RESUMO
Progerin, a mutated lamin A, causes the severe premature-aging syndrome Hutchinson-Gilford progeria (HGPS). Kubben et al. present a driving mechanism for HGPS involving trapping of NRF2 at the nuclear periphery by progerin. This local restriction results in impaired NRF2 signaling and chronic oxidative stress.
Assuntos
Lamina Tipo A/metabolismo , Progéria/metabolismo , Núcleo Celular/metabolismo , Humanos , Proteínas Nucleares/metabolismo , Estresse Oxidativo , Precursores de Proteínas/metabolismoRESUMO
Hutchinson-Gilford progeria syndrome (HGPS) is a rare, invariably fatal premature aging disorder. The disease is caused by constitutive production of progerin, a mutant form of the nuclear architectural protein lamin A, leading, through unknown mechanisms, to diverse morphological, epigenetic, and genomic damage and to mesenchymal stem cell (MSC) attrition in vivo. Using a high-throughput siRNA screen, we identify the NRF2 antioxidant pathway as a driver mechanism in HGPS. Progerin sequesters NRF2 and thereby causes its subnuclear mislocalization, resulting in impaired NRF2 transcriptional activity and consequently increased chronic oxidative stress. Suppressed NRF2 activity or increased oxidative stress is sufficient to recapitulate HGPS aging defects, whereas reactivation of NRF2 activity in HGPS patient cells reverses progerin-associated nuclear aging defects and restores in vivo viability of MSCs in an animal model. These findings identify repression of the NRF2-mediated antioxidative response as a key contributor to the premature aging phenotype.
Assuntos
Senilidade Prematura/metabolismo , Antioxidantes/metabolismo , Fator 2 Relacionado a NF-E2/metabolismo , Progéria/metabolismo , Senilidade Prematura/genética , Linhagem Celular , Sobrevivência Celular , Células-Tronco Mesenquimais/citologia , Células-Tronco Mesenquimais/metabolismo , Fator 2 Relacionado a NF-E2/genética , Progéria/genética , RNA Interferente Pequeno , Fatores de Transcrição/metabolismo , Transcrição GênicaRESUMO
Hepatic glucose release into the circulation is vital for brain function and survival during periods of fasting and is modulated by an array of hormones that precisely regulate plasma glucose levels. We have identified a fasting-induced protein hormone that modulates hepatic glucose release. It is the C-terminal cleavage product of profibrillin, and we name it Asprosin. Asprosin is secreted by white adipose, circulates at nanomolar levels, and is recruited to the liver, where it activates the G protein-cAMP-PKA pathway, resulting in rapid glucose release into the circulation. Humans and mice with insulin resistance show pathologically elevated plasma asprosin, and its loss of function via immunologic or genetic means has a profound glucose- and insulin-lowering effect secondary to reduced hepatic glucose release. Asprosin represents a glucogenic protein hormone, and therapeutically targeting it may be beneficial in type II diabetes and metabolic syndrome.
Assuntos
Jejum/metabolismo , Proteínas dos Microfilamentos/metabolismo , Fragmentos de Peptídeos/metabolismo , Hormônios Peptídicos/metabolismo , Tecido Adiposo Branco/metabolismo , Sequência de Aminoácidos , Animais , Anticorpos/administração & dosagem , Ritmo Circadiano , AMP Cíclico/metabolismo , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Jejum/sangue , Feminino , Retardo do Crescimento Fetal/metabolismo , Fibrilina-1 , Glucose/metabolismo , Humanos , Insulina/metabolismo , Fígado/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Obesos , Proteínas dos Microfilamentos/sangue , Proteínas dos Microfilamentos/química , Proteínas dos Microfilamentos/genética , Dados de Sequência Molecular , Fragmentos de Peptídeos/sangue , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/genética , Hormônios Peptídicos/sangue , Hormônios Peptídicos/química , Hormônios Peptídicos/genética , Progéria/metabolismo , Proteínas Recombinantes/administração & dosagem , Alinhamento de SequênciaRESUMO
Ageing is the predominant risk factor for many common diseases. Human premature ageing diseases are powerful model systems to identify and characterize cellular mechanisms that underpin physiological ageing. Their study also leads to a better understanding of the causes, drivers and potential therapeutic strategies of common diseases associated with ageing, including neurological disorders, diabetes, cardiovascular diseases and cancer. Using the rare premature ageing disorder Hutchinson-Gilford progeria syndrome as a paradigm, we discuss here the shared mechanisms between premature ageing and ageing-associated diseases, including defects in genetic, epigenetic and metabolic pathways; mitochondrial and protein homeostasis; cell cycle; and stem cell-regenerative capacity.
Assuntos
Senilidade Prematura/metabolismo , Senilidade Prematura/patologia , Envelhecimento/metabolismo , Envelhecimento/patologia , Envelhecimento/genética , Senilidade Prematura/genética , Animais , Reparo do DNA , Epigênese Genética , Instabilidade Genômica , Humanos , Progéria/genética , Progéria/metabolismo , Progéria/patologiaRESUMO
Human LMNA gene mutations result in laminopathies that include Emery-Dreifuss muscular dystrophy (AD-EDMD) and Hutchinson-Gilford progeria, the premature aging syndrome (HGPS). The Lmna null (Lmna(-/-)) and progeroid LmnaΔ9 mutant mice are models for AD-EDMD and HGPS, respectively. Both animals develop severe tissue pathologies with abbreviated life spans. Like HGPS cells, Lmna(-/-) and LmnaΔ9 fibroblasts have typically misshapen nuclei. Unexpectedly, Lmna(-/-) or LmnaΔ9 mice that are also deficient for the inner nuclear membrane protein Sun1 show markedly reduced tissue pathologies and enhanced longevity. Concordantly, reduction of SUN1 overaccumulation in LMNA mutant fibroblasts and in cells derived from HGPS patients corrected nuclear defects and cellular senescence. Collectively, these findings implicate Sun1 protein accumulation as a common pathogenic event in Lmna(-/-), LmnaΔ9, and HGPS disorders.
Assuntos
Lamina Tipo A/metabolismo , Proteínas de Membrana/metabolismo , Proteínas Associadas aos Microtúbulos/metabolismo , Distrofia Muscular de Emery-Dreifuss/metabolismo , Distrofia Muscular de Emery-Dreifuss/patologia , Proteínas Nucleares/metabolismo , Progéria/metabolismo , Animais , Linhagem Celular , Senescência Celular , Modelos Animais de Doenças , Fibroblastos/metabolismo , Humanos , Camundongos , Camundongos Knockout , Proteínas Associadas aos Microtúbulos/genética , Progéria/patologiaRESUMO
Progerin, the protein that causes Hutchinson-Gilford progeria syndrome, triggers nuclear membrane (NM) ruptures and blebs, but the mechanisms are unclear. We suspected that the expression of progerin changes the overall structure of the nuclear lamina. High-resolution microscopy of smooth muscle cells (SMCs) revealed that lamin A and lamin B1 form independent meshworks with uniformly spaced openings (~0.085 µm2). The expression of progerin in SMCs resulted in the formation of an irregular meshwork with clusters of large openings (up to 1.4 µm2). The expression of progerin acted in a dominant-negative fashion to disrupt the morphology of the endogenous lamin B1 meshwork, triggering irregularities and large openings that closely resembled the irregularities and openings in the progerin meshwork. These abnormal meshworks were strongly associated with NM ruptures and blebs. Of note, the progerin meshwork was markedly abnormal in nuclear blebs that were deficient in lamin B1 (~50% of all blebs). That observation suggested that higher levels of lamin B1 expression might normalize the progerin meshwork and prevent NM ruptures and blebs. Indeed, increased lamin B1 expression reversed the morphological abnormalities in the progerin meshwork and markedly reduced the frequency of NM ruptures and blebs. Thus, progerin expression disrupts the overall structure of the nuclear lamina, but that effect-along with NM ruptures and blebs-can be abrogated by increased lamin B1 expression.
Assuntos
Lamina Tipo A , Lamina Tipo B , Lâmina Nuclear , Lâmina Nuclear/metabolismo , Lamina Tipo A/metabolismo , Lamina Tipo A/genética , Lamina Tipo B/metabolismo , Lamina Tipo B/genética , Humanos , Progéria/metabolismo , Progéria/genética , Progéria/patologia , Animais , Precursores de Proteínas/metabolismo , Precursores de Proteínas/genética , Miócitos de Músculo Liso/metabolismo , Miócitos de Músculo Liso/patologia , CamundongosRESUMO
Hutchinson-Gilford progeria syndrome (HGPS) is a rare disease caused by the expression of progerin, a mutant protein that accelerates aging and precipitates death. Given that atherosclerosis complications are the main cause of death in progeria, here, we investigated whether progerin-induced atherosclerosis is prevented in HGPSrev-Cdh5-CreERT2 and HGPSrev-SM22α-Cre mice with progerin suppression in endothelial cells (ECs) and vascular smooth muscle cells (VSMCs), respectively. HGPSrev-Cdh5-CreERT2 mice were undistinguishable from HGPSrev mice with ubiquitous progerin expression, in contrast with the ameliorated progeroid phenotype of HGPSrev-SM22α-Cre mice. To study atherosclerosis, we generated atheroprone mouse models by overexpressing a PCSK9 gain-of-function mutant. While HGPSrev-Cdh5-CreERT2 and HGPSrev mice developed a similar level of excessive atherosclerosis, plaque development in HGPSrev-SM22α-Cre mice was reduced to wild-type levels. Our studies demonstrate that progerin suppression in VSMCs, but not in ECs, prevents exacerbated atherosclerosis in progeroid mice.
Assuntos
Aterosclerose , Células Endoteliais , Lamina Tipo A , Músculo Liso Vascular , Progéria , Animais , Camundongos , Aterosclerose/genética , Aterosclerose/metabolismo , Aterosclerose/patologia , Modelos Animais de Doenças , Células Endoteliais/metabolismo , Células Endoteliais/patologia , Lamina Tipo A/metabolismo , Lamina Tipo A/genética , Camundongos Transgênicos , Músculo Liso Vascular/metabolismo , Músculo Liso Vascular/patologia , Miócitos de Músculo Liso/metabolismo , Miócitos de Músculo Liso/patologia , Progéria/metabolismo , Progéria/genética , Progéria/patologia , Pró-Proteína Convertase 9/metabolismo , Pró-Proteína Convertase 9/genéticaRESUMO
Patients with Hutchinson-Gilford progeria syndrome (HGPS) present with a number of premature aging phenotypes, including DNA damage accumulation, and many of them die of cardiovascular complications. Although vascular pathologies have been reported, whether HGPS patients exhibit cardiac dysfunction and its underlying mechanism is unclear, rendering limited options for treating HGPS-related cardiomyopathy. In this study, we reported a cardiac atrophy phenotype in the LmnaG609G/G609G mice (hereafter, HGPS mice). Using a GFP-based reporter system, we demonstrated that the efficiency of nonhomologous end joining (NHEJ) declined by 50% in HGPS cardiomyocytes in vivo, due to the attenuated interaction between γH2AX and Progerin, the causative factor of HGPS. As a result, genomic instability in cardiomyocytes led to an increase of CHK2 protein level, promoting the LKB1-AMPKα interaction and AMPKα phosphorylation, which further led to the activation of FOXO3A-mediated transcription of atrophy-related genes. Moreover, inhibiting AMPK enlarged cardiomyocyte sizes both in vitro and in vivo. Most importantly, our proof-of-concept study indicated that isoproterenol treatment significantly reduced AMPKα and FOXO3A phosphorylation in the heart, attenuated the atrophy phenotype, and extended the mean lifespan of HGPS mice by ~21%, implying that targeting cardiac atrophy may be an approach to HGPS treatment.
Assuntos
Senilidade Prematura , Progéria , Humanos , Camundongos , Animais , Progéria/metabolismo , Coração , Dano ao DNA , Instabilidade Genômica , Proteínas Quinases Ativadas por AMP/genética , Lamina Tipo A/genética , Lamina Tipo A/metabolismoRESUMO
Many recent advances have emerged in the telomere and telomerase fields. This Timeline article highlights the key advances that have expanded our views on the mechanistic underpinnings of telomeres and telomerase and their roles in ageing and disease. Three decades ago, the classic view was that telomeres protected the natural ends of linear chromosomes and that telomerase was a specific telomere-terminal transferase necessary for the replication of chromosome ends in single-celled organisms. While this concept is still correct, many diverse fields associated with telomeres and telomerase have substantially matured. These areas include the discovery of most of the key molecular components of telomerase, implications for limits to cellular replication, identification and characterization of human genetic disorders that result in premature telomere shortening, the concept that inhibiting telomerase might be a successful therapeutic strategy and roles for telomeres in regulating gene expression. We discuss progress in these areas and conclude with challenges and unanswered questions in the field.
Assuntos
Envelhecimento/genética , Genômica/história , Neoplasias/genética , Telomerase/genética , Telômero/química , Anormalidades Múltiplas/genética , Anormalidades Múltiplas/metabolismo , Anormalidades Múltiplas/patologia , Envelhecimento/metabolismo , Animais , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , DNA/química , DNA/genética , DNA/metabolismo , Regulação da Expressão Gênica , Genômica/métodos , História do Século XX , História do Século XXI , Humanos , Chaperonas Moleculares , Neoplasias/metabolismo , Neoplasias/patologia , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Progéria/genética , Progéria/metabolismo , Progéria/patologia , Ribonucleoproteínas Nucleares Pequenas/genética , Ribonucleoproteínas Nucleares Pequenas/metabolismo , Ribonucleoproteínas Nucleolares Pequenas/genética , Ribonucleoproteínas Nucleolares Pequenas/metabolismo , Complexo Shelterina , Telomerase/metabolismo , Telômero/metabolismo , Homeostase do Telômero , Proteínas de Ligação a Telômeros/genética , Proteínas de Ligação a Telômeros/metabolismoRESUMO
BACKGROUND: Hutchinson-Gilford progeria syndrome (HGPS) is an ultrarare, fatal, premature aging disease caused by a toxic protein called progerin. Circulating progerin has not been previously detected, precluding research using readily available biological samples. This study aimed to develop a plasma progerin assay to evaluate progerin's quantity, response to progerin-targeted therapy, and relationship to patient survival. METHODS: Biological samples were collected by The Progeria Research Foundation Cell and Tissue Bank from a non-HGPS cohort cross-sectionally and a HGPS cohort longitudinally. HGPS donations occurred at baseline and intermittently while treated with farnesylation inhibitors lonafarnib±pravastatin and zoledronate, within 3 sequential open-label clinical trials at Boston Children's Hospital totaling >10 years of treatment. An ultrasensitive single-molecule counting progerin immunoassay was developed with prespecified performance parameters. Intra- and interpatient group statistics were descriptive. The relationship between progerin and survival was assessed by using joint modeling with time-dependent slopes parameterization. RESULTS: The assay's dynamic detection range was 59 to 30 000 pg/mL (R2=0.9987). There was no lamin A cross-reactivity. Mean plasma progerin in non-HGPS participants (n=69; 39 male, 30 female; age, 0.2-71.3 years) was 351±251 pg/mL, and in drug-naive participants with HGPS (n=74; 37 female, 37 male; age, 2.1-17.5 years) was 33 261±12 346 pg/mL, reflecting a 95-fold increase in affected children (P<0.0001). Progerin levels did not differ by sex (P=0.99). Lonafarnib treatment resulted in an average per-visit progerin decrease from baseline of between 35% to 62% (all P<0.005); effects were not augmented by adding pravastatin and zoledronate. Progerin levels fell within 4 months of therapy and remained lower for up to 10 years. The magnitude of progerin decrease positively associated with patient survival (P<0.0001; ie, 15 000 pg/mL decrease yields a 63.9% decreased risk of death). For any given decrease in progerin, life expectancy incrementally increased with longer treatment duration. CONCLUSIONS: A sensitive, quantitative immunoassay for progerin was developed and used to demonstrate high progerin levels in HGPS plasma that decreased with lonafarnib therapy. The extent of improved survival was associated with both the magnitude of progerin decrease and duration at lower levels. Thus, plasma progerin is a biomarker for HGPS whose reduction enables short- and long-term assessment of progerin-targeted treatment efficacy. REGISTRATION: URL: https://www. CLINICALTRIALS: gov. Unique identifiers: NCT00879034 and NCT00916747.
Assuntos
Progéria , Criança , Humanos , Masculino , Feminino , Lactente , Pré-Escolar , Adolescente , Adulto Jovem , Adulto , Pessoa de Meia-Idade , Idoso , Progéria/diagnóstico , Progéria/tratamento farmacológico , Progéria/metabolismo , Ácido Zoledrônico/uso terapêutico , Pravastatina/uso terapêutico , Piperidinas/uso terapêutico , Lamina Tipo A/metabolismoRESUMO
The LMNA gene encodes for the nuclear envelope proteins lamin A and C (lamin A/C). A novel R133L heterozygous mutation in the LMNA gene causes atypical progeria syndrome (APS). However, the underlying mechanism remains unclear. Here, we used transgenic mice (LmnaR133L/+ mice) that expressed a heterozygous LMNA R133L mutation and 3T3-L1 cell lines with stable overexpression of LMNA R133L (by lentiviral transduction) as in vivo and in vitro models to investigate the mechanisms of LMNA R133L mutations that mediate the APS phenotype. We found that a heterozygous R133L mutation in LMNA induced most of the metabolic disturbances seen in patients with this mutation, including ectopic lipid accumulation, limited subcutaneous adipose tissue (SAT) expansion, and insulin resistance. Mitochondrial dysfunction and senescence promote ectopic lipid accumulation and insulin resistance. In addition, the FLAG-mediated pull-down capture followed by mass spectrometry assay showed that p160 Myb-binding protein (P160 MBP; Mybbp1 a $$ a $$ ), the critical transcriptional repressor of PGC-1α, was bound to lamin A/C. Increased Mybbp1 a $$ a $$ levels in tissues and greater Mybbp1 a $$ a $$ -lamin A/C binding in nuclear inhibit PGC-1α activity and promotes mitochondrial dysfunction. Our findings confirm that the novel R133L heterozygous mutation in the LMNA gene caused APS are associated with marked mitochondrial respiratory chain impairment, which were induced by decreased PGC-1α levels correlating with increased Mybbp1a levels in nuclear, and a senescence phenotype of the subcutaneous fat.
Assuntos
Envelhecimento , Lamina Tipo A , Progéria , Animais , Camundongos , Tecido Adiposo/metabolismo , Envelhecimento/genética , Resistência à Insulina , Lamina Tipo A/genética , Lamina Tipo A/metabolismo , Lipídeos , Mitocôndrias/genética , Mitocôndrias/metabolismo , Mutação , Progéria/genética , Progéria/metabolismoRESUMO
As the repository of genetic information, the cell nucleus must protect DNA integrity from mechanical stresses. The nuclear lamina, which resides within the nuclear envelope (NE), is made up of lamins, intermediate filaments bound to DNA. The nuclear lamina provides the nucleus with the ability to deal with inward as well as outward mechanical stimuli. Chromatin, in turn, through its degrees of compaction, shares this role with the nuclear lamina, thus, ensuring the plasticity of the nucleus. Perturbation of chromatin condensation or the nuclear lamina has been linked to a plethora of biological conditions, that range from cancer and genetic diseases (laminopathies) to aging, both natural and accelerated, such as the case of Hutchinson-Gilford Progeria Syndrome (HGPS). From the experimental results accumulated so far on the topic, a direct link between variations of the epigenetic pattern and nuclear lamina structure would be suggested, however, it has never been clarified thoroughly. This relationship, instead, has a downstream important implication on nucleus shape, genome preservation, force sensing, and, ultimately, aging-related disease onset. With this review, we aim to collect recent studies on the importance of both nuclear lamina components and chromatin status in nuclear mechanics. We also aim to bring to light evidence of the link between DNA methylation and nuclear lamina in natural and accelerated aging.
Assuntos
Cromatina , Progéria , Humanos , Cromatina/metabolismo , Lâmina Nuclear , Núcleo Celular/metabolismo , Progéria/genética , Progéria/metabolismo , Epigênese Genética , Lamina Tipo A/genética , Lamina Tipo A/metabolismoRESUMO
Hutchinson-Gilford progeria syndrome (HGPS) or progeria is a rare genetic disease that causes premature aging, leading to a drastic reduction in the life expectancy of patients. Progeria is mainly caused by the intracellular accumulation of a defective protein called progerin, generated from a mutation in the LMNA gene. Currently, there is only one approved drug for the treatment of progeria, which has limited efficacy. It is believed that progerin levels are the most important biomarker related to the severity of the disease. However, there is a lack of effective tools to directly visualize progerin in the native cellular models, since the commercially available antibodies are not well suited for the direct visualization of progerin in cells from the mouse model of the disease. In this context, an alternative option for the visualization of a protein relies on the use of fluorescent chemical probes, molecules with affinity and specificity towards a protein. In this work we report the synthesis and characterization of a new fluorescent probe (UCM-23079) that allows for the direct visualization of progerin in cells from the most widely used progeroid mouse model. Thus, UCM-23079 is a new tool compound that could help prioritize potential preclinical therapies towards the final goal of finding a definitive cure for progeria.
Assuntos
Progéria , Camundongos , Animais , Humanos , Progéria/tratamento farmacológico , Progéria/genética , Progéria/metabolismo , Corantes Fluorescentes/uso terapêutico , MutaçãoRESUMO
DNA double-strand breaks (DSBs) are rare, but highly toxic, lesions requiring orchestrated and conserved machinery to prevent adverse consequences, such as cell death and cancer-causing genome structural mutations. DSBs trigger the DNA damage response (DDR) that directs a cell to repair the break, undergo apoptosis, or become senescent. There is increasing evidence that the various endpoints of DSB processing by different cells and tissues are part of the aging phenotype, with each stage of the DDR associated with specific aging pathologies. In this Perspective, we discuss the possibility that DSBs are major drivers of intrinsic aging, highlighting the dynamics of spontaneous DSBs in relation to aging, the distinct age-related pathologies induced by DSBs, and the segmental progeroid phenotypes in humans and mice with genetic defects in DSB repair. A model is presented as to how DSBs could drive some of the basic mechanisms underlying age-related functional decline and death.
Assuntos
Envelhecimento/genética , Quebras de DNA de Cadeia Dupla , Reparo do DNA , DNA/genética , Regulação da Expressão Gênica , Progéria/genética , Hidrolases Anidrido Ácido , Envelhecimento/metabolismo , Envelhecimento/patologia , Animais , Proteína BRCA1/genética , Proteína BRCA1/metabolismo , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Senescência Celular , DNA/metabolismo , Enzimas Reparadoras do DNA/genética , Enzimas Reparadoras do DNA/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Endonucleases/genética , Endonucleases/metabolismo , Humanos , Autoantígeno Ku/genética , Autoantígeno Ku/metabolismo , Proteína Homóloga a MRE11 , Camundongos , Modelos Genéticos , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Progéria/metabolismo , Progéria/patologia , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Transdução de SinaisRESUMO
Barrier-to-autointegration factor (BAF/BANF) is a nuclear lamina protein essential for nuclear integrity, chromatin structure, and genome stability. Whereas complete loss of BAF causes lethality in multiple organisms, the A12T missense mutation of the BANF1 gene in humans causes a premature aging syndrome, called Néstor-Guillermo Progeria Syndrome (NGPS). Here, we report the first in vivo animal investigation of progeroid BAF, using CRISPR editing to introduce the NGPS mutation into the endogenous Drosophila baf gene. Progeroid BAF adults are born at expected frequencies, demonstrating that this BAF variant retains some function. However, tissue homeostasis is affected, supported by studies of the ovary, a tissue that depends upon BAF for stem cell survival and continuous oocyte production. We find that progeroid BAF causes defects in germline stem cell mitosis that delay anaphase progression and compromise chromosome segregation. We link these defects to decreased recruitment of centromeric proteins of the kinetochore, indicating dysfunction of cenBAF, a localized pool of dephosphorylated BAF produced by Protein Phosphatase PP4. We show that DNA damage increases in progenitor germ cells, which causes germ cell death due to activation of the DNA damage transducer kinase Chk2. Mitotic defects appear widespread, as aberrant chromosome segregation and increased apoptosis occur in another tissue. Together, these data highlight the importance of BAF in establishing centromeric structures critical for mitosis. Further, these studies link defects in cenBAF function to activation of a checkpoint that depletes progenitor reserves critical for tissue homeostasis, aligning with phenotypes of NGPS patients.
Assuntos
Drosophila , Progéria , Animais , Feminino , Humanos , Drosophila/metabolismo , Progéria/genética , Progéria/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas Nucleares/metabolismo , Centrômero/metabolismo , Homeostase/genéticaRESUMO
Mutations in the lamin A/C gene (LMNA) cause laminopathies such as the premature aging Hutchinson Gilford progeria syndrome (HGPS) and altered lamin A/C levels are found in diverse malignancies. The underlying lamin-associated mechanisms remain poorly understood. Here we report that lamin A/C-null mouse embryo fibroblasts (Lmna-/- MEFs) and human progerin-expressing HGPS fibroblasts both display reduced NAD+ levels, unstable mitochondrial DNA and attenuated bioenergetics. This mitochondrial dysfunction is associated with reduced chromatin recruitment (Lmna-/- MEFs) or low levels (HGPS) of PGC1α, the key transcription factor for mitochondrial homeostasis. Lmna-/- MEFs showed reduced expression of the NAD+-biosynthesis enzyme NAMPT and attenuated activity of the NAD+-dependent deacetylase SIRT1. We find high PARylation in lamin A/C-aberrant cells, further decreasing the NAD+ pool and consistent with impaired DNA base excision repair in both cell models, a condition that fuels DNA damage-induced PARylation under oxidative stress. Further, ATAC-sequencing revealed a substantially altered chromatin landscape in Lmna-/- MEFs, including aberrantly reduced accessibility at the Nampt gene promoter. Thus, we identified a new role of lamin A/C as a key modulator of mitochondrial function through impairments of PGC1α and the NAMPT-NAD+ pathway, with broader implications for the aging process.
Assuntos
Lamina Tipo A/metabolismo , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/metabolismo , Progéria , Animais , Cromatina/metabolismo , DNA Mitocondrial/metabolismo , Fibroblastos/metabolismo , Humanos , Lamina Tipo A/genética , Camundongos , Mitocôndrias/metabolismo , NAD/metabolismo , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/genética , Progéria/metabolismo , Sirtuína 1/genéticaRESUMO
Nestor-Guillermo progeria syndrome (NGPS) is caused by a homozygous alanine-to-threonine mutation at position 12 (A12T) in barrier-to-autointegration factor (BAF). It is characterized by accelerated aging with severe skeletal abnormalities. BAF is an essential protein binding to DNA and nuclear envelope (NE) proteins, involved in NE rupture repair. Here, we assessed the impact of BAF A12T on NE integrity using NGPS-derived patient fibroblasts. We observed a strong defect in lamin A/C accumulation to NE ruptures in NGPS cells, restored upon homozygous reversion of the pathogenic BAF A12T mutation with CRISPR/Cas9. By combining in vitro and cellular assays, we demonstrated that while the A12T mutation does not affect BAF 3D structure and phosphorylation by VRK1, it specifically decreases the interaction between BAF and lamin A/C. Finally, we revealed that the disrupted interaction does not prevent repair of NE ruptures but instead generates weak points in the NE that lead to a higher frequency of NE re-rupturing in NGPS cells. We propose that this NE fragility could directly contribute to the premature aging phenotype in patients.
Assuntos
Senilidade Prematura , Progéria , Humanos , Membrana Nuclear/genética , Membrana Nuclear/metabolismo , Lamina Tipo A/genética , Lamina Tipo A/metabolismo , Progéria/metabolismo , Senilidade Prematura/metabolismo , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Proteínas de Ligação a DNA/genética , Mutação , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Proteínas Serina-Treonina Quinases , Peptídeos e Proteínas de Sinalização Intracelular/metabolismoRESUMO
Recent research into laminopathic lipodystrophies-rare genetic disorders caused by mutations in the LMNA gene-has greatly expanded our knowledge of their complex pathology and metabolic implications. These disorders, including Hutchinson-Gilford progeria syndrome (HGPS), Mandibuloacral Dysplasia (MAD), and Familial Partial Lipodystrophy (FPLD), serve as crucial models for studying accelerated aging and metabolic dysfunction, enhancing our understanding of the cellular and molecular mechanisms involved. Research on laminopathies has highlighted how LMNA mutations disrupt adipose tissue function and metabolic regulation, leading to altered fat distribution and metabolic pathway dysfunctions. Such insights improve our understanding of the pathophysiological interactions between genetic anomalies and metabolic processes. This review merges current knowledge on the phenotypic classifications of these diseases and their associated metabolic complications, such as insulin resistance, hypertriglyceridemia, hepatic steatosis, and metabolic syndrome, all of which elevate the risk of cardiovascular disease, stroke, and diabetes. Additionally, a range of published therapeutic strategies, including gene editing, antisense oligonucleotides, and novel pharmacological interventions aimed at addressing defective adipocyte differentiation and lipid metabolism, will be explored. These therapies target the core dysfunctional lamin A protein, aiming to mitigate symptoms and provide a foundation for addressing similar metabolic and genetic disorders.
Assuntos
Lamina Tipo A , Lipodistrofia , Humanos , Lamina Tipo A/genética , Lamina Tipo A/metabolismo , Lipodistrofia/genética , Lipodistrofia/metabolismo , Lipodistrofia/terapia , Animais , Laminopatias/genética , Laminopatias/metabolismo , Progéria/genética , Progéria/metabolismo , Progéria/patologia , Mutação , Lipodistrofia Parcial Familiar/genética , Lipodistrofia Parcial Familiar/metabolismo , Lipodistrofia Parcial Familiar/terapia , Metabolismo dos Lipídeos/genética , Tecido Adiposo/metabolismo , Tecido Adiposo/patologia , Resistência à Insulina/genética , Edição de GenesRESUMO
Cardiovascular diseases, atherosclerosis, and strokes are the most common causes of death in patients with Hutchinson-Gilford progeria syndrome (HGPS). The LMNA variant c.1824C > T accounts for ~ 90% of HGPS cases. The detailed molecular mechanisms of Lamin A in the heart remain elusive due to the lack of appropriate in vitro models. We hypothesize that HGPS patient's induced pluripotent stem cell (iPSC)-derived cardiomyocytes (iCMCs) will provide a model platform to study the cardio-pathologic mechanisms associated with HGPS. To elucidate the effects of progerin in cardiomyocytes, we first obtained skin fibroblasts (SFs) from a de-identified HGPS patient (hPGP1, proband) and both parents from the Progeria Research Foundation. Through Sanger sequencing and restriction fragment length polymorphism, with the enzyme EciI, targeting Lamin A, we characterized hPGP1-SFs as heterozygous mutants for the LMNA variant c.1824 C > T. Additionally, we performed LMNA exon 11 bisulfite sequencing to analyze the methylation status of the progeria cells. Furthermore, we reprogrammed the three SFs into iPSCs and differentiated them into iCMCs, which gained a beating on day 7. Through particle image velocimetry analysis, we found that hPGP1-iCMCs had an irregular contractile function and decreased cardiac-specific gene and protein expressions by qRT-PCR and Western blot. Our progeria-patient-derived iCMCs were found to be functionally and structurally defective when compared to normal iCMCs. This in vitro model will help in elucidating the role of Lamin A in cardiac diseases and the cardio-pathologic mechanisms associated with progeria. It provides a new platform for researchers to study novel treatment approaches for progeria-associated cardiac diseases.
Assuntos
Cardiopatias , Progéria , Humanos , Progéria/genética , Progéria/metabolismo , Progéria/patologia , Lamina Tipo A/genética , Lamina Tipo A/metabolismo , Miócitos Cardíacos/metabolismo , Diferenciação CelularRESUMO
Hutchinson-Gilford progeria syndrome (HGPS) is a rare premature aging disease caused by a single-point mutation in the lamin A gene, resulting in a truncated and farnesylated form of lamin A. This mutant lamin A protein, known as progerin, accumulates at the periphery of the nuclear lamina, resulting in both an abnormal nuclear morphology and nuclear stiffening. Patients with HGPS experience rapid onset of atherosclerosis, with death from heart attack or stroke as teenagers. Progerin expression has been shown to cause dysfunction in both vascular smooth muscle cells and endothelial cells (ECs). In this study, we examined how progerin-expressing endothelial cells adapt to fluid shear stress, the principal mechanical force from blood flow. We compared the response to shear stress for progerin-expressing, wild-type lamin A overexpressing, and control endothelial cells to physiological levels of fluid shear stress. Additionally, we also knocked down ZMPSTE24 in endothelial cells, which results in increased farnesylation of lamin A and similar phenotypes to HGPS. Our results showed that endothelial cells either overexpressing progerin or with ZMPSTE24 knockdown were unable to adapt to shear stress, experiencing significant cell loss at a longer duration of exposure to shear stress (3 days). Endothelial cells overexpressing wild-type lamin A also exhibited similar impairments in adaptation to shear stress, including similar levels of cell loss. Quantification of nuclear morphology showed that progerin-expressing endothelial cells had similar nuclear abnormalities in both static and shear conditions. Treatment of progerin-expressing cells and ZMPSTE24 KD cells with lonafarnib and methystat, drugs previously shown to improve HGPS nuclear morphology, resulted in improvements in adaptation to shear stress. Additionally, the prealignment of cells to shear stress before progerin-expression prevented cell loss. Our results demonstrate that changes in nuclear lamins can affect the ability of endothelial cells to properly adapt to shear stress.