Search Results (584)

Staphylococcus aureus, a major cause of foodborne illness globally, presents significant challenges due to its multidrug resistance and biofilm-forming capabilities. Pyruvate carboxylase (PycA), a metabolic master switch linking glycolysis and the tricarboxylic acid (TCA) cycle, is a potential target for controlling S. aureus. In this study, a pycA mutant was constructed and analyzed using phenotypic assays and proteomics to investigate its role in virulence and antimicrobial resistance. The results showed that deletion of pycA in the foodborne methicillin-resistant strain ATCC BAA1717 resulted in a 4- to 1024-fold reduction in resistance to β-lactams, aminoglycosides, and macrolides; a 23.24% impairment in biofilm formation; and a 22.32% decrease in staphyloxanthin production, a key antioxidant essential for survival in oxidative food environments. Proteomic analysis revealed downregulation of the TCA cycle, purine biosynthesis, surface adhesins (FnbA/B, SasG), and β-lactamase (BlaZ), linking PycA-mediated metabolism to phenotypes relevant to food safety. These findings underscore the importance of PycA as a metabolic regulator crucial for S. aureus resilience in food systems, suggesting novel strategies to combat foodborne staphylococcal infections through metabolic interference. Full article

Background/Objectives: Depression is frequently comorbid with obesity. We previously showed that astrocyte-mediated hyperactive ventral hippocampal glutamatergic afferents to the nucleus accumbens determined the exhibition of depression-like behaviors in obese murine models. However, it remains unclear if the metabolic disorder-induced depressive phenotypes and astrocytic maladaptation in the ventral hippocampus (vHPC) could be reversed following the amelioration of key metabolic impairments such as insulin resistance and dyslipidemia. Method: Male mice were fed a high-fat diet (HFD) for 12 weeks, followed by either continued HFD feeding (HFD/HFD group) or a switch to a standard diet for 4 weeks (HFD/SD group). Results: Results showed that HFD/HFD mice displayed not only glucose/lipid metabolic dysfunction, but also depression-like behaviors. In contrast, HFD/SD mice showed improvements in metabolic disorders and depressive phenotypes. Mechanistically, dietary fat reduction restored astrocyte morphology and glutamate transporter expression (GLT-1, GLAST) in the vHPC and suppressed neuroinflammatory signaling, as evidenced by reduced levels of phospho-IKK, TNF-α, IL-1β, and IL-6 in the vHPC. Conclusions: These findings suggest that dietary fat reduction reverses obesity-induced depressive phenotypes, astrocytic deficits, at least in part via suppression of neuroinflammation through the NF-κB signaling pathway. Full article

Background: Tumor-associated macrophages (TAMs) play a crucial role in the tumor microenvironment (TME), and the metabolic activities of both tumor cells and TAMs have an impact on the TME. Moreover, the expression of MICA in tumor cells is closely associated with immune cells in hepatocellular carcinoma (HCC). However, it remains unclear whether MICA expression correlates with TAMs and influences the switch in macrophage phenotype by mediating metabolic alterations. Methods: Various biostatistical tools, qPCR, and IHC staining experiments were utilized to analyze data from The Cancer Genome Atlas (TCGA) and collected HCC tumor tissues. Single-cell RNA sequencing (scRNA-seq) analyses and a co-culture model of HCC cells with macrophages were performed to validate the findings from the biostatistical analyses. Results: Through the intersection of differentially expressed genes (DEGs), metabolism-related genes (MRGs), and co-expression genes (CEGs) with MICA in HCC, the EHHADH gene was identified. Gene set enrichment analyses were conducted to further confirm the role of EHHADH. EHHADH expression is decreased in HCC tumors and can serve as a prognostic biomarker for HCC. Expressions of MICA and EHHADH exhibited significant correlations with various phenotypic macrophages and exerted opposing effects on M1-like and M2-like macrophages infiltrating HCC. The underlying metabolic and molecular mechanisms revealed that MICA in tumor cells induced M2-like polarization through the PPAR/EHHADH pathway, which regulates the fatty acid oxidation (FAO) in macrophages. Conclusions: The metabolic gene EHHADH, which is associated with MICA, led to alterations in M2-like macrophages by promoting heightened fatty acid uptake and augmenting levels of FAO within macrophages. Full article

Atherosclerosis is a chronic inflammatory disease and a major pathological basis of numerous cardiovascular conditions, with a high global mortality rate. Macrophages play a pivotal role in its pathogenesis through phenotypic switching and foam cell formation. Prostaglandin E2 receptor subtype 4 (EP4) highly expressed on the macrophage surface, is involved in various pathophysiological processes, such as inflammation and lipid metabolism. However, the role of macrophage EP4 in the progression of atherosclerosis remains unclear. To determine whether macrophage EP4 affects the progression of atherosclerosis by regulating foam cell formation and macrophage polarization. Myeloid-specific EP4 knockout mice with an ApoE-deficient background were fed a Western diet for 16 weeks. Our results showed that EP4 expression was significantly downregulated during atherosclerosis. EP4 deficiency was found to exacerbate atherosclerotic plaque formation and destabilizes plaques. In vitro studies further demonstrated that loss of EP4 in myeloid cells promoted foam cell formation and M1 macrophage polarization. Both transcriptomic and proteomic analysis showed that EP4 may regulate these processes by regulating CD36 expression in macrophage, which was further confirmed by Western blot and qPCR. In summary, deficiency of EP4 receptor in macrophages enhance foam cell formation and M1 polarization by upregulating CD36 expression, thereby accelerating the progression of atherosclerosis. Full article

Lymphotoxin-alpha (LTα3) is a soluble cytokine of the TNF superfamily. Its role in inflammation and arthritis is not well known. Macrophages are important in K/BxN Serum-Transfer Arthritis (STA) and rheumatoid arthritis (RA). Anti-TNF monoclonal antibodies as well as etanercept (ETA), a soluble TNF receptor II that also neutralizes LTα3, are efficient in the treatment of RA. Objectives: To evaluate the role of LTα3 in macrophage phenotypes and in arthritis. Methods: Macrophages were cultured in the presence of recombinant LTα3, and their phenotypes were studied. The clinical effect of blocking LTα3 in STA was evaluated, as well as the effect of switching from anti-TNF monoclonal antibodies to etanercept in the “ROC” register of RA patients. Results: We showed that recombinant LTα3 was capable of directing mouse and human macrophages towards a pro-inflammatory “M1” phenotype. In K/BxN STA, ETA decreased clinical score and joint swelling. Anti-LTα3 reduced arthritis only in TNF-KO mice, indicating that the effect of LTα3 was visible in the absence of TNF. The “ROC” register indicated that switching anti-TNF mAb to ETA did not induce clinical and biological improvement in RA. Conclusion: We show a pro-inflammatory role for LTα3 in murine and human macrophages. The neutralization of both TNF and LTα3 is not beneficial in the treatment of RA. Full article

Endothelial-to-mesenchymal transition (EndMT) is a dynamic cellular process characterized by a phenotypic-functional switch of cells from endothelial-to-mesenchymal traits. Many studies have identified EndMT as a key driver of tumor growth and progression. EndMT supports tumor cell proliferation by creating a tumor microenvironment that facilitates cancer cell survival. Notably, EndMT is an important source of cancer-associated fibroblasts, leads to immune dysregulation and immune escape, and supports metastasis and resistance to therapy. Hence, understanding the intricate relationship between EndMT and cancer progression offers exciting new avenues for therapeutic intervention. This review aims to describe the central role of EndMT in tumor progression, highlighting the molecular mechanisms underlying this endothelial alteration and its significant involvement at all stages of tumor progression. Full article

The AP2/ERF transcription factor ABSCISIC ACID INSENSITIVE 4 (ABI4) plays diverse roles in plant development and responses to abiotic stress. However, its potential involvement in regulating anthocyanin biosynthesis is not fully understood. In this study, three different loss-of-function abi4 alleles (abi4-1, abi4-2, and abi4-101) were employed to investigate the role of ABI4 in the regulation of anthocyanin accumulation in Arabidopsis seedlings. These abi4 mutants exhibited significantly increased anthocyanin accumulation, which was associated with elevated expression of genes involved in anthocyanin biosynthesis. HY5 (LONG HYPOCOTYL 5), a central component of photomorphogenesis, acts as a key light-regulated molecular switch. Further analysis revealed that ABI4 requires HY5 to function as a negative regulator of anthocyanin biosynthesis. Additionally, loss of ABI4 resulted in heightened light sensitivity, leading to increased light-induced chlorophyll accumulation and chloroplast development, along with upregulation of photosynthesis-related genes. Interestingly, the light-hypersensitive phenotype of abi4 mutants was partially rescued by the loss of HY5 function. Taken together, these findings demonstrate that ABI4 negatively regulates anthocyanin accumulation in Arabidopsis seedlings through a HY5-dependent light signaling pathway. Full article

Calcium (Ca²⁺) signaling is a fundamental regulatory mechanism controlling essential processes in the endothelium, vascular smooth muscle cells (VSMCs), and the extracellular matrix (ECM), including maintaining the endothelial barrier, modulation of vascular tone, and vascular remodeling. Cytosolic free Ca²⁺ concentration is tightly regulated by a balance between Ca²⁺ mobilization mechanisms, including Ca²⁺ release from the intracellular stores in the sarcoplasmic/endoplasmic reticulum and Ca²⁺ entry via voltage-dependent, transient-receptor potential, and store-operated Ca²⁺ channels, and Ca²⁺ elimination pathways including Ca²⁺ extrusion by the plasma membrane Ca²⁺-ATPase and Na⁺/Ca²⁺ exchanger and Ca²⁺ re-uptake by the sarco(endo)plasmic reticulum Ca²⁺-ATPase and the mitochondria. Some cell membranes/organelles are multifunctional and have both Ca²⁺ mobilization and Ca²⁺ removal pathways. Also, the individual Ca²⁺ handling pathways could be integrated to function in a regenerative, capacitative, cooperative, bidirectional, or reciprocal feed-forward or feed-back manner. Disruption of these pathways causes dysregulation of the Ca²⁺ signaling dynamics and leads to pathological cardiovascular conditions such as hypertension, coronary artery disease, atherosclerosis, and vascular calcification. In the endothelium, dysregulated Ca²⁺ signaling impairs nitric oxide production, reduces vasodilatory capacity, and increases vascular permeability. In VSMCs, Ca²⁺-dependent phosphorylation of the myosin light chain and Ca²⁺ sensitization by protein kinase-C (PKC) and Rho-kinase (ROCK) increase vascular tone and could lead to increased blood pressure and hypertension. Ca²⁺ activation of matrix metalloproteinases causes collagen/elastin imbalance and promotes vascular remodeling. Ca²⁺-dependent immune cell activation, leukocyte infiltration, and cholesterol accumulation by macrophages promote foam cell formation and atherosclerotic plaque progression. Chronic increases in VSMCs Ca²⁺ promote phenotypic switching to mesenchymal cells and osteogenic transformation and thereby accelerate vascular calcification and plaque instability. Emerging therapeutic strategies targeting these Ca²⁺-dependent mechanisms, including Ca²⁺ channel blockers and PKC and ROCK inhibitors, hold promise for restoring Ca²⁺ homeostasis and mitigating vascular disease progression. Full article

Melanoma is the most common type of skin cancer. Melanomas are well known for their ability to metastasize to other organs, including the lungs, liver, brain, and bones. The ability of melanoma cells to switch among different phenotypes is a key mechanism that underscores their metastatic potential. The objective of this work is to report here on the effect of calcium sulfide (CaS) dispersions in melanoma cells. Melanomas with the epithelial- and mesenchymal-like phenotypes were observed during cell culture preparation. The dose-dependent viability was explored up to slightly less than 3% per volume of cell culture. The dispersion reduced the relative percentage of melanomas with the epithelial- and mesenchymal-like phenotypes to (57 ± 5) and (55 ± 5)%, respectively, at 24 h post treatment. In contrast, the viability of normal fibroblasts treated with the dispersion or melanoma cells treated with the reactants used to prepare the dispersion remained nearly constant, with a value range of (100.0 ± 0.2)% for the control and (97 ± 4)% and (93 ± 2)% for doses as high as 2 and 3% per volume of cell culture, respectively. Fluorescence imaging measurements were consistent with the release of cytochrome c from the mitochondria and its translocation to the cell nuclei. The average expression of caspases 3 and 9 was found to be 3 and 1.4 times higher than in the corresponding melanoma control, respectively, which was consistent with intrinsic apoptosis. The response of vinculin expression was slightly different in both cell phenotypes. Vinculin was found to delocalize in the cytoplasm of treated mesenchymal melanoma cells, with a slightly higher concentration at the end of the actin fibers. A statistically significant increase (p < 0.0001) in the number of focal adhesion points (FAP) at the edge of the cell membrane–external cellular matrix (ECM) interphase was observed in post-treated melanoma that exhibited the epithelial-like phenotype. The changes in vinculin expression and FAP and the reduced viability of the melanomas were consistent with regulation of proteins associated with programmed cell death. It is thus proposed that the sulfides produced from the reactions of the nanoclusters in the acidic environment facilitate the regulation of proteins required to initiate apoptosis, although other processes may also be involved. We conclude that CaS may be an adequate chemical to selectively reduce melanoma viability with little effect on benign fibroblasts. Full article

Cancer stem cells (CSCs) are a subpopulation with self-renewal and differentiation capacities believed to be responsible for tumor initiation, progression, and recurrence. These cells exhibit unique metabolic features that contribute to their stemness and survival in hostile tumor microenvironments. Like non-stem cancer cells, CSCs primarily rely on glycolysis for ATP production, akin to the Warburg effect. However, CSCs also show increased dependence on alternative metabolic pathways, such as oxidative phosphorylation (OXPHOS) and fatty acid metabolism, which provide necessary energy and building blocks for self-renewal and therapy resistance. The metabolic plasticity of CSCs enables them to adapt to fluctuating nutrient availability and hypoxic conditions within the tumor. Recent studies highlight the importance of these metabolic shifts in maintaining the CSC phenotype and promoting cancer progression. The CSC model suggests that a small, metabolically adaptable subpopulation drives tumor growth and therapy resistance. CSCs can switch between glycolysis and mitochondrial metabolism, enhancing their survival under stress and dormant states. Targeting CSC metabolism offers a promising therapeutic strategy; however, their adaptability complicates eradication. A multi-targeted approach addressing various metabolic pathways is essential for effective CSC elimination, underscoring the need for further research into specific CSC markers and mechanisms that distinguish their metabolism from normal stem cells for successful therapeutic intervention. Full article

Toxoplasma gondii is a protozoan parasite capable of establishing chronic infections, with potential reactivation in immunocompromised individuals. However, the molecular mechanisms governing tachyzoite-to-bradyzoite differentiation remain incompletely understood. Previous studies have identified AP2 transcription factors as key regulators of this developmental switch. In this study, we investigated the role of the AP2 factor AP2X-8. Immunofluorescence analysis revealed that AP2X-8 is constitutively expressed in the nucleus of both tachyzoite and bradyzoite stages. Using CRISPR-Cas9-mediated homologous recombination, we successfully generated an ap2X-8 knockout strain. Phenotypic assays including plaque formation, invasion, replication, and egress, and bradyzoite differentiation assays, were then performed to assess the impact of ap2X-8 deletion. Our analyses showed that the loss of ap2X-8 significantly impaired plaque formation and intracellular replication, while invasion and egress were unaffected. Furthermore, ap2X-8 knockout enhanced bradyzoite differentiation in vitro. Despite these changes, deletion of ap2X-8 did not alter parasite virulence in a mouse infection model. These findings demonstrate that AP2X-8 is an important regulator of T. gondii tachyzoite growth and bradyzoite differentiation, offering new insights into the parasite’s developmental regulation. Full article

Background/Objectives: Under physiological conditions, vascular smooth muscle cells (VSMCs) are in a quiescent contractile state, but under pathological conditions, such as atherosclerosis, they change their phenotype to synthetic, characterized by increased proliferation, migration, and production of an extracellular matrix. Furthermore, VSMCs can undergo calcification, switching to an osteoblast-like phenotype, contributing to plaque instability. Methods: In this study, we analyzed the phenotypic changes in VSMCs during the transition from a physiological to a pathological state, a key process in the progression of atherosclerosis, using confocal and transmission electron microscopy, real-time PCR, and intracellular calcium quantification. Results: Confocal and transmission electron microscopy revealed a prominent remodeling of the actin cytoskeleton, increasing autophagic vacuoles in synthetic VSMCs and the deposition of calcium microcrystals in calcified cells. Immunofluorescence analysis revealed differential expression of α-SMA (contractile marker) and galectin-3 (synthetic marker), confirming the phenotypic changes. Real-time PCR further validated these changes, showing upregulation of RUNX-2, a marker of osteogenic transition, in calcified VSMCs. Conclusions: This study highlights the dynamic plasticity of VSMCs and their role in atherosclerosis progression. Understanding the characteristics of these phenotypic transitions can help develop targeted therapies to mitigate vascular calcification and plaque instability, potentially countering cardiovascular disease. Full article

Chronic liver diseases are marked by persistent inflammation and can evolve into liver fibrosis, cirrhosis, and hepatocellular carcinoma. In an affected liver, hepatic stellate cells (HSCs) transition from a quiescent to an activated state and adopt a myofibroblast-like cell phenotype. While these activated cells play a role in supporting liver regeneration, they can also have detrimental effects on liver function as the disease progresses to fibrosis and cirrhosis. These findings highlight the dynamic switching between different signaling pathways involving Ras, Rho GTPases, and Notch signaling. Notably, two specific members of the Ras and Rho GTPases, Eras and Rnd3, are predominantly expressed in quiescent HSCs, while Mras and Rhoc are more abundant in their activated forms. In addition, this study highlights the critical role of cytosolic Notch1 in quiescent HSCs and Rock in activated HSCs. We hypothesize that distinct yet interdependent intracellular signaling networks regulate HSC fate decisions in two key ways: by maintaining HSC quiescence and homeostasis and by facilitating HSC activation, thereby influencing processes such as proliferation, transdifferentiation, and mesenchymal transition. The proposed signaling model, combined with specific methodological tools for maintaining HSCs in a quiescent state, will deepen our understanding of the mechanisms underlying chronic liver disease and may also pave the way for innovative therapies. These therapies could include small molecule drugs targeting Ras- and Rho-dependent pathways. Full article

Vascular diseases present a significant threat to human health worldwide. Atherosclerosis is the most prevalent vascular disease, accounting for the majority of morbidity and mortality globally. Vascular calcification is a dynamic pathological process underlying the development of atherosclerotic plaques and involves the phenotypic transformation of vascular smooth muscle cells (VSMCs) into osteogenic cells. Specifically, the phenotypic switch in VSMCs often involves modifications in gene expression due to epigenetic changes, including DNA methylation, histone modification, and non-coding RNAs. Understanding the role of these epigenetic changes in regulating the pathophysiology of vascular calcification, along with the proteins and pathways that mediate these changes, will aid in identifying new therapeutic candidates to enhance vascular health. This review discusses a comprehensive range of epigenetic modifications and their implications for vascular health and the development of vascular calcification. Full article

Thoracic aortic disease (TAD) encompasses a spectrum of life-threatening conditions, including thoracic aortic aneurysm (TAA), acute type A aortic dissection (ATAAD), and bicuspid aortic valve (BAV)-associated aortopathy. While genetic mutations are well-documented contributors, emerging evidence highlights epigenetic mechanisms as critical regulators of TAD pathogenesis. This comprehensive review explores the role of epigenetic modifications—DNA methylation, histone modifications, and microRNA (miRNA) regulation—in vascular remodeling, extracellular matrix degradation, and endothelial dysfunction. Aberrant DNA methylation patterns have been implicated in TAA and ATAAD, influencing genes responsible for vascular integrity and inflammation. Histone modifications modulate smooth muscle cell phenotype switching, impacting aneurysm progression. Additionally, dysregulated miRNA expression contributes to endothelial barrier disruption and extracellular matrix remodeling, presenting novel avenues for biomarker discovery. The reversibility of epigenetic modifications offers a promising therapeutic target, with pharmacological agents such as histone deacetylase inhibitors and miRNA-based therapies showing potential in preclinical models. This review underscores the translational potential of epigenetic biomarkers for early disease detection, risk stratification, and precision medicine approaches. Further research is needed to integrate these findings into clinical practice, paving the way for innovative diagnostic and therapeutic strategies in TAD management. Full article