Importancia biológica de los telómeros / Biological importance of telomeres

Se exponen los hallazgos históricos y la importancia biológica de los telómeros en la vida celular y en los aspectos genéticos del ADN humano. (AU)

The discovery and the biological importance of the telomeres are exposed. (AU)

Genética y genómica de la longevidad y el envejecimiento / Genetics and genomics of longevity and aging

El envejecimiento y la longevidad son procesos que involucran una serie de factores genéticos, bioquímicos y ambientales. En esta revisión se tratan algunas cuestiones sobre estos dos procesos biológicos y epigenéticos. Se presentan los genes más importantes en estos procesos, así como se ejemplifican enfermedades que presentan un aceleramiento o falla en la longevidad y el envejecimiento. Se usa el análisis inteligente de datos para hallar interacciones de proteínas/genes que expliquen estos dos fenómenos biológicos.

Aging and longevity are processes that involve a series of genetic, biochemical and environmental factors. This review addresses some issues about these two biological and epigenetic processes. The most important genes in these processes are presented, as well as diseases that present an acceleration or failure in longevity and aging. Intelligent data analysis is used to find protein/gene interactions that explain these two biological phenomena.

Características e efeitos de programas de exercício físico para idosos durante a pandemia de COVID-19: revisão integrativa / Characteristics and effects of physical exercise programs for older adults during the COVID-19 pandemic: an integrative review

Objetivo: Avaliar as características de programas de exercício físico para idosos e seus efeitos durante a pandemia de COVID-19. Métodos: revisão integrativa, realizada entre os meses de janeiro a março de 2022. As buscas foram realizadas no MEDLINE via PubMed, Lilacs via BVS, PEDro e Cochrane Library. Foram incluídos artigos experimentais (ensaios clínicos randomizados, ensaios não randomizados ou estudos quase-experimentais) publicados de 2019 a 2021, sem restrição de idioma, e que utilizaram programas de exercício físico para idosos (> 60 anos) em sua intervenção. A seleção dos estudos foi realizada através da leitura de título e resumo, e seguida da leitura do texto completo. Os artigos selecionados tiveram seus resultados extraídos com auxílio de um formulário on-line, tabulados com a utilização de planilha eletrônica e analisados qualitativa e quantitativamente. Resultados: Foram identificados 113 estudos; 7 preencheram os critérios de elegibilidade e foram incluídos na revisão, todos ensaios clínicos randomizados. Os programas de exercícios foram em maior frequência, multicomponente (resistência, equilíbrio, flexibilidade e aeróbico), entregues de forma on -line, sendo realizados de 2 a 7 vezes na semana, com duração entre 30 e 50 min. Efeitos significativos foram observados na função física, composição corporal, triglicerídeo sanguíneo, incidência de quedas, atividade física e capacidade funcional.Conclusões: Os programas de exercício físico utilizados durante a pandemia da COVID-19 apresentaram resultados promissores para a população idosa, se mostrando uma alternativa viável para a manutenção das funções físicas, mentais e cognitivas dos idosos em momentos de calamidade pública.

Objective: To evaluate the characteristics of physical exercise programs for older adults and their effects during the COVID-19 pandemic. Methods: An integrative review was conducted between January and March 2022. A search was conducted in MEDLINE via PubMed, Lilacs via BVS, PEDro, and Cochrane Library. Experimental articles (randomized clinical trials, non-randomized trials, or quasi-experimental studies) published from 2019 to 2021, with no language restriction, and that used physical exercise programs for older adults (> 60 years) in their intervention were included. The studies were selected by reading the title, abstract, and full text. The selected articles had their results extracted using an online form, tabulated using an electronic spreadsheet, and analyzed qualitatively and quantitatively. Results: 113 studies were identified; 7 met the eligibility criteria and were included in the review, all randomized controlled trials. The multi-component exercise programs were more frequent (resistance, balance, flexibility, and aerobic), delivered remotelyand performed 2 to 7 times a week, lasting between 30 and 50 minutes. Significant effects were observed on physical function, body composition, blood triglycerides, the incidence of falls, physical activity, and functional capacity. Conclusions: The physical exercise programs used during the COVID-19 pandemic showed promising results for older adults. The programs proved to be a viable alternative for maintaining the physical, mental, and cognitive functions of older adults in times of public calamity.

Pathophysiological implications of cellular senescence and prospects for novel anti-aging drugs / 生理学报

Chronological aging is the leading risk factor for human diseases, while aging at the cellular level, namely cellular senescence, is the fundamental driving force of organismal aging. The impact of cellular senescence on various life processes, including normal physiology, organismal aging and the progress of various age-related pathologies, has been largely ignored for a long time. However, with recent advancement in relevant fields, cellular senescence has become the core of aging biology and geriatric medicine. Although senescent cells play important roles in physiological processes including tissue repair, wound healing, and embryonic development, they can also contribute to tissue dysfunction, organ degeneration and various pathological conditions during adulthood. Senescent cells exert paracrine effects on neighboring cells in tissue microenvironments by developing a senescence-associated secretory phenotype, thus maintaining long-term and active intercellular communications that ultimately results in multiple pathophysiological effects. This is regarded as one of the most important discoveries in life science of this century. Notably, selective elimination of senescent cells through inducing their apoptosis or specifically inhibiting the senescence-associated secretory phenotype has shown remarkable potential in preclinical and clinical interventions of aging and age-related diseases. This reinforces the belief that senescent cells are the key drug target to alleviate various aging syndromes. However, senescent cells exhibit heterogeneity in terms of form, function and tissue distribution, and even differ among species, which presents a challenge for the translation of significant research achievements to clinical practice in future. This article reviews and discusses the characteristics of senescent cells, current targeting strategies and future trends, providing useful and valuable references for the rapidly blooming aging biology and geriatric medicine.

4E-BP1 counteracts human mesenchymal stem cell senescence via maintaining mitochondrial homeostasis

Although the mTOR-4E-BP1 signaling pathway is implicated in aging and aging-related disorders, the role of 4E-BP1 in regulating human stem cell homeostasis remains largely unknown. Here, we report that the expression of 4E-BP1 decreases along with the senescence of human mesenchymal stem cells (hMSCs). Genetic inactivation of 4E-BP1 in hMSCs compromises mitochondrial respiration, increases mitochondrial reactive oxygen species (ROS) production, and accelerates cellular senescence. Mechanistically, the absence of 4E-BP1 destabilizes proteins in mitochondrial respiration complexes, especially several key subunits of complex III including UQCRC2. Ectopic expression of 4E-BP1 attenuates mitochondrial abnormalities and alleviates cellular senescence in 4E-BP1-deficient hMSCs as well as in physiologically aged hMSCs. These f indings together demonstrate that 4E-BP1 functions as a geroprotector to mitigate human stem cell senescence and maintain mitochondrial homeostasis, particularly for the mitochondrial respiration complex III, thus providing a new potential target to counteract human stem cell senescence.

Multiple characteristic alterations and available therapeutic strategies of cellular senescence / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Given its state of stable proliferative inhibition, cellular senescence is primarily depicted as a critical mechanism by which organisms delay the progression of carcinogenesis. Cells undergoing senescence are often associated with the alteration of a series of specific features and functions, such as metabolic shifts, stemness induction, and microenvironment remodeling. However, recent research has revealed more complexity associated with senescence, including adverse effects on both physiological and pathological processes. How organisms evade these harmful consequences and survive has become an urgent research issue. Several therapeutic strategies targeting senescence, including senolytics, senomorphics, immunotherapy, and function restoration, have achieved initial success in certain scenarios. In this review, we describe in detail the characteristic changes associated with cellular senescence and summarize currently available countermeasures.

NEK2 promotes the progression of liver cancer by resisting the cellular senescence / 中南大学学报(医学版)

OBJECTIVES@#Liver cancer is the sixth most common malignant tumor in the world. Hepatocellular carcinoma (HCC) accounts for 85%-90% of all patients with liver cancer. It possesses the characteristics of insidious onset, rapid progression, early recurrence, easy drug resistance, and poor prognosis. NIMA related kinase 2 (NEK2) is a cell cycle regulating kinases, which regulates cell cycle in mitosis. Cellular senescence is a complex heterogeneous process, and is a stable form of cell cycle arrest that limits the proliferative potential of cells. This study aims to investigate the relationship between the expression level of NEK2 and the senescence in hepatoma cells, and to explore the effect of NEK2 expression on hepatoma cell senescence and the underlying molecular mechanism.@*METHODS@#A total of 581 senescence-relevant genes were obtained from the GenAge website. The gene expression data of tumor tissues of 370 HCC patients were downloaded from the Cancer Genome Atlas database. The co-expression of NEK2 and aging-related genes was analyzed by R-package. KEGG was used to analyze the significant gene enrichment pathway of differentially expressed genes in NEK2 overexpression HEK293. The stable transfected cell lines with overexpression and knockdown of NEK2 were constructed in hepatoma cell line SMMC-7721 and HepG2, and senescence-associated β-galactosidase (SA-β-gal) staining was used to detect senescence, the cell proliferation was detected by CCK-8 method and clone formation experiment, the cell cycle was analyzed by flow cytometry, and the expression of proteins related to p53/p21, p16/Rb, and phosphatase and tensin homolog deleted on chromosome ten (PTEN)/Akt signal transduction pathway was detected by Western blotting.@*RESULTS@#There were 320 senescence related genes co-expressed with NEK2. KEGG analysis showed that the senescence signaling pathway was significantly enriched in HEK293 cells with overexpression of NEK2.Compared with SMMC-7721 or HepG2 without knockdown of NEK2, the senescent cells of SMMC-7721 and HepG2 with knockdown of NEK2 were increased, cell proliferation and clone formation were decreased significantly, the percentage of cells in G0/G1 phase was increased, the expression levels of phospho-Akt (p-Akt) and phospho-Rb (p-Rb) protein were decreased significantly, and the expression level of p16 protein was increased significantly (all P<0.05). Compared with SMMC-7721 or HepG2 transfected with blank plasmid, the senescent cells of SMMC-7721 and HepG2 overexpressing NEK2 were decreased, the cell proliferation and clone formation were increased significantly, the percentage of cells in G0/G1 phase were decreased, the expression levels of p-Akt and p-Rb protein were increased significantly, and the expression level of p16 protein was decreased significantly (all P<0.05).@*CONCLUSIONS@#NEK2 may mediate the anti-aging effect of hepatoma cells through p16/Rb and PTEN/Akt signal transduction pathways, which provides a new theoretical basis for NEK2 to promote the progress of liver cancer and a new idea for the targeting treatment for liver cancer.

Advances in relationship between cell senescence and atherosclerosis / 浙江大学学报·医学版

Cellular senescence is a biological process associated with the degeneration of cell structure and function, which contribute to age-related diseases. Atherosclerosis is a chronic inflammatory disease that can cause a variety of cardiovascular disorders. In this article, we review the effects of cellular senescence on the development of atherosclerosis through diverse physiopathological changes, focusing on the alterations in senescent organelles and the increased senescence-associated secretory phenotype (SASP), and exploring the relevant therapeutic strategies for atherosclerosis by clearing senescent cells and reducing SASP, to provide new insights for the treatment of atherosclerosis.

Interleukin-13 promotes cellular senescence through inducing mitochondrial dysfunction in IgG4-related sialadenitis / 国际口腔科学杂志·英文版

Immunoglobulin G4-related sialadenitis (IgG4-RS) is an immune-mediated fibro-inflammatory disease and the pathogenesis is still not fully understood. The aim of this study was to explore the role and mechanism of interleukin-13 (IL-13) in the cellular senescence during the progress of IgG4-RS. We found that the expression of IL-13 and IL-13 receptor α1 (IL-13Rα1) as well as the number of senescent cells were significantly higher in the submandibular glands (SMGs) of IgG4-RS patients. IL-13 directly induced senescence as shown by the elevated activity of senescence-associated β-galactosidase (SA-β-gal), the decreased cell proliferation, and the upregulation of senescence markers (p53 and p16) and senescence-associated secretory phenotype (SASP) factors (IL-1β and IL-6) in SMG-C6 cells. Mechanistically, IL-13 increased the level of phosphorylated signal transducer and activator of transcription 6 (p-STAT6) and mitochondrial-reactive oxygen species (mtROS), while decreased the mitochondrial membrane potential, ATP level, and the expression and activity of superoxide dismutase 2 (SOD2). Notably, the IL-13-induced cellular senescence and mitochondrial dysfunction could be inhibited by pretreatment with either STAT6 inhibitor AS1517499 or mitochondria-targeted ROS scavenger MitoTEMPO. Moreover, IL-13 increased the interaction between p-STAT6 and cAMP-response element binding protein (CREB)-binding protein (CBP) and decreased the transcriptional activity of CREB on SOD2. Taken together, our findings revealed a critical role of IL-13 in the induction of salivary gland epithelial cell senescence through the elevated mitochondrial oxidative stress in a STAT6-CREB-SOD2-dependent pathway in IgG4-RS.

Research progress of lung aging in chronic respiratory diseases / 生理学报

Cell aging is an extremely complex process, which is characterized by mitochondrial structural dysfunction, telomere shortening, inflammatory microenvironment, protein homeostasis imbalance, epigenetic changes, abnormal DNA damage and repair, etc. Aging is usually accompanied by structural and functional damage of tissues and organs which further induces the occurrence and development of aging-related diseases. Aging includes physiological aging caused by increased age and pathological aging induced by a variety of factors. Noteworthy, as a target organ directly contacting with the outside air, lung is more prone to various stimuli, causing pathological premature aging which is lung aging. Studies have found that there is a certain proportion of senescent cells in the lungs of most chronic respiratory diseases. However, the underlying mechanism by which these senescent cells induce lung senescence and their role in chronic respiratory diseases is still obscure. This paper focuses on the causes and classification of lung aging, the internal mechanism of lung aging involved in chronic respiratory diseases, and the application of anti-aging treatments in chronic respiratory diseases. We hope to provide new research ideas and theoretical basis for the clinical prevention and treatment in chronic respiratory diseases.

Progress in replicative senescence of mesenchymal stem cells regulated by microenvironment / 生理学报

Mesenchymal stem cells (MSCs) are a class of pluripotent cells that can self-renew and differentiate. Numerous studies have shown that MSCs have important roles in areas such as regenerative medicine and tissue engineering. However, it is worth noting that MSCs will gradually age during long-term in vitro expansion with decreased stemness such as weakened migration ability, slowed proliferation rate and decreased differentiation potential, which greatly hinders the application of MSCs. Currently, the microenvironment for cell growth is recognized as one of the factors causing senescence in MSCs. Recent studies point out that the latest technologies such as exogenous administration, oxygen concentration regulation and extracellular matrix (ECM) construction can delay stem cell senescence by simulating or regulating the microenvironment. Here, we review the current knowledge of the characteristics and molecular mechanisms of senescent MSCs and microenvironment strategies to maintain MSCs stemness, which can provide a reference for future large-scale application of MSCs preparations in tissue engineering and clinical studies.

Research Advances on the Senescence Mechanism of Bone Marrow Mesenchymal Stem Cells Derived from Patients with Myelodysplastic Syndrome--Review / 中国实验血液学杂志

Emerging data have demonstrated that bone marrow mesenchymal stem cells (MSCs) play important roles in the progression of myelodysplastic syndrome (MDS). Experiments in vitro have showed that MSCs derived from MDS patients (MDS-MSC) exhibit the biological characteristics of cell senescence. Although the underlying mechanisms that regulate cell senescence need to be further elucidated, existing researches indicate that the mechanisms of MDS-MSC senescence have significant heterogeneity. Depth understanding of the underlying mechanisms involved in cell senescence of MDS-MSC are crucial to explore the potential therapeutic target of MDS. Therefore, this review summarizes research advances related with MSC senescence, such as MDS-MSC intrinsic changes in telomere shortening, DNA methylation status, oxidative stress and signal pathways regulating cell senescence in recent years.

Mechanism of extract of Ginseng Radix et Rhizoma, Notoginseng Radix et Rhizoma and Chuanxiong Rhizoma on SIRT1 autophagy pathway of endothelial cell senescence induced by hydrogen peroxide / 中国中药杂志

This study aims to explore the effect of extract of Ginseng Radix et Rhizoma, Notoginseng Radix et Rhizoma, and Chuanxiong Rhizoma(hereinafter referred to as GNS) on the SIRT1-autophagy pathway of endothelial cell senescence induced by hydrogen peroxide(H_2O_2). To be specific, vascular endothelial cells were classified into the blank control group(control), model group(model), model + DMSO group(DMSO), resveratrol group(RESV), and GNS low-dose(GNS-L), medium-dose(GNS-M), and high-dose(GNS-H) groups. They were treated with H_2O_2 for senescence induction except the control. After intervention of cells in each group with corresponding drugs for 24 h, cell growth status was observed under an inverted microscope, and the formation of autophagosome under the transmission electron microscope. In addition, the changes of microtubule-associated protein 1 light chain 3β(LC3 B) were detected by immunofluorescence staining. The autophagy flux was tracked with the autophagy double-labeled adenovirus(mRFP-GFP-LC3) fusion protein. Dansylcadaverine(MDC) staining was employed to determine the autophagic vesicles, and Western blot the expression of sirtuin 1(SIRT1), ubiquitin-binding protein p62, and LC3Ⅱ. After H_2O_2 induction, cells demonstrated slow growth, decreased adhesion ability, raised number of SA-β-gal-stained blue ones, a certain number of autophagosomes with bilayer membrane and secondary lysosomes in the cytoplasm, and slight rise of autophagy flux level. Compared with the model group, GNS groups showed improved morphology, moderate adhesion ability, complete and smooth membrane, decreased SA-β-gal-stained blue cells, many autophagosomes, autophagic vesicles, and secondary lysosomes in the cytoplasm, increased autophagolysosomes, autophagy flux level, and fluorescence intensity of LC3 B and MDC, up-regulated expression of SIRT1 and LC3Ⅱ, and down-regulated expression of p62, suggesting the improvement of autophagy level. GNS can delay the senescence of vascular endothelial cells. After the intervention, the autophagy flux and related proteins SIRT1, LC3Ⅱand p62 changed significantly, and the autophagy level increased significantly. However, EX527 weakened the effect of Chinese medicine in delaying vascular senescence. GNS may delay the senescence of vascular endothelial cells through the SIRT1 autophagy pathway.

Diabetes fuels periodontal lesions via GLUT1-driven macrophage inflammaging / 国际口腔科学杂志·英文版

Hyperglycemia induces chronic low-grade inflammation (inflammaging), which is a newly identified contributor to diabetes-related tissue lesions, including the inflammatory bone loss in periodontitis. It is also a secondary senescent pattern mediated by an increased burden of senescent cells and senescence-associated secretory phenotype (SASP). Macrophage is a key SASP-spreading cell and may contribute to the maintenance of SASP response in the periodontal microenvironment. Using a transgenic diabetic model (BLKS/J-Lepr

The role and mechanism of SIRT1 gene in depression / 生理学报

As a kind of mental illness, depression produces great difficulties in clinical diagnosis and treatment, and has a high disability rate. It is urgent to clarify the mechanism of depression to find potential therapeutic targets and effective clinical treatment methods. As a deacetylase, silent mating type information regulator 2 homolog 1 (SIRT1) is involved in many biological processes such as cell aging, cancer, and cardiovascular disease. In recent years, more and more studies have found that SIRT1 gene plays an important role in the pathogenesis of depression, but the mechanism is still unclear. Therefore, this review mainly summarizes the relevant research progress on the role and mechanism of SIRT1 gene in the hippocampus, prefrontal cortex, amygdala, hypothalamic suprachiasmatic nucleus, and nucleus accumbens in depression, in order to provide new ideas for exploring the mechanism and prevention of depression.

Envejecimiento neural, plasticidad cerebral y ejercicio: Avances desde la óptica de fisioterapia / Neural aging, cerebral plasticity and Exercise: Advances from the Physiotherapy´s perspective

El ejercicio ha demostrado efectividad para promover la plasticidad cerebral en los procesos de envejecimiento neural. Esta revisión narrativa de literatura tiene como objetivo analizar el efecto neural del ejercicio para promover la plasticidad cerebral en el envejecimiento. Los resultados incluyeron publicaciones que mencionan los efectos de la plasticidad cerebral mediada por el ejercicio empleando protocolos de ejercicio con duración, intensidad y frecuencia clínicamente significativa. La revisión documental se organizó en tres apartados: a) envejecimiento neural y procesos fisiológicos interrelacionados, b) plasticidad cerebral mediada por el ejercicio, c) ejercicio para promover el envejecimiento neural saludable. Se pudo concluir que el fisioterapeuta, aplicando protocolos de ejercicio, puede promover cambios positivos en la función cerebral lo cual se traducen en la mejoría del desempeño físico y funcional de los adultos mayores..(AU)

Exercise has shown effectiveness in promoting brain plasticity in neural aging processes.This narrative review of literature aims to analyze the neural effect of exercise to promote brain plasticity in aging. The results included publications that mention the effects of brain plasticity mediated by exercise, using exercise protocols with clinically significant duration, intensity and frequency. Through the documentary review three sections were determined: Neural Aging: Interrelated physiological processes; Exercisemediated brain plasticity; Exercise to promote healthy neural aging. It was concluded that the physiotherapist, applying exercise protocols, can promote positive changes in brain function, which translates into an improvement in the physical and functional performance of older adults..(AU)

Comparison of senescence progression in mesenchymal cells from human umbilical cord walls measured by immunofluorescence and flow cytometry of p16 and p21 / Comparação da progressão da senescência em células mesenquimais de parede de cordão umbilical humano medida por imunofluorescência e citometria de fluxo de p16 e p21

ABSTRACT Objective To follow the expansion of mesenchymal stem cells from umbilical cords by two classic senescence markers, p16 (INK4A) and p21 (CDKN1A), using practical, fast, and less expensive methods than the gold standard Western blotting technique, to evaluate its applicability in the laboratory. Methods Mesenchymal stem cells from umbilical cords were isolated from Wharton's jelly and, after quality control, morphological and immunophenotypic characterization by flow cytometry, were expanded in culture until coming close to cell cycle arrest (replicative senescence). Results A comparison was made between young cells, at passage 5, and pre-senescent cells, at passage 10, evaluating the protein expression of the classic cell senescence markers p16 and p21, comparing the results obtained by Western blotting with those obtained by flow cytometry and indirect immunofluorescence. Conclusion Follow-up of cell cultures, through indirect p16 immunofluorescence, allows the identification of mesenchymal stem cells from umbilical cord cultures at risk of reaching replicative senescence.

RESUMO Objetivo Acompanhar a expansão de células-tronco mesenquimais de cordão umbilical por dois marcadores clássicos de senescência, p16 (INK4A) e p21 (CDKN1A), usando métodos práticos, rápidos e com custo menor do que a técnica padrão-ouro de Western blotting, para avaliar sua aplicabilidade em laboratório. Métodos Células-tronco mesenquimais de cordão umbilical foram isoladas da geleia de Wharton e, após controle de qualidade e caracterização morfológica e imunofenotípica por citometria de fluxo, foram expandidas em cultura, até chegarem próximas à parada do ciclo celular (senescência replicativa). Resultados Foi feita a comparação entre células jovens, na passagem 5, e células pré-senescentes, na passagem 10, avaliando a expressão proteica dos marcadores clássicos de senescência celular p16 e p21, comparando os resultados obtidos por Western blotting com os obtidos por citometria de fluxo e imunofluorescência indireta. Conclusão O seguimento de culturas celulares, por meio da imunofluorescência indireta de p16, permite identificar as culturas de células-tronco mesenquimais de cordão umbilical em risco de atingirem a senescência replicativa.

FOXO4 maintains senescence in human umbilical cord mesenchymal stem cells by repressing apoptosis / 生理学报

The purpose of the present study was to investigate the effects of forkhead box O4 (FOXO4) on the senescence of human umbilical cord-derived mesenchymal stem cells (hUC-MSCs). The hUC-MSCs were induced to senescence by natural passage, and FOXO4 expression was inhibited by lentiviral shRNA transfection. The hallmark of cell senescence was analyzed by β-galactosidase staining, and the cell viability was assayed by CCK-8 method. Flow cytometry was used to investigate the apoptosis of hUC-MSCs. The expression levels of Bcl-2, Bax, FOXO4, interleukin 6 (IL-6) and cleaved Caspase-3 were detected by qPCR and Western blot. Immunofluorescence staining was used to detect FOXO4 expression. The amount of IL-6 secreted by hUC-MSCs was detected by ELISA. The results showed that, compared with the passage 1, senescent hUC-MSCs showed up-regulated expression levels of Bax and FOXO4, down-regulated expression levels of Bcl-2 and cleaved Caspase-3, and increased IL-6 mRNA expression and secretion. FOXO4 inhibition in senescent hUC-MSCs promoted cell apoptosis, reduced cell viability, and inhibited the mRNA expression and secretion of IL-6. These results suggest that FOXO4 maintains viability and function of senescent hUC-MSCs by repressing their apoptosis response, thus accelerating senescence of the whole cell colony.

Quercetin-induced apoptosis ameliorates vascular smooth muscle cell senescence through AMP-activated protein kinase signaling pathway

Aging is one of the risk factors for the development of cardiovascular diseases. During the progression of cellular senescence, cells enter a state of irreversible growth arrest and display resistance to apoptosis. As a flavonoid, quercetin induces apoptosis in various cells. Accordingly, we investigated the relationship between quercetin-induced apoptosis and the inhibition of cellular senescence, and determined the mechanism of oxidative stress-induced vascular smooth muscle cell (VSMC) senescence. In cultured VSMCs, hydrogen peroxide (H₂O₂) dose-dependently induced senescence, which was associated with increased numbers of senescence-associated β-galactosidase-positive cells, decreased expression of SMP30, and activation of p53-p21 and p16 pathways. Along with senescence, expression of the anti-apoptotic protein Bcl-2 was observed to increase and the levels of proteins related to the apoptosis pathway were observed to decrease. Quercetin induced apoptosis through the activation of AMP-activated protein kinase. This action led to the alleviation of oxidative stress-induced VSMC senescence. Furthermore, the inhibition of AMPK activation with compound C and siRNA inhibited apoptosis and aggravated VSMC senescence by reversing p53-p21 and p16 pathways. These results suggest that senescent VSMCs are resistant to apoptosis and quercetin-induced apoptosis attenuated the oxidative stress-induced senescence through activation of AMPK. Therefore, induction of apoptosis by polyphenols such as quercetin may be worthy of attention for its anti-aging effects.

Cellular Senescence in Arterial Diseases

Cell-proliferation potency is limited, as cells cannot proceed through the cell cycle continually. Instead, they eventually show an irreversible arrest of proliferation, commonly referred to as cellular senescence. Following the initial discovery of this phenomenon by Hayflick et al., studies have indicated that cells are also destined to undergo aging. In addition to the irreversible termination of proliferation, senescent cells are characterized by a flattened and enlarged morphology. Senescent cells become pro-inflammatory and contribute to the initiation and maintenance of sustained chronic sterile inflammation. Aging is associated with the accumulation of senescent cells in the cardiovascular system, and in general these cells are considered to be pathogenic because they mediate vascular remodeling. Recently, genetic and pharmacological approaches have enabled researchers to eliminate senescent cells both in vitro and in vivo. The term “senolysis” is now used to refer to the depletion of senescent cells, and evidence indicates that senolysis contributes to the reversal of age-related pathogenic phenotypes without the risk of tumorigenesis. The concept of senolysis has opened new avenues in research on aging, and senolysis may be a promising therapeutic approach for combating age-related disorders, including arterial diseases.