scholarly journals A Lamin a Chimeric Protein Containing a FRET Based Stress Sensors Reports Spatio-Temporal Forces in the Nuclear Lamina

2016 ◽  
Vol 110 (3) ◽  
pp. 23a-24a
Author(s):  
Thomas M. Suchyna ◽  
Fanji Meng ◽  
Frederick Sachs ◽  
Wilma Hofmann
Keyword(s):  
Chimeric Protein ◽  
Nuclear Lamina ◽  
Lamin A ◽  
Stress Sensors ◽  
Spatio Temporal

scholarly journals SUMOylation of RepoMan during late telophase regulates dephosphorylation of lamin A

2021 ◽  
Author(s):  
Takanobu Moriuchi ◽  
Fumiko Hirose
Keyword(s):  
Binding Affinity ◽  
Protein Phosphatase ◽  
Regulatory Mechanism ◽  
Nuclear Lamina ◽  
Regulatory Subunit ◽  
Lamin A ◽  
Temporal Regulation ◽  
Late Telophase ◽  
Spatio Temporal

Dephosphorylation of lamin A, which triggers nuclear lamina reconstitution, is crucial for the completion of mitosis. However, the specific phosphatase and regulatory mechanism that allow timely lamin A dephosphorylation remain unclear. Here, we report that RepoMan, a regulatory subunit of protein phosphatase 1γ (PP1γ) is transiently modified with SUMO-2 at K762 during late telophase. SUMOylation of RepoMan markedly enhanced its binding affinity with lamin A. Moreover, the SUMOylated RepoMan/PP1γ contributes to lamin A recruitment to telophase chromosomes and dephosphorylation of the mitotic lamin A phosphorylation. Expression of a SUMO-2 mutant defective in interaction with SUMO interacting motif (SIM) resulted in failure of the lamin A and RepoMan association, along with abrogation of lamin A dephosphorylation and subsequent nuclear lamina formation. These findings strongly suggested that RepoMan/PP1γ recruits lamin A through SUMO-SIM interaction. Thus, transient SUMOylation of RepoMan plays an important role in the spatio-temporal regulation of lamin A dephosphorylation and the subsequent nuclear lamina formation at the end of mitosis.

scholarly journals Determinants for intracellular sorting of cytoplasmic and nuclear intermediate filaments.

1994 ◽  
Vol 127 (5) ◽  
pp. 1327-1343 ◽  
Author(s):  
M J Monteiro ◽  
C Hicks ◽  
L Gu ◽  
S Janicki
Keyword(s):  
Amino Acid ◽  
Amino Acid Sequence ◽  
Nuclear Localization ◽  
Chimeric Protein ◽  
Nuclear Lamina ◽  
Lamin A ◽  
Head Domain ◽  
Cytoplasmic Filaments ◽  
Caax Motif

The mechanism by which nuclear and cytoplasmic filaments are sorted in vivo was studied by examining which lamin sequences are required to target an otherwise cytoplasmic IF protein, the small neurofilament subunit (NF-L), to the nuclear lamina. By swapping corresponding domains between NF-L and lamin A, nuclear envelope targeting of NF-L was shown to require the presence of the "head" domain, a 42-amino acid sequence unique to lamin rod domains, a nuclear localization signal and the CAAX motif. Replacement of the entire COOH-terminal tail of lamin A with that of NF-L had no discernible effect on nuclear localization of lamin A, provided the substituted NF-L tail contained a NLS and a CAAX motif. This chimeric protein exhibited characteristics more typical of lamin B than that of the parental lamin A. With regard to cytoplasmic assembly properties, substitution of the head domain of lamin A for that of NF-L did not substantially affect the ability of NF-L to coassemble with vimentin in the cytoplasm. In contrast, insertion of a 42-amino acid sequence unique to lamin rod domains into NF-L profoundly affected NF-L coassembly with vimentin indicating that the 42-amino acid insertion in lamins may be important for sorting lamins from cytoplasmic IF proteins.

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 Reduced Lamin A/C does Not Facilitate Cancer Cell Transendothelial Migration but Compromises Lung Metastasis

Cancers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 2383
Author(s):  
Francesco Roncato ◽  
Ofer Regev ◽  
Sara W. Feigelson ◽  
Sandeep Kumar Yadav ◽  
Lukasz Kaczmarczyk ◽  
...  
Keyword(s):  
Cancer Cells ◽  
Lung Metastasis ◽  
Metastatic Cancer ◽  
Nuclear Lamina ◽  
Transendothelial Migration ◽  
Soft Agar ◽  
Lamin A ◽  
And Migration

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.

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

Cells ◽  
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.

scholarly journals Cellular and Animal Models of Striated Muscle Laminopathies

Cells ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 291 ◽  
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.

scholarly journals Physiological and pathological roles of LRRK2 in the nuclear envelope integrity

2019 ◽  
Vol 28 (23) ◽  
pp. 3982-3996 ◽  
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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