The Nuclear Membrane and Mechanotransduction: Impaired Nuclear Mechanics and Mechanotransduction in Lamin A/C Deficient Cells

2008 ◽  
pp. 264-278 ◽  
Author(s):  
Jan Lammerding ◽  
Richard T. Lee
Keyword(s):  
Nuclear Membrane ◽  
Lamin A ◽  
Nuclear Mechanics

scholarly journals Emerin Represses STAT3 Signaling through Nuclear Membrane-Based Spatial Control

2021 ◽  
Vol 22 (13) ◽  
pp. 6669
Author(s):  
Byongsun Lee ◽  
Seungjae Lee ◽  
Younggwang Lee ◽  
Yongjin Park ◽  
Jaekyung Shim
Keyword(s):  
Muscular Dystrophy ◽  
Nuclear Membrane ◽  
Target Genes ◽  
Janus Kinase ◽  
C2c12 Cells ◽  
Specific Gene ◽  
Lamin A ◽  
Stat3 Signaling ◽  
Exact Function ◽  
Muscle Homeostasis

Emerin is the inner nuclear membrane protein involved in maintaining the mechanical integrity of the nuclear membrane. Mutations in EMD encoding emerin cause Emery-Dreifuss muscular dystrophy (EDMD). There has been accumulating evidence that emerin regulation of specific gene expression is associated with this disease, but the exact function of emerin has still less revealing. Here, we have shown that emerin downregulates signal transducers and activators of transcription 3 (STAT3) signaling, activated exclusively by Janus-kinase (JAK). Deletion mutation experiments showed that the lamin-binding domain of emerin is essential for the inhibition of STAT3 signaling. Emerin interacted directly and co-localized with STAT3 in the nuclear membrane. Emerin knockdown induced STAT3 target genes Bcl2 and Survivin to increase cell survival signals and suppress hydrogen peroxide-induced cell death in HeLa cells. Specifically, downregulation of BAF or lamin A/C increases STAT3 signaling, suggesting that correct-localized emerin by assembling with BAF and lamin A/C acts as an intrinsic inhibitor against STAT3 signaling. In C2C12 cells, emerin knockdown induced STAT3 target gene, Pax7, and activated abnormal myoblast proliferation associated with muscle wasting in skeletal muscle homeostasis. Our results indicate that emerin downregulates STAT3 signaling by inducing retention of STAT3 and delaying STAT3 signaling in the nuclear membrane. This mechanism provides clues to the etiology of emerin-related muscular dystrophy and could be a new therapeutic target for treatment.

scholarly journals A pathway linking oxidative stress and the Ran GTPase system in progeria

2014 ◽  
Vol 25 (8) ◽  
pp. 1202-1215 ◽  
Author(s):  
Sutirtha Datta ◽  
Chelsi J. Snow ◽  
Bryce M. Paschal
Keyword(s):  
Oxidative Stress ◽  
Nuclear Membrane ◽  
Nucleocytoplasmic Transport ◽  
Lamin A ◽  
Mutant Form ◽  
Ran Gtpase ◽  
Nuclear Levels ◽  
Progeria Syndrome ◽  
Hutchinson Gilford Progeria Syndrome ◽  
The Relationship

Maintaining the Ran GTPase at a proper concentration in the nucleus is important for nucleocytoplasmic transport. Previously we found that nuclear levels of Ran are reduced in cells from patients with Hutchinson–Gilford progeria syndrome (HGPS), a disease caused by constitutive attachment of a mutant form of lamin A (termed progerin) to the nuclear membrane. Here we explore the relationship between progerin, the Ran GTPase, and oxidative stress. Stable attachment of progerin to the nuclear membrane disrupts the Ran gradient and results in cytoplasmic localization of Ubc9, a Ran-dependent import cargo. Ran and Ubc9 disruption can be induced reversibly with H2O2. CHO cells preadapted to oxidative stress resist the effects of progerin on Ran and Ubc9. Given that HGPS-patient fibroblasts display elevated ROS, these data suggest that progerin inhibits nuclear transport via oxidative stress. A drug that inhibits pre–lamin A cleavage mimics the effects of progerin by disrupting the Ran gradient, but the effects on Ran are observed before a substantial ROS increase. Moreover, reducing the nuclear concentration of Ran is sufficient to induce ROS irrespective of progerin. We speculate that oxidative stress caused by progerin may occur upstream or downstream of Ran, depending on the cell type and physiological setting.

scholarly journals The fates of chicken nuclear lamin proteins during mitosis: evidence for a reversible redistribution of lamin B2 between inner nuclear membrane and elements of the endoplasmic reticulum.

1988 ◽  
Vol 107 (2) ◽  
pp. 397-406 ◽  
Author(s):  
R Stick ◽  
B Angres ◽  
C F Lehner ◽  
E A Nigg
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Membrane ◽  
Membrane Vesicles ◽  
Soluble Form ◽  
Lamin A ◽  
Cell Fractionation ◽  
Lamin B ◽  
Inner Nuclear Membrane ◽  
Nuclear Lamin ◽  
Mitotic Cells

In chicken, three structurally distinct nuclear lamin proteins have been described. According to their migration on two-dimensional gels, these proteins have been designated as lamins A, B1, and B2. To investigate the functional relationship between chicken lamins and their mammalian counterparts, we have examined here the state of individual chicken lamin proteins during mitosis. Current models proposing functional specializations of mammalian lamin subtypes are in fact largely based on the observation that during mitosis mammalian lamin B remains associated with membrane vesicles, whereas lamins A and C become freely soluble. Cell fractionation experiments combined with immunoblotting show that during mitosis both chicken lamins B1 and B2 remain associated with membranes, whereas lamin A exists in a soluble form. In situ immunoelectron microscopy carried out on mitotic cells also reveals membrane association of lamin B2, whereas the distribution of lamin A is random. From these results we conclude that both chicken lamins B1 and B2 may functionally resemble mammalian lamin B. Interestingly, immunolabeling of mitotic cells revealed an association of lamin B2 with extended membrane cisternae that resembled elements of the endoplasmic reticulum. Quantitatively, we found that all large endoplasmic reticulum-like membranes present in metaphase cells were decorated with lamin B2-specific antibodies. Given that labeling of these mitotic membranes was lower than labeling of interphase nuclear envelopes, it appears likely that during mitotic disassembly and reassembly of the nuclear envelope lamin B2 may reversibly distribute between the inner nuclear membrane and the endoplasmic reticulum.

scholarly journals Visualization of the Nuclear Lamina in Mouse Anterior Pituitary Cells and Immunocytochemical Detection of Lamin A/C by Quick-freeze Freeze-substitution Electron Microscopy

2005 ◽  
Vol 53 (4) ◽  
pp. 497-507 ◽  
Author(s):  
Takao Senda ◽  
Akiko Iizuka-Kogo ◽  
Atsushi Shimomura
Keyword(s):  
Electron Microscopy ◽  
Nuclear Membrane ◽  
Anterior Pituitary ◽  
Freeze Substitution ◽  
Nuclear Lamina ◽  
Immunogold Electron Microscopy ◽  
Lamin A ◽  
Pituitary Cells ◽  
Inner Nuclear Membrane ◽  
Anterior Pituitary Cells

We examined the nuclear lamina in the quickly frozen anterior pituitary cells by electron microscopic techniques combined with freeze substitution, deep etching, and immunocytochemistry and compared it with that in the chemically fixed cells. By quick-freeze freeze-substitution electron microscopy, an electron-lucent layer, as thick as 20 nm, was revealed just inside the inner nuclear membrane, whereas in the conventionally glutaraldehyde-fixed cells the layer was not seen. By quick-freeze deep-etch electron microscopy, we could not distinguish definitively the layer corresponding to the nuclear lamina in either fresh unfixed or glutaraldehyde-fixed cells. Immunofluorescence microscopy showed that lamin A/C in the nucleus was detected in the acetone-fixed cells and briefly in paraformaldehyde-fixed cells but not in the cells with prolonged paraformaldehyde fixation. Nuclear localization of lamin A/C was revealed by immunogold electron microscopy also in the quickly frozen and freeze-substituted cells, but not in the paraformaldehyde-fixed cells. Lamin A/C was localized mainly in the peripheral nucleoplasm within 60 nm from the inner nuclear membrane, which corresponded to the nuclear lamina. These results suggest that the nuclear lamina can be preserved both ultrastructurally and immunocytochemically by quick-freezing fixation, rather than by conventional chemical fixation.

scholarly journals Effects of Lamin A/C, Lamin B1, and Viral US3 Kinase Activity on Viral Infectivity, Virion Egress, and the Targeting of Herpes Simplex Virus UL34-Encoded Protein to the Inner Nuclear Membrane

2008 ◽  
Vol 82 (16) ◽  
pp. 8094-8104 ◽  
Author(s):  
Fan Mou ◽  
Elizabeth G. Wills ◽  
Richard Park ◽  
Joel D. Baines
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Viral Replication ◽  
Nuclear Membrane ◽  
Kinase Activity ◽  
Lamin A ◽  
Viral Infectivity ◽  
Wild Type ◽  
Lamin B1 ◽  
Simplex Virus

ABSTRACT Previous results indicated that the UL34 protein (pUL34) of herpes simplex virus 1 (HSV-1) is targeted to the nuclear membrane and is essential for nuclear egress of nucleocapsids. The normal localization of pUL34 and virions requires the US3-encoded kinase that phosphorylates UL34 and lamin A/C. Moreover, pUL34 was shown to interact with lamin A in vitro. In the present study, glutathione S-transferase/pUL34 was shown to specifically pull down lamin A and lamin B1 from cellular lysates. To determine the role of these interactions on viral infectivity and pUL34 targeting to the inner nuclear membrane (INM), the localization of pUL34 was determined in LmnA−/− and LmnB1−/− mouse embryonic fibroblasts (MEFs) by indirect immunofluorescence and immunogold electron microscopy in the presence or absence of US3 kinase activity. While pUL34 INM targeting was not affected by the absence of lamin B1 in MEFs infected with wild-type HSV as viewed by indirect immunofluorescence, it localized in densely staining scalloped-shaped distortions of the nuclear membrane in lamin B1 knockout cells infected with a US3 kinase-dead virus. Lamin B1 knockout cells were relatively less permissive for viral replication than wild-type MEFs, with viral titers decreased at least 10-fold. The absence of lamin A (i) caused clustering of pUL34 in the nuclear rim of cells infected with wild-type virus, (ii) produced extensions of the INM bearing pUL34 protein in cells infected with a US3 kinase-dead mutant, (iii) precluded accumulation of virions in the perinuclear space of cells infected with this mutant, and (iv) partially restored replication of this virus. The latter observation suggests that lamin A normally impedes viral infectivity and that US3 kinase activity partially alleviates this impediment. On the other hand, lamin B1 is necessary for optimal viral replication, probably through its well-documented effects on many cellular pathways. Finally, neither lamin A nor B1 was absolutely required for targeting pUL34 to the INM, suggesting that this targeting is mediated by redundant functions or can be mediated by other proteins.

scholarly journals Hepatitis C Virus Alters Nuclear Mechanics by Down-Regulating Lamin A/C

2018 ◽  
Vol 114 (3) ◽  
pp. 324a-325a
Author(s):  
Sreenath Balakrishnan ◽  
M.S. Suma ◽  
Geetika Sharma ◽  
Saumitra Das ◽  
G.K. Ananthasuresh
Keyword(s):  
Hepatitis C Virus ◽  
Hepatitis C ◽  
Lamin A ◽  
Nuclear Mechanics

scholarly journals Human Adenovirus Type 5 Infection Leads to Nuclear Envelope Destabilization and Membrane Permeability Independently of Adenovirus Death Protein

2021 ◽  
Vol 22 (23) ◽  
pp. 13034
Author(s):  
Søren Pfitzner ◽  
Jens B. Bosse ◽  
Helga Hofmann-Sieber ◽  
Felix Flomm ◽  
Rudolph Reimer ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Nuclear Envelope ◽  
Membrane Permeability ◽  
Nuclear Membrane ◽  
Membrane Damage ◽  
Human Adenovirus ◽  
Adenovirus Type ◽  
Lamin A ◽  
Infected Cells ◽  
Adenovirus Type 5

The human adenovirus type 5 (HAdV5) infects epithelial cells of the upper and lower respiratory tract. The virus causes lysis of infected cells and thus enables spread of progeny virions to neighboring cells for the next round of infection. The mechanism of adenovirus virion egress across the nuclear barrier is not known. The human adenovirus death protein (ADP) facilitates the release of virions from infected cells and has been hypothesized to cause membrane damage. Here, we set out to answer whether ADP does indeed increase nuclear membrane damage. We analyzed the nuclear envelope morphology using a combination of fluorescence and state-of-the-art electron microscopy techniques, including serial block-face scanning electron microscopy and electron cryo-tomography of focused ion beam-milled cells. We report multiple destabilization phenotypes of the nuclear envelope in HAdV5 infection. These include reduction of lamin A/C at the nuclear envelope, large-scale membrane invaginations, alterations in double membrane separation distance and small-scale membrane protrusions. Additionally, we measured increased nuclear membrane permeability and detected nuclear envelope lesions under cryoconditions. Unexpectedly, and in contrast to previous hypotheses, ADP did not have an effect on lamin A/C reduction or nuclear permeability.

scholarly journals SUN2 Modulates HIV-1 Infection and Latency through Association with Lamin A/C To Maintain the Repressive Chromatin

mBio ◽  
2018 ◽  
Vol 9 (3) ◽  
Author(s):  
Wei-Wei Sun ◽  
Shi Jiao ◽  
Li Sun ◽  
Zhaocai Zhou ◽  
Xia Jin ◽  
...  
Keyword(s):  
Membrane Protein ◽  
Nuclear Membrane ◽  
Active Form ◽  
Lamin A ◽  
Viral Transcription ◽  
Inner Nuclear Membrane ◽  
Proviral Dna ◽  
Repressive Chromatin ◽  
Inner Nuclear Membrane Protein ◽  
Hiv 1

ABSTRACTThe postintegrational latency of HIV-1 is characterized by reversible silencing of long terminal repeat (LTR)-driven transcription of the HIV genome. It is known that the formation of repressive chromatin at the 5′-LTR of HIV-1 proviral DNA impedes viral transcription by blocking the recruitment of positive transcription factors. How the repressive chromatin is formed and modulated during HIV-1 infection remains elusive. Elucidation of which chromatin reassembly factor mediates the reorganization of chromatin is likely to facilitate the understanding of the host’s modulation of HIV-1 transcription and latency. Here we revealed that “Sad1 and UNC84 domain containing 2” (SUN2), an inner nuclear membrane protein, maintained the repressive chromatin and inhibited HIV LTR-driven transcription of proviral DNA through an association with lamin A/C. Specifically, lamin A/C tethered SUN2 to the nucleosomes 1 and 2 of the HIV-1 5′-LTR to block the initiation and elongation of HIV-1 transcription. SUN2 knockdown converted chromatin to an active form and thus enhanced the phosphorylation of RNA polymerase II and its recruitment to the 5′-LTR HIV-1 proviral DNA, leading to reactivation of HIV-1 from latency. Conversely, the exogenous factors such as tumor necrosis factor alpha (TNF-α) induced reactivation, and the replication of HIV-1 led to the disassociation between SUN2 and lamin A/C, suggesting that disruption of the association between SUN2 and lamin A/C to convert the repressive chromatin to the active form might be a prerequisite for the initiation of HIV-1 transcription and replication. Together, our findings indicate that SUN2 is a novel chromatin reassembly factor that helps to maintain chromatin in a repressive state and consequently inhibits HIV-1 transcription.IMPORTANCEDespite the successful use of scores of antiretroviral drugs, HIV latency poses a major impediment to virus eradication. Elucidation of the mechanism of latency facilitates the discovery of new therapeutic strategies. It has been known that the formation of repressive chromatin at the 5′-LTR of HIV-1 proviral DNA impedes viral transcription and maintains viral latency, but how the repressive chromatin is formed and modulated during HIV-1 infection remains elusive. In this study, we performed in-depth virological and cell biological studies and discovered that an inner nuclear membrane protein, SUN2, is a novel chromatin reassembly factor that maintains repressive chromatin and thus modulates HIV-1 transcription and latency: therefore, targeting SUN2 may lead to new strategies for HIV cure.

scholarly journals Lamin A/C and the Immune System: One Intermediate Filament, Many Faces

2020 ◽  
Vol 21 (17) ◽  
pp. 6109
Author(s):  
Angela Saez ◽  
Beatriz Herrero-Fernandez ◽  
Raquel Gomez-Bris ◽  
Beatriz Somovilla-Crespo ◽  
Cristina Rius ◽  
...  
Keyword(s):  
T Cells ◽  
Immune System ◽  
Adaptive Immunity ◽  
Immune Cells ◽  
Cell Cycle Progression ◽  
Cell Types ◽  
Lamin A ◽  
Nuclear Mechanics ◽  
Adaptive Immune Cells ◽  
C Proteins

Nuclear envelope lamin A/C proteins are a major component of the mammalian nuclear lamina, a dense fibrous protein meshwork located in the nuclear interior. Lamin A/C proteins regulate nuclear mechanics and structure and control cellular signaling, gene transcription, epigenetic regulation, cell cycle progression, cell differentiation, and cell migration. The immune system is composed of the innate and adaptive branches. Innate immunity is mediated by myeloid cells such as neutrophils, macrophages, and dendritic cells. These cells produce a rapid and nonspecific response through phagocytosis, cytokine production, and complement activation, as well as activating adaptive immunity. Specific adaptive immunity is activated by antigen presentation by antigen presenting cells (APCs) and the cytokine microenvironment, and is mainly mediated by the cellular functions of T cells and the production of antibodies by B cells. Unlike most cell types, immune cells regulate their lamin A/C protein expression relatively rapidly to exert their functions, with expression increasing in macrophages, reducing in neutrophils, and increasing transiently in T cells. In this review, we discuss and summarize studies that have addressed the role played by lamin A/C in the functions of innate and adaptive immune cells in the context of human inflammatory and autoimmune diseases, pathogen infections, and cancer.

scholarly journals Cellular p32 Is a Critical Regulator of Porcine Circovirus Type 2 Nuclear Egress

2019 ◽  
Vol 93 (23) ◽  
Author(s):  
Tongtong Wang ◽  
Qian Du ◽  
Yingying Niu ◽  
Xiaohua Zhang ◽  
Zhenyu Wang ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Nuclear Membrane ◽  
Nuclear Lamina ◽  
Porcine Circovirus Type ◽  
Porcine Circovirus Type 2 ◽  
Porcine Circovirus ◽  
Lamin A ◽  
Nuclear Egress ◽  
Kinase C

ABSTRACT Circoviruses are the smallest DNA viruses known to infect mammalian and avian species. Although circoviruses are known to be associated with a range of clinical diseases, the details of circovirus DNA release still remain unknown. Here, we identified p32 as a key regulator for porcine circoviral nuclear egress. Upon porcine circovirus type 2 (PCV2) infection, p32 was recruited into the nucleus by the viral capsid (Cap) protein; simultaneously, protein kinase C isoform δ (PKC-δ) was phosphorylated at threonine 505 by phospholipase C (PLC)-mediated signaling at the early stage of infection, which was further amplified by Jun N-terminal protein kinase (JNK) and extracellular signal-regulated kinase (ERK) signaling at the late infection phase. p32 functioned as an adaptor to recruit phosphorylated PKC-δ and Cap to the nuclear membrane to phosphorylate lamin A/C, resulting in a rearrangement of nuclear lamina and thus facilitating viral nuclear egress. Consistent with these findings, knockout (KO) of p32 in PCV2-infected cells markedly reduced the phosphorylation of PKC-δ and impeded the recruitment of p-PKC-δ and Cap to the nuclear membrane, hence abolishing the phosphorylation of lamin A/C and the rearrangement of nuclear lamina. As a result, p32 depletion profoundly impaired the production of cell-free viruses during PCV2 infection. We further identified the N-terminal 24RRR26 of Cap to be crucial for binding to p32, and mutation of these three arginine residues significantly weakened the replication and pathogenesis of PCV2 in vivo. In summary, our findings highlight a critical role of p32 in the activation and recruitment of PKC-δ to phosphorylate lamin A/C and facilitate porcine circoviral nuclear egress, and they certainly help understanding of the mechanism of PCV2 replication. IMPORTANCE Circovirus infections are highly prevalent in mammalian and avian species. Circoviral capsid protein is the only structural protein of the virion that plays an essential role in viral assembly. However, the machinery of circovirus nuclear egress is currently unknown. In this work, we identified p32 as a key regulator of porcine circovirus type 2 (PCV2) nuclear egress that forms a complex with the viral capsid (Cap) protein to enhance protein kinase C isoform δ (PKC-δ) activity; this resulted in a recruitment of phosphorylated PKC-δ to the nuclear membrane, which further phosphorylates lamin A/C to promote the rearrangement of nuclear lamina and facilitate viral nuclear egress. Notably, we found that the N-terminal 24RRR26 of Cap, a highly conserved motif among circovirus species, was required for interacting with p32, and that mutation of this motif markedly impeded PCV2 nuclear egress. These data indicate that p32 is a critical regulator of PCV2 nuclear egress and reveal the importance of this finding in circovirus replication.

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