Expression Of Senescence-related Genes Research Articles

Identification of stable housekeeping genes in mouse liver for studying carbon tetrachloride-induced injury and cellular senescence

Acute liver injury (ALI) presents a challenging problem worldwide, prompting extensive research efforts. Cellular senescence has been found to be induced following ALI, and targeting cellular senescence has shown therapeutic potential. Therefore, understanding the expression of senescence-related genes in ALI can help to explore pathogenesis and treatment of this common disease. Carbon tetrachloride (CCl4) is commonly used to study ALI. Although polymerase chain reaction (PCR) is a convenient and economical molecular biology technique widely used in basic medicine, research on selecting suitable reference genes to obtain objective and reproducible PCR data is scarce. Moreover, evidence supporting the choice of reference genes for experimental studies of CCl4-induced ALI and hepatic senescence in mice is limited. In this study, we obtained murine livers at four time points (0, 12, 24, and 48 h) following CCl4 treatment. We used five algorithms (geNorm, BestKeeper, NormFinder, delta Ct, and RefFinder) to rank 12 candidate genes in real-time reverse-transcription quantitative PCR (RT-qPCR) experiments. Focusing on cellular senescence in this model, we adopted four senescence-associated secretory phenotype (SASP) genes (Il6, Il1b, Ccl2, and Ccl5) as target genes. Our results confirmed Gapdh and Tbp as suitable reference genes in murine CCl4-induced ALI models. Furthermore, we provide a table of published studies recommending reference genes for various liver disease models. This study provides a valuable reference for enhancing the reliability and reproducibility of ALI molecular findings.

Identification of Cellular Senescence-Related Critical Genes and Molecular Classification and Revealing the Drug-Resistant Therapeutic Effect of IGFBP2 in Chronic Myeloid Leukemia.

The occurrence and development of hematologic tumors are closely linked to cellular senescence. However, the molecular characteristics associated with this phenomenon in chronic myeloid leukemia (CML) have not been thoroughly investigated. The cellular senescence score was calculated using gene set variation analysis. Consensus clustering algorithm was used to identify the molecular subtypes associated with cellular senescence. Clinical samples were collected for sequencing analysis to verify the expression of critical cellular senescence-related genes (CSRG). The effect of targeted inhibition of IGFBP2 on the malignant phenotype of CML-resistant cells was studied by cell experiments. The cellular senescence score in CML samples was significantly lower compared to normal samples. Higher expression of immune checkpoint markers correlated with increased cellular senescence scores. We identified two distinct molecular subtypes (C1 and C2) related to cellular senescence. The C1 subtype exhibited enhanced metabolic function and DNA damage repair capacity, while the C2 subtype showed higher infiltration of immune effector cells and activity in immune-related signaling pathways. We also discovered a group of drugs that displayed significant sensitivity differences between these two molecular subtypes, with the C2 subtype showing greater responsiveness to immunotherapy. Four critical cellular senescence-related genes (CSRGs), namely IGFBP2, IL7R, PLAU, and SUN1 demonstrated high diagnostic value for CML. We validated the expression levels of these four genes using clinical samples and confirmed through cell experiments that targeted inhibition of IGFBP2 effectively suppressed proliferation of resistant CML cells, promoted apoptosis, and enhanced therapeutic sensitivity to imatinib. Our study conducted a comprehensive analysis on CSRG expression characteristics in CML and explored potential correlations between cellular senescence and immune function. The identification of molecular subtypes provides valuable insights into assessing individual patients' biological characteristics for guiding clinical treatment decisions. Additionally, IGFBP2has emerged as a promising therapeutic target for therapy-resistant cases of CML.

Systemic comparison of molecular characteristics in different skin fibroblast senescent models.

Senescent human skin primary fibroblast (FB) models have been established for studying aging-related, proliferative, and inflammatory skin diseases. The aim of this study was to compare the transcriptome characteristics of human primary dermal FBs from children and the elderly with four senescence models. Human skin primary FBs were obtained from healthy children (FB-C) and elderly donors (FB-E). Senescence models were generated by ultraviolet B irradiation (FB-UVB), D-galactose stimulation (FB-D-gal), atazanavir treatment (FB-ATV), and replication exhaustion induction (FB-P30). Flow cytometry, immunofluorescence staining, real-time quantitative polymerase chain reaction, co-culturing with immune cells, and bulk RNA sequencing were used for systematic comparisons of the models. In comparison with FB-C, FB-E showed elevated expression of senescence-related genes related to the skin barrier and extracellular matrix, proinflammatory factors, chemokines, oxidative stress, and complement factors. In comparison with FB-E, FB-UVB and FB-ATV showed higher levels of senescence and expression of the genes related to the senescence-associated secretory phenotype (SASP), and their shaped immune microenvironment highly facilitated the activation of downstream immune cells, including T cells, macrophages, and natural killer cells. FB-P30 was most similar to FB-E in terms of general transcriptome features, such as FB migration and proliferation, and aging-related characteristics. FB-D-gal showed the lowest expression levels of senescence-related genes. In comparisons with the single-cell RNA sequencing results, FB-E showed almost complete simulation of the transcriptional spectrum of FBs in elderly patients with atopic dermatitis, followed by FB-P30 and FB-UVB. FB-E and FB-P30showed higher similarity with the FBs in keloids. Each senescent FB model exhibited different characteristics. In addition to showing upregulated expression of natural senescence features, FB-UVB and FB-ATV showed high expression levels of senescence-related genes, including those involved in the SASP, and FB-P30showed the greatest similarity with FB-E. However, D-galactose-stimulated FBs did not clearly present aging characteristics.

Urolithin A alleviates cell senescence by inhibiting ferroptosis and enhances corneal epithelial wound healing.

To analyze the therapeutic effect and mechanism of Urolithin A (UA) on delayed corneal epithelial wound healing. The C57BL/6 mice were continuously exposed to hyperosmotic stress (HS) for 7 days followed by the removal of central corneal epithelium to establish a delayed corneal epithelial wound healing model in vivo. In vitro, the human corneal epithelial cell line (HCE-T) was also incubated under HS. UA was administered in vivo and in vitro to study its effects on corneal epithelial cells. Senescence-associated β-galactosidase (SA-β-gal) staining was performed to detect the level of cell senescence. Transcriptome sequencing (RNA-seq) was conducted to elucidate the molecular mechanism underlying the effect of UA on corneal epithelial repair. Additionally, the expression of senescence-related and ferroptosis-related genes and the levels of lipid peroxides (LPO) and malondialdehyde (MDA) were measured. Hyperosmotic stress (HS) significantly increased the proportion of SA-β-gal staining positive cells in corneal epithelial cells and upregulated the expression of p16 and p21 (p < 0.0001). Topical application of UA decreased the accumulation of senescent cells in corneal epithelial wounds and promoted epithelial wound healing. The results of RNA-seq of HS-induced corneal epithelial cells showed that the ferroptosis pathway was significantly dysregulated. Further investigation revealed that UA decreased the level of oxidative stress in HCE-T cells, including the levels of LPO and MDA (p < 0.05). Inhibition of ferroptosis significantly prevented cellular senescence in HS-induced HCE-T cells. In this study, UA promoted HS-induced delayed epithelial wound healing by reducing the senescence of corneal epithelial cells through the inhibition of ferroptosis.

Mesenchymal stem cells-derived exosomes alleviate senescence of retinal pigment epithelial cells by activating PI3K/AKT-Nrf2 signaling pathway in early diabetic retinopathy

Diabetic retinopathy (DR) is a major cause of vision loss and blindness in adults. Cellular senescence was involved in the pathogenesis of early-stage DR and is positively correlated with progression. Thus, our study aimed at exploring the effect and potential mechanism of Mesenchymal stem cells-derived exosomes (MSCs-EXOs) on Retinal Pigment Epithelial (RPE) cells senescence at an early stage of DR in vivo and in vitro. ARPE-19 cells were incubated in high glucose (HG) medium mixed with MSCs-EXOs to observe the changes in cell viability. Senescence-associated β-galactosidase (SA-β-gal) staining, Western blot and qRT-PCR were used to assess the expression of senescence-related genes and antioxidant mediators. Quantitative Real-Time polymerase chain reaction (qRT-PCR), Optical coherence tomography (OCT) Hematoxylin and eosin (HE) staining and Electroretinogram (ERG) were respectively used to verify cellular senescence, the structure and function of the retina. Our findings demonstrated that MSCs-EXOs inhibited HG-induced senescence in ARPE-19 cells. Furthermore, MSCs-EXOs reduced HG-induced cell apoptosis and oxidative stress levels while promoting cell proliferation. Mechanistically, HG suppressed PI3K/AKT phosphorylation as well as nuclear factor erythroid 2-related factor 2 (Nrf2) expression along with its downstream target gene expression in ARPE-19 cells. However, MSCs-EXOs reversed these changes by alleviating cellular senescence while enhancing antioxidant activity. In line with our results in vitro, MSCs-EXOs significantly ameliorated hyperglycemia-induced senescence in DR mice by downregulating mRNA expression of P53, P21, P16, and SASP. Additionally, MSCs-EXOs improved the functional and structural integrity of the retina in DR mice. Our study revealed the protective effect of MSCs-EXOs on cellular senescence, offering new insights for the treatment of DR.

Identifying and evaluating a disulfidptosis-related gene signature to predict prognosis in colorectal adenocarcinoma patients.

Disulfidptosis, a regulated form of cell death, has been recently reported in cancers characterized by high SLC7A11 expression, including invasive breast carcinoma, lung adenocarcinoma, and hepatocellular carcinoma. However, its role in colon adenocarcinoma (COAD) has been infrequently discussed. In this study, we developed and validated a prognostic model based on 20 disulfidptosis-related genes (DRGs) using LASSO and Cox regression analyses. The robustness and practicality of this model were assessed via a nomogram. Subsequent correlation and enrichment analysis revealed a relationship between the risk score, several critical cancer-related biological processes, immune cell infiltration, and the expression of oncogenes and cell senescence-related genes. POU4F1, a significant component of our model, might function as an oncogene due to its upregulation in COAD tumors and its positive correlation with oncogene expression. In vitro assays demonstrated that POU4F1 knockdown noticeably decreased cell proliferation and migration but increased cell senescence in COAD cells. We further investigated the regulatory role of the DRG in disulfidptosis by culturing cells in a glucose-deprived medium. In summary, our research revealed and confirmed a DRG-based risk prediction model for COAD patients and verified the role of POU4F1 in promoting cell proliferation, migration, and disulfidptosis.

RADT-10. LITHIUM TREATMENT PROTECTS MICROGLIA AND NEWLY GENERATED NEURONAL POPULATIONS IN A MOUSE MODEL OF CRANIAL RADIOTHERAPY

Abstract BACKGROUND Radiotherapy remains a cornerstone of the treatment of high-grade brain tumors. However, while lifesaving, it results in long-term complications in 50-96 % of the treated individuals, where cognitive deficits are particularly debilitating. Currently, no treatments or preventive strategies are available to avert these deficits. Lithium (Li), long used to treat bipolar affective disorder, has been shown to reduce radiation-induced cognitive deficits in rodent models by preventing apoptosis of the neuronal stem and progenitor cells in the hippocampus and stimulating their proliferation. This work aimed to further elucidate the mechanisms behind the protective and pro-regenerative actions of Li in the irradiated young brain. METHODS Postnatal day (PD) 21, C57BL6/J mice were injected intraperitoneally with Li chloride (4 mmol/kg) and kept on a Li carbonate-containing diet for 4 weeks. Control animals were injected with saline and administered an equivalent control diet. On PD 25, the animals were administered a single-dose whole-brain radiation of 8 Gy and were subsequently sacrificed at different time points, spanning from 2 weeks to 1 year. At sacrifice, the hippocampi were harvested for single-cell RNA sequencing using a novel, 2-step protocol to harvest viable cells of all types, including neurons. RESULTS The results showed that radiation triggered the expression of senescence-related genes in the hippocampal microglia (e.g., Cdkn1a, Ccl12), which Li has prevented through the activation of the Bcl2 family of genes. Moreover, they corroborate the protective effect of Li on newly generated hippocampal neurons, which undergo remodeling over time, leading to the emergence of new subpopulations. CONCLUSIONS This work represents another advancement towards understanding the action of Li in the irradiated brain and confirms its potential to become the first pharmacological treatment for radiation-induced complications.

Comparison of infant bone marrow- and umbilical cord-derived mesenchymal stem cells in multilineage differentiation

We compared infant bone marrow-derived mesenchymal stem cells (infant BMSCs) with umbilical cord-derived mesenchymal stem cells (UCSCs) by assessing multilineage differentiation. Proliferation was gauged through changes in cell numbers and doubling time. Senescence-related genes (p16, p21, and p53), senescence-associated β-galactosidase (SA-β-gal), and γH2AX immunofluorescence determined senescence presence. Superoxide dismutases (SODs) and genes related to various differentiations were analyzed using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Differentiation was confirmed through histochemical, immunohistochemical, and immunofluorescence staining. Infant BMSCs surpassed UCSCs in proliferation. Infant BMSCs exhibited lower senescence-related gene expression at late passages, upregulated antioxidant enzymes during early passages, and reduced SA-β-gal staining. Chondrogenic gene expression (SOX9, COL2, and COL10) was enhanced in infant BMSCs, along with improved immunohistochemical staining. Infant BMSCs showed higher expression of osteogenic (ALP and OCN) and adipogenic (PPARγ and LPL) genes, confirmed by histochemical staining. However, UCSCs had higher expression of tenogenic genes (MMP3, SCX, DCN, and TNC). Hepatogenic differentiation potential was similar, with no significant difference in hepatogenic gene expression (ALB and TAT). Compared to UCSCs, infant BMSCs demonstrated superior proliferation, reduced senescence, increased antioxidant capacity, and enhanced differentiation potential toward chondrogenic, osteogenic, and adipogenic lineages.

The Natural Flavanoid Senolytic Fisetin Mitigates Age-Related Changes in Frailty, Grip Strength, and the Skeletal Muscle Transcriptome in Old Mice

Background: Changes in skeletal muscle (SKM) with aging are characterized, in part, by reduced SKM strength and altered gene expression, both of which contribute to increased frailty. The age-related accumulation of excess senescent cells promotes the sequela of SKM aging and contributes to increased frailty. Thus, reducing senescent cell burden represents a promising therapeutic approach to improve SKM function and reduce frailty with aging. Senolytics are compounds that clear excess senescent cells. Currently available synthetic pharmacological senolytic agents harbor poor safety profiles and have low translational application; thus, new approaches are required. Fisetin (FIS) is a natural flavonoid senolytic compound that may fit this need. However, whether FIS supplementation lowers frailty and mitigates the sequela of SKM aging remains unknown. Hypothesis: FIS supplementation in old mice will ameliorate age-related changes in frailty, SKM strength, and senescence-related gene expression in SKM. Methods: We assessed frailty (via a validated frailty index) and SKM strength (via forelimb grip strength) in old (27 mo) male and female C57BL6/N mice following intermittent oral supplementation of either FIS (OFIS, N=39/19 female; 100 mg/kg/day in vehicle [10% EtOH; 30% PEG400; 60% Phosal 50 PG]; 1 week on — 2 weeks off — 1 week on) or vehicle (OC, N=31/13 female). mRNA expression was assessed in isolated quadriceps SKM via bulk RNA sequencing (N=10/group; 5 female). Results were also compared to a young (6 mo) control reference group (YC, N=10; 5 female). Sex differences were not observed, therefore, data were combined for male and female mice. Data are mean ± SEM. Results: Frailty was higher (OC: 0.27 ± 0.01 vs. YC: 0.01 ± 0.004; p&lt;0.05) and grip strength was lower (OC: 2.9g ± 0.01 vs. YC: 4.4g ± 0.02; p&lt;0.05) in old relative to young mice. Pathways associated with cellular senescence were enriched in SKM of OC compared to YC. Some of the most overly expressed genes with aging were related to cellular senescence (e.g., Ankrd1, Gadd45a, Cdkn1a). FIS supplementation reduced the age-related increase in frailty by ~15% (OFIS, 0.23 ± 0.01; p&lt;0.05 vs. OC) and diminished the age-related decline in grip strength by ~30% (OFIS, 3.3g ± 0.1; p&lt;0.05 vs. OC). FIS altered the overall SKM transcriptome in old mice characterized by (1) a less distinct aging phenotype vs. YC analyzed via principal component analysis; and (2) less or no longer enriched cellular senescence-related pathways. A total of six genes were different in OFIS vs. OC (p&lt;0.05; Log 2-fold change ± 0.5). Notably, Adh1 (alcohol dehydrogenase 1; positively associated with longevity) was higher and Ddit4 (DNA damage inducible transcript 4; positively related to DNA damage-induced senescence) was lower. Conclusions: Intermittent oral supplementation with FIS may be an effective therapeutic strategy to treat the sequela of SKM aging and frailty. However, to elicit greater changes in frailty and SKM strength with aging, a stronger or longer FIS dosing paradigm may be required. F32 HL167552; K01 DK115524; AHA 23CDA1056582; F31 HL165885; F31 HL164004; R01 AG055822-S1; K99 HL159241. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Comprehensive analysis and prognostic assessment of senescence-associated genes in bladder cancer

BackgroundThe prevalence and mortality of bladder cancer (BLCA) present a significant medical challenge. While the function of senescence-related genes in tumor development is recognized, their prognostic significance in BLCA has not been thoroughly explored.MethodsBLCA transcriptome datasets were sourced from the TCGA and GEO repositories. Gene groupings were determined through differential gene expression and non-negative matrix factorization (NMF) methodologies. Key senescence-linked genes were isolated using singular and multivariate Cox regression analyses, combined with lasso regression. Validation was undertaken with GEO database information. Predictive models, or nomograms, were developed by merging risk metrics with clinical records, and their efficacy was gauged using ROC curve methodologies. The immune response’s dependency on the risk metric was assessed through the immune phenomenon score (IPS). Additionally, we estimated IC50 metrics for potential chemotherapeutic agents.ResultsReviewing 406 neoplastic and 19 standard tissue specimens from the TCGA repository facilitated the bifurcation of subjects into two unique clusters (C1 and C2) according to senescence-related gene expression. After a stringent statistical evaluation, a set of ten pivotal genes was discerned and applied for risk stratification. Validity tests for the devised nomograms in forecasting 1, 3, and 5-year survival probabilities for BLCA patients were executed via ROC and calibration plots. IC50 estimations highlighted a heightened responsiveness in the low-risk category to agents like cisplatin, cyclopamine, and sorafenib.ConclusionsIn summation, our research emphasizes the prospective utility of risk assessments rooted in senescence-related gene signatures for enhancing BLCA clinical oversight.

Abstract 2955: HPV E6* and senescence-related gene expression in cervical cancer

Abstract Previous work in our lab found that increased expression of the E6* variant of the HPV E6 viral protein was significantly correlated with worse response to standard-of-care chemoradiation (CRT) and progression-free survival, independently of HPV genotype. In vitro validation showed that overexpression of E6* induces senescence in an HPV 16-positive cervical cancer cell line. Given these findings, we hypothesized that increased E6* expression mediates resistance to CRT by inducing a reversible state of tumor cell senescence. We created a senescence score using ten genes that have been consistently reported in the literature as associated with senescence. Using an institutional cohort of 68 patients with cervical cancer with prospectively collected clinical outcome data, we performed bulk RNA sequencing to assess senescence scores before CRT and determine whether there is an association between senescence scores and E6* expression. Using a second institutional cohort of 35 patients with cervical cancer treated with CRT with pre and posttreatment tumor biopsies, we performed bulk RNA sequencing to evaluate the same relationship and determine whether expression of senescence-related genes was affected by CRT. Nine cervical cancer cell lines stratified into low- and high-E6* expression groups will be assessed regarding their senescence score, beta-galactosidase staining, and SASP expression before and after CRT. In our first cohort, there was no correlation between E6*:E6 expression ratio and senescence score, regardless of HPV genotype. In our second cohort, CRT increased senescence score in CRT-treated samples (p &amp;lt; 0.01), but p16INK4a expression significantly decreased compared to pre-treatment samples (p &amp;lt; 0.01). Increased senescence score was not associated with cancer recurrence. There was no significant difference in senescence scores between different HPV genotypes before therapy. Tumors that were positive for HPV 16 or HPV 18 had significantly lower senescence scores compared to HPV negative tumors (p = 0.037 and p = 0.038, respectively) after CRT. Among HPV 16-positive tumors (n = 12), there was no correlation between E6*:E6 expression ratio and senescence score before or after CRT. We found no association between senescence score and E6* expression, and between senescence score and cancer recurrence after CRT in our dataset. Additionally, our results suggest that p16INK4a might not be an appropriate senescence marker in tumors that have intrinsically high p16INK4a expression, such as in cervical cancer, reinforcing the need for a cervical cancer-specific senescence signature. We are currently testing beta-galactosidase and SASP expression in vitro and in vivo before and after CRT. Citation Format: Louise Medina Bengtsson, Matthew Inkman, Naoshad Muhammad, Leahan Castillo, Naomi Msengi, Tyler McKinnish, Nishanth Gabriel, Jin Zhang, Julie Schwarz. HPV E6* and senescence-related gene expression in cervical cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2955.

Mechanism of Bazi Bushen capsule in delaying the senescence of mesenchymal stem cells based on network pharmacology and experimental validation

Ageing is becoming an increasingly serious problem; therefore, there is an urgent need to find safe and effective anti-ageing drugs. AimsTo investigate the effects of Bazi Bushen capsule (BZBS) on the senescence of mesenchymal stem cells (MSCs) and explore its mechanism of action. MethodsNetwork pharmacology was used to predict the targets of BZBS in delaying senescence in MSCs. For in vitro studies, MSCs were treated with D-gal, BZBS, and NMN, and cell viability, cell senescence, stemness-related genes, and cell cycle were studied using cell counting kit-8 (CCK-8) assay, SA-β-galactosidase (SA-β-gal) staining, Quantitative Real-Time PCR (qPCR) and flow cytometry (FCM), respectively. Alkaline phosphatase (ALP), alizarin red, and oil red staining were used to determine the osteogenic and lipid differentiation abilities of MSCs. Finally, the expression of senescence-related genes and cyclin-related factors was detected by qPCR and western blotting. ResultsNetwork pharmacological analysis suggested that BZBS delayed cell senescence by interfering in the cell cycle. Our in vitro studies suggested that BZBS could significantly increase cell viability (P < 0.01), decrease the quantity of β-galactosidase+ cells (P < 0.01), downregulate p16 and p21 (P < 0.05, P < 0.01), improve adipogenic and osteogenic differentiation, and upregulate Nanog, OCT4 and SOX2 genes (P < 0.05, P < 0.01) in senescent MSCs. Moreover, BZBS significantly reduced the proportion of senescent MSCs in the G0/G1 phase (P < 0.01) and enhanced the expression of CDK4, Cyclin D1, and E2F1 (P < 0.05, P < 0.01, respectively). Upon treatment with HY-50767A, a CDK4 inhibitor, the upregulation of E2F1 was no longer observed in the BZBS group. ConclusionsBZBS can protect MSCs against D-gal-induced senescence, which may be associated with cell cycle regulation via the Cyclin D1/CDK4/E2F1 signalling pathway.

Hydrogen Peroxide Promotes Tomato Leaf Senescence by Regulating Antioxidant System and Hydrogen Sulfide Metabolism.

Hydrogen peroxide (H2O2) is relatively stable among ROS (reactive oxygen species) and could act as a signal in plant cells. In the present work, detached tomato leaves were treated with exogenous H2O2 at 10 mmol/L for 8 h to study the mechanism of how H2O2 regulates leaf senescence. The data indicated that H2O2 treatment significantly accelerated the degradation of chlorophyll and led to the upregulation of the expression of leaf senescence-related genes (NYC1, PAO, PPH, SGR1, SAG12 and SAG15) during leaf senescence. H2O2 treatment also induced the accumulation of H2O2 and malondialdehyde (MDA), decreased POD and SOD enzyme activities and inhibited H2S production by reducing the expression of LCD1/2 and DCD1/2. A correlation analysis indicated that H2O2 was significantly and negatively correlated with chlorophyll, the expression of leaf senescence-related genes, and LCD1/2 and DCD1/2. The principal component analysis (PCA) results show that H2S showed the highest load value followed by O2•-, H2O2, DCD1, SAG15, etc. Therefore, these findings provide a basis for studying the role of H2O2 in regulating detached tomato leaf senescence and demonstrated that H2O2 plays a positive role in the senescence of detached leaves by repressing antioxidant enzymes and H2S production.

Analysis of Expression Status and Relationship Between Senescence-related Genes and Pancreatic Function-related Genes in Human Islets of Langerhans from Donors of Various Ages.

Although studies on senescence-related genes using human islets of Langerhans have been performed, the expression of senescence-related genes and their association with functional genes in islets remain insufficiently investigated. We aimed to determine whether and what types of senescent-related genes are expressed in islets and identify their correlations with pancreatic function-related genes by using islets isolated for transplantation from individuals of various ages. Islets from deceased donors of both sexes and different ages were used for analysis. The expression status of senescence-related genes (glutaminase 1, interleukin 6, interleukin 8, cyclin-dependent kinase inhibitor 2A, cyclin-dependent kinase inhibitor 1A, and senescence-associated beta-galactosidase) and pancreatic function-related genes (glucagon and insulin) was examined by reverse transcription-quantitative polymerase chain reaction, and their relationships with age were investigated. We obtained isolated human islets from 18 deceased multiorgan donors. There was no correlation between donor age and expression of any of the senescence-related genes. Regarding correlations between donor age and pancreatic function-related genes, age was positively correlated only with INS (r=0.49, p=0.03). INS expression was not correlated with that of GLS1 (r=0.23, p=0.34), IL6 (r=-0.06, p=0.79), or IL8 (r=-0.1, p=0.12), but positively related with p16 (r=0.89, p<0.0001), p21 (r=0.51, p=0.02), and SA-β-gal (r=0.52, p=0.02). We showed the functional potential even of aged islets, which were originally thought to be functionally impaired. We were unable to identify any senescence-related genes expressed in islets from donors of different ages. Therefore, a new index is needed to evaluate not only actual chronological age but also organ- and cell-specific age.

Vitamin C, doxycycline, and azithromycin (VDA) targeted changes in cellular senescence-related genes in human adipose-derived mesenchymal stem cells.

Adipose-derived Mesenchymal stem cells (ASCs) have garnered attention for their regenerative potential; therefore, their cellular senescence-related gene expression remains crucial in therapeutic contexts. Nowadays, combination therapies have shown promising results in reducing senescent cells. This study investigated the effects of vitamin C, doxycycline, and azithromycin co-treatment on the key cellular senescence-associated genes in ASCs. Human ASCs were cultured and treated for 24 hr with vitamin C, doxycycline, azithromycin, and a combination of three drugs. Total RNAs were extracted, and the expression of p21, p16, Nanog, Oct4, and Sox2 genes was assessed using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Additionally, cell cycle alterations were analyzed via flow cytometry after treatment with these compounds. Notably, vitamin C treatment resulted in a significant down-regulation of p21 gene expression (P<0.01), implicating the potential role of vitamin C in promoting cell cycle progression. Doxycycline treatment led to a significant up-regulation of p21 and p16 gene expression (P<0.05), as it has previously been shown to induce cell cycle arrest. Similarly, azithromycin treatment predominantly increased p21 expression (P<0.05). Besides, cell cycle analysis revealed that each compound had changed the distribution of cells across different phases of the cell cycle. The combined use of all three drugs yielded intricate interactions, suggesting a complex yet promising approach to future research. According to our findings, the major difference in the combination drug-treated group (VDA) can be explained by the neutralizing effect of these three components in the environment.

Plasma membrane-localized hexose transporter OsSWEET1b, affects sugar metabolism and leaf senescence.

OsSWEET1b is a hexose transporter protein, which localized in cell membranes and interacting with itself to form homodimer and knockout of OsSWEET1b resulted in reduced leaves sugar content and accelerating leaf senescence. In the rice genome, the SWEET gene family contains 21 homologous members, but the role of some of them in rice growth and development is still unknown. The function of the sugar transporter OsSWEET1b protein in rice was identified in this research. Expression analysis showed that the expression levels of OsSWEET1b in leaves were higher than that in other tissues. The hexose transport experiment confirmed that OsSWEET1b has glucose and galactose transporter activity in yeast. Subcellular localization indicates that OsSWEET1b protein was targeted to the plasma membrane and BiFC analysis showed that OsSWEET1b interacts with itself to form homodimers. Functional analysis demonstrated that the ossweet1b mutant plants were have reduced the sucrose, glucose, fructose, starch and galactose contents, and induced carbon starvation-related gene expression, which might lead to carbon starvation in leaves at filling stage. The ossweet1b knockout plants showed decreased chlorophyll content and antioxidant enzyme activity, and increased ROS accumulation in leaves, leading to leaf cell death and premature senescence phenotype at filling stage. In ossweet1b mutants, the leaf senescence-related gene expression levels were increased and the abundance of photosynthesis-related proteins was decreased. Loss of OsSWEET1b were affected the starch, sucrose metabolism and carbon fixation in photosynthetic organelles pathway by RNA-seq analysis. The destruction of OsSWEET1b function will cause sugar starvation, decreased photosynthesis and leaf senescence, which leading to reduced rice yield. Collectively, our results suggest that the OsSWEET1b plays a key role in rice leaves carbohydrate metabolism and leaf senescence.

The potential use of ascorbic acid to recover the cellular senescence of lipopolysaccharide-induced human apical papilla cells: an in vitro study.

To examine the effect of lipopolysaccharide (LPS) on cellular senescence induction of human apical papilla cells (hAPCs) and evaluate the potential use of 50 μg/ml ascorbic acid to recover cellular senescence and regenerative functions. hAPCs were treated with LPS at 1 and 10 μg/ml either with or without 50 μg/ml ascorbic acid for 48 h. The cellular senescence biomarkers were analyzed by senescence-associated β-galactosidase (SA-β-gal) staining and senescence-related gene expression, p16 and p21. Cell migration, at 12 h and 24 h, was evaluated using a scratch wound assay. Mineralization potential was assessed at 21 days using Alizarin red S staining and dentine sialophosphoprotein (DSPP) and bone sialoprotein (BSP) gene expression. 1 μg/ml and 10 μg/ml LPS stimulation for 48 h induced cellular senescence, as shown by remarkable SA-β-gal staining and p16 and p21 gene expression. The percentage of wound closure and mineralized formation was reduced. The co-incubation with ascorbic acid significantly down-regulated the level of SA-β-gal staining. The reduction of senescence-associated gene expressions was observed. Ascorbic acid improved cell migration, mineralized nodule formation, and the expression of DSPP and BSP genes in LPS-treated hAPCs. LPS significantly promoted cellular senescence on hAPCs and diminished the cell function capacity. Co-presence of ascorbic acid could impede cellular senescence and possibly improve the regenerative capacity of LPS-induced senescent hAPCs in vitro. The data support the in vitro potential benefit of ascorbic acid on cellular senescence recovery of apical papilla cells.

Cellular senescence triggers intracellular acidification and lysosomal pH alkalinized via ATP6AP2 attenuation in breast cancer cells

Several chemotherapeutic drugs induce senescence in cancer cells; however, the mechanisms underlying intracellular pH dysregulation in senescent cells remain unclear. Adenosine triphosphatase H+ transporting accessory protein 2 (ATP6AP2) plays a critical role in maintaining pH homeostasis in cellular compartments. Herein, we report the regulatory role of ATP6AP2 in senescent breast cancer cells treated with doxorubicin (Doxo) and abemaciclib (Abe). A decline in ATP6AP2 triggers aberrant pH levels that impair lysosomal function and cause immune profile changes in senescent breast cancer cells. Doxo and Abe elicited a stable senescent phenotype and altered the expression of senescence-related genes. Additionally, senescent cells show altered inflammatory and immune transcriptional profiles due to reprogramming of the senescence-associated secretory phenotype. These findings elucidate ATP6AP2-mediated cellular pH regulation and suggest a potential link in immune profile alteration during therapy-induced senescence in breast cancer cells, providing insights into the mechanisms involved in the senescence response to anticancer therapy.

Target of rapamycin (TOR) plays a role in regulating ROS-induced chloroplast damage during cucumber (Cucumis sativus) leaf senescence.

In cucumber production, delaying leaf senescence is crucial for improving cucumber yield and quality. Target of rapamycin (TOR) is a highly conserved serine/threonine protein kinase in eukaryotes, which can integrate exogenous and endogenous signals (such as cell energy state levels) to stimulate cell growth, proliferation, and differentiation. However, no studies have yet examined the regulatory role of TOR signalling in cucumber leaf senescence. In this study, the effects of TOR signalling on dark-induced cucumber leaf senescence were investigated using the TOR activator MHY1485 and inhibitor AZD8055 combined with transient transformation techniques. The results indicate that TOR responds to dark-induced leaf senescence, and alterations in TOR activity/expression influence cucumber leaf resistance to dark-induced senescence. Specifically, in plants with elevated TOR activity/expression, we observed reduced expression of senescence-related genes, less membrane lipid damage, decreased cell apoptosis, lower levels of reactive oxygen species production, and less damage to the photosynthetic system compared to the control. In contrast, in plants with reduced TOR activity/expression, we observed higher expression of senescence-related genes, increased membrane lipid damage, enhanced cell apoptosis, elevated levels of reactive oxygen species production, and more damage to the photosynthetic system. These comprehensive results underscore the critical role of TOR in regulating dark-induced cucumber leaf senescence. These findings provide a foundation for controlling premature leaf senescence in cucumber production and offer insights for further exploration of leaf senescence mechanisms and the development of more effective control methods.

Nervonic Acid Inhibits Replicative Senescence of Human Wharton's Jelly-Derived Mesenchymal Stem Cells.

Cellular senescence causes cell cycle arrest and promotes permanent cessation of proliferation. Since the senescence of mesenchymal stem cells (MSCs) reduces proliferation and multipotency and increases immunogenicity, aged MSCs are not suitable for cell therapy. Therefore, it is important to inhibit cellular senescence in MSCs. It has recently been reported that metabolites can control aging diseases. Therefore, we aimed to identify novel metabolites that regulate the replicative senescence in MSCs. Using a fecal metabolites library, we identified nervonic acid (NA) as a candidate metabolite for replicative senescence regulation. In replicative senescent MSCs, NA reduced senescence-associated β-galactosidase positive cells, the expression of senescence-related genes, as well as increased stemness and adipogenesis. Moreover, in non-senescent MSCs, NA treatment delayed senescence caused by sequential subculture and promoted proliferation. We confirmed, for the first time, that NA delayed and inhibited cellular senescence. Considering optimal concentration, duration, and timing of drug treatment, NA is a novel potential metabolite that can be used in the development of technologies that regulate cellular senescence.