Alteration of nuclear lamina protein in human fibroblasts infected with cytomegalovirus (HCMV)

Radsak, K.; Schneider, Dominik; Jost, Erich; K, Brücher

doi:10.1007/bf01311120

Cited by 14 publications

(13 citation statements)

References 21 publications

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“…These data corroborate the studies of Radsak and colleagues demonstrating that HSV-1 infection does not induce altered electrophoretic mobilities of lamins in human fibroblast cells infected with wild-type HSV-1 (22,23).…”

Section: Downloaded Fromsupporting

confidence: 90%

Conformational Changes in the Nuclear Lamina Induced by Herpes Simplex Virus Type 1 Require Genes U _L 31 and U _L 34

Reynolds

Liang

Baines

2004

J Virol

159

209

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The herpes simplex virus type 1 (HSV-1) U L 31 and U L 34 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 U L 31 and U L 34, 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 U L 34 is required for HSV-induced decreased availability of epitopes for reaction with the antibody, whereas U L 31 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 HSVinduced 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 U L 31/U L 34 protein complex includes the observations that (i) overexpression of the U L 31 protein in uninfected cells was sufficient to relocalize lamin A/C from the nuclear rim into nucleoplasmic aggregates, (ii) overexpression of U L 34 was sufficient to relocalize some lamin A/C into the cytoplasm, and (iii) both U L 31 and U L 34 could directly bind lamin A/C in vitro. These studies suggest that the U L 31 and U L 34 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 U L 31/U L 34 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 U L 31/U L 34 protein complex to the nuclear membrane.The nuclear envelope consists of two leaflets, defined as the inner nuclear membrane and outer nuclear membrane. The perinuclear space, defined as the space between the two leaflets, is continuous with the lumen of the endoplasmic reticulum. A network of predominantly insoluble cellular proteins, the nuclear lamina, lines the nucleoplasmic face of the inner nuclear membrane. The nuclear lamina provides structural support for the nuclear membrane and attachment sites for chromatin. It is also required for a variety of essential cellular functions, including nuclear assembly following mi...

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Section: Downloaded Fromsupporting

confidence: 90%

Conformational Changes in the Nuclear Lamina Induced by Herpes Simplex Virus Type 1 Require Genes U _L 31 and U _L 34

Reynolds

Liang

Baines

2004

J Virol

159

209

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“…1E, top panels). The loss of immunoreactivity of lamin A (which is not caused by proteolysis) is a late event during the course of HCMV replication as described previously by Radsak et al (24). In our analysis, a general alteration in the amount of cellular protein in virus-infected cells could be excluded by the control staining of constant levels of ␤-actin Fig.…”

Section: Pul97 Induces Alterations In the Subnuclear Localization Patsupporting

confidence: 79%

“…Structural destabilization of the nuclear lamina is generally mediated through phosphorylation of nuclear lamins (2). In HCMV-infected cells, alterations of the nuclear lamina were described (24,44); however, the identity of protein kinases involved in lamin phosphorylation has remained speculative so far. Our data provide evidence for the recruitment of a virus-encoded protein kinase to the nuclear lamina.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, we searched for further phosphorylated cellular targets of pUL97, especially those associated with the nuclear lamina. Depolymerization of the nuclear lamina is a typical feature of herpesvirus infections (1,5,24) as well as cellular mitosis (3,4,27). In both cases, phosphorylation of lamins is an important trigger of the remodeling process.…”

Section: P32 Interacts With the Lamin B Receptor In Human Cells And Rmentioning

confidence: 99%

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Cellular p32 Recruits Cytomegalovirus Kinase pUL97 to Redistribute the Nuclear Lamina

Marschall

Marzi

Siepen

et al. 2005

Journal of Biological Chemistry

163

286

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Replication of human cytomegalovirus is limited at the level of nucleocytoplasmic transport of viral capsids, a process that requires the disassembly of the nuclear lamina. Deletion of the protein kinase gene UL97 from the viral genome showed that the activity of pUL97 plays an important role for viral capsid egress. Here, we report that p32, a novel cellular interactor of the viral kinase pUL97, promotes the accumulation of pUL97 at the nuclear membrane by recruiting the p32-pUL97 complex to the lamin B receptor. Transfection of active pUL97, but not a catalytically inactive mutant, induced a redistribution of lamina components as demonstrated for recombinant lamin B receptor-green fluorescent protein and endogenous lamins A and C. Consistent with this, p32 itself and lamins were phosphorylated by pUL97. Importantly, overexpression of p32 in human cytomegalovirus-infected cells resulted in increased efficiency of viral replication and release of viral particles. Thus, it is highly suggestive that the cellular protein p32 recruits pUL97 to induce a dissolution of the nuclear lamina thereby facilitating the nuclear export of viral capsids.The transport of macromolecules in eukaryotic cells is subject to a strict compartmentalization into nucleus and cytoplasm. Exchange reactions between the two compartments are mediated through the nuclear pore complex, and thus the integrity of the nuclear envelope, composed of membrane and lamina constituents, is crucial for intracellular transport pathways. The nuclear lamina, underlining the inner nuclear membrane, contains a variable number of lamin isoforms (which are members of the intermediate filament family of cytoskeletal proteins) and forms a rigid, proteinaceous meshwork. During infection with herpesviruses, the nuclear lamina represents a barrier to the nucleocytoplasmic transport of viral capsids (1). Because of the large size of herpesviral capsids (ϳ120 nm), which does not allow their direct cytoplasmic release through nuclear pores, the structural destabilization of the nuclear lamina is an important prerequisite of virus budding. Lamina destabilization requires site-specific phosphorylation of lamins and lamin-binding membrane proteins. Phosphorylation leads to lamin depolymerization and may also permit their release from lamin-binding membrane proteins, including the lamin B receptor (LBR) 2 (2, 3). Protein kinase C and Cdc2 have been identified as kinases phosphorylating lamins during mitosis (3, 4). Interestingly, protein kinase C is involved in the dissolution of the nuclear lamina in cells infected with murine cytomegalovirus (5). In addition to cellular protein kinases, the activity of virus-encoded protein kinases has been suspected as an important additional critical factor for nuclear export of herpesviruses, such as herpes simplex virus type 1 (HSV-1) and pseudorabies virus (6, 7). Concerning the replication of human cytomegalovirus (HCMV), which is a major human pathogenic herpesvirus, little information has been published on destabilization of the n...

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“…The main components of the nuclear lamina are the lamins, which, based on their expression patterns, properties and location, can be divided into two main classes: A-type lamins, including lamin A, AD10, C and C2; and B-type lamins, including lamin B1, B2 and B3 (Broers et al, 1997(Broers et al, , 2006Rzepecki, 2002;Stuurman et al, 1998). Several studies have shown that herpesvirus infection causes structural and biochemical rearrangements of nuclear lamina components, to ensure the efficient production of viral progeny (Leach et al, 2007;Marschall et al, 2005;Morris et al, 2007;Mou et al, 2007;Muranyi et al, 2002;Radsak et al, 1989;Reynolds et al, 2004;Scott & O'Hare, 2001). Notably, murine cytomegalovirus (MCMV) and, more recently, herpes simplex virus type 1 (HSV-1) have been reported to recruit cellular protein kinases C (PKCs) at the nuclear rim, and, as a consequence, induce an increase in phosphorylation of nuclear envelope proteins, including lamins and emerin, to promote nuclear lamina dissolution (Leach et al, 2007;Morris et al, 2007;Muranyi et al, 2002;Park & Baines, 2006).…”

Section: Introductionmentioning

confidence: 99%

Remodelling of the nuclear lamina during human cytomegalovirus infection: role of the viral proteins pUL50 and pUL53

Camozzi

Pignatelli

Valvo

et al. 2008

Journal of General Virology

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A fundamental step in the efficient production of human cytomegalovirus (HCMV) progeny is viral egress from the nucleus to the cytoplasm of infected cells. In the family Herpesviridae, this process involves alteration of nuclear lamina components by two highly conserved proteins, whose homologues in HCMV are named pUL50 and pUL53. This study showed that HCMV infection induced the mislocalization of nuclear lamins and that pUL50 and pUL53 play a role in this event. At late stages of infection, both lamin A/C and lamin B showed an irregular distribution on the nuclear rim, coincident with areas of pUL53 accumulation. No variations in the total amount of nuclear lamins could be detected, supporting the view that HCMV induces a qualitative, rather than a quantitative, alteration of these cellular components, as has been suggested previously for other herpesviruses. Interestingly, pUL53, in the absence of other viral products, localized diffusely in the nucleus, whilst the co-expression and interaction of pUL53 with its partner, pUL50, restored its nuclear rim localization in distinct patches, thus indicating that pUL50 is sufficient to induce the localization of pUL53 observed during virus infection. Importantly, analysis of the nuclear lamina in the presence of pUL50-pUL53 complexes at the nuclear boundary and in the absence of other viral products showed that the two viral proteins were sufficient to promote alterations of lamins, strongly resembling those observed during HCMV infection. These results suggest that pUL50 and pUL53 may play an important role in the exit of virions from the nucleus by inducing structural modifications of the nuclear lamina. INTRODUCTIONWhilst herpesvirus genome packaging and capsid formation occur in the nuclear compartment, all subsequent steps of maturation take place in the cytoplasm, the final site of viral particle assembly. The most widely accepted model for herpesvirus nuclear egress suggests that capsids leave the nucleus through budding events at the nuclear envelope (Mettenleiter, 2004;Mettenleiter et al., 2006;Severi et al., 1988;Skepper et al., 2001;Stackpole, 1969), which consists of two leaflets, the inner and the outer nuclear membrane (INM and ONM, respectively) separated by the perinuclear space; nuclear capsids acquire a temporary envelope at the INM, which is subsequently lost by fusion with the ONM, allowing access to the cytosol. However, before crossing the nuclear envelope, virions have to overcome a massive obstacle underlying the INM, represented by the nuclear lamina, a thick meshwork of proteins associating in a highly organized structure. The main components of the nuclear lamina are the lamins, which, based on their expression patterns, properties and location, can be divided into two main classes: A-type lamins, including lamin A, AD10, C and C2; and B-type lamins, including lamin B1, B2 and B3 (Broers et al., 1997(Broers et al., , 2006Rzepecki, 2002;Stuurman et al., 1998). Several studies have shown that herpesvirus infection causes structural and bioch...

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Alteration of nuclear lamina protein in human fibroblasts infected with cytomegalovirus (HCMV)

Cited by 14 publications

References 21 publications

Conformational Changes in the Nuclear Lamina Induced by Herpes Simplex Virus Type 1 Require Genes U _L 31 and U _L 34

Conformational Changes in the Nuclear Lamina Induced by Herpes Simplex Virus Type 1 Require Genes U _L 31 and U _L 34

Cellular p32 Recruits Cytomegalovirus Kinase pUL97 to Redistribute the Nuclear Lamina

Remodelling of the nuclear lamina during human cytomegalovirus infection: role of the viral proteins pUL50 and pUL53

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Alteration of nuclear lamina protein in human fibroblasts infected with cytomegalovirus (HCMV)

Cited by 14 publications

References 21 publications

Conformational Changes in the Nuclear Lamina Induced by Herpes Simplex Virus Type 1 Require Genes U L 31 and U L 34

Conformational Changes in the Nuclear Lamina Induced by Herpes Simplex Virus Type 1 Require Genes U L 31 and U L 34

Cellular p32 Recruits Cytomegalovirus Kinase pUL97 to Redistribute the Nuclear Lamina

Remodelling of the nuclear lamina during human cytomegalovirus infection: role of the viral proteins pUL50 and pUL53

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Conformational Changes in the Nuclear Lamina Induced by Herpes Simplex Virus Type 1 Require Genes U _L 31 and U _L 34

Conformational Changes in the Nuclear Lamina Induced by Herpes Simplex Virus Type 1 Require Genes U _L 31 and U _L 34