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1.
Med Sci Monit ; 26: e920520, 2020 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-32188838

RESUMO

BACKGROUND Freshly isolated mouse embryonic fibroblasts (MEFs) have great proliferation capacity but quickly enter senescent state after several rounds of cell cycle, a process called premature senescence. Cellular senescence can be induced by various stresses such as telomere erosion, DNA damage, and oncogenic signaling. But the contribution of other molecules, such as growth factors, to cellular senescence is incompletely understood. This study aimed to compare the gene expression difference between non-senescent and senescent MEFs to identify the key molecule(s) involved in the spontaneous senescence of MEFs. MATERIAL AND METHODS Primary MEFs were isolated from E12.5 pregnant C57/BL6 mice. The cells were continuously cultured in Dulbecco's Modified Eagle Medium for 9 passages. SA-ß-Gal staining was used as an indicator of cell senescence. The supernatant from primary MEFs (P1 medium) or Passage 6 MEFs (P6 medium) were used to culture freshly isolated MEFs to observe the effects on cell senescence state. Gene expression profiles of primary and senescent MEFs were investigated by RNA-Seq to find the key genes involved in cell senescence. Adipocyte differentiation assay was used to evaluate the stemness of MEFs cultured in FGF2-stimulated medium. RESULTS The senescence of MEFs cultured in the P1 medium was alleviated when compared to the P6 medium. Downregulation of FGF2 expression was revealed by RNA-Seq and further confirmed by real-time quantitative polymerase chain reaction and western blot. FGF2-stimulated medium also had anti-senescence function and could maintain the differentiation ability of MEFs. CONCLUSIONS The premature senescence of MEFs was at least partially caused by FGF2 deficiency. Exogenous FGF2 could alleviate the senescent phenotype.


Assuntos
Senescência Celular/fisiologia , Fator 2 de Crescimento de Fibroblastos/metabolismo , Fibroblastos/metabolismo , Animais , Diferenciação Celular , Proliferação de Células , Dano ao DNA , Embrião de Mamíferos/metabolismo , Feminino , Perfilação da Expressão Gênica , Camundongos , Camundongos Endogâmicos C57BL , Gravidez , Reação em Cadeia da Polimerase em Tempo Real , Transdução de Sinais
2.
Med Sci Monit ; 26: e921887, 2020 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-32191680

RESUMO

BACKGROUND Recent studies have suggested that hepatocyte senescence could contribute to hepatic steatosis and its progression in nonalcoholic fatty liver disease (NAFLD). However, the underlying mechanism causing hepatocyte senescence in this pathological condition is still unclear. A thorough understanding of the mechanism could provide a new target for therapeutic intervention. The purpose of this study was to investigate the role of p66shc in hepatocyte senescence and hepatocyte damage in NAFLD progression. MATERIAL AND METHODS We examined the expression levels of hepatic p66shc and senescence markers in rats and humans with NAFLD, and we assessed the effect of p66shc knockdown or overexpression on senescence and steatosis in human liver cells. RESULTS In this study, we showed that increased hepatic p66shc expression was consistent with upregulated expression of the following senescence markers in NAFLD rats: heterochromatin protein-1-beta (HP1ß), p16, p21, and p53. Furthermore, senescence and steatosis could be induced in hepatoblastoma cell line (HepG2) cells when cells were stimulated with a low concentration of H2O2, and this effect was significantly alleviated by knockdown of p66shc. However, overexpression of p66shc could promote senescence and steatosis in L02 cells. Finally, increased hepatic p66shc protein levels correlated with enhanced expression of the senescence marker p21 and mirrored the degree of disease severity in NAFLD patients. CONCLUSIONS Our findings indicated that the increase in hepatocyte senescence and steatosis in NAFLD may be caused by the upregulation of p66shc expression, implying that strategies for p66shc-mediated regulation of hepatocyte senescence may provide new therapeutic tools for NAFLD.


Assuntos
Senescência Celular , Fígado Gorduroso/patologia , Hepatopatia Gordurosa não Alcoólica/patologia , Animais , Senescência Celular/fisiologia , Progressão da Doença , Fígado Gorduroso/metabolismo , Células Hep G2 , Hepatócitos/metabolismo , Humanos , Hepatopatia Gordurosa não Alcoólica/metabolismo , Ratos , Transdução de Sinais , Proteína 1 de Transformação que Contém Domínio 2 de Homologia de Src
3.
Genes Dev ; 34(5-6): 428-445, 2020 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-32001510

RESUMO

Cellular senescence is a potent tumor suppressor mechanism but also contributes to aging and aging-related diseases. Senescence is characterized by a stable cell cycle arrest and a complex proinflammatory secretome, termed the senescence-associated secretory phenotype (SASP). We recently discovered that cytoplasmic chromatin fragments (CCFs), extruded from the nucleus of senescent cells, trigger the SASP through activation of the innate immunity cytosolic DNA sensing cGAS-STING pathway. However, the upstream signaling events that instigate CCF formation remain unknown. Here, we show that dysfunctional mitochondria, linked to down-regulation of nuclear-encoded mitochondrial oxidative phosphorylation genes, trigger a ROS-JNK retrograde signaling pathway that drives CCF formation and hence the SASP. JNK links to 53BP1, a nuclear protein that negatively regulates DNA double-strand break (DSB) end resection and CCF formation. Importantly, we show that low-dose HDAC inhibitors restore expression of most nuclear-encoded mitochondrial oxidative phosphorylation genes, improve mitochondrial function, and suppress CCFs and the SASP in senescent cells. In mouse models, HDAC inhibitors also suppress oxidative stress, CCF, inflammation, and tissue damage caused by senescence-inducing irradiation and/or acetaminophen-induced mitochondria dysfunction. Overall, our findings outline an extended mitochondria-to-nucleus retrograde signaling pathway that initiates formation of CCF during senescence and is a potential target for drug-based interventions to inhibit the proaging SASP.


Assuntos
Núcleo Celular/patologia , Senescência Celular/fisiologia , Cromatina/patologia , Citoplasma/patologia , Mitocôndrias/patologia , Transdução de Sinais , Animais , Núcleo Celular/fisiologia , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Inibidores de Histona Desacetilases/farmacologia , Humanos , Inflamação/fisiopatologia , Sistema de Sinalização das MAP Quinases/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/fisiologia , Espécies Reativas de Oxigênio/metabolismo , Proteína 1 de Ligação à Proteína Supressora de Tumor p53/metabolismo
4.
PLoS Biol ; 18(1): e3000599, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31945054

RESUMO

The senescence-associated secretory phenotype (SASP) has recently emerged as a driver of and promising therapeutic target for multiple age-related conditions, ranging from neurodegeneration to cancer. The complexity of the SASP, typically assessed by a few dozen secreted proteins, has been greatly underestimated, and a small set of factors cannot explain the diverse phenotypes it produces in vivo. Here, we present the "SASP Atlas," a comprehensive proteomic database of soluble proteins and exosomal cargo SASP factors originating from multiple senescence inducers and cell types. Each profile consists of hundreds of largely distinct proteins but also includes a subset of proteins elevated in all SASPs. Our analyses identify several candidate biomarkers of cellular senescence that overlap with aging markers in human plasma, including Growth/differentiation factor 15 (GDF15), stanniocalcin 1 (STC1), and serine protease inhibitors (SERPINs), which significantly correlated with age in plasma from a human cohort, the Baltimore Longitudinal Study of Aging (BLSA). Our findings will facilitate the identification of proteins characteristic of senescence-associated phenotypes and catalog potential senescence biomarkers to assess the burden, originating stimulus, and tissue of origin of senescent cells in vivo.


Assuntos
Envelhecimento/metabolismo , Biomarcadores/metabolismo , Senescência Celular/fisiologia , Proteoma/análise , Via Secretória/fisiologia , Biomarcadores/análise , Células Cultivadas , Bases de Dados de Proteínas , Exossomos/química , Exossomos/metabolismo , Feminino , Humanos , Fenótipo , Proteoma/metabolismo , Proteômica
5.
Cell Mol Life Sci ; 77(5): 789-805, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31897543

RESUMO

Age-related macular degeneration (AMD) is a complex eye disease underlined by the death of photoreceptors and degeneration of retinal pigment epithelium (RPE) and choriocapillaris (CC). The mechanism(s) responsible for massive and progressive retinal degeneration is not completely known. Senescence, a state of permanent inhibition of cell growth, may be induced by many factors important for AMD pathogenesis and results in senescence-associated secretory phenotype (SASP) that releases growth factors, cytokines, chemokines, proteases and other molecules inducing inflammation and other AMD-related effects. These effects can be induced in the affected cell and neighboring cells, leading to progression of AMD phenotype. Senescent cells also release reactive oxygen species that increase SASP propagation. Many other pathways of senescence-related AMD pathogenesis, including autophagy, the cGAS-STING signaling, degeneration of CC by membrane attack complex, can be considered. A2E, a fluorophore present in lipofuscin, amyloid-beta peptide and humanin, a mitochondria-derived peptide, may link AMD with senescence. Further studies on senescence in AMD pathogenesis to check the possibility of opening a perspective of the use of drugs killing senescent cells (senolytics) and terminating SASP bystander effects (senostatics) might be beneficial for AMD that at present is an incurable disease.


Assuntos
Senescência Celular/fisiologia , Corioide/patologia , Degeneração Macular/patologia , Células Fotorreceptoras/patologia , Epitélio Pigmentado da Retina/patologia , Transtornos da Visão/patologia , Proliferação de Células/fisiologia , Humanos , Espécies Reativas de Oxigênio/metabolismo
6.
Nat Commun ; 11(1): 481, 2020 01 24.
Artigo em Inglês | MEDLINE | ID: mdl-31980643

RESUMO

Vascular senescence is thought to play a crucial role in an ageing-associated decline of organ functions; however, whether vascular senescence is causally implicated in age-related disease remains unclear. Here we show that endothelial cell (EC) senescence induces metabolic disorders through the senescence-associated secretory phenotype. Senescence-messaging secretomes from senescent ECs induced a senescence-like state and reduced insulin receptor substrate-1 in adipocytes, which thereby impaired insulin signaling. We generated EC-specific progeroid mice that overexpressed the dominant negative form of telomeric repeat-binding factor 2 under the control of the Tie2 promoter. EC-specific progeria impaired systemic metabolic health in mice in association with adipose tissue dysfunction even while consuming normal chow. Notably, shared circulation with EC-specific progeroid mice by parabiosis sufficiently transmitted the metabolic disorders into wild-type recipient mice. Our data provides direct evidence that EC senescence impairs systemic metabolic health, and thus establishes EC senescence as a bona fide risk for age-related metabolic disease.


Assuntos
Senescência Celular , Resistência à Insulina , Progéria/metabolismo , Progéria/patologia , Adipócitos Brancos/metabolismo , Adipócitos Brancos/patologia , Tecido Adiposo Branco/metabolismo , Tecido Adiposo Branco/patologia , Animais , Senescência Celular/genética , Senescência Celular/fisiologia , Modelos Animais de Doenças , Células Endoteliais/metabolismo , Células Endoteliais/patologia , Resistência à Insulina/genética , Resistência à Insulina/fisiologia , Interleucina-1alfa/metabolismo , Camundongos , Camundongos Transgênicos , Estresse Oxidativo , Progéria/genética , Regiões Promotoras Genéticas , Receptor TIE-2/genética , Transdução de Sinais , Proteína 2 de Ligação a Repetições Teloméricas/deficiência , Proteína 2 de Ligação a Repetições Teloméricas/genética , Proteína 2 de Ligação a Repetições Teloméricas/metabolismo
7.
Cell Mol Life Sci ; 77(2): 213-229, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31414165

RESUMO

In contrast to the well-recognized replicative and stress-induced premature senescence of normal somatic cells, mechanisms and clinical implications of senescence of cancer cells are still elusive and uncertain from patient-oriented perspective. Moreover, recent years provided multiple pieces of evidence that cancer cells may undergo senescence not only in response to chemotherapy or ionizing radiation (the so-called therapy-induced senescence) but also spontaneously, without any external insults. Since the molecular nature of the latter process is poorly recognized, the significance of spontaneously senescent cancer cells for tumor progression, therapy effectiveness, and patient survival is purely speculative. In this review, we summarize the most up-to-date research regarding therapy-induced and spontaneous senescence of cancer cells, by delineating the most important discoveries regarding the occurrence of these phenomena in vivo and in vitro. This review provides data collected from studies on various cancer cell models, and the narration is presented from the broader perspective of the most critical findings regarding the senescence of normal somatic cells.


Assuntos
Senescência Celular/fisiologia , Neoplasias/patologia , Animais , Humanos
8.
Nat Commun ; 10(1): 5688, 2019 12 12.
Artigo em Inglês | MEDLINE | ID: mdl-31831736

RESUMO

Senescence is induced by various stimuli such as oncogene expression and telomere shortening, referred to as oncogene-induced senescence (OIS) and replicative senescence (RS), respectively, and accompanied by global transcriptional alterations and 3D genome reorganization. Here, we demonstrate that the human condensin II complex participates in senescence via gene regulation and reorganization of euchromatic A and heterochromatic B compartments. Both OIS and RS are accompanied by A-to-B and B-to-A compartmental transitions, the latter of which occur more frequently and are undergone by 14% (430 Mb) of the human genome. Mechanistically, condensin is enriched in A compartments and implicated in B-to-A transitions. The full activation of senescence genes (SASP genes and p53 targets) requires condensin; its depletion impairs senescence markers. This study describes that condensin reinforces euchromatic A compartments and promotes B-to-A transitions, both of which are coupled to optimal expression of senescence genes, thereby allowing condensin to contribute to senescent processes.


Assuntos
Adenosina Trifosfatases/metabolismo , Adenosina Trifosfatases/farmacologia , Senescência Celular/genética , Senescência Celular/fisiologia , Proteínas de Ligação a DNA/metabolismo , Proteínas de Ligação a DNA/farmacologia , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Complexos Multiproteicos/metabolismo , Complexos Multiproteicos/farmacologia , Proteínas de Ciclo Celular/genética , Linhagem Celular , Cromatina , Perfilação da Expressão Gênica , Técnicas de Silenciamento de Genes , Genômica , Humanos , Proteínas Nucleares/genética , Oncogenes , Regiões Promotoras Genéticas , Encurtamento do Telômero , Proteína Supressora de Tumor p53/genética
9.
Invest Ophthalmol Vis Sci ; 60(14): 4583-4595, 2019 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-31675075

RESUMO

Purpose: Trabecular meshwork (TM) cells detect and coordinate responses to intraocular pressure (IOP) in the eye. TM cells become dysfunctional in glaucoma where IOP is often elevated. Recently, we showed that normal TM (NTM) cells communicate by forming tubular connections called tunneling nanotubes (TNTs). Here, we investigated TNTs in glaucomatous TM (GTM) cells. Methods: Primary GTM and NTM cells were established from cadaver eyes. Transfer of Vybrant DiO and DiD-labeled vesicles via TNT connections was measured. Imaris software measured the number and length of cell protrusions from immunofluorescent confocal images. Live-cell imaging of the actin cytoskeleton was performed. The distribution of myosin-X, a regulator of TNTs/filopodia, was investigated in TM cells and tissue. Results: GTM cells contained significantly more transferred fluorescent vesicles than NTM cells (49.6% vs. 35%). Although NTM cells had more protrusions at the cell surface than GTM cells (7.61 vs. 4.65 protrusions/cell), GTM protrusions were significantly longer (12.1 µm vs. 9.76 µm). Live-cell imaging demonstrated that the GTM actin cytoskeleton was less dynamic, and vesicle transfer between cells was significantly slower than NTM cells. Furthermore, rearrangement of the actin cortex adjacent to the TNT may influence TNT formation. Myosin-X immunostaining was punctate and disorganized in GTM cells and tissue compared to age-matched NTM controls. Conclusions: Together, our data demonstrate that GTM cells have phenotypic and functional differences in their TNTs. Significantly slower vesicle transfer via TNTs in GTM cells may delay the timely propagation of cellular signals when pressures become elevated in glaucoma.


Assuntos
Citoesqueleto de Actina/metabolismo , Glaucoma de Ângulo Aberto/patologia , Miosinas/metabolismo , Nanotubos , Pseudópodes/metabolismo , Malha Trabecular/patologia , Western Blotting , Tamanho Celular , Células Cultivadas , Senescência Celular/fisiologia , Densitometria , Glaucoma de Ângulo Aberto/metabolismo , Humanos , Microscopia Confocal , Fagocitose/fisiologia , Fenótipo , Transdução de Sinais/fisiologia , Malha Trabecular/metabolismo
10.
Invest Ophthalmol Vis Sci ; 60(14): 4643-4651, 2019 11 01.
Artigo em Inglês | MEDLINE | ID: mdl-31682715

RESUMO

Purpose: Conjunctivochalasis (CCH) is a common ocular disease and has received extensive attention recently. However, its exact pathogenesis remains largely unknown. Owing to the high morbidity of CCH in older people, this study aimed to investigate whether cellular senescence contributes to CCH progression and the underlying mechanism. Methods: Loose conjunctival tissues from CCH patients (n = 13) and normal conjunctival tissues from age-matched persons (n = 12) were obtained and the fibroblasts were separately induced and obtained. Cellular senescence, and the expression of senescence-associated genes (p53 and p21) and p38 in CCH conjunctival tissues and normal controls, were determined by senescence-associated ß-galactosidase (SA-ß-Gal) staining and quantitative (q)RT-PCR, respectively. To explore the effects of p38 on cellular senescence in CCH fibroblasts, small interfering RNA (siRNA) targeting p38 (siP38) and p38-specific inhibitor SB203580 was performed in CCH fibroblasts. Then, cellular senescence, cell viability, reactive oxygen species (ROS) production, and gene expression were detected according to the corresponding methods. Results: CCH conjunctival tissues had significantly more senescent cells, evidenced by more SA-ß-Gal-positive cells, and higher expression of senescence-associated genes (p53 and p21) and p38. CCH fibroblasts transfected with siP38 or treated with SB203580 had obviously reduced numbers of senescent cells, decreased ROS production, and increased cell viability, as well as reduced expression of senescence-associated genes. Meanwhile, blocking p38 signaling decreased the expression of p53 and p21. Conclusions: Therefore, these findings indicate that cellular senescence might be a causative factor for CCH. P38 signaling might play an important role in the progress of cellular senescence in CCH fibroblasts via manipulation of p53/p21 signaling.


Assuntos
Senescência Celular/fisiologia , Doenças da Túnica Conjuntiva/enzimologia , Fibroblastos/enzimologia , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismo , Western Blotting , Contagem de Células , Proliferação de Células , Células Cultivadas , Doenças da Túnica Conjuntiva/patologia , Inibidores Enzimáticos/farmacologia , Fibroblastos/efeitos dos fármacos , Humanos , Imidazóis/farmacologia , Piridinas/farmacologia , RNA Interferente Pequeno/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Transdução de Sinais , Superóxido Dismutase/metabolismo , beta-Galactosidase/metabolismo
11.
Nat Neurosci ; 22(11): 1806-1819, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31636448

RESUMO

Prediabetes and Alzheimer's disease both increase in prevalence with age. The former is a risk factor for the latter, but a mechanistic linkage between them remains elusive. We show that prediabetic serum hyperinsulinemia is reflected in the cerebrospinal fluid and that this chronically elevated insulin renders neurons resistant to insulin. This leads to abnormal electrophysiological activity and other defects. In addition, neuronal insulin resistance reduces hexokinase 2, thus impairing glycolysis. This hampers the ubiquitination and degradation of p35, favoring its cleavage to p25, which hyperactivates CDK5 and interferes with the GSK3ß-induced degradation of ß-catenin. CDK5 contributes to neuronal cell death while ß-catenin enters the neuronal nucleus and re-activates the cell cycle machinery. Unable to successfully divide, the neuron instead enters a senescent-like state. These findings offer a direct connection between peripheral hyperinsulinemia, as found in prediabetes, age-related neurodegeneration and cognitive decline. The implications for neurodegenerative conditions such as Alzheimer's disease are described.


Assuntos
Envelhecimento/fisiologia , Ciclo Celular/fisiologia , Senescência Celular/fisiologia , Hiperinsulinismo/fisiopatologia , Resistência à Insulina/fisiologia , Neurônios/fisiologia , Animais , Morte Celular/fisiologia , Senescência Celular/efeitos dos fármacos , Quinase 5 Dependente de Ciclina/metabolismo , Potenciais Pós-Sinápticos Excitadores/fisiologia , Expressão Gênica/efeitos dos fármacos , Glicólise/efeitos dos fármacos , Hexoquinase/metabolismo , Hiperinsulinismo/líquido cefalorraquidiano , Potenciais Pós-Sinápticos Inibidores/fisiologia , Insulina/farmacologia , Liraglutida/farmacologia , Masculino , Aprendizagem em Labirinto/fisiologia , Metformina/farmacologia , Camundongos , Neurônios/metabolismo , Fosfotransferases/metabolismo , Cultura Primária de Células , Proteínas Serina-Treonina Quinases/metabolismo , Ubiquitinação/fisiologia , beta Catenina/metabolismo
12.
Invest Ophthalmol Vis Sci ; 60(13): 4436-4450, 2019 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-31652328

RESUMO

Purpose: The purpose of this study was to systematically characterize and correlate the transcriptome and DNA methylome signatures of mouse Müller cells that may underlie the development, physiological functions, and regeneration capacity of these cells. Methods: Mouse Müller cells under normal, injury, and aging conditions were sorted from Müller cell-specific green fluorescent protein (GFP)-expressing mice. RNA sequencing was used to sequence transcriptomes, and reduced representation bisulfite sequencing was used to sequence DNA methylomes. Various bioinformatics tools were used to compare and correlate the transcriptomes and DNA methylomes. Results: Müller cells express a distinct transcriptome that is in line with their retinal supporting roles and dormant retinogenic status. Injury changes the Müller cell transcriptome dramatically but fails to stimulate the cell cycle machinery and retinogenic factors to the states observed in early retinal progenitor cells (RPCs). Müller cells exhibit a less methylated genome than that of early RPCs, but most regulatory elements for Müller cell- and RPC-specific genes are similarly hypomethylated in both Müller cells and RPCs, except for a subset of Müller cell-specific functional genes. Aging only subtly affects the transcriptome and DNA methylome of Müller cells. Conclusions: Failure to reactivate the cell cycle machinery and retinogenic factors to necessary levels might be key barriers blocking Müller cells from entering an RPC-like regeneration state. DNA methylation might regulate the expression of a subset of Müller cell-specific functional genes during development but is likely not involved in restricting the regeneration activity of Müller cells.


Assuntos
Senescência Celular/fisiologia , Células Ependimogliais/metabolismo , Traumatismos Oculares/metabolismo , Neuroglia/metabolismo , Retina/lesões , Transcriptoma/genética , Animais , Ilhas de CpG/genética , Metilação de DNA , Citometria de Fluxo , Camundongos , Camundongos Endogâmicos C57BL , Reação em Cadeia da Polimerase , Regeneração/fisiologia , Células-Tronco/metabolismo
13.
Nature ; 574(7779): 553-558, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31645721

RESUMO

Age-associated chronic inflammation (inflammageing) is a central hallmark of ageing1, but its influence on specific cells remains largely unknown. Fibroblasts are present in most tissues and contribute to wound healing2,3. They are also the most widely used cell type for reprogramming to induced pluripotent stem (iPS) cells, a process that has implications for regenerative medicine and rejuvenation strategies4. Here we show that fibroblast cultures from old mice secrete inflammatory cytokines and exhibit increased variability in the efficiency of iPS cell reprogramming between mice. Variability between individuals is emerging as a feature of old age5-8, but the underlying mechanisms remain unknown. To identify drivers of this variability, we performed multi-omics profiling of fibroblast cultures from young and old mice that have different reprogramming efficiencies. This approach revealed that fibroblast cultures from old mice contain 'activated fibroblasts' that secrete inflammatory cytokines, and that the proportion of activated fibroblasts in a culture correlates with the reprogramming efficiency of that culture. Experiments in which conditioned medium was swapped between cultures showed that extrinsic factors secreted by activated fibroblasts underlie part of the variability between mice in reprogramming efficiency, and we have identified inflammatory cytokines, including TNF, as key contributors. Notably, old mice also exhibited variability in wound healing rate in vivo. Single-cell RNA-sequencing analysis identified distinct subpopulations of fibroblasts with different cytokine expression and signalling in the wounds of old mice with slow versus fast healing rates. Hence, a shift in fibroblast composition, and the ratio of inflammatory cytokines that they secrete, may drive the variability between mice in reprogramming in vitro and influence wound healing rate in vivo. This variability may reflect distinct stochastic ageing trajectories between individuals, and could help in developing personalized strategies to improve iPS cell generation and wound healing in elderly individuals.


Assuntos
Envelhecimento/metabolismo , Reprogramação Celular , Senescência Celular/fisiologia , Fibroblastos/metabolismo , Cicatrização , Animais , Linhagem Celular , Reprogramação Celular/efeitos dos fármacos , Meios de Cultivo Condicionados/farmacologia , Citocinas/metabolismo , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Humanos , Células-Tronco Pluripotentes Induzidas/citologia , Células-Tronco Pluripotentes Induzidas/efeitos dos fármacos , Células-Tronco Pluripotentes Induzidas/metabolismo , Mediadores da Inflamação/metabolismo , Judeus/genética , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Análise de Sequência de RNA , Transdução de Sinais/efeitos dos fármacos , Análise de Célula Única , Processos Estocásticos , Fatores de Tempo , Cicatrização/efeitos dos fármacos
14.
Biochemistry (Mosc) ; 84(8): 896-904, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31522671

RESUMO

RNA editing by adenosine deaminases of the ADAR family attracts a growing interest of researchers, both zoologists studying ecological and evolutionary plasticity of invertebrates and medical biochemists focusing on the mechanisms of cancer and other human diseases. These enzymes deaminate adenosine residues in the double-stranded (ds) regions of RNA with the formation of inosine. As a result, some RNAs change their three-dimensional structure and functions. Adenosine-to-inosine editing in the mRNA coding sequences may cause amino acid substitutions in the encoded proteins. Here, we reviewed current concepts on the functions of two active ADAR isoforms identified in mammals (including humans). The ADAR1 protein, which acts non-specifically on extended dsRNA regions, is capable of immunosuppression via inactivation of the dsRNA interactions with specific sensors inducing the cell immunity. Expression of a specific ADAR1 splicing variant is regulated by the type I interferons by the negative feedback mechanism. It was shown that immunosuppressing effects of ADAR1 facilitate progression of some types of cancer. On the other hand, changes in the amino acid sequences resulting from the mRNA editing by the ADAR enzymes can result in the formation of neoantigens that can activate the antitumor immunity. The ADAR2 isoform acts on RNA more selectively; its function is associated with the editing of mRNA coding regions and can lead to the amino acid substitutions, in particular, those essential for the proper functioning of some neurotransmitter receptors in the central nervous system.


Assuntos
Adenosina Desaminase/metabolismo , Carcinogênese/metabolismo , Plasticidade Neuronal/fisiologia , Edição de RNA/fisiologia , Proteínas de Ligação a RNA/metabolismo , Adenosina Desaminase/imunologia , Sequência de Aminoácidos , Animais , Senescência Celular/fisiologia , Humanos , Inosina/metabolismo , Interferon Tipo I/metabolismo , Proteoma/metabolismo , RNA de Cadeia Dupla/metabolismo , Proteínas de Ligação a RNA/imunologia
15.
Invest Ophthalmol Vis Sci ; 60(10): 3669-3679, 2019 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-31469894

RESUMO

Purpose: To investigate the presence and role of fibroblast senescence in the dynamic process of corneal wound healing involving stromal cell apoptosis, proliferation, and differentiation. Methods: An in vivo corneal wound healing model was performed using epithelial debridement in C57BL/6 mice. The corneas were stained using TUNEL, Ki67, and α-smooth muscle actin (α-SMA) as markers of apoptosis, proliferation, and myofibroblastic differentiation, respectively. Cellular senescence was confirmed by senescence-associated ß-galactosidase (SA-ß-gal) staining and P16Ink4a expression. Mitogenic response and gene expression were compared among normal fibroblasts, H2O2-induced senescent fibroblasts, and TGF-ß-induced myofibroblasts in vitro. The senescence was further detected in mouse models of corneal scarring, alkali burn, and penetrating keratoplasty (PKP). Results: The apoptosis and proliferation of corneal stromal cells were found to peak at 4 and 24 hours after epithelial debridement. Positive staining of SA-ß-gal was observed clearly in the anterior stromal cells at 3 to 5 days. The senescent cells displayed P16Ink4a+ vimentin+ α-SMA+, representing the major origin of activated corneal resident fibroblasts. Compared with normal fibroblasts and TGF-ß-induced myofibroblasts, H2O2-induced senescent fibroblasts showed a nonfibrogenic phenotype, including a reduced response to growth factor basic fibroblast growth factor (bFGF) or platelet-derived growth factor-BB (PDGF-BB), increased matrix metalloproteinase (MMP)1/3/13 expression, and decreased fibronectin and collagen I expression. Moreover, cellular senescence was commonly found in the mouse corneal scarring, alkali burn, and PKP models. Conclusions: Corneal epithelial debridement induced the senescence of corneal fibroblasts after apoptosis and proliferation. The senescent cells displayed a nonfibrogenic phenotype and may be involved in the self-limitation of corneal fibrosis.


Assuntos
Senescência Celular/fisiologia , Lesões da Córnea/fisiopatologia , Fibroblastos/citologia , Cicatrização/fisiologia , Actinas/metabolismo , Animais , Apoptose , Western Blotting , Proliferação de Células , Lesões da Córnea/metabolismo , Fibroblastos/metabolismo , Citometria de Fluxo , Peróxido de Hidrogênio/toxicidade , Marcação In Situ das Extremidades Cortadas , Antígeno Ki-67/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Reação em Cadeia da Polimerase em Tempo Real , Hidróxido de Sódio/toxicidade
16.
Transl Psychiatry ; 9(1): 198, 2019 08 21.
Artigo em Inglês | MEDLINE | ID: mdl-31434875

RESUMO

Recent evidence suggests a significant overlap in biological changes between major depression and aging across the lifespan. We aim to evaluate the impact of a major depressive episode on the Senescence-Associated Secretory Phenotype (SASP) index, a dynamic secretory molecular pattern indicative of cellular senescence. We also tested the potential moderators of the association between major depression and the SASP index. We included 1165 young and middle-aged adults (527 with a current major depressive episode (cMDE) and 638 with no lifetime history of depression) from a community-based cohort from the Netherlands. We calculated the SASP index based on a previously developed composite index involving 19 biomarkers. cMDE had higher SASP index values (t(1163) = 2.93, p = 0.003) compared to controls in the univariate analysis. After controlling for sociodemographic and somatic health covariates, there was no significant association between cMDE and SASP index (F(1,1158) = 1.09, p = 0.29). Those with the most severe depressive episodes had significantly higher SASP indices compared to those with mild-to-moderate cMDE and controls (F(2,1162) = 6.73, p = 0.001). We found a significant interaction between cMDE and overweight (F(1,1164) = 5.1, p = 0.028): those with comorbid cMDE and overweight had the highest SASP index. Our study demonstrated a complex interaction between cMDE and medical morbidity, especially overweight, on the SASP index, suggesting that their coexistence aggravate age-related biological processes. Moreover, higher SASP index can be a biomarker for more severe depressive episodes.


Assuntos
Senescência Celular/fisiologia , Transtorno Depressivo Maior/metabolismo , Adulto , Dano ao DNA/fisiologia , Transtorno Depressivo Maior/diagnóstico , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Índice de Gravidade de Doença
17.
Nature ; 571(7765): 398-402, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31292548

RESUMO

A decline in stem cell function impairs tissue regeneration during ageing, but the role of the stem-cell-supporting niche in ageing is not well understood. The small intestine is maintained by actively cycling intestinal stem cells that are regulated by the Paneth cell niche1,2. Here we show that the regenerative potential of human and mouse intestinal epithelium diminishes with age owing to defects in both stem cells and their niche. The functional decline was caused by a decrease in stemness-maintaining Wnt signalling due to production of Notum, an extracellular Wnt inhibitor, in aged Paneth cells. Mechanistically, high activity of mammalian target of rapamycin complex 1 (mTORC1) in aged Paneth cells inhibits activity of peroxisome proliferator activated receptor α (PPAR-α)3, and lowered PPAR-α activity increased Notum expression. Genetic targeting of Notum or Wnt supplementation restored function of aged intestinal organoids. Moreover, pharmacological inhibition of Notum in mice enhanced the regenerative capacity of aged stem cells and promoted recovery from chemotherapy-induced damage. Our results reveal a role of the stem cell niche in ageing and demonstrate that targeting of Notum can promote regeneration of aged tissues.


Assuntos
Envelhecimento , Senescência Celular , Esterases/metabolismo , Mucosa Intestinal/patologia , Celulas de Paneth/metabolismo , Regeneração , Envelhecimento/fisiologia , Animais , Senescência Celular/fisiologia , Esterases/antagonistas & inibidores , Esterases/biossíntese , Feminino , Humanos , Mucosa Intestinal/fisiologia , Masculino , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Camundongos , PPAR alfa/metabolismo , Celulas de Paneth/patologia , Receptores Acoplados a Proteínas-G/metabolismo , Nicho de Células-Tronco , Células-Tronco/patologia , Proteínas Wnt/antagonistas & inibidores , Via de Sinalização Wnt
18.
Life Sci ; 232: 116639, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31295472

RESUMO

AIMS: Sirtuins have been implicated in the aging process, however, the functions of SIRT2 in post-maturation aging of oocytes are not fully understood. The purpose of the present investigation was to assess the roles of SIRT2 in aged oocytes and mechanisms involved. MAIN METHODS: The fresh MII oocytes were aging in vitro, and treated with SIRT2 inhibitor (SirReal2), autophagy activator (Rapamycin), and autophagy inhibitor (3-Ma) for 24 h, respectively. Oocyte activation, cytoplasmic fragmentation, and spindle defects, mitochondrial distribution, ROS levels, ATP production, mitochondrial membrane potential, and early apoptosis were investigated. Western blotting was performed to determine LC3-II accumulation, SQSTM1 degradation, and caspase-3 activity. KEY FINDINGS: SIRT2 expression gradually decreased in a time-dependent manner during oocyte aging. Treatment with SirReal2 significantly increased the rates of oocyte activation, cytoplasmic fragmentation, and spindle defects. In particular, the high ROS levels, abnormal mitochondrial distribution, low ATP production, and lost ΔΨm were observed in SirReal2-exposed oocytes. Further analysis revealed that LC3-II accumulation and SQSTM1 degradation were induced by SIRT2 inhibition. By performing early apoptosis analysis showed that oocyte aging was accompanied with cellular apoptosis, and SIRT2 inhibition increased apoptosis rates of aged oocytes. Importantly, upregulating autophagy with Rapamycin could mimic the effects of SIRT2 inhibition on apoptosis by increasing caspase-3 activation, whereas downregulating autophagy with 3-MA could abolish those effects by blocking caspase-3 activation. SIGNIFICANCE: Our results suggest that SIRT2 inactivation is a key mechanism underlying of cellular aging, and SIRT2 inhibition contributes to autophagy-dependent cellular apoptosis in post-maturation oocytes.


Assuntos
Oócitos/fisiologia , Sirtuína 2/fisiologia , Acetamidas/farmacologia , Animais , Apoptose/efeitos dos fármacos , Apoptose/fisiologia , Autofagia/efeitos dos fármacos , Autofagia/fisiologia , Bovinos , Senescência Celular/efeitos dos fármacos , Senescência Celular/fisiologia , Feminino , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Mitocôndrias/efeitos dos fármacos , Oócitos/classificação , Oócitos/efeitos dos fármacos , Oócitos/metabolismo , Sirolimo/farmacologia , Sirtuína 2/antagonistas & inibidores , Sirtuína 2/metabolismo , Tiazóis/farmacologia
19.
Genes (Basel) ; 10(7)2019 07 09.
Artigo em Inglês | MEDLINE | ID: mdl-31324014

RESUMO

Research on longevity and healthy aging promises to increase our lifespan and decrease the burden of degenerative diseases with important social and economic effects. Many aging theories have been proposed, and important aging pathways have been discovered. Model organisms have had a crucial role in this process because of their short lifespan, cheap maintenance, and manipulation possibilities. Yeasts, worms, fruit flies, or mammalian models such as mice, monkeys, and recently, dogs, have helped shed light on aging processes. Genes and molecular mechanisms that were found to be critical in simple eukaryotic cells and species have been confirmed in humans mainly by the functional analysis of mammalian orthologues. Here, we review conserved aging mechanisms discovered in different model systems that are implicated in human longevity as well and that could be the target of anti-aging interventions in human.


Assuntos
Longevidade , Modelos Biológicos , Envelhecimento/fisiologia , Animais , Biomarcadores , Senescência Celular/fisiologia , Drosophila , Eucariotos/fisiologia , Humanos , Longevidade/genética , Longevidade/imunologia , Mamíferos , Modelos Animais , Transdução de Sinais , Leveduras/fisiologia
20.
Life Sci ; 232: 116582, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31220525

RESUMO

AIMS: Vascular calcification/aging can cause different kind of serious diabetic vascular complications. High glucose could induce vascular smooth muscle cells (VSMCs) calcification/aging and then lead to diabetes-related vascular calcification/aging. In this study, we investigated how information in the blood is transmitted to VSMCs and the mechanisms of VSMCs calcification/aging under hyperglycaemic conditions. MATERIALS AND METHODS: Transmission electron microscopy and molecular size analysis were used to assess the morphology and size of exosomes. Alizarin Red S staining and senescence-associated ß galactosidase (SA-ß-gal) staining were carried out to detect calcification and senescence in VSMCs, respectively. Proteomics analysis was carried out to detect the different expression of exosomal proteins. Protein levels were measured by western blot analysis. KEY FINDINGS: The results show that exosomes isolated from high glucose stimulated human umbilical vein endothelial cell (HG-HUVEC-Exo) exhibited a bilayer structure morphology with a mean diameter of 63.63 ±â€¯2.96 nm. The presence of exosome markers including CD9, CD63 and TSG101 were also detected in HG-HUVEC-Exo. High glucose could induce VSMCs calcification/aging by increasing the expression of osteocalcin (OC) and p21 as well as the formation of mineralised nodules and SA-ß-gal positive cells. Fluorescence microscopy verified that the exosomes were taken up by VSMCs and Notch3 protein was enriched in HG-HUVEC-Exo. Most importantly, mTOR signalling was closely related to Notch3 protein and was involved in regulating HG-HUVEC-Exo-induced VSMCs calcification/aging. SIGNIFICANCE: The data demonstrate that Notch3 is required for HG-HUVEC-Exo promoted VSMCs calcification/aging and regulates VSMCs calcification/aging through the mTOR signalling pathway.


Assuntos
Músculo Liso Vascular/metabolismo , Receptor Notch3/fisiologia , Calcificação Vascular/metabolismo , Calcificação Fisiológica/efeitos dos fármacos , Cálcio/metabolismo , Células Cultivadas , Senescência Celular/fisiologia , Complicações do Diabetes/metabolismo , Complicações do Diabetes/fisiopatologia , Células Endoteliais/metabolismo , Células Endoteliais/fisiologia , Exossomos/metabolismo , Glucose/metabolismo , Células Endoteliais da Veia Umbilical Humana/metabolismo , Humanos , Hiperglicemia/metabolismo , Músculo Liso Vascular/fisiologia , Miócitos de Músculo Liso/metabolismo , Osteocalcina/metabolismo , Receptor Notch3/metabolismo , Transdução de Sinais/efeitos dos fármacos , Calcificação Vascular/fisiopatologia
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