membrane ◽  
Chromatin Structure ◽  
Cholesterol Synthesis ◽  
Reductase Activity ◽  
Chimeric Protein ◽  
Nuclear Lamina ◽  
Lamin B ◽  
Inner Nuclear Membrane ◽  
Lamin B Receptor

The nuclear envelope is composed by an outer nuclear membrane and an inner nuclear membrane, which is underlain by the nuclear lamina that provides the nucleus with mechanical strength for maintaining structure and regulates chromatin organization for modulating gene expression and silencing. A layer of heterochromatin is beneath the nuclear lamina, attached by inner nuclear membrane integral proteins such as Lamin B receptor (LBR). LBR is a chimeric protein, having also a sterol reductase activity with which it contributes to cholesterol synthesis. Lukasova et al. showed that when DNA is damaged by ɣ-radiation in cancer cells, LBR is lost causing chromatin structure changes and promoting cellular senescence. Cellular senescence is characterized by terminal cell cycle arrest and the expression and secretion of various growth factors, cytokines, metalloproteinases, etc., collectively known as senescence-associated secretory phenotype (SASP) that cause chronic inflammation and tumor progression when they persist in the tissue. Therefore, it is fundamental to understand the molecular basis for senescence establishment, maintenance and the regulation of SASP. The work of Lukasova et al. contributed to our understanding of cellular senescence establishment and provided the basis that lead to the further discovery that chromatin changes caused by LBR reduction induce an up-regulated expression of SASP factors. LBR dysfunction has relevance in several diseases and possibly in physiological aging. The potential bifunctional role of LBR on cellular senescence establishment, namely its role in chromatin structure together with its enzymatic activity contributing to cholesterol synthesis, provide a new target to develop potential anti-aging therapies.

scholarly journals Nucleolin Is Required for Efficient Nuclear Egress of Herpes Simplex Virus Type 1 Nucleocapsids

2009 ◽  
Vol 84 (4) ◽  
pp. 2110-2121 ◽  
Author(s):  
Ken Sagou ◽  
Masashi Uema ◽  
Yasushi Kawaguchi
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Nuclear Membrane ◽  
Herpes Simplex Virus Type ◽  
Viral Dna ◽  
Nuclear Egress ◽  
Infected Cells ◽  
Simplex Virus ◽  
Hsv 1

ABSTRACT Herpesvirus nucleocapsids assemble in the nucleus and must cross the nuclear membrane for final assembly and maturation to form infectious progeny virions in the cytoplasm. It has been proposed that nucleocapsids enter the perinuclear space by budding through the inner nuclear membrane, and these enveloped nucleocapsids then fuse with the outer nuclear membrane to enter the cytoplasm. Little is known about the mechanism(s) for nuclear egress of herpesvirus nucleocapsids and, in particular, which, if any, cellular proteins are involved in the nuclear egress pathway. UL12 is an alkaline nuclease encoded by herpes simplex virus type 1 (HSV-1) and has been suggested to be involved in viral DNA maturation and nuclear egress of nucleocapsids. Using a live-cell imaging system to study cells infected by a recombinant HSV-1 expressing UL12 fused to a fluorescent protein, we observed the previously unreported nucleolar localization of UL12 in live infected cells and, using coimmunoprecipitation analyses, showed that UL12 formed a complex with nucleolin, a nucleolus marker, in infected cells. Knockdown of nucleolin in HSV-1-infected cells reduced capsid accumulation, as well as the amount of viral DNA resistant to staphylococcal nuclease in the cytoplasm, which represented encapsidated viral DNA, but had little effect on these viral components in the nucleus. These results indicated that nucleolin is a cellular factor required for efficient nuclear egress of HSV-1 nucleocapsids in infected cells.

scholarly journals Temporal Association of Protamine 1 with the Inner Nuclear Membrane Protein Lamin B Receptor during Spermiogenesis

2003 ◽  
Vol 279 (12) ◽  
pp. 11626-11631 ◽  
Author(s):  
Ilias Mylonis ◽  
Victoria Drosou ◽  
Stefano Brancorsini ◽  
Eleni Nikolakaki ◽  
Paolo Sassone-Corsi ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Nuclear Membrane ◽  
Temporal Association ◽  
Lamin B ◽  
Inner Nuclear Membrane ◽  
Lamin B Receptor ◽  
Inner Nuclear Membrane Protein ◽  
Protamine 1 ◽  
Nuclear Membrane Protein

scholarly journals The Lamin B receptor is essential for cholesterol synthesis and perturbed by disease-causing mutations

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Pei-Ling Tsai ◽  
Chenguang Zhao ◽  
Elizabeth Turner ◽  
Christian Schlieker
Keyword(s):  
Nuclear Membrane ◽  
Cholesterol Synthesis ◽  
Point Mutations ◽  
Nuclear Lamina ◽  
Human Cell Line ◽  
Loss Of Function ◽  
Lamin B ◽  
Inner Nuclear Membrane ◽  
Lamin B Receptor ◽  
Polytopic Membrane Protein

Lamin B receptor (LBR) is a polytopic membrane protein residing in the inner nuclear membrane in association with the nuclear lamina. We demonstrate that human LBR is essential for cholesterol synthesis. LBR mutant derivatives implicated in Greenberg skeletal dysplasia or Pelger-Huët anomaly fail to rescue the cholesterol auxotrophy of a LBR-deficient human cell line, consistent with a loss-of-function mechanism for these congenital disorders. These disease-causing variants fall into two classes: point mutations in the sterol reductase domain perturb enzymatic activity by reducing the affinity for the essential cofactor NADPH, while LBR truncations render the mutant protein metabolically unstable, leading to its rapid degradation at the inner nuclear membrane. Thus, metabolically unstable LBR variants may serve as long-sought-after model substrates enabling previously impossible investigations of poorly understood protein turnover mechanisms at the inner nuclear membrane of higher eukaryotes.

scholarly journals Extragenic Suppression of a Mutation in Herpes Simplex Virus 1 UL34 That Affects Lamina Disruption and Nuclear Egress

2016 ◽  
Vol 90 (23) ◽  
pp. 10738-10751 ◽  
Author(s):  
Amber Vu ◽  
Chelsea Poyzer ◽  
Richard Roller
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Nuclear Membrane ◽  
Nuclear Lamina ◽  
Nuclear Shape ◽  
Lamin A ◽  
Herpes Simplex Virus 1 ◽  
Inner Nuclear Membrane ◽  
Nuclear Egress ◽  
Simplex Virus

ABSTRACT Nuclear egress of herpesviruses is accompanied by changes in the architecture of the nuclear membrane and nuclear lamina that are thought to facilitate capsid access to the inner nuclear membrane (INM) and curvature of patches of the INM around the capsid during budding. Here we report the properties of a point mutant of pUL34 (Q163A) that fails to induce gross changes in nuclear architecture or redistribution of lamin A/C. The UL34(Q163A) mutant shows a roughly 100-fold defect in single-step growth, and it forms small plaques. This mutant has a defect in nuclear egress, and furthermore, it fails to disrupt nuclear shape or cause observable displacement of lamin A/C despite retaining the ability to recruit the pUS3 and PKC protein kinases and to mediate phosphorylation of emerin. Extragenic suppressors of the UL34(Q163A) phenotype were isolated, and all of them carry a single mutation of arginine 229 to leucine in UL31. Surprisingly, although this UL31 mutation largely restores virus replication, it does not correct the lamina disruption defect, suggesting that, in Vero cells, changes in nuclear shape and gross displacements of lamin A/C may facilitate but are unnecessary for nuclear egress. IMPORTANCE Herpesvirus nuclear egress is an essential and conserved process that requires close association of the viral capsid with the inner nuclear membrane and budding of the capsid into that membrane. Access to the nuclear membrane and tight curvature of that membrane are thought to require disruption of the nuclear lamina that underlies the inner nuclear membrane, and consistent with this idea, herpesvirus infection induces biochemical and architectural changes at the nuclear membrane. The significance of the nuclear membrane architectural changes is poorly characterized. The results presented here address that deficiency in our understanding and show that a combination of mutations in two of the viral nuclear egress factors results in a failure to accomplish at least two components of lamina disruption while still allowing relatively efficient viral replication, suggesting that changes in nuclear shape and displacement of lamins are not necessary for herpes simplex virus 1 (HSV-1) nuclear egress.

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