The role of nuclear lamin B1 in cell proliferation and senescence

Emerging prodrug and nano-drug delivery strategies for the detection and elimination of senescent tumor cells

Tumor cellular senescence, characterized by reversible cell cycle arrest following anti-cancer therapies, presents a complex paradigm in oncology. Given that senescent tumor cells may promote angiogenesis, tumorigenesis, and metastasis, selective killing senescent cells (SCs)-a strategy termed senotherapy-has emerged as a promising approach to improve cancer treatment. However, the clinical implementation of senotherapy faces significant hurdles, including lack of precise methods for SCs identification and the potential for adverse effects associated with highly cytotoxic senolytic agents. In this account, we elucidate recent advancement in developing novel approaches for the detection and selective elimination of SCs, encompassing prodrugs, nanoparticles, and other cutting-edge drug delivery systems such as PROTAC technology and CAR T cell therapy. Furthermore, we explore the paradoxical nature of SCs, which can induce growth arrest in adjacent neoplastic cells and recruit immunomodulatory cells that contribute to tumor suppression. Therefore, we utilize SCs membrane as vehicles to elicit antitumor immunity and potentially augment existing anti-cancer therapies. Finally, the opportunities and challenges are put forward to facilitate the development and clinical transformation of SCs detection, elimination or utilization.

Cellular senescence: mechanisms and relevance to cancer and aging

Cellular senescence is an irreversible cell cycle arrest induced by stresses such as telomere shortening and oncogene activation. It acts as a tumor suppressor mechanism that prevents the proliferation of potentially tumorigenic cells. Paradoxically, senescent stromal cells that arise in the tumor microenvironment have been shown to promote tumor progression. In addition, senescent cells that accumulate in vivo over time are thought to contribute to aging and age-related diseases. These deleterious effects of senescent cells involve the secretion of bioactive molecules such as inflammatory cytokines and chemokines, a phenomenon known as the senescence-associated secretory phenotype. While the role of cellular senescence in vivo is becoming increasingly clear, the intracellular signaling pathways that induce the expression of senescent phenotypes are not fully understood. In this review, we outline senescence-associated signaling pathways and their relevance to cancer and aging.

Senescence as a molecular target in skin aging and disease

Skin aging represents a multifactorial process influenced by both intrinsic and extrinsic factors, collectively known as the skin exposome. Cellular senescence, characterized by stable cell cycle arrest and secretion of pro-inflammatory molecules, has been implicated as a key driver of physiological and pathological skin aging. Increasing evidence points towards the role of senescence in a variety of dermatological diseases, where the accumulation of senescent cells in the epidermis and dermis exacerbates disease progression. Emerging therapeutic strategies such as senolytics and senomorphics offer promising avenues to target senescent cells and mitigate their deleterious effects, providing potential treatments for both skin aging and senescence-associated skin diseases. This review explores the molecular mechanisms of cellular senescence and its role in promoting age-related skin changes and pathologies, while compiling the observed effects of senotherapeutics in the skin and discussing the translational relevance.

A high throughput, high content screen for non-toxic small molecules that reduce levels of the nuclear lamina protein, Lamin B1

Lamin B1 (LMNB1) is an intermediate filament protein that is an integral component of the nuclear lamina, a structure that is critical for nuclear organization and function. Mutations involving the lamin B1 gene cause the adult-onset demyelinating disorder, Autosomal Dominant Leukodystrophy (ADLD) which is charactered by increased lamin B1 expression. Increased LMNB1 expression is also associated with poorer outcomes in multiple cancer subtypes. Reducing LMNB1 is thus an attractive therapeutic pathway for ADLD and potentially other diseases. Here we present the results of a high throughput / high content screen (HTS/HCS) to identify small molecules that reduce LMNB1 levels. Approximately 97,000 molecules were screened using an inducible mouse fibroblast model of LMNB1 overexpression that we have previously generated. Two small molecules, Pubchem CID 662896 and CID 5308648, were identified that reduced LMNB1 in a dose dependent manner without causing cellular toxicity and corrected nuclear abnormalities associated with LMNB1 overexpression, a hallmark of ADLD. CID 662896 also reduced LMNB1 levels in ADLD patient fibroblast samples, exhibited favorable "drug-like" physicochemical properties and crossed the blood brain barrier in mouse studies. While CID 662896 may be a promising candidate for ADLD therapy, further investigations are required to determine its mechanism of action and ability to target disease relevant cell types.

INDUCTION OF EARLY PULMONARY SENESCENCE IN EXPERIMENTAL SEPSIS

ABSTRACT

Background: Sepsis continues to pose a significant threat to human life and represents a substantial financial burden. In addition to replicative stress resulting from telomeric loss, recent studies have identified multiple factors contributing to cell cycle arrest. Furthermore, our understanding of pathways associated with cellular senescence, such as CD47-mediated suppression of efferocytosis, has expanded. However, beyond in vitro experiments, the impact of cell stress during complex systemic illnesses, including sepsis, remains poorly understood. Consequently, we conducted an investigation into molecular alterations related to senescence-associated pulmonary mechanisms during experimental nonpulmonary sepsis. Methods: Male C57BL/6JRj mice were anesthetized and subjected to either control conditions (sham) or cecal ligation and puncture (CLP) to induce sepsis. Twenty-four hours or 7 d after CLP, animals were killed, and blood, bronchoalveolar fluids, and lungs were harvested and analyzed for morphological and biochemical changes. Results: Histological damage in pulmonary tissue, as well as increases in plasma levels of surfactant protein D, indicated development of alveolar-focused acute lung injury after CLP. Additionally, we observed a significant upregulation of the CD47-QPCTL-SHP-1 axis in lungs of septic mice. Whereas the expression of p16, a marker primarily indicating manifested forms of senescence, was decreased after CLP, the early marker of cellular senescence, p21, was increased in the lungs during sepsis. Later, at 7 d after CLP, pulmonary expression of CD47 and QPCTL-1 was decreased, whereas SHP-1 was significantly enhanced. Conclusion: Our findings suggest an activation of senescent-associated pathways during experimental sepsis. However, expanding the experiments to other organ systems and in vivo long-term models are necessary to further evaluate the sustained mechanisms and immunopathophysiological consequences of cellular senescence triggered by septic organ injury.

Chemically Induced Senescence Prompts Functional Changes in Human Microglia-Like Cells

In response to various stressors, cells can enter a state called cellular senescence which is characterized by irreversible cell cycle arrest and a senescence-associated secretory phenotype (SASP). The progressive accumulation of senescent glial cells in the central nervous system (CNS) with aging suggests a potential role for senescence as driver of aging and inflammation in the brain. As the main immune cell population residing in the CNS, microglia are thought to play a pivotal role in the progression of age-associated neuroinflammation. Furthermore, due to their slow turnover, microglia are highly susceptible to undergoing cellular senescence. However, current understanding of age-related changes in microglia and their impact on brain aging is limited. Due to the challenge in accessing human primary microglia and the lack of models to adequately recapitulate aging, this knowledge is predominantly limited to rodent studies. Here, we chemically induced senescence in a human immortalized microglia cell line with a cocktail of senescence-inducing molecules. We demonstrate that chemically induced senescent microglia adopt a proinflammatory phenotype, have reduced phagocytic activity, and impaired calcium activity. Our results show that chemically induced senescence can mimic features of cellular aging and can provide insight into the impact of aging and cellular senescence on human microglia.

Lamin B1 regulates RNA splicing factor expression by modulating the spatial positioning and chromatin interactions of the ETS1 gene locus

Lamin B1, a crucial component of the nuclear lamina, plays a pivotal role in chromatin organization and transcriptional regulation in eukaryotic cells. While recent studies have highlighted the connection between Lamin B1 and RNA splicing regulation, the precise molecular mechanisms remain elusive. In this study, we demonstrate that Lamin B1 depletion leads to a global reduction in splicing factor expression, as evidenced by analysis of multiple RNA-seq datasets. Motif analysis suggests that members of the ETS transcription factor family likely bind to the promoter regions of these splicing factors. Further analysis using transcription factor databases and ChIP-seq data identified ETS1 as a key regulator of splicing factor expression. Hi-C sequencing revealed that the loss of Lamin B1 disrupts inter-LAD chromatin interactions near the ETS1 gene locus, resulting in its downregulation. These findings suggest that Lamin B1 indirectly regulates RNA splicing by sustaining proper ETS1 expression, uncovering a novel link between nuclear architecture, gene regulation, and RNA splicing.

Resistance to premature senescence in the Epithelioma papulosum cyprini fish cell line is associated with the absence of PML nuclear bodies

Cell lines derived from fish tissues are resistant to premature senescence under typical culture conditions. Previously, we demonstrated that fish genomes do not have a p16INK4a/Arf locus and that the absence of this locus underlies the lack of senescence in cultured fish cells. However, other factors may also contribute to this resistance. In amniotes, promyelocytic leukemia (PML)-IV proteins are involved in the generation of PML nuclear bodies (PML NBs), which are connected with premature senescence. The lack of a pml gene in fish genomes may be involved in the mechanism of resistance to cellular senescence. Heterologous expression of human PML-IV in an Epithelioma papulosum cyprini cell line induced the formation of PML NB-like speckled structures. The cells displayed characteristic features of cellular senescence, namely, growth suppression, a large, flattened morphology, and increased SA-β-gal activity. Additionally, the levels of proinflammatory senescence-associated secretory phenotype (SASP) factors increased in the cells, suggesting a link between the absence of PML NBs and cellular resistance to senescence. Expression of the CCAT enhancer binding protein beta gene, which encodes a transcription factor of proinflammatory SASPs, was not increased, nor was there any elevation in the activity of NF-κB, a transcription factor for proinflammatory SASP factors and C/EBPβ. Epigenetic regulatory mechanisms may contribute to the induction of proinflammatory SASP factors by PML NBs.

Deciphering the role of skin aging in pigmentary disorders

Skin aging is a complex biological process involving intrinsic and extrinsic factors. Skin aging contains alterations at the tissue, cellular, and molecular levels. Currently, there is increasing evidence that skin aging occurs not only in time-dependent chronological aging but also plays a role in skin pigmentary disorders. This review provides an in-depth analysis of the impact of skin aging on different types of pigmentary disorders, including both hyperpigmentation disorders such as melasma and senile lentigo and hypopigmentation disorders such as vitiligo, idiopathic guttate hypomelanosis and graying of hair. In addition, we explore the mechanisms of skin aging on pigmentation regulation and suggest several potential therapeutic approaches for skin aging and aging-related pigmentary disorders.

Recent advances in biomarkers for senescence: Bridging basic research to clinic

In this review, we review the current status of biomarkers for aging and possible perspectives on anti-aging or rejuvenation from the standpoint of biomarkers. Aging is observed in all cells and organs, and we focused on research into senescence in the skin, musculoskeletal system, immune system, and cardiovascular system. Commonly used biomarkers include SA-βgal, cell-cycle markers, senescence-associated secretory phenotype (SASP) factors, damage-associated molecular patterns (DAMPs), and DNA-damage-related markers. In addition, each organ or cell has its specific markers. Generally speaking, a combination of biomarkers is required to define age-related changes. When considering the translation of basic research, biomarkers that are highly sensitive, highly specific, with validation and reliability as well as being non-invasive are optimal; however, currently reported markers do not fulfill the prerequisite for biomarkers. In addition, rodent models of aging do not necessarily represent human aging, and markers in rodent or cell models are not applicable in clinical settings. The prerequisite of clinically applicable biomarkers is that they provide useful information for clinical decision-making, such as predicting disease risk, diagnosing disease, monitoring disease progression, or guiding treatment decisions. Therefore, the development of non-invasive robust, reliable, and useful biomarkers in humans is necessary to develop anti-aging therapy for humans. Geriatr Gerontol Int 2025; 25: 139-147.

Targeting CRM1 for Progeria Syndrome Therapy

Hutchinson-Gilford progeria syndrome (HGPS) is a premature aging disease caused by progerin, a mutant variant of lamin A. Progerin anchors aberrantly to the nuclear envelope disrupting a plethora of cellular processes, which in turn elicits senescence. We previously showed that the chromosomal region maintenance 1 (CRM1)-driven nuclear export pathway is abnormally enhanced in patient-derived fibroblasts, due to overexpression of CRM1. Interestingly, pharmacological inhibition of CRM1 using leptomycin B rescues the senescent phenotype of HGPS fibroblasts, delineating CRM1 as a potential therapeutic target against HGPS. As a proof of concept, we analyzed the beneficial effects of pharmacologically modulating CRM1 in dermal fibroblasts from HGPS patients and the LMNAG609G/G609G mouse, using the first-in-class selective inhibitor of CRM1 termed selinexor. Remarkably, treatment of HGPS fibroblasts with selinexor mitigated senescence and promoted progerin clearance via autophagy, while at the transcriptional level restored the expression of numerous differentially-expressed genes and rescued cellular processes linked to aging. In vivo, oral administration of selinexor to the progeric mouse resulted in decreased progerin immunostaining in the liver and aorta, decreased progerin levels in most liver, lung and kidney samples analyzed by immunoblotting, and improved aortic histopathology. Collectively our data indicate that selinexor exerts its geroprotective action by at least two mechanisms: normalizing the nucleocytoplasmic partition of proteins with a downstream effect on the aging-associated transcriptome and decreasing progerin levels. Further investigation of the overall effect of selinexor on LmnaG609G/G609G mouse physiology, with emphasis in cardiovascular function is warranted, to determine its therapeutic utility for HGPS and aging-associated disorders characterized by CRM1 overactivity.

Dynamic 3D genome reorganization during senescence: defining cell states through chromatin

Cellular senescence, a cell state characterized by growth arrest and insensitivity to growth stimulatory hormones, is accompanied by a massive change in chromatin organization. Senescence can be induced by a range of physiological signals and pathological stresses and was originally thought to be an irreversible state, implicated in normal development, wound healing, tumor suppression and aging. Recently cellular senescence was shown to be reversible in some cases, with exit being triggered by the modulation of the cell's transcriptional program by the four Yamanaka factors, the suppression of p53 or H3K9me3, PDK1, and/or depletion of AP-1. Coincident with senescence reversal are changes in chromatin organization, most notably the loss of senescence-associated heterochromatin foci (SAHF) found in oncogene-induced senescence. In addition to fixed-cell imaging, chromatin conformation capture and multi-omics have been used to examine chromatin reorganization at different spatial resolutions during senescence. They identify determinants of SAHF formation and other key features that differentiate distinct types of senescence. Not surprisingly, multiple factors, including the time of induction, the type of stress experienced, and the type of cell involved, influence the global reorganization of chromatin in senescence. Here we discuss how changes in the three-dimensional organization of the genome contribute to the regulation of transcription at different stages of senescence. In particular, the distinct contributions of heterochromatin- and lamina-mediated interactions, changes in gene expression, and other cellular control mechanisms are discussed. We propose that high-resolution temporal and spatial analyses of the chromatin landscape during senescence will identify early markers of the different senescence states to help guide clinical diagnosis.

Regulation of the Cilia as a Potential Treatment for Senescence and Tumors: A Review

Millions of people worldwide die from malignant tumors every year, and the current clinical treatment is still based on radiotherapy and chemotherapy. Immunotherapy-adjuvant chemotherapy is widely applied, yet resistance to various factors persists in the management of advanced malignancies. Recently researchers have gradually discovered that the integrity of primary cilia is closely related to many diseases. The phenotypic changes in primary cilia are found in some cases of progeria, tumorigenesis, and drug resistance. Primary cilia seem to mediate signaling during these diseases. Hedgehog inhibitors have emerged in recent years to treat tumors by controlling signaling proteins on primary cilia. There is evidence for the use of anti-tumor drugs to treat senescence-related disease. Considering the close relationship between aging and obesity, as well as the obesity is the phenotype of many ciliopathies. Therefore, we speculate that some anti-tumor or anti-aging drugs can treat ciliopathies. Additionally, there is evidence suggesting that anti-aging drugs for tumor treatment, in which the process may be mediated by cilia. This review elucidates for the first time that cilia may be involved in the regulation of senescence, metabolic, tumorigenesis, and tumor resistance and hypothesizes that cilia can be regulated to treat these diseases in the future.

Quercetin as a therapeutic agent for skin problems: a systematic review and meta-analysis on antioxidant effects, oxidative stress, inflammation, wound healing, hyperpigmentation, aging, and skin cancer

Quercetin is abundant in plants and has notable pharmacological properties for skin health. This review aims to comprehensively evaluate the effects of quercetin on skin-related issues, adhering to the PRISMA guidelines and analyzing studies from ScienceDirect, Web of Science, Scopus, and PubMed. Of the 1,398 studies identified, 65 studies met the criteria for meta-analysis. The meta-analysis indicated that quercetin had powerful antioxidant properties, protecting against oxidative stress by significantly lowering levels of MDA (Z-score, 2.51), ROS (Z-score, 3.81), and LPO (Z-score, 4.46), and enhancing enzymes of GSH (Z-score, 5.46), CAT (Z-score, 5.20), and SOD (Z-score, 4.37). Quercetin acted as an anti-inflammatory by significantly suppressing protein regulators such as NF-κβ, AP-1, and MAPKs (ERK and JNK), cytokines of TNFα, IL-6, IL-1β, IL-8, and MCP-1, and enzymes of COX-2, iNOS, and MPO, while upregulating the cytokine IL-10. Additionally, quercetin significantly suppressed IL-4 (Z-score, 3.16) and IFNγ (Z-score, 3.76) cytokines involved in chronic inflammation of atopic dermatitis. Quercetin also supported wound healing by significantly decreasing inflammatory cells (Z-score, 5.60) and enhancing fibroblast distribution (Z-score, 5.98), epithelialization (Z-score, 8.57), collagen production (Z-score, 4.20), and angiogenesis factors of MVD (Z-score, 5.66) and VEGF (Z-score, 3.86). Furthermore, quercetin significantly inhibited tyrosinase activity (Z-score, 1.95), resulting in a significantly reduced melanin content (Z-score, 2.56). A significant reduction in DNA damage (Z-score, 3.27), melanoma cell viability (Z-score, 2.97), and tumor formation was also observed to ensure the promising activity of quercetin for skin issues. This review highlights quercetin's potential as a multifaceted agent in skin care and treatment.

Generation of human expandable limb-bud-like progenitors via chemically induced dedifferentiation

In certain highly regenerative animals, cellular dedifferentiation occurs after injury, allowing specialized cells to become progenitor cells for regeneration. However, this capacity is restricted in human cells due to reduced plasticity. Here, we introduce a chemical-induced dedifferentiation approach that reverts the differentiated cells to a progenitor-like state, conferring the features of human limb bud cells from human adult somatic cells. These chemically induced human limb-bud-like progenitors (hCiLBP cells) show a high degree of transcriptomic similarity to human embryonic limb bud progenitors. Importantly, we established culture conditions that allow hCiLBP cells to undergo extensive expansion while maintaining population homogeneity and long-term self-renewal capacity. Moreover, hCiLBP cells exhibit increased osteochondrogenic differentiation ability, providing an innovative platform for generation of skeletal lineage cell types. These results highlight a potential therapeutic approach for repairing damaged human tissues through reversal of developmental pathways from mature cells to expandable progenitor cells.

TPR is required for cytoplasmic chromatin fragment formation during senescence

During oncogene-induced senescence there are striking changes in the organisation of heterochromatin in the nucleus. This is accompanied by activation of a pro-inflammatory gene expression programme - the senescence-associated secretory phenotype (SASP) - driven by transcription factors such as NF-κB. The relationship between heterochromatin re-organisation and the SASP has been unclear. Here, we show that TPR, a protein of the nuclear pore complex basket required for heterochromatin re-organisation during senescence, is also required for the very early activation of NF-κB signalling during the stress-response phase of oncogene-induced senescence. This is prior to activation of the SASP and occurs without affecting NF-κB nuclear import. We show that TPR is required for the activation of innate immune signalling at these early stages of senescence and we link this to the formation of heterochromatin-enriched cytoplasmic chromatin fragments thought to bleb off from the nuclear periphery. We show that HMGA1 is also required for cytoplasmic chromatin fragment formation. Together these data suggest that re-organisation of heterochromatin is involved in altered structural integrity of the nuclear periphery during senescence, and that this can lead to activation of cytoplasmic nucleic acid sensing, NF-κB signalling, and activation of the SASP.

Roles of the lamin A-specific tail region in the localization to sites of nuclear envelope rupture

The nuclear lamina (NL) lines the nuclear envelope (NE) to maintain nuclear structure in metazoan cells. The major NL components, the nuclear lamins contribute to the protection against NE rupture induced by mechanical stress. Lamin A (LA) and a short form of the splicing variant lamin C (LC) are diffused from the nucleoplasm to sites of NE rupture in immortalized mouse embryonic fibroblasts (MEFs). LA localization to the rupture sites is significantly slow and weak compared with LC, but the underlying mechanism remains unknown. In this study, wild-type (WT), Hutchinson-Gilford Progeria syndrome (HGPS) knock-in MEFs expressing progerin (PG, an LA mutant lacking the second proteolytic cleavage site), and LA/C-knockout MEFs transiently and heterogeneously expressing LA/C WTs and mutants fused to mEmerald are examined before and after NE rupture induced by single-cell compression and laser microirradiation. The farnesylation at the CaaX motif of unprocessed LA and the inhibition of the second proteolytic cleavage decrease the nucleoplasmic pool and slow the localization to the rupture sites in a long-time window (60-70 min) after the induction of NE rupture. Our data could explain the defective repair of NE rupture in HGPS through the farnesylation at the CaaX motif of unprocessed progerin. In addition, unique segments in LA-specific tail region cooperate with each other to inhibit the rapid accumulation within a short-time window (3 min) that is also observed with LC.

Marizomib Promotes Senescence or Long-Term Apoptosis in Melanoma Cancer Cells

Cellular senescence is cell cycle arrest and the inhibition of cell proliferation. New anticancer approaches include the elimination of cancer cells through the induction of senescence followed by senolysis. New prosenescence compounds are still being searched for. Little is known about the ability of proteasome inhibitors to induce senescence in tumor cells, especially in malignant melanoma. The aim of our study was to verify the activity of a natural proteasome inhibitor-marizomib (MZB)-directly after incubation and after its removal to assess its potential to induce senescence or long-term apoptosis in malignant melanoma cell lines (A375 and G361). After 48 h of incubation with MZB, we observed an increased number of SA-β-galactosidase-positive cells, upregulated expression of P21 and P-P53 proteins and an increased number of cells at the subG1 phase (line G361) or at both the subG1 and G2/M phases (line A375). After 96 h from inhibitor removal, the G361 line presented signs of senescence (increased level of SA-β-galactosidase, IL-8, P-P53, G2/M and S phases of cell cycle, decreased lamin B1 and cleaved lamin B1), while the A375 line demonstrated more signs of apoptosis (increased subG1 phase, P-P53, cleaved lamin B1). The gathered findings suggest that MZB resulted in the induction of cellular senescence (line G361) or enhanced apoptosis (line A375) in the melanoma cell lines tested here and could be a promising therapeutic factor in malignant melanoma treatment.

Disorganized chromatin hierarchy and stem cell aging in a male patient of atypical laminopathy-based progeria mandibuloacral dysplasia type A

Studies of laminopathy-based progeria offer insights into aging-associated diseases and highlight the role of LMNA in chromatin organization. Mandibuloacral dysplasia type A (MAD) is a largely unexplored form of atypical progeria that lacks lamin A post-translational processing defects. Using iPSCs derived from a male MAD patient carrying homozygous LMNA p.R527C, premature aging phenotypes are recapitulated in multiple mesenchymal lineages, including mesenchymal stem cells (MSCs). Comparison with 26 human aging MSC expression datasets reveals that MAD-MSCs exhibit the highest similarity to senescent primary human MSCs. Lamina-chromatin interaction analysis reveals reorganization of lamina-associating domains (LADs) and repositioning of non-LAD binding peaks may contribute to the observed accelerated senescence. Additionally, 3D genome organization further supports hierarchical chromatin disorganization in MAD stem cells, alongside dysregulation of genes involved in epigenetic modification, stem cell fate maintenance, senescence, and geroprotection. Together, these findings suggest LMNA missense mutation is linked to chromatin alterations in an atypical progeroid syndrome.

Effect of senolytic drugs in young female mice chemically induced to estropause

AIMS

This study aimed to assess metabolic responses and senescent cell burden in young female mice induced to estropause and treated with senolytic drugs.

MAIN METHODS

Estropause was induced by 4-vinylcyclohexene diepoxide (VCD) injection in two-month-old mice. The senolytics dasatinib and quercetin (D + Q) or fisetin were given by oral gavage once a month from five to 11 months of age.

KEY FINDINGS

VCD-induced estropause led to increased body mass and reduced albumin concentrations compared to untreated cyclic mice, without affecting insulin sensitivity, lipid profile, liver enzymes, or total proteins. Estropause decreased catalase activity in adipose tissue but had no significant effect on other redox parameters in adipose and hepatic tissues. Fisetin treatment reduced ROS levels in the hepatic tissue of estropause mice. Estropause did not influence senescence-associated beta-galactosidase activity in adipose and hepatic tissues but increased senescent cell markers and fibrosis in ovaries. Senolytic treatment did not decrease ovarian cellular senescence induced by estropause.

SIGNIFICANCE

Overall, the findings suggest that estropause leads to minor metabolic changes in young females, and the senolytics D + Q and fisetin had no protective effects despite increased ovarian senescence.

Mitochondrial fatty acid oxidation drives senescence

Cellular senescence is a stress-induced irreversible cell cycle arrest involved in tumor suppression and aging. Many stresses, such as telomere shortening and oncogene activation, induce senescence by damaging nuclear DNA. However, the mechanisms linking DNA damage to senescence remain unclear. Here, we show that DNA damage response (DDR) signaling to mitochondria triggers senescence. A genome-wide small interfering RNA screen implicated the outer mitochondrial transmembrane protein BNIP3 in senescence induction. We found that BNIP3 is phosphorylated by the DDR kinase ataxia telangiectasia mutated (ATM) and contributes to an increase in the number of mitochondrial cristae. Stable isotope labeling metabolomics indicated that the increase in cristae enhances fatty acid oxidation (FAO) to acetyl-coenzyme A (acetyl-CoA). This promotes histone acetylation and expression of the cyclin-dependent kinase inhibitor p16INK4a. Notably, pharmacological activation of FAO alone induced senescence both in vitro and in vivo. Thus, mitochondrial energy metabolism plays a critical role in senescence induction and is a potential intervention target to control senescence.

Werner syndrome RECQ helicase participates in and directs maintenance of the protein complexes of constitutive heterochromatin in proliferating human cells

Werner syndrome of premature aging is caused by mutations in the WRN RECQ helicase/exonuclease, which functions in DNA replication, repair, transcription, and telomere maintenance. How the loss of WRN accelerates aging is not understood in full. Here we show that WRN is necessary for optimal constitutive heterochromatin levels in proliferating human fibroblasts. Locally, WRN deficiency derepresses SATII pericentromeric satellite repeats but does not reduce replication fork progression on SATII repeats. Globally, WRN loss reduces a subset of protein-protein interactions responsible for the organization of constitutive heterochromatin in the nucleus, namely, the interactions involving Lamin B1 and Lamin B receptor, LBR. Both the mRNA level and subcellular distribution of LBR are affected by WRN deficiency, and unlike the former, the latter phenotype does not require WRN catalytic activities. The phenotypes of heterochromatin disruption seen in WRN-deficient proliferating fibroblasts are also observed in WRN-proficient fibroblasts undergoing replicative or oncogene-induced senescence. WRN interacts with histone deacetylase 2, HDAC2; WRN/HDAC2 association is mediated by heterochromatin protein alpha, HP1α, and WRN complexes with HP1α and HDAC2 are downregulated in senescing cells. The data suggest that the effect of WRN loss on heterochromatin is separable from senescence program, but mimics at least some of the heterochromatin changes associated with it.

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.

Pharmacological targeting of P300/CBP reveals EWS::FLI1-mediated senescence evasion in Ewing sarcoma

Ewing sarcoma (ES) poses a significant therapeutic challenge due to the difficulty in targeting its main oncodriver, EWS::FLI1. We show that pharmacological targeting of the EWS::FLI1 transcriptional complex via inhibition of P300/CBP drives a global transcriptional outcome similar to direct knockdown of EWS::FLI1, and furthermore yields prognostic risk factors for ES patient outcome. We find that EWS::FLI1 upregulates LMNB1 via repetitive GGAA motif recognition and acetylation codes in ES cells and EWS::FLI1-permissive mesenchymal stem cells, which when reversed by P300 inhibition leads to senescence of ES cells. P300-inhibited senescent ES cells can then be eliminated by senolytics targeting the PI3K signaling pathway. The vulnerability of ES cells to this combination therapy suggests an appealing synergistic strategy for future therapeutic exploration.

Heparan Sulfate-Collagen Surface Multilayers Support Serum-Free Microcarrier Culture of Mesenchymal Stem Cells

The increasing cost of high-volume cultures and dependence on serum and growth factor supplementation limit the affordability of mesenchymal stromal cell (MSC) therapies. This has spurred interest in developing strategies that support adherent cell expansion while reducing raw material costs. Culture surfaces coated with sulfated glycosaminoglycans (GAGs), specifically heparan sulfate (HS), are an alternative to prolong growth factor retention in cell cultures. Unlike heparin, recombinant HS (rHS) offers strong binding affinity for multiple growth factors and extracellular matrix components, such as collagen I, without undesirable anticoagulant effects or xenobiotic health risks. The potential of rHS as a factor reservoir in MSC cultures remains underexplored. This study investigated the impact of rHS on the growth and anti-inflammatory properties of undifferentiated bone marrow MSCs in both planar and microcarrier-based cultures. It was hypothesized that rHS would enable MSC growth with minimal growth factor supplementation in a sulfation level-dependent manner. Cell culture surfaces were assembled via the layer-by-layer (LbL) method, combining alternating collagen I (COL) and rHS. These bilayers support cell adhesion and enable the incorporation of distinct sulfation levels on the culture surface. Examination of pro-mitogenic FGF and immunostimulatory IFN-γ release dynamics confirmed prolonged availability and sulfate level dependencies. Sulfated surfaces supported cell growth in low serum (2% FBS) and serum-free (SF) media at levels equivalent to standard culture conditions. Cell growth on rHS-coated surfaces in SF was comparable to that on heparin-coated surfaces and commercial surface-coated microcarriers in low serum. These growth benefits were observed in both planar and microcarrier (μCs) cultures. Additionally, rHS surfaces reduced β-galactosidase expression relative to uncoated surfaces, delaying cell senescence. Multivariate analysis of cytokines in conditioned media indicated that rHS-containing surfaces enhanced cytokine levels relative to uncoated surfaces during IFN-γ stimulation and correlated with decreased pro-inflammatory macrophage activity. Overall, utilizing highly sulfated rHS with COL reduces the need for exogenous growth factors and effectively supports MSC growth and anti-inflammatory potency on planar and microcarrier surfaces under minimal factor supplementation.

YIPF2 regulates genome integrity

Understanding of the mechanisms for genome integrity maintenance can help in developing effective intervention strategies to combat aging. A whole-genome RNAi screen was conducted to identify novel factors involved in maintaining genome stability. The potential target genes identified in the screening are related to the cell cycle, proteasome, and spliceosomes. Unexpectedly, the Golgi protein YIPF2 has been found to play a critical role in maintaining genome stability. The depletion of YIPF2 hinders the process of homologous recombination (HR) repair, which then triggers DNA damage response mechanisms, ultimately leading to cellular senescence. The overexpression of YIPF2 facilitated cellular recovery from DNA damage induced by chemotherapy agents or replicative senescence-associated DNA damage. Our findings indicate that only the intact Golgi apparatus containing YIPF2 provides a protective effect on genome integrity.

LINE-1 transposable element renaissance in aging and age-related diseases

Transposable elements (TEs) are essential components of eukaryotic genomes and subject to stringent regulatory mechanisms to avoid their potentially deleterious effects. However, numerous studies have verified the resurrection of TEs, particularly long interspersed nuclear element-1 (LINE-1), during preimplantation development, aging, cancer, and other age-related diseases. The LINE-1 family has also been implicated in several aging-related processes, including genomic instability, loss of heterochromatin, DNA methylation, and the senescence-associated secretory phenotype (SASP). Additionally, the role of the LINE-1 family in cancer development has also been substantiated. Research in this field has offered valuable insights into the functional mechanisms underlying LINE-1 activity, enhancing our understanding of aging regulation. This review provides a comprehensive summary of current findings on LINE-1 and their roles in aging and age-related diseases.

PQBP3 prevents senescence by suppressing PSME3-mediated proteasomal Lamin B1 degradation

Senescence of nondividing neurons remains an immature concept, with especially the regulatory molecular mechanisms of senescence-like phenotypes and the role of proteins associated with neurodegenerative diseases in triggering neuronal senescence remaining poorly explored. In this study, we reveal that the nucleolar polyglutamine binding protein 3 (PQBP3; also termed NOL7), which has been linked to polyQ neurodegenerative diseases, regulates senescence as a gatekeeper of cytoplasmic DNA leakage. PQBP3 directly binds PSME3 (proteasome activator complex subunit 3), a subunit of the 11S proteasome regulator complex, decreasing PSME3 interaction with Lamin B1 and thereby preventing Lamin B1 degradation and senescence. Depletion of endogenous PQBP3 causes nuclear membrane instability and release of genomic DNA from the nucleus to the cytosol. Among multiple tested polyQ proteins, ataxin-1 (ATXN1) partially sequesters PQBP3 to inclusion bodies, reducing nucleolar PQBP3 levels. Consistently, knock-in mice expressing mutant Atxn1 exhibit decreased nuclear PQBP3 and a senescence phenotype in Purkinje cells of the cerebellum. Collectively, these results suggest homologous roles of the nucleolar protein PQBP3 in cellular senescence and neurodegeneration.

Proteome-wide 4-hydroxy-2-nonenal signature of oxidative stress in the marine invasive tunicate Botryllus schlosseri

The colonial ascidian Boytryllus schlosseri is an invasive marine chordate that thrives under conditions of anthropogenic climate change. We show that the B. schlosseri expressed proteome contains unusually high levels of proteins that are adducted with 4-hydroxy-2-nonenal (HNE). HNE represents a prominent posttranslational modification resulting from oxidative stress. Although numerous studies have assessed oxidative stress in marine organisms HNE protein modification has not previously been determined in any marine species. LC/MS proteomics was used to identify 1052 HNE adducted proteins in B. schlosseri field and laboratory populations. Adducted amino acid residues were ascertained for 1849 modified sites, of which 1195 had a maximum amino acid localization score. Most HNE modifications were at less reactive lysines (rather than more reactive cysteines). HNE prevelance on most sites was high. These observations suggest that B. schlosseri experiences and tolerates high intracellular reactive oxygen species levels, resulting in substantial lipid peroxidation. HNE adducted B. schlosseri proteins show enrichment in mitochondrial, proteostasis, and cytoskeletal functions. Based on these results we propose that redox signaling contributes to regulating energy metabolism, the blastogenic cycle, oxidative burst defenses, and cytoskeleton dynamics during B. schlosseri development and physiology. A DIA assay library was constructed to quantify HNE adduction at 72 sites across 60 proteins that represent a holistic network of functionally discernable oxidative stress bioindicators. We conclude that the vast amount of HNE protein adduction in this circumpolar tunicate is indicative of high oxidative stress tolerance contributing to its range expansion into diverse environments.

NEW & NOTEWORTHY

Oxidative stress results from environmental challenges that increase in frequency and severity during the Anthropocene. Oxygen radical attack causes lipid peroxidation leading to HNE production. Proteome-wide HNE adduction is highly prevalent in Botryllus schlosseri , a widely distributed, highly invasive, and economically important biofouling ascidian and the first marine species to be analyzed for proteome HNE modification. HNE adduction of specific proteins physiologically sequesters reactive oxygen species, which enhances fitness and resilience during environmental change.

BACH1 inhibits senescence, obesity, and short lifespan by ferroptotic FGF21 secretion

Ferroptosis is a type of regulated cell death characterized by iron-dependent lipid peroxidation. A model cell system is constructed to induce ferroptosis by re-expressing the transcription factor BACH1, a potent ferroptosis inducer, in immortalized mouse embryonic fibroblasts (iMEFs). The transfer of the culture supernatant from ferroptotic iMEFs activates the proliferation of hepatoma cells and other fibroblasts and suppresses cellular senescence-like features. The BACH1-dependent secretion of the longevity factor FGF21 is increased in ferroptotic iMEFs. The anti-senescent effects of the culture supernatant from these iMEFs are abrogated by Fgf21 knockout. BACH1 activates the transcription of Fgf21 by promoting ferroptotic stress and increases FGF21 protein expression by suppressing its autophagic degradation through transcriptional Sqstm1 and Lamp2 repression. The BACH1-induced ferroptotic FGF21 secretion suppresses obesity in high-fat diet-fed mice and the short lifespan of progeria mice. The inhibition of these aging-related phenotypes can be physiologically significant regarding ferroptosis.

Comparative biological activity of palbociclib and ribociclib in hormone receptor-positive breast cancer

This study examines the biological effects of palbociclib and ribociclib in hormone receptor-positive breast cancer, pivotal to the HARMONIA prospective phase III clinical trial. We explore the downstream impacts of these CDK4/6 inhibitors, focusing on cell lines and patient-derived tumor samples. We treated HR+ breast cancer cell lines (T47D, MCF7, and BT474) with palbociclib or ribociclib (100 nM or 500 nM), alone or combined with fulvestrant (1 nM), over periods of 24, 72, or 144 h. Our assessments included PAM50 gene expression, RB1 phosphorylation, Lamin-B1 protein levels, and senescence-associated β-galactosidase activity. We further analyzed PAM50 gene signatures from the CORALLEEN and NeoPalAna phase II trials. Both CDK4/6 inhibitors similarly inhibited proliferation across the cell lines. At 100 nM, both drugs partially reduced p-RB1, with further decreases at 500 nM over 144 h. Treatment led to reduced Lamin-B1 expression and increased senescence-associated β-galactosidase activity. Both drugs enhanced Luminal A and reduced Luminal B and proliferation signatures at both doses. However, the HER2-enriched signature significantly diminished only at the higher dose of 500 nM. Corresponding changes were observed in tumor samples from the CORALLEEN and NeoPalAna studies. At 2 weeks of treatment, both drugs significantly reduced the HER2-enriched signature, but at surgery, this reduction was consistent only with ribociclib. Our findings suggest that while both CDK4/6 inhibitors effectively modulate key biological pathways in HR+/HER2- breast cancer, nuances in their impact, particularly on the HER2-enriched signature, are dose-dependent, influenced by the addition of fulvestrant and warrant further investigation.

Platycodi radix aqueous extract salvages doxorubicin-induced senescence by mitochondrial reactive oxygen species reduction in umbilical cord matrix stem cells

Platycodi radix is a widely used herbal medicine that contains numerous phytochemicals beneficial to health. The health and biological benefits of P. radix have been found across various diseases. The utilization of umbilical cord stromal stem cells, derived from Wharton's jelly of the human umbilical cord, has emerged as a promising approach for treating degenerative diseases. Nevertheless, growing evidence indicates that the function of stem cells declines with age, thereby limiting their regenerative capacity. The primary objective in this study is to investigate the beneficial effects of P. radix in senescent stem cells. We conducted experiments to showcase that diminished levels of Lamin B1 and Sox-2, along with an elevation in p21, which serve as indicative markers for the senescent stem cells. Our findings revealed the loss of Lamin B1 and Sox-2, coupled with an increase in p21, in umbilical cord stromal stem cells subjected to a low-dose (0.1 μM) doxorubicin (Dox) stimulation. However, P. radix restored the Dox-damage in the umbilical cord stromal stem cells. P. radix reversed the senescent conditions when the umbilical cord stromal stem cells exposed to Dox-induced reactive oxygen species (ROS) and mitochondrial membrane potential are significantly changed. In Dox-challenged aged umbilical cord stromal stem cells, P. radix reduced senescence, increased longevity, prevented mitochondrial dysfunction and ROS and protected against senescence-associated apoptosis. This study suggests that P. radix might be as a therapeutic and rescue agent for the aging effect in stem cells. Inhibition of cell death, mitochondrial dysfunction and aging-associated ROS with P. radix provides additional insights into the underlying molecular mechanisms.

Replicative senescence is ATM driven, reversible, and accelerated by hyperactivation of ATM at normoxia

Programmed telomere shortening limits tumorigenesis through the induction of replicative senescence. Here we address three long-standing questions concerning senescence. First, we show that the ATM kinase is solely responsible for the induction of replicative senescence. Senescence was delayed by ATM inhibition (ATMi) or overexpression of TRF2, the shelterin subunit dedicated to ATM repression. In contrast, there was no evidence for ATR signaling contributing to replicative senescence even when ATMi was combined with ATR inhibition. Second, we show ATMi can induce apparently normal cell divisions in a subset of senescent cells, indicating that senescence can be reversed. Third, we show that the extended replicative life span at low (physiological) oxygen is due to diminished ATM activity. At low oxygen, cells show a decreased ATM response to dysfunctional telomeres and genome-wide DSBs compared to 20% oxygen. As this effect could be reversed by NAC, the attenuated response of ATM to critically short telomeres and the resulting extended life span at low oxygen is likely due to ROS-induced formation of cysteine disulfide-bridges that crosslink ATM dimers into a form that is not activated by DSBs. These findings show how primary human cells detect shortened telomeres and reveal the molecular mechanism underlying the telomere tumor suppressor pathway.

Cellular Senescence in Acute Liver Injury: What Happens to the Young Liver?

Cellular senescence, characterized by irreversible cell cycle arrest, not only exists in age-related physiological states, but has been found to exist in various diseases. It plays a crucial role in both physiological and pathological processes and has become a trending topic in global research in recent years. Acute liver injury (ALI) has a high incidence worldwide, and recent studies have shown that hepatic senescence can be induced following ALI. Therefore, we reviewed the significance of cellular senescence in ALI. To minimize the potential confounding effects of aging on cellular senescence and ALI outcomes, we selected studies involving young individuals to identify the characteristics of senescent cells, the value of cellular senescence in liver repair, its regulation mechanisms in ALI, its potential as a biomarker for ALI, the prospect of treatment, and future research directions.

Effects of immune exhaustion and senescence of innate immunity in autoimmune disorders

Innate immune system activation is crucial in the inflammatory response, but uncontrolled activation can lead to autoimmune diseases. Cellular exhaustion and senescence are two processes that contribute to innate immune tolerance breakdown. Exhausted immune cells are unable to respond adequately to specific antigens or stimuli, while senescent cells have impaired DNA replication and metabolic changes. These processes can impair immune system function and disrupt homeostasis, leading to the emergence of autoimmunity. However, the influence of innate immune exhaustion and senescence on autoimmune disorders is not well understood. This review aims to describe the current findings on the role of innate immune exhaustion and senescence in autoimmunity, focusing on the cellular and molecular changes involved in each process. Specifically, the article explores the markers and pathways associated with immune exhaustion, such as PD-1 and TIM-3, and senescence, including Β-galactosidase (β-GAL), lamin B1, and p16ink4a, and their impact on autoimmune diseases, namely type 1 diabetes, rheumatoid arthritis, systemic lupus erythematosus, and immune-mediated myopathies. Understanding the mechanisms underlying innate immune exhaustion and senescence in autoimmunity may provide insights for the development of novel therapeutic strategies.

In silico study to explore the mechanism of Toxoplasma-induced inflammation and target therapy based on sero and salivary Toxoplasma

We aimed to assess salivary and seroprevalence of Toxoplasma immunoglobulins in risky populations and evaluate drug docking targeting TgERP. A cross-sectional study was conducted in Alexandria University hospitals' outpatient clinics. 192 participants were enrolled from September 2022 to November 2023. Anti-Toxoplasma IgG and IgM were determined in serum and saliva by ELISA. An in-Silico study examined TgERP's protein-protein interactions (PPIs) with pro-inflammatory cytokine receptors, anti-inflammatory cytokine, cell cycle progression regulatory proteins, a proliferation marker, and nuclear envelope integrity-related protein Lamin B1. Our findings revealed that anti-T. gondii IgG were detected in serum (66.1%) and saliva (54.7%), with 2.1% of both samples were positive for IgM. Salivary IgG had 75.59% sensitivity, 86.15% specificity, 91.40% PPV, 64.40% NPP, 79.17% accuracy and fair agreement with serum IgG. On the other hand, the sensitivity, specificity, PPV, NPV, and accuracy in detecting salivary IgM were 75.0%, 99.47%, 75.0%, 99.47%, and 98.96%. AUC 0.859 indicates good discriminatory power. Examined synthetic drugs and natural products can target specific amino acids residues of TgERP that lie at the same binding interface with LB1 and Ki67, subsequently, hindering their interaction. Hence, salivary samples can be a promising diagnostic approach. The studied drugs can counteract the pro-inflammatory action of TgERP.

EZH2 inhibition induces senescence via ERK1/2 signaling pathway in multiple myeloma

Epigenetic modifications play an important role in cellular senescence, and enhancer of zeste homolog 2 (EZH2) is a key methyltransferase involved in epigenetic remodeling in multiple myeloma (MM) cells. We have previously demonstrated that GSK126, a specific EZH2 inhibitor, exhibits anti-MM therapeutic efficacy and safety in vivo and in vitro; however, its specific mechanism remains unclear. This study shows that GSK126 induces cellular senescence in MM, which is characterized by the accumulation of senescence-associated heterochromatin foci (SAHF) and p21, and increased senescence-associated β galactosidase activity. Furthermore, EZH2 is inhibited in ribonucleotide reductase regulatory subunit M2 (RRM2)-overexpressing OCI-MY5 and RPMI-8226 cells. RRM2 overexpression inhibits the methyltransferase function of EZH2 and promotes its degradation through the ubiquitin-proteasome pathway, thereby inducing cellular senescence. In this senescence model, Lamin B1, a key component of the nuclear envelope and a marker of senescence, does not decrease but instead undergoes aberrant accumulation. Meanwhile, phosphorylation of extracellular signal-regulated protein kinase (ERK1/2) is significantly increased. The inhibition of ERK1/2 phosphorylation in turn partially restores Lamin B1 level and alleviates senescence. These findings suggest that EZH2 inhibition increases Lamin B1 level and induces senescence by promoting ERK1/2 phosphorylation. These data indicate that EZH2 plays an important role in MM cellular senescence and provide insights into the relationships among Lamin B1, p-ERK1/2, and cellular senescence.

Tumor biomarkers for diagnosis, prognosis and targeted therapy

Tumor biomarkers, the substances which are produced by tumors or the body's responses to tumors during tumorigenesis and progression, have been demonstrated to possess critical and encouraging value in screening and early diagnosis, prognosis prediction, recurrence detection, and therapeutic efficacy monitoring of cancers. Over the past decades, continuous progress has been made in exploring and discovering novel, sensitive, specific, and accurate tumor biomarkers, which has significantly promoted personalized medicine and improved the outcomes of cancer patients, especially advances in molecular biology technologies developed for the detection of tumor biomarkers. Herein, we summarize the discovery and development of tumor biomarkers, including the history of tumor biomarkers, the conventional and innovative technologies used for biomarker discovery and detection, the classification of tumor biomarkers based on tissue origins, and the application of tumor biomarkers in clinical cancer management. In particular, we highlight the recent advancements in biomarker-based anticancer-targeted therapies which are emerging as breakthroughs and promising cancer therapeutic strategies. We also discuss limitations and challenges that need to be addressed and provide insights and perspectives to turn challenges into opportunities in this field. Collectively, the discovery and application of multiple tumor biomarkers emphasized in this review may provide guidance on improved precision medicine, broaden horizons in future research directions, and expedite the clinical classification of cancer patients according to their molecular biomarkers rather than organs of origin.

Upregulated expression of lamin B receptor increases cell proliferation and suppresses genomic instability: implications for cellular immortalization

Mammalian somatic cells undergo terminal proliferation arrest after a limited number of cell divisions, a phenomenon termed cellular senescence. However, cells acquire the ability to proliferate infinitely (cellular immortalization) through multiple genetic alterations. Inactivation of tumor suppressor genes such as p53, RB and p16 is important for cellular immortalization, although additional molecular alterations are required for cellular immortalization to occur. Here, we aimed to gain insights into these molecular alterations. Given that cellular immortalization is the escape of cells from cellular senescence, genes that regulate cellular senescence are likely to be involved in cellular immortalization. Because senescent cells show altered heterochromatin organization, we investigated the implications of lamin A/C, lamin B1 and lamin B receptor (LBR), which regulate heterochromatin organization, in cellular immortalization. We employed human immortalized cell lines, KMST-6 and SUSM-1, and found that expression of LBR was upregulated upon cellular immortalization and downregulated upon cellular senescence. In addition, knockdown of LBR induced cellular senescence with altered chromatin configuration. Additionally, enforced expression of LBR increased cell proliferation likely through suppression of genome instability in human primary fibroblasts that expressed the simian virus 40 large T antigen (TAg), which inactivates p53 and RB. Furthermore, expression of TAg or knockdown of p53 led to upregulated LBR expression. These observations suggested that expression of LBR might be upregulated to suppress genome instability in TAg-expressing cells, and, consequently, its upregulated expression assisted the proliferation of TAg-expressing cells (i.e. p53/RB-defective cells). Our findings suggest a crucial role for LBR in the process of cellular immortalization.

Therapeutic strategies targeting cellular senescence for cancer and other diseases

Cellular senescence occurs in response to endogenous or exogenous stresses and is characterized by stable cell cycle arrest, alterations in nuclear morphology and secretion of proinflammatory factors, referred to as the senescence-associated secretory phenotype (SASP). An increase of senescent cells is associated with the development of several types of cancer and aging-related diseases. Therefore, senolytic agents that selectively remove senescent cells may offer opportunities for developing new therapeutic strategies against such cancers and aging-related diseases. This review outlines senescence inducers and the general characteristics of senescent cells. We also discuss the involvement of senescent cells in certain cancers and diseases. Finally, we describe a series of senolytic agents and their utilization in therapeutic strategies.

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.

Fusobacterium nucleatum triggers senescence phenotype in gingival epithelial cells

The prevalence of periodontitis increases with physiological aging. However, whether bacteria associated with periodontal diseases foster aging and the mechanisms by which they may do so are unknown. Herein, we hypothesize that Fusobacterium nucleatum, a microorganism associated with periodontitis and several other age-related disorders, triggers senescence, a chief hallmark of aging responsible to reduce tissue repair capacity. Our study analyzed the senescence response of gingival epithelial cells and their reparative capacity upon long-term exposure to F. nucleatum. Specifically, we assessed (a) cell cycle arrest by analyzing the cyclin-dependent kinase inhibitors p16INK4a and p14ARF and their downstream cascade (pRb, p53, and p21) at both gene and protein levels, (b) lysosomal mediated dysfunction by using assays targeting the expression and activity of the senescence-associated β-galactosidase (SA-β-Gal) enzyme, and (c) nuclear envelope breakdown by assessing the expression of Lamin-B1. The consequences of the senescence phenotype mediated by F. nucleatum were further assessed using wound healing assays. Our results revealed that prolonged exposure to F. nucleatum promotes an aging-like phenotype as evidenced by the increased expression of pro-senescence markers (p16INK4a , p21, and pRb) and SA-β-Gal activity and reduced expression of the counter-balancing cascade (p14ARF and p53) and Lamin-B1. Furthermore, we also noted impaired wound healing capacity of gingival epithelial cells upon prolong bacterial exposure, which was consistent with the senescence-induced phenotype. Together, our findings provide a proof-of-concept evidence that F. nucleatum triggers a pro-senescence response in gingival epithelial cells. This might affect periodontal tissue homeostasis by reducing its repair capacity and, consequently, increasing susceptibility to periodontitis during aging.

Micronucleus is not a potent inducer of the cGAS/STING pathway

Micronuclei (MN) have been associated with the innate immune response. The abrupt rupture of MN membranes results in the accumulation of cGAS, potentially activating STING and downstream interferon-responsive genes. However, direct evidence connecting MN and cGAS activation has been lacking. We have developed the FuVis2 reporter system, which enables the visualization of the cell nucleus carrying a single sister chromatid fusion and, consequently, MN. Using this FuVis2 reporter equipped with cGAS and STING reporters, we rigorously assessed the potency of cGAS activation by MN in individual living cells. Our findings reveal that cGAS localization to membrane-ruptured MN during interphase is infrequent, with cGAS primarily capturing MN during mitosis and remaining bound to cytosolic chromatin. We found that cGAS accumulation during mitosis neither activates STING in the subsequent interphase nor triggers the interferon response. Gamma-ray irradiation activates STING independently of MN formation and cGAS localization to MN. These results suggest that cGAS accumulation in cytosolic MN is not a robust indicator of its activation and that MN are not the primary trigger of the cGAS/STING pathway.

Protective Effect of Curcumin on D-Galactose-Induced Senescence and Oxidative Stress in LLC-PK1 and HK-2 Cells

D-galactose has been widely used as an inducer of cellular senescence and pathophysiological processes related to aging because it induces oxidative stress. On the other hand, the consumption of antioxidants such as curcumin can be an effective strategy to prevent phenotypes related to the enhanced production of reactive oxygen species (ROS), such as aging and senescence. This study aimed to evaluate the potential protective effect of curcumin on senescence and oxidative stress and endoplasmic reticulum stress induced by D-galactose treatment in Lilly Laboratories Culture-Porcine Kidney 1 (LLC-PK1) and human kidney 2 (HK-2) proximal tubule cell lines from pig and human, respectively. For senescence induction, cells were treated with 300 mM D-galactose for 120 h and, to evaluate the protective effect of the antioxidant, cells were treated with 5 µM curcumin for 24 h and subsequently treated with curcumin + D-galactose for 120 h. In LLC-PK1 cells, curcumin treatment decreased by 20% the number of cells positive for senescence-associated (SA)-β-D-galactosidase staining and by 25% the expression of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and increased by 40% lamin B1 expression. In HK-2 cells, curcumin treatment increased by 60% the expression of proliferating cell nuclear antigen (PCNA, 50% Klotho levels, and 175% catalase activity. In both cell lines, this antioxidant decreased the production of ROS (20% decrease for LLC-PK1 and 10 to 20% for HK-2). These data suggest that curcumin treatment has a moderate protective effect on D-galactose-induced senescence in LLC-PK1 and HK-2 cells.

Serine Metabolism Regulates the Replicative Senescence of Human Dental Pulp Cells through Histone Methylation

Tissue regeneration therapy based on human dental pulp cells (hDPCs) faces the distinct challenge of cellular senescence during massive expansion in vitro. To further explore the regulatory mechanism of cellular senescence in hDPCs, we conduct experiments on young cells (Passage 5, P5) and replicative senescent (Passage 12, P12) hDPCs. The results confirm that hDPCs undergo replicative senescence with passaging, during which their ability to proliferate and osteogenic differentiation decreases. Notably, during replicative senescence, phosphoglycerate dehydrogenase (PHGDH), the key enzyme of the serine synthesis pathway (SSP), is significantly downregulated, as well as S-adenosylmethionine (SAM) levels, resulting in reduced H3K36me3 modification on Sirtuin 1 (SIRT1)and Runt-related transcription factor 2 (RUNX2) promoters. Inhibition of PHGDH leads to the same phenotype as replicative senescence. Serine supplementation fails to rescue the senescence phenotype caused by replicative senescence and inhibitors, in which folate metabolism-related genes, including serine hydroxymethyl transferase 2 (SHMT2), methylenetetrahydrofolate dehydrogenase 1(MTHFD1), methylenetetrahydrofolate dehydrogenase 2(MTHFD2), are notably decreased. Our research raised a possibility that PHGDH may be involved in cellular senescence by affecting folate metabolism and histone methylation in addition to serine biosynthesis, providing potential targets to prevent senescence.

Depletion of lamins B1 and B2 promotes chromatin mobility and induces differential gene expression by a mesoscale-motion-dependent mechanism

BACKGROUND

B-type lamins are critical nuclear envelope proteins that interact with the three-dimensional genomic architecture. However, identifying the direct roles of B-lamins on dynamic genome organization has been challenging as their joint depletion severely impacts cell viability. To overcome this, we engineered mammalian cells to rapidly and completely degrade endogenous B-type lamins using Auxin-inducible degron technology.

RESULTS

Using live-cell Dual Partial Wave Spectroscopic (Dual-PWS) microscopy, Stochastic Optical Reconstruction Microscopy (STORM), in situ Hi-C, CRISPR-Sirius, and fluorescence in situ hybridization (FISH), we demonstrate that lamin B1 and lamin B2 are critical structural components of the nuclear periphery that create a repressive compartment for peripheral-associated genes. Lamin B1 and lamin B2 depletion minimally alters higher-order chromatin folding but disrupts cell morphology, significantly increases chromatin mobility, redistributes both constitutive and facultative heterochromatin, and induces differential gene expression both within and near lamin-associated domain (LAD) boundaries. Critically, we demonstrate that chromatin territories expand as upregulated genes within LADs radially shift inwards. Our results indicate that the mechanism of action of B-type lamins comes from their role in constraining chromatin motion and spatial positioning of gene-specific loci, heterochromatin, and chromatin domains.

CONCLUSIONS

Our findings suggest that, while B-type lamin degradation does not significantly change genome topology, it has major implications for three-dimensional chromatin conformation at the single-cell level both at the lamina-associated periphery and the non-LAD-associated nuclear interior with concomitant genome-wide transcriptional changes. This raises intriguing questions about the individual and overlapping roles of lamin B1 and lamin B2 in cellular function and disease.

Human cytomegalovirus infection triggers a paracrine senescence loop in renal epithelial cells

Human cytomegalovirus (HCMV) is an opportunistic pathogen causing severe diseases in immunosuppressed individuals. To replicate its double-stranded DNA genome, HCMV induces profound changes in cellular homeostasis that may resemble senescence. However, it remains to be determined whether HCMV-induced senescence contributes to organ-specific pathogenesis. Here, we show a direct cytopathic effect of HCMV on primary renal proximal tubular epithelial cells (RPTECs), a natural setting of HCMV disease. We find that RPTECs are fully permissive for HCMV replication, which endows them with an inflammatory gene signature resembling the senescence-associated secretory phenotype (SASP), as confirmed by the presence of the recently established SenMayo gene set, which is not observed in retina-derived epithelial (ARPE-19) cells. Although HCMV-induced senescence is not cell-type specific, as it can be observed in both RPTECs and human fibroblasts (HFFs), only infected RPTECs show downregulation of LAMINB1 and KI67 mRNAs, and enhanced secretion of IL-6 and IL-8, which are well-established hallmarks of senescence. Finally, HCMV-infected RPTECs have the ability to trigger a senescence/inflammatory loop in an IL-6-dependent manner, leading to the development of a similar senescence/inflammatory phenotype in neighboring uninfected cells. Overall, our findings raise the intriguing possibility that this unique inflammatory loop contributes to HCMV-related pathogenesis in the kidney.

Emerging role of cellular senescence in normal lung development and perinatal lung injury

Cellular senescence is a status of irreversible growth arrest, which can be triggered by the p53/p21cip1 and p16INK4/Rb pathways via intrinsic and external factors. Senescent cells are typically enlarged and flattened, and characterized by numerous molecular features. The latter consists of increased surfaceome, increased residual lysosomal activity at pH 6.0 (manifested by increased activity of senescence-associated beta-galactosidase [SA-β-gal]), senescence-associated mitochondrial dysfunction, cytoplasmic chromatin fragment, nuclear lamin b1 exclusion, telomere-associated foci, and the senescence-associated secretory phenotype. These features vary depending on the stressor leading to senescence and the type of senescence. Cellular senescence plays pivotal roles in organismal aging and in the pathogenesis of aging-related diseases. Interestingly, senescence can also both promote and inhibit wound healing processes. We recently report that senescence as a programmed process contributes to normal lung development. Lung senescence is also observed in Down Syndrome, as well as in premature infants with bronchopulmonary dysplasia and in a hyperoxia-induced rodent model of this disease. Furthermore, this senescence results in neonatal lung injury. In this review, we briefly discuss the molecular features of senescence. We then focus on the emerging role of senescence in normal lung development and in the pathogenesis of bronchopulmonary dysplasia as well as putative signaling pathways driving senescence. Finally, we discuss potential therapeutic approaches targeting senescent cells to prevent perinatal lung diseases.

The cGAS-STING pathway: a therapeutic target in diabetes and its complications

Diabetic wound healing (DWH) represents a major complication of diabetes where inflammation is a key impediment to proper healing. The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway has emerged as a central mediator of inflammatory responses to cell stress and damage. However, the contribution of cGAS-STING activation to impaired healing in DWH remains understudied. In this review, we examine the evidence that cGAS-STING-driven inflammation is a critical factor underlying defective DWH. We summarize studies revealing upregulation of the cGAS-STING pathway in diabetic wounds and discuss how this exacerbates inflammation and senescence and disrupts cellular metabolism to block healing. Partial pharmaceutical inhibition of cGAS-STING has shown promise in damping inflammation and improving DWH in preclinical models. We highlight key knowledge gaps regarding cGAS-STING in DWH, including its relationships with endoplasmic reticulum stress and metal-ion signaling. Elucidating these mechanisms may unveil new therapeutic targets within the cGAS-STING pathway to improve healing outcomes in DWH. This review synthesizes current understanding of how cGAS-STING activation contributes to DWH pathology and proposes future research directions to exploit modulation of this pathway for therapeutic benefit.

Actin contraction controls nuclear blebbing and rupture independent of actin confinement

The nucleus is a mechanically stable compartment of the cell that contains the genome and performs many essential functions. Nuclear mechanical components chromatin and lamins maintain nuclear shape, compartmentalization, and function by resisting antagonistic actin contraction and confinement. Studies have yet to compare chromatin and lamins perturbations side-by-side as well as modulated actin contraction while holding confinement constant. To accomplish this, we used nuclear localization signal green fluorescent protein to measure nuclear shape and rupture in live cells with chromatin and lamin perturbations. We then modulated actin contraction while maintaining actin confinement measured by nuclear height. Wild type, chromatin decompaction, and lamin B1 null present bleb-based nuclear deformations and ruptures dependent on actin contraction and independent of actin confinement. Actin contraction inhibition by Y27632 decreased nuclear blebbing and ruptures while activation by CN03 increased rupture frequency. Lamin A/C null results in overall abnormal shape also reliant on actin contraction, but similar blebs and ruptures as wild type. Increased DNA damage is caused by nuclear blebbing or abnormal shape which can be relieved by inhibition of actin contraction which rescues nuclear shape and decreases DNA damage levels in all perturbations. Thus, actin contraction drives nuclear blebbing, bleb-based ruptures, and abnormal shape independent of changes in actin confinement.