Genetic deficiency of the transcription factor NFAT1 confers protection against fibrogenic responses independent of immune influx.

Idiopathic pulmonary fibrosis (IPF) is marked by unremitting matrix deposition and architectural distortion. Multiple profibrotic pathways contribute to the persistent activation of mesenchymal cells (MCs) in fibrosis, highlighting the need to identify and target common signaling pathways. The transcription factor nuclear factor of activated T cells 1 (NFAT1) lies downstream of second messenger calcium signaling and has been recently shown to regulate key profibrotic mediator autotaxin (ATX) in lung MCs. Herein, we investigate the role of NFAT1 in regulating fibroproliferative responses during the development of lung fibrosis. Nfat1-/--deficient mice subjected to bleomycin injury demonstrated improved survival and protection from lung fibrosis and collagen deposition as compared with bleomycin-injured wild-type (WT) mice. Chimera mice, generated by reconstituting bone marrow cells from WT or Nfat1-/- mice into irradiated WT mice (WT→WT and Nfat1-/-→WT), demonstrated no difference in bleomycin-induced fibrosis, suggesting immune influx-independent fibroprotection in Nfat1-/- mice. Examination of lung tissue and flow sorted lineageneg/platelet-derived growth factor receptor alpha (PDGFRα)pos MCs demonstrated decreased MC numbers, proliferation [↓ cyclin D1 and 5-ethynyl-2'-deoxyuridine (EdU) incorporation], myofibroblast differentiation [↓ α-smooth muscle actin (α-SMA)], and survival (↓ Birc5) in Nfat1-/- mice. Nfat1 deficiency abrogated ATX expression in response to bleomycin in vivo and MCs derived from Nfat1-/- mice demonstrated decreased ATX expression and migration in vitro. Human IPF MCs demonstrated constitutive NFAT1 activation, and regulation of ATX in these cells by NFAT1 was confirmed using pharmacological and genetic inhibition. Our findings identify NFAT1 as a critical mediator of profibrotic processes, contributing to dysregulated lung remodeling and suggest its targeting in MCs as a potential therapeutic strategy in IPF.NEW & NOTEWORTHY Idiopathic pulmonary fibrosis (IPF) is a fatal disease with hallmarks of fibroblastic foci and exuberant matrix deposition, unknown etiology, and ineffective therapies. Several profibrotic/proinflammatory pathways are implicated in accelerating tissue remodeling toward a honeycombed end-stage disease. NFAT1 is a transcriptional factor activated in IPF tissues. Nfat1-deficient mice subjected to chronic injury are protected against fibrosis independent of immune influxes, with suppression of profibrotic mesenchymal phenotypes including proliferation, differentiation, resistance to apoptosis, and autotaxin-related migration.

Apoptosis-related prognostic biomarkers and potential targets for acute kidney injury based on machine learning algorithm and in vivo experiments.

Acute kidney injury (AKI) is a common critical illness in hospitalized patients, characterized by a rapid decline in kidney function over a short period, which can seriously endanger the patient's life. Currently, there is a lack of precise and universal AKI diagnostic biomarkers in clinical practice. In this study, weighted gene coexpression network analysis (WGCNA), differential expression analysis, univariate and multivariate logistic regression analyses, receiver operating characteristic (ROC) curves, and immune cell infiltration were performed to identify apoptosis-related biomarkers that can be used for AKI diagnosis. Three core apoptosis-related genes (ARGs), CBFB, EGF and COL1A1, were identified as AKI biomarkers. More importantly, an apoptosis-related signature containing three hub ARGs was validated as a diagnostic model. The hub genes exhibited good correlations with glomerular filtration rate (GFR) and serum creatinine (SCr) in the Nephroseq kidney disease database. Additionally, CIBERSORT immune infiltration analysis indicated that these core ARGs may affect immune cell recruitment and infiltration in AKI patients. Subsequently, we investigated the alteration of the expression levels of three core ARGs in AKI samples using single-cell RNA sequencing analysis and analyzed the cell types that mainly expressed these ARGs. More importantly, the expression of core ARGs was validated in folic acid- and cisplatin-induced AKI mouse models. In summary, our study identified three diagnostic biomarkers for AKI, explored the roles of ARGs in AKI progression and provided new ideas for the clinical diagnosis and treatment of AKI.

Transcription factors-related molecular subtypes and risk prognostic model: exploring the immunogenicity landscape and potential drug targets in hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) is the most prevalent form of liver cancer, with a high mortality rate and poor prognosis. Mutated or dysregulated transcription factors (TFs) are significantly associated with carcinogenesis. The aim of this study was to develop a TF-related prognostic risk model to predict the prognosis and guide the treatment of HCC patients. METHODS: RNA sequencing data were obtained from the TCGA database. The ICGC and GEO databases were used as validation datasets. The consensus clustering algorithm was used to classify the molecular subtypes of TFs. Kaplan‒Meier survival analysis and receiver operating characteristic (ROC) analysis were applied to evaluate the prognostic value of the model. The immunogenic landscape differences of molecular subtypes were evaluated by the TIMER and xCell algorithms. Autodock analysis was used to predict possible binding sites of trametinib to TFs. RT‒PCR was used to verify the effect of trametinib on the expression of core TFs. RESULTS: According to the differential expression of TFs, HCC samples were divided into two clusters (C1 and C2). The survival time, signaling pathways, abundance of immune cell infiltration and responses to chemotherapy and immunotherapy were significantly different between C1 and C2. Nine TFs with potential prognostic value, including HMGB2, ESR1, HMGA1, MYBL2, TCF19, E2F1, FOXM1, CENPA and ZIC2, were identified by Cox regression analysis. HCC patients in the high-risk group had a poor prognosis compared with those in the low-risk group (p < 0.001). Moreover, the area under the ROC curve (AUC) values of the 1-year, 2-year and 3-year survival rates were 0.792, 0.71 and 0.695, respectively. The risk model was validated in the ICGC database. Notably, trametinib sensitivity was highly correlated with the expression of core TFs, and molecular docking predicted the possible binding sites of trametinib with these TFs. More importantly, the expression of core TFs was downregulated under trametinib treatment. CONCLUSIONS: A prognostic signature with 9 TFs performed well in predicting the survival rate and chemotherapy/immunotherapy effect of HCC patients. Trimetinib has potential application value in HCC by targeting TFs.

Deferasirox shows inhibition activity against cervical cancer in vitro and in vivo.

OBJECTIVE: Iron depletion may be a novel therapeutic strategy for cancer. This study aimed to assess the inhibition effects of deferasirox (DFX), an oral iron chelator, on cervical cancer. METHODS: In this study, we performed immunohistochemical analysis, enzyme-linked immunoassay, cell viability and invasive ability assay, cell cycle and apoptosis analysis, protein expression investigation, molecular mechanism investigation, and in vivo murine xenograft model to evaluate the impact of DFX on cervical cancer. RESULTS: The cervical cancer cell lines viability decreased and cell apoptosis was induced after DFX incubation. Additionally, DFX promoted cell cycle arrest by regulating the expression of cell cycle regulators cyclin D1, cyclin E and proliferating cell nuclear antigen (PCNA) in cervical cancer cell lines. DFX also decreased cell invasion by upregulating the expression of NDRG1 and downregulating c-Myc. The activation of Akt and the MEK/ERK signaling pathway was inhibited by DFX. DFX also significantly suppressed xenograft tumor growth, decreased the levels of ferritin in serum and tumor tissue, reduced iron deposits and reactive oxygen species (ROS) levels in xenografts of DFX-treated group compared with the control group, with no serious side effects. CONCLUSION: Present study demonstrated the inhibitory effect of DFX against cervical cancer, and provided a potential therapeutic agent for cervical cancer.

Clioquinol Attenuates Pulmonary Fibrosis through Inactivation of Fibroblasts via Iron Chelation.

Strict control of iron homeostasis is critical for the maintenance of normal lung function. Iron accumulates in the lungs of patients with idiopathic pulmonary fibrosis (PF), but the characteristics of iron metabolism in the pathogenesis of PF and related targeting therapeutics are not well studied. In this study, we investigated the cellular and molecular characteristics of iron metabolism in fibrotic lungs and further explored the efficacy of clioquinol (CQ) for the treatment of PF as well as its functional mechanism. Iron aggregates accumulated in the lungs of patients with idiopathic PF, and FTL (ferritin light chain) transcripts were increased in their pulmonary fibroblasts. In the bleomycin (BLM)-induced PF (BLM-PF) mouse model, pulmonary iron accumulation is a very early and concomitant event of PF. Labile iron pool levels in both fibroblasts and macrophages from the BLM-PF model were elevated, and iron metabolism was dysregulated. CQ attenuated PF induced by BLM and FITC, and iron-saturated CQ did not alleviate BLM-PF. Furthermore, CQ inhibited the activation of fibroblasts, including proliferation, fibrotic differentiation, proinflammatory cytokine secretion, and migration. In conclusion, our study demonstrated that CQ, acting as an iron chelator, attenuates experimental PF through inactivation of fibroblasts, providing support for targeting iron metabolism as a basis for PF treatment.

The effect of air pollution on immunological, antioxidative and hematological parameters, and body condition of Eurasian tree sparrows.

Air pollution constitutes potential threats to wildlife and human health; therefore, it must be monitored accurately. However, little attention has been given to understanding the toxicological effects induced by air pollution and the suitability of bird species as bioindicators. The Eurasian tree sparrow (Passer montanus), a human commensal species, was used as a study model to examine toxic metal accumulation, retention of particulate matter (PM), immunological and antioxidant capacities, and hematological parameters in birds inhabiting those areas with relatively higher (Shijiazhuang city) or lower (Chengde city) levels of PM2.5 and PM10 in China. Our results showed that Shijiazhuang birds had significantly more particle retention in the lungs and toxic metal (including aluminum, arsenic, cadmium, iron, manganese, and lead) accumulation in the feathers relative to Chengde birds. They also had lower superoxide dismutase, albumin, immunoglobulin M concentrations in the lung lavage fluid, and total antioxidant capacity (T-AOC) in the lungs and hearts. Furthermore, although they had higher proportions of microcytes, hypochromia, and polychromatic erythrocytes in the peripheral blood (a symptom of anemia), both populations exhibited comparable body conditions, white cell counts, heterophil and lymphocyte ratios, and plasma T-AOC and corticosterone levels. Therefore, our results not only confirmed that Shijiazhuang birds experienced a greater burden from environmental PM and toxic metals but also identified a suite of adverse effects of environmental pollution on immunological, antioxidative, and hematological parameters in multiple tissues. These findings contribute to our understanding of the physiological health consequences induced by PM exposure in wild animals. They suggest that free-living birds inhabiting urban areas could be used as bioindicators for evaluating the adverse effects induced by environmental pollution.

Deferasirox protects against hydrogen peroxide-induced cell apoptosis by inhibiting ubiquitination and degradation of p21WAF1/CIP1.

Deferasirox (DFX) is an iron chelator approved for the treatment of iron overload diseases. However, the role of DFX in oxidative stress-induced cell apoptosis and the exact molecular mechanisms underlying these processes remain poorly understood and require further investigation. In this study, we found that DFX rendered resistant to H2O2-induced apoptosis in HEK293T cells, reduced the intracellular levels of the labile iron pool (LIP) and oxidative stress induced by H2O2. Furthermore, DFX inhibited the ubiquitination and degradation of the cyclin-dependent kinase inhibitor p21WAF1/CIP1 (p21) via modulation of the interaction of p21 with SCF-Skp2. DFX also showed the inhibition effect on the activation of c-Jun N-terminal kinase (JNK), pro-caspase-3 and related mitochondrial apoptosis pathway induced by H2O2. These results provide novel insights into the molecular mechanism underpinning iron-mediated oxidative stress and apoptosis, and they may represent a promising target for therapeutic interventions in related pathological conditions.

Latest progress on the molecular mechanisms of idiopathic pulmonary fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a serious life-threatening lung disease, and the median survival period of PF patients after diagnosis is only 2.5-3.5 years. At present, there are no effective drugs or therapeutics to reverse or even inhibit IPF. The main pathological characteristics of pulmonary fibrosis (PF) include damage to alveolar epithelial cells, fibroblast activation and extracellular matrix accumulation, which gradually lead to damage to the lung structure and decreased lung function. It is important to understand the cellular and molecular mechanisms of PF comprehensively and clearly. In this paper, critical signaling pathways related to PF were reviewed to present updates on the molecular mechanisms of PF.

Reciprocal Changes in Phosphoenolpyruvate Carboxykinase and Pyruvate Kinase with Age Are a Determinant of Aging in Caenorhabditis elegans.

Aging involves progressive loss of cellular function and integrity, presumably caused by accumulated stochastic damage to cells. Alterations in energy metabolism contribute to aging, but how energy metabolism changes with age, how these changes affect aging, and whether they can be modified to modulate aging remain unclear. In locomotory muscle of post-fertile Caenorhabditis elegans, we identified a progressive decrease in cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C), a longevity-associated metabolic enzyme, and a reciprocal increase in glycolytic pyruvate kinase (PK) that were necessary and sufficient to limit lifespan. Decline in PEPCK-C with age also led to loss of cellular function and integrity including muscle activity, and cellular senescence. Genetic and pharmacologic interventions of PEPCK-C, muscle activity, and AMPK signaling demonstrate that declines in PEPCK-C and muscle function with age interacted to limit reproductive life and lifespan via disrupted energy homeostasis. Quantifications of metabolic flux show that reciprocal changes in PEPCK-C and PK with age shunted energy metabolism toward glycolysis, reducing mitochondrial bioenergetics. Last, calorie restriction countered changes in PEPCK-C and PK with age to elicit anti-aging effects via TOR inhibition. Thus, a programmed metabolic event involving PEPCK-C and PK is a determinant of aging that can be modified to modulate aging.

Inherent instability of the retinitis pigmentosa P23H mutant opsin.

The P23H opsin mutation is the most common cause of autosomal dominant retinitis pigmentosa. Even though the pathobiology of the resulting retinal degeneration has been characterized in several animal models, its complex molecular mechanism is not well understood. Here, we expressed P23H bovine rod opsin in the nervous system of Caenorhabditis elegans. Expression was low due to enhanced protein degradation. The mutant opsin was glycosylated, but the polysaccharide size differed from that of the normal protein. Although P23H opsin aggregated in the nervous system of C. elegans, the pharmacological chaperone 9-cis-retinal stabilized it during biogenesis, producing a variant of rhodopsin called P23H isorhodopsin. In vitro, P23H isorhodopsin folded correctly, formed the appropriate disulfide bond, could be photoactivated but with reduced sensitivity, and underwent Meta II decay at a rate similar to wild type isorhodopsin. In worm neurons, P23H isorhodopsin initiated phototransduction by coupling with the endogenous Gi/o signaling cascade that induced loss of locomotion. Using pharmacological interventions affecting protein synthesis and degradation, we showed that the chromophore could be incorporated either during or after mutant protein translation. However, regeneration of P23H isorhodopsin with chromophore was significantly slower than that of wild type isorhodopsin. This effect, combined with the inherent instability of P23H rhodopsin, could lead to the structural cellular changes and photoreceptor death found in autosomal dominant retinitis pigmentosa. These results also suggest that slow regeneration of P23H rhodopsin could prevent endogenous chromophore-mediated stabilization of rhodopsin in the retina.

Isotopic labeling of mammalian G protein-coupled receptors heterologously expressed in Caenorhabditis elegans.

High-resolution structural determination and dynamic characterization of membrane proteins by nuclear magnetic resonance (NMR) require their isotopic labeling. Although a number of labeled eukaryotic membrane proteins have been successfully expressed in bacteria, they lack post-translational modifications and usually need to be refolded from inclusion bodies. This shortcoming of bacterial expression systems is particularly detrimental for the functional expression of G protein-coupled receptors (GPCRs), the largest family of drug targets, due to their inherent instability. In this work, we show that proteins expressed by a eukaryotic organism can be isotopically labeled and produced with a quality and quantity suitable for NMR characterization. Using our previously described expression system in Caenorhabditis elegans, we showed the feasibility of labeling proteins produced by these worms with (15)N,(13)C by providing them with isotopically labeled bacteria. (2)H labeling also was achieved by growing C. elegans in the presence of 70% heavy water. Bovine rhodopsin, simultaneously expressed in muscular and neuronal worm tissues, was employed as the "test" GPCR to demonstrate the viability of this approach. Although the worms' cell cycle was slightly affected by the presence of heavy isotopes, the final protein yield and quality was appropriate for NMR structural characterization.

Glycolysis and beyond in glucose metabolism: exploring pulmonary fibrosis at the metabolic crossroads.

At present, pulmonary fibrosis (PF) is a prevalent and irreversible lung disease with limited treatment options, and idiopathic pulmonary fibrosis (IPF) is one of its most common forms. Recent research has highlighted PF as a metabolic-related disease, including dysregulated iron, mitochondria, lipid, and glucose homeostasis. Systematic reports on the regulatory roles of glucose metabolism in PF are rare. This study explores the intricate relationships and signaling pathways between glucose metabolic processes and PF, delving into how key factors involved in glucose metabolism regulate PF progression, and the interplay between them. Specifically, we examined various enzymes, such as hexokinase (HK), 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3), pyruvate kinase (PK), and lactate dehydrogenase (LDH), illustrating their regulatory roles in PF. It highlights the significance of lactate, alongside the role of pyruvate dehydrogenase kinase (PDK) and glucose transporters (GLUTs) in modulating pulmonary fibrosis and glucose metabolism. Additionally, critical regulatory factors such as transforming growth factor-beta (TGF-ß), interleukin-1 beta (IL-1ß), and hypoxia-inducible factor 1 subunit alpha (HIF-1α) were discussed, demonstrating their impact on both PF and glucose metabolic pathways. It underscores the pivotal role of AMP-activated protein kinase (AMPK) in this interplay, drawing connections between diabetes mellitus, insulin, insulin-like growth factors, and peroxisome proliferator-activated receptor gamma (PPARγ) with PF. This study emphasizes the role of key enzymes, regulators, and glucose transporters in fibrogenesis, suggesting the potential of targeting glucose metabolism for the clinical diagnosis and treatment of PF, and proposing new promising avenues for future research and therapeutic development.

Heterologous expression of functional G-protein-coupled receptors in Caenorhabditis elegans.

New strategies for expression, purification, functional characterization, and structural determination of membrane-spanning G-protein-coupled receptors (GPCRs) are constantly being developed because of their importance to human health. Here, we report a Caenorhabditis elegans heterologous expression system able to produce milligram amounts of functional native and engineered GPCRs. Both bovine opsin [(b)opsin] and human adenosine A(2A) subtype receptor [(h)A(2A)R] expressed in neurons or muscles of C. elegans were localized to cell membranes. Worms expressing these GPCRs manifested changes in motor behavior in response to light and ligands, respectively. With a newly devised protocol, 0.6-1 mg of purified homogenous 9-cis-retinal-bound bovine isorhodopsin [(b)isoRho] and ligand-bound (h)A(2A)R were obtained from C. elegans from one 10-L fermentation at low cost. Purified recombinant (b)isoRho exhibited its signature absorbance spectrum and activated its cognate G-protein transducin in vitro at a rate similar to native rhodopsin (Rho) obtained from bovine retina. Generally high expression levels of 11 native and mutant GPCRs demonstrated the potential of this C. elegans system to produce milligram quantities of high-quality GPCRs and possibly other membrane proteins suitable for detailed characterization.

Light-sensitive coupling of rhodopsin and melanopsin to G(i/o) and G(q) signal transduction in Caenorhabditis elegans.

Activation of G-protein-coupled receptors (GPCRs) initiates signal transduction cascades that affect many physiological responses. The worm Caenorhabditis elegans expresses >1000 of these receptors along with their cognate heterotrimeric G proteins. Here, we report properties of 9-cis-retinal regenerated bovine opsin [(b)isoRho] and human melanopsin [(h)Mo], two light-activated, heterologously expressed GPCRs in the nervous system of C. elegans with various genetically engineered alterations. Profound transient photoactivation of G(i/o) signaling by (b)isoRho led to a sudden and transient loss of worm motility dependent on cyclic adenosine monophosphate, whereas transient photoactivation of G(q) signaling by (h)Mo enhanced worm locomotion dependent on phospholipase Cß. These transgenic C. elegans models provide a unique way to study the consequences of G(i/o) and G(q) signaling in vivo with temporal and spatial precision and, by analogy, their relationship to human neuromotor function.

Landscape analysis and overview of the literature on oxidative stress and pulmonary diseases.

Oxidative stress is caused by an imbalance in oxidant/antioxidant processes and is a critical process in pulmonary diseases. As no truly effective therapies exist for lung cancer, lung fibrosis and chronic obstructive pulmonary disease (COPD), at present, it is important to comprehensively study the relationship between oxidative stress and pulmonary diseases to identify truly effective therapeutics. Since there is no quantitative and qualitative bibliometric analysis of the literature in this area, this review provides an in-depth analysis of publications related to oxidative stress and pulmonary diseases over four periods, including from 1953 to 2007, 2008 to 2012, 2013 to 2017, and 2018 to 2022. Interest in many pulmonary diseases has increased, and the mechanisms and therapeutic drugs for pulmonary diseases have been well analyzed. Lung injury, lung cancer, asthma, COPD and pneumonia are the 5 most studied pulmonary diseases related to oxidative stress. Inflammation, apoptosis, nuclear factor erythroid 2 like 2 (NRF2), mitochondria, and nuclear factor-κB (NF-κB) are rapidly becoming the most commonly used top keywords. The top thirty medicines most studied for treating different pulmonary diseases were summarized. Antioxidants, especially those targeting reactive oxygen species (ROS) in specific organelles and certain diseases, may be a substantial and necessary choice in combined therapies rather than acting as a single "magic bullet" for the effective treatment of refractory pulmonary diseases.

Vitamin E stabilizes iron and mitochondrial metabolism in pulmonary fibrosis.

Introduction: Pulmonary fibrosis (PF) is a fatal chronic lung disease that causes structural damage and decreased lung function and has a poor prognosis. Currently, there is no medicine that can truly cure PF. Vitamin E (VE) is a group of natural antioxidants with anticancer and antimutagenic properties. There have been a few reports about the attenuation of PF by VE in experimental animals, but the molecular mechanisms are not fully understood. Methods: Bleomycin-induced PF (BLM-PF) mouse model, and cultured mouse primary lung fibroblasts and MLE 12 cells were utilized. Pathological examination of lung sections, immunoblotting, immunofluorescent staining, and real-time PCR were conducted in this study. Results: We confirmed that VE significantly delayed the progression of BLM-PF and increased the survival rates of experimental mice with PF. VE suppressed the pathological activation and fibrotic differentiation of lung fibroblasts and epithelial-mesenchymal transition and alleviated the inflammatory response in BLM-induced fibrotic lungs and pulmonary epithelial cells in vitro. Importantly, VE reduced BLM-induced ferritin expression in fibrotic lungs, whereas VE did not exhibit iron chelation properties in fibroblasts or epithelial cells in vitro. Furthermore, VE protected against mitochondrial dysmorphology and normalized mitochondrial protein expression in BLM-PF lungs. Consistently, VE suppressed apoptosis in BLM-PF lungs and pulmonary epithelial cells in vitro. Discussion: Collectively, VE markedly inhibited BLM-induced PF through a complex mechanism, including improving iron metabolism and mitochondrial structure and function, mitigating inflammation, and decreasing the fibrotic functions of fibroblasts and epithelial cells. Therefore, VE presents a highly potential therapeutic against PF due to its multiple protective effects with few side effects.

Insight into the mitochondrial unfolded protein response and cancer: opportunities and challenges.

The mitochondrial unfolded protein response (UPRmt) is an evolutionarily conserved protective transcriptional response that maintains mitochondrial proteostasis by inducing the expression of mitochondrial chaperones and proteases in response to various stresses. The UPRmt-mediated transcriptional program requires the participation of various upstream signaling pathways and molecules. The factors regulating the UPRmt in Caenorhabditis elegans (C. elegans) and mammals are both similar and different. Cancer cells, as malignant cells with uncontrolled proliferation, are exposed to various challenges from endogenous and exogenous stresses. Therefore, in cancer cells, the UPRmt is hijacked and exploited for the repair of mitochondria and the promotion of tumor growth, invasion and metastasis. In this review, we systematically introduce the inducers of UPRmt, the biological processes in which UPRmt participates, the mechanisms regulating the UPRmt in C. elegans and mammals, cross-tissue signal transduction of the UPRmt and the roles of the UPRmt in promoting cancer initiation and progression. Disrupting proteostasis in cancer cells by targeting UPRmt constitutes a novel anticancer therapeutic strategy.

JNK/Itch Axis Mediates the Lipopolysaccharide-Induced Ubiquitin-Proteasome-Dependent Degradation of Ferritin Light Chain in Murine Macrophage Cells.

Ferritin, which is composed of a heavy chain and a light chain, plays a critical role in maintaining iron homeostasis by sequestering iron. The ferritin light chain (FTL) is responsible for the stability of the ferritin complex. We have previously shown that overexpression of FTL decreases the levels of the labile iron pool (LIP) and reactive oxygen species (ROS) in lipopolysaccharide (LPS)-treated murine macrophage cells. The protein level of FTL was downregulated by LPS within a short treatment period. However, the mechanism underlying the LPS-induced changes in the FTL levels is not known. In the present study, we report that LPS induces the ubiquitin-proteasome-dependent degradation of FTL and that the mechanism of LPS-induced FTL degradation involves the JNK/Itch axis. We found that LPS downregulates the protein and mRNA levels of FTL in a time-dependent manner. The proteasome inhibitor MG-132 significantly reverses the LPS-induced decrease in FTL. Furthermore, we observed that LPS treatment cannot cause ubiquitination of the lysine site (K105 and K144) mutant of FTL. Interestingly, LPS-mediated ubiquitin-dependent degradation of FTL is significantly inhibited by the JNK-specific inhibitor SP600125. Moreover, LPS could upregulate the protein level of E3 ubiquitin ligase Itch, a substrate of JNK kinases. Immunoprecipitation analyses revealed an increase in the association of FTL with Itch, a substrate of JNK kinases, in response to LPS stimulation. SP600125 decreased LPS-induced Itch upregulation. Taken together, these results suggest that LPS stimulation leads to the degradation of FTL through the ubiquitin-proteasome proteolytic pathway, and this FTL degradation is mediated by the JNK/Itch axis in murine macrophage cells.

Decreased TMPRSS2 expression by SARS-CoV-2 predicts the poor prognosis of lung cancer patients through metabolic pathways and immune infiltration.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has rapidly spread around the world and became a global pandemic in 2020. One promising drug target for SARS-CoV-2 is the transmembrane protease serine 2 (TMPRSS2). This study was designed to explore the expression status, prognostic significance and molecular functions of TMPRSS2 in lung cancer. TMPRSS2 expression was investigated using the TIMER, Oncomine, UALCAN, GEO, HPA and TCGA databases. The prognostic value of TMPRSS2 was examined using Cox regression and a nomogram. KEGG, GO and GSEA were performed to investigate the cellular function of TMPRSS2 in lung cancer. The relationship between TMPRSS2 and immune infiltration was determined using the TIMER and CIBERSORT algorithms. TMPRSS2 mRNA and protein expression was significantly reduced in lung cancer. Decreased TMPRSS2 expression and increased DNA methylation of TMPRSS2 were associated with various clinicopathological parameters in patients with lung cancer. Low TMPRSS2 mRNA expression also correlated with poor outcome in lung cancer patients. Moreover, a nomogram was constructed and exhibited good predictive power for the overall survival of lung cancer patients. KEGG and GO analyses and GSEA implied that multiple immune- and metabolism-related pathways were significantly linked with TMPRSS2 expression. Intriguingly, TMPRSS2 expression associated with immune cell infiltration in lung cancer. More importantly, TMPRSS2 expression was markedly decreased in SARS-CoV-infected cells. These findings indicate that TMPRSS2 may be a promising prognostic biomarker and therapeutic target for lung cancer through metabolic pathways and immune cell infiltration.