RESUMO

Deciphering the dynamic mechanism of ferroptosis can provide insights into pathogenesis, which is valuable for disease diagnosis and treatment. However, due to the lack of suitable time-resolved mechanosensitive tools, researchers have been unable to determine the membrane tension and morphology of the plasma membrane and the nuclear envelope during ferroptosis. With this research, we propose a rational strategy to develop robust mechanosensitive fluorescence lifetime probes which can facilitate simultaneous fluorescence lifetime imaging of the plasma membrane and nuclear envelope. Fluorescence lifetime imaging microscopy using the unique mechanosensitive probes reveal a dynamic mechanism for ferroptosis: The membrane tension of both the plasma membrane and the nuclear envelope decreases during ferroptosis, and the nuclear envelope exhibits budding during the advanced stage of ferroptosis. Significantly, the membrane tension of the plasma membrane is always larger than that of the nuclear envelope, and the membrane tension of the nuclear envelope is slightly larger than that of the nuclear membrane bubble. Meanwhile, the membrane lesions are repaired in the low-tension regions through exocytosis.

Assuntos

Membrana Celular , Ferroptose , Corantes Fluorescentes , Microscopia de Fluorescência , Membrana Nuclear , Ferroptose/fisiologia , Humanos , Corantes Fluorescentes/química , Membrana Celular/metabolismo , Membrana Nuclear/metabolismo , Microscopia de Fluorescência/métodos , Exocitose/fisiologia , Células HeLa

RESUMO

Progerin causes Hutchinson-Gilford progeria syndrome (HGPS), but how progerin accelerates aging is still an interesting question. Here, we provide evidence linking nuclear envelope (NE) budding and accelerated aging. Mechanistically, progerin disrupts nuclear lamina to induce NE budding in concert with lamin A/C, resulting in transport of chromatin into the cytoplasm where it is removed via autophagy, whereas emerin antagonizes this process. Primary cells from both HGPS patients and mouse models express progerin and display NE budding and chromatin loss, and ectopically expressing progerin in cells can mimic this process. More excitingly, we screen a NE budding inhibitor chaetocin by high-throughput screening, which can dramatically sequester progerin from the NE and prevent this NE budding through sustaining ERK1/2 activation. Chaetocin alleviates NE budding-induced chromatin loss and ameliorates HGPS defects in cells and mice and significantly extends lifespan of HGPS mice. Collectively, we propose that progerin-induced NE budding participates in the induction of progeria, highlight the roles of chaetocin and sustained ERK1/2 activation in anti-aging, and provide a distinct avenue for treating HGPS.

Assuntos

Lamina Tipo A , Membrana Nuclear , Proteínas Nucleares , Progéria , Progéria/metabolismo , Progéria/tratamento farmacológico , Progéria/patologia , Progéria/genética , Animais , Lamina Tipo A/metabolismo , Lamina Tipo A/genética , Camundongos , Humanos , Membrana Nuclear/metabolismo , Proteínas Nucleares/metabolismo , Proteínas Nucleares/genética , Envelhecimento/metabolismo , Envelhecimento/efeitos dos fármacos , Cromatina/metabolismo , Proteínas de Membrana/metabolismo , Proteínas de Membrana/genética , Modelos Animais de Doenças , Autofagia/efeitos dos fármacos

RESUMO

The inducers of neutrophil extracellular trap (NET) formation are heterogeneous and consequently, there is no specific pathway or signature molecule indispensable for NET formation. But certain events such as histone modification, chromatin decondensation, nuclear envelope breakdown, and NET release are ubiquitous. During NET formation, neutrophils drastically rearrange their cytoplasmic, granular and nuclear content. Yet, the exact mechanism for decoding each step during NET formation still remains elusive. Here, we investigated the mechanism of nuclear envelope breakdown during NET formation. Immunofluorescence microscopic evaluation revealed a gradual disintegration of outer nuclear membrane protein nesprin-1 and alterations in nuclear morphology during NET formation. MALDI-TOF analysis of NETs that had been generated by various inducers detected the accumulation of nesprin-1 fragments. This suggests that nesprin-1 degradation occurs before NET release. In the presence of a calpain-1, inhibitor nesprin-1 degradation was decreased in calcium driven NET formation. Microscopic evaluation confirmed that the disintegration of the lamin B receptor (LBR) and the collapse of the actin cytoskeleton occurs in early and later phases of NET release, respectively. We conclude that the calpain-1 degrades nesprin-1, orchestrates the weakening of the nuclear membrane, contributes to LBR disintegration, and promoting DNA release and finally, NETs formation.

Assuntos

Calpaína , Armadilhas Extracelulares , Receptor de Lamina B , Neutrófilos , Membrana Nuclear , Membrana Nuclear/metabolismo , Calpaína/metabolismo , Humanos , Armadilhas Extracelulares/metabolismo , Neutrófilos/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Proteínas Nucleares/metabolismo , Receptores Citoplasmáticos e Nucleares/metabolismo , Cálcio/metabolismo , Proteínas do Citoesqueleto

RESUMO

Alterations in nuclear structure and function are hallmarks of cancer cells. Little is known about these changes in Cancer-Associated Fibroblasts (CAFs), crucial components of the tumor microenvironment. Loss of the androgen receptor (AR) in human dermal fibroblasts (HDFs), which triggers early steps of CAF activation, leads to nuclear membrane changes and micronuclei formation, independent of cellular senescence. Similar changes occur in established CAFs and are reversed by restoring AR activity. AR associates with nuclear lamin A/C, and its loss causes lamin A/C nucleoplasmic redistribution. AR serves as a bridge between lamin A/C and the protein phosphatase PPP1. Loss of AR decreases lamin-PPP1 association and increases lamin A/C phosphorylation at Ser 301, a characteristic of CAFs. Phosphorylated lamin A/C at Ser 301 binds to the regulatory region of CAF effector genes of the myofibroblast subtype. Expression of a lamin A/C Ser301 phosphomimetic mutant alone can transform normal fibroblasts into tumor-promoting CAFs.

Assuntos

Fibroblastos Associados a Câncer , Núcleo Celular , Lamina Tipo A , Receptores Androgênicos , Humanos , Receptores Androgênicos/metabolismo , Receptores Androgênicos/genética , Lamina Tipo A/metabolismo , Lamina Tipo A/genética , Fosforilação , Fibroblastos Associados a Câncer/metabolismo , Fibroblastos Associados a Câncer/patologia , Núcleo Celular/metabolismo , Proteína Fosfatase 1/metabolismo , Proteína Fosfatase 1/genética , Fibroblastos/metabolismo , Membrana Nuclear/metabolismo , Masculino , Microambiente Tumoral

RESUMO

BACKGROUND: Periodontal ligament stem cells (PDLSCs) are important seed cells in tissue engineering and clinical applications. They are the priority receptor cells for sensing various mechanical stresses. Yes-associated protein (YAP) is a recognized mechanically sensitive transcription factor. However, the role of YAP in regulating the fate of PDLSCs under tension stress (TS) and its underlying mechanism is still unclear. METHODS: The effects of TS on the morphology and fate of PDLSCs were investigated using fluorescence staining, transmission electron microscopy, flow cytometry and quantitative real-time polymerase chain reaction (qRT-PCR). Then qRT-PCR, western blotting, immunofluorescence staining and gene knockdown experiments were performed to investigate the expression and distribution of YAP and its correlation with PDLSCs proliferation. The effects of cytoskeleton dynamics on YAP nuclear translocation were subsequently explored by adding cytoskeleton inhibitors. The effect of cytoskeleton dynamics on the expression of the LINC complex was proved through qRT-PCR and western blotting. After destroying the LINC complex by adenovirus, the effects of the LINC complex on YAP nuclear translocation and PDLSCs proliferation were investigated. Mitochondria-related detections were then performed to explore the role of mitochondria in YAP nuclear translocation. Finally, the in vitro results were verified by constructing orthodontic tooth movement models in Sprague-Dawley rats. RESULTS: TS enhanced the polymerization and stretching of F-actin, which upregulated the expression of the LINC complex. This further strengthened the pull on the nuclear envelope, enlarged the nuclear pore, and facilitated YAP's nuclear entry, thus enhancing the expression of proliferation-related genes. In this process, mitochondria were transported to the periphery of the nucleus along the reconstructed microtubules. They generated ATP to aid YAP's nuclear translocation and drove F-actin polymerization to a certain degree. When the LINC complex was destroyed, the nuclear translocation of YAP was inhibited, which limited PDLSCs proliferation, impeded periodontal tissue remodeling, and hindered tooth movement. CONCLUSIONS: Our study confirmed that appropriate TS could promote PDLSCs proliferation and periodontal tissue remodeling through the mechanically driven F-actin/LINC complex/YAP axis, which could provide theoretical guidance for seed cell expansion and for promoting healthy and effective tooth movement in clinical practice.

Assuntos

Citoesqueleto , Membrana Nuclear , Ligamento Periodontal , Células-Tronco , Animais , Humanos , Masculino , Ratos , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/genética , Proliferação de Células , Células Cultivadas , Citoesqueleto/metabolismo , Membrana Nuclear/metabolismo , Ligamento Periodontal/metabolismo , Ligamento Periodontal/citologia , Células-Tronco/metabolismo , Células-Tronco/citologia , Estresse Mecânico , Fatores de Transcrição/metabolismo , Fatores de Transcrição/genética , Proteínas de Sinalização YAP/metabolismo

RESUMO

Micronuclei (MN) can form through many mechanisms, including the breakage of aberrant cytokinetic chromatin bridges. The frequent observation of MN in tumors suggests that they might not merely be passive elements but could instead play active roles in tumor progression. Here, we propose a mechanism through which the presence of micronuclei could induce specific phenotypic and functional changes in cells and increase the invasive potential of cancer cells. Through the integration of diverse in vitro imaging and molecular techniques supported by clinical samples from patients with prostate cancer (PCa) defined as high-risk by the D'Amico classification, we demonstrate that the resolution of chromosome bridges can result in the accumulation of Emerin and the formation of Emerin-rich MN. These structures are negative for Lamin A/C and positive for the Lamin-B receptor and Sec61ß. MN can act as a protein sinks and result in the pauperization of Emerin from the nuclear envelope. The Emerin mislocalization phenotype is associated with a molecular signature that is correlated with a poor prognosis in PCa patients and is enriched in metastatic samples. Emerin mislocalization corresponds with increases in the migratory and invasive potential of tumor cells, especially in a collagen-rich microenvironment. Our study demonstrates that the mislocalization of Emerin to MN results in increased cell invasiveness, thereby worsening patient prognosis.

Assuntos

Cromatina , Colágeno , Proteínas de Membrana , Invasividade Neoplásica , Proteínas Nucleares , Neoplasias da Próstata , Microambiente Tumoral , Humanos , Masculino , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Neoplasias da Próstata/genética , Cromatina/metabolismo , Proteínas de Membrana/metabolismo , Proteínas de Membrana/genética , Proteínas Nucleares/metabolismo , Proteínas Nucleares/genética , Linhagem Celular Tumoral , Colágeno/metabolismo , Membrana Nuclear/metabolismo , Micronúcleos com Defeito Cromossômico , Movimento Celular

RESUMO

G protein-coupled receptors (GPCRs) have historically been associated with signalling events driven from the plasma membrane. More recently, signalling from endosomes has been recognized as a feature of internalizing receptors. However, there was little consideration given to the notion that GPCRs can be targeted to distinct subcellular locations that did not involve an initial trafficking to the cell surface. Here, we focus on the evidence for and the potential impact of GPCR signalling specifically initiated from the nuclear membrane. We also discuss the possibilities for selectively targeting this and other internal pools of receptors as novel venues for drug discovery.

Assuntos

Núcleo Celular , Receptores Acoplados a Proteínas G , Transdução de Sinais , Receptores Acoplados a Proteínas G/metabolismo , Humanos , Animais , Núcleo Celular/metabolismo , Membrana Nuclear/metabolismo , Endossomos/metabolismo , Transporte Proteico

RESUMO

In animals, mitosis involves the breakdown of the nuclear envelope and the sorting of individualized, condensed chromosomes. During mitotic exit, emerging nuclei reassemble a nuclear envelope around a single mass of interconnecting chromosomes. The molecular mechanisms of nuclear reassembly are incompletely understood. Moreover, the cellular and physiological consequences of defects in this process are largely unexplored. Here, we have characterized a mechanism essential for nuclear reassembly in Drosophila. We show that Ankle2 promotes the PP2A-dependent recruitment of BAF and Lamin at reassembling nuclei, and that failures in this mechanism result in severe nuclear defects after mitosis. We then took advantage of perturbations in this mechanism to investigate the physiological responses to nuclear reassembly defects during tissue development in vivo. Partial depletion of Ankle2, BAF, or Lamin in imaginal wing discs results in wing development defects accompanied by apoptosis. We found that blocking apoptosis strongly enhances developmental defects. Blocking p53 does not prevent apoptosis but enhances defects due to the loss of a cell cycle checkpoint. Our results suggest that apoptotic and p53-dependent responses play a crucial role in safeguarding tissue development in response to sporadic nuclear reassembly defects.

Assuntos

Apoptose , Núcleo Celular , Proteínas de Drosophila , Drosophila melanogaster , Mitose , Proteína Supressora de Tumor p53 , Asas de Animais , Animais , Proteínas de Drosophila/metabolismo , Proteínas de Drosophila/genética , Proteína Supressora de Tumor p53/metabolismo , Proteína Supressora de Tumor p53/genética , Apoptose/genética , Núcleo Celular/metabolismo , Drosophila melanogaster/metabolismo , Drosophila melanogaster/genética , Asas de Animais/metabolismo , Asas de Animais/crescimento & desenvolvimento , Proteínas de Ligação a DNA/metabolismo , Proteínas de Ligação a DNA/genética , Membrana Nuclear/metabolismo , Laminas/metabolismo , Laminas/genética , Proteínas Nucleares

RESUMO

The nuclear pore complexes on the nuclear membrane serve as the exclusive gateway for communication between the nucleus and the cytoplasm, regulating the transport of various molecules, including nucleic acids and proteins. The present work investigates the kinetics of the transport of negatively charged graphene quantum dots through nuclear membranes, focusing on quantifying their transport characteristics. Experiments are carried out in permeabilized HeLa cells using time-lapse confocal fluorescence microscopy. Our findings indicate that negatively charged graphene quantum dots exhibit rapid transport to the nuclei, involving two distinct transport pathways in the translocation process. Complementary experiments on the nuclear import and export of graphene quantum dots validate the bi-directionality of transport, as evidenced by comparable transport rates. The study also shows that the negatively charged graphene quantum dots possess favorable retention properties, underscoring their potential as drug carriers.

Assuntos

Transporte Ativo do Núcleo Celular , Núcleo Celular , Grafite , Pontos Quânticos , Pontos Quânticos/química , Pontos Quânticos/metabolismo , Humanos , Grafite/química , Células HeLa , Núcleo Celular/metabolismo , Membrana Nuclear/metabolismo , Poro Nuclear/metabolismo , Microscopia Confocal

RESUMO

Mutations in the nuclear envelope (NE) protein lamin A/C (encoded by LMNA), cause a severe form of dilated cardiomyopathy (DCM) with early-onset life-threatening arrhythmias. However, molecular mechanisms underlying increased arrhythmogenesis in LMNA-related DCM (LMNA-DCM) remain largely unknown. Here we show that a frameshift mutation in LMNA causes abnormal Ca2+ handling, arrhythmias and disformed NE in LMNA-DCM patient-specific iPSC-derived cardiomyocytes (iPSC-CMs). Mechanistically, lamin A interacts with sirtuin 1 (SIRT1) where mutant lamin A/C accelerates degradation of SIRT1, leading to mitochondrial dysfunction and oxidative stress. Elevated reactive oxygen species (ROS) then activates the Ca2+/calmodulin-dependent protein kinase II (CaMKII)-ryanodine receptor 2 (RYR2) pathway and aggravates the accumulation of SUN1 in mutant iPSC-CMs, contributing to arrhythmias and NE deformation, respectively. Taken together, the lamin A/C deficiency-mediated ROS disorder is revealed as central to LMNA-DCM development. Manipulation of impaired SIRT1 activity and excessive oxidative stress is a potential future therapeutic strategy for LMNA-DCM.

Assuntos

Cardiomiopatia Dilatada , Células-Tronco Pluripotentes Induzidas , Lamina Tipo A , Miócitos Cardíacos , Estresse Oxidativo , Espécies Reativas de Oxigênio , Sirtuína 1 , Cardiomiopatia Dilatada/metabolismo , Cardiomiopatia Dilatada/genética , Cardiomiopatia Dilatada/patologia , Lamina Tipo A/metabolismo , Lamina Tipo A/genética , Células-Tronco Pluripotentes Induzidas/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Humanos , Sirtuína 1/metabolismo , Sirtuína 1/genética , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/patologia , Fenótipo , Arritmias Cardíacas/metabolismo , Arritmias Cardíacas/genética , Arritmias Cardíacas/patologia , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/genética , Mutação da Fase de Leitura , Cálcio/metabolismo , Canal de Liberação de Cálcio do Receptor de Rianodina/metabolismo , Canal de Liberação de Cálcio do Receptor de Rianodina/genética , Membrana Nuclear/metabolismo , Mitocôndrias/metabolismo , Masculino , Proteínas Associadas aos Microtúbulos/metabolismo , Proteínas Associadas aos Microtúbulos/genética

RESUMO

Cockayne syndrome (CS) is a premature ageing condition characterized by microcephaly, growth failure, and neurodegeneration. It is caused by mutations in ERCC6 or ERCC8 encoding for Cockayne syndrome B (CSB) and A (CSA) proteins, respectively. CSA and CSB have well-characterized roles in transcription-coupled nucleotide excision repair, responsible for removing bulky DNA lesions, including those caused by UV irradiation. Here, we report that CSA dysfunction causes defects in the nuclear envelope (NE) integrity. NE dysfunction is characteristic of progeroid disorders caused by a mutation in NE proteins, such as Hutchinson-Gilford progeria syndrome. However, it has never been reported in Cockayne syndrome. We observed CSA dysfunction affected LEMD2 incorporation at the NE and increased actin stress fibers that contributed to enhanced mechanical stress to the NE. Altogether, these led to NE abnormalities associated with the activation of the cGAS/STING pathway. Targeting the linker of the nucleoskeleton and cytoskeleton complex was sufficient to rescue these phenotypes. This work reveals NE dysfunction in a progeroid syndrome caused by mutations in a DNA damage repair protein, reinforcing the connection between NE deregulation and ageing.

Assuntos

Síndrome de Cockayne , Enzimas Reparadoras do DNA , Reparo do DNA , Membrana Nuclear , Proteínas de Ligação a Poli-ADP-Ribose , Membrana Nuclear/metabolismo , Humanos , Síndrome de Cockayne/genética , Síndrome de Cockayne/metabolismo , Enzimas Reparadoras do DNA/genética , Enzimas Reparadoras do DNA/metabolismo , Proteínas de Ligação a Poli-ADP-Ribose/metabolismo , Proteínas de Ligação a Poli-ADP-Ribose/genética , Dano ao DNA/genética , DNA Helicases/genética , DNA Helicases/metabolismo , Mutação , Proteínas de Membrana/metabolismo , Proteínas de Membrana/genética , Progéria/genética , Progéria/metabolismo , Proteínas Nucleares/metabolismo , Proteínas Nucleares/genética , Fatores de Transcrição

RESUMO

The Spalt transcriptional regulators participate in a variety of cell fate specification processes during development, regulating transcription through interactions with DNA AT-rich regions. Spalt proteins also bind to heterochromatic regions, and some of their effects require interactions with the NuRD chromatin remodeling and deacetylase complex. Most of the biological roles of Spalt proteins have been characterized in diploid cells engaged in cell proliferation. Here, we address the function of Drosophila Spalt genes in the development of a larval tissue formed by polyploid cells, the prothoracic gland, the cells of which undergo several rounds of DNA replication without mitosis during larval development. We show that prothoracic glands depleted of Spalt expression display severe changes in the size of the nucleolus, the morphology of the nuclear envelope and the disposition of the chromatin within the nucleus, leading to a failure in the synthesis of ecdysone. We propose that loss of ecdysone production in the prothoracic gland of Spalt mutants is primarily caused by defects in nuclear pore complex function that occur as a consequence of faulty interactions between heterochromatic regions and the nuclear envelope.

Assuntos

Proteínas de Drosophila , Ecdisona , Fatores de Transcrição , Animais , Nucléolo Celular/metabolismo , Cromatina/metabolismo , Drosophila/metabolismo , Drosophila/genética , Drosophila melanogaster/metabolismo , Drosophila melanogaster/genética , Drosophila melanogaster/crescimento & desenvolvimento , Proteínas de Drosophila/metabolismo , Proteínas de Drosophila/genética , Ecdisona/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Larva/metabolismo , Larva/crescimento & desenvolvimento , Larva/genética , Mutação/genética , Membrana Nuclear/metabolismo , Membrana Nuclear/genética , Poro Nuclear/metabolismo , Poro Nuclear/genética , Proteínas Repressoras , Fatores de Transcrição/metabolismo , Fatores de Transcrição/genética

RESUMO

Huntington's disease (HD) is caused by a polyglutamine expansion of the huntingtin protein, resulting in the formation of polyglutamine aggregates. The mechanisms of toxicity that result in the complex HD pathology remain only partially understood. Here, we show that nuclear polyglutamine aggregates induce nuclear envelope (NE) blebbing and ruptures that are often repaired incompletely. These ruptures coincide with disruptions of the nuclear lamina and lead to lamina scar formation. Expansion microscopy enabled resolving the ultrastructure of nuclear aggregates and revealed polyglutamine fibrils sticking into the cytosol at rupture sites, suggesting a mechanism for incomplete repair. Furthermore, we found that NE repair factors often accumulated near nuclear aggregates, consistent with stalled repair. These findings implicate nuclear polyQ aggregate-induced loss of NE integrity as a potential contributing factor to Huntington's disease and other polyglutamine diseases.

Assuntos

Doença de Huntington , Membrana Nuclear , Peptídeos , Membrana Nuclear/metabolismo , Membrana Nuclear/ultraestrutura , Humanos , Peptídeos/metabolismo , Peptídeos/genética , Doença de Huntington/metabolismo , Doença de Huntington/patologia , Doença de Huntington/genética , Animais , Proteína Huntingtina/metabolismo , Proteína Huntingtina/genética , Agregados Proteicos , Lâmina Nuclear/metabolismo , Lâmina Nuclear/ultraestrutura , Núcleo Celular/metabolismo

RESUMO

Mitosis exhibits astonishing evolutionary plasticity, with dividing eukaryotic cells differing in the organization of the mitotic spindle and the extent of nuclear envelope breakdown. A new study suggests that a multinucleated lifestyle may favor the evolution of closed nuclear division.

Assuntos

Evolução Biológica , Mitose , Fuso Acromático , Mitose/fisiologia , Fuso Acromático/fisiologia , Animais , Membrana Nuclear/metabolismo , Membrana Nuclear/fisiologia

RESUMO

The autophagy-lysosomal pathway enables the controlled degradation of cellular contents. Nucleophagy is the selective autophagic recycling of nuclear components upon delivery to the lysosome. Although methods to monitor and quantify autophagy as well as selective types of autophagy have been developed and implemented in cells and in vivo, methods monitoring nucleophagy remain scarce. Here, we describe a procedure to monitor the autophagic engagement of an endogenous nuclear envelope component, i.e., ANC-1, the nematode homologue of the mammalian Nesprins in vivo, utilizing super-resolution microscopy.

Assuntos

Proteínas de Caenorhabditis elegans , Caenorhabditis elegans , Animais , Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/genética , Autofagia/fisiologia , Lisossomos/metabolismo , Membrana Nuclear/metabolismo , Núcleo Celular/metabolismo , Macroautofagia

RESUMO

The endosomal sorting complex required for transport (ESCRT) machinery is composed of an articulated architecture of proteins that assemble at multiple cellular sites. The ESCRT machinery is involved in pathways that are pivotal for the physiology of the cell, including vesicle transport, cell division, and membrane repair. The subunits of the ESCRT I complex are mainly responsible for anchoring the machinery to the action site. The ESCRT II subunits function to bridge and recruit the ESCRT III subunits. The latter are responsible for finalizing operations that, independently of the action site, involve the repair and fusion of membrane edges. In this review, we report on the data related to the activity of the ESCRT machinery at two sites: the nuclear membrane and the midbody and the bridge linking cells in the final stages of cytokinesis. In these contexts, the machinery plays a significant role for the protection of genome integrity by contributing to the control of the abscission checkpoint and to nuclear envelope reorganization and correlated resilience. Consistently, several studies show how the dysfunction of the ESCRT machinery causes genome damage and is a codriver of pathologies, such as laminopathies and cancer.

Assuntos

Complexos Endossomais de Distribuição Requeridos para Transporte , Complexos Endossomais de Distribuição Requeridos para Transporte/metabolismo , Complexos Endossomais de Distribuição Requeridos para Transporte/genética , Humanos , Citocinese , Animais , Membrana Nuclear/metabolismo , Instabilidade Genômica

RESUMO

BACKGROUND: The nuclear envelope (NE), which is composed of the outer and inner nuclear membranes, the nuclear pore complex and the nuclear lamina, regulates a plethora of cellular processes, including those that restrict cancer development (genomic stability, cell cycle regulation, and cell migration). Thus, impaired NE is functionally related to tumorigenesis, and monitoring of NE alterations is used to diagnose cancer. However, the chronology of NE changes occurring during cancer evolution and the connection between them remained to be precisely defined, due to the lack of appropriate cell models. METHODS: The expression and subcellular localization of NE proteins (lamins A/C and B1 and the inner nuclear membrane proteins emerin and ß-dystroglycan [ß-DG]) during prostate cancer progression were analyzed, using confocal microscopy and western blot assays, and a prostate cancer cell system comprising RWPE-1 epithelial prostate cells and several prostate cancer cell lines with different invasiveness. RESULTS: Deformed nuclei and the mislocalization and low expression of lamin A/C, lamin B1, and emerin became more prominent as the invasiveness of the prostate cancer lines increased. Suppression of lamin A/C expression was an early event during prostate cancer evolution, while a more extensive deregulation of NE proteins, including ß-DG, occurred in metastatic prostate cells. CONCLUSIONS: The RWPE-1 cell line-based system was found to be suitable for the correlation of NE impairment with prostate cancer invasiveness and determination of the chronology of NE alterations during prostate carcinogenesis. Further study of this cell system would help to identify biomarkers for prostate cancer prognosis and diagnosis.

Assuntos

Lamina Tipo A , Lamina Tipo B , Proteínas de Membrana , Membrana Nuclear , Proteínas Nucleares , Neoplasias da Próstata , Masculino , Humanos , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/patologia , Neoplasias da Próstata/genética , Membrana Nuclear/metabolismo , Linhagem Celular Tumoral , Proteínas de Membrana/metabolismo , Lamina Tipo B/metabolismo , Lamina Tipo A/metabolismo , Lamina Tipo A/genética , Proteínas Nucleares/metabolismo , Proteínas Nucleares/genética , Distroglicanas/metabolismo , Regulação Neoplásica da Expressão Gênica , Núcleo Celular/metabolismo

RESUMO

Chromosomal instability (CIN) generates micronuclei-aberrant extranuclear structures that catalyze the acquisition of complex chromosomal rearrangements present in cancer. Micronuclei are characterized by persistent DNA damage and catastrophic nuclear envelope collapse, which exposes DNA to the cytoplasm. We found that the autophagic receptor p62/SQSTM1 modulates micronuclear stability, influencing chromosome fragmentation and rearrangements. Mechanistically, proximity of micronuclei to mitochondria led to oxidation-driven homo-oligomerization of p62, limiting endosomal sorting complex required for transport (ESCRT)-dependent micronuclear envelope repair by triggering autophagic degradation. We also found that p62 levels correlate with increased chromothripsis across human cancer cell lines and with increased CIN in colorectal tumors. Thus, p62 acts as a regulator of micronuclei and may serve as a prognostic marker for tumors with high CIN.

Assuntos

Autofagia , Instabilidade Cromossômica , Cromotripsia , Neoplasias Colorretais , Micronúcleos com Defeito Cromossômico , Proteína Sequestossoma-1 , Humanos , Proteína Sequestossoma-1/metabolismo , Proteína Sequestossoma-1/genética , Neoplasias Colorretais/genética , Neoplasias Colorretais/patologia , Neoplasias Colorretais/metabolismo , Linhagem Celular Tumoral , Dano ao DNA , Complexos Endossomais de Distribuição Requeridos para Transporte/metabolismo , Complexos Endossomais de Distribuição Requeridos para Transporte/genética , Mitocôndrias/metabolismo , Mitocôndrias/genética , Membrana Nuclear/metabolismo

RESUMO

Chromosome-containing micronuclei are a hallmark of aggressive cancers. Micronuclei frequently undergo irreversible collapse, exposing their enclosed chromatin to the cytosol. Micronuclear rupture catalyzes chromosomal rearrangements, epigenetic abnormalities, and inflammation, yet mechanisms safeguarding micronuclear integrity are poorly understood. In this study, we found that mitochondria-derived reactive oxygen species (ROS) disrupt micronuclei by promoting a noncanonical function of charged multivesicular body protein 7 (CHMP7), a scaffolding protein for the membrane repair complex known as endosomal sorting complex required for transport III (ESCRT-III). ROS retained CHMP7 in micronuclei while disrupting its interaction with other ESCRT-III components. ROS-induced cysteine oxidation stimulated CHMP7 oligomerization and binding to the nuclear membrane protein LEMD2, disrupting micronuclear envelopes. Furthermore, this ROS-CHMP7 pathological axis engendered chromosome shattering known to result from micronuclear rupture. It also mediated micronuclear disintegrity under hypoxic conditions, linking tumor hypoxia with downstream processes driving cancer progression.

Assuntos

Complexos Endossomais de Distribuição Requeridos para Transporte , Proteínas de Membrana , Micronúcleos com Defeito Cromossômico , Neoplasias , Proteínas Nucleares , Estresse Oxidativo , Humanos , Hipóxia Celular , Cromatina/metabolismo , Cisteína/metabolismo , Complexos Endossomais de Distribuição Requeridos para Transporte/metabolismo , Proteínas de Membrana/metabolismo , Proteínas de Membrana/genética , Mitocôndrias/metabolismo , Neoplasias/genética , Neoplasias/metabolismo , Neoplasias/patologia , Membrana Nuclear/metabolismo , Proteínas Nucleares/metabolismo , Proteínas Nucleares/genética , Oxirredução , Espécies Reativas de Oxigênio/metabolismo , Células HeLa

RESUMO

Oxidative damage triggers micronuclear membrane rupture and defective repair.

Assuntos

Neoplasias , Estresse Oxidativo , Humanos , Neoplasias/genética , Reparo do DNA , Membrana Nuclear/metabolismo , Dano ao DNA