Differential basal-to-apical accessibility of lamin A/C epitopes in the nuclear lamina regulated by changes in cytoskeletal tension

The mechanisms by which the nuclear lamina of tumor cells influences tumor growth and migration are highly disputed. Lamin A and its variant lamin C are key lamina proteins that control nucleus stiffness and chromatin conformation. Downregulation of lamin A/C in two prototypic metastatic lines, B16F10 melanoma and E0771 breast carcinoma, facilitated cell squeezing through rigid pores, and reduced heterochromatin content. Surprisingly, both lamin A/C knockdown cells grew poorly in 3D spheroids within soft agar, and lamin A/C deficient cells derived from spheroids transcribed lower levels of the growth regulator Yap1. Unexpectedly, the transendothelial migration of both cancer cells in vitro and in vivo, through lung capillaries, was not elevated by lamin A/C knockdown and their metastasis in lungs was even dramatically reduced. Our results are the first indication that reduced lamin A/C content in distinct types of highly metastatic cancer cells does not elevate their transendothelial migration (TEM) capacity and diapedesis through lung vessels but can compromise lung metastasis at a post extravasation level.

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

Molecular Biology of the Cell ◽

10.1091/mbc.e13-11-0644 ◽

2014 ◽

Vol 25 (8) ◽

pp. 1287-1297 ◽

Cited By ~ 39

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.

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PCAF Involvement in Lamin A/C-HDAC2 Interplay during the Early Phase of Muscle Differentiation

Cells ◽

10.3390/cells9071735 ◽

2020 ◽

Vol 9 (7) ◽

pp. 1735

Author(s):

Spartaco Santi ◽

Vittoria Cenni ◽

Cristina Capanni ◽

Giovanna Lattanzi ◽

Elisabetta Mattioli

Keyword(s):

Muscular Dystrophy ◽

Early Phase ◽

Myogenic Differentiation ◽

Nuclear Lamina ◽

Muscle Differentiation ◽

Lamin A ◽

Histone Deacetylase 2 ◽

Muscle Gene Expression ◽

Muscle Gene ◽

Human Muscle Cells

Lamin A/C has been implicated in the epigenetic regulation of muscle gene expression through dynamic interaction with chromatin domains and epigenetic enzymes. We previously showed that lamin A/C interacts with histone deacetylase 2 (HDAC2). In this study, we deepened the relevance and regulation of lamin A/C-HDAC2 interaction in human muscle cells. We present evidence that HDAC2 binding to lamin A/C is related to HDAC2 acetylation on lysine 75 and expression of p300-CBP associated factor (PCAF), an acetyltransferase known to acetylate HDAC2. Our findings show that lamin A and farnesylated prelamin A promote PCAF recruitment to the nuclear lamina and lamin A/C binding in human myoblasts committed to myogenic differentiation, while protein interaction is decreased in differentiating myotubes. Interestingly, PCAF translocation to the nuclear envelope, as well as lamin A/C-PCAF interaction, are reduced by transient expression of lamin A mutated forms causing Emery Dreifuss muscular dystrophy. Consistent with this observation, lamin A/C interaction with both PCAF and HDAC2 is significantly reduced in Emery–Dreifuss muscular dystrophy myoblasts. Overall, these results support the view that, by recruiting PCAF and HDAC2 in a molecular platform, lamin A/C might contribute to regulate their epigenetic activity required in the early phase of muscle differentiation.

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Cellular and Animal Models of Striated Muscle Laminopathies

Cells ◽

10.3390/cells8040291 ◽

2019 ◽

Vol 8 (4) ◽

pp. 291 ◽

Cited By ~ 3

Author(s):

Hannah A. Nicolas ◽

Marie-Andrée Akimenko ◽

Frédérique Tesson

Keyword(s):

Skeletal Muscle ◽

Skeletal Muscles ◽

Molecular Mechanisms ◽

Striated Muscle ◽

Nuclear Lamina ◽

The Other ◽

Lamin A ◽

Lmna Gene ◽

Future Directions ◽

Exon 10

The lamin A/C (LMNA) gene codes for nuclear intermediate filaments constitutive of the nuclear lamina. LMNA has 12 exons and alternative splicing of exon 10 results in two major isoforms—lamins A and C. Mutations found throughout the LMNA gene cause a group of diseases collectively known as laminopathies, of which the type, diversity, penetrance and severity of phenotypes can vary from one individual to the other, even between individuals carrying the same mutation. The majority of the laminopathies affect cardiac and/or skeletal muscles. The underlying molecular mechanisms contributing to such tissue-specific phenotypes caused by mutations in a ubiquitously expressed gene are not yet well elucidated. This review will explore the different phenotypes observed in established models of striated muscle laminopathies and their respective contributions to advancing our understanding of cardiac and skeletal muscle-related laminopathies. Potential future directions for developing effective treatments for patients with lamin A/C mutation-associated cardiac and/or skeletal muscle conditions will be discussed.

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Physiological and pathological roles of LRRK2 in the nuclear envelope integrity

Human Molecular Genetics ◽

10.1093/hmg/ddz245 ◽

2019 ◽

Vol 28 (23) ◽

pp. 3982-3996 ◽

Cited By ~ 3

Author(s):

Vered Shani ◽

Hazem Safory ◽

Raymonde Szargel ◽

Ninghan Wang ◽

Tsipora Cohen ◽

...

Keyword(s):

Nuclear Envelope ◽

Cortical Neurons ◽

Nuclear Lamina ◽

Lamin A ◽

Loss Of Function ◽

Function Mechanism ◽

Disease Mutations ◽

Lrrk2 G2019s ◽

Sporadic Parkinson’S Disease ◽

Seven In Absentia

Abstract Mutations in LRRK2 cause autosomal dominant and sporadic Parkinson’s disease, but the mechanisms involved in LRRK2 toxicity in PD are yet to be fully understood. We found that LRRK2 translocates to the nucleus by binding to seven in absentia homolog (SIAH-1), and in the nucleus it directly interacts with lamin A/C, independent of its kinase activity. LRRK2 knockdown caused nuclear lamina abnormalities and nuclear disruption. LRRK2 disease mutations mostly abolish the interaction with lamin A/C and, similar to LRRK2 knockdown, cause disorganization of lamin A/C and leakage of nuclear proteins. Dopaminergic neurons of LRRK2 G2019S transgenic and LRRK2 −/− mice display decreased circularity of the nuclear lamina and leakage of the nuclear protein 53BP1 to the cytosol. Dopaminergic nigral and cortical neurons of both LRRK2 G2019S and idiopathic PD patients exhibit abnormalities of the nuclear lamina. Our data indicate that LRRK2 plays an essential role in maintaining nuclear envelope integrity. Disruption of this function by disease mutations suggests a novel phosphorylation-independent loss-of-function mechanism that may synergize with other neurotoxic effects caused by LRRK2 mutations.

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Nucleoplasmic localization of prelamin A: Implications for prenylation-dependent lamin A assembly into the nuclear lamina

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.89.12.5699a ◽

1992 ◽

Vol 89 (12) ◽

pp. 5699-5699

Keyword(s):

Nuclear Lamina ◽

Lamin A ◽

Prelamin A

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

Journal of Histochemistry & Cytochemistry ◽

10.1369/jhc.4a6478.2005 ◽

2005 ◽

Vol 53 (4) ◽

pp. 497-507 ◽

Cited By ~ 17

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.

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Prelamin A-mediated nuclear envelope dynamics in normal and laminopathic cells

Biochemical Society Transactions ◽

10.1042/bst20110657 ◽

2011 ◽

Vol 39 (6) ◽

pp. 1698-1704 ◽

Cited By ~ 19

Author(s):

Giovanna Lattanzi

Keyword(s):

Nuclear Envelope ◽

Accelerated Aging ◽

Nuclear Lamina ◽

Major Constituent ◽

Lamin A ◽

Post Translational Modifications ◽

Prelamin A ◽

Chromatin Dynamics ◽

Chromatin Arrangement ◽

And Function

Prelamin A is the precursor protein of lamin A, a major constituent of the nuclear lamina in higher eukaryotes. Increasing attention to prelamin A processing and function has been given after the discovery, from 2002 to 2004, of diseases caused by prelamin A accumulation. These diseases, belonging to the group of laminopathies and mostly featuring LMNA mutations, are characterized, at the clinical level, by different degrees of accelerated aging, and adipose tissue, skin and bone abnormalities. The outcome of studies conducted in the last few years consists of three major findings. First, prelamin A is processed at different rates under physiological conditions depending on the differentiation state of the cell. This means that, for instance, in muscle cells, prelamin A itself plays a biological role, besides production of mature lamin A. Secondly, prelamin A post-translational modifications give rise to different processing intermediates, which elicit different effects in the nucleus, mostly by modification of the chromatin arrangement. Thirdly, there is a threshold of toxicity, especially of the farnesylated form of prelamin A, whose accumulation is obviously linked to cell and organism senescence. The present review is focused on prelamin A-mediated nuclear envelope modifications that are upstream of chromatin dynamics and gene expression mechanisms regulated by the lamin A precursor.

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