DNA damage-how and why we age?

Exercise alleviates osteoporosis by regulating the secretion of the Senescent Associated Secretory Phenotype

As the elderly population grows, the number of patients with metabolic bone diseases such as osteoporosis has increased sharply, posing a significant threat to public health and social economics. Although pharmacological therapies for osteoporosis demonstrate therapeutic benefits, their prolonged use is associated with varying degrees of adverse effects. As a non-pharmacological intervention, exercise is widely recognized for its cost-effectiveness, safety, and lack of toxic side effects, making it a recommended treatment for osteoporosis prevention and management. Previous studies have demonstrated that exercise can improve metabolic bone diseases by modulating the Senescent Associated Secretory Phenotype (SASP). However, the mechanisms through which exercise influences SASP remain unclear. Therefore, this review aims to summarize the effects of exercise on SASP and elucidate the specific mechanisms by which exercise regulates SASP to alleviate osteoporosis, providing a theoretical basis for osteoporosis through exercise and developing targeted therapies.

Role of stem cells in ageing and age-related diseases

Stem cell functions and ageing are deeply interconnected, continually influencing each other in multiple ways. Stem cells play a vital role in organ maintenance, regeneration, and homeostasis, all of which decline over time due to gradual reduction in their self-renewal, differentiation, and growth factor secretion potential. The functional decline is attributed to damaging extrinsic environmental factors and progressively worsening intrinsic genetic and biochemical processes. These ageing-associated deteriorative changes have been extensively documented, paving the way for the discovery of novel biomarkers of ageing for detection, diagnosis, and treatment of age-related diseases. Age-dependent changes in adult stem cells include numerical decline, loss of heterogeneity, and reduced self-renewal and differentiation, leading to a drastic reduction in regenerative potential and thereby driving the ageing process. Conversely, ageing also adversely alters the stem cell niche, disrupting the molecular pathways underlying stem cell homing, self-renewal, differentiation, and growth factor secretion, all of which are critical for tissue repair and regeneration. A holistic understanding of these molecular mechanisms, through empirical research and clinical trials, is essential for designing targeted therapies to modulate ageing and improve health parameters in older individuals.

GIT2 negatively regulates the NF-κB pathway directly or indirectly by regulating TRAF3 expression to promote osteogenic differentiation of BMSCs

BACKGROUND AIMS

Osteoporosis (OP) is a common disease of aging, which is closely related to the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). DNA damage, as a senescence-associated secretory phenotype (SASP), plays an important role in aging diseases including OP. GIT2 has been identified as a DNA repair gene and alleviates aging-related phenotypes. However, the relationship between GIT2 and osteogenic differentiation of BMSCs remains unclear.

METHODS

Here, we used bioinformatics analysis to identify the gene GIT2, which is closely related to aging, OP and DNA damage, and its downstream targets. Then, H2O2 -induced BMSCs senescence model and ovariectomy-induced mice OP model was established in vitro and in vivo, respectively. Micro-CT, H&E staining, toluidine blue staining, and calcein double labeling were used to analyze bone mass, osteogenic differentiation phenotype, and bone formation rate. Comet assay, Elisa and immunofluorescence were used to analyze senescence-related phenotypes. Western blotting was used to detect the protein levels of GIT2/TRAF3/NF-κB axis and osteogenesis-related markers.

RESULTS

Our results showed that GTI2 and TRAF3 were positively correlated with OP-related markers. On the one hand, GIT2 could inhibit the activation of both canonical and non-canonical NF-κB signaling pathways by positively regulating TRAF3. On the other hand, GIT2 could directly bind to P65, a component of the classical NF-κB signaling pathway, and P52, a component of the non-classical NF-κB signaling pathway, to inhibit their activation, improve DNA damage repair, alleviate cell senescence, and further promote osteogenic differentiation of BMSCs.

CONCLUSIONS

In summary, the present study demonstrates that GIT2 plays a crucial regulatory role in promoting osteogenic differentiation of BMSCs, which provides new ideas for the prevention and treatment of OP and other aging-related diseases.

Roles of Brd4 in Vascular Smooth Muscle Cells: Implications for Aging and Vascular Dysfunction

BACKGROUND

Growing evidence suggests that the epigenetic reader Brd4 (bromodomain-containing protein 4) is involved in aging and aging-related diseases. However, the specific mechanisms by which Brd4 influences vascular aging, especially senescence of vascular smooth muscle cells (SMCs), remain unexplored.

METHODS

Primary cell cultures were established using mouse aortic SMCs and treated with Brd4 inhibitor, ARV-825, or (+)-JQ1. Primary Brd4flox/flox mouse aortic SMCs were transduced with Ad-Cre virus to induce Brd4 knockout (KO). Senescence was assessed through SA-β-gal (senescence-associated β-galactosidase) staining. A mouse model of inducible SMC-specific Brd4 gene KO (SMC-Brd4-KO) was generated with the Cre-LoxP system. The control and SMC-Brd4-KO mice were evaluated for arterial contractility, blood pressure, arterial stiffness, and Ang II (angiotensin II)-induced vascular aging, as well as transcriptome profiling using RNA-sequencing analysis.

RESULTS

Brd4 inhibition with ARV-825, (+)-JQ1, or Brd4 knockdown through Ad-Cre virus in Brd4flox/flox SMCs led to cellular senescence. Induced SMC-Brd4-KO in adult mice prevented neointima formation. SMC-Brd4-KO mice exhibited increased aortic stiffness and blood pressure with enhanced arterial contractility ex vivo. In addition, Brd4 expression was downregulated in aortic tissues of aged mice and senescent human aortic SMCs. Furthermore, SMC-Brd4-KO mice displayed more prominent histopathologic features of vascular aging in response to Ang II infusion. Aortic tissues from SMC-Brd4-KO mice showed a more robust contractile response to Ang II and phenylephrine, accompanied by multiple genetic changes, including alterations in cytoskeleton genes. Transcriptomes of Brd4 KO aortas displayed gene signatures of dampened autophagy, intriguingly associated with a downregulation of microtubule genes, including Tuba4a (α-tubulin). Experiments in vitro with Brd4 KO SMCs demonstrated the potential role of impaired autophagy and depleted α-tubulin in mediating induction of senescence in SMCs.

CONCLUSIONS

Brd4 depletion in SMCs induces senescence, prevents neointima formation, and exacerbates vascular aging, highlighting its crucial roles in vascular functions and diseases.

Suppressed DNA repair capacity in flight attendants after air travel

Elevated cancer risk and compromised reproductive health have been well documented in flight attendants (FA), but the etiology remains unknown. Many studies using cell and animal models suggest that air travel related exposures might plausibly explain the adverse health outcomes observed in flight crew, but our understanding of the underlying biological mechanisms is incomplete. During air travel, FA are constantly exposed to complex mixtures of mutagens in the flight cabin that may contribute to genomic instability by inducing DNA damage and interfering with DNA repair. Defects in DNA repair capacity (DRC) have been associated with risk of cancer and other diseases. To explore our hypothesis that alterations in DNA damage and repair in FA are related to flight travel, we conducted a pilot study of FA's DNA damage and assess global DNA repair efficiency pre and post flight. We collected venous blood samples from nine FA before and after flight. Differential blood cell counts were carried out to assess immune responses and functional assays were performed to assess the DNA damage response. The CometChip assay was employed to quantify baseline DNA damage and repair kinetics for DNA damage induced by X-rays. Fluorescence multiplex based host cell reactivation (FM-HCR) assays were utilized to assess DRC in five major DNA repair pathways. Our findings revealed a significant increase in lymphocyte counts as well as diminished repair of ionizing radiation induced DNA damage and excision of 8oxoG:C lesions in after flight samples. Our results illustrate the potential for using biological samples to identify molecular mechanisms that may implicate impaired genomic stability and altered immune responses in the etiology of excess cancer in FAs.

Cigarette sidestream smoke-induced cellular senescence and the protective role of histone H2AX

Cigarette smoke imposes serious health hazards such as cancer and cardiovascular diseases but is also associated with cellular senescence. Recently, histone loss and modifications are reported as one of the characteristics of cellular senescence. In this study, we examined the relationship between cigarette smoke-induced cellular senescence and histone H2A variant H2AX, an important player in DNA damage response. We exposed normal human skin diploid fibroblast ASF-4-1 to cigarette sidestream smoke (CSS) extract and successfully induced premature senescence. Persistent DNA damages are known to induce cellular senescence. Double strand breaks (DSBs) formation was detected in CSS-treated cells, indicating DSBs could be the cause for the CSS-induced cellular senescence. In the senescent cells, persistent phosphorylation of histone H2AX (γ-H2AX) and unexpected increase of H2AX protein expression was observed. To elucidate the role of H2AX in CSS-induced cellular senescence, we depleted H2AX in ASF-4-1 cells with siRNA. In H2AX-depleted cells, CSS-induced elevated β-galactosidase activity was more prominent. CSS concentration-dependent increase of reactive oxygen species and DSBs formation was also facilitated by H2AX depletion. These results suggest that histone H2AX may have a protective role against DNA damage-induced premature senescence.

Rare biochemical & genetic conditions: clues for broader mechanistic insights

Rare disorders often represent a molecular deviation from hi-fidelity genomic integrity networks and are often perceived as too difficult or unimportant for further mechanistic studies. Here, we synthesize evidence demonstrating how valuable knowledge of biochemical pathways related to rare disorders can be for biomedicine. To this end, we describe several rare congenital lipid, protein, organic acid, and glycan metabolism disorders and discuss how rare phenotypes (such as "extreme responders") and case reports (such as the lenalidomide cases) have provided clues for drug discovery or repurposing. We also discuss how rare disorders such as Gaucher disease and ultra-rare genetic syndromes can provide insights into cancer and mTOR-driven metabolism, respectively. Our discussion highlights the continued value of biochemical pathways and studies in understanding human pathophysiology and drug discovery even in the genomics era.

Protection of the genome and the central exome by peripheral non-coding DNA against DNA damage in health, ageing and age-related diseases

DNA in eukaryotic genomes is under constant assault from both exogenous and endogenous sources, leading to DNA damage, which is considered a major molecular driver of ageing. Fortunately, the genome and the central exome are safeguarded against these attacks by abundant peripheral non-coding DNA. Non-coding DNA codes for small non-coding RNAs that inactivate foreign nucleic acids in the cytoplasm and physically blocks these attacks in the nucleus. Damage to non-coding DNA produced during such blockage is removed in the form of extrachromosomal circular DNA (eccDNA) through nucleic pore complexes. Consequently, non-coding DNA serves as a line of defence for the exome against DNA damage. The total amount of non-coding DNA/heterochromatin declines with age, resulting in a decrease in both physical blockage and eccDNA exclusion, and thus an increase in the accumulation of DNA damage in the nucleus during ageing and in age-related diseases. Here, we summarize recent evidence supporting a protective role of non-coding DNA in healthy and pathological states and argue that DNA damage is the proximate cause of ageing and age-related genetic diseases. Strategies aimed at strengthening the protective role of non-coding DNA/heterochromatin could potentially offer better systematic protection for the dynamic genome and the exome against diverse assaults, reduce the burden of DNA damage to the exome, and thus slow ageing, counteract age-related genetic diseases and promote a healthier life for individuals.

SPRY1 regulates macrophage M1 polarization in skin aging and melanoma prognosis

INTRODUCTION

Skin aging is a complex, multifactorial process involving cellular damage, inflammation, and increased susceptibility to diseases. Despite its importance, the role of SPRY1 in skin aging remains poorly understood. This study aims to investigate the function of SPRY1 in skin aging, particularly its impact on macrophage M1 polarization, and explore its potential as a therapeutic target for mitigating skin aging and melanoma.

METHODS

Bioinformatics analyses were performed using datasets from the GTEx and GEO databases, alongside in vitro cellular experiments. These included Weighted Gene Co-expression Network Analysis (WGCNA), single-cell sequencing, and various cellular assays in RAW264.7 murine monocyte/macrophage leukemia cells and NIH/3T3 mouse skin fibroblasts. The assays comprised gene transfection, Cell Counting Kit-8 (CCK-8) assays, quantitative real-time PCR (qRT-PCR), and measurements of reactive oxygen species (ROS) and superoxide dismutase (SOD) activity.

RESULTS

SPRY1 was identified as a key gene within modules linked to skin aging. Single-cell sequencing revealed its enrichment in macrophages and keratinocytes. Knockdown of SPRY1 in RAW264.7 cells resulted in a shift from M1 to M2 macrophage polarization, reduced oxidative stress, and decreased expression of inflammatory markers. In NIH/3T3 cells, SPRY1 knockdown reduced cell viability and lowered the expression of inflammatory genes. Additionally, SPRY1 expression was downregulated in melanoma, and its reduced levels were associated with poorer survival outcomes.

CONCLUSIONS

SPRY1 accelerates skin aging by promoting macrophage M1 polarization and may serve as a promising therapeutic target. Future research should focus on in vivo validation and further exploration of its regulatory networks to develop novel treatments.

Human-Specific Organization of Proliferation and Stemness in Squamous Epithelia: A Comparative Study to Elucidate Differences in Stem Cell Organization

The mechanisms that influence human longevity are complex and operate on cellular, tissue, and organismal levels. To better understand the tissue-level mechanisms, we compared the organization of cell proliferation, differentiation, and cytoprotective protein expression in the squamous epithelium of the esophagus between mammals with varying lifespans. Humans are the only species with a quiescent basal stem cell layer that is distinctly physically separated from parabasal transit-amplifying cells. In addition to these stark differences in the organization of proliferation, human squamous epithelial stem cells express DNA repair-related markers, such as MECP2 and XPC, which are absent or low in mouse basal cells. Furthermore, we investigated whether the transition from basal to suprabasal is different between species. In humans, the parabasal cells seem to originate from cells detaching from the basement membrane, and these can already begin to proliferate while delaminating. In most other species, delaminating cells have been rare or their proliferation rate is different from that of their human counterparts, indicating an alternative mode of how stem cells maintain the tissue. In humans, the combination of an elevated cytoprotective signature and novel tissue organization may enhance resistance to aging and prevent cancer. Our results point to enhanced cellular cytoprotection and a tissue architecture which separates stemness and proliferation. These are both potential factors contributing to the increased fitness of human squamous epithelia to support longevity by suppressing tumorigenesis. However, the organization of canine oral mucosa shows some similarities to that of human tissue and may provide a useful model to understand the relationship between tissue architecture, gene expression regulation, tumor suppression, and longevity.

Could the inhibition of systemic NLRP3 inflammasome mediate central redox effects of yerba mate? An in silico and pre-clinical translational approach

ETHNOPHARMACOLOGICAL RELEVANCE

Empirically, Ilex paraguariensis A. St. Hil, or yerba-mate, has been used by natives of South America as a stimulant. Nowadays, this plant has gained popularity due to its neuroprotective effects. However, there are few studies on the biochemical-molecular mechanisms of action involved in its effect.

AIM OF THE STUDY

Chemically characterize an aqueous extract of yerba mate (YME) and evaluate if it could suppress the aberrant inflammatory response related to neurodegeneration.

MATERIALS AND METHODS

Macrophages and microglia cells were exposed to lipopolysaccharide (LPS; 100 ng/mL) plus nigericin (100 μM) or quinolinic acid (QA; 5 mM). Cellular viability, oxidative, and inflammatory markers were evaluated. Chemical matrix (HPLC - DAD), antioxidant activity, safety profile in vitro and in vivo, and an in silico docking of main targets were also assessed.

RESULTS

Pre-treatment with YME (15 μg/mL) prevented impairments in redox metabolism and inflammatory markers in BV-2 cells. In macrophages, YME showed similar results to MCC950, an inflammasome inhibitor. YME presented 282.88 mg EAG/g total phenolic content and a redox capacity of 32.94 ± 1.30 μg/mL (IC50), and its major compounds were chlorogenic acid > rutin > ferulic acid > catechin > sinapic acid. Chlorogenic acid and rutin presented a high affinity to the MCC950 region. Additionally, YME did not cause genotoxicity and was safe in vivo.

CONCLUSION

YME has significantly affected macrophages and microglia by regulating the NLRP3 inflammatory pathway.

A reciprocal relationship between markers of genomic DNA damage and alpha-synuclein pathology in dementia with Lewy bodies

BACKGROUND

DNA damage and DNA damage repair (DDR) dysfunction are insults with broad implications for cellular physiology and have been implicated in various neurodegenerative diseases. Alpha-synuclein (aSyn), a pre-synaptic and nuclear protein associated with neurodegenerative disorders known as synucleinopathies, has been associated with DNA double strand break (DSB) repair. However, although nuclear aSyn pathology has been observed in cortical tissue of dementia with Lewy body (DLB) cases, whether such nuclear pathology coincides with the occurrence of DNA damage has not previously been investigated. Moreover, the specific types of DNA damage elevated in DLB cases and the contribution of DNA damage towards Lewy body (LB) formation is unknown.

METHODS

DNA damage and aSyn pathology were assessed in fixed lateral temporal cortex from clinically and neuropathologically confirmed DLB cases and controls, as well as in cortical tissue from young 3-month-old presymptomatic A30P-aSyn mice. Frozen lateral temporal cortex from DLB and control cases was subject to nuclear isolation, western blotting, aSyn seed amplification and proteomic characterisation via mass spectrometry.

RESULTS

We detected seed-competent nuclear aSyn, and elevated nuclear serine-129 phosphorylation in DLB temporal cortex, alongside the accumulation of DSBs in neuronal and non-neuronal cellular populations. DNA damage was also present in cortical tissue from presymptomatic A30P mice, demonstrating it is an early insult closely associated with pathogenic aSyn. Strikingly, in postmortem DLB tissue, markers of genomic DNA damage-derived cytoplasmic DNA (CytoDNA) were evident within the majority of LBs examined. The observed cellular pathology was consistent with nuclear upregulation of associated DDR proteins, particularly those involved in base excision repair and DSB repair pathways.

CONCLUSIONS

Collectively our study demonstrates the accumulation of seed-competent pathological nuclear associated aSyn, alongside nuclear DNA damage and the potential involvement of DNA damage derived cytoDNA species in cytoplasmic aSyn pathology. Ultimately, our study supports the hypothesis of a reciprocal relationship between aSyn pathology and nuclear DNA damage and highlights a potential underlying role for DNA damage in pathological mechanisms relevant to DLB, as well as other synucleinopathies, opening novel possibilities for diagnosis and treatment.

Unravelling Convergent Signaling Mechanisms Underlying the Aging-Disease Nexus Using Computational Language Analysis

Multiple lines of evidence suggest that multiple pathological conditions and diseases that account for the majority of human mortality are driven by the molecular aging process. At the cellular level, aging can largely be conceptualized to comprise the progressive accumulation of molecular damage, leading to resultant cellular dysfunction. As many diseases, e.g., cancer, coronary heart disease, Chronic obstructive pulmonary disease, Type II diabetes mellitus, or chronic kidney disease, potentially share a common molecular etiology, then the identification of such mechanisms may represent an ideal locus to develop targeted prophylactic agents that can mitigate this disease-driving mechanism. Here, using the input of artificial intelligence systems to generate unbiased disease and aging mechanism profiles, we have aimed to identify key signaling mechanisms that may represent new disease-preventing signaling pathways that are ideal for the creation of disease-preventing chemical interventions. Using a combinatorial informatics approach, we have identified a potential critical mechanism involving the recently identified kinase, Dual specificity tyrosine-phosphorylation-regulated kinase 3 (DYRK3) and the epidermal growth factor receptor (EGFR) that may function as a regulator of the pathological transition of health into disease via the control of cellular fate in response to stressful insults.

Endogenous TDP-43 mislocalization in a novel knock-in mouse model reveals DNA repair impairment, inflammation, and neuronal senescence

TDP-43 mislocalization and aggregation are key pathological features of amyotrophic lateral sclerosis (ALS)- and frontotemporal dementia (FTD). However, existing transgenic hTDP-43 WT or ∆NLS-overexpression animal models primarily focus on late-stage TDP-43 proteinopathy. To complement these models and to study the early-stage motor neuron-specific pathology during pre-symptomatic phases of disease progression, we generated a new endogenous knock-in (KI) mouse model using a combination of CRISPR/Cas9 and FLEX Cre-switch strategy for the conditional expression of a mislocalized Tdp-43∆NLS variant of mouse Tdp-43. This variant is expressed either in the whole body (WB) or specifically in the motor neurons (MNs) in two distinct models. These mice exhibit loss of nuclear Tdp-43, with concomitant cytosolic accumulation and aggregation in targeted cells, leading to increased DNA double-strand breaks (DSBs), signs of inflammation, and associated cellular senescence. Notably, unlike WT Tdp-43, which functionally interacts with Xrcc4 and DNA Ligase 4, the key DSB repair proteins in the non-homologous end-joining (NHEJ) pathway, the Tdp-43∆NLS mutant sequesters them into cytosolic aggregates, exacerbating neuronal damage in mouse brain. The mutant mice also exhibit myogenic degeneration in hindlimb soleus muscles and distinct motor deficits, consistent with the characteristics of motor neuron disease (MND). Our findings reveal progressive degenerative mechanisms in motor neurons expressing endogenous Tdp-43∆NLS mutant, independent of Tdp-43 overexpression or other confounding factors. Thus, this unique Tdp-43 KI mouse model, which displays key molecular and phenotypic features of Tdp-43 proteinopathy, offers a significant opportunity to characterize the early-stage progression of MND further and also opens avenues for developing DNA repair-targeted approaches for treating TDP-43 pathology-linked neurodegenerative diseases.

tRNA-Derived Fragments in Age-Related Diseases: A Systematic Review

Aging is a progressive weakening of numerous functions of organisms resulting in diminished abilities to safeguard against environmental damage and augment physiological harmony. It is not a disease in itself; however, it is a main cause of debilitating and life-threatening chronic aging-related diseases (ARDs). tRNA-derived fragments (tDRs) are stable forms of tRNAs of 14-35 nt in length that function as regulatory small-RNA molecules. Here we aimed to perform a systematic review of original articles on the involvement of tDRs in the etiology of ARDs: their identification and characterization. The systematic review was conducted according to the Cochrane Handbook guidelines and the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) statement. Based on the eligibility criteria defined for the study, 21 original articles were included in this systematic review, covering 11 ARDs. The preferred research method used to study tDRs was high-throughput sequencing combined with RT-qPCR, and as a result, a number of tDRs were implicated in ARDs. Importantly, an in-depth analysis of the articles allowed us to identify several shortcomings: (i) the tDRs nomenclature varies between studies and articles, making it often difficult to precisely identify molecules differentiating in a given disease; (ii) the chosen tDRs have all been studied for a miRNA-like mechanism of action; however, tDRs also function in RNAi-independent ways, which need to be studied as well; (iii) to precisely identify tDRs, the sequencing techniques that overcome the issues of modifications harbored by tRNAs must be used.

JP4-039 protects chondrocytes from ferroptosis to attenuate osteoarthritis progression by promoting Pink1/Parkin-dependent mitophagy

Background

Osteoarthritis (OA) is the most common degenerative joint disease, and its main pathological mechanism is articular cartilage degeneration. The purpose of this study was to investigate the role of mitophagy in the pathogenesis of chondrocyte ferroptosis in OA.

Methods

The expressions of ferroptosis related proteins (GPX4, FTH1, COX2) and ubiquitin-dependent mitophagy related proteins (PARKIN, PINK1) in the intact and injured areas of OA cartilage were analyzed. Nitro oxide JP4-039, a mitochondrial targeting antioxidant, has bifunctional role of targeting mitochondria. Then we evaluated the potential protective effect of JP4-039 in OA using the destabilization of medial meniscus (DMM)-induced OA model, as well as tert-butyl hydrogen peroxide (TBHP)-treated primary mouse chondrocytes and human cartilage explants.

Results

The concentrations of iron and lipid peroxidation and the expression of ferroptosis drivers in the damaged areas of human OA cartilages were significantly higher than those in the intact cartilage. Pink1/Parkin-dependent mitophagy decreased in the injured area of human OA cartilage and was negatively correlated with ferroptosis. Then, the toxicity and effectiveness of JP4-039 are tested to determine its working concentration. Next, at the molecular biological level, we found that JP4-039 showed the effect of anti-chondrocyte ferroptosis. Moreover, it was verified on DMM-induced OA model mice, that JP4-039 could delay the progression of OA. Finally, JP4-039 was re-verified in vivo and in vitro to inhibit chondrocyte ferroptosis and delay the progression of OA by promoting Pink1/Parkin-dependent mitophagy.

Conclusion

JP4-039 inhibits ferroptosis of chondrocytes by promoting Pink1/Parkin-dependent mitophagy and delays OA progression.

Nucleotide Excision Repair: Insights into Canonical and Emerging Functions of the Transcription/DNA Repair Factor TFIIH

Nucleotide excision repair (NER) is a universal cut-and-paste DNA repair mechanism that corrects bulky DNA lesions such as those caused by UV radiation, environmental mutagens, and some chemotherapy drugs. In this review, we focus on the human transcription/DNA repair factor TFIIH, a key player of the NER pathway in eukaryotes. This 10-subunit multiprotein complex notably verifies the presence of a lesion and opens the DNA around the damage via its XPB and XPD subunits, two proteins identified in patients suffering from Xeroderma Pigmentosum syndrome. Isolated as a class II gene transcription factor in the late 1980s, TFIIH is a prototypic molecular machine that plays an essential role in both DNA repair and transcription initiation and harbors a DNA helicase, a DNA translocase, and kinase activity. More recently, TFIIH subunits have been identified as participating in other cellular processes, including chromosome segregation during mitosis, maintenance of mitochondrial DNA integrity, and telomere replication.

Ferroptosis in senescence and age-related diseases: pathogenic mechanisms and potential intervention targets

As the global population continues to age, the prevalence of age-related diseases is increasing, significantly influencing social and economic development, the stability of social security systems, and progress in medical technology. Ferroptosis, a recently discovered form of programmed cell death driven by iron-dependent lipid peroxidation, has emerged as a key area of research. Studies have revealed a strong association between ferroptosis and senescence. In this article, we systematically summarize the molecular mechanisms and associated signaling pathways underlying ferroptosis, emphasizing its pivotal role in the onset and progression of age-related diseases. By providing new perspectives, we aim to advance understanding of the pathogenesis of age-related diseases and guide the development of effective intervention strategies.

Reduction of DNA Topoisomerase Top2 Reprograms the Epigenetic Landscape and Extends Health and Life Span Across Species

DNA topoisomerases are essential molecular machines that manage DNA topology in the cell and play important roles in DNA replication and transcription. We found that knocking down the enzyme topoisomerase Top2 or its mammalian homolog TOP2B increases the lifespan of S. cerevisiae, C. elegans, and mice. TOP2B reduction also extends the health span of mice and alleviates the pathologies of aging in multiple tissues. At the cellular/molecular level, TOP2B reduction alleviates the major hallmarks of aging, including senescence, DNA damage, and deregulated nutrient sensing. We observed that TOP2B reduction changes the epigenetic landscape of various tissues in old mice toward that of the young animals, and differentially downregulates genes with active promoter and high expression. Our observations suggest that Top2 reduction confers pro-longevity effect across species possibly through a conserved mechanism and may be a promising strategy for longevity intervention.

The metabolic basis of cancer-related fatigue

Although we are all familiar with the sensation of fatigue, there are still profound divergences on what it represents and its mechanisms. Fatigue can take various forms depending on the condition in which it develops. Cancer-related fatigue is considered a symptom of exhaustion that is often present at the time of diagnosis, increases in intensity during cancer therapy, and does not always recede after completion of treatment. It is usually attributed to the inflammation induced by damage-associated molecular patterns released by tumor cells during cancer progression and in response to its treatment. In this review, we argue that it is necessary to go beyond the symptoms of fatigue to understand its nature and mechanisms. We propose to consider fatigue as a psychobiological process that regulates the behavioral activities an organism engages in to satisfy its needs, according to its physical ability to do so and to the capacity of its intermediary metabolism to exploit the resources procured by these activities. This last aspect is critical as it implies that these metabolic aspects need to be considered to understand fatigue. Based on the findings we have accumulated over several years of studying fatigue in diverse murine models of cancer, we show that energy metabolism plays a key role in the development and persistence of this condition. Cancer-related fatigue is dependent on the energy requirements of the tumor and the negative impact of cancer therapy on the mitochondrial function of the host. When inflammation is present, it adds to the organism's energy expenses. The organism needs to adjust its metabolism to the different forms of cellular stress it experiences thanks to specialized communication factors known as mitokines that act locally and at a distance from the cells in which they are produced. They induce the subjective, behavioral, and metabolic components of fatigue by acting in the brain. Therefore, the targeting of mitokines and their brain receptors offers a window of opportunity to treat fatigue when it is no longer adaptive but an obstacle to the quality of life of cancer survivors.

"Energetics of the outer retina II: Calculation of a spatio-temporal energy budget in retinal pigment epithelium and photoreceptor cells based on quantification of cellular processes"

The outer retina (OR) is highly energy demanding. Impaired energy metabolism combined with high demands are expected to cause energy insufficiencies that make the OR susceptible to complex blinding diseases such as age-related macular degeneration (AMD). Here, anatomical, physiological and quantitative molecular data were used to calculate the ATP expenditure of the main energy-consuming processes in three cell types of the OR for the night and two different periods during the day. The predicted energy demands in a rod dominated (perifovea) area are 1.69 x 1013 ATP/s/mm2 tissue in the night and 6.53 x 1012 ATP/s/mm2 tissue during the day with indoor light conditions. For a cone-dominated foveal area the predicted energy demands are 6.41 x 1012 ATP/s/mm2 tissue in the night and 6.75 x 1012 ATP/s/mm2 tissue with indoor light conditions during daytime. We propose the likely need for diurnal/circadian shifts in energy demands to efficiently stagger all energy consuming processes. Our data provide insights into vulnerabilities in the aging OR and suggest that diurnal constraints may be important when considering therapeutic interventions to optimize metabolism.

Geroscience in heart failure: the search for therapeutic targets in the shared pathobiology of human aging and heart failure

Age is a major risk factor for heart failure, but one that has been historically viewed as non-modifiable. Emerging evidence suggests that the biology of aging is malleable, and can potentially be intervened upon to treat age-associated chronic diseases, such as heart failure. While aging biology represents a new frontier for therapeutic target discovery in heart failure, the challenges of translating Geroscience research to the clinic are multifold. In this review, we propose a strategy that prioritizes initial target discovery in human biology. We review the rationale for starting with human omics, which has generated important insights into the shared (patho)biology of human aging and heart failure. We then discuss how this knowledge can be leveraged to identify the mechanisms of aging biology most relevant to heart failure. Lastly, we provide examples of how this human-first Geroscience approach, when paired with rigorous functional assessments in preclinical models, is leading to early-stage clinical development of gerotherapeutic approaches for heart failure.

Broad repression of DNA repair genes in senescent cells identified by integration of transcriptomic data

Cellular senescence plays a significant role in tissue aging. Senescent cells, which resist apoptosis while remaining metabolically active, generate endogenous DNA-damaging agents, primarily reactive oxygen species. Efficient DNA repair is therefore crucial in these cells, especially when they undergo senescence escape, resuming DNA replication and cellular proliferation. To investigate whether senescent cell transcriptomes reflect adequate DNA repair capacity, we conducted a comprehensive meta-analysis of 60 transcriptomic datasets comparing senescent to proliferating cells. Our analysis revealed a striking downregulation of genes encoding essential components across DNA repair pathways in senescent cells. This includes pathways active in different cell cycle phases such as nucleotide excision repair, base excision repair, nonhomologous end joining and homologous recombination repair of double-strand breaks, mismatch repair and interstrand crosslink repair. The downregulation observed suggests a significant accumulation of DNA lesions. Experimental monitoring of DNA repair readouts in cells that underwent radiation-induced senescence supported this conclusion. This phenomenon was consistent across various senescence triggers and was also observed in primary cell lines from aging individuals. These findings highlight the potential of senescent cells as 'ticking bombs' in aging-related diseases and tumors recurring following therapy-induced senescence.

Single-cell and bulk transcriptional profiling of mouse ovaries reveals novel genes and pathways associated with DNA damage response in oocytes

Immature oocytes enclosed in primordial follicles stored in female ovaries are under constant threat of DNA damage induced by endogenous and exogenous factors. Checkpoint kinase 2 (CHEK2) is a key mediator of the DNA damage response (DDR) in all cells. Genetic studies have shown that CHEK2 and its downstream targets, p53, and TAp63, regulate primordial follicle elimination in response to DNA damage. However, the mechanism leading to their demise is still poorly characterized. Single-cell and bulk RNA sequencing were used to determine the DDR in wild-type and Chek2-deficient ovaries. A low but oocyte-lethal dose of ionizing radiation induces ovarian DDR that is solely dependent on CHEK2. DNA damage activates multiple response pathways related to apoptosis, p53, interferon signaling, inflammation, cell adhesion, and intercellular communication. These pathways are differentially employed by different ovarian cell types, with oocytes disproportionately affected by radiation. Novel genes and pathways are induced by radiation specifically in oocytes, shedding light on their sensitivity to DNA damage, and implicating a coordinated response between oocytes and pregranulosa cells within the follicle. These findings provide a foundation for future studies on the specific mechanisms regulating oocyte survival in the context of aging, therapeutic and environmental genotoxic exposures.

Characterization of radiations-induced genomic structural variations in Arabidopsis thaliana

DNA, is assaulted by endogenous and exogenous agents that lead to the formation of damage. In order to maintain genome integrity DNA repair pathways must be efficiently activated to prevent mutations and deleterious chromosomal rearrangements. Conversely, genome rearrangement is also necessary to allow genetic diversity and evolution. The antagonist interaction between maintenance of genome integrity and rearrangements determines genome shape and organization. Therefore, it is of great interest to understand how the whole linear genome structure behaves upon formation and repair of DNA damage. For this, we used long reads sequencing technology to identify and to characterize genomic structural variations (SV) of wild-type Arabidopsis thaliana somatic cells exposed either to UV-B, to UV-C or to protons irradiations. We found that genomic regions located in heterochromatin are more prone to form SVs than those located in euchromatin, highlighting that genome stability differs along the chromosome. This holds true in Arabidopsis plants deficient for the expression of master regulators of the DNA damage response (DDR), ATM (Ataxia-telangiectasia-mutated) and ATR (Ataxia-telangiectasia-mutated and Rad3-related), suggesting that independent and alternative surveillance processes exist to maintain integrity in genic regions. Finally, the analysis of the radiations-induced deleted regions allowed determining that exposure to UV-B, UV-C and protons induced the microhomology-mediated end joining mechanism (MMEJ) and that both ATM and ATR repress this repair pathway.

Hydra has mammal-like mutation rates facilitating fast adaptation despite its nonaging phenotype

Growing evidence suggests that somatic mutations may be a major cause of the aging process. However, it remains to be tested whether the predictions of the theory also apply to species with longer life spans than humans. Hydra is a genus of freshwater polyps with remarkable regeneration abilities and a potentially unlimited life span under laboratory conditions. By genome sequencing of single cells and whole animals, we found that the mutation rates in Hydra's stem cells are even slightly higher than in humans or mice. A potential explanation for this deviation from the prediction of the theory may lie in the adaptability offered by a higher mutation rate, as we were able to show that the genome of the widely studied Hydra magnipapillata strain 105 has undergone a process of strong positive selection since the strain's cultivation 50 years ago. This most likely represents a rapid adaptation to the drastically altered environmental conditions associated with the transition from the wild to laboratory conditions. Processes under positive selection in captive animals include pathways associated with Hydra's simple nervous system, its nucleic acid metabolic process, cell migration, and hydrolase activity.

Quinazoline derivatives inhibit cell growth of prostate cancer as a WRN helicase dependent manner by regulating DNA damage repair and microsatellite instability

WRN helicase is a crucial target of synthetic death in cancer and has a unique advantage in the treatment of microsatellite unstable cancers. Our previous studies have found that quinazoline derivatives showed the WRN-dependent antiproliferative activity. In this study, a series of new quinazoline derivatives were designed and synthesized by optimizing the structure, and evaluating the targeting and sensitivity to WRN helicase. Cell growth inhibition experiments on WRN overexpressing PC3 cells (PC3-WRN) showed that the antiproliferative activity of some compounds was significantly dependent on WRN helicase. Moreover, the antitumor activity of 9in vivo was significantly decreased in the nude mouse model constructed with WRN knockdown PC3 cells (PC3-shWRN) compare (P < 0.01) to the control group. The molecular docking and CETSA results showed that 9 directly binds to WRN protein. Mechanism studies have confirmed that 9 targeted WRN, and may affect the binding between WRN and other key regulators, to destroy the repair function and regulate genomic stability. In addition, 9 also has suitable pharmacokinetic parameters and low toxicity in vivo. This result indicates that the quinazoline derivative 9 could be a novel WRN function inhibitor for the treatment of prostate cancer.

Repetitive element transcript accumulation is associated with inflammaging in humans

Chronic, low-grade inflammation increases with aging, contributing to functional declines and diseases that reduce healthspan. Growing evidence suggests that transcripts from repetitive elements (RE) in the genome contribute to this "inflammaging" by stimulating innate immune activation, but evidence of RE-associated inflammation with aging in humans is limited. Here, we present transcriptomic and clinical data showing that RE transcript levels are positively related to gene expression of innate immune sensors, and to serum interleukin 6 (a marker of systemic inflammation), in a large group of middle-aged and older adults. We also: (1) use transcriptomics and whole-genome bisulfite (methylation) sequencing to show that many RE may be hypomethylated with aging, and that aerobic exercise, a healthspan-extending intervention, reduces RE transcript levels and increases RE methylation in older adults; and (2) extend our findings in a secondary dataset demonstrating age-related changes in RE chromatin accessibility. Collectively, our data support the idea that age-related RE transcript accumulation may play a role in inflammaging in humans, and that RE dysregulation with aging may be due in part to upstream epigenetic changes.

Synergy trap for guardian angels of DNA: Unraveling the anticancer potential of phthalazinone-thiosemicarbazone hybrids through dual PARP-1 and TOPO-I inhibition

Targeting DNA repair, like PARP-1 and TOPO-I, shows promise in cancer therapy. However, resistance to single agents requires complex and costly combination strategies with significant side effects. Thus, there's an urgent need for single agents with dual inhibition. Current dual inhibitors focusing on the C-4 position of the phthalazinone core for PARP inhibition often have high molecular weights. Clinical use of PARP inhibitors is limited by hematological and other toxicities from concurrent PARP-2 inhibition. They're mainly effective in gynecological cancers, despite high PARP-1 and TOPO-I expression in various cancers. Moreover, their efficacy is limited to BRCA1-expressing breast cancer. In this study, we synthesized 27 dual inhibitors for PARP-1 and TOPO-I with molecular weights below 500 g/mol through hybridizing a phthalazinone core with a thiosemicarbazone linker. Among these, 6c demonstrated exceptional broad spectrum and potency against the NCI 60 cancer cell lines, with GI50 values from 1.65 to 5.63 µM. Notably, 6c exposed the highest PARP-1 inhibition (IC50 = 32.2 ± 3.26 nM) and a selectivity over PARP-2 (IC50 = 2844 ± 111 nM). Furthermore, 6c's inhibition of TOPO-I (IC50 = 46.2 ± 3.3 nM) surpassed the control camptothecin by eleven-fold. Mechanistically, 6c disrupted the cell cycle at the S phase, induced apoptosis, and displayed a favorable safety profile against normal cells. Compound 6c induced PARP trapping and synthetic lethality and showed high efficacy on BRCA1-expressing cell lines. So, decreasing the likelihood of cancer cell resistance to chemotherapy. Drug-likeness predictions and molecular modeling were also performed.

Alzheimer's Disease: Exploring the Landscape of Cognitive Decline

Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterized by cognitive decline, memory loss, and impaired daily functioning. The pathology of AD is marked by the accumulation of amyloid beta plaques and tau protein tangles in the brain, along with neuroinflammation and synaptic dysfunction. Genetic factors, such as mutations in APP, PSEN1, and PSEN2 genes, as well as the APOE ε4 allele, contribute to increased risk of acquiring AD. Currently available treatments provide symptomatic relief but do not halt disease progression. Research efforts are focused on developing disease-modifying therapies that target the underlying pathological mechanisms of AD. Advances in identification and validation of reliable biomarkers for AD hold great promise for enhancing early diagnosis, monitoring disease progression, and assessing treatment response in clinical practice in effort to alleviate the burden of this devastating disease. In this paper, we analyze data from the CAS Content Collection to summarize the research progress in Alzheimer's disease. We examine the publication landscape in effort to provide insights into current knowledge advances and developments. We also review the most discussed and emerging concepts and assess the strategies to combat the disease. We explore the genetic risk factors, pharmacological targets, and comorbid diseases. Finally, we inspect clinical applications of products against AD with their development pipelines and efforts for drug repurposing. The objective of this review is to provide a broad overview of the evolving landscape of current knowledge regarding AD, to outline challenges, and to evaluate growth opportunities to further efforts in combating the disease.

The diverse functions of DYRK2 in response to cellular stress

To maintain microenvironmental and cellular homeostasis, cells respond to multiple stresses by activating characteristic cellular mechanisms consisting of receptors, signal transducers, and effectors. Dysfunction of these mechanisms can trigger multiple human diseases as well as cancers. Dual-specificity tyrosine-regulated kinases (DYRKs) are members of the CMGC group and are evolutionarily conserved from yeast to mammals. Previous studies revealed that DYRK2 has important roles in the regulation of the cell cycle and survival in cancer cells. On the other hand, recent studies show that DYRK2 also exhibits significant functions in multiple cellular stress responses and in maintaining cellular homeostasis. Hence, the further elucidation of mechanisms underlying DYRK2's diverse responses to various stresses helps to promote the advancement of innovative clinical therapies and pharmacological drugs. This review summarizes the molecular mechanisms of DYRK2, particularly focusing on cellular stress responses.

Exploring the Potential of Anthocyanins for Repairing Photoaged Skin: A Comprehensive Review

Long-term exposure to ultraviolet (UV) rays can result in skin photoaging, which is primarily characterized by dryness, roughness, pigmentation, and a loss of elasticity. However, the clinical drugs commonly employed to treat photoaged skin often induce adverse effects on the skin. Anthocyanins (ACNs) are water-soluble pigments occurring abundantly in various flowers, fruits, vegetables, and grains and exhibiting a range of biological activities. Studies have demonstrated that ACNs contribute to the repair of photoaged skin due to their diverse biological characteristics and minimal side effects. Evidence suggests that the stability of ACNs can be enhanced through encapsulation or combination with other substances to improve their bioavailability and permeability, ultimately augmenting their efficacy in repairing photoaged skin. A growing body of research utilizing cell lines, animal models, and clinical studies has produced compelling data demonstrating that ACNs mitigate skin photoaging by reducing oxidative stress, alleviating the inflammatory response, improving collagen synthesis, alleviating DNA damage, and inhibiting pigmentation. This review introduces sources of ACNs while systematically summarizing their application forms as well as mechanisms for repairing photoaged skin. Additionally, it explores the potential role of ACNs in developing functional foods. These findings may provide valuable insight into using ACNs as promising candidates for developing functional products aimed at repairing photoaged skin.

Safeguarding genomic integrity in beta-cells: implications for beta-cell differentiation, growth, and dysfunction

The maintenance of optimal glucose levels in the body requires a healthy reserve of the insulin producing pancreatic beta-cells. Depletion of this reserve due to beta-cell dysfunction and death results in development of diabetes. Recent findings highlight unresolved DNA damage as a key contributor to beta-cell defects in diabetes. Beta-cells face various stressors and metabolic challenges throughout life, rendering them susceptible to DNA breaks. The post-mitotic, long-lived phenotype of mature beta-cells further warrants robust maintenance of genomic integrity. Failure to resolve DNA damage during beta-cell development, therefore, can result in an unhealthy reserve of beta-cells and predispose to diabetes. Yet, the molecular mechanisms safeguarding beta-cell genomic integrity remain poorly understood. Here, we focus on the significance of DNA damage in beta-cell homeostasis and postulate how cellular expansion, epigenetic programming, and metabolic shifts during development may impact beta-cell genomic integrity and health. We discuss recent findings demonstrating a physiological role for DNA breaks in modulating transcriptional control in neurons, which share many developmental programs with beta-cells. Finally, we highlight key gaps in our understanding of beta-cell genomic integrity and discuss emerging areas of interest.

New Insights into the Fanconi Anemia Pathogenesis: A Crosstalk Between Inflammation and Oxidative Stress

Fanconi anemia (FA) represents a rare hereditary disease; it develops due to germline pathogenic variants in any of the 22 currently discovered FANC genes, which interact with the Fanconi anemia/breast cancer-associated (FANC/BRCA) pathway to maintain genome integrity. FA is characterized by a triad of clinical traits, including congenital anomalies, bone marrow failure (BMF) and multiple cancer susceptibility. Due to the complex genetic background and a broad spectrum of FA clinical symptoms, the diagnostic process is complex and requires the use of classical cytogenetic, molecular cytogenetics and strictly molecular methods. Recent findings indicate the interplay of inflammation, oxidative stress, disrupted mitochondrial metabolism, and impaired intracellular signaling in the FA pathogenesis. Additionally, a shift in the balance towards overproduction of proinflammatory cytokines and prooxidant components in FA is associated with advanced myelosuppression and ultimately BMF. Although the mechanism of BMF is very complex and needs further clarification, it appears that mutual interaction between proinflammatory cytokines and redox imbalance causes pancytopenia. In this review, we summarize the available literature regarding the clinical phenotype, genetic background, and diagnostic procedures of FA. We also highlight the current understanding of disrupted autophagy process, proinflammatory state, impaired signaling pathways and oxidative genotoxic stress in FA pathogenesis.

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.

Plasma Proteomics of Type 2 Diabetes, Hypertension, and Co-Existing Diabetes/Hypertension in Thai Adults

The study explored proteomics to better understand the relationship between type 2 diabetes (T2DM) and hypertension (HT) in Thai adults, using shotgun proteomics and bioinformatics analysis. Plasma samples were taken from 61 subjects: 14 healthy subjects (mean age = 40.85 ± 7.12), 13 with T2DM (mean age = 57.38 ± 6.03), 16 with HT (mean age = 66.87 ± 10.09), and 18 with coexisting T2DM/HT (mean age = 58.22 ± 10.65). Proteins were identified using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Protein-protein interactions were analyzed using the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) version 11.5. We identified six unique proteins in T2DM patients, including translationally controlled 1 (TPT1) and nibrin (NBN), which are associated with the DNA damage response. In HT patients, seven unique proteins were identified, among them long-chain fatty acid-CoA ligase (ASCL), which functions in the stimulation of triacylglycerol and cholesterol synthesis, and NADPH oxidase activator 1 (NOXA1), which is involved in high blood pressure via angiotensin II-induced reactive oxygen species (ROS)-generating systems. In coexisting T2DM/HT patients, six unique proteins were identified, of which two-microtubule-associated protein 1A (MAP1A)-might be involved in dementia via RhoB-p53 and diacylglycerol kinase beta (DGKB), associated with lipid metabolism. This study identified new candidate proteins that are possibly involved in the pathology of these diseases.

The SASP factor IL-6 sustains cell-autonomous senescent cells via a cGAS-STING-NFκB intracrine senescent noncanonical pathway

Senescent cells produce a Senescence-Associated Secretory Phenotype (SASP) that involves factors with diverse and sometimes contradictory activities. One key SASP factor, interleukin-6 (IL-6), has the potential to amplify cellular senescence in the SASP-producing cells in an autocrine action, while simultaneously inducing proliferation in the neighboring cells. The underlying mechanisms for the contrasting actions remain unclear. We found that the senescence action does not involve IL-6 secretion nor the interaction with the receptor expressed in the membrane but is amplified through an intracrine mechanism. IL-6 sustains intracrine senescence interacting with the intracellular IL-6 receptor located in anterograde traffic specialized structures, with cytosolic DNA, cGAS-STING, and NFκB activation. This pathway triggered by intracellular IL-6 significantly contributes to cell-autonomous induction of senescence and impacts in tumor growth control. Inactivation of IL-6 in somatotrophic senescent cells transforms them into strongly tumorigenic in NOD/SCID mice, while re-expression of IL-6 restores senescence control of tumor growth. The intracrine senescent IL-6 pathway is further evidenced in three human cellular models of therapy-induced senescence. The compartmentalization of the intracellular signaling, in contrast to the paracrine tumorigenic action, provides a pathway for IL-6 to sustain cell-autonomous senescent cells, driving the SASP, and opens new avenues for clinical consideration to senescence-based therapies.

Pituitary tumor‑transforming gene 1 regulates the senescence and apoptosis of oral squamous cell carcinoma in a p21‑dependent DNA damage response manner

Pituitary tumor‑transforming gene 1 (PTTG1), also known as securin, is a proto‑oncogene involved in the development of various cancers by promoting cell proliferation and mobility. However, its underlying biological mechanisms in oral squamous cell carcinoma (OSCC) progression remain unclear. in the present study, it was sought to elucidate the role of PTTG1 as an oncogene in OSCC progression and was attempted to unravel the underlying mechanism and impact of PTTG1 expression on cell cycle, cell death, and cellular senescence. The effect of double strand break on PTTG1 expression was investigated in OSCC growth. To identify the role of PTTG1 in OSCC growth, the cell viability and senescence was analyzed by EdU and senescence‑associated beta‑galactosidase (SA‑β‑gal) assay, respectively. To verify the DNA damage‑induced senescence of PTTG1, the chromosomal damage in OSCC was analyzed in vitro. Finally, the effect of PTTG1 on tumor growth and gene expression related to cell viability and DNA damaged‑induced senescence was investigated in vivo. PTTG1 expression was compared between OSCC and healthy patient samples (n=32) using reverse transcription‑quantitative PCR and immunohistochemistry; and it was found that PTTG1 expression was upregulated in OSCC. Small interfering RNA‑mediated knockdown of PTTG1 in two OSCC cell lines revealed that PTTG1 downregulation significantly inhibited cell proliferation and arrested the cell cycle pathway as evidenced by changes in checkpoint genes (such as cyclin D1, E and B1). PTTG1 knockdown also increased apoptosis, as evidenced by the upregulation of apoptotic genes [such as cleaved (c‑) Caspase‑7 and c‑poly (ADP‑ribose) polymerase]. Moreover, PTTG1 downregulation promoted cellular senescence, as shown by western blotting and SA‑β‑gal staining. Finally, senescence‑induced DNA damage was observed in OSCC cells, which accelerates genomic instability, through chromosomal damage analysis. Taken together, the present findings suggested that PTTG1 acts as a proto‑oncogene; regulates cell proliferation, cell cycle, cellular senescence and DNA damage in OSCC; and may serve as a novel diagnostic biomarker and potential therapeutic target for OSCC.

The brain-body energy conservation model of aging

Aging involves seemingly paradoxical changes in energy metabolism. Molecular damage accumulation increases cellular energy expenditure, yet whole-body energy expenditure remains stable or decreases with age. We resolve this apparent contradiction by positioning the brain as the mediator and broker in the organismal energy economy. As somatic tissues accumulate damage over time, costly intracellular stress responses are activated, causing aging or senescent cells to secrete cytokines that convey increased cellular energy demand (hypermetabolism) to the brain. To conserve energy in the face of a shrinking energy budget, the brain deploys energy conservation responses, which suppress low-priority processes, producing fatigue, physical inactivity, blunted sensory capacities, immune alterations and endocrine 'deficits'. We term this cascade the brain-body energy conservation (BEC) model of aging. The BEC outlines (1) the energetic cost of cellular aging, (2) how brain perception of senescence-associated hypermetabolism may drive the phenotypic manifestations of aging and (3) energetic principles underlying the modifiability of aging trajectories by stressors and geroscience interventions.

Biology of Healthy Aging: Biological Hallmarks of Stress Resistance Related and Unrelated to Longevity in Humans

Stress resistance is highly associated with longer and healthier lifespans in various model organisms, including nematodes, fruit flies, and mice. However, we lack a complete understanding of stress resistance in humans; therefore, we investigated how stress resistance and longevity are interlinked in humans. Using more than 180 databases, we identified 541 human genes associated with stress resistance. The curated gene set is highly enriched with genes involved in the cellular response to stress. The Reactome analysis identified 398 biological pathways, narrowed down to 172 pathways using a medium threshold (p-value < 1 × 10-4). We further summarized these pathways into 14 pathway categories, e.g., cellular response to stimuli/stress, DNA repair, gene expression, and immune system. There were overlapping categories between stress resistance and longevity, including gene expression, signal transduction, immune system, and cellular responses to stimuli/stress. The categories include the PIP3-AKT-FOXO and mTOR pathways, known to specify lifespans in the model systems. They also include the accelerated aging syndrome genes (WRN and HGPS/LMNA), while the genes were also involved in non-overlapped categories. Notably, nuclear pore proteins are enriched among the stress-resistance pathways and overlap with diverse metabolic pathways. This study fills the knowledge gap in humans, suggesting that stress resistance is closely linked to longevity pathways but not entirely identical. While most longevity categories intersect with stress-resistance categories, some do not, particularly those related to cell proliferation and beta-cell development. We also note inconsistencies in pathway terminologies with aging hallmarks reported previously, and propose them to be more unified and integral.

The dual role of cellular senescence in human tumor progression and therapy

Cellular senescence, one of the hallmarks of cancer, is characterized by cell cycle arrest and the loss of most normal cellular functions while acquiring a hypersecretory, proinflammatory phenotype. The function of senescent cells in cancer cells varies depending on the cellular conditions. Before the occurrence of cancer, senescent cells act as a barrier to prevent its development. But once cancer has occurred, senescent cells play a procancer role. However, few of the current studies have adequately explained the diversity of cellular senescence across cancers. Herein, we concluded the latest intrinsic mechanisms of cellular senescence in detail and emphasized the senescence-associated secretory phenotype as a key contributor to heterogeneity of senescent cells in tumor. We also discussed five kinds of inducers of cellular senescence and the advancement of senolytics in cancer, which are drugs that tend to clear senescent cells. Finally, we summarized the various effects of senescent cells in different cancers and manifested that their functions may be diametrically opposed under different circumstances. In short, this paper contributes to the understanding of the diversity of cellular senescence in cancers and provides novel insight for tumor therapy.

Food contaminants: Impact of food processing, challenges and mitigation strategies for food security

Food preparation involves the blending of various food ingredients to make more convenient processed food products. It is a long chain process, where each stage posing a risk of accumulating hazardous contaminants in these food systems. Protecting the public health from contaminated foods has become a demanding task in ensuring food safety. This review focused on the causes, types, and health risks of contaminants or hazardous chemicals during food processing. The impact of cooking such as frying, grilling, roasting, and baking, which may lead to the formation of hazardous by-products, including polycyclic aromatic hydrocarbons (PAHs), heterocyclic amines (HCAs), acrylamide, advanced glycation end products (AGEs), furan, acrolein, nitrosamines, 5-hydroxymethylfurfural (HMF) and trans-fatty acids (TFAs). Potential health risks such as carcinogenicity, genotoxicity, neurotoxicity, and cardiovascular effects are emerging as a major problem in the modern lifestyle era due to the increased uptakes of contaminants. Effects of curing, smoking, and fermentation of the meat products led to affect the sensory and nutritional characteristics of meat products. Selecting appropriate cooking methods include temperature, time and the consumption of the food are major key factors that should be considered to avoid the excess level intake of hazardous contaminants. Overall, this study underscores the importance of understanding the risks associated with food preparation methods, strategies for minimizing the formation of harmful compounds during food processing and highlights the need for healthy dietary choices to mitigate potential health hazards.

From Crypts to Cancer: A Holistic Perspective on Colorectal Carcinogenesis and Therapeutic Strategies

Colorectal cancer (CRC) represents a significant global health burden, with high incidence and mortality rates worldwide. Recent progress in research highlights the distinct clinical and molecular characteristics of colon versus rectal cancers, underscoring tumor location's importance in treatment approaches. This article provides a comprehensive review of our current understanding of CRC epidemiology, risk factors, molecular pathogenesis, and management strategies. We also present the intricate cellular architecture of colonic crypts and their roles in intestinal homeostasis. Colorectal carcinogenesis multistep processes are also described, covering the conventional adenoma-carcinoma sequence, alternative serrated pathways, and the influential Vogelstein model, which proposes sequential APC, KRAS, and TP53 alterations as drivers. The consensus molecular CRC subtypes (CMS1-CMS4) are examined, shedding light on disease heterogeneity and personalized therapy implications.

To target cellular senescence in diabetic kidney disease: the known and the unknown

Cellular senescence represents a condition of irreversible cell cycle arrest, characterized by heightened senescence-associated beta-galactosidase (SA-β-Gal) activity, senescence-associated secretory phenotype (SASP), and activation of the DNA damage response (DDR). Diabetic kidney disease (DKD) is a significant contributor to end-stage renal disease (ESRD) globally, with ongoing unmet needs in terms of current treatments. The role of senescence in the pathogenesis of DKD has attracted substantial attention with evidence of premature senescence in this condition. The process of cellular senescence in DKD appears to be associated with mitochondrial redox pathways, autophagy, and endoplasmic reticulum (ER) stress. Increasing accumulation of senescent cells in the diabetic kidney not only leads to an impaired capacity for repair of renal injury, but also the secretion of pro-inflammatory and profibrotic cytokines and growth factors causing inflammation and fibrosis. Current treatments for diabetes exhibit varying degrees of renoprotection, potentially via mitigation of senescence in the diabetic kidney. Targeting senescent cell clearance through pharmaceutical interventions could emerge as a promising strategy for preventing and treating DKD. In this paper, we review the current understanding of senescence in DKD and summarize the possible therapeutic interventions relevant to senescence in this field.

Quantitative analysis of dose dependent DNA fragmentation in dry pBR322 plasmid using long read sequencing and Monte Carlo simulations

Exposure to ionizing radiation can induce genetic aberrations via unrepaired DNA strand breaks. To investigate quantitatively the dose-effect relationship at the molecular level, we irradiated dry pBR322 plasmid DNA with 3 MeV protons and assessed fragmentation yields at different radiation doses using long-read sequencing from Oxford Nanopore Technologies. This technology applied to a reference DNA model revealed dose-dependent fragmentation, as evidenced by read length distributions, showing no discernible radiation sensitivity in specific genetic sequences. In addition, we propose a method for directly measuring the single-strand break (SSB) yield. Furthermore, through a comparative study with a collection of previous works on dry DNA irradiation, we show that the irradiation protocol leads to biases in the definition of ionizing sources. We support this scenario by discussing the size distributions of nanopore sequencing reads in the light of Geant4 and Geant4-DNA simulation toolkit predictions. We show that integrating long-read sequencing technologies with advanced Monte Carlo simulations paves a promising path toward advancing our comprehension and prediction of radiation-induced DNA fragmentation.

HDAC4 influences the DNA damage response and counteracts senescence by assembling with HDAC1/HDAC2 to control H2BK120 acetylation and homology-directed repair

Access to DNA is the first level of control in regulating gene transcription, a control that is also critical for maintaining DNA integrity. Cellular senescence is characterized by profound transcriptional rearrangements and accumulation of DNA lesions. Here, we discovered an epigenetic complex between HDAC4 and HDAC1/HDAC2 that is involved in the erase of H2BK120 acetylation. The HDAC4/HDAC1/HDAC2 complex modulates the efficiency of DNA repair by homologous recombination, through dynamic deacetylation of H2BK120. Deficiency of HDAC4 leads to accumulation of H2BK120ac, impaired recruitment of BRCA1 and CtIP to the site of lesions, accumulation of damaged DNA and senescence. In senescent cells this complex is disassembled because of increased proteasomal degradation of HDAC4. Forced expression of HDAC4 during RAS-induced senescence reduces the genomic spread of γH2AX. It also affects H2BK120ac levels, which are increased in DNA-damaged regions that accumulate during RAS-induced senescence. In summary, degradation of HDAC4 during senescence causes the accumulation of damaged DNA and contributes to the activation of the transcriptional program controlled by super-enhancers that maintains senescence.

Advances in the mechanism of small nucleolar RNA and its role in DNA damage response

Small nucleolar RNAs (snoRNAs) were previously regarded as a class of functionally conserved housekeeping genes, primarily involved in the regulation of ribosome biogenesis by ribosomal RNA (rRNA) modification. However, some of them are involved in several biological processes via complex molecular mechanisms. DNA damage response (DDR) is a conserved mechanism for maintaining genomic stability to prevent the occurrence of various human diseases. It has recently been revealed that snoRNAs are involved in DDR at multiple levels, indicating their relevant theoretical and clinical significance in this field. The present review systematically addresses four main points, including the biosynthesis and classification of snoRNAs, the mechanisms through which snoRNAs regulate target molecules, snoRNAs in the process of DDR, and the significance of snoRNA in disease diagnosis and treatment. It focuses on the potential functions of snoRNAs in DDR to help in the discovery of the roles of snoRNAs in maintaining genome stability and pathological processes.

Ameliorative effects of mesenchymal stromal cells on senescence associated phenotypes in naturally aged rats

BACKGROUND

Aging is a multifaceted process that affects all organ systems. With the increasing trend of population aging, aging-related diseases have resulted in significant medical challenges and socioeconomic burdens. Mesenchymal stromal cells (MSCs), due to their antioxidative stress, immunoregulatory, and tissue repair capabilities, hold promise as a potential anti-aging intervention.

METHODS

In this study, we transplanted MSCs into naturally aged rats at 24 months, and subsequently examined levels of aging-related factors such as β-galactosidase, superoxide dismutase, p16, p21 and malondialdehyde in multiple organs. Additionally, we assessed various aging-related phenotypes in these aged rats, including immune senescence, lipid deposition, myocardial fibrosis, and tissue damage. We also conducted a 16 S ribosomal ribonucleic acid (rRNA) analysis to study the composition of gut microbiota.

RESULTS

The results indicated that MSCs significantly reduced the levels of aging-associated and oxidative stress-related factors in multiple organs such as the heart, liver, and lungs of naturally aging rats. Furthermore, they mitigated chronic tissue damage and inflammation caused by aging, reduced levels of liver lipid deposition and myocardial fibrosis, alleviated aging-associated immunodeficiency and immune cell apoptosis, and positively influenced the gut microbiota composition towards a more youthful state. This research underscores the diverse anti-aging effects of MSCs, including oxidative stress reduction, tissue repair, metabolic regulation, and improvement of immune functions, shedding light on the underlying anti-aging mechanisms associated with MSCs.

CONCLUSIONS

The study confirms that MSCs hold great promise as a potential anti-aging approach, offering the possibility of extending lifespan and improving the quality of life in the elderly population.

An altered cell-specific subcellular distribution of translesion synthesis DNA polymerase kappa (POLK) in aging neurons

Genomic stability is critical for cellular function, however, in the central nervous system highly metabolically active differentiated neurons are challenged to maintain their genome over the organismal lifespan without replication. DNA damage in neurons increases with chronological age and accelerates in neurodegenerative disorders, resulting in cellular and systemic dysregulation. Distinct DNA damage response strategies have evolved with a host of polymerases. The Y-family translesion synthesis (TLS) polymerases are well known for bypassing and repairing damaged DNA in dividing cells. However, their expression, dynamics, and role if any, in enduring postmitotic differentiated neurons of the brain are completely unknown. We show through systematic longitudinal studies for the first time that DNA polymerase kappa (POLK), a member of the Y-family polymerases, is highly expressed in neurons. With chronological age, there is a progressive and significant reduction of nuclear POLK with a concomitant accumulation in the cytoplasm that is predictive of brain tissue age. The reduction of nuclear POLK in old brains is congruent with an increase in DNA damage markers. The nuclear POLK colocalizes with damaged sites and DNA repair proteins. The cytoplasmic POLK accumulates with stress granules and endo/lysosomal markers. Nuclear POLK expression is significantly higher in GABAergic interneurons compared to excitatory pyramidal neurons and lowest in non-neurons, possibly reflective of the inherent biological differences such as firing rates and neuronal activity. Interneurons associated with microglia have significantly higher levels of cytoplasmic POLK in old age. Finally, we show that neuronal activity itself can lead to an increase in nuclear POLK levels and a reduction of the cytoplasmic fraction. Our findings open a new avenue in understanding how different classes of postmitotic neurons deploy TLS polymerase(s) to maintain their genomic integrity over time, which will help design strategies for longevity, healthspan, and prevention of neurodegeneration.

Crosstalk between the DNA damage response and cellular senescence drives aging and age-related diseases

Cellular senescence is a crucial process of irreversible cell-cycle arrest, in which cells remain alive, but permanently unable to proliferate in response to distinct types of stressors. Accumulating evidence suggests that DNA damage builds over time and triggers DNA damage response signaling, leading to cellular senescence. Cellular senescence serves as a platform for the perpetuation of inflammatory responses and is central to numerous age-related diseases. Defects in DNA repair genes or senescence can cause premature aging disease. Therapeutic approaches limiting DNA damage or senescence contribute to a rescued phenotype of longevity and neuroprotection, thus suggesting a mechanistic interaction between DNA damage and senescence. Here, we offer a unique perspective on the crosstalk between the DNA damage response pathway and senescence as well as their contribution to age-related diseases. We further summarize recent progress on the mechanisms and therapeutics of senescence, address existing challenges, and offering new insights and future directions in the senescence field.