Lamin microaggregates lead to altered mechanotransmission in progerin-expressing cells.
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ABSTRACT:
SUBMITTER: Danielsson BE
PROVIDER: S-EPMC7529416 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Mutations in the A-type lamins A and C, two major components of the nuclear lamina, cause a large group of phenotypically diverse diseases collectively referred to as laminopathies. These conditions often involve defects in chromatin organization. However, it is unclear whether A-type lamins interact with chromatin in vivo and whether aberrant chromatin-lamin interactions contribute to disease. Here, we have used an unbiased approach to comparatively map genome-wide interactions of gene promoters with lamin A and progerin, the mutated lamin A isoform responsible for the premature aging disorder Hutchinson-Gilford progeria syndrome (HGPS) in mouse cardiac myoytes and embryonic fibroblasts. We find that lamin A-associated genes are predominantly transcriptionally silent and that loss of lamin association leads to the relocation of peripherally localized genes, but not necessarily to their activation. We demonstrate that progerin induces global changes in chromatin organization by enhancing interactions with a specific subset of genes in addition to the identified lamin A-associated genes. These observations demonstrate disease-related changes in higher order genome organization in HGPS and provide novel insights into the role of lamin-chromatin interactions in chromatin organization.
| S-EPMC3443488 | biostudies-literature
Project description:The nuclear morphology of eukaryotic cells is determined by the interplay between the lamina forming the nuclear skeleton, the chromatin inside the nucleus, and the coupling with the cytoskeleton. Nuclear alterations are often associated with pathological conditions as in Hutchinson-Gilford progeria syndrome, in which a mutation in the lamin A gene yields an altered form of the protein, named progerin, and an aberrant nuclear shape. Here, we introduce an inducible cellular model of Hutchinson-Gilford progeria syndrome in HeLa cells in which increased progerin expression leads to alterations in the coupling of the lamin shell with cytoskeletal or chromatin tethers as well as with polycomb group proteins. Furthermore, our experiments show that progerin expression leads to enhanced nuclear shape fluctuations in response to cytoskeletal activity. To interpret the experimental results, we introduce a computational model of the cell nucleus that explicitly includes chromatin fibers, the nuclear shell, and coupling with the cytoskeleton. The model allows us to investigate how the geometrical organization of the chromatin-lamin tether affects nuclear morphology and shape fluctuations. In sum, our findings highlight the crucial role played by lamin-chromatin and lamin-cytoskeletal alterations in determining nuclear shape morphology and in affecting cellular functions and gene regulation.
| S-EPMC7203074 | biostudies-literature
Project description:The nuclear lamina is an interconnected meshwork of intermediate filament proteins underlying the nuclear envelope. The lamina is an important regulator of nuclear structural integrity as well as nuclear processes, including transcription, DNA replication and chromatin remodeling. The major components of the lamina are A- and B-type lamins. Mutations in lamins impair lamina functions and cause a set of highly tissue-specific diseases collectively referred to as laminopathies. The phenotypic diversity amongst laminopathies is hypothesized to be caused by mutations affecting specific protein interactions, possibly in a tissue-specific manner. Current technologies to identify interaction partners of lamin A and its mutants are hampered by the insoluble nature of lamina components. To overcome the limitations of current technologies, we developed and applied a novel, unbiased approach to identify lamin A-interacting proteins. This approach involves expression of the high-affinity OneSTrEP-tag, precipitation of lamin-protein complexes after reversible protein cross-linking and subsequent protein identification by mass spectrometry. We used this approach to identify in mouse embryonic fibroblasts and cardiac myocyte NklTAg cell lines proteins that interact with lamin A and its mutant isoform progerin, which causes the premature aging disorder Hutchinson-Gilford progeria syndrome (HGPS). We identified a total of 313 lamina-interacting proteins, including several novel lamin A interactors, and we characterize a set of 35 proteins which preferentially interact with lamin A or progerin.
| S-EPMC3027055 | biostudies-literature
Project description:BackgroundHutchinson-Gilford progeria syndrome (HGPS) is a rare disorder characterized by premature aging and death mainly because of myocardial infarction, stroke, or heart failure. The disease is provoked by progerin, a variant of lamin A expressed in most differentiated cells. Patients look healthy at birth, and symptoms typically emerge in the first or second year of life. Assessing the reversibility of progerin-induced damage and the relative contribution of specific cell types is critical to determining the potential benefits of late treatment and to developing new therapies.MethodsWe used CRISPR-Cas9 technology to generate LmnaHGPSrev/HGPSrev (HGPSrev) mice engineered to ubiquitously express progerin while lacking lamin A and allowing progerin suppression and lamin A restoration in a time- and cell type-specific manner on Cre recombinase activation. We characterized the phenotype of HGPSrev mice and crossed them with Cre transgenic lines to assess the effects of suppressing progerin and restoring lamin A ubiquitously at different disease stages as well as specifically in vascular smooth muscle cells and cardiomyocytes.ResultsLike patients with HGPS, HGPSrev mice appear healthy at birth and progressively develop HGPS symptoms, including failure to thrive, lipodystrophy, vascular smooth muscle cell loss, vascular fibrosis, electrocardiographic anomalies, and precocious death (median lifespan of 15 months versus 26 months in wild-type controls, P<0.0001). Ubiquitous progerin suppression and lamin A restoration significantly extended lifespan when induced in 6-month-old mildly symptomatic mice and even in severely ill animals aged 13 months, although the benefit was much more pronounced on early intervention (84.5% lifespan extension in mildly symptomatic mice, P<0.0001, and 6.7% in severely ill mice, P<0.01). It is remarkable that major vascular alterations were prevented and lifespan normalized in HGPSrev mice when progerin suppression and lamin A restoration were restricted to vascular smooth muscle cells and cardiomyocytes.ConclusionsHGPSrev mice constitute a new experimental model for advancing knowledge of HGPS. Our findings suggest that it is never too late to treat HGPS, although benefit is much more pronounced when progerin is targeted in mice with mild symptoms. Despite the broad expression pattern of progerin and its deleterious effects in many organs, restricting its suppression to vascular smooth muscle cells and cardiomyocytes is sufficient to prevent vascular disease and normalize lifespan.
| S-EPMC8614561 | biostudies-literature
Project description:Lamin A is a major component of the lamina, which creates a dynamic network underneath the nuclear envelope. Mutations in the lamin A gene (LMNA) cause severe genetic disorders, one of which is Hutchinson-Gilford progeria syndrome (HGPS), a disease triggered by a dominant mutant named progerin. Unlike the wild-type lamin A, whose farnesylated C-terminus is excised during post-translational processing, progerin retains its farnesyl tail and accumulates on the nuclear membrane, resulting in abnormal nuclear morphology during interphase. In addition, membrane-associated progerin forms visible cytoplasmic aggregates in mitosis. To examine the potential effects of cytoplasmic progerin, nuclear localization signal (NLS) deleted progerin and lamin A (PGΔNLS and LAΔNLS, respectively) have been constructed. We find that both ΔNLS mutants are farnesylated in the cytosol and associate with a sub-domain of the ER via their farnesyl tails. While the farnesylation on LAΔNLS can be gradually removed, which leads to its subsequent release from the ER into the cytoplasm, PGΔNLS remains permanently farnesylated and membrane-bounded. Moreover, both ΔNLS mutants dominantly affect emerin's nuclear localization. These results reveal new insights into lamin A biogenesis and lamin A-emerin interaction.
| S-EPMC4028357 | biostudies-literature
Project description:Hutchinson-Gilford progeria syndrome (HGPS) is a rare autosomal dominant genetic disease that is caused by a silent mutation of the LMNA gene encoding lamins A and C (lamin A/C). The G608G mutation generates a more accessible splicing donor site than does WT and produces an alternatively spliced product of LMNA called progerin, which is also expressed in normal aged cells. In this study, we determined that progerin binds directly to lamin A/C and induces profound nuclear aberrations. Given this observation, we performed a random screening of a chemical library and identified 3 compounds (JH1, JH4, and JH13) that efficiently block progerin-lamin A/C binding. These 3 chemicals, particularly JH4, alleviated nuclear deformation and reversed senescence markers characteristic of HGPS cells, including growth arrest and senescence-associated β-gal (SA-β-gal) activity. We then used microarray-based analysis to demonstrate that JH4 is able to rescue defects of cell-cycle progression in both HGPS and aged cells. Furthermore, administration of JH4 to LmnaG609G/G609G-mutant mice, which phenocopy human HGPS, resulted in a marked improvement of several progeria phenotypes and an extended lifespan. Together, these findings indicate that specific inhibitors with the ability to block pathological progerin-lamin A/C binding may represent a promising strategy for improving lifespan and health in both HGPS and normal aging.
| S-EPMC5096810 | biostudies-literature
Project description:Given the clinical effect of laminopathies, understanding lamin mechanical properties will benefit the treatment of heart failure. Here we report a mechano-dynamic study of LMNA mutations in neonatal rat ventricular myocytes (NRVM) using single cell spectroscopy with Atomic Force Microscopy (AFM) and measured changes in beating force, frequency and contractile amplitude of selected mutant-expressing cells within cell clusters. Furthermore, since beat-to-beat variations can provide clues on the origin of arrhythmias, we analyzed the beating rate variability using a time-domain method which provides a Poincaré plot. Data were further correlated to cell phenotypes. Immunofluorescence and calcium imaging analysis showed that mutant lamin changed NRVMs beating force and frequency. Additionally, we noted an altered microtubule network organization with shorter filament length, and defective hemichannel membrane localization (Connexin 43). These data highlight the interconnection between nucleoskeleton, cytoskeleton and sarcolemmal structures, and the transcellular consequences of mutant lamin protein in the pathogenesis of the cardiac laminopathies.
| S-EPMC6992992 | biostudies-literature
Project description:Interphase phosphorylation of lamin-A,C depends dynamically on a cell's microenvironment, including the stiffness of extracellular matrix. However, phosphorylation dynamics is poorly understood for diseased forms such as progerin, a permanently farnesylated mutant of LMNA that accelerates aging of stiff and mechanically stressed tissues. Here, fine-excision alignment mass spectrometry (FEA-MS) is developed to quantify progerin and its phosphorylation levels in patient iPS cells differentiated to mesenchymal stem cells (MSCs). The stoichiometry of total A-type lamins (including progerin) versus B-type lamins measured for Progeria iPS-MSCs prove similar to that of normal MSCs, with total A-type lamins more abundant than B-type lamins. However, progerin behaves more like farnesylated B-type lamins in mechanically-induced segregation from nuclear blebs. Phosphorylation of progerin at multiple sites in iPS-MSCs cultured on rigid plastic is also lower than that of normal lamin-A and C. Reduction of nuclear tension upon i) cell rounding/detachment from plastic, ii) culture on soft gels, and iii) inhibition of actomyosin stress increases phosphorylation and degradation of lamin-C > lamin-A > progerin. Such mechano-sensitivity diminishes, however, with passage as progerin and DNA damage accumulate. Lastly, transcription-regulating retinoids exert equal effects on both diseased and normal A-type lamins, suggesting a differential mechano-responsiveness might best explain the stiff tissue defects in Progeria.
| S-EPMC5973135 | biostudies-literature
Project description:Werner syndrome (WRN) is a rare progressive genetic disorder, caused by functional defects in WRN protein and RecQ4L DNA helicase. Acceleration of the aging process is initiated at puberty and the expected life span is approximately the late 50 s. However, a Wrn-deficient mouse model does not show premature aging phenotypes or a short life span, implying that aging processes differ greatly between humans and mice. Gene expression analysis of WRN cells reveals very similar results to gene expression analysis of Hutchinson Gilford progeria syndrome (HGPS) cells, suggesting that these human progeroid syndromes share a common pathological mechanism. Here we show that WRN cells also express progerin, an abnormal variant of the lamin A protein. In addition, we reveal that duplicated sequences of human WRN (hWRN) from exon 9 to exon 10, which differ from the sequence of mouse WRN (mWRN), are a natural inhibitor of progerin. Overexpression of hWRN reduced progerin expression and aging features in HGPS cells. Furthermore, the elimination of progerin by siRNA or a progerin-inhibitor (SLC-D011 also called progerinin) can ameliorate senescence phenotypes in WRN fibroblasts and cardiomyocytes, derived from WRN-iPSCs. These results suggest that progerin, which easily accumulates under WRN-deficient conditions, can lead to premature aging in WRN and that this effect can be prevented by SLC-D011.
| S-EPMC8079706 | biostudies-literature
Project description:Hutchinson-Gilford progeria syndrome (HGPS) is an extremely rare genetic disorder caused by the mutant protein progerin, which is expressed by the abnormal splicing of the LMNA gene. HGPS affects systemic levels, with the exception of cognition or brain development, in children, showing that cellular aging can occur in the short term. Studying progeria could be useful in unraveling the causes of human aging (as well as fatal age-related disorders). Elucidating the clear cause of HGPS or the development of a therapeutic medicine could improve the quality of life and extend the survival of patients. This review aimed to (i) briefly describe how progerin was discovered as the causative agent of HGPS, (ii) elucidate the puzzling observation of the absence of primary neurological disease in HGPS, (iii) present several studies showing the deleterious effects of progerin and the beneficial effects of its inhibition, and (iv) summarize research to develop a therapy for HGPS and introduce clinical trials for its treatment.
| S-EPMC10527460 | biostudies-literature