scholarly journals Directed targeting of chromatin to the nuclear lamina is mediated by chromatin state and A-type lamins

2015 ◽  
Vol 208 (1) ◽  
pp. 33-52 ◽  
Author(s):  
Jennifer C. Harr ◽  
Teresa Romeo Luperchio ◽  
Xianrong Wong ◽  
Erez Cohen ◽  
Sarah J. Wheelan ◽  
...  
Keyword(s):  
Binding Sites ◽  
Nuclear Organization ◽  
Insertion Site ◽  
Nuclear Periphery ◽  
Histone H3 ◽  
Nuclear Lamina ◽  
Lamin A ◽  
Developmentally Regulated ◽  
Specific Variable ◽  
Endogenous Loci

Nuclear organization has been implicated in regulating gene activity. Recently, large developmentally regulated regions of the genome dynamically associated with the nuclear lamina have been identified. However, little is known about how these lamina-associated domains (LADs) are directed to the nuclear lamina. We use our tagged chromosomal insertion site system to identify small sequences from borders of fibroblast-specific variable LADs that are sufficient to target these ectopic sites to the nuclear periphery. We identify YY1 (Ying-Yang1) binding sites as enriched in relocating sequences. Knockdown of YY1 or lamin A/C, but not lamin A, led to a loss of lamina association. In addition, targeted recruitment of YY1 proteins facilitated ectopic LAD formation dependent on histone H3 lysine 27 trimethylation and histone H3 lysine di- and trimethylation. Our results also reveal that endogenous loci appear to be dependent on lamin A/C, YY1, H3K27me3, and H3K9me2/3 for maintenance of lamina-proximal positioning.

Abstract 508: Nuclear Lamins At Enhancers: A New Hypothesis for Laminopathies

2020 ◽  
Vol 127 (Suppl_1) ◽  
Author(s):  
Kohta Ikegami ◽  
Stefano Secchia ◽  
Omar Almakki ◽  
Alexis V Stutzman ◽  
Sachie Ikegami ◽  
...  
Keyword(s):  
Gene Expression ◽  
Histone Acetylation ◽  
Binding Sites ◽  
Nuclear Periphery ◽  
Nuclear Lamina ◽  
Lamin A ◽  
New Paradigm ◽  
Control Of Gene Expression ◽  
Nuclear Lamins ◽  
Nuclear Interior

The segregation of heterochromatin domains (LADs) at the nuclear periphery by the nuclear lamina, composed by polymerized nuclear Lamin A/C, provides a longstanding paradigm for the control of gene expression and for the mechanisms underlying Lamin-A/C-associated disorders, including progeria and cardiomyopathy. Here, we provide evidence supporting a novel paradigm that Lamin A/C functions as a transcription factor in the nuclear interior. We discovered that Ser22-phosphorylated Lamin A/C (pS22-Lamin A/C), required for lamin depolymerization during mitosis, populated the nuclear interior throughout the cell cycle. pS22-Lamin A/C ChIP-deq demonstrated localization at a large subset of putative active enhancers, not LADs. pS22-Lamin A/C-binding sites were co-occupied by the transcriptional activator c-Jun. In progeria patient-derived fibroblasts, a subset of pS22-Lamin A/C-binding sites were lost whereas new pS22-Lamin A/C-binding sites emerged. New pS22-Lamin A/C binding was accompanied by increased histone acetylation and increased c-Jun binding, whereas loss of pS22-Lamin A/C-binding was accompanied by loss of histone acetylation and c-Jun binding. New pS22-Lamin A/C enhancer binding in progeria was associated with upregulated expression of genes implicated in progeria pathophysiology, including cardiovascular disease. In contrast, alteration of LADs in progeria-patient cells could not explain the observed gene expression changes. These results suggest that Lamin A/C regulates gene expression by enhancer binding in the nuclear interior, independent of its function at the nuclear lamina, providing a new paradigm for the pathogenesis of lamin-associated disorders. pS22-Lamin A/C was also present in the nuclear interior of adult mouse cardiomyocytes. Cardiomyocyte-specific deletion of Lmna encoding Lamin A/C in adult mice caused extensive transcriptional changes in the heart and dilated cardiomyopathy, without apparent reduction of nuclear peripheral Lamin A/C. Disruption of the gene regulatory rather than LAD tethering function of Lamin A/C may underlie the pathogenesis of disorders caused by LMNA mutations, including cardiomyopathy.

scholarly journals Colocalization of intranuclear lamin foci with RNA splicing factors

1999 ◽  
Vol 112 (24) ◽  
pp. 4651-4661 ◽  
Author(s):  
G. Jagatheesan ◽  
S. Thanumalayan ◽  
B. Muralikrishna ◽  
N. Rangaraj ◽  
A.A. Karande ◽  
...  
Keyword(s):  
Monoclonal Antibody ◽  
Rna Splicing ◽  
Nuclear Periphery ◽  
Nuclear Lamina ◽  
Splicing Factors ◽  
Lamin A ◽  
Lamin B1 ◽  
Differential Reactivity ◽  
Fibrous Network

The lamins form a fibrous network underlying the inner nuclear membrane termed the nuclear lamina. In order to gain insights into the role of lamins in nuclear organization, we have characterized a monoclonal antibody (LA-2H10) raised against recombinant rat lamin A that labels nuclei in a speckled pattern in all cells of unsynchronized populations of HeLa and rat F-111 fibroblast cells, unlike the typical nuclear periphery staining by another monoclonal antibody to lamin A, LA-2B3. In immunolocalization studies the lamin A speckles or foci were found to colocalize with the RNA splicing factors SC-35 and U5-116 kD, but not with p80 coilin found in coiled bodies. Lamin B1 was also associated with these foci. These foci dispersed when cells entered mitosis and reformed during anaphase. The differential reactivity of LA-2H10 and LA-2B3 was retained after nuclei were extracted with detergents, nucleases and salt to disrupt interactions of lamins with chromatin and other nuclear proteins. Using deletion fragments of recombinant lamin A, the epitope recognized by LA-2H10 was located between amino acids 171 and 246. Our findings are consistent with a structural role for lamins in supporting nuclear compartments containing proteins involved in RNA splicing.

scholarly journals Roles of the Nuclear Lamina in Stable Nuclear Association and Assembly of a Herpesviral Transactivator Complex on Viral Immediate-Early Genes

mBio ◽  
2012 ◽  
Vol 3 (1) ◽  
Author(s):  
Lindsey Silva ◽  
Hyung Suk Oh ◽  
Lynne Chang ◽  
Zhipeng Yan ◽  
Steven J. Triezenberg ◽  
...  
Keyword(s):  
Herpes Simplex Virus ◽  
Herpes Simplex ◽  
Viral Genome ◽  
Nuclear Periphery ◽  
Nuclear Lamina ◽  
Immediate Early ◽  
Lamin A ◽  
Wild Type ◽  
Simplex Virus ◽  
Activator Complex

ABSTRACTLittle is known about the mechanisms of gene targeting within the nucleus and its effect on gene expression, but most studies have concluded that genes located near the nuclear periphery are silenced by heterochromatin. In contrast, we found that early herpes simplex virus (HSV) genome complexes localize near the nuclear lamina and that this localization is associated with reduced heterochromatin on the viral genome and increased viral immediate-early (IE) gene transcription. In this study, we examined the mechanism of this effect and found that input virion transactivator protein, virion protein 16 (VP16), targets sites adjacent to the nuclear lamina and is required for targeting of the HSV genome to the nuclear lamina, exclusion of heterochromatin from viral replication compartments, and reduction of heterochromatin on the viral genome. Because cells infected with the VP16 mutant virusin1814 showed a phenotype similar to that of lamin A/C−/−cells infected with wild-type virus, we hypothesized that the nuclear lamina is required for VP16 activator complex formation. In lamin A/C−/−mouse embryo fibroblasts, VP16 and Oct-1 showed reduced association with the viral IE gene promoters, the levels of VP16 and HCF-1 stably associated with the nucleus were lower than in wild-type cells, and the association of VP16 with HCF-1 was also greatly reduced. These results show that the nuclear lamina is required for stable nuclear localization and formation of the VP16 activator complex and provide evidence for the nuclear lamina being the site of assembly of the VP16 activator complex.IMPORTANCEThe targeting of chromosomes in the cell nucleus is thought to be important in the regulation of expression of genes on the chromosomes. The major documented effect of intranuclear targeting has been silencing of chromosomes at sites near the nuclear periphery. In this study, we show that targeting of the herpes simplex virus DNA genome to the nuclear periphery promotes formation of transcriptional activator complexes on the viral genome, demonstrating that the nuclear periphery also has sites for activation of transcription. These results highlight the importance of the nuclear lamina, the structure that lines the inner nuclear membrane, in both transcriptional activation and repression. Future studies defining the molecular structures of these two types of nuclear sites should define new levels of gene regulation.

scholarly journals Deformation of the nucleus by TGFβ1 via the remodeling of nuclear envelope and histone isoforms

2022 ◽  
Vol 15 (1) ◽  
Author(s):  
Ya-Hui Chi ◽  
Wan-Ping Wang ◽  
Ming-Chun Hung ◽  
Gunn-Guang Liou ◽  
Jing-Ya Wang ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Cell Lines ◽  
Nuclear Periphery ◽  
Nuclear Lamina ◽  
Lamin A ◽  
Nuclear Deformation ◽  
Smad Signaling ◽  
Lamin B1 ◽  
Compositional Changes ◽  
Nucleosomal Structure

AbstractThe cause of nuclear shape abnormalities which are often seen in pre-neoplastic and malignant tissues is not clear. In this study we report that deformation of the nucleus can be induced by TGFβ1 stimulation in several cell lines including Huh7. In our results, the upregulated histone H3.3 expression downstream of SMAD signaling contributed to TGFβ1-induced nuclear deformation, a process of which requires incorporation of the nuclear envelope (NE) proteins lamin B1 and SUN1. During this process, the NE constitutively ruptured and reformed. Contrast to lamin B1 which was relatively stationary around the nucleus, the upregulated lamin A was highly mobile, clustering at the nuclear periphery and reintegrating into the nucleoplasm. The chromatin regions that lost NE coverage formed a supra-nucleosomal structure characterized by elevated histone H3K27me3 and histone H1, the formation of which depended on the presence of lamin A. These results provide evidence that shape of the nucleus can be modulated through TGFβ1-induced compositional changes in the chromatin and nuclear lamina.

scholarly journals Deformation of the nucleus by TGFβ1 via the remodeling of nuclear envelope and histone isoforms

2021 ◽  
Author(s):  
Ya-Hui Chi ◽  
Wan-Ping Wang ◽  
Ming-Chun Hung ◽  
Gunn-Guang Liou ◽  
Jing-Ya Wang ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Dna Damage Response ◽  
Nuclear Periphery ◽  
Nuclear Lamina ◽  
Lamin A ◽  
Nuclear Deformation ◽  
Lamin B1 ◽  
Damage Response ◽  
Compositional Changes ◽  
Nucleosomal Structure

Abstract The cause of nuclear shape abnormalities which are often seen in pre-neoplastic and malignant tissues is not clear. In this study we report that deformation of the nucleus can be induced by TGFβ1 stimulation in several cell lines including Huh7. In our results, the upregulated histone H3.3 expression downstream of SMAD signaling contributed to TGFβ1-induced nuclear deformation, a process of which requires incorporation of the nuclear envelope (NE) proteins lamin B1 and SUN1. During this process, the NE constitutively ruptured and reformed with no observable indications of DNA damage response. Contrast to lamin B1 which was relatively stationary around the nucleus, the upregulated lamin A was highly mobile, shuttling between the nucleus and cytoplasm, and clustering at the nuclear periphery. The chromatin regions that lost NE coverage formed a supra-nucleosomal structure characterized by elevated histone H3K27me3 and histone H1, the formation of which depended on the presence of lamin A. These results provide evidence that shape of the nucleus can be modulated through TGFβ1-induced compositional changes in the chromatin and 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 Phosphorylated Lamin A/C in the nuclear interior binds active enhancers associated with abnormal transcription in progeria

2019 ◽  
Author(s):  
Kohta Ikegami ◽  
Stefano Secchia ◽  
Omar Almakki ◽  
Jason D. Lieb ◽  
Ivan P. Moskowitz
Keyword(s):  
Binding Sites ◽  
Human Fibroblasts ◽  
Nuclear Periphery ◽  
Transcriptional Activator ◽  
Premature Aging ◽  
Lamin A ◽  
List Type ◽  
Enhancer Activity ◽  
Nuclear Interior ◽  
Specific Subset

ABSTRACTLMNA encodes nuclear lamin A/C that tethers lamina-associated heterochromatin domains (LADs) to the nuclear periphery. Point mutations in LMNA cause degenerative disorders including the premature aging disorder Hutchinson-Gilford progeria, but the mechanisms are unknown. We report that Ser22-phosphorylated Lamin A/C (pS22-Lamin A/C) was localized to the interior of the nucleus in human fibroblasts throughout the cell cycle. pS22-Lamin A/C interacted with a specific subset of putative active enhancers, not LADs, primarily at locations co-bound by the transcriptional activator c-Jun. In progeria-patient fibroblasts, a subset of pS22-Lamin A/C-binding sites were lost whereas new pS22-Lamin A/C-binding sites emerged in normally quiescent loci. These new pS22-Lamin A/C-binding sites displayed increased histone acetylation and c-Jun binding, implying increased enhancer activity. The genes near these new binding sites, implicated in clinical components of progeria including carotid artery diseases, hypertension, and cardiomegaly, were upregulated in progeria. These results suggest that Lamin A/C regulates gene expression by direct enhancer binding in the nuclear interior. Disruption of the gene regulatory rather than LAD function of Lamin A/C presents a novel mechanism for disorders caused by LMNA mutations including progeria.HIGHLIGHTSpS22-Lamin A/C is present in the nuclear interior throughout interphase.pS22-Lamin A/C associates with active enhancers, not lamina-associated domains.pS22-Lamin A/C-genomic binding sites are co-bound by the transcriptional activator c-Jun.New pS22-Lamin A/C binding in progeria accompanies upregulation of disease-related genes.

scholarly journals Deformation of the nucleus by TGFβ1 via the remodeling of nuclear envelope and histone isoforms

2021 ◽  
Author(s):  
Ya-Hui Chi ◽  
Wan-Ping Wang ◽  
Ming-Chun Hung ◽  
Gunn-Guang Liou ◽  
Jing-Ya Wang ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Dna Damage Response ◽  
Nuclear Periphery ◽  
Nuclear Lamina ◽  
Lamin A ◽  
Nuclear Deformation ◽  
Lamin B1 ◽  
Damage Response ◽  
Compositional Changes ◽  
Nucleosomal Structure

Abstract The cause of nuclear shape abnormalities which are often seen in pre-neoplastic and malignant tissues is not clear. In this study we report that deformation of the nucleus can be induced by TGFb1 stimulation in several cell lines including Huh7. In our results, the upregulated histone H3.3 expression downstream of SMAD signaling contributed to TGFb1-induced nuclear deformation, a process of which requires incorporation of the nuclear envelope (NE) proteins lamin B1 and SUN1. During this process, the NE constitutively ruptured and reformed with no observable indications of DNA damage response. Contrast to lamin B1 which was relatively stationary around the nucleus, the upregulated lamin A was highly mobile, shuttling between the nucleus and cytoplasm, and clustering at the nuclear periphery. The chromatin regions that lost NE coverage formed a supra-nucleosomal structure characterized by elevated histone H3K27me3 and histone H1, the formation of which depended on the presence of lamin A. These results provide evidence that shape of the nucleus can be modulated through TGFb1-induced compositional changes in the chromatin and nuclear lamina.

scholarly journals Lamin C is required to establish genome organization after mitosis

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Xianrong Wong ◽  
Victoria E. Hoskins ◽  
Ashley J. Melendez-Perez ◽  
Jennifer C. Harr ◽  
Molly Gordon ◽  
...  
Keyword(s):  
Genome Organization ◽  
Mammalian Cells ◽  
Nuclear Periphery ◽  
Nuclear Lamina ◽  
Lamin A ◽  
Chromosome Architecture ◽  
3D Genome ◽  
Mouse Cells ◽  
The Individual ◽  
Differential Phosphorylation

Abstract Background The dynamic 3D organization of the genome is central to gene regulation and development. The nuclear lamina influences genome organization through the tethering of lamina-associated domains (LADs) to the nuclear periphery. Evidence suggests that lamins A and C are the predominant lamins involved in the peripheral association of LADs, potentially serving different roles. Results Here, we examine chromosome architecture in mouse cells in which lamin A or lamin C are downregulated. We find that lamin C, and not lamin A, is required for the 3D organization of LADs and overall chromosome organization. Striking differences in localization are present as cells exit mitosis and persist through early G1 and are linked to differential phosphorylation. Whereas lamin A associates with the nascent nuclear envelope (NE) during telophase, lamin C remains in the interior, surrounding globular LAD aggregates enriched on euchromatic regions. Lamin C association with the NE is delayed until several hours into G1 and correlates temporally and spatially with the post-mitotic NE association of LADs. Post-mitotic LAD association with the NE, and global 3D genome organization, is perturbed only in cells depleted of lamin C, and not lamin A. Conclusions Lamin C regulates LAD dynamics during exit from mitosis and is a key regulator of genome organization in mammalian cells. This reveals an unexpectedly central role for lamin C in genome organization, including inter-chromosomal LAD-LAD segregation and LAD scaffolding at the NE, raising intriguing questions about the individual and overlapping roles of lamin A/C in cellular function and disease.

scholarly journals Deformation of the Nucleus by TGFβ1 Via the Remodeling of Nuclear Envelope and Histone Isoforms

2021 ◽  
Author(s):  
Ya-Hui Chi ◽  
Wan-Ping Wang ◽  
Ming-Chun Hung ◽  
Gunn-Guang Liou ◽  
Jing-Ya Wang ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Dna Damage Response ◽  
Nuclear Periphery ◽  
Nuclear Lamina ◽  
Lamin A ◽  
Nuclear Deformation ◽  
Lamin B1 ◽  
Damage Response ◽  
Compositional Changes ◽  
Nucleosomal Structure

Abstract The cause of nuclear shape abnormalities which are often seen in pre-neoplastic and malignant tissues is not clear. In this study we report that deformation of the nucleus can be induced by TGFb1 stimulation in several cell lines including Huh7. In our results, the upregulated histone H3.3 expression downstream of SMAD signaling contributed to TGFb1-induced nuclear deformation, a process of which requires incorporation of the nuclear envelope (NE) proteins lamin B1 and SUN1. During this process, the NE constitutively ruptured and reformed with no observable indications of DNA damage response. Contrast to lamin B1 which was relatively stationary around the nucleus, the upregulated lamin A was highly mobile, shuttling between the nucleus and cytoplasm, and clustering at the nuclear periphery. The chromatin regions that lost NE coverage formed a supra-nucleosomal structure characterized by elevated histone H3K27me3 and histone H1, the formation of which depended on the presence of lamin A. These results provide evidence that shape of the nucleus can be modulated through TGFb1-induced compositional changes in the chromatin and nuclear lamina.

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