CDDP-induced desmoplasia-like changes in oral cancer tissues are related to SASP-related factors induced by the senescence of cancer cells.

The tumor microenvironment (TME) concept has been proposed and is currently being actively studied. The development of extracellular matrix (ECM) in the TME is known as desmoplasia and is observed in many solid tumors. It has also been strongly associated with poor prognosis and resistance to drug therapy. Recently, cellular senescence has gained attention as an effect of drug therapy on cancer cells. Cellular senescence is a phenomenon wherein proliferating cells become resistant to growth-promoting stimuli, secrete the SASP (senescence-associated phenotypic) factors, and stably arrest the cell cycle. These proteins are rich in pro-inflammatory factors, such as interleukin (IL)-6, IL-8, C-X-C motif chemokine ligand 1, C-C motif chemokine ligand (CCL)2, CCL5, and matrix metalloproteinase 3. This study aimed to investigate the desmoplasia-like changes in the TME before and after cancer drug therapy in oral squamous cell carcinomas, evaluate the effect of anticancer drugs on the TME, and the potential involvement of cancer cell senescence. Using a syngeneic oral cancer transplant mouse model, we confirmed that cis-diamminedichloroplatinum (II) (CDDP) administration caused desmoplasia-like changes in cancer tissues. Furthermore, CDDP treatment-induced senescence in tumor-bearing mouse tumor tissues and cultured cancer cells. These results suggest CDDP administration-induced desmoplasia-like structural changes in the TME are related to cellular senescence. Our findings suggest that the administration of anticancer drugs alters the TME of oral cancer cells. Additionally, oral cancer cells undergo senescence, which may influence the TME through the production of SASP factors.

Diverse responses of surface biogeophysical parameters to accelerated development and senescence of vegetation on the Mongolian Plateau.

Vegetation dynamics is essential for characterizing surface biogeophysical parameters. Speeds of vegetation development and senescence are well documented, however, the effects of vegetation growth rates on surface parameters during different growth stages remains unclear. By using such methods as trend analyses and correlation analyses, this study examines the variations and interactive relationships of leaf area index (LAI) and surface parameters including Albedo, evapotranspiration (ET), and land surface temperature (LST), derived from Moderate Resolution Imaging Spectroradiometer (MODIS), during the intra-growing season (April-October, GS) on the Mongolian Plateau (MP). Generally, LAI exhibited a significant upward trend across GS months. Significant changes in VLAI (the difference in LAI between 2 consecutive months) in April-May and September-October indicated that the vegetation change rates were accelerated in the early GS (April-June) and late GS (September-October). The effect of vegetation activity on surface parameters varies over time and space. The effects of VLAI on the speed of surface parameters were inconsistent during the intra-GS. As a result of the significant changes in LAI, VET (the difference in ET between 2 consecutive months) displayed a significant upward trend during the early GS but a significant downward trend during the late GS. With acceleration of vegetation activity, the effects of VET and VAlbedo (the difference in Albedo between 2 consecutive months) on LST could offset each other at different stages of the GS. In addition, the effect of VLAI on the speed of surface parameters varied significantly by vegetation types. Our findings imply that clarifying the impact of vegetation activity on surface parameters at different growth stages can advance our understanding of vegetation responses and feedbacks to climate change.

WRKY47 transcription factor modulates leaf senescence through regulating PCD-associated genes in Arabidopsis.

Transcription factors play crucial roles in almost all physiological processes including leaf senescence. Cell death is a typical symptom appearing in senescing leaves, which is also classified as developmental programmed cell death (PCD). However, the link between PCD and leaf senescence still remains unclear. Here, we found a WRKY transcription factor WRKY47 positively modulates age-dependent leaf senescence in Arabidopsis (Arabidopsis thaliana). WRKY47 was expressed preferentially in senescing leaves. A subcellular localization assay indicated that WRKY47 was exclusively localized in nuclei. Overexpression of WRKY47 showed precocious leaf senescence, with less chlorophyll content and higher electrolyte leakage, but loss-of-function mutants of WRKY47 delayed this biological process. Through qRT-PCR and dual luciferase reporter assays, we found that WRKY47 could activate the expression of senescence-associated genes (SAGs) and PCD-associated genes to regulate leaf senescence. Furthermore, through electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP)-qPCR, WRKY47 was found to bind to W-box fragments in promoter regions of BFN1 (Bifunctional Nuclease 1) and MC6 (Metacaspase 6) directly. In general, our research revealed that WRKY47 regulates age-dependent leaf senescence by activating the transcription of two PCD-associated genes.

H2Se-evolving bio-heterojunctions promote cutaneous regeneration in infected wounds by inhibiting excessive cellular senescence.

Pathogenic infection leads to excessive senescent cell accumulation and stagnation of wound healing. To address these issues, we devise and develop a hydrogen selenide (H2Se)-evolving bio-heterojunction (bio-HJ) composed of graphene oxide (GO) and FeSe2 to deracinate bacterial infection, suppress cellular senescence and remedy recalcitrant infected wounds. Excited by near-infrared (NIR) laser, the bio-HJ exerts desired photothermal and photodynamic effects, resulting in rapid disinfection. The crafted bio-HJ could also evolve gaseous H2Se to inhibit cellular senescence and dampen inflammation. Mechanism studies reveal the anti-senescence effects of H2Se-evolving bio-HJ are mediated by selenium pathway and glutathione peroxidase 1 (GPX1). More critically, in vivo experiments authenticate that the H2Se-evolving bio-HJ could inhibit cellular senescence and potentiate wound regeneration in rats. As envisioned, our work not only furnishes the novel gasotransmitter-delivering bio-HJ for chronic infected wounds, but also gets insight into the development of anti-senescence biomaterials.

Integrated bioinformatics and validation reveal PTGS2 and its related molecules to alleviate TNF-α-induced endothelial senescence.

Accumulative evidences have indicated the interaction between cellular senescence and ferroptosis. This study intends to investigate the ferroptosis-related molecular markers in TNF-α-induced endothelial senescence. The microarray expression dataset (GSE195517) was used to identify the differently expressed ferroptosis-related genes (DEFRGs) through weighted gene co-expressed network analysis (WGCNA). GO and KEGG were performed to explore the biological function. Furthermore, hub genes were identified after protein-protein interaction (PPI) analysis and validated through real-time qPCR (RT-qPCR). Then, a drug-gene network was established to predict potential drugs for the hub genes. Seven DEFRGs were recognized in the TNF-α-induced HUVEC senescence. Moreover, four hub genes (PTGS2, TNFAIP3, CXCL2, and IL6 are upregulated) were identified by PPI analysis and validated by RT-qPCR. Further analysis exhibited that PTGS2 was subcellularly located in the plasma membrane. Furthermore, after aminosalicylic acid (ASA) was identified as ferroptosis inhibitor for targeting PTGS2 in senescent HUVECs, 5-ASA and 4-ASA were verified to alleviate TNF-α-induced HUVEC senescence through ferroptosis. PTGS2 might play a role in TNF-α-induced HUVEC senescence and ASA may be the potential drug for alleviating TNF-α-induced HUVEC senescence through ferroptosis.

K128 ubiquitination constrains RAS activity by expanding its binding interface with GAP proteins.

The RAS pathway is among the most frequently activated signaling nodes in cancer. However, the mechanisms that alter RAS activity in human pathologies are not entirely understood. The most prevalent post-translational modification within the GTPase core domain of NRAS and KRAS is ubiquitination at lysine 128 (K128), which is significantly decreased in cancer samples compared to normal tissue. Here, we found that K128 ubiquitination creates an additional binding interface for RAS GTPase-activating proteins (GAPs), NF1 and RASA1, thus increasing RAS binding to GAP proteins and promoting GAP-mediated GTP hydrolysis. Stimulation of cultured cancer cells with growth factors or cytokines transiently induces K128 ubiquitination and restricts the extent of wild-type RAS activation in a GAP-dependent manner. In KRAS mutant cells, K128 ubiquitination limits tumor growth by restricting RAL/ TBK1 signaling and negatively regulating the autocrine circuit induced by mutant KRAS. Reduction of K128 ubiquitination activates both wild-type and mutant RAS signaling and elicits a senescence-associated secretory phenotype, promoting RAS-driven pancreatic tumorigenesis.

TOR and SnRK1 signaling pathways manipulation for improving postharvest fruits and vegetables marketability.

During postharvest life, intracellular sugar insufficiency accompanied by insufficient intracellular ATP and NADPH supply, intracellular ROS overaccumulation along with intracellular ABA accumulation arising from water shortage could be responsible for accelerating fruits and vegetables deterioration through promoting SnRK1 and SnRK2 signaling pathways while preventing TOR signaling pathway. By TOR and SnRK1 signaling pathways manipulation, sufficient intracellular ATP and NADPH providing, supporting phenols, flavonoids and anthocyanins accumulation accompanied by improving DPPH, FRAP, and ABTS scavenging capacity by enhancing phenylpropanoid pathway activity, stimulating endogenous salicylic acid accumulation and NPR1-TGA-PRs signaling pathway, enhancing fatty acids biosynthesis, elongation and unsaturation, suppressing intracellular ROS overaccumulation, and promoting endogenous sucrose accumulation could be responsible for chilling injury palliating, fungal decay alleviating, senescence delaying and sensory and nutritional quality preservation in fruits and vegetables. Therefore, TOR and SnRK1 signaling pathways manipulation during postharvest shelf life by employing eco-friendly approaches such as exogenous trehalose and ATP application or engaging biotechnological approaches such as genome editing CRISPR-Cas9 or sprayable double-stranded RNA-based RNA interference would be applicable for improving fruits and vegetables marketability.

Tbxt alleviates senescence and apoptosis of nucleus pulposus cells through Atg7 mediated autophagy activation during intervertebral disc degeneration.

Intervertebral disc degeneration (IDD) is a significant cause of low back pain, characterized by excessive senescence and apoptosis of nucleus pulposus cells (NPCs). However, the precise mechanisms behind this senescence and apoptosis remains unclear. This study aimed to investigate the role of Tbxt in IDD both in vitro and in vivo, using a hydrogen peroxide (H2O2)-induced NPCs senescence and apoptosis model, as well as a rat acupuncture IDD model. Firstly, the expression of p16 and cleaved-caspase 3 significantly increased in degenerated human NPCs, accompanied by a decrease in Tbxt expression. Knockdown of Tbxt exacerbated senescence and apoptosis in the H2O2-induced NPCs degeneration model. Conversely, upregulation of Tbxt alleviated these effects induced by H2O2. Mechanistically, bioinformatic analysis revealed that the direct downstream target genes of Tbxt were highly enriched in autophagy-related pathways and overexpression of Tbxt significantly activated autophagy in NPCs. Moreover, the administration of the autophagy inhibitor, 3-methyladenine, impeded the impact of Tbxt on the processes of senescence and apoptosis in NPCs. Further investigation revealed that Tbxt enhances autophagy by facilitating the transcription of ATG7 through its interaction with a specific motif within the promoter region. In conclusion, this study suggests that Tbxt mitigates H2O2-induced senescence and apoptosis of NPCs by activating ATG7-mediated autophagy.

METTL3 promotes nucleus pulposus cell senescence in intervertebral disc degeneration by regulating TLR2 m6A methylation and gut microbiota.

BACKGROUND: Nucleus pulposus cell (NPC) senescence in intervertebral disc (IVD) tissue is the major pathological cause during intervertebral disc degeneration (IDD). N6-methyladenosine (m6A) methylation and gut microbiota play important roles in the progression of IDD. This study investigated whether methyltransferase-like 3 (METTL3) regulates TLR2 m6A modification and gut microbiota to influence NPC senescence. METHODS: An IDD rat model was established by lumbar intervertebral disc puncture and NPCs were challenged with IL-1ß to mimic IVD injury. IDD rats and IL-1ß-exposed NPCs were treated with METTL3-interfering lentivirus and the TLR2 agonist Pam3CSK4. Compositional changes in the rat gut microbiota were analyzed and fecal microbiota transplantation procedures were used. NPC senescence, cell cycle and the expression of senescence-associated secretory phenotype (SASP) factors were assessed. The m6A enrichment of TLR2 and the binding of IGF2BP1 to TLR2 mRNA were examined. RESULTS: METTL3 and TLR2 were highly expressed in IDD rats. METTL3 silencing attenuated senescent phenotypes and reduced secretion of SASP factors. Pam3CSK4 reversed the beneficial effects of METTL3 silencing on NPC senescence and IVD injury. METTL3 stabilized TLR2 mRNA in an IGF2BP1-dependent manner. METTL3 silencing restored specific gut microbiota levels in IDD rats, which was further reversed by administration of Pam3CSK4. Fecal microbiota from METTL3 silenced IDD rats altered the pathological phenotypes of IDD rats. CONCLUSIONS: These results demonstrate the beneficial effects of METTL3 silencing on NPC senescence and amelioration of IVD injury, involving modulation of TLR2 m6A modification and gut microbiota. These findings support METTL3 silencing as a potential therapeutic target for IDD.

ROS-mediated cytoplasmic localization of CARM1 induces mitochondrial fission through DRP1 methylation.

The dynamic regulation of mitochondria through fission and fusion is essential for maintaining cellular homeostasis. In this study, we discovered a role of coactivator-associated arginine methyltransferase 1 (CARM1) in mitochondrial dynamics. CARM1 methylates specific residues (R403 and R634) on dynamin-related protein 1 (DRP1). Methylated DRP1 interacts with mitochondrial fission factor (Mff) and forms self-assembly on the outer mitochondrial membrane, thereby triggering fission, reducing oxygen consumption, and increasing reactive oxygen species (ROS) production. This sets in motion a feedback loop that facilitates the translocation of CARM1 from the nucleus to the cytoplasm, enhancing DRP1 methylation and ROS production through mitochondrial fragmentation. Consequently, ROS reinforces the CARM1-DRP1-ROS axis, resulting in cellular senescence. Depletion of CARM1 or DRP1 impedes cellular senescence by reducing ROS accumulation. The uncovering of the above-described mechanism fills a missing piece in the vicious cycle of ROS-induced senescence and contributes to a better understanding of the aging process.

Inhibition of Mettl3 ameliorates osteoblastic senescence by mitigating m6A modifications on Slc1a5 via Igf2bp2-dependent mechanisms.

Age-related osteoporosis is characterized by a marked decrease in the number of osteoblasts, which has been partly attributed to the senescence of cells of the osteoblastic lineage. Epigenetic studies have provided new insights into the mechanisms of current osteoporosis treatments and bone repair pathophysiology. N6-methyladenosine (m6A) is a novel transcript modification that plays a major role in cellular senescence and is essential for skeletal development and internal environmental stability. Bioinformatics analysis revealed that the expression of the m6A reading protein Igf2bp2 was significantly higher in osteoporosis patients. However, the role of Igf2bp2 in osteoblast senescence has not been elucidated. In this study, we found that Igf2bp2 levels are increased in ageing osteoblasts induced by multiple repetition and H2O2. Increasing Igf2bp2 expression promotes osteoblast senescence by increasing the stability of Slc1a5 mRNA and inhibiting cell cycle progression. Additionally, Mettl3 was identified as Slc1a5 m6A-methylated protein with increased m6A modification. The knockdown of Mettl3 in osteoblasts inhibits the reduction of senescence, whereas the overexpression of Mettl3 promotes the senescence of osteoblasts. We found that administering Cpd-564, a specific inhibitor of Mettl3, induced increased bone mass and decreased bone marrow fat accumulation in aged rats. Notably, in an OVX rat model, Igf2bp2 small interfering RNA delivery also induced an increase in bone mass and decreased fat accumulation in the bone marrow. In conclusion, our study demonstrated that the Mettl3/Igf2bp2-Slc1a5 axis plays a key role in the promotion of osteoblast senescence and age-related bone loss.

Exploring SSEA3 as an emerging biomarker for assessing the regenerative potential of dental pulp-derived stem cells.

Background: Human dental pulp-derived stem cells (hDPSCs) have emerged as a promising source for adult stem cell-based regenerative medicine. Stage-specific embryonic antigen 3 (SSEA3) is a cell surface marker associated with Multilineage-differentiating stress-enduring (Muse) cells, a subpopulation of human bone marrow-derived stem cells (hBMSCs), known for their potent regenerative potential and safety profile. In this study, we investigated the influence of the prolonged culture period and the number of culture passages on the regenerative capacity of hDPSCs and explored the association between SSEA3 expression and their regenerative abilities. Methods: hDPSCs were isolated and cultured for up to 20 passages. Cell proliferation, migration, and osteogenic, adipogenic and neurogenic differentiation potential were assessed at passages 5, 10, and 20. Flow cytometry and immunofluorescence were employed to analyze SSEA3 expression. RNA sequencing (RNA-seq) was performed on SSEA3-positive and SSEA3-negative hDPSCs to identify differentially expressed genes and associated pathways. Results: Our findings demonstrated a progressive decline in hDPSCs proliferation and migration capacity with increasing passage number. Conversely, cell size exhibited a positive correlation with passage number. Early passage hDPSCs displayed superior osteogenic and adipogenic differentiation potential. Notably, SSEA3 expression exhibited a significant negative correlation with passage numbers, reflecting the observed decline in differentiation capacity. RNA-seq analysis revealed distinct transcriptional profiles between SSEA3-positive and SSEA3-negative hDPSCs. SSEA3-positive cells displayed upregulation of genes associated with ectodermal differentiation and downregulation of genes involved in cell adhesion. Conclusions: This study elucidates the impact of passaging on hDPSC behavior and suggests SSEA3 as a valuable biomarker for evaluating stemness and regenerative potential. SSEA3-positive hDPSCs, functionally analogous to Muse cells, represent a promising cell population for developing targeted regenerative therapies with potentially improved clinical outcomes.

Cobalt ions induce a cellular senescence secretory phenotype in human synovial fibroblast-like cells that may be an early event in the development of adverse local tissue reactions to hip implants.

Objectives: Total hip arthroplasty is a successful procedure for treating advanced osteoarthritis (OA). Metal bearing surfaces remain one of the most widely implanted prosthesis, however approximately 10% of patients develop adverse local tissue reactions (ALTRs), namely lymphocytic predominant soft tissue reaction with or without necrosis and osteolysis resulting in high revision rates. The mechanism(s) for these reactions remains unclear although T lymphocyte mediated type IV hypersensitivity to cobalt (Co) and chromium (Cr) ions have been described. The purpose of this study was to determine the prolonged effects of Co and Cr metal ions on synovial fibroblasts to better understand the impact of the synovial membrane in the development of ALTRs. Methods: Human synovial fibroblast-like cells were isolated from donors undergoing arthroplasty. DNA content and Alamar blue assay were used to determine cellular viability against exposure to Co and Cr. A beta-galactosidase assay was used to determine the development of cellular senescence. Western blotting and RT-qPCR were employed to determine changes in senescent associated secretory factors, signaling and anti-oxidant enzyme expression. A fluorescent assay was used to measure accumulation of hydrogen peroxide. Results: We demonstrate that prolonged cobalt exposure results in a downregulation of the enzyme catalase resulting in cytosolic accumulation of hydrogen peroxide, decreased Akt activity and cellular senescence. Senescent fibroblasts demonstrated upregulation of proinflammatory cytokines IL-1ß and TNFα in addition to the neurotrophic factor NGF. Conclusion: Our results provide evidence that metal ions induce a senescent associated secretory phenotype in synovial fibroblasts that could contribute to the development of adverse local tissue reactions.

Neratinib stimulates senescence of mammary cancer cells by reducing the levels of SIRT1.

Neratinib, a typical small-molecule, pan-human tyrosine kinase inhibitor (TKI), has been licensed for the treatment of human epidermal growth factor receptor 2 (HER2)-positive breast cancer. However, the underlying pharmacological mechanism is still unknown. In the current study, we report a novel function of Neratinib by showing that its treatment stimulates senescence of the mammary cancer AU565 cells. Our results demonstrate that Neratinib induces mitochondrial injury by increasing mitochondrial reactive oxygen species (ROS) and reducing intracellular adenosine triphosphate (ATP). Also, we found that Neratinib induced DNA damage by increasing the levels of 8-Hydroxy-desoxyguanosine (8-OHdG) and γH2AX in AU565 cells. Additionally, Neratinib reduced the levels of telomerase activity after 7 and 14 days incubation. Importantly, the senescence-associated-ß-galactosidase (SA-ß-Gal) assay revealed that Neratinib stimulated senescence of AU565 cells. Neratinib decreased the gene levels of human telomerase reverse transcriptase (hTERT) but increased those of telomeric repeat-binding factor 2 (TERF2) in AU565 cells. Further study displayed that Neratinib upregulated the expression of K382 acetylation of p53 (ac-K382) and p21 but reduced the levels of sirtuin-1 (SIRT1). However, overexpression of SIRT1 abolished the effects of Neratinib in cellular senescence. These findings provide strong preclinical evidence of Neratinib's treatment of breast cancer.

The protective effects of orexin-A in alleviating cell senescence against interleukin-1ß (IL-1ß) in chondrocytes.

Osteoarthritis (OA) is one of the most important causes of global disability, and dysfunction of chondrocytes is an important risk factor. The treatment of OA is still a challenge. Orexin-A is a hypothalamic peptide, and its effects in OA are unknown. In this study, we found that exposure to interleukin-1ß (IL-1ß) reduced the expression of orexin-2R, the receptor of orexin-A in TC-28a2 chondrocytes. Importantly, the senescence-associated ß-galactosidase (SA-ß-gal) staining assay demonstrated that orexin-A treatment ameliorates IL-1ß-induced cellular senescence. Importantly, the presence of IL-1ß significantly reduced the telomerase activity of TC-28a2 chondrocytes, which was rescued by orexin-A. We also found that orexin-A prevented IL-1ß-induced increase in the levels of Acetyl-p53 and the expression of p21. It is shown that orexin-A mitigates IL-1ß-induced reduction of sirtuin 3 (SIRT3). Silencing of SIRT3 abolished the protective effects of orexin-A against IL-1ß-induced cellular senescence. These results imply that orexin-A might serve as a promising therapeutic agent for OA.

Resveratrol Alleviates Arsenic Exposure-Induced Liver Fibrosis in Rats by Inhibiting Hepatocyte Senescence.

Arsenic is an environmental pollutant that has garnered considerable attention from the World Health Organization. Liver fibrosis is an advanced pathological stage of liver injury that can be caused by chronic arsenic exposure and has the potential to be reversed to prevent cirrhosis and hepatic malignancies. However, effective treatment options are currently limited. Given the profibrogenic effect of hepatocyte senescence, we established a rat model of sub-chronic sodium arsenite exposure and investigated the ability of resveratrol (RSV), a potential anti-senescence agent, to ameliorate arsenic-induced liver fibrosis and elucidate the underlying mechanism from the perspective of hepatocyte senescence. The results demonstrated that RSV was capable of mitigating fibrosis phenotypes in rat livers, including the activation of hepatic stellate cell (HSC), the generation of extracellular matrix, and the deposition of collagen fibers in the liver vascular zone, which are all induced by arsenic exposure. Furthermore, as an activator of the longevity factor SIRT1, RSV antagonized the arsenic-induced inhibition of SIRT1 expression, thereby restoring the suppression of the senescence protein p16 by SIRT1. This prevented arsenic-induced hepatocyte senescence, manifesting as a decrease in telomere shortening and a reduction in the release of senescence-associated secretory phenotype (SASP)-related proteins. In conclusion, this study demonstrated that RSV counteracts arsenic-induced hepatocyte senescence and the release of SASP-related proteins by restoring the inhibitory effect of SIRT1 on p16, thereby suppressing the activation of fibrotic phenotypes and mitigating liver fibrosis. These findings provide new insights for understanding the mechanism of arsenic-induced liver fibrosis, and more importantly, they reveal novel potential interventional approaches.

A novel senolytic drug for pulmonary fibrosis: BTSA1 targets apoptosis of senescent myofibroblasts by activating BAX.

Idiopathic pulmonary fibrosis is a progressive and age-related disease that results from impaired lung repair following injury. Targeting senescent myofibroblasts with senolytic drugs attenuates pulmonary fibrosis, revealing a detrimental role of these cells in pulmonary fibrosis. The mechanisms underlying the occurrence and persistence of senescent myofibroblasts in fibrotic lung tissue require further clarification. In this study, we demonstrated that senescent myofibroblasts are resistant to apoptosis by upregulating the proapoptotic protein BAX and antiapoptotic protein BCL-2 and BCL-XL, leading to BAX inactivation. We further showed that high levels of inactive BAX-mediated minority mitochondrial outer membrane permeabilization (minority MOMP) promoted DNA damage and myofibroblasts senescence after insult by a sublethal stimulus. Intervention of minority MOMP via the inhibition of caspase activity by quinolyl-valyl-O-methylaspartyl-[2,6-difluorophenoxy]-methyl ketone (QVD-OPH) or BAX knockdown significantly reduced DNA damage and ultimately delayed the progression of senescence. Moreover, the BAX activator BTSA1 selectively promoted the apoptosis of senescent myofibroblasts, as BTSA1-activated BAX converted minority MOMP to complete MOMP while not injuring other cells with low levels of BAX. Furthermore, therapeutic activation of BAX with BTSA1 effectively reduced the number of senescent myofibroblasts in the lung tissue and alleviated both reversible and irreversible pulmonary fibrosis. These findings advance the understanding of apoptosis resistance and cellular senescence mechanisms in senescent myofibroblasts in pulmonary fibrosis and demonstrate a novel senolytic drug for pulmonary fibrosis treatment.

Hdac3-deficiency increases senescence-associated distention of satellite DNA and telomere-associated foci in osteoprogenitor cells.

Histone deacetylase 3 (Hdac3) is an epigenetic regulator of gene expression and interacts with skeletal transcription factors such as Runx2. We previously reported that conditional deletion of Hdac3 in Osterix-Cre recombinase-expressing osteoprogenitor cells (Hdac3 CKOOsx) caused osteopenia and increased marrow adiposity, both hallmarks of skeletal aging. We also showed that Runx2+ cells within osteogenic cultures of Hdac3-depleted bone marrow stromal cells (BMSCs) contain lipid droplets (LDs). Cellular senescence, a non-proliferative metabolically active state, is associated with increased marrow adiposity, bone loss and aging. In this study, we sought to determine if Hdac3 depleted Runx2+ pre-osteoblasts from young mice exhibit chromatin changes associated with early cellular senescence and how these events correlate with the appearance of LDs. We first confirmed that BMSCs from Hdac3 CKOOsx mice have more Runx2 + LD+ cells compared to controls under osteogenic conditions. We then measured senescence-associated distention of satellite DNA (SADS) and telomere-associated foci (TAFs) in Hdac3 CKOOsx and control BMSCs. In situ, Runx2+ cells contained more SADs per nuclei in Hdac3 CKOOsx femora than in controls. Runx2+ BMSCs from Hdac3 CKOOsx mice also contained more SADS and TAFs per nuclei than Runx2+ cells from age-matched control mice in vitro. SADs and TAFs were present at similar levels in Runx2 + LD+ cells and Runx2 + LD- cells from Hdac3 CKOOsx mice. Hdac inhibitors also increased the number of SADS in Runx2 + LD+ and Runx2 + LD- wildtype BMSCs. Senolytics reduced viable cell numbers in Hdac3 CKOOsx BMSC cultures. These data demonstrate that depletion of Hdac3 in osteochondral progenitor cells triggers LD formation and early events in cellular senescence in Runx2+ BMSCs through mutually exclusive mechanisms.

Histone deacetylase 3 (Hdac3) is an enzyme within cells that binds factors in cell nuclei like Runx2 to regulate the expression of genes and control cellular functions. Deleting Hdac3 in cells responsible for bone formation causes bone loss and increases fat in the bone marrow, both hallmarks of skeletal aging. We observed that Hdac3-deletion causes Runx2+ bone marrow stromal cells (BMSCs) to store fats in lipid droplets (LD) even though the cultures were stimulated to become bone cells. Here, we investigated whether these Runx2 + LD+ cells exhibit signs of cellular senescence, which is a zombie-like state associated with increased marrow fat, bone loss and aging. We found that Hdac3-depleted Runx2+ cells showed chromatin changes linked to early cellular senescence alongside the formation of LDs. These findings suggest that Hdac3 plays a crucial role in preventing skeletal aging via regulating both LD formation and cellular senescence in osteochondral progenitor cells.

DNA damages in hepatocytes are amended by an inflammation-driven rescue repair mechanism in chronic hepatitis B.

BACKGROUND: Our previous study has shown that intrahepatic necroinflammation favors the eliminations of HBV integration and clonal hepatocytes. Here, the effect of inflammation on host DNA damage eliminations in liver biopsy tissues from patients with chronic hepatitis B (CHB) was further investigated. METHODS: DNA damage markers, histone γ-H2AX and phosphorylated heterochromatin protein 1γ (p-HP1γ), and senescent marker p21 were detected using immunohistochemical and immunofluorescent assays in liver biopsy samples from 69 CHB patients and 12 liver cirrhosis (LC) patients. Twenty paired hepatocellular carcinoma (HCC) surgical samples were used as controls. RESULTS: Both γ-H2AX and p-HP1γ were sensitively detected in nuclear and cytoplasmic/nuclear patterns. Nuclear γ-H2AX was superior as a DNA damage marker in hepatocytes. The level of nuclear γ-H2AX in CHB, comparable to those in LC and HCC, was correlated with liver fibrosis and coexisted with the senescent marker p21. However, hepatocytes carried an alleviated level of DNA damages, which was associated with the level of cytoplasmic γ-H2AX. Cytoplasmic γ-H2AX chiefly occurred in hepatocytes near necroinflammatory foci, was correlated with liver inflammation and usually indicated the decrease or disappearance of nuclear γ-H2AX. The lack of cytoplasmic γ-H2AX together with the high level of nuclear γ-H2AX was associated with the progression from large cell changes/dysplasia to small cell changes/dysplasia. CONCLUSIONS: Hepatocytes in CHB already carry massive DNA damages and undergo cellular senescence. The DNA damages in those senescent hepatocytes are histopathologically demonstrated to be amended by a novel cytoplasmic γ-H2AX-indicated and inflammation-driven rescue repair mechanism, which may be involved in hepatocarcinogenesis if it works improperly.