Mechanisms Of Cellular Senescence Research Articles

Oxidative stress, aging, antioxidant supplementation and their impact on human health: An overview

Aging is characterized by a progressive loss of tissue and organ function due to genetic and environmental factors, nutrition, and lifestyle. Oxidative stress is one the most important mechanisms of cellular senescence and increased frailty, resulting in several age-linked, noncommunicable diseases. Contributing events include genomic instability, telomere shortening, epigenetic mechanisms, reduced proteome homeostasis, altered stem-cell function, defective intercellular communication, progressive deregulation of nutrient sensing, mitochondrial dysfunction, and metabolic unbalance. These complex events and their interplay can be modulated by dietary habits and the ageing process, acting as potential measures of primary and secondary prevention. Promising nutritional approaches include the Mediterranean diet, the intake of dietary antioxidants, and the restriction of caloric intake. A comprehensive understanding of the ageing processes should promote new biomarkers of risk or diagnosis, but also beneficial treatments oriented to increase lifespan.

Cellular Senescence and Regulated Cell Death of Tubular Epithelial Cells in Diabetic Kidney Disease.

Cellular senescence is frequently evident at etiologic sites of chronic diseases and involves essentially irreversible arrest of cell proliferation, increased protein production, resistance to apoptosis, and altered metabolic activity. Regulated cell death plays a vital role in shaping fully functional organs during the developmental process, coordinating adaptive or non-adaptive responses, and coping with long-term harmful intracellular or extracellular homeostasis disturbances. In recent years, the concept of ‘diabetic tubulopathy’ has emerged. tubular epithelial cells are particularly susceptible to the derangements of diabetic state because of the virtue of the high energy requirements and reliance on aerobic metabolism render. Hyperglycemia, oxidative stress, persistent chronic inflammation, glucose toxicity, advanced glycation end-products (AGEs) accumulation, lipid metabolism disorders, and lipotoxicity contribute to the cellular senescence and different patterns of regulated cell death (apoptosis, autophagic cell death, necroptosis, pyroptosis, and ferroptosis) in tubular epithelial cells. We now explore the ‘tubulocentric’ view of diabetic kidney disease(DKD). And we summarize recent discoveries regarding the development and regulatory mechanisms of cellular senescence, apoptosis, autophagic cell death, necroptosis, pyroptosis, and ferroptosis in the pathogenesis of DKD. These findings provide new perspectives on the mechanisms of DKD and are useful for designing novel therapeutic approaches for the treatment of DKD.

Pharmacological Targeting of Senescence with ABT-263 in Experimental Heart Failure with Preserved Ejection Fraction

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Fundação Ciência e Tecnlogia HFpEF is the most common form of heart disease in the elderly and is associated with high morbidity and mortality. Our understanding of HFpEF pathophysiology is limited and development of efficient therapies that alter the clinical course of the disease has proved greatly challenging. Although aging is a risk factor of HFpEF1, the involvement of aging hallmarks such as cell senescent and immunosenescence is unclear. Recently, a link between endothelial senescence and HFpEF development was demonstrated in mice with accelerated aging [1], endorsing anti-aging pharmacologic as potential new therapeutic alternatives for HFpEF. In fact, the senolytic (drugs that selectively promote apoptosis of senescent cells) ABT-263 has already proven efficacy in the context of cardiovascular diseases. Further studies are needed to clarify the relevance of aging and of anti-aging therapies in the context of HFpEF. Using ZSF1 obese rats (ZSF1-Ob) as model of HFpEF we showed from 18 weeks signs of immunosenescence compared to ZSF1-Ln, namely an increased frequency of circulating myeloid cells and decreased frequency of T and B cells. Concomitantly, expression of pro-inflammatory factors (IL-6, IL-1, TGF-β, TNF-α) was upregulated in peripheral blood mononuclear cells (PBMCs) of ZSF1-Ob which also displayed characteristic features of cell senescence (p21 expression, lysosomal endogenous Beta-galactosidase (SA-B-Gal) senescence-associated secretory phenotype (SASP) and up-regulation of BCL-XL. Importantly, no signs of cellular senescence (SA-B-gal, pH2AX and senescence associated pathways) were found in the main hematopoietic organs (spleen and bone marrow). Alongside, these systemic alterations, an upsurge of cellular senescence was observed in myocardium of ZSF1-Ob rats, particularly in endothelial and hematopoietic cells. Serum of ZSF1-Ob rat was able to induce activation and cellular senescence of cardiac microvascular endothelial cells, indicating that systemic circulating factors may be the upstream mechanism of cellular senescence and dysfunction in HFpEF. Analysis of HFpEF patients and a control cohort adjusted to main co-morbidities further demonstrated accumulation of senescent monocytes in HFpEF patients. In these patients, the senescence marker SA-B-Gal correlated with plasmatic brain natriuretic peptide (BNP) levels and pulmonary artery systolic pressure. Targeting aging hallmarks through the treatment of ZSF1-Ob rat with ABT-263 resulted in a reduction in circulating senescent cells, decreased systemic and local inflammation, re-established immune proportions, restore the levels of circulating BNP and attenuated myocardial remodeling, particularly endothelial dysfunction and fibrosis. Collectively these findings support that premature cellular senescence contributes to the establishment of a deleterious pro-inflammatory environment in HFpEF and that senolytic agents hold promise for the treatment of this syndrome.

Large-scale chromatin reorganization reactivates placenta-specific genes that drive cellular aging.

Nuclear deformation, a hallmark frequently observed in senescent cells, is presumed to be associated with the erosion of chromatin organization at the nuclear periphery. However, how such gradual changes in higher-order genome organization impinge on local epigenetic modifications to drive cellular mechanisms of aging has remained enigmatic. Here, through large-scale epigenomic analyses of isogenic young, senescent, and progeroid human mesenchymal progenitor cells (hMPCs), we delineate a hierarchy of integrated structural state changes that manifest as heterochromatin loss in repressive compartments, euchromatin weakening in active compartments, switching in interfacing topological compartments, and increasing epigenetic entropy. We found that the epigenetic de-repression unlocks the expression of pregnancy-specific beta-1 glycoprotein (PSG) genes that exacerbate hMPC aging and serve as potential aging biomarkers. Our analyses provide a rich resource for uncovering the principles of epigenomic landscape organization and its changes in cellular aging and for identifying aging drivers and intervention targets with a genome-topology-based mechanism.

PD51-03 MOLECULAR CHARACTERISTICS OF METASTATIC TERATOMAS AND MATCHED PRIMARY TESTICULAR GERM CELL TUMORS

You have accessJournal of UrologyCME1 May 2022PD51-03 MOLECULAR CHARACTERISTICS OF METASTATIC TERATOMAS AND MATCHED PRIMARY TESTICULAR GERM CELL TUMORS Anna Savelyeva, Feng Wang, Lei Guo, John Lafin, Liwei Jia, Kirill Medvedev, Cheryl Lewis, Payal Kapur, Vitaly Margulis, Solomon Woldu, Xiaosong Meng, Nick Grishin, James Amatruda, Lin Xu, and Aditya Bagrodia Anna SavelyevaAnna Savelyeva More articles by this author , Feng WangFeng Wang More articles by this author , Lei GuoLei Guo More articles by this author , John LafinJohn Lafin More articles by this author , Liwei JiaLiwei Jia More articles by this author , Kirill MedvedevKirill Medvedev More articles by this author , Cheryl LewisCheryl Lewis More articles by this author , Payal KapurPayal Kapur More articles by this author , Vitaly MargulisVitaly Margulis More articles by this author , Solomon WolduSolomon Woldu More articles by this author , Xiaosong MengXiaosong Meng More articles by this author , Nick GrishinNick Grishin More articles by this author , James AmatrudaJames Amatruda More articles by this author , Lin XuLin Xu More articles by this author , and Aditya BagrodiaAditya Bagrodia More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002622.03AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Metastatic teratoma (MT) is a subtype of germ cell tumor (GCT) characterized by resistance to platinum-based chemotherapy. MT is treated via complete surgical excision, using retroperitoneal lymph node dissection (RPLND), following chemotherapy. Molecular characterization of post-chemotherapy MTs along with pre-chemotherapy testicular primary tumors could reveal 1) the mechanisms of MT development and differentiation, 2) molecular changes associated with platinum-resistance, 3) novel therapeutic options for patients with unresectable MTs. METHODS: We performed whole exome and transcriptome sequencing for 16 primary germ cell tumors and 18 metastatic teratomas, 11 were matched tumor/metastasis pairs. All MTs in our cohort were collected after induction platinum-based chemotherapy. We used VarScan for SNV analysis and PennCNV to detect genomic copy-number variations (CNVs). Metastatic Teratomas were compared to matched primary tumors and primary teratomas characterized by TCGA. RESULTS: Our analysis revealed that metastatic teratomas as well as their tumors of origin had low tumor mutation burden (0.65 and 0.47 accordingly). Amongst 583 SNVs detected in the study cohort, only two (KRAS p.Gly12Asp and KRAS p.Gly12Val) were previously described as oncogenic. Analysis of SNVs in proteins playing key roles in oncogenic signaling showed that TP53 and Ras pathways were the most affected in metastatic teratomas. The majority of metastatic teratomas possess gain of 3p11.1 and loss of 10q26.3, 16p11.2, 19p13.2, 19q12 and 22q12.3 loci. Within 3p11.1 we did not identify any well-known oncodrivers. However, 5 chromosomal loci with lost heterozygosity contained 16 previously annotated tumor suppressor genes: HTRA1, EBF3, FUS, PRKCB, NUPR1, PYCARD, ZNF668, ARMC5, YPEL3, DNMT1, DNAJB1, SMARCA4, GADD45GIP1, MIR199A1, TIMP3, TMPRSS6. Amongst those, GADD45GIP1 inhibition (growth arrest and DNA-damage-inducible, gamma interacting protein 1) is associated with cisplatin resistance development through mechanism of cellular senescence. CONCLUSIONS: Metastatic teratoma in our cohort is characterized by low tumor mutational burden and several recurring copy number changes. Molecular insight of metastatic teratoma may inform disease biology and treatment. Source of Funding: Dedman Scholar Award © 2022 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 207Issue Supplement 5May 2022Page: e843 Advertisement Copyright & Permissions© 2022 by American Urological Association Education and Research, Inc.MetricsAuthor Information Anna Savelyeva More articles by this author Feng Wang More articles by this author Lei Guo More articles by this author John Lafin More articles by this author Liwei Jia More articles by this author Kirill Medvedev More articles by this author Cheryl Lewis More articles by this author Payal Kapur More articles by this author Vitaly Margulis More articles by this author Solomon Woldu More articles by this author Xiaosong Meng More articles by this author Nick Grishin More articles by this author James Amatruda More articles by this author Lin Xu More articles by this author Aditya Bagrodia More articles by this author Expand All Advertisement PDF DownloadLoading ...

Cellular aging and immunity

Science is constantly evolving and updated with current data on cell biology. The cellular aging phenomenon should be considered an evolutionary mechanism of the biological regulation of all living organisms. Factors initiating cellular aging are variable. Each cell type can respond differently to the activation factors of cellular aging. In recent decades, science has been supplemented with new data that provide a deeper understanding of cellular and molecular mechanisms of cellular aging and the formation of immune homeostasis. There is a real prospect of using effective means of its regulation. In recent years, scientists have come close to discovering the mechanisms of cellular aging. Factors and mechanisms of cell regeneration are more deeply revealed. Scientists are also better aware of the phylogeny and ontogenesis of immune processes and the role of immune factors in developing pathologies. Researchers are increasingly focusing on modern diagnostic methods and xenotherapy. However, the specific factors of immunoregulation and the interaction of microphages, macrophages, and lymphocytes with other body cells are not yet fully understood. Accordingly, this requires further in-depth study. This review reviews the current literature on cellular aging and its regulatory mechanisms. The authors also present the results of their research on the mechanisms of immune responses in reproductive pathology. They draw parallels with modern scientific theories and interpret research. We will also focus on the issues that need to be addressed in the near future for the progressive development of this field of science. Thus, the study of the mechanisms of cellular aging and the development of effective means of hay therapy today requires further painstaking work. Despite significant advances in preclinical studies, many questions remain about the practical use of the drugs. This is especially true in the medicine of oncology, neurology, and cardiology. Nevertheless, scientists will be able to use pharmacological agents to influence cell division, differentiation, and determination in the future. We also hope to have developed effective means of immunotherapy of diseases. The molecular mechanisms of cell aging and mediators involved in the mechanisms of cell aging and death are being studied in detail. The field of research contains countless fascinating studies that are sure to be discovered.

Telomeres and Mitochondrial Metabolism: Implications for Cellular Senescence and Age-related Diseases.

Cellular senescence is an irreversible cell arrest process, which is determined by a variety of complicated mechanisms, including telomere attrition, mitochondrial dysfunction, metabolic disorders, loss of protein homeostasis, epigenetic changes, etc. Cellular senescence is causally related to the occurrence and development of age-related disease. The elderly is liable to suffer from disorders such as neurodegenerative diseases, cancer, and diabetes. Therefore, it is increasingly imperative to explore specific countermeasures for the treatment of age-related diseases. Numerous studies on humans and mice emphasize the significance of metabolic imbalance caused by short telomeres and mitochondrial damages in the onset of age-related diseases. Although the experimental data are relatively independent, more and more evidences have shown that there is mutual crosstalk between telomeres and mitochondrial metabolism in the process of cellular senescence. This review systematically discusses the relationship between telomere length, mitochondrial metabolic disorder, as well as their underlying mechanisms for cellular senescence and age-related diseases. Future studies on telomere and mitochondrial metabolism may shed light on potential therapeutic strategies for age-related diseases. Graphical The characteristics of cellular senescence mainly include mitochondrial dysfunction and telomere attrition. Mitochondrial dysfunction will cause mitochondrial metabolic disorders, including decreased ATP production, increased ROS production, as well as enhanced cellular apoptosis. While oxidative stress reaction to produce ROS, leads to DNA damage, and eventually influences telomere length. Under the stimulation of oxidative stress, telomerase catalytic subunit TERT mainly plays an inhibitory role on oxidative stress, reduces the production of ROS and protects telomere function. Concurrently, mitochondrial dysfunction and telomere attrition eventually induce a range of age-related diseases, such as T2DM, osteoporosis, AD, etc. :increase; :reduce;⟝:inhibition.

Measurement of Protein Turnover Rates in Senescent and Non-Dividing Cultured Cells with Metabolic Labeling and Mass Spectrometry

Mounting evidence has shown that the accumulation of senescent cells in the central nervous system contributes to neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. Cellular senescence is a state of permanent cell cycle arrest that typically occurs in response to exposure to sub-lethal stresses. However, like other non-dividing cells, senescent cells remain metabolically active and carry out many functions that require unique transcriptional and translational demands and widespread changes in the intracellular and secreted proteomes. Understanding how protein synthesis and decay rates change during senescence can illuminate the underlying mechanisms of cellular senescence and find potential therapeutic avenues for diseases exacerbated by senescent cells. This paper describes a method for proteome-scale evaluation of protein half-lives in non-dividing cells using pulsed stable isotope labeling by amino acids in cell culture (pSILAC) in combination with mass spectrometry. pSILAC involves metabolic labeling of cells with stable heavy isotope-containing versions of amino acids. Coupled with modern mass spectrometry approaches, pSILAC enables the measurement of protein turnover of hundreds or thousands of proteins in complex mixtures. After metabolic labeling, the turnover dynamics of proteins can be determined based on the relative enrichment of heavy isotopes in peptides detected by mass spectrometry. In this protocol, a workflow is described for the generation of senescent fibroblast cultures and similarly arrested quiescent fibroblasts, as well as a simplified, single-time point pSILAC labeling time-course that maximizes coverage of anticipated protein turnover rates. Further, a pipeline is presented for the analysis of pSILAC mass spectrometry data and user-friendly calculation of protein degradation rates using spreadsheets. The application of this protocol can be extended beyond senescent cells to any non-dividing cultured cells such as neurons.

Measurement of Protein Turnover Rates in Senescent and Non-Dividing Cultured Cells with Metabolic Labeling and Mass Spectrometry.

Mounting evidence has shown that the accumulation of senescent cells in the central nervous system contributes to neurodegenerative disorders such as Alzheimer's and Parkinson's diseases. Cellular senescence is a state of permanent cell cycle arrest that typically occurs in response to exposure to sub-lethal stresses. However, like other non-dividing cells, senescent cells remain metabolically active and carry out many functions that require unique transcriptional and translational demands and widespread changes in the intracellular and secreted proteomes. Understanding how protein synthesis and decay rates change during senescence can illuminate the underlying mechanisms of cellular senescence and find potential therapeutic avenues for diseases exacerbated by senescent cells. This paper describes a method for proteome-scale evaluation of protein half-lives in non-dividing cells using pulsed stable isotope labeling by amino acids in cell culture (pSILAC) in combination with mass spectrometry. pSILAC involves metabolic labeling of cells with stable heavy isotope-containing versions of amino acids. Coupled with modern mass spectrometry approaches, pSILAC enables the measurement of protein turnover of hundreds or thousands of proteins in complex mixtures. After metabolic labeling, the turnover dynamics of proteins can be determined based on the relative enrichment of heavy isotopes in peptides detected by mass spectrometry. In this protocol, a workflow is described for the generation of senescent fibroblast cultures and similarly arrested quiescent fibroblasts, as well as a simplified, single-time point pSILAC labeling time-course that maximizes coverage of anticipated protein turnover rates. Further, a pipeline is presented for the analysis of pSILAC mass spectrometry data and user-friendly calculation of protein degradation rates using spreadsheets. The application of this protocol can be extended beyond senescent cells to any non-dividing cultured cells such as neurons.

Expanded CUG Repeat RNA Induces Premature Senescence in Myotonic Dystrophy Model Cells.

Myotonic dystrophy type 1 (DM1) is a dominantly inherited disorder due to a toxic gain of function of RNA transcripts containing expanded CUG repeats (CUGexp). Patients with DM1 present with multisystemic symptoms, such as muscle wasting, cognitive impairment, cataract, frontal baldness, and endocrine defects, which resemble accelerated aging. Although the involvement of cellular senescence, a critical component of aging, was suggested in studies of DM1 patient-derived cells, the detailed mechanism of cellular senescence caused by CUGexp RNA remains unelucidated. Here, we developed a DM1 cell model that conditionally expressed CUGexp RNA in human primary cells so that we could perform a detailed assessment that eliminated the variability in primary cells from different origins. Our DM1 model cells demonstrated that CUGexp RNA expression induced cellular senescence by a telomere-independent mechanism. Furthermore, the toxic RNA expression caused mitochondrial dysfunction, excessive reactive oxygen species production, and DNA damage and response, resulting in the senescence-associated increase of cell cycle inhibitors p21 and p16 and secreted mediators insulin-like growth factor binding protein 3 (IGFBP3) and plasminogen activator inhibitor-1 (PAI-1). This study provides unequivocal evidence of the induction of premature senescence by CUGexp RNA in our DM1 model cells.

Molecular analysis of primary testicular germ cell tumor and matched metastatic teratomas.

425 Background: Metastastic teratoma (MT) is a unique germ cell tumor (GCT) subhistology characterized by resistance to platinum-based chemotherapy. Metastatic teratoma requires complete surgical excision, usually via retroperitoneal lymph node dissection (RPLND), following chemotherapy as a part of multidisciplinary GCT care. Molecular characterization of post-chemotherapy metastatic teratoma along with companion pre-chemotherapy testicular primary tumors could inform 1) the origin and differentiation site of metastatic teratomas, 2) mechanisms of platinum-resistance, 3) novel therapeutic options for patients with unresectable teratomas. Methods: We performed integrated molecular analysis for 16 primary germ cell tumors and 18 metastatic teratomas, 11 were matched tumor/metastasis pairs. All teratomas in our cohort were collected after induction platinum-based chemotherapy. In addition to SNV analysis, we conducted a chromosomal copy number gain and loss analysis for selected teratomas, matched primary tumors and primary teratomas from the TCGA. Results: Metastatic teratomas as well as their tumors of origin had low tumor mutation burden (0.65 and 0.47 accordingly). Amongst 583 SNVs detected in the study cohort, only two (KRAS p.Gly12Asp and KRAS p.Gly12Val) were previously described as oncogenic. Analysis of SNVs in proteins playing key roles in oncogenic signaling [1] showed that TP53 and Ras pathways were the most affected in metastatic teratomas. The majority of metastatic teratomas possess gain of 3p11.1 and loss of 10q26.3, 16p11.2, 19p13.2, 19q12 and 22q12.3 loci. Within 3p11.1 we did not identify any previously described oncodrivers. However, 5 chromosomal loci with lost heterozygosity contained 16 previously annotated tumor suppressor genes (15 protein coding and 1 microRNA, MIR199A1). Amongst those, GADD45GIP1 inhibition (growth arrest and DNA-damage-inducible, gamma interacting protein 1) is known for playing a role in cisplatin resistance through mechanism of cellular senescence [2]. Conclusions: Metastatic teratoma in our cohort is characterized by low tumor mutational burden, recurring copy number changes, and lack of recurring SNVs. Molecular insight of teratoma may inform disease biology and treatment.

Gerontology through the Eyes of 21st Century Toxicology.

Toxicants can cause cells to experience DNA damage, leading them to cellular senescence. Discovering mechanisms of cellular aging from birth to death will ease the process of understanding aging.

Senescence in chronic wounds and potential targeted therapies.

Chronic wounds (e.g. diabetic wounds, pressure wounds, vascular ulcers, etc.) do not usually heal in a timely and orderly manner but rather last for years and may lead to irreversible adverse events, resulting in a substantial financial burden for patients and society. Recently, a large amount of evidence has proven that cellular senescence has a crucial influence on chronic nonhealing wounds. As a defensive mechanism, cell senescence is a manner of cell-cycle arrest with increased secretory phenotype to resist death, preventing cells from stress-induced damage in cancer and noncancer diseases. A growing amount of research has advanced the perception of cell senescence in various chronic wounds and focuses on pathological and physiological processes and therapies targeting senescent cells. However, previous reviews have failed to sum up novel understandings of senescence in chronic wounds and emerging strategies targeting senescence. Herein, we discuss the characteristics and mechanisms of cellular senescence and the link between senescence and chronic wounds as well as some novel antisenescence strategies targeting other diseases that may be applied for chronic wounds.

Gerontological aspects of eye diseases

The global rate of aging is rapidly rising due to the increase in life expectancy, and the number of age-related diseases - including eye diseases - is increasing. The most common eye conditions affecting people over 50 years old are age-related macular degeneration, cataract, glaucoma and diabetic retinopathy. Timely and effective treatment of age-related eye diseases requires a deeper understanding of the cellular mechanisms of aging.

Multiple time-series expression trajectories imply dynamic functional changes during cellular senescence

Cellular senescence is a dynamic process driven by epigenetic and genetic changes. Although some transcriptomic signatures of senescent cells have been discovered, how these senescence-related signals change over time remains largely unclear. Here, we profiled the transcriptome dynamics of human dermal fibroblast (HDF) cells in successive stages of growth from proliferation to senescence. Based on time-series expression profile analysis, we discovered four trajectories (C1, C2, C3, C4) that are dynamically expressed as senescence progresses. While some genes were continuously up-regulated (C4) or down-regulated (C2) with aging, other genes did not change linearly with cell proliferation, but remained stable until entering the senescent state (C1, C3). Further analysis revealed that the four modes were enriched in different biological pathways, including regulation of cellular senescence. These findings provide a new perspective on understanding the dynamic regulatory mechanism of cellular senescence.

Analysis of Cell and Molecular Phenotypes of a Highly Replicated Longevity-Associated FOXO3 Variant in Older Adults

Aging demographics in the US, and other industrialized nations, are resulting in rapidly increasing health care costs from age-related diseases. New therapeutic interventions to extend healthspan in older adults requires understanding connections between basic aging biology and human longevity factors. Using clinical samples from the Kuakini Honolulu Heart Program (HHP) and their Offspring, we are examining potential links between molecular and cellular mechanisms of aging and the longevity associated FOXO3 genotype (carriage of SNP rs2802292 “G” allele). Telomere dynamics in leucocytes (LTL) have shown strong correlation with multiple lifestyle and health factors. We previously demonstrated a significant protective relation between FOXO3 longevity genotype and LTL in a cross-sectional study. Now we are assessing a longitudinal relation, at three time points over 20+ years, in older men. We are also exploring stem cell frequency and differentiation capacity in neurological and peripheral blood samples to assess FOXO3 genotype and human cell dynamics.

The Division of Aging Biology on Basic Research in Health Disparities

The core mission of the Division of Aging Biology is to explore the molecular and cellular mechanisms of aging. Work supported by the Division is best known for research using laboratory animals, but we have a less well-recognized program of research engaging human participants. With a goal expanding our presence in clinical research and the hope that we can have an impact on health disparities, this talk will provide an overview of how our grantees approach basic mechanistic questions of aging in human communities. In addition, a forward-looking but speculative presentation will be made on ways in which laboratory animals might be used to study health disparities from the perspective of hallmarks of aging.

Immune Surveillance of Senescent Cells

Cellular senescence involves a stable cell cycle arrest and a secretory program that modulates the tissue environment. In cancer, senescence acts as a potent barrier to tumorigenesis and, though many cancers evade senescence during the course of tumor evolution, ionizing radiation and conventional chemotherapy can, to varying degrees, induce senescence in tumor cells leading to potent anticancer effects. Conversely, the aberrant accumulation of senescent cells can reduce regenerative capacity and lead to tissue decline, contributing to tissue pathologies associated with age or the debilitating side-effects of cancer therapy. Our laboratory studies mechanisms of cellular senescence with the ultimate goal of developing strategies to modulate senescence for therapeutic benefit. We have focused on how senescent cells trigger immune surveillance to facilitate their own elimination or, when that fails, how synthetic immune cells (i.e. CAR T cells) can be directed to eliminate senescent cells. Recent advances in understanding senescent cell surveillance by the immune system will be discussed.

Enhancement of Bone-Forming Ability on Beta-Tricalcium Phosphate by Modulating Cellular Senescence Mechanisms Using Senolytics.

Various stresses latently induce cellular senescence that occasionally deteriorates the functioning of surrounding tissues. Nevertheless, little is known about the appearance and function of senescent cells, caused by the implantation of beta-tricalcium phosphate (β-TCP)—used widely in dentistry and orthopedics for treating bone diseases. In this study, two varying sizes of β-TCP granules (<300 μm and 300–500 μm) were implanted, and using histological and immunofluorescent staining, appearances of senescent-like cells in critical-sized bone defects in the calvaria of Sprague Dawley rats were evaluated. Parallelly, bone formation in defects was investigated with or without the oral administration of senolytics (a cocktail of dasatinib and quercetin). A week after the implantation, the number of senescence-associated beta-galactosidase, p21-, p19-, and tartrate-resistant acid phosphatase-positive cells increased and then decreased upon administrating senolytics. This administration of senolytics also attenuated 4-hydroxy-2-nonenal staining, representing reactive oxygen species. Combining senolytic administration with β-TCP implantation significantly enhanced the bone formation in defects as revealed by micro-computed tomography analysis and hematoxylin-eosin staining. This study demonstrates that β-TCP granules latently induce senescent-like cells, and senolytic administration may improve the bone-forming ability of β-TCP by inhibiting senescence-associated mechanisms.

Abstract 12138: Cell Senescence Associated H3K9me3 Decline Sensitizes Aortic Valve Cell for Osteogenic Response

Introduction: Cell senescence has been identified as an impact etiological factor in cardiovascular diseases, as well as calcific aortic valve disease (CAVD) . In our previous experiment results, We found that a large number of senescent aortic valve interstitial cells (AVIC) accumulated in the calcific aortic valve tissues, especially around the calcification sites. But the role and mechanism of cellular senescence in the development of calcified aortic stenosis have not been clarified. We hypothesized valvular interstitial cell senescence sensitize interstitial cell for osteogenic response through enhancing cell senescence associated epigenetic modification. Methods and Results: Representative immunofluorescence results of the clinical samples show that p16INK4A positive cells in the calcific aortic valve expressed more osteogenic associated factors, such as Runx2 and BMP2. And RAS system hyperactivation seemed to be an impact association with aortic valve calcification. Then we found Angiotensin II (1μM, 72h) chronic irritation induces valve interstitial cell senescence associated secretion phenotype (SASP) and activates osteogenic response through ERK1/2 and NF-κB pathway. ChIP-qPCR results demonstrated H3K9Me3 modifications on the promoters of Runx2, ACTA2(also known as α-SMA), IL-6, IL-8, MCP-1 were significantly decreased in angiotensin II pretreated AVIC. Blockage of angiotensin II and ABT-263 pretreatment inhibited valvular interstitial cell to convert into osteoblast-like phenotype induced by Angiotensin II, as well as attenuating senescence associated secretion phenotype factors yield. Blockage of angiotensin II receptor and p16 INK4A knockdown contributed to recover H3K9me3 modification on the promoters of those gene in angiotensin II pretreated AVIC through attenuating angiotensin II-induced ubiquitination degradation of SUV39H1. Conclusion: p16 INK4A mediated H3K9me3 decline sensitizes aortic valvular interstitial cell for osteogenic response, which impacts on aortic valve homeostasis and aortic valve calcification. Taken together, p16 INK4A positive senescent cells would be the potential target on prevention and treatment of calcific aortic valve disease.