Regulation of senescence traits by MAPKs

Insulin Sensitivity Controls Activity of Pathogenic CD4+ T Cells in Rheumatoid Arthritis

Hyperinsulinemia connects obesity, and a poor lipid profile, with type 2 diabetes (T2D). Here, we investigated consequences of insulin exposure for T cell function in the canonical autoimmunity of rheumatoid arthritis (RA). We observed that insulin levels correlated with the glycolytic index of CD4+ cells but suppressed transcription of insulin receptor substrates, which was inversely related to insulin sensitivity. This connection between insulin levels and the glycolytic index was not seen in CD4+ cells of healthy controls. Exposure of CD4+ cells to insulin induced a senescent state recognized by cell cycle arrest and DNA content enrichment measured by flow cytometry. It also resulted in accumulation of DNA damage marker γH2AX. Insulin suppressed IFNγ production and induced the senescence-associated secretome in CD4+ cell cultures and in patients with hyperinsulinemia. Inhibition of JAK-STAT signaling (JAKi) improved insulin signaling, which activated the glycolytic index and facilitated senescence in CD4+ cell cultures. Treatment with JAKi was associated with an abundance of naïve and recent thymic emigrant T cells in the circulation of RA patients. Thus, we concluded that insulin exerts immunosuppressive ability by inducing senescence and inhibiting IFNγ production in CD4+ cells. JAKi promotes insulin effects and supports elimination of the pathogenic CD4+ cell in RA patients.

A select thiosemicarbazone copper(II) complex induces apoptosis in gastric cancer and targets cancer stem cells reducing pluripotency markers

Copper(II)-based complexes are promising candidates as anti-cancer agents due to their ability to target cancer cells. Here we describe the synthesis and characterization of two copper(II) thiosemicarbazone complexes with the ligands 4-(dimethylamino)benzaldehyde N4-methylthiosemicarbazone (HL1) and 4-(dimethylamino)benzaldehyde N4-(4-(dimethylamino)phenylthiosemicarbazone (HL2) and general formula [Cu(L)2]. The complexes show stability in aqueous solution with 1 % of DMSO that allows to stablish its solution profile in biological buffers. Compound [Cu(L1)₂] lipophilicity was lower than [Cu(L2)₂], however, its solubility in biological buffer was not only better but also its DLS and ζ-potential data. In vitro studies demonstrate a higher cytotoxic effect of [Cu(L1)₂] on gastric cancer cells. The proposed mechanism of action consists in the generation of free radicals that induce DNA lesions, oxidative stress and ultimately autophagy deregulation and apoptosis. Additionally, [Cu(L1)₂] is equally active on gastric cancer stem cells and tumor cells resistant to cisplatin. More importantly, stem cells treated with [Cu(L1)₂] show a downregulation of pluripotency markers such as TWIST, NANOG and OCT4. Overall, our results with [Cu(L1)₂] prompt a significant advancement in the development of rational-designed pharmaceuticals for combating cancer.

Senescence and Stress Signaling Pathways in Corneal Cells After Nitrogen Mustard Injury

Mustard gas keratopathy (MGK), a complication of exposure to sulfur mustard, is a blinding ocular surface disease involving key cellular pathways, including apoptosis, oxidative stress, and inflammation. Recent studies indicate that cellular senescence contributes to the pathophysiology of mustard gas toxicity. This study aimed to assess senescence and stress-related pathways-particularly mitogen-activated protein kinase (MAPK) signaling-in nitrogen mustard (NM)-induced corneal injury. In vitro, primary human corneal epithelial (P-HCECs), primary human corneal mesenchymal stromal cells (hcMSCs), and human corneal-limbal epithelial cell (HCLE) lines were exposed to varying concentrations of NM. The results demonstrated a dose-dependent increase in cellular senescence, characterized by reduced Ki67 expression, elevated p16, and p21 mRNA levels, as well as activation of the MAPK pathway activation. Treatment with a selective p38-MAPK inhibitor significantly reduced senescence markers and improved cell proliferation following exposure to NM. Overall, these studies indicate that NM exposure triggers cellular senescence and stress-related MAPK signaling, while p38-MAPK inhibition mitigates these effects, suggesting a potential therapeutic strategy.

Investigating the role of nucleoside reverse transcriptase inhibitors in modulating lipotoxicity: Effects on lipid dynamics stress pathways, and insulin resistance on the function of dopaminergic neurons

Despite decades of advancements in HIV treatment, the persistence of viral reservoirs necessitates lifelong therapy, complicating efforts to fully control the infection. Nucleoside reverse transcriptase inhibitors (NRTIs) remain a cornerstone of HIV treatment, but long-term use is associated with side effects, including lipid metabolism disruption and neurocognitive disorders. There is a gap in understanding the safety of antiretrovirals and their impact on lipid toxicity in the central nervous system. To address this issue, our study investigated the impact of NRTIs, specifically lamivudine and zidovudine, on lipid metabolism and insulin resistance in the SH-SY5Y dopaminergic neuronal cell line. We also compared these effects to those induced by two free fatty acids, palmitic and docosahexaenoic acids. We measured mitochondrial superoxide levels, fatty acid binding proteins 4 and 5, and overall lipid content. Additionally, we assessed insulin resistance by analyzing the phosphorylation of mitogen-activated protein kinases and phosphoinositide 3-kinase, as well as the concentrations of insulin receptor substrate 1 and insulin receptor. The results demonstrated that NRTIs led to reduced fatty acid binding protein 4 levels and lipid content, similar to the effects observed with fatty acids. Moreover, lamivudine and zidovudine increased mitochondrial superoxide levels. Lamivudine also amplified the phosphorylation level of ERK. These findings suggest that NRTIs may contribute to lipotoxicity in dopaminergic neurons, warranting further investigation into their long-term effects on the central nervous system.

The syntaxin-binding protein STXBP5 regulates progerin expression

Hutchinson-Gilfor progeria syndrome (HGPS) is caused by a mutation in Lamin A resulting in the production of a protein called progerin. The accumulation of progerin induces inflammation, cellular senescence and activation of the P53 pathway. In this study, through public dataset analysis, we identified Syntaxin Binding Protein 5 (STXBP5) as an influencing factor of progerin expression. STXBP5 overexpression accelerated the onset of senescence, while STXBP5 deletion suppressed progerin expression, delayed senility, and decreased the expression of senescence-related factors. STXBP5 and progerin have synergistic effects and a protein-protein interaction. Through bioinformatics analysis, we found that STXBP5 affects ageing-related signalling pathways such as the mitogen-activated protein kinase (MAPK) pathway, the hippo pathway and the interleukin 17 (IL17) signalling pathway in progerin-expressing cells. In addition, STXBP5 overexpression induced changes in transposable elements (TEs), such as the human endogenous retrovirus H internal coding sequence (HERVH-int) changes. Our protein coimmunoprecipitation (Co-IP) results indicated that STXBP5 bound directly to progerin. Therefore, decreasing STXBP5 expression is a potential new therapeutic strategy for treating ageing-related phenotypes in patients with HGPS.

The Neolignan Honokiol and Its Synthetic Derivative Honokiol Hexafluoro Reduce Neuroinflammation and Cellular Senescence in Microglia Cells

Microglia-mediated neuroinflammation has been linked to neurodegenerative disorders. Inflammation and aging contribute to microglial senescence. Microglial senescence promotes the development of neurodegenerative disorders, including Alzheimer's disease (AD). In this study, we investigated the anti-neuroinflammatory and anti-senescence activity of Honokiol (HNK), a polyphenolic neolignane from Magnolia officinalis Rehder & E.H Wilson, in comparison with its synthetic analogue Honokiol Hexafluoro (CH). HNK reduced the pro-inflammatory cell morphology of LPS-stimulated BV2 microglia cells and increased the expression of the anti-inflammatory cytokine IL-10 with an efficacy comparable to CH. HNK and CH were also able to attenuate the alterations in cell morphology associated with cellular senescence in BV2 cells intermittently stimulated with LPS and significantly reduce the activity and expression of the senescence marker ß-galactosidase and the expression of p21 and pERK1/2. The treatments reduced the expression of senescence-associated secretory phenotype (SASP) factors IL-1ß and NF-kB, decreased ROS production, and abolished H2AX over phosphorylation (γ-H2AX) and acetylated H3 overexpression. Senescent microglia cells showed an increased expression of the Notch ligand Jagged1 that was reduced by HNK and CH with a comparable efficacy to the Notch inhibitor DAPT. Overall, our data illustrate a protective activity of HNK and CH on neuroinflammation and cellular senescence in microglia cells involving a Notch-signaling-mediated mechanism and suggesting a potential therapeutic contribution in aging-related neurodegenerative diseases.

Losmapimod ameliorates doxorubicin-induced cardiotoxicity through attenuating senescence and inflammatory pathways

Irreversible cardiotoxicity limits the clinical application of doxorubicin (DOX). DOX-induced cardiotoxicity has been associated with induction of senescence and activation of the p38 MAPK pathway. Losmapimod (LOSM), an orally active p38 MAPK inhibitor, is an anti-inflammatory agent with cardioprotective effects. Nevertheless, the effect of LOSM against DOX-induced cardiotoxicity has not been reported. In this study, we determined the effects of LOSM on DOX-induced chronic cardiotoxicity in C57BL/6 N mice. Five-week-old C57BL/6 N mice were fed diet containing LOSM (estimated daily intake 12 mg/kg/day) or a control diet for four days. Thereafter, mice were randomized to receive six weekly intraperitoneal injections of either DOX (4 mg/kg) or saline. Three days after the last injection, cardiac function was assessed by trans-thoracic echocardiography. Activation of p38, JNK, and ERK1/2 MAPKs were assessed by immunoblotting in the heart and liver. Gene expressions of senescence, inflammatory, oxidative stress, and mitochondrial function markers were quantified using real-time PCR and serum inflammatory markers were assessed by Luminex. Our results demonstrated that LOSM attenuated p38 MAPK activation, ameliorated DOX-induced cardiac dysfunction, and abrogated DOX-induced expression of the senescence marker p21Cip1. Additionally, LOSM demonstrated anti-inflammatory effects, with reduced cardiac Il-1α and Il-6 gene expression in DOX-treated mice. Systemic inflammation, assessed by serum cytokine levels, showed decreased IL-6 and CXCL1 in both DOX-treated mice and mice on LOSM diet. LOSM significantly increased mitofusin2 gene expression, which may enhance mitochondrial fusion. These findings underscore the potential therapeutic efficacy of p38 MAPK inhibition, exemplified by LOSM, in ameliorating DOX-induced cardiotoxicity, senescence, and inflammation.

Ovarian microenvironment: challenges and opportunities in protecting against chemotherapy-associated ovarian damage

BACKGROUND

Chemotherapy-associated ovarian damage (CAOD) is one of the most feared short- and long-term side effects of anticancer treatment in premenopausal women. Accumulating detailed data show that different chemotherapy regimens can lead to disturbance of ovarian hormone levels, reduced or lost fertility, and an increased risk of early menopause. Previous studies have often focused on the direct effects of chemotherapeutic drugs on ovarian follicles, such as direct DNA damage-mediated apoptotic death and primordial follicle burnout. Emerging evidence has revealed an imbalance in the ovarian microenvironment during chemotherapy. The ovarian microenvironment provides nutritional support and transportation of signals that stimulate the growth and development of follicles, ovulation, and corpus luteum formation. The close interaction between the ovarian microenvironment and follicles can determine ovarian function. Therefore, designing novel and precise strategies to manipulate the ovarian microenvironment may be a new strategy to protect ovarian function during chemotherapy.

OBJECTIVE AND RATIONALE

This review details the changes that occur in the ovarian microenvironment during chemotherapy and emphasizes the importance of developing new therapeutics that protect ovarian function by targeting the ovarian microenvironment during chemotherapy.

SEARCH METHODS

A comprehensive review of the literature was performed by searching PubMed up to April 2024. Search terms included 'ovarian microenvironment' (ovarian extracellular matrix, ovarian stromal cells, ovarian interstitial, ovarian blood vessels, ovarian lymphatic vessels, ovarian macrophages, ovarian lymphocytes, ovarian immune cytokines, ovarian oxidative stress, ovarian reactive oxygen species, ovarian senescence cells, ovarian senescence-associated secretory phenotypes, ovarian oogonial stem cells, ovarian stem cells), terms related to ovarian function (reproductive health, fertility, infertility, fecundity, ovarian reserve, ovarian function, menopause, decreased ovarian reserve, premature ovarian insufficiency/failure), and terms related to chemotherapy (cyclophosphamide, lfosfamide, chlormethine, chlorambucil, busulfan, melphalan, procarbazine, cisplatin, doxorubicin, carboplatin, taxane, paclitaxel, docetaxel, 5-fluorouraci, vincristine, methotrexate, dactinomycin, bleomycin, mercaptopurine).

OUTCOMES

The ovarian microenvironment shows great changes during chemotherapy, inducing extracellular matrix deposition and stromal fibrosis, angiogenesis disorders, immune microenvironment disturbance, oxidative stress imbalances, ovarian stem cell exhaustion, and cell senescence, thereby lowering the quantity and quality of ovarian follicles. Several methods targeting the ovarian microenvironment have been adopted to prevent and treat CAOD, such as stem cell therapy and the use of free radical scavengers, senolytherapies, immunomodulators, and proangiogenic factors.

WIDER IMPLICATIONS

Ovarian function is determined by its 'seeds' (follicles) and 'soil' (ovarian microenvironment). The ovarian microenvironment has been reported to play a vital role in CAOD and targeting the ovarian microenvironment may present potential therapeutic approaches for CAOD. However, the relation between the ovarian microenvironment, its regulatory networks, and CAOD needs to be further studied. A better understanding of these issues could be helpful in explaining the pathogenesis of CAOD and creating innovative strategies for counteracting the effects exerted on ovarian function. Our aim is that this narrative review of CAOD will stimulate more research in this important field.

REGISTRATION NUMBER

Not applicable.

10-hydroxy-2-decenoic acid prevents osteoarthritis by targeting aspartyl β hydroxylase and inhibiting chondrocyte senescence in male mice preclinically

Osteoarthritis is a degenerative joint disease with joint pain as the main symptom, caused by fibrosis and loss of articular cartilage. Due to the complexity and heterogeneity of osteoarthritis, there is a lack of effective individualized disease-modifying osteoarthritis drugs in clinical practice. Chondrocyte senescence is reported to participate in occurrence and progression of osteoarthritis. Here we show that small molecule 10-hydroxy-2-decenoic acid suppresses cartilage degeneration and relieves pain in the chondrocytes, cartilage explants from osteoarthritis patients, surgery-induced medial meniscus destabilization or naturally aged male mice. We further confirm that 10-hydroxy-2-decenoic acid exerts a protective effect by targeting the glycosylation site in the Asp_Arg_Hydrox domain of aspartyl β-hydroxylase. Mechanistically, 10-hydroxy-2-decenoic acid alleviate cellular senescence through the ERK/p53/p21 and GSK3β/p16 pathways in the chondrocytes. Our study uncovers that 10-hydroxy-2-decenoic acid modulate cartilage metabolism by targeting aspartyl β-hydroxylase to inhibit chondrocyte senescence in osteoarthritis. 10-hydroxy-2-decenoic acid may be a promising therapeutic drug against osteoarthritis.

Oxidative stress-mediated deleterious effects of hypoxia in the brackish water flea Diaphanosoma celebensis

In this study, we investigated the acute toxicity, in vivo effects, oxidative stress, and gene expression changes caused by hypoxia on the brackish water flea Diaphanosoma celebensis. The no-observed-effect concentration (NOEC) of 48 h of hypoxia exposure was found to be 2 mg/L O2. Chronic exposure to NOEC caused a significant decline in lifespan but had no effect on total fecundity. The induction of reactive oxygen species increased in a time-dependent manner over 48 h, whereas the content of antioxidant enzymes (superoxide dismutase and catalase) decreased. The transcription and translation levels were modulated by hypoxia exposure. In particular, a significant increase in hemoglobin level was followed by up-regulation of hypoxia-inducible factor 1α gene expression and activation of the mitogen-activated protein kinase pathway. In conclusion, our findings provide a better understanding of the molecular mechanism of the adverse effects of hypoxia in brackish water zooplankton.

Circulating microRNA profile of long-lived Okinawans identifies novel potential targets for optimizing lifespan and health span

Nonagenarians and centenarians serve as successful examples of aging and extended longevity, showcasing robust regulation of biological mechanisms and homeostasis. Given that human longevity is a complex field of study that navigates molecular and biological mechanisms influencing aging, we hypothesized that microRNAs, a class of small noncoding RNAs implicated in regulating gene expression at the post-transcriptional level, are differentially regulated in the circulatory system of young, middle-aged, and nonagenarian individuals. We sequenced circulating microRNAs in Okinawan males and females <40, 50-80, and >90 years of age accounting for FOXO3 genetic variations of single nucleotide polymorphism (SNP) rs2802292 (TT - common vs. GT - longevity) and validated the findings through RT-qPCR. We report five microRNAs exclusively upregulated in both male and female nonagenarians with the longevity genotype, play predictive functional roles in TGF-β, FoxO, AMPK, Pi3K-Akt, and MAPK signaling pathways. Our findings suggest that these microRNAs upregulated in nonagenarians may provide novel insight into enhanced lifespan and health span. This discovery warrants further exploration into their roles in human aging and longevity.

Depletion of Ppp6c in hematopoietic and vascular endothelial cells causes embryonic lethality and decreased hematopoietic potential

Protein phosphatase 6 (PP6) is a serine/threonine (Ser/Thr) protein phosphatase, and its catalytic subunit is Ppp6c. PP6 forms the PP2A subfamily with PP2A and PP4. The diverse phenotypes observed following small interfering RNA (siRNA)-based knockdown of Ppp6c in cultured mammalian cells suggest that PP6 plays roles in cell growth and DNA repair. There is also evidence that PP6 regulates nuclear factor kappa B (NF-κB) signaling and mitogen-activated protein kinases and inactivates transforming growth factor-β-activated kinase 1 (TAK1). Loss of Ppp6c causes several abnormalities, including those of T cell and regulatory T cell function, neurogenesis, oogenesis, and spermatogenesis. PP2A has been reported to play an important role in erythropoiesis. However, the roles of PP6 in other hematopoietic cells have not been investigated. We generated Ppp6cfl/fl;Tie2-Cre (Ppp6cTKO) mice, in which Ppp6c was specifically deleted in hematopoietic and vascular endothelial cells. Ppp6cTKO mice displayed embryonic lethality. Ppp6c deficiency increased the number of dead cells and decreased the percentages of erythroid and monocytic cells during fetal hematopoiesis. By contrast, the number of Lin-Sca-1+c-Kit+ cells, which give rise to all hematopoietic cells, was slightly increased, but their colony-forming cell activity was markedly decreased. Ppp6c deficiency also increased phosphorylation of extracellular signal-regulated kinase 1/2 and c-Jun amino (N)-terminal kinase in fetal liver hematopoietic cells.

Sprouty1 is a broad mediator of cellular senescence

Genes of the Sprouty family (Spry1-4) restrain signaling by certain receptor tyrosine kinases. Consequently, these genes participate in several developmental processes and function as tumor suppressors in adult life. Despite these important roles, the biology of this family of genes still remains obscure. Here we show that Sprouty proteins are general mediators of cellular senescence. Induction of cellular senescence by several triggers in vitro correlates with upregulation of Sprouty protein levels. More importantly, overexpression of Sprouty genes is sufficient to cause premature cellular senescence, via a conserved N-terminal tyrosine (Tyrosine 53 of Sprouty1). Accordingly, fibroblasts from knockin animals lacking that tyrosine escape replicative senescence. In vivo, heterozygous knockin mice display delayed induction of cellular senescence during cutaneous wound healing and upon chemotherapy-induced cellular senescence. Unlike other functions of this family of genes, induction of cellular senescence appears to be independent of activation of the ERK1/2 pathway. Instead, we show that Sprouty proteins induce cellular senescence upstream of the p38 pathway in these in vitro and in vivo paradigms.

Tobacco smoke condensate-induced senescence in endothelial cells was ameliorated by colchicine treatment via suppression of NF-κB and MAPKs P38 and ERK pathways activation

Smoking is the major cause of cardiovascular diseases and cancer. It induces oxidative stress, leading to DNA damage and cellular senescence. Senescent cells increase the expression and release of pro-inflammatory molecules and matrix metalloproteinase, which are known to play a vital role in the initiation and progression of cardiovascular diseases and metastasis in cancer. The current study investigated the smoking induced cellular senescence and employed colchicine that blocked senescence in endothelial cells exposed to tobacco smoke condensate. Colchicine prevented oxidative stress and DNA damage in tobacco smoke-condensate-treated endothelial cells. Colchicin reduced β-gal activity, improved Lamin B1, and attenuated cell growth arrest markers P21 and P53. Colchicine also ameliorated the expression of SASP factors and inhibited the activation of NF-kB and MAPKs P38 and ERK. In summary, colchicine inhibited tobacco smoke condensate-induced senescence in endothelial cells by blocking the activation of NF-kB and MAPKs P38 and ERK.

Cellular senescence in chronic lung diseases from newborns to the elderly: An update literature review

The role of cellular senescence in age-related diseases has been fully recognized. In various age-related-chronic lung diseases, the function of alveolar epithelial cells (AECs) is impaired and alveolar regeneration disorders, especially in bronchopulmonary dysplasia，pulmonary fibrosis (PF), chronic obstructive pulmonary disease (COPD), cancer, etc. Except for age-related-chronic lung diseases, an increasing number of studies are exploring the role of cellular senescence in developmental chronic lung diseases, which typically originate in childhood and even in the neonatal period. This review provides an overview of cellular senescence and lung diseases from newborns to the elderly, attempting to draw attention to the relationship between cellular senescence and developmental lung diseases.

Senolytic therapeutics: An emerging treatment modality for osteoarthritis

Osteoarthritis (OA), a chronic joint disease affecting millions of people aged over 65 years, is the main musculoskeletal cause of diminished joint mobility in the elderly. It is characterized by lingering pain and increasing deterioration of articular cartilage. Aging and accumulation of senescent cells (SCs) in the joints are frequently associated with OA. Apoptosis resistance; irreversible cell cycle arrest; increased p16INK4a expression, secretion of senescence-associated secretory phenotype factors, senescence-associated β-galactosidase levels, secretion of extracellular vesicles, and levels of reactive oxygen and reactive nitrogen species; and mitochondrial dysregulation are some common changes in cellular senescence in joint tissues. Development of OA correlates with an increase in the density of SCs in joint tissues. Senescence-associated secretory phenotype has been linked to OA and cartilage breakdown. Senolytics and therapeutic pharmaceuticals are being focused upon for OA management. SCs can be selectively eliminated or killed by senolytics to halt the pathogenesis and progression of OA. Comprehensive understanding of how aging affects joint dysfunction will benefit OA patients. Here, we discuss age-related mechanisms associated with OA pathogenesis and senolytics as an emerging modality in the management of age-related SCs and pathogenesis of OA in preclinical and clinical studies.

Mitochondrial injury induced by a Salmonella genotoxin triggers the proinflammatory senescence-associated secretory phenotype

Bacterial genotoxins damage host cells by targeting their chromosomal DNA. In the present study, we demonstrate that a genotoxin of Salmonella Typhi, typhoid toxin, triggers the senescence-associated secretory phenotype (SASP) by damaging mitochondrial DNA. The actions of typhoid toxin disrupt mitochondrial DNA integrity, leading to mitochondrial dysfunction and disturbance of redox homeostasis. Consequently, it facilitates the release of damaged mitochondrial DNA into the cytosol, activating type I interferon via the cGAS-STING pathway. We also reveal that the GCN2-mediated integrated stress response plays a role in the upregulation of inflammatory components depending on the STING signaling axis. These SASP factors can propagate the senescence effect on T cells, leading to senescence in these cells. These findings provide insights into how a bacterial genotoxin targets mitochondria to trigger a proinflammatory SASP, highlighting a potential therapeutic target for an anti-toxin intervention.

Platinum iodido drugs show potential anti-tumor activity, affecting cancer cell metabolism and inducing ROS and senescence in gastrointestinal cancer cells

Cisplatin-based chemotherapy has associated clinical disadvantages, such as high toxicity and resistance. Thus, the development of new antitumor metallodrugs able to overcome different clinical barriers is a public healthcare priority. Here, we studied the mechanism of action of the isomers trans and cis-[PtI2(isopropylamine)2] (I5 and I6, respectively) against gastrointestinal cancer cells. We demonstrate that I5 and I6 modulate mitochondrial metabolism, decreasing OXPHOS activity and negatively affecting ATP-linked oxygen consumption rate. Consequently, I5 and I6 generated Reactive Oxygen Species (ROS), provoking oxidative damage and eventually the induction of senescence. Thus, herein we propose a loop with three interconnected processes modulated by these iodido agents: (i) mitochondrial dysfunction and metabolic disruptions; (ii) ROS generation and oxidative damage; and (iii) cellular senescence. Functionally, I5 reduces cancer cell clonogenicity and tumor growth in a pancreatic xenograft model without systemic toxicity, highlighting a potential anticancer complex that warrants additional pre-clinical studies.

Intervention treatment reducing cellular senescence inhibits tubulointerstitial fibrosis in diabetic mice following acute kidney injury

Senescence of kidney tubules leads to tubulointerstitial fibrosis (TIF). Proximal tubular epithelial cells undergo stress-induced senescence during diabetes and episodes of acute kidney injury (AKI), and combining these injuries promotes the progression of diabetic kidney disease (DKD). Since TIF is crucial to progression of DKD, we examined the therapeutic potential of targeting senescence with a senolytic drug (HSP90 inhibitor) and/or a senostatic drug (ASK1 inhibitor) in a model of TIF in which AKI is superimposed on diabetes. After 8 weeks of streptozotocin-induced diabetes, mice underwent bilateral clamping of renal pedicles to induce mild AKI, followed by 28 days of reperfusion. Groups of mice (n=10-12) received either vehicle, HSP90 inhibitor (alvespimycin), ASK1 inhibitor (GS-444217), or both treatments. Vehicle-treated mice displayed tubular injury at day 3 and extensive tubular cell senescence at day 10, which remained unresolved at day 28. Markers of senescence (Cdkn1a and Cdkn2a), inflammation (Cd68, Tnf, and Ccl2), and TIF (Col1a1, Col4a3, α-Sma/Acta2, and Tgfb1) were elevated at day 28, coinciding with renal function impairment. Treatment with alvespimycin alone reduced kidney senescence and levels of Col1a1, Acta2, Tgfb1, and Cd68; however, further treatment with GS-444217 also reduced Col4a3, Tnf, Ccl2, and renal function impairment. Senolytic therapy can inhibit TIF during DKD, but its effectiveness can be improved by follow-up treatment with a senostatic inhibitor, which has important implications for treating progressive DKD.

Hexavalent Chromium Induces Neurotoxicity by Triggering Mitochondrial Dysfunction and ROS-Mediated Signals

Hexavalent chromium (Cr (VI)), one of the most detrimental pollutants, has been ubiquitously present in the environment and causes serious toxicity to humans, such as hepatotoxicity, nephrotoxicity, pulmonary toxicity, and cardiotoxicity. However, Cr (VI)-induced neurotoxicity in primary neuron level has not been well explored yet. Herein, potassium dichromate (K2Cr2O7) was employed to examine the neurotoxicity of Cr (VI) in rat primary hippocampal neurons. MTT test was used to examine the neural viability. Mitochondrial dysfunction was assessed by the JC-1 probe and Mito-Tracker probe. DCFH-DA and Mito-SOX Red were utilized to evaluate the oxidative status. Bcl-2 family and MAPKs expression were investigated using Western blotting. The results demonstrated that Cr (VI) treatment dose- and time-dependently inhibited neural viability. Mechanism investigation found that Cr (VI) treatment causes mitochondrial dysfunction by affecting Bcl-2 family expression. Moreover, Cr (VI) treatment also induces intracellular reactive oxygen species (ROS) generation, DNA damage, and MAPKs activation in neurons. However, inhibition of ROS by glutathione (GSH) effectually balanced Bcl-2 family expression, attenuated DNA damage and the MAPKs activation, and eventually improved neural viability neurons. Collectively, these above results above suggest that Cr (VI) causes significant neurotoxicity by triggering mitochondrial dysfunction, ROS-mediated oxidative damage and MAKPs activation.

Asynchronous Pattern of MAPKs' Activity during Aging of Different Tissues and of Distinct Types of Skeletal Muscle

The MAPK p38α was proposed to be a prominent promoter of skeletal muscle aging. The skeletal muscle tissue is composed of various muscle types, and it is not known if p38α is associated with aging in all of them. It is also not known if p38α is associated with aging of other tissues. JNK and ERK were also proposed to be associated with aging of several tissues. Nevertheless, the pattern of p38α, JNK, and ERK activity during aging was not documented. Here, we documented the levels of phosphorylated/active p38α, Erk1/2, and JNKs in several organs as well as the soleus, tibialis anterior, quadriceps, gastrocnemius, and EDL muscles of 1-, 3-, 6-, 13-, 18-, and 24-month-old mice. We report that in most tissues and skeletal muscles, the MAPKs' activity does not change in the course of aging. In most tissues and muscles, p38α is in fact active at younger ages. The quadriceps and the lungs are exceptions, where p38α is significantly active only in mice 13 months old or older. Curiously, levels of active JNK and ERKs are also elevated in aged lungs and quadriceps. RNA-seq analysis of the quadriceps during aging revealed downregulation of proteins related to the extra-cellular matrix (ECM) and ERK signaling. A panel of mRNAs encoding cell cycle inhibitors and senescence-associated proteins, considered to be aging markers, was not found to be elevated. It seems that the pattern of MAPKs' activation in aging, as well as expression of known 'aging' components, are tissue- and muscle type-specific, supporting a notion that the process of aging is tissue- and even cell-specific.

Hesperetin activates CISD2 to attenuate senescence in human keratinocytes from an older person and rejuvenates naturally aged skin in mice

BACKGROUND

CDGSH iron-sulfur domain-containing protein 2 (CISD2), a pro-longevity gene, mediates healthspan in mammals. CISD2 is down-regulated during aging. Furthermore, a persistently high level of CISD2 promotes longevity and ameliorates an age-related skin phenotype in transgenic mice. Here we translate the genetic evidence into a pharmaceutical application using a potent CISD2 activator, hesperetin, which enhances CISD2 expression in HEK001 human keratinocytes from an older person. We also treated naturally aged mice in order to study the activator's anti-aging efficacy.

METHODS

We studied the biological effects of hesperetin on aging skin using, firstly, a cell-based platform, namely a HEK001 human keratinocyte cell line established from an older person. Secondly, we used a mouse model, namely old mice at 21-month old. In the latter case, we investigate the anti-aging efficacy of hesperetin on ultraviolet B (UVB)-induced photoaging and naturally aged skin. Furthermore, to identify the underlying mechanisms and potential biological pathways involved in this process we carried out transcriptomic analysis. Finally, CISD2 knockdown HEK001 keratinocytes and Cisd2 knockout mice were used to study the Cisd2-dependent effects of hesperetin on skin aging.

RESULTS

Four findings are pinpointed. Firstly, in human skin, CISD2 is mainly expressed in proliferating keratinocytes from the epidermal basal layer and, furthermore, CISD2 is down-regulated in the sun-exposed epidermis. Secondly, in HEK001 human keratinocytes from an older person, hesperetin enhances mitochondrial function and protects against reactive oxygen species-induced oxidative stress via increased CISD2 expression; this enhancement is CISD2-dependent. Additionally, hesperetin alleviates UVB-induced damage and suppresses matrix metalloproteinase-1 expression, the latter being a major indicator of UVB-induced damage in keratinocytes. Thirdly, transcriptomic analysis revealed that hesperetin modulates a panel of differentially expressed genes that are associated with mitochondrial function, redox homeostasis, keratinocyte function, and inflammation in order to attenuate senescence. Intriguingly, hesperetin activates two known longevity-associated regulators, namely FOXO3a and FOXM1, in order to suppress the senescence-associated secretory phenotype. Finally, in mouse skin, hesperetin enhances CISD2 expression to ameliorate UVB-induced photoaging and this occurs via a mechanism involving CISD2. Most strikingly, late-life treatment with hesperetin started at 21-month old and lasting for 5 months, is able to retard skin aging and rejuvenate naturally aged skin in mice.

CONCLUSIONS

Our results reveal that a pharmacological elevation of CISD2 expression at a late-life stage using hesperetin treatment is a feasible approach to effectively mitigating both intrinsic and extrinsic skin aging and that hesperetin could act as a functional food or as a skincare product for fighting skin aging.

Red Ginseng Attenuates the Hepatic Cellular Senescence in Aged Mice

Cellular senescence is defined as an irreversible cell cycle arrest accompanied by morphological and physiological alterations during aging. Red ginseng (RG), processed from fresh ginseng (Panax ginseng C.A. Meyer) with a one-time steaming and drying process, is a well-known beneficial herbal medicine showing antioxidant, anti-inflammatory, and anti-aging properties. The current study aimed to investigate the benefits of RG in alleviating hepatic cellular senescence and its adverse effects in 19-month-old aged mice. We applied two different intervention methods and durations to compare RG's effects in a time-dependent manner: (1) oral gavage injection for 4 weeks and (2) ad libitum intervention for 14 weeks. We observed that 4-week RG administration was exerted to maintain insulin homeostasis against developing age-associated insulin insensitivity and suppressed cellular senescence pathway in the liver and primary hepatocytes. Moreover, with remarkable improvement of insulin homeostasis, 14-week RG supplementation downregulated the activation of c-Jun N-terminal kinase (JNK) and its downstream transcriptional factor nuclear factor-κB (NF-κB) in aged mice. Lastly, RG treatment significantly reduced the senescence-associated β-galactosidase (SA-β-gal)-positive cells in primary hepatocytes and ionizing radiation (IR)-exposed mouse embryonic fibroblasts (MEFs). Taken together, we suggest that RG can be a promising candidate for a senolytic substance by preventing hepatic cellular senescence.

Remodeling of the Cardiac Extracellular Matrix Proteome During Chronological and Pathological Aging

Impaired extracellular matrix (ECM) remodeling is a hallmark of many chronic inflammatory disorders that can lead to cellular dysfunction, aging, and disease progression. The ECM of the aged heart and its effects on cardiac cells during chronological and pathological aging are poorly understood across species. For this purpose, we first used mass spectrometry-based proteomics to quantitatively characterize age-related remodeling of the left ventricle (LV) of mice and humans during chronological and pathological (Hutchinson-Gilford progeria syndrome (HGPS)) aging. Of the approximately 300 ECM and ECM-associated proteins quantified (named as Matrisome), we identified 13 proteins that were increased during aging, including lactadherin (MFGE8), collagen VI α6 (COL6A6), vitronectin (VTN) and immunoglobulin heavy constant mu (IGHM), whereas fibulin-5 (FBLN5) was decreased in most of the data sets analyzed. We show that lactadherin accumulates with age in large cardiac blood vessels and when immobilized, triggers phosphorylation of several phosphosites of GSK3B, MAPK isoforms 1, 3, and 14, and MTOR kinases in aortic endothelial cells (ECs). In addition, immobilized lactadherin increased the expression of pro-inflammatory markers associated with an aging phenotype. These results extend our knowledge of the LV proteome remodeling induced by chronological and pathological aging in different species (mouse and human). The lactadherin-triggered changes in the proteome and phosphoproteome of ECs suggest a straight link between ECM component remodeling and the aging process of ECs, which may provide an additional layer to prevent cardiac aging.

IGF2 deficiency promotes liver aging through mitochondrial dysfunction and upregulated CEBPB signaling in D-galactose-induced aging mice

BACKGROUND

Liver aging, marked by cellular senescence and low-grade inflammation, heightens susceptibility to chronic liver disease and worsens its prognosis. Insulin-like growth factor 2 (IGF2) has been implicated in numerous aging-related diseases. Nevertheless, its role and underlying molecular mechanisms in liver aging remain largely unexplored.

METHODS

The expression of IGF2 was examined in the liver of young (2-4 months), middle-aged (9-12 months), and old (24-26 months) C57BL/6 mice. In vivo, we used transgenic IGF2f/f; Alb-Cre mice and D-galactose-induced aging model to explore the role of IGF2 in liver aging. In vitro, we used specific short hairpin RNA against IGF2 to knock down IGF2 in AML12 cells. D-galactose and hydrogen peroxide treatment were used to induce AML12 cell senescence.

RESULTS

We observed a significant reduction of IGF2 levels in the livers of aged mice. Subsequently, we demonstrated that IGF2 deficiency promoted senescence phenotypes and senescence-associated secretory phenotypes (SASPs), both in vitro and in vivo aging models. Moreover, IGF2 deficiency impaired mitochondrial function, reducing mitochondrial respiratory capacity, mitochondrial membrane potential, and nicotinamide adenine dinucleotide (NAD)+/NADH ratio, increasing intracellular and mitochondrial reactive oxygen species levels, and disrupting mitochondrial membrane structure. Additionally, IGF2 deficiency markedly upregulated CCAAT/enhancer-binding protein beta (CEBPB). Notably, inhibiting CEBPB reversed the senescence phenotypes and reduced SASPs induced by IGF2 deficiency.

CONCLUSIONS

In summary, our findings strongly suggest that IGF2 deficiency promotes liver aging through mitochondrial dysfunction and upregulated CEBPB signaling. These results provide compelling evidence for considering IGF2 as a potential target for interventions aimed at slowing down the process of liver aging.

Colchicine prevents oxidative stress-induced endothelial cell senescence via blocking NF-κB and MAPKs: implications in vascular diseases

BACKGROUND

Smoking, alcohol abuse, and hypertension are - among others, potential risk factors for cardiovascular diseases. These risk factors generate oxidative stress and cause oxidative stress-induced DNA damage, resulting in cellular senescence and senescence-associated secretory phenotype (SASP). The SASP factors in feed-forward response exacerbate inflammation and cause tissue remodeling, resulting in atherosclerotic plaque formation and rupture.

RESULTS

Colchicine inhibited ROS generation and mitigated oxidative stress-induced DNA damage. It dampened oxidative stress-induced endothelial cell senescence and improved the expression of DNA repair protein KU80 and aging marker Lamin B1. The drug attenuated the expression of senescence marker P21 at mRNA and protein levels. The pathway analysis showed that colchicine inhibited NF-κB and MAPKs pathways and subdued mTOR activation. Colchicine also attenuated mRNA expression of interleukin (IL)-1β, IL-6, IL-8, MCP-1, ICAM-1, and E-selectin. Furthermore, colchicine reduced the mRNA and protein expression of matrix metalloproteinase (MMP-2).

CONCLUSION

In summary, colchicine blocked oxidative stress-induced senescence and SASP by inhibiting the activation of NF-κB and MAPKs pathways.

mTOR Inhibitor Rapalink-1 Prevents Ethanol-Induced Senescence in Endothelial Cells

The cardiovascular risk factors, including smoking, ethanol, and oxidative stress, can induce cellular senescence. The senescent cells increase the expression and release of pro-inflammatory molecules and matrix metalloproteinase (MMPs). These pro-inflammatory molecules and MMPs promote the infiltration and accumulation of inflammatory cells in the vascular tissue, exacerbating vascular tissue inflammation. MMPs damage vascular tissue by degenerating the extracellular matrix. Consequently, these cellular and molecular events promote the initiation and progression of cardiovascular diseases. We used Rapalink-1, an mTOR inhibitor, to block ethanol-induced senescence. Rapalink-1 inhibited oxidative-stress-induced DNA damage and senescence in endothelial cells exposed to ethanol. It attenuated the relative protein expression of senescence marker P21 and improved the relative protein expression of DNA repair protein KU70 and aging marker Lamin B1. It inhibited the activation of NF-κB, MAPKs (P38 and ERK), and mTOR pathway proteins (mTOR, 4EBP-1, and S6). Moreover, Rapalink-1 suppressed ethanol-induced mRNA expression of ICAM-1, E-selectin, MCP-1, IL-8, MMP-2, and TIMP-2. Rapalink-1 also reduced the relative protein expression of MMP-2. In summary, Rapalink-1 prevented senescence, inhibited pro-inflammatory pathway activation, and ameliorated pro-inflammatory molecule expression and MMP-2.

Understanding cellular senescence: pathways involved, therapeutics and longevity aiding

A normal somatic cell undergoes cycles of finite cellular divisions. The presence of surveillance checkpoints arrests cell division in response to stress inducers: oxidative stress from excess free radicals, oncogene-induced abnormalities, genotoxic stress, and telomere attrition. When facing such stress when undergoing these damages, there is a brief pause in the cell cycle to enable repair mechanisms. Also, the nature of stress determines whether the cell goes for repair or permanent arrest. As the cells experience transient or permanent stress, they subsequently choose the quiescence or senescence stage, respectively. Quiescence is an essential stage that allows the arrested/damaged cells to go through appropriate repair mechanisms and then revert to the mainstream cell cycle. However, senescent cells are irreversible and accumulate with age, resulting in inflammation and various age-related disorders. In this review, we focus on senescence-associated pathways and therapeutics understanding cellular senescence as a cascade that leads to aging, while discussing the recent details on the molecular pathways involved in regulating senescence and the benefits of therapeutic strategies against accumulated senescent cells and their secretions.

Dynamics of redox signaling in aging via autophagy, inflammation, and senescence

Review paper attempts to explain the dynamic aspects of redox signaling in aging through autophagy, inflammation, and senescence. It begins with ROS source in the cell, then states redox signaling in autophagy, and regulation of autophagy in aging. Next, we discuss inflammation and redox signaling with various pathways involved: NOX pathway, ROS production via TNF-α, IL-1β, xanthine oxidase pathway, COX pathway, and myeloperoxidase pathway. Also, we emphasize oxidative damage as an aging marker and the contribution of pathophysiological factors to aging. In senescence-associated secretory phenotypes, we link ROS with senescence, aging disorders. Relevant crosstalk between autophagy, inflammation, and senescence using a balanced ROS level might reduce age-related disorders. Transducing the context-dependent signal communication among these three processes at high spatiotemporal resolution demands other tools like multi-omics aging biomarkers, artificial intelligence, machine learning, and deep learning. The bewildering advancement of technology in the above areas might progress age-related disorders diagnostics with precision and accuracy.

Phase 2 Trial of Stereotactic Ablative Radiotherapy for Patients with Primary Renal Cancer

BACKGROUND

Most renal cell carcinomas (RCCs) are localized and managed by active surveillance, surgery, or minimally invasive techniques. Stereotactic ablative radiation (SAbR) may provide an innovative non-invasive alternative although prospective data are limited.

OBJECTIVE

To investigate whether SAbR is effective in the management of primary RCCs.

DESIGN, SETTING, AND PARTICIPANTS

Patients with biopsy-confirmed radiographically enlarging primary RCC (≤5 cm) were enrolled. SAbR was delivered in either three (12 Gy) or five (8 Gy) fractions.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

The primary endpoint was local control (LC) defined as a reduction in tumor growth rate (compared with a benchmark of 4 mm/yr on active surveillance) and pathologic evidence of tumor response at 1 yr. Secondary endpoints included LC by the Response Evaluation Criteria in Solid Tumors (RECIST 1.1), safety, and preservation of kidney function. Exploratory tumor cell-enriched spatial protein and gene expression analysis were conducted on pre- and post-treatment biopsy samples.

RESULTS AND LIMITATIONS

Target accrual was reached with the enrollment of 16 ethnically diverse patients. Radiographic LC at 1 yr was observed in 94% of patients (15/16; 95% confidence interval: 70, 100), and this was accompanied by pathologic evidence of tumor response (hyalinization, necrosis, and reduced tumor cellularity) in all patients. By RECIST, 100% of the sites remained without progression at 1 yr. The median pretreatment growth rate was 0.8 cm/yr (interquartile range [IQR]: 0.3, 1.4), and the median post-treatment growth rate was 0.0 cm/yr (IQR: -0.4, 0.1, p < 0.002). Tumor cell viability decreased from 4.6% to 0.7% at 1 yr (p = 0.004). With a median follow-up of 36 mo for censored patients, the disease control rate was 94%. SAbR was well tolerated with no grade ≥2 (acute or late) toxicities. The average glomerular filtration rate declined from a baseline of 65.6 to 55.4 ml/min at 1 yr (p = 0.003). Spatial protein and gene expression analyses were consistent with the induction of cellular senescence by radiation.

CONCLUSIONS

This clinical trial adds to the growing body of evidence suggesting that SAbR is effective for primary RCC supporting its evaluation in comparative phase 3 clinical trials.

PATIENT SUMMARY

In this clinical trial, we investigated a noninvasive treatment option of stereotactic radiation therapy for the treatment of primary kidney cancer and found that it was safe and effective.

Run, Ribosome, Run: From Compromised Translation to Human Health

Significance: Translation is an essential cellular process, and diverse signaling pathways have evolved to deal with problems arising during translation. Erroneous stalls and unresolved ribosome collisions are implicated in many pathologies, including neurodegeneration and metabolic dysregulation. Recent Advances: Many proteins involved in detection and clearance of stalled and collided ribosomes have been identified and studied in detail. Ribosome profiling techniques have revealed extensive and nonprogrammed ribosome stalling and leaky translation into the 3' untranslated regions of mRNAs. Impairment of protein synthesis has been linked to aging in yeast and mice. Critical Issues: Ribosomes act as sensors of cellular states, but the molecular mechanisms, as well as physiological relevance, remain understudied. Most of our current knowledge stems from work in yeast and simple multicellular organisms such as Caenorhabditis elegans, while we are only beginning to comprehend the role of ribosome surveillance in higher organisms. As an example, the ribotoxic stress response, a pathway responding to global translational stress, has been studied mostly in response to small translation inhibitors and ribotoxins, and has only recently been explored in physiological settings. This review focuses on ribosome-surveillance pathways and their importance for cell and tissue homeostasis upon naturally occurring insults such as oxidative stress, nutrient deprivation, and viral infections. Future Directions: A better insight into the physiological roles of ribosome-surveillance pathways and their crosstalk could lead to an improved understanding of human pathologies and aging. Antioxid. Redox Signal. 39, 336-350.

MAGI1 Prevents Senescence and Promotes the DNA Damage Response in ER+ Breast Cancer

MAGI1 acts as a tumor suppressor in estrogen receptor-positive (ER+) breast cancer (BC), and its loss correlates with a more aggressive phenotype. To identify the pathways and events affected by MAGI1 loss, we deleted the MAGI1 gene in the ER+ MCF7 BC cell line and performed RNA sequencing and functional experiments in vitro. Transcriptome analyses revealed gene sets and biological processes related to estrogen signaling, the cell cycle, and DNA damage responses affected by MAGI1 loss. Upon exposure to TNF-α/IFN-γ, MCF7 MAGI1 KO cells entered a deeper level of quiescence/senescence compared with MCF7 control cells and activated the AKT and MAPK signaling pathways. MCF7 MAGI1 KO cells exposed to ionizing radiations or cisplatin had reduced expression of DNA repair proteins and showed increased sensitivity towards PARP1 inhibition using olaparib. Treatment with PI3K and AKT inhibitors (alpelisib and MK-2206) restored the expression of DNA repair proteins and sensitized cells to fulvestrant. An analysis of human BC patients' transcriptomic data revealed that patients with low MAGI1 levels had a higher tumor mutational burden and homologous recombination deficiency. Moreover, MAGI1 expression levels negatively correlated with PI3K/AKT and MAPK signaling, which confirmed our in vitro observations. Pharmacological and genomic evidence indicate HDACs as regulators of MAGI1 expression. Our findings provide a new view on MAGI1 function in cancer and identify potential treatment options to improve the management of ER+ BC patients with low MAGI1 levels.

Prolactin Regulates Ovine Ovarian Granulosa Cell Apoptosis by Affecting the Expression of MAPK12 Gene

Prolactin (PRL) has been reported to influence reproductive performance and cell apoptosis. However, its mechanism remains unclear. Hence, in the present study, ovine ovarian granulosa cells (GCs) were used as a cell model to investigate the relationship between PRL concentration and GC apoptosis, as well as its possible mechanisms. We examined the relationship between serum PRL concentration and follicle counts in sexually mature ewes. GCs were isolated from adult ewes and treated with different concentrations of PRL, while 500 ng/mL PRL was selected as the high concentration of prolactin (HPC). Then, we applied the transcriptome sequencing (RNA-Seq) combined with a gene editing approach to explore the HPC contributing to cell apoptosis and steroid hormones. The apoptosis of GCs gradually increased at PRL concentrations above 20 ng/mL, while 500 ng/mL PRL significantly decreased the secretion of steroid hormones and the expression of L-PRLR and S-PRLR. The results indicated that PRL regulates GC development and steroid hormones mainly through the target gene MAPK12. The expression of MAPK12 was increased after knocked-down L-PRLR and S-PRLR, while it decreased after overexpressed L-PRLR and S-PRLR. Cell apoptosis was inhibited and the secretion of steroid hormones increased after interfering with MAPK12, while the overexpression of MAPK12 showed the opposite trend. Overall, the number of follicles gradually decreased with increasing PRL concentration. HPCs promoted apoptosis and inhibited steroid hormone secretion in GCs by upregulating MAPK12 through reducing L-PRLR and S-PRLR.

Cellular senescence in skin-related research: Targeted signaling pathways and naturally occurring therapeutic agents

Despite the growing interest by researchers into cellular senescence, a hallmark of cellular aging, its role in human skin remains equivocal. The skin is the largest and most accessible human organ, reacting to the external and internal environment. Hence, it is an organ of choice to investigate cellular senescence and to target root-cause aging processes using senolytic and senomorphic agents, including naturally occurring plant-based derivatives. This review presents different aspects of skin cellular senescence, from physiology to pathology and signaling pathways. Cellular senescence can have both beneficial and detrimental effects on the skin, indicating that both prosenescent and antisenescent therapies may be desirable, based on the context. Knowledge of molecular mechanisms involved in skin cellular senescence may provide meaningful insights for developing effective therapeutics for senescence-related skin disorders, such as wound healing and cosmetic skin aging changes.

Current concepts of microRNA-mediated regulatory mechanisms in human pulp tissue-derived stem cells: a snapshot in the regenerative dentistry

One of the most studied class of non-coding RNAs is microRNAs (miRNAs) which regulate more than 60% of human genes. A network of miRNA gene interactions participates in stem cell self-renewal, proliferation, migration, apoptosis, immunomodulation, and differentiation. Human pulp tissue-derived stem cells (PSCs) are an attractive source of dental mesenchymal stem cells (MSCs) which comprise human dental pulp stem cells (hDPSCs) obtained from the dental pulp of permanent teeth and stem cells isolated from exfoliated deciduous teeth (SHEDs) that would be a therapeutic opportunity in stomatognathic system reconstruction and repair of other damaged tissues. The regenerative capacity of hDPSCs and SHEDs is mediated by osteogenic, odontogenic, myogenic, neurogenic, angiogenic differentiation, and immunomodulatory function. Multi-lineage differentiation of PSCs can be induced or inhibited by the interaction of miRNAs with their target genes. Manipulating the expression of functional miRNAs in PSCs by mimicking miRNAs or inhibiting miRNAs emerged as a therapeutic tool in the clinical translation. However, the effectiveness and safety of miRNA-based therapeutics, besides higher stability, biocompatibility, less off-target effects, and immunologic reactions, have received particular attention. This review aimed to comprehensively overview the molecular mechanisms underlying miRNA-modified PSCs as a futuristic therapeutic option in regenerative dentistry.

Dietary Curcumin Attenuates Hepatic Cellular Senescence by Suppressing the MAPK/NF-κB Signaling Pathway in Aged Mice

Dietary interventions with bioactive compounds have been found to suppress the accumulation of senescent cells and senescence-associated secretory phenotypes (SASPs). One such compound, curcumin (CUR), has beneficial health and biological effects, including antioxidant and anti-inflammatory properties, but its ability to prevent hepatic cellular senescence is unclear. The objective of this study was to investigate the effects of dietary CUR as an antioxidant on hepatic cellular senescence and determine its benefits on aged mice. We screened the hepatic transcriptome and found that CUR supplementation led to the downregulation of senescence-associated hepatic gene expressions in both usually fed and nutritionally challenged aged mice. Our results showed that CUR supplementation enhanced antioxidant properties and suppressed mitogen-activated protein kinase (MAPK) signaling cascades in the liver, particularly c-Jun N-terminal kinase (JNK) in aged mice and p38 in diet-induced obese aged mice. Furthermore, dietary CUR decreased the phosphorylation of nuclear factor-κB (NF-κB), a downstream transcription factor of JNK and p38, and inhibited the mRNA expression of proinflammatory cytokines and SASPs. The potency of CUR administration was demonstrated in aged mice via enhanced insulin homeostasis along with declined body weight. Taken together, these results suggest that CUR supplementation may be a nutritional strategy to prevent hepatic cellular senescence.

PTPN2 targets TAK1 for dephosphorylation to improve cellular senescence and promote adipose tissue browning in T2DM

Introduction: The energy imbalance when energy intake exceeds expenditure acts as an essential factor in the development of insulin resistance (IR). The activity of brown adipose tissue, which is involved in the dissipation of energy via heat expenditure decreases under type 2 diabetic mellitus (T2DM) state when the number of pathological aging adipocytes increases. Protein tyrosine phosphatase non-receptor type 2 (PTPN2) regulates several biological processes by dephosphorylating several cellular substrates; however, whether PTPN2 regulates cellular senescence in adipocytes and the underlying mechanism has not been reported. Methods: We constructed a model of type 2 diabetic mice with PTPN2 overexpression to explore the role of PTPN2 in T2DM. Results: We revealed that PTPN2 facilitated adipose tissue browning by alleviating pathological senescence, thus improving glucose tolerance and IR in T2DM. Mechanistically, we are the first to report that PTPN2 could bind with transforming growth factor-activated kinase 1 (TAK1) directly for dephosphorylation to inhibit the downstream MAPK/NF-κB pathway in adipocytes and regulate cellular senescence and the browning process subsequently. Discussion: Our study revealed a critical mechanism of adipocytes browning progression and provided a potential target for the treatment of related diseases.

S-sulfhydration of SIRT3 combats BMSC senescence and ameliorates osteoporosis via stabilizing heterochromatic and mitochondrial homeostasis

Senescence of bone marrow mesenchymal stem cells (BMSCs) is one of the leading causes of osteoporosis. SIRT3, an essential NAD-dependent histone deacetylase, is highly correlated with BMSC senescence-mediated bone degradation and mitochondrial/heterochromatic disturbance. S-sulfhydration of cysteine residues favorably enhances SIRT3 activity by forming persulfides. Nevertheless, the underlying molecular mechanism of SIRT3 S-sulfhydration on mitochondrial/heterochromatic homeostasis involved in BMSC senescence remains unknown. Here, we demonstrated that CBS and CSE, endogenous hydrogen sulfide synthases, are downregulated with BMSC senescence. Exogenous H₂S donor NaHS-mediated SIRT3 augmentation rescued the senescent phenotypes of BMSCs. Conversely, SIRT3 deletion accelerated oxidative stress-induced BMSC senescence through mitochondrial dysfunction and the detachment of the heterochromatic protein H3K9me3 from the nuclear envelope protein Lamin B1. H₂S-mediated SIRT3 S-sulfhydration modification rescued the disorganized heterochromatin and fragmented mitochondria induced by the S-sulfhydration inhibitor dithiothreitol, thus leading to elevated osteogenic capacity and preventing BMSC senescence. The antisenescence effect of S-sulfhydration modification on BMSCs was abolished when the CXXC sites of the SIRT3 zinc finger motif were mutated. In vivo, aged mice-derived BMSCs pretreated with NaHS were orthotopically transplanted to the ovariectomy-induced osteoporotic mice, and we proved that SIRT3 ameliorates bone loss by inhibiting BMSC senescence. Overall, our study for the first time indicates a novel role of SIRT3 S-sulfhydration in stabilizing heterochromatin and mitochondrial homeostasis in counteracting BMSC senescence, providing a potential target for the treatment of degenerative bone diseases.

Biomarkers of aging

Aging biomarkers are a combination of biological parameters to (i) assess age-related changes, (ii) track the physiological aging process, and (iii) predict the transition into a pathological status. Although a broad spectrum of aging biomarkers has been developed, their potential uses and limitations remain poorly characterized. An immediate goal of biomarkers is to help us answer the following three fundamental questions in aging research: How old are we? Why do we get old? And how can we age slower? This review aims to address this need. Here, we summarize our current knowledge of biomarkers developed for cellular, organ, and organismal levels of aging, comprising six pillars: physiological characteristics, medical imaging, histological features, cellular alterations, molecular changes, and secretory factors. To fulfill all these requisites, we propose that aging biomarkers should qualify for being specific, systemic, and clinically relevant.

Pleiotropic effects of BAFF on the senescence-associated secretome and growth arrest

Senescent cells release a variety of cytokines, proteases, and growth factors collectively known as the senescence-associated secretory phenotype (SASP). Sustained SASP contributes to a pattern of chronic inflammation associated with aging and implicated in many age-related diseases. Here, we investigated the expression and function of the immunomodulatory cytokine BAFF (B-cell activating factor; encoded by the TNFSF13B gene), a SASP protein, in multiple senescence models. We first characterized BAFF production across different senescence paradigms, including senescent human diploid fibroblasts (WI-38, IMR-90) and monocytic leukemia cells (THP-1), and tissues of mice induced to undergo senescence. We then identified IRF1 (interferon regulatory factor 1) as a transcription factor required for promoting TNFSF13B mRNA transcription in senescence. We discovered that suppressing BAFF production decreased the senescent phenotype of both fibroblasts and monocyte-like cells, reducing IL6 secretion and SA-β-Gal staining. Importantly, however, the influence of BAFF on the senescence program was cell type-specific: in monocytes, BAFF promoted the early activation of NF-κB and general SASP secretion, while in fibroblasts, BAFF contributed to the production and function of TP53 (p53). We propose that BAFF is elevated across senescence models and is a potential target for senotherapy.

Lycopene attenuates D-galactose-induced cognitive decline by enhancing mitochondrial function and improving insulin signalling in the brains of female CD-1 mice

The incidence of neurodegenerative diseases is severely increasing with ageing. Lycopene (LYC), a carotenoid pigment, has been reported to have antioxidant, anti-inflammatory and neuroprotective properties. In the present study, we aimed to investigate the ameliorative effect of LYC on D-galactose (D-gal) induced cognitive defects and the underlying mechanisms. Forty-five female CD-1 mice (two months old) were separated into three groups to be fed with either a normal diet or a LYC diet (0.03%, w/w, mixed into normal diet). Meanwhile, the mice were treated by intraperitoneal injection of normal saline or D-gal 150 mg/kg/day for 8 weeks. The behavioural test results indicated that LYC alleviated D-gal induced cognitive impairments. LYC ameliorated brain ageing by decreasing the number of SA-β-gal- stained neurons, downregulating the protein expression of the cellular senescence associated genes P19/P21/P53, increasing the activities of the antioxidant enzymes GSH and SOD, downregulating the level of ROS, inhibiting the activation of MAPKs signalling and downregulating the levels of the inflammatory cytokines IL-1β and TNFɑ in mouse brains. LYC ameliorated synaptic dysfunction by increasing the expression of the neurotrophic factor BDNF and synaptic proteins. Moreover, LYC attenuated D-gal-induced mitochondrial morphological damage, and promoted the expression of mitochondrial functional proteins. LYC also promoted insulin signal transduction in mouse brains through the regulation of IRS-1/AKT/GSK3β signalling.

Colchicine Protects against Ethanol-Induced Senescence and Senescence-Associated Secretory Phenotype in Endothelial Cells

Inflammaging is a potential risk factor for cardiovascular diseases. It results in the development of thrombosis and atherosclerosis. The accumulation of senescent cells in vessels causes vascular inflammaging and contributes to plaque formation and rupture. In addition to being an acquired risk factor for cardiovascular diseases, ethanol can induce inflammation and senescence, both of which have been implicated in cardiovascular diseases. In the current study, we used colchicine to abate the cellular damaging effects of ethanol on endothelial cells. Colchicine prevented senescence and averted oxidative stress in endothelial cells exposed to ethanol. It lowered the relative protein expression of aging and senescence marker P21 and restored expression of the DNA repair proteins KU70/KU80. Colchicine inhibited the activation of nuclear factor kappa B (NFκ-B) and mitogen activated protein kinases (MAPKs) in ethanol-treated endothelial cells. It reduced ethanol-induced senescence-associated secretory phenotype. In summary, we show that colchicine ameliorated the ethanol-caused molecular events, resulting in attenuated senescence and senescence-associated secretory phenotype in endothelial cells.

Canagliflozin Delays Aging of HUVECs Induced by Palmitic Acid via the ROS/p38/JNK Pathway

Vascular aging is an important factor contributing to cardiovascular diseases, such as hypertension and atherosclerosis. Hyperlipidemia or fatty accumulation may play an important role in vascular aging and cardiovascular diseases. Canagliflozin (CAN), a sodium-glucose cotransporter inhibitor, can exert a cardiovascular protection effect that is likely independent of its hypoglycemic activities; however, the exact mechanisms remain undetermined. We hypothesized that CAN might have protective effects on blood vessels by regulating vascular aging induced by hyperlipidemia or fatty accumulation in blood vessel walls. In this study, which was undertaken on the basis of aging and inflammation, we investigated the protective effects and mechanisms of CAN in human umbilical vein endothelial cells induced by palmitic acid. We found that CAN could delay vascular aging, reduce the secretion of the senescence-associated secretory phenotype (SASP) and protect DNA from damage, as well as exerting an effect on the cell cycle of senescent cells. These actions likely occur through the attenuation of the excess reactive oxygen species (ROS) produced in vascular endothelial cells and/or down-regulation of the p38/JNK signaling pathway. In summary, our study revealed a new role for CAN as one of the sodium-dependent glucose transporter 2 inhibitors in delaying lipotoxicity-induced vascular aging by targeting the ROS/p38/JNK pathway, giving new medicinal value to CAN and providing novel therapeutic ideas for delaying vascular aging in patients with dyslipidemia.

MAPKs in the early steps of senescence implemEMTation

Evidence is accumulating that the earliest stages of the DNA damage response can direct cells toward senescence instead of other cell fates. In particular, tightly regulated signaling through Mitogen-Activated Protein Kinases (MAPKs) in early senescence can lead to a sustained pro-survival program and suppress a pro-apoptotic program. Importantly, an epithelial-to-mesenchymal Transition (EMT)-like program appears essential for preventing apoptosis and favoring senescence following DNA damage. In this review, we discuss how MAPKs might influence EMT features to promote a senescent phenotype that increases cell survival at the detriment of tissue function.

T-cell senescence: A crucial player in autoimmune diseases

Senescent T cells are proliferative disabled lymphocytes that lack antigen-specific responses. The development of T-cell senescence in autoimmune diseases contributes to immunological disorders and disease progression. Senescent T cells lack costimulatory markers with the reduction of T cell receptor repertoire and the uptake of natural killer cell receptors. Senescent T cells exert cytotoxic effects through the expression of perforin, granzymes, tumor necrosis factor, and other molecules without the antigen-presenting process. DNA damage accumulation, telomere damage, and limited DNA repair capacity are important features of senescent T cells. Impaired mitochondrial function and accumulation of reactive oxygen species contribute to T cell senescence. Alleviation of T-cell senescence could provide potential targets for the treatment of autoimmune diseases.

Cellular senescence: when growth stimulation meets cell cycle arrest

At the very moment of cell-cycle arrest, the cell is not senescent yet. For several days in cell culture, the arrested cell is acquiring a senescent phenotype. What is happening during this geroconversion? Cellular enlargement (hypertrophy) and hyperfunctions (lysosomal and hyper-secretory) are hallmarks of geroconversion.

A competitive precision CRISPR method to identify the fitness effects of transcription factor binding sites

Here we describe a competitive genome editing method that measures the effect of mutations on molecular functions, based on precision CRISPR editing using template libraries with either the original or altered sequence, and a sequence tag, enabling direct comparison between original and mutated cells. Using the example of the MYC oncogene, we identify important transcriptional targets and show that E-box mutations at MYC target gene promoters reduce cellular fitness.

Low-dose tributyltin triggers human chondrocyte senescence and mouse articular cartilage aging

Tributyltin (TBT) is known as an endocrine-disrupting chemical. This study investigated the effects and possible mechanisms of TBT exposure on inducing human articular chondrocyte senescence in vitro at the human-relevant concentrations of 0.01-0.5 μM and mouse articular cartilage aging in vivo at the doses of 5 and 25 μg/kg/day, which were 5 times lower than the established no observed adverse effect level (NOAEL) and equal to NOAEL, respectively. TBT significantly increased the senescence-associated β-galactosidase activity and the protein expression levels of senescence markers p16, p53, and p21 in chondrocytes. TBT induced the protein phosphorylation of both p38 and JNK mitogen-activated protein kinases in which the JNK signaling was a main pathway to be involved in TBT-induced chondrocyte senescence. The phosphorylation of both ataxia-telangiectasia mutated (ATM) and histone protein H2AX (termed γH2AX) was also significantly increased in TBT-treated chondrocytes. ATM inhibitor significantly inhibited the protein expression levels of γH2AX, phosphorylated p38, phosphorylated JNK, p16, p53, and p21. TBT significantly stimulated the mRNA expression of senescence-associated secretory phenotype (SASP)-related factors, including IL-1β, TGF-β, TNF-α, ICAM-1, CCL2, and MMP13, and the protein expression of GATA4 and phosphorylated NF-κB-p65 in chondrocytes. Furthermore, TBT by oral gavage for 4 weeks in mice significantly enhanced the articular cartilage aging and abrasion. The protein expression of phosphorylated p38, phosphorylated JNK, GATA4, and phosphorylated NF-κB-p65, and the mRNA expression of SASP-related factors were enhanced in the mouse cartilages. These results suggest that TBT exposure can trigger human chondrocyte senescence in vitro and accelerating mouse articular cartilage aging in vivo.

Higher Oxidative Stress in Endometriotic Lesions Upregulates Senescence-Associated p16ink4a and β-Galactosidase in Stromal Cells

Endometriosis affects a significant proportion of women worldwide; however, no definitive cure for this disease has been discovered to date. Oxidative stress promotes endometriotic lesion maintenance in the peritoneal cavity in women. Furthermore, there is evidence of the mitogen-activated protein kinase (MAPK) signaling pathway and senescence involvement in the physiopathogenesis of endometriosis. Reactive oxygen species (ROS) cause oxidative damage and are expected to trigger senescence in the endometrium while also causing alterations in MAPK signaling. However, the role of ROS in the senescence-associated phenotype in endometriosis remains unknown. In this context, this study attempted to delineate the pathways linking ROS to senescence in endometrial and endometriotic lesions of healthy individuals and those with endometriosis. Our results indicate a higher presence of ROS in endometriotic lesions, and the upregulation of MAPK. Furthermore, we show that endometriotic lesions in stromal cells stimulated with hydrogen peroxide develop more senescence traits than eutopic and non-endometriosis endometrium. Overall, endometriotic cells respond differently to extracellular distress. Our contribution to further research in this field contributed to the roadmap of endometriosis' search for alternative treatments.

Multiple myeloma, a quintessential malignant disease of aging: a geroscience perspective on pathogenesis and treatment

Multiple myeloma (MM) is an incurable plasma cell malignancy, which is predominantly a disease of older adults (the median age at diagnosis is 70 years). The slow progression from asymptomatic stages and the late-onset of MM suggest fundamental differences compared to many other hematopoietic system-related malignancies. The concept discussed in this review is that age-related changes at the level of terminally differentiated plasma cells act as the main risk factors for the development of MM. Epigenetic and genetic changes that characterize both MM development and normal aging are highlighted. The relationships between cellular aging processes, genetic mosaicism in plasma cells, and risk for MM and the stochastic processes contributing to clonal selection and expansion of mutated plasma cells are investigated. In line with the DNA damage accumulation theory of aging, in this review, the evolution of monoclonal gammopathy to symptomatic MM is considered. Therapeutic consequences of age-dependent comorbidities that lead to frailty and have fundamental influence on treatment outcome are described. The importance of considering geriatric states when planning the life-long treatment course of an elderly MM patient in order to achieve maximal therapeutic benefit is emphasized.