Apurinic/apyrimidinic endodeoxyribonuclease 1 (APE1) promotes stress granule formation via YBX1 phosphorylation in ovarian cancer.

APE1 is an essential gene involved in DNA damage repair, the redox regulation of transcriptional factors (TFs) and RNA processing. APE1 overexpression is common in cancers and correlates with poor patient survival. Stress granules (SGs) are phase-separated cytoplasmic assemblies that cells form in response to environmental stresses. Precise regulation of SGs is pivotal to cell survival, whereas their dysregulation is increasingly linked to diseases. Whether APE1 engages in modulating SG dynamics is worthy of investigation. In this study, we demonstrate that APE1 colocalizes with SGs and promotes their formation. Through phosphoproteome profiling, we discover that APE1 significantly alters the phosphorylation landscape of ovarian cancer cells, particularly the phosphoprofile of SG proteins. Notably, APE1 promotes the phosphorylation of Y-Box binding protein 1 (YBX1) at S174 and S176, leading to enhanced SG formation and cell survival. Moreover, expression of the phosphomutant YBX1 S174/176E mimicking hyperphosphorylation in APE1-knockdown cells recovered the impaired SG formation. These findings shed light on the functional importance of APE1 in SG regulation and highlight the importance of YBX1 phosphorylation in SG dynamics.

POLM variant G312R promotes ovarian tumorigenesis through genomic instability and COL11A1-NF-κB axis.

In ovarian cancer (OC), identifying key molecular players in disease escalation and chemoresistance remains critical. Our investigation elucidates the role of the DNA polymerase mu (POLM), especially G312R mutation, in propelling oncogenesis through dual pathways. POLMG312R markedly augments the ribonucleotide insertion capability of POLM, precipitating genomic instability. In addition, our research reveals that POLMG312R perturbs collagen alpha-1 (XI) chain (COL11A1) expression-a gene that plays a key role in oncogenesis-and modulates the NF-κB signaling pathway, alters the secretion of downstream inflammatory cytokines, and promotes tumor-macrophage interactions. We illustrate a bidirectional regulatory interaction between POLM, particularly its G312R variant, and COL11A1. This interaction regulates NF-κB signaling, culminating in heightened malignancy and resistance to chemotherapy in OC cells. These insights position the POLM as a potential molecular target for OC therapy, shedding light on the intricate pathways underpinning POLM variant disease progression.NEW & NOTEWORTHY Our research reveals that POLM plays an important role in ovarian cancer development, especially the mutation G312R. We uncover the POLMG312R mutation as a driver of genomic instability in ovarian cancer via aberrant ribonucleotide incorporation. We reveal that POLMG312R upregulates COL11A1 and activates NF-κB signaling, contributing to tumor progression and chemoresistance. This study identifies the POLM-COL11A1-NF-κB axis as a novel oncogenic pathway.

The nuclear receptor REV-ERBα integrates circadian clock and energy metabolism.

The physiological processes of mammals show rhythmic changes in a 24-h cycle. Circadian rhythms are under the subtle control of the autonomous circadian clock, and dysregulation of the circadian system can lead to health problems such as metabolic disorders. REV-ERBα, a member of the nuclear receptor superfamily, is an important component of the mammalian circadian clock. REV-ERBα regulates various physiological processes, including the regulation of metabolism, inflammation and immunity as well as the circadian rhythm, making it a potential therapeutic target for metabolic syndrome, inflammatory diseases and cancers. In recent years, an array of new REV-ERBα ligands have been discovered, most of which have potential applications in the treatment of diseases. In this review, we focus on the regulatory role of nuclear receptor REV-ERBα in energy metabolism and inflammation, in order to provide new strategies for the therapy of metabolic syndrome and its related diseases.

PPARs-Orchestrated Metabolic Homeostasis in the Adipose Tissue.

It has been more than three decades since peroxisome proliferator-activated receptors (PPARs) were first discovered. Many investigations have revealed the central regulators of PPARs in lipid and glucose homeostasis in response to different nutrient conditions. PPARs have attracted much attention due to their ability to improve metabolic syndromes, and they have also been proposed as classical drug targets for the treatment of hyperlipidemia and type 2 diabetes (T2D) mellitus. In parallel, adipose tissue is known to play a unique role in the pathogenesis of insulin resistance and metabolic syndromes due to its ability to "safely" store lipids and secrete cytokines that regulate whole-body metabolism. Adipose tissue relies on a complex and subtle network of transcription factors to maintain its normal physiological function, by coordinating various molecular events, among which PPARs play distinctive and indispensable roles in adipocyte differentiation, lipid metabolism, adipokine secretion, and insulin sensitivity. In this review, we discuss the characteristics of PPARs with special emphasis on the roles of the different isotypes in adipocyte biology.

Succinylation at a key residue of FEN1 is involved in the DNA damage response to maintain genome stability.

Human flap endonuclease 1 (FEN1) is a structure-specific, multifunctional endonuclease essential for DNA replication and repair. Our previous study showed that in response to DNA damage, FEN1 interacts with the PCNA-like Rad9-Rad1-Hus1 complex instead of PCNA to engage in DNA repair activities, such as stalled DNA replication fork repair, and undergoes SUMOylation by SUMO-1. Here, we report that succinylation of FEN1 was stimulated in response to DNA replication fork-stalling agents, such as ultraviolet (UV) irradiation, hydroxyurea, camptothecin, and mitomycin C. K200 is a key succinylation site of FEN1 that is essential for gap endonuclease activity and could be suppressed by methylation and stimulated by phosphorylation to promote SUMO-1 modification. Succinylation at K200 of FEN1 promoted the interaction of FEN1 with the Rad9-Rad1-Hus1 complex to rescue stalled replication forks. Impairment of FEN1 succinylation led to the accumulation of DNA damage and heightened sensitivity to fork-stalling agents. Altogether, our findings suggest an important role of FEN1 succinylation in regulating its roles in DNA replication and repair, thus maintaining genome stability.

Brown adipose Vanin-1 is required for the maintenance of mitochondrial homeostasis and prevents diet-induced metabolic dysfunction.

BACKGROUND: Energy-dissipating brown adipocytes have significant potential for improving systemic metabolism. Vanin-1, a membrane-bound pantetheinase, is involved in various biological processes in mice. However, its role in BAT mitochondrial function is still unclear. In this study, we aimed to elucidate the impact of Vanin-1 on BAT function and contribution during overnutrition-induced obesity. METHODS: Vanin-1 expression was analyzed in different adipose depots in mice. The cellular localization of Vanin-1 was analyzed by confocal microscopy and western blots. Mice lacking Vanin-1 (Vanin-1-/-) were continuously fed either a chow diet or a high-fat diet (HFD) to establish an obesity model. RNA-seq analysis was performed to identify the molecular changes associated with Vanin-1 deficiency during obesity. BAT-specific Vanin-1 overexpression mice were established to determine the effects of Vanin-1 in vivo. Cysteamine treatment was used to examine the effect of enzymatic reaction products of Vanin-1 on BAT mitochondria function in Vanin-1-/- mice. RESULTS: The results indicate that the expression of Vanin-1 is reduced in BAT from both diet-induced and leptin-deficient obese mice. Study on the subcellular location of Vanin-1 shows that it has a mitochondrial localization. Vanin-1 deficiency results in increased adiposity, BAT dysfunction, aberrant mitochondrial structure, and promotes HFD induced-BAT whitening. This is attributed to the impairment of the electron transport chain (ETC) in mitochondria due to Vanin-1 deficiency, resulting in reduced mitochondrial respiration. Overexpression of Vanin-1 significantly enhances energy expenditure and thermogenesis in BAT, renders mice resistant to diet-induced obesity. Furthermore, treatment with cysteamine rescue the mitochondrial dysfunction in Vanin-1-/- mice. CONCLUSIONS: Collectively, these findings suggest that Vanin-1 plays a crucial role in promoting mitochondrial respiration to counteract diet-induced obesity, making it a potential therapeutic target for obesity.

Rhodiolin inhibits the PI3K/AKT/mTOR signaling pathway via the glycolytic enzyme GPI in human papillary thyroid cancer.

BACKGROUND: Papillary thyroid carcinoma (PTC) is an endocrine malignant tumor of the head and neck. Surgery and chemotherapy are PTC treatments, but have adverse effects. Exploration of new non-toxic anti-PTC drugs for PTC treatment is an unmet need. METHODS: We aimed to identify anti-PTC drugs that could inhibit PTC-cell proliferation through high-throughput screening of a library of well-characterized naturally occurring small-molecule compounds. Then, the anti-PTC function of rhodiolin was validated by in vitro cell models and xenograft tumor models RESULTS: We initially demonstrated that rhodiolin inhibited the growth and induced the apoptosis of PTC cells significantly in vitro and in vivo. At the metabolic level, rhodiolin blocked glycolysis through glucose 6-phosphate isomerase (GPI), which suggested that glycolytic inhibition may be involved in mediating the anti-PTC function of rhodiolin. Transcriptomics analysis combined with bioinformatics analysis identified rhodiolin treatment to inhibit phosphorylation of the phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) signaling pathway. Collectively, our findings demonstrated that rhodiolin inhibited the proliferation and induced the apoptosis of PTC cells by blocking glycolysis through the glycolytic enzyme GPI, thereby inhibiting phosphorylation of the PI3K/Akt/mTOR signaling pathway. CONCLUSION: Our study demonstrates the potential use of rhodiolin in inhibiting the proliferation and inducing the apoptosis of PTC cells. Inhibition of phosphorylation of the PI3K/Akt/mTOR signaling pathway mediated by GPI plays an extremely important part in the ant-PTC function of rhodiolin. These results suggest that rhodiolin is a promising drug in the treatment of PTC progression. Our results provide a novel target and cell signaling pathway for PTC therapy from the perspective of energy metabolism, which could provide new perspectives and new drug choices for PTC therapy. In addition to that, our study will help to make up for the lack of drug research for PTC.

Post-translational Modifications by Acyl Groups Regulate FEN1's Activities and Play Essential Roles in Cell Proliferation and DNA Repair.

BACKGROUND: Flap endonuclease 1 (FEN1), well known for its structural-specific nuclease, possessing 5'-flap endonuclease and 5'-3' exonuclease activities, is mainly involved in DNA replication and repair. Protein lysine acetylation is an important posttranslational modification that could regulate numerous proteins' activity, subcellular localization, protein-protein interaction etc., and influences many biological processes. Our previous studies on integrated succinylome profiles found that succinylation and acetylation levels of FEN1 would change under different conditions. Succinylation at FEN1 Lys200 site results in the accumulation of damaged DNA and increased susceptibility to fork-stalling agents. The interplay with other forms of modification could affects its protein interaction affinity and thus contribute to genome stability. OBJECTIVE: This article studied the biological role of FEN1 by acyl modification in HeLa cells. METHOD: In order to explore the function of FEN1 acylation in cells, we mimicked the presence or absence of acetylation or succinylation by mutating key amino acids to glutamic acid and glutamine. We carried out a series of experiments including cell cycle, MTS, enzyme kinetics measurements, immunofluorescence and so on. RESULTS: The absence of acylation of FEN1 leads to the blocked cell cycle process and the reduced efficiency of FEN1 on its DNA substrates, affecting the interaction of FEN1 with both repair and replication related proteins and thus its role in the repair of DNA damage. CONCLUSION: We have verified acyl groups could modify Lys125, Lys252 and Lys254 of FEN1. Acylation level of these three is important for enzyme activity, cell proliferation and DNA damage response, thus contributing to genome stability.

Various antibacterial mechanisms of biosynthesized copper oxide nanoparticles against soilborne Ralstonia solanacearum.

The substantial antimicrobial efficacy of nanoparticles against phytopathogens has been extensively investigated for advanced agricultural applications. However, few reports have focused on soilborne pathogenic bacteria. The aim of this study was to obtain sustainably synthesized copper oxide nanoparticles (CuONPs) using papaya leaf extracts and investigate the bactericidal activity of these CuONPs against Ralstonia solanacearum, the cause of bacterial wilt, under laboratory and greenhouse conditions. The results showed that CuONPs possessed strong antibacterial activity and that all R. solanacearum were killed after exposure to 250 µg mL-1 CuONPs. CuONPs could interact with bacterial cells to prevent biofilm formation, reduce swarming motility and disturb ATP production. Ultrastructural observations by transmission electron microscopy (TEM) revealed that after interactions with CuONPs, bacterial cells suffered significantly from nanomechanical damage to the cytomembrane, accompanied by the absorption of multiple nanoparticles. In addition, molecular studies identified the downregulation mechanism of a series of genes involving pathogenesis and motility. The control efficiency of CuONPs in tobacco bacterial wilt disease management under greenhouse conditions was verified by root irrigation application, demonstrating that as-prepared CuONPs significantly reduced the disease occurrence and disease index. Our studies focused on developing biosynthesized nanoparticles as a biocompatible alternative for soilborne disease management.

N 4-Cytosine DNA Methylation Is Involved in the Maintenance of Genomic Stability in Deinococcus radiodurans.

DNA methylation serves as a vital component of restriction-modification (R-M) systems in bacteria, where it plays a crucial role in defense against foreign DNA. Recent studies revealed that DNA methylation has a global impact on gene expression. Deinococcus radiodurans, an ideal model organism for studying DNA repair and genomic stability, possesses unparalleled resistance to DNA-damaging agents such as irradiation and strong oxidation. However, details on the methylome of this bacterium remain unclear. Here, we demonstrate that N 4-cytosine is the major methylated form (4mC) in D. radiodurans. A novel methylated motif, "C4mCGCGG" was identified that was fully attributed to M.DraR1 methyltransferase. M.DraR1 can specifically bind and methylate the second cytosine at N 4 atom of "CCGCGG" motif, preventing its digestion by a cognate restriction endonuclease. Cells deficient in 4mC modification displayed higher spontaneous rifampin mutation frequency and enhanced DNA recombination and transformation efficiency. And genes involved in the maintenance of genomic stability were differentially expressed in conjunction with the loss of M.DraR1. This study provides evidence that N 4-cytosine DNA methylation contributes to genomic stability of D. radiodurans and lays the foundation for further research on the mechanisms of epigenetic regulation by R-M systems in bacteria.