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 Lamin C regulates genome organization after mitosis

2020 ◽  
Author(s):  
X Wong ◽  
VE Hoskins ◽  
JC Harr ◽  
M Gordon ◽  
KL Reddy
Keyword(s):  
Genome Organization ◽  
Mammalian Cells ◽  
Regulation Of Gene Expression ◽  
Nuclear Periphery ◽  
Nuclear Lamina ◽  
Lamin A ◽  
3D Genome ◽  
Cellular Processes ◽  
Genomic Regions ◽  
In Cells

AbstractThe dynamic 3D organization of the genome is central to the regulation of gene expression and developmental progression, with its disruption being implicated in various diseases. The nuclear lamina, a proteinaceous meshwork underlying the nuclear envelope (NE), provides both structural and regulatory influences on genome organization through the tethering of large inactive genomic regions, called Lamina Associated Domains (LADs), to the nuclear periphery. Evidence suggests that the A type lamins, lamins A and C, are the predominant lamins involved in the peripheral association of LADs, with these two isotypes forming distinct networks and potentially involved in different cellular processes. Here we tested whether lamins A and C have distinct roles in genome organization by examining chromosome architecture in cells in which lamin C or lamin A are specifically down-regulated. We find that lamin C (not lamin A) is required for the 3D organization of LADs and overall chromosome organization in the cell nucleus. Striking differences in the localization of lamin A and lamin C are present as cells exit mitosis that persist through early G1. Whereas lamin A associates with the nascent NE during telophase, lamin C remains in the interior surrounding nucleoplasmic LAD clusters. 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 consequently global 3D genome organization, is perturbed only in cells depleted of lamin C, and not in cells depleted of lamin A. We conclude that lamin C regulates LAD dynamics after mitosis and is a key regulator of genome organization in mammalian cells. These findings reveal an unexpectedly central role for lamin C in genome organization, including both inter-chromosomal LAD-LAD segregation and LAD scaffolding at the NE.

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 Concentration-dependent lamin assembly and its roles in the localization of other nuclear proteins

2014 ◽  
Vol 25 (8) ◽  
pp. 1287-1297 ◽  
Author(s):  
Yuxuan Guo ◽  
Youngjo Kim ◽  
Takeshi Shimi ◽  
Robert D. Goldman ◽  
Yixian Zheng
Keyword(s):  
Nuclear Lamina ◽  
Nuclear Pore ◽  
Lamin A ◽  
Nuclear Pore Complexes ◽  
Developmental Defects ◽  
Protein Levels ◽  
Lamin B1 ◽  
Mouse Cells ◽  
Pore Complexes ◽  
And Function

The nuclear lamina (NL) consists of lamin polymers and proteins that bind to the polymers. Disruption of NL proteins such as lamin and emerin leads to developmental defects and human diseases. However, the expression of multiple lamins, including lamin-A/C, lamin-B1, and lamin-B2, in mammals has made it difficult to study the assembly and function of the NL. Consequently, it has been unclear whether different lamins depend on one another for proper NL assembly and which NL functions are shared by all lamins or are specific to one lamin. Using mouse cells deleted of all or different combinations of lamins, we demonstrate that the assembly of each lamin into the NL depends primarily on the lamin concentration present in the nucleus. When expressed at sufficiently high levels, each lamin alone can assemble into an evenly organized NL, which is in turn sufficient to ensure the even distribution of the nuclear pore complexes. By contrast, only lamin-A can ensure the localization of emerin within the NL. Thus, when investigating the role of the NL in development and disease, it is critical to determine the protein levels of relevant lamins and the intricate shared or specific lamin functions in the tissue of interest.

scholarly journals Functional correlation of H3K9me2 and nuclear compartment formation

2020 ◽  
Author(s):  
Kei Fukuda ◽  
Chikako Shimura ◽  
Hisashi Miura ◽  
Akie Tanigawa ◽  
Takehiro Suzuki ◽  
...  
Keyword(s):  
Transcriptional Activation ◽  
Genome Organization ◽  
Mammalian Cells ◽  
Embryonic Stem ◽  
Epigenetic Mark ◽  
3 Dimensional ◽  
3D Genome ◽  
Functional Correlation ◽  
Genome Wide

AbstractBackgroundHistone H3 lysine 9 dimethylation (H3K9me2) is a highly conserved silencing epigenetic mark. Chromatin marked with H3K9me2 forms large domains in mammalian cells and correlates well with lamina-associated domains and the B compartment. However, the role of H3K9me2 in 3-dimensional (3D) genome organization remains unclear.ResultsWe investigated the genome-wide H3K9me2 distribution, the transcriptome and 3D genome organization in mouse embryonic stem cells (mESCs) upon the inhibition or depletion of H3K9 methyltransferases (MTases) G9a/GLP, SETDB1, and SUV39H1/2. We found that H3K9me2 is regulated by these five MTases; however, H3K9me2 and transcription in the A and B compartments were largely regulated by different sets of the MTases: H3K9me2 in the A compartments were mainly regulated by G9a/GLP and SETDB1, while H3K9me2 in the B compartments were regulated by all five H3K9 MTases. Furthermore, decreased H3K9me2 correlated with the changes to the more active compartmental state that accompanied transcriptional activation.ConclusionOur data showed that H3K9me2 domain formation is functionally linked to 3D genome organization.

scholarly journals Perturbations in 3D genome organization can promote acquired drug resistance

2021 ◽  
Author(s):  
Anna G Manjón ◽  
Daan Peric Hupkes ◽  
Ning Qing Liu ◽  
Anoek Friskes ◽  
Stacey Joosten ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Drug Resistance ◽  
Genome Organization ◽  
Gene Activation ◽  
Nuclear Lamina ◽  
Tumor Evolution ◽  
Gene Encoding ◽  
Acquired Drug Resistance ◽  
H3k27 Methylation ◽  
3D Genome

AbstractAcquired drug resistance is a major problem in the treatment of cancer. hTERT-immortalized, untransformed RPE-1 (RPE) cells can acquire resistance to taxol by derepressing the ABCB1 gene, encoding for the multidrug transporter P-gP. Here we have investigated how the ABCB1 gene is derepressed. We show that activation of the ABCB1 gene is associated with reduced DNA methylation, reduced H3K9 trimethylation and increased H3K27 acetylation at the ABCB1 promoter. In addition, we find that the ABCB1 locus has moved away from the nuclear lamina in the taxol-resistant cells. This raises the question which of these alterations were causal to derepression. Directly modifying DNA methylation or H3K27 methylation had neither significant effect on ABCB1 expression, nor did it promote drug resistance. In contrast, the disruption of Lamin B Receptor (LBR), a component of the nuclear lamina involved in genome organization, did promote the acquisition of a taxol-resistant phenotype in a subset of cells. Using CRISPRa-mediated gene activation, we could further substantiate a model in which disruption of lamina association renders the ABCB1 gene permissive to derepression. Based on these data we propose a model in which nuclear lamina dissociation of a repressed gene allows for its activation, implying that deregulation of the 3D genome topology could play an important role in tumor evolution and the acquisition of drug resistance.

scholarly journals Genome-wide maps of nucleolus interactions reveal distinct layers of repressive chromatin domains

2020 ◽  
Author(s):  
Cristiana Bersaglieri ◽  
Jelena Kresoja-Rakic ◽  
Shivani Gupta ◽  
Dominik Bär ◽  
Rostyslav Kuzyakiv ◽  
...  
Keyword(s):  
Nuclear Periphery ◽  
Interaction Strength ◽  
Nuclear Lamina ◽  
Nuclear Space ◽  
Chromosome Architecture ◽  
Neural Genes ◽  
Repressive Chromatin ◽  
Genome Wide ◽  
Nuclear Environment

AbstractEukaryotic chromosomes are folded into hierarchical domains, enabling the organization of the genome into functional compartments. Nuclear periphery and nucleolus are two nuclear landmarks thought to contribute to repressive chromosome architecture. However, while the role of nuclear lamina (NL) in genome organization has been well documented, the function of the nucleolus remains under-investigated due to the lack of methods for genome-wide maps of nucleolar associated domains (NADs). Here we established a method based on a Dam-fused engineered nucleolar histone H2B that marks DNA contacting the nucleolus. NAD-maps of ESCs and neural progenitors revealed layers of genome compartmentalization with distinct, repressive chromatin states based on the interaction with the nucleolus, NL, or both. NADs showed higher H3K9me2 and lower H3K27me3 content than regions exclusively interacting with NL. Upon ESC differentiation, chromosomes around the nucleolus acquire a more compact, rigid architecture whereas NADs specific for ESCs decrease their interaction strength within the repressive B-compartment strength, unlocking neural genes from repressive nuclear environment. The methodologies here developed will make possible to include the contribution of the nucleolus in future studies investigating the relationship between nuclear space and genome function.

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 Cohesin-Mediated Genome Architecture Does Not Define DNA Replication Timing Domains

Genes ◽  
2019 ◽  
Vol 10 (3) ◽  
pp. 196 ◽  
Author(s):  
Phoebe Oldach ◽  
Conrad A. Nieduszynski
Keyword(s):  
Dna Replication ◽  
Genome Organization ◽  
Mammalian Cells ◽  
Replication Timing ◽  
S Phase ◽  
Genome Architecture ◽  
3D Genome ◽  
Synchronized Cells ◽  
Dna Replication Timing ◽  
Phase Entry

3D genome organization is strongly predictive of DNA replication timing in mammalian cells. This work tested the extent to which loop-based genome architecture acts as a regulatory unit of replication timing by using an auxin-inducible system for acute cohesin ablation. Cohesin ablation in a population of cells in asynchronous culture was shown not to disrupt patterns of replication timing as assayed by replication sequencing (RepliSeq) or BrdU-focus microscopy. Furthermore, cohesin ablation prior to S phase entry in synchronized cells was similarly shown to not impact replication timing patterns. These results suggest that cohesin-mediated genome architecture is not required for the execution of replication timing patterns in S phase, nor for the establishment of replication timing domains in G1.

Redistribution of nuclear lamin A is an early event associated with differentiation of human promyelocytic leukemia HL-60 cells

1992 ◽  
Vol 101 (3) ◽  
pp. 657-670
Author(s):  
J.F. Collard ◽  
J.L. Senecal ◽  
Y. Raymond
Keyword(s):  
Phorbol Esters ◽  
Nuclear Lamina ◽  
Early Event ◽  
Protein Synthesis Inhibitor ◽  
Lamin A ◽  
Macrophage Phenotype ◽  
Synthesis Inhibitor ◽  
Nuclear Location ◽  
The Individual ◽  
Carboxy Terminal

The nuclear lamina of mammalian somatic cells is characterized by the constitutive presence of lamin B polypeptides while the appearance of lamins A and C generally occur during establishment of a differentiated phenotype. We have used antibodies specific to the unique carboxy-terminal domain of lamin A, i.e. distinct from the shared domains of lamins A and C, to study the individual behaviour of lamin A during establishment of a macrophage phenotype in human HL-60 cells. Lamin A was present as a nuclear cap in the majority of undifferentiated cells and it was redistributed to a full peripheral nuclear location very early after induction of differentiation by phorbol esters, even in the presence of a protein synthesis inhibitor. Induction of the cells into a reversible precommitment state by bromodeoxyuridine was accompanied by a similar redistribution of lamin A that however reverted to a cap after removal of inducer. No changes were observed in the uniform peripheral nuclear location of lamin C under all of these conditions. These results strongly suggest that lamin A plays a role in the early events of cell differentiation. Taken together with previous results on the interaction of A-type lamins with chromatin, these findings offer experimental evidence consistent with the proposed role of A-type lamins, and particularly lamin A, in the process of chromatin reorganization that accompanies the expression of a differentiated phenotype.

Expression of nuclear lamins during mouse preimplantation development

Development ◽  
1988 ◽  
Vol 102 (2) ◽  
pp. 271-278
Author(s):  
E. Houliston ◽  
M.N. Guilly ◽  
J.C. Courvalin ◽  
B. Maro
Keyword(s):  
Cell Differentiation ◽  
Early Development ◽  
Nuclear Periphery ◽  
Preimplantation Development ◽  
Lamin A ◽  
Positive Staining ◽  
Lamin B ◽  
Nuclear Lamins ◽  
Mouse Cells

The expression of nuclear lamins during mouse preimplantation development was studied by immunofluorescence, immunoblotting and immunoprecipitation. Two sera were used, specific either for lamin B or lamins A and C. Both sera gave a positive staining of the nuclear periphery throughout preimplantation development (fertilized eggs to late blastocysts). Immunoblots revealed that the three lamins were present in eggs and blastocysts. However, lamin A from eggs was found to have a higher apparent Mr than lamin A from blastocysts and other mouse cells. Using immunoprecipitation, synthesis of lamin A was detected in eggs while synthesis of lamin B was detected in 8-cell embryos and blastocysts, indicating that at least some of the lamins used during early development do not come from a store in the egg. These results are discussed in relation to the possible role of lamins during cell differentiation.

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