scholarly journals The PRR14 heterochromatin tether encodes modular domains that mediate and regulate nuclear lamina targeting

2019 ◽  
Author(s):  
Kelly L. Dunlevy ◽  
Valentina Medvedeva ◽  
Jade E. Wilson ◽  
Mohammed Hoque ◽  
Trinity Pellegrin ◽  
...  
Keyword(s):  
Nuclear Membrane ◽  
Large Fraction ◽  
Nuclear Periphery ◽  
Nuclear Lamina ◽  
Binding Domain ◽  
Recognition Site ◽  
Evolutionarily Conserved ◽  
Engineering Strategy ◽  
Necessary And Sufficient ◽  
Modular Domains

AbstractA large fraction of epigenetically silent heterochromatin is anchored to the nuclear periphery via “tethering proteins” that function to bridge heterochromatin and the nuclear membrane or nuclear lamina. We identified previously a human tethering protein, PRR14, that binds heterochromatin through an N-terminal domain, but the mechanism and regulation of nuclear lamina association remained to be investigated. Here we identify a centrally located, evolutionarily conserved PRR14 nuclear lamina binding domain (LBD) that is both necessary and sufficient for positioning of PRR14 at the nuclear lamina. We also show that PRR14 associates dynamically with the nuclear lamina, and provide evidence that such dynamics are regulated through phosphorylation of the LBD. We also show that the evolutionary conserved PRR14 C-terminal Tantalus domain encodes a PP2A phosphatase recognition site that regulates PRR14 nuclear lamina association. The overall findings demonstrate a heterochromatin anchoring mechanism whereby the PRR14 tether simultaneously binds heterochromatin and the nuclear lamina through two modular domains. Furthermore, the identification of a modular LBD may provide an engineering strategy for delivery of cargo to the nuclear lamina.

Lamin proteins form an internal nucleoskeleton as well as a peripheral lamina in human cells

1995 ◽  
Vol 108 (2) ◽  
pp. 635-644 ◽  
Author(s):  
P. Hozak ◽  
A.M. Sasseville ◽  
Y. Raymond ◽  
P.R. Cook
Keyword(s):  
Nuclear Membrane ◽  
Intermediate Filament ◽  
Mammalian Cells ◽  
Nuclear Periphery ◽  
Nuclear Lamina ◽  
Human Cells ◽  
Lamin A ◽  
Intermediate Filament Proteins ◽  
Form Part ◽  
Dense Chromatin

The nuclear lamina forms a protein mesh that underlies the nuclear membrane. In most mammalian cells it contains the intermediate filament proteins, lamins A, B and C. As their name indicates, lamins are generally thought to be confined to the nuclear periphery. We now show that they also form part of a diffuse skeleton that ramifies throughout the interior of the nucleus. Unlike their peripheral counterparts, these internal lamins are buried in dense chromatin and so are inaccessible to antibodies, but accessibility can be increased by removing chromatin. Knobs and nodes on an internal skeleton can then be immunolabelled using fluorescein- or gold-conjugated anti-lamin A antibodies. These results suggest that the lamins are misnamed as they are also found internally.

scholarly journals Mena regulates the LINC complex to control actin–nuclear lamina associations, trans-nuclear membrane signalling and cancer gene expression

2021 ◽  
Author(s):  
Frederic Li Mow Chee ◽  
Bruno Beernaert ◽  
Alexander E P Loftus ◽  
Yatendra Kumar ◽  
Billie G C Griffith ◽  
...  
Keyword(s):  
Gene Expression ◽  
Nuclear Envelope ◽  
Cancer Progression ◽  
Nuclear Membrane ◽  
Regulatory Protein ◽  
Nuclear Periphery ◽  
Nuclear Lamina ◽  
Actin Binding ◽  
Cancer Gene ◽  
Linc Complex

Interactions between cells and the extracellular matrix, mediated by integrin adhesion complexes (IACs), play key roles in cancer progression and metastasis. We investigated systems-level changes in the integrin adhesome during metastatic progression of a patient-derived cutaneous squamous cell carcinoma (cSCC), and found that the actin regulatory protein Mena is enriched in IACs in metastatic cSCC cells. Mena is connected within a subnetwork of actin-binding proteins to the LINC complex component nesprin-2, with which it interacts and co-localises at the nuclear envelope of metastatic cells. Moreover, Mena potentiates the interactions of nesprin-2 with the actin cytoskeleton and the nuclear lamina. CRISPR-mediated Mena depletion causes altered nuclear morphology, reduces tyrosine phosphorylation of the nuclear membrane protein emerin and downregulates expression of the immunomodulatory gene PTX3 via the recruitment of its enhancer to the nuclear periphery. We have uncovered an unexpected novel role for Mena at the nuclear membrane, where it controls the LINC complex, nuclear architecture, chromatin repositioning and cancer gene expression. This is the first description of an adhesion protein regulating gene transcription via direct signalling across the nuclear envelope.

scholarly journals Mapping the micro-proteome of the nuclear lamina and lamina-associated domains

2021 ◽  
Vol 4 (5) ◽  
pp. e202000774
Author(s):  
Xianrong Wong ◽  
Jevon A Cutler ◽  
Victoria E Hoskins ◽  
Molly Gordon ◽  
Anil K Madugundu ◽  
...  
Keyword(s):  
Large Fraction ◽  
Nuclear Periphery ◽  
Nuclear Lamina ◽  
Mammalian Genome ◽  
Live Cells ◽  
H3k9 Methylation ◽  
Tracer System ◽  
Membrane Bound ◽  
Gene Regulatory ◽  
Regulatory Functions

The nuclear lamina is a proteinaceous network of filaments that provide both structural and gene regulatory functions by tethering proteins and large domains of DNA, the so-called lamina-associated domains (LADs), to the periphery of the nucleus. LADs are a large fraction of the mammalian genome that are repressed, in part, by their association to the nuclear periphery. The genesis and maintenance of LADs is poorly understood as are the proteins that participate in these functions. In an effort to identify proteins that reside at the nuclear periphery and potentially interact with LADs, we have taken a two-pronged approach. First, we have undertaken an interactome analysis of the inner nuclear membrane bound LAP2β to further characterize the nuclear lamina proteome. To accomplish this, we have leveraged the BioID system, which previously has been successfully used to characterize the nuclear lamina proteome. Second, we have established a system to identify proteins that bind to LADs by developing a chromatin-directed BioID system. We combined the BioID system with the m6A-tracer system which binds to LADs in live cells to identify both LAD proximal and nuclear lamina proteins. In combining these datasets, we have further characterized the protein network at the nuclear lamina, identified putative LAD proximal proteins and found several proteins that appear to interface with both micro-proteomes. Importantly, several proteins essential for LAD function, including heterochromatin regulating proteins related to H3K9 methylation, were identified in this study.

scholarly journals Protein sequestration at the nuclear periphery as a potential regulatory mechanism in premature aging

2017 ◽  
Vol 217 (1) ◽  
pp. 21-37 ◽  
Author(s):  
Leonid Serebryannyy ◽  
Tom Misteli
Keyword(s):  
Nuclear Membrane ◽  
Aging Process ◽  
Regulatory Mechanism ◽  
Biological Process ◽  
Nuclear Periphery ◽  
Nuclear Lamina ◽  
Premature Aging ◽  
Molecular Changes ◽  
Fundamental Biological Process ◽  
Premature Aging Syndrome

Despite the extensive description of numerous molecular changes associated with aging, insights into the driver mechanisms of this fundamental biological process are limited. Based on observations in the premature aging syndrome Hutchinson–Gilford progeria, we explore the possibility that protein regulation at the inner nuclear membrane and the nuclear lamina contributes to the aging process. In support, sequestration of nucleoplasmic proteins to the periphery impacts cell stemness, the response to cytotoxicity, proliferation, changes in chromatin state, and telomere stability. These observations point to the nuclear periphery as a central regulator of the aging phenotype.

scholarly journals Mapping the micro-proteome of the nuclear lamina and lamin associated domains

2019 ◽  
Author(s):  
Jevon A. Cutler ◽  
Xianrong Wong ◽  
Victoria E. Hoskins ◽  
Molly Gordon ◽  
Anil K. Madugundu ◽  
...  
Keyword(s):  
Large Fraction ◽  
Nuclear Periphery ◽  
Nuclear Lamina ◽  
Mammalian Genome ◽  
Live Cells ◽  
H3k9 Methylation ◽  
Tracer System ◽  
Membrane Bound ◽  
Gene Regulatory ◽  
Regulatory Functions

AbstractThe nuclear lamina is a proteinaceous network of filaments that provide both structural and gene regulatory functions by tethering proteins and large domains of DNA, so-called lamin associated domains (LADs), to the periphery of the nucleus. LADs are a large fraction of the mammalian genome that are repressed, in part, by their association to the nuclear periphery. The genesis and maintenance of LADs is poorly understood as are the proteins that participate in these functions. In an effort to identify proteins that reside at the nuclear periphery and potentially interact with LADs, we have taken a two-pronged approach. First, we have undertaken an interactome analysis of the inner nuclear membrane bound LAP2β to further characterize the nuclear lamina proteome. To accomplish this, we have leveraged the BioID system, which previously has been successfully used to characterize the nuclear lamina proteome. Second, we have established a system to identify proteins that bind to LADs by developing a chromatin directed BioID system. We combined the BioID system with the m6A-tracer system which binds to LADs in live cells to identify both LAD proximal and nuclear lamina proteins. In combining these datasets, we have further characterized the protein network at the nuclear lamina, identified putative LAD proximal proteins and found several proteins that appear to interface with both micro-proteomes. Importantly, several proteins essential for LAD function, including heterochromatin regulating proteins related to H3K9 methylation, were identified in this study.

scholarly journals Identification of new transmembrane proteins concentrated at the nuclear envelope using organellar proteomics of mesenchymal cells

2018 ◽  
Author(s):  
Li-Chun Cheng ◽  
Sabyasachi Baboo ◽  
Cory Lindsay ◽  
Liza Brusman ◽  
Salvador Martinez-Bartolomé ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Nuclear Periphery ◽  
Transmembrane Proteins ◽  
Nuclear Lamina ◽  
Cell Types ◽  
Nucleocytoplasmic Transport ◽  
Membrane Dynamics ◽  
Nuclear Pore ◽  
Nuclear Pore Complexes

AbstractThe nuclear envelope (NE) is an endoplasmic reticulum (ER) subdomain that contains characteristic components dedicated to nuclear functions. These include nuclear pore complexes (NPCs) – the channels for nucleocytoplasmic transport, and the nuclear lamina (NL) – a scaffold for NE and chromatin organization at the nuclear periphery. Since numerous human diseases associated with NE/NL proteins occur in mesenchyme-derived cells, a more comprehensive characterization of proteins concentrated at the NE in these cell types is warranted. Accordingly, we used proteomics to analyze NE and other subcellular fractions isolated from mesenchymal stem cells and from differentiated adipocytes and myocytes. We evaluated the proteomics datasets to calculate relative protein enrichment in the NE fraction, using a spectral abundance-based scoring system that accurately described most benchmark proteins. We then examined five high-scoring transmembrane proteins expressed in all three cell types that were not previously known to be enriched at the NE. Using quantitative immunofluorescence microscopy to track ectopically expressed proteins, we validated that all five of these components are substantially concentrated at the NE of multiple cell types. One (Itprip) is exposed to the outer nuclear membrane, a second (Smpd4) is enriched at the NPC, and the three others (Mfsd10, Tmx4, and Arl6ip6) are suggested to reside in the inner nuclear membrane. Considering their sequences and other features, these proteins provide new focal points for studying the functions and membrane dynamics of the NE. Our datasets should be useful for identifying additional NE-concentrated proteins, and for evaluating candidates that are identified in screening.

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 Lamin B1 acetylation slows the G1 to S cell cycle transition through inhibition of DNA repair

2021 ◽  
Author(s):  
Laura A Murray-Nerger ◽  
Joshua L Justice ◽  
Pranav Rekapalli ◽  
Josiah E Hutton ◽  
Ileana M Cristea
Keyword(s):  
Cell Cycle ◽  
Dna Repair ◽  
Posttranslational Modifications ◽  
Cell Cycle Progression ◽  
Nuclear Periphery ◽  
Virus Production ◽  
Nuclear Lamina ◽  
Regulatory Function ◽  
Herpesvirus Type ◽  
Lamin B1

Abstract The integrity and regulation of the nuclear lamina is essential for nuclear organization and chromatin stability, with its dysregulation being linked to laminopathy diseases and cancer. Although numerous posttranslational modifications have been identified on lamins, few have been ascribed a regulatory function. Here, we establish that lamin B1 (LMNB1) acetylation at K134 is a molecular toggle that controls nuclear periphery stability, cell cycle progression, and DNA repair. LMNB1 acetylation prevents lamina disruption during herpesvirus type 1 (HSV-1) infection, thereby inhibiting virus production. We also demonstrate the broad impact of this site on laminar processes in uninfected cells. LMNB1 acetylation negatively regulates canonical nonhomologous end joining by impairing the recruitment of 53BP1 to damaged DNA. This defect causes a delay in DNA damage resolution and a persistent activation of the G1/S checkpoint. Altogether, we reveal LMNB1 acetylation as a mechanism for controlling DNA repair pathway choice and stabilizing the nuclear periphery.

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