Search Results (683)

Metabolic dysfunction-associated steatotic liver disease (MASLD) encompasses a range of liver conditions, from simple hepatic steatosis to its more severe inflammatory form known as metabolic dysfunction-associated steatohepatitis (MASH). Despite its growing clinical significance and association with cirrhosis and cancer, there are currently few pharmacological treatments available for MASLD, highlighting the urgent need for new therapeutic strategies. This narrative review aims to elucidate the molecular mechanisms of lipophagy in MASLD progression, emphasizing how its dysfunction contributes to hepatic steatosis and lipotoxicity. We also explore the intersection of lipophagy failure with oxidative stress and inflammation in the liver, focusing on key signaling pathways, such as mTORC1 and AMPK, and discuss the therapeutic potential of targeting these pathways by systematically reviewing the literature from PubMed, Scopus, and Google Scholar databases. Recent studies suggest that lipophagy, the selective autophagic degradation of lipid droplets, is crucial for maintaining hepatic lipid homeostasis. Indeed, some vital components of the lipophagy machinery seem to be functionally inhibited in MASLD, resulting in the accumulation of intracellular triacylglycerol (TAG), lipotoxicity, and subsequent oxidative stress, all of which contribute to disease progression. In summary, impaired lipophagy is a central pathological mechanism in MASLD, making it an important therapeutic target. A deeper understanding of these mechanisms may offer new strategic insights for combating the progression of MASLD/MASH. Full article

Background/objective: Mucosal melanoma (MM) is a poorly responsive, rare and aggressive subtype with few cases having targetable recurrent driver mutations, although Ras/MAPK and PI3K/AKT/mTOR signaling pathway activations are common. Eventual tumor evasion of targeted therapy continues to limit treatment success. Adequate models are necessary to address therapeutic resistance. The relatively greater incidence of naturally occurring MM in dogs, as well as its comparable clinical and pathological characteristics to human MM, represents an opportunity for study as a human MM patient surrogate. Resistance-promoting crosstalk between Ras/MAPK and PI3K/AKT/mTOR signaling under trametinib inhibition of MEK was studied in canine MM. Emphasis was placed on the suppressive effect of trametinib on cell cycle entry and its potential role in drug resistance. Methods: D-type cyclins were investigated following trametinib treatment of five MM cell lines exhibiting differential drug sensitivities. Signaling pathway activation, proliferation, survival, cell death, and cell cycle were analyzed in the context of D-type cyclin expression. Cyclin D2 expression was manipulated using siRNA knockdown or inducible recombinant overexpression. Results: Trametinib diminished cyclin D1 in all cell lines. While relatively trametinib-resistant MM cells exhibited capacity to upregulate cyclin D2, which promoted proliferation, sensitive MM cells lacked similar cyclin D2 compensation. Inhibition of the compensatory cyclin D2 in resistant cells conferred sensitivity. Induced cyclin D2 overexpression in otherwise trametinib-sensitive MM cells promoted survival. Upregulated PI3K/AKT/mTOR signaling under trametinib treatment was suppressed by mTORC1/2 inhibition, which similarly diminished cyclin D2 response. Conclusions: The compensatory switch from preferential reliance on cyclin D1 to D2 plays a role in MM resistance to MEK inhibition. Full article

Diabetes is a risk factor for periodontitis. Increasing evidence suggests that a central player in this link is the vacuolar H+-ATPase (V-ATPase), which provides a physical and functional core for regulation by the catabolic lysosomal AMP-activated protein kinase complex (L-AMPK) and the anabolic mammalian target of rapamycin complex 1 (mTORC1). These complexes detect levels of various cellular nutrients, including glucose at the lysosome, and promote cellular responses to restore homeostasis. The high-glucose conditions of diabetes foster anabolic mTORC1 signaling that increases inflammation and inflammatory bone resorption in response to periodontal infections. Here, we review the structure and composition of V-ATPase, L-AMPK, mTORC1, and other elements of the energy-sensing platform. Mechanisms by which V-ATPase passes signals to the complexes are examined and recent data are reviewed. Current anti-bone resorptive therapeutics, bisphosphonates and denosumab, enhance the risk of medicine-related osteonecrosis of the jaw (MRONJ) and are not used to treat periodontal bone loss. Accumulating data suggest that it may be possible to target inflammatory bone resorption through agents that stimulate L-AMPK, including metformin and glucagon-like peptide-1 agonists. This approach may reduce inflammatory bone resorption without major effects on overall bone remodeling or increased risk of MRONJ. Full article

Dekkera bruxellensis is already known for its great biotechnological potential, part of this due to the ability to assimilate nitrate during fermentation. Despite the previous works on nitrogen metabolism in this yeast, especially regarding nitrate assimilation, the relation between this metabolism and the TOR (Target of Rapamycin) regulatory mechanism remains unexplored. This connection may reveal key regulatory mechanisms to maximize its fermentative performance and biotechnological use. Herein, we evaluated the physiological, metabolic, and gene expression profile of D. bruxellensis GDB 248 cultivated in ammonium and nitrate as nitrogen sources in the presence of TOR complex 1 (TORC1) inhibitor rapamycin. Our results showed that inhibition of the TORC1 significantly reduces cell growth and fermentative capacity, especially in nitrate media. Gene expression analysis revealed that TORC1 plays a central role in regulating genes involved in nitrate assimilation and the adaptive performance of D. bruxellensis in fermentative environments. Therefore, the regulation of nitrate assimilatory genes YNTI, YNRI, and YNI1 responds to a nitrate-dependent mechanism as well as to a TOR-dependent mechanism. These findings expand the understanding of the regulation of nitrogen metabolism in D. bruxellensis, providing valuable information that may aid in the development of future strategies for its use as an industrial yeast. Full article

Most known chemical carcinogens induce the direct activation of DNA damage, either directly or following metabolic activation. However, carcinogens do not always operate directly through genotoxic mechanisms but can do so via non-genotoxic carcinogenic (NGTxC) mechanisms. Immune dysfunction is one of these key events that NGTxCs have been shown to modify. The immune system is a first line of defence against transformed cells, with an innate immune response against cancer cells and mechanisms of immune evasion. Here, we review the key events of immune dysfunction. These include immunotoxicity, immune evasion, immune suppression and inflammatory-mediated immune responses, and the key players in the molecular disruption of immune anti-cancer molecular signalling pathways, particularly those mediated by cytokines and the Aryl hydrocarbon Receptor, in relation to the identification of NGTxC. The plasticity of cytokines towards functional flexibility in response to environmental stressors is also discussed from an evolutionary heritage perspective. This is combined with a critical assessment of the suitability for the regulatory application of currently available test method tools and is corroborated by the key biomarkers of, e.g., MAPK, mTOR, PD-L1, TIL and Tregs, CD8+, FoxP3+, WNT, IL-17, IL-11, IL-10, and TNFα, as identified from robust cancer biopsy studies. Finally, an understanding of how to address these endpoints for chemical hazard regulatory purposes, within an integrated approach to testing and assessment for NGTxC, is proposed. Full article

Muscle atrophy, characterized by progressive loss of skeletal muscle mass and strength, remains a significant therapeutic challenge. Jakyak-gamcho-tang (JGT) is a traditional herbal formulation that has demonstrated promising muscle-protective effects; however, the key bioactive constituents and the influence of different extraction methods have not yet been fully elucidated. This study compared the muscle-protective effects of the ethanol and water extracts of JGT (JGT-E and JGT-W, respectively), while also identifying the principal bioactive compounds that contribute to the enhanced efficacy of JGT-E. An integrative methodological approach was adopted, incorporating transcriptomic profiling, network pharmacology analysis, antioxidant activity assays, and in vitro validation using C2C12 myoblasts and myotubes. This comprehensive investigation enabled a detailed assessment of the biological activities of both JGT-E and JGT-W. Transcriptomic analysis revealed that JGT-E significantly modulates key pathways involved in oxidative phosphorylation, mitochondrial biogenesis, and signaling cascades related to PGC-1α, mTORC1, and ERRα, while simultaneously inhibiting TGF-β-mediated muscle atrophic signaling. Functional assays demonstrated that under oxidative stress conditions, JGT-E preserved mitochondrial content more effectively, reduced reactive oxygen species levels, and enhanced both myoblast viability and myotube integrity. Network pharmacology analysis identified isoliquiritigenin, catechin, and glabridin as major bioactive compounds enriched in JGT-E, all of which play critical roles in mitigating oxidative stress and supporting mitochondrial function. These findings were further substantiated by antioxidant assays that confirmed the contribution of these compounds to the observed muscle-protective effects of JGT-E. Overall, JGT-E exhibited superior efficacy in preventing muscle atrophy compared to JGT-W, likely due to its enriched profile of potent bioactive constituents. These results highlight the critical role of extraction methods in herbal medicine research and support the potential of JGT-E as a promising candidate for the treatment of muscle atrophy. Full article

The mechanistic target of the Rapamycin complex 1 (mTORC1) signaling pathway plays a pivotal role in regulating crucial life processes, including cell growth and proliferation, by sensing and integrating various signals, such as growth factors, energy status, and amino acids. Our previous studies showed that activation of the mTORC1 signaling pathway enhances silk protein synthesis and silk gland size. Here, the potential of the molecular mechanism mTORC1 to regulate the growth and development of silk gland cells was investigated. Inhibiting mTORC1 with rapamycin decreased proliferation in the Bombyx mori embryonic (BmE) cells and endoreplication in silk gland cells, reducing CyclinB and CyclinE protein levels and DNA content, and arresting the BmE cell cycle at G2/M. Conversely, the overexpression of Ras homolog enriched in brain (Rheb) led to increased proliferation of BmE cells and endoreplication in silk gland cells, as well as a significant elevation in DNA content. This study provides a molecular explanation for the increase in silk protein synthesis and silk gland length through the activation of mTORC1, thereby refining the regulatory network of the silkworm endoreplication and providing new molecular targets for breeding high-yield varieties of Bombyx mori. Full article

Humans are continuously exposed to blue light from sunlight, computers, and smartphones. While blue light has been reported to affect living organisms, its role in fat synthesis and weight changes remains unclear. In this study, we investigated the effects of prolonged blue light exposure on weight changes in mice and the protective role of tranexamic acid (TA). Mice were exposed daily to blue light from a light-emitting diode for five months. Blue light exposure led to increased fat mass and body weight. The expression of the clock genes arnt-like 1 (Bmal1) and Clock was reduced in the brain and muscle of exposed mice. In addition, reduced Sirt1 and increased mammalian target of rapamycin complex 1 (mTORC1)/sterol regulatory element-binding protein 1 (SREBP1) were observed. The levels of liver X receptor a and liver kinase B1/5′AMP-activated protein kinase a1, both involved in SREBP1-mediated lipogenesis, were also elevated. TA treatment prevented the blue light-induced suppression of Bmal1/Clock and modulated the subsequent series of signal transduction. These findings suggest that prolonged blue light exposure suppresses the clock gene Bmal1/Clock, reduces Sirt1, and activates lipogenic pathways, contributing to weight gain. TA appears to regulate clock gene expression and mitigate blue light-induced weight gain. Full article

Activation of cGAS, a cytosolic receptor recognizing double-stranded DNA, in macrophages is important in sepsis (a life-threatening condition caused by infection). The responses against sepsis induced by subcutaneous implantation of the Pseudomonas-contaminated catheters in cGAS-deficient (cGAS^−/−) mice were lower than in wild-type (WT) mice as indicated by liver enzymes, white blood cell count, cytokines, and M1-polarized macrophages in the spleens. Likewise, a lethal dose of lipopolysaccharide (LPS) induced less severe sepsis severity as determined by mortality, organ injury, cell-free DNA, and serum cytokines. Patterns of the transcriptome of lipopolysaccharide (LPS)-stimulated bone marrow-derived macrophages were clearly different between cGAS^−/− and WT cells. Gene set enrichment analysis (GSEA; a computational statistical determination of the gene set) indicated more prominent enrichment of oxidative phosphorylation (OXPHOS; the mitochondrial function) and mTORC1 pathways in LPS-activated cGAS^−/− macrophages compared with WT. Meanwhile, LPS upregulated cGAS and increased cGAMP (a cGAS inducer) only in WT macrophages along with less severe inflammation in cGAS^−/− macrophages, as indicated by supernatant cytokines, pro-inflammatory molecules (nuclear factor kappa B; NF-κB), M1 polarization (IL-1β, CD80, and CD86), and macrophage extracellular traps (METs; web-like structures composed of DNA, histones, and other proteins) through the detection of citrullinated histone 3 (CitH3) in supernatant and immunofluorescent visualization. In conclusion, less prominent pro-inflammatory responses of cGAS^−/− macrophages than WT were demonstrated in mice (catheter-induced sepsis and LPS injection model) and in vitro (transcriptomic analysis, macrophage polarization, and METs). Full article

As a chronic inflammatory disease, atherosclerosis can affect the occurrence of skeletal muscle autophagy through a variety of mechanisms. Previous studies have demonstrated that exercise enhances autophagic activity through irisin-mediated pathways. Building upon this evidence, this study investigated the effects of a 12-week aerobic exercise training on irisin levels and skeletal muscle autophagy-related proteins in atherosclerotic mice. Male C57BL/6J and ApoE^−/− mice were randomly assigned to four groups: Control Group (C), Aerobic Exercise Group (CE), ApoE^−/− Control Group (AC), and ApoE^−/− Aerobic Exercise Group (AE). Serum and muscle irisin levels were measured by ELISA; the expression levels of FNDC5, AMPK/mTOR pathway proteins and autophagy markers were detected by immunoblots, and muscle morphology was examined using H&E staining. Compared with the C group, the serum levels of TAG, TC, and LDL-C were higher than the AC group. Aerobic exercise increased irisin levels in skeletal muscle, upregulated the expression of LKB1 and p-AMPK, and presented an elevated LC3-II/I ratio, accompanied by reduced mTORC1 expression in CE mice. Aerobic exercise increased FNDC5 expression and irisin levels in serum and skeletal muscle, but also upregulated mTORC1 expression and reduced the LC3-II/I ratio in the AE group. Aerobic exercise enhances irisin synthesis and improves dyslipidemia in ApoE^−/− mice. However, the increased expression of the mTORC1 protein contributed to decreasing the expression of autophagy-related proteins following exercise. Full article

Age-related macular degeneration (AMD) is the leading cause of vision loss in the Western world, and it currently lacks effective therapy. It is believed that AMD initiates in the aged retinal pigment epithelium (RPE), which presents lysosomal dysfunction and oxidative stress (OxS) that ultimately leads to RPE damage and AMD progression. AMD is a complex pathology, so multitarget treatments are required to act on different pathways, presenting several challenges. In this review, we discuss the current knowledge on the pathogenesis of this disease, focusing mainly on lysosomal dysfunction and OxS. Because transcription factors regulate homeostasis, the transcription factor EB (TFEB), which controls lysosomal function and biogenesis, and the nuclear factor erythroid 2-related factor 2 (NRF2), which manages OxS, have been proposed as promising targets for disease intervention. Finally, we discuss the interplay of these pathways for a potential synergistic effect on AMD-targeted therapies, as they could change the course of today’s available treatments for AMD. Full article

Receptor-mediated endocytosis (RME) is a commonly recognized receptor internalization process of receptor degradation or recycling. However, recent studies have supported that RME is closely related to signal propagation and amplification from the plasma membrane to the cytosol. Few studies have elucidated the role of H₂O₂, a mild oxidant among reactive oxygen species (ROS) in RME and second messenger of signal propagation. In the present study, we investigated the regulatory function of H₂O₂ in early endosomes during signaling throughout receptor-mediated endocytosis. In mammalian cells with a physiological amount of H₂O₂ generated during epidermal growth factor (EGF) activation, fluorescence imaging showed that the levels of two activating phosphorylations on Ser⁴⁷³ and Thr³⁰⁸ of Akt were transiently increased in the plasma membrane, but the predominant p-Akt on Ser⁴⁷³ appeared in early endosomes. To examine the role of endosomal H₂O₂ molecules as signaling mediators of Akt activation in endosomes, we modulated endosomal H₂O₂ through the ectopic expression of an endosomal-targeting catalase (Cat-Endo). The forced removal of endosomal H₂O₂ inhibited the Akt phosphorylation on Ser⁴⁷³ but not on Thr³⁰⁸. The levels of mSIN and rictor, two components of mTORC2 that work as a kinase in Akt phosphorylation on Ser⁴⁷³, were also selectively diminished in the early endosomes of Cat-Endo-expressing cells. We also observed a decrease in the endosomal level of the adaptor protein containing the PH domain, the PTB domain, and the Leucine zipper motif 1 (APPL1) protein, which is an effector of Rab5 and key player in the assembly of signaling complexes regulating the Akt pathway in Cat-Endo-expressing cells compared with those in normal cells. Therefore, the H₂O₂-dependent recruitment of the APPL1 adaptor protein into endosomes was required for full Akt activation. We proposed that endosomal H₂O₂ is a promoter of Akt signaling. Full article

Background/Objectives: Chondrosarcoma (CS), the most common malignant bone tumor in adults, exhibits a poor prognosis due to high rates of post-surgical recurrence and metastasis, and resistance to chemotherapy. CS’s abundant expression of aspartyl-asparaginyl-β-hydroxylase (ASPH), which drives invasive tumor growth via Notch and PI3K/mTOR activation, opens opportunities for treatment in combination with standard Doxorubicin (DOX) chemotherapy. We hypothesized that the small molecule inhibitor SMI1182, which targets the catalytic domain of ASPH, and BEZ235, which targets PI3K/mTOR, could enhance the chemotherapeutic effects of DOX. Human CS1 (Grade 3) and CDS11 (Grade 2) conventional CS cell lines were treated with broad dose ranges of DOX, BEZ235, or SMI1182 as mono- or combination therapy to assess their anti-tumor effects on cell viability, toxicity, and motility. Methods: Mechanistic studies included the analysis of ASPH expression, Notch signaling, and insulin/IGF/IRS pathway activation through mTOR. DOX, BEZ235, or SMI1182 treatments caused dose-dependent cell loss and cytotoxicity. Results: SMI1182 and BEZ235, with or without DOX, significantly reduced directional motility. Combined treatments had additive cytotoxic effects linked to the reduced expression of ASPH, Notch transcription factors, and insulin receptor substrate type I, which positively regulates both ASPH and Notch. Conclusions: Triple-drug treatment with DOX, SMI1182, and BEZ235 could potentially improve disease-free survival with CS by the simultaneous targeting of multiple upstream mediators of aggressive malignant tumor cell behavior. Full article

Quantitative phosphoproteomics enables the comprehensive analysis of signaling pathways driven by overexpressed cancer receptors, revealing the molecular mechanisms that underpin tumor progression and therapy resistance. The glycoprotein L1 cell adhesion molecule (L1CAM) is overexpressed in high-grade serous ovarian carcinoma (HGSOC) and plays a crucial role in carcinogenesis by regulating cancer stem cell properties. Here, CRISPR–Cas9-mediated knockout of L1CAM in ovarian cancer OVCAR8 and OVCAR4 cells significantly impaired anchor-independent growth in soft agar assays and reduced clonogenic survival following external beam irradiation. In vivo, L1CAM knockout decreased cancer stem cell frequency and significantly decreased tumorigenicity. To uncover L1CAM-regulated signaling networks, we employed quantitative phosphoproteomics and proteomics. Bioinformatics analyses and validation studies revealed L1CAM-associated pathways that contribute to radioresistance through DNA repair processes and mammalian target or rapamycin complex 1 (mTORC1)-mediated signaling. In conclusion, our study established a link between L1CAM-dependent tumorigenesis and radioresistance, both hallmarks of cancer stemness, with phosphorylation of key proteins involved in DNA damage response. This study further emphasizes the value of quantitative phosphoproteomics in cancer research, showcasing its ability to enhance understanding of cancer progression and therapy resistance. Full article

Malnutrition and aging are major factors that inhibit myoblast differentiation, leading to a decline in muscle function and contributing to sarcopenia development. This study aimed to elucidate the role of nutrients in myoblast differentiation by establishing a culture system at physiological glucose levels and investigating the effects of ketone bodies and oxaloacetate. We successfully cultured myoblasts at physiological glucose concentrations in a hydrophobic membrane filter-equipped culture flask. Under these conditions, ketone bodies and oxaloacetate synergistically upregulated myogenic differentiation markers (Lmod2 and Ckm), indicating enhanced differentiation. Additionally, oxaloacetate upregulated mitochondrial biogenesis markers (mitochondrial DNA copy number and Cs), whereas ketone bodies promoted Akt phosphorylation, a key regulator of differentiation, via the PI3K/Akt/mTOR pathway. These results suggest that the intake of ketone bodies and oxaloacetate effectively prevents sarcopenia by synergistically promoting myoblast differentiation via distinct molecular mechanisms, suggesting a potential new nutritional strategy. Full article