Protein Deposition Research Articles

HEBE: A novel chimeric chronokine for ameliorating memory deficits in Alzheimer's disease.

Alzheimer's disease (AD) is a prevalent neurodegenerative disorder characterized by amyloid-β and Tau protein depositions, with treatments focusing on single proteins have shown limited success due to the complexity of pathways involved. This study explored the potential of chronokines -proteins that modulate aging-related processes- as an alternative therapeutic approach. Specifically, we focused on a novel pleiotropic chimeric protein named HEBE, combining s-KL, sTREM2 and TIMP2, guided by bioinformatic analyses to ensure the preservation of each protein's conformation, crucial for their functions. In vitro studies confirmed HEBE's stability and enzymatic activities, even suggesting it has different activities compared to the individual chronokines. In vivo experiments on APP/Tau mice revealed improved learning and memory functions with HEBE treatment, along with decreased levels of phosphorylated Tau and minor effects on amyloid-β levels. These findings suggest that HEBE is as a promising therapeutic candidate for ameliorating memory deficits and reducing pTau in an AD mouse model.

Ablation of LRP6 in alpha-smooth muscle actin-expressing cells abrogates lung inflammation and fibrosis upon bleomycin-induced lung injury.

Tissue fibrosis is a progressive pathological process with excessive deposition of extracellular matrix proteins (ECM). Myofibroblasts, identified by alpha-smooth muscle actin (αSMA) expression, play an important role in tissue fibrosis by producing ECM. Here, we found that the Wnt antagonist Dickkopf1 (DKK1) induced gene expressions associated with inflammation and fibrosis in lung fibroblasts. We demonstrated that genetic deletion of LRP6, a receptor for Wnt ligands and DKK1, in αSMA-expressing cells using Acta2-cre Lrp6fl/fl (Lrp6AKO) mice abrogated the bleomycin (BLM)-induced lung inflammation and fibrosis phenotype, suggesting an important role for LRP6 in modulating inflammation and fibrotic processes in the lung. Our results highlight the crucial role of LRP6 in fibroblasts in regulating inflammation and fibrosis upon BLM-induced lung injury.

A xenogenic-free culture medium for cell micro-patterning systems as cell-instructive biomaterials for potential clinical applications

Cell micro-patterning controls cell fate and function and has potential for generating therapeutically usable mesenchymal stromal cell (MSC) populations with precise functions. However, to date, the micro-patterning of human cells in a translational context has been impossible because only ruminant media supplements, e.g. fetal bovine serum (FBS), are established for use with micro-patterns (MPs). Thus, there are currently no good manufacturing practice (GMP)-compliant media available for MPs. This study tested a xenogenic-free human plasma and platelet lysate (hP + PL) medium supplement to determine its compatibility with MPs. Unfiltered hP + PL medium resulted in significant protein deposition, creating a 'carpet-like' layer that rendered MPs ineffective. Filtration (3×/5×) eliminated this effect. Importantly, quantitative comparison using droplet digital PCR revealed that human MSCs in all media types exhibited similar profiles with strong myogenic Calponin 1/Transgelin 2 (TAGLN2) and weaker osteogenic alkaline phosphatase/Runt-related transcription factor 2 marker expression, and much weaker adipogenic (lipoprotein lipase/peroxisome proliferator-activated receptor gamma) and chondrogenic (collagen type II/aggrecan) expression, with profiles being dominated by myogenic markers. Within these similar profiles, an even stronger induction of the myogenic marker TAGLN2 by all hP + PL- compared to FBS-containing media. Overall, this suggested that FBS can be replaced with hP + PL without altering differentiation profiles. However, assessing individual MSC responses to various MP types with defined categories revealed that unfiltered hP + PL medium was unusable. Importantly, FBS- and 3× filtered hP + PL media were comparable in each differentiation category. Summarized, this study recommends 3× filtered hP + PL as a xenogenic-free and potentially GMP-compliant alternative to FBS as a culture medium supplement for micro-patterning cell populations in both basic and translational research that will ensure consistent and reliable MSC micro-patterning for therapeutic use.

Taurochenodeoxycholic Acid Improves Growth, Physiology, Intestinal Microbiota, and Muscle Development in Red Swamp Crayfish (Procambarus clarkii)

Taurochenodeoxycholic acid (TCDCA), one of the bile acids, is thought to be involved in the regulation of muscle nutrient metabolism and gut microbial homeostasis. However, the effect of dietary addition of TCDCA on Procambarus clarkii is unclear. Therefore, in this study, an 8-week feeding experiment was conducted to explore the potential regulatory mechanisms of TCDCA on P. clarkii growth, physiology, muscle quality and gut microbes. The results indicated that dietary addition of TCDCA not only improved growth performance (final weight; weight gain; and specific growth rate) but also increased muscle elasticity and protein content. In addition, dietary TCDCA promotes muscle growth and development by increasing myofiber length, which is consistent with the activation of the expression of genes related to protein utilization (TOR and AKT) and muscle proliferation and differentiation (MyHC, MLC1, MEF2A, MEF2B). Importantly, 16s rRNA sequencing demonstrated that dietary TCDCA had no significant effect on gut microbial composition (alpha diversity) but significantly increased microbial abundance at the genus level. Functional prediction analysis of differential microbes revealed that dietary TCDCA may promote metabolism by altering gut microbes, thereby promoting muscle quality. In conclusion, our study demonstrates that the dietary addition of TCDCA promotes P. clarkii growth and muscle quality and protein deposition by altering gut microbes.

The fibronectin-targeting PEG-FUD imaging probe shows enhanced uptake during fibrogenesis in experimental lung fibrosis

Progressive forms of interstitial lung diseases, including idiopathic pulmonary fibrosis (IPF), are deadly disorders lacking non-invasive biomarkers for assessment of early disease activity, which presents a major obstacle in disease management. Excessive extracellular matrix (ECM) deposition is a hallmark of these disorders, with fibronectin being an abundant ECM glycoprotein that is highly upregulated in early fibrosis and serves as a scaffold for the deposition of other matrix proteins. Due to its role in active fibrosis, we are targeting fibronectin as a biomarker of early lung fibrosis disease activity via the PEGylated fibronectin-binding polypeptide (PEG-FUD). In this work, we demonstrate the binding of PEG-FUD to the fibrotic lung throughout the course of bleomycin-induced murine model of pulmonary fibrosis. We first analyzed the binding of radiolabeled PEG-FUD following direct incubation to precision cut lung slices from mice at different stages of experimental lung fibrosis. Then, we administered fluorescently labeled PEG-FUD subcutaneously to mice over the course of bleomycin-induced pulmonary fibrosis and assessed peptide uptake 24 h later through ex vivo tissue imaging. Using both methods, we found that peptide targeting to the fibrotic lung is increased during the fibrogenic phase of the single dose bleomycin lung fibrosis model (days 7 and 14 post-bleomycin). At these timepoints we found a correlative relationship between peptide uptake and fibrotic burden. These data suggest that PEG-FUD targets fibronectin associated with active fibrogenesis in this model, making it a promising candidate for a clinically translatable molecular imaging probe to non-invasively determine pulmonary fibrosis disease activity, enabling accelerated therapeutic decision-making.

The Role of Air Pollution and Olfactory Dysfunction in Alzheimer's Disease Pathogenesis.

The escalating issue of air pollution contributes to an alarming number of premature fatalities each year, thereby posing a significant threat to global health. The focus of recent research has shifted towards understanding its potential association with neurodegenerative diseases, specifically Alzheimer's disease (AD). AD is recognised for its characteristic deposition of toxic proteins within the brain, leading to a steady deterioration of cognitive capabilities, memory failure, and, ultimately, death. There is burgeoning evidence implying that air pollution may be a contributing factor to this protein build up, thereby intensifying the course of AD. It has been demonstrated that the olfactory system, responsible for smell perception and processing, acts as a potential gateway for airborne pollutants to inflict brain damage. This review aims to elucidate the relationship between air pollution, olfactory deterioration, and AD. Additionally, this review aims to highlight the potential mechanisms through which pollutants might instigate the development of AD and the role of the olfactory system in disease pathogenesis. Moreover, the diverse model systems employed in exploring the correlation, public health policy ramifications, and prospective directions for future research will be discussed.

Role of Copper and Zinc Ions in the Hydrolytic Degradation of Neurodegeneration-Related Peptides.

Spontaneous cleavage reactions normally occur in vivo on amino acid peptide backbones, leading to fragmentation products that can have different physiological roles and toxicity, particularly when the substrate of the hydrolytic processes are neuronal peptides and proteins highly related to neurodegeneration. We report a hydrolytic study performed with the HPLC-MS technique at different temperatures (4 °C and 37 °C) on peptide fragments of different neuronal proteins (amyloid-β, tau, and α-synuclein) in physiological conditions in the presence of Cu2+ and Zn2+ ions, two metal ions found at millimolar concentrations in amyloid plaques. The coordination of these metal ions with these peptides significantly protects their backbones toward hydrolytic degradation, preserving the entire sequences over two weeks in solution, while the free peptides in the same buffer are fully fragmented after the same or even shorter incubation period. Our data show that peptide cleavage is not only ruled by the chemical sensitivity of amino acids, but the peptide conformation changes induced by metal coordination influence hydrolytic reactions. The enhanced stability of neuronal peptides provided by metal coordination can increase local levels of amyloidogenic species capable of seeding fibril growth, resulting in aberrant protein depositions and deficits in neuronal activity.

Patterns of Tau pathology in patients with anti-IgLON5 disease visualized by Florzolotau (18F) PET.

Anti-IgLON5 disease is a rare autoimmune neurological disorder with prominent Tau protein deposits in the brainstem and hypothalamus. The aim of this study was to visualize the in vivo distribution patterns of Tau protein in patients with anti-IgLON5 disease using the second-generation Tau PET tracer, Florzolotau (18F) PET imaging. Patients diagnosed with anti-IgLON5 disease were enrolled consecutively. Age- and sex-matched healthy controls (HCs) were also enrolled. The uptake of Florzolotau (18F) and 18F-FDG was assessed using both visual and semi-quantitative analysis techniques. A total of 10 patients with anti-IgLON5 disease and 40 HCs were included in the study. All ten patients with anti-IgLON5 disease underwent Florzolotau (18F) PET scans, and five of them underwent 18F-FDG PET scans. Twenty HCs underwent Florzolotau (18F) PET scans, and the remaining 20 HCs underwent 18F-FDG PET scans. In patients with anti-IgLON5 disease, significant uptake of Florzolotau (18F) was observed predominantly in the midbrain, pons, cerebellum, caudate, and putamen. This uptake pattern was notably absent in the control group. Moreover, semi-quantitative analysis techniques demonstrated widespread hypometabolism in the cerebral cortex in patients with anti-IgLON5 disease. This study indicates distinct Tau protein deposition patterns in patients with anti-IgLON5 disease, potentially serving as imaging biomarkers.

Tissue fibrosis in cardiorenal syndrome: crosstalk between heart and kidneys.

Cardiorenal syndrome (CRS) is represented as an intricate dysfunctional interplay between the heart and kidneys, marked by cardiorenal inflammation and fibrosis. Unlike other organs, the repair process in cardiorenal injury involves a regenerative phase characterized by proliferation and polyploidization, followed by a subsequent pathogenic phase of fibrosis. In CRS, acute or chronic cardiorenal injury leads to hyperactive inflammation and fibrotic remodeling, associated with injury-mediated immune cell (Macrophages, Monocytes, and T-cells) infiltration and myofibroblast activation. An inflammatory to fibrotic transition corresponds with macrophage transition (M1-M2) associated with increased TGF-β response. Chronic inflammation disrupts hemodynamic pathways, leading to imbalanced oxidative stress and the production of cytokines and growth factors that promote fibrotic stimulation, contributing to pathological cardiorenal remodeling. The inflammatory response paves the pre-fibrotic cardiorenal niche and drives subsequent fibrotic remodeling by activated myofibroblasts. A fibrotic cardiorenal response in CRS is characterized by increased and degradation-resistant deposition of extracellular proteins especially fibrillar Collagen -I, -III, -V, and non-fibrillar Collagen-IV by active myofibroblasts. Recent advances in basic research animal models of CRS have advanced the knowledge of cardiorenal fibrosis. However, a significant need for clinical applications, trials, and evaluation is still needed. Circulating biomarkers like procollagen peptides and TGF-β have clinically been associated with cardiorenal fibrosis diagnosis in CRS. Treatments targeting the fibrotic pathways have also shown efficacy in amelioration of cardiorenal fibrosis in preclinical models. Recent combination therapies targeting multiple fibrotic pathways have been shown to offer promising results. Understanding the heterogenic pathological progression and fibrogenesis could identify novel therapeutic approaches for clinical CRS diagnosis and treatment.

Proteostasis and lysosomal repair deficits in transdifferentiated neurons of Alzheimer's disease.

Aging is the most prominent risk factor for Alzheimer's disease (AD). However, the cellular mechanisms linking neuronal proteostasis decline to the characteristic aberrant protein deposits in AD brains remain elusive. Here, we develop transdifferentiated neurons (tNeurons) from human dermal fibroblasts as a neuronal model that retains aging hallmarks and exhibits AD-linked vulnerabilities. Remarkably, AD tNeurons accumulate proteotoxic deposits, including phospho-Tau and Aβ, resembling those in AD patient and APP mouse brains. Quantitative tNeuron proteomics identify aging and AD-linked deficits in proteostasis and organelle homeostasis, most notably in endosome-lysosomal components. Lysosomal deficits in aged tNeurons, including constitutive lysosomal damage and ESCRT-mediated lysosomal repair defects, are exacerbated in AD tNeurons and linked to inflammatory cytokine secretion and cell death. Supporting lysosomal deficits' centrality in AD, compounds ameliorating lysosomal function reduce Aβ deposits and cytokine secretion. Thus, the tNeuron model system reveals impaired lysosomal homeostasis as an early event of aging and AD.

Indian Childhood Cirrhosis: Report of 2 Cases With Review of Literature and Implication of Metallothionein Immunohistochemical Expression.

Indian childhood cirrhosis is a chronic liver disease in infants and children. Indian childhood cirrhosis is unique to the Indian subcontinent and occurs from 6 months to 5 years of age. We report 2 cases in a period of 5 years, including 1 male and 1 female. Both children were less than 3 years of age. Presenting complaints were jaundice and hepatosplenomegaly. The clinical diagnosis was metabolic liver disease. Histological findings included diffuse hepatocellular ballooning degeneration, prominent Mallory Denk bodies, diffuse pericellular fibrosis, and marked copper/copper-associated protein deposits, along with the absence of steatosis and glycogenated nuclei. Mettalothionein immunohistochemistry was performed in 1 case and showed strong positivity. The first child developed liver failure and died. The second child was started on oral penicillamine therapy and is alive on the most recent follow-up. Whole-exome studies of both patients showed no significant findings. None of the children had exposure to excess dietary copper. Sporadic cases of Indian childhood cirrhosis continue to occur. There should be greater awareness among pediatricians and pathologists of the disease to enable earlier diagnosis. Awareness of metallothionein expression in biopsies of patients with Indian childhood cirrhosis is important to prevent misdiagnosis of Wilson disease.

Alpha-synuclein inhibits the secretion of extracellular vesicles through disruptions in YKT6 lipidation.

Parkinson's disease is characterized by the presence of α-synuclein (α-syn) primarily containing Lewy bodies in neurons. Despite decades of extensive research on α-syn accumulation, its molecular mechanisms have remained largely unexplored. Recent studies by us and others have suggested that extracellular vesicles (EVs), especially exosomes, can mediate the release of α-syn from cells, and inhibiting this pathway could result in increased intracellular α-syn levels. In this study, we have discovered that elevated levels of α-syn themselves lead to reduced α-syn -containing EVs in α-syn inducible H4 cells and induced pluripotent stem cell-derived dopaminergic (DA) neurons from both sexes. Our investigations have revealed that the impairment in EV secretion is not due to their generation but rather a consequence of changes in a soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein, YKT6. Specifically, as α-syn levels increase, membrane-associated YKT6 is reduced. Pharmacological inhibition of farnesylation using FTI has led to decreased EV secretion and subsequent elevated levels of α-syn. In summary, our findings suggest that increased levels of α-syn impair YKT6-mediated EV secretion, establishing a detrimental cycle of intracellular α-syn accumulation in human DA neurons.Significance Statement Neurodegenerative disorders, including Parkinson's disease (PD), are characterized by the pathological accumulation of insoluble proteins, primarily in neurons. Regulating intracellular levels of these proteins is critical. Despite extensive research for decades, the precise mechanism of these protein deposits remains unexplained. In this study, we discovered that extracellular vesicles (EVs) play a pivotal role in regulating alpha-synuclein (a-syn) levels through release from neurons. Furthermore, increased levels of a-syn impede its EV secretion, creating a pathological loop. Elevated levels of a-syn interfere with the localization of YKT6, a SNARE protein, to the vesicle membrane by inhibiting YKT6 palmitoylation. These findings illustrate a novel mechanism of a-syn accumulation in neurons and provide a target to potentially mitigate PD pathology.

The association of high-density lipoprotein cargo proteins with brain volume in older adults in the Atherosclerosis Risk in Communities (ARIC).

High-density lipoprotein (HDL) modulates the blood-brain barrier and cerebrovascular integrity, likely influencing the risk of Alzheimer's disease (AD), neurodegeneration, and cognitive decline. This study aims to identify HDL protein cargo associated with brain amyloid deposition and brain volume in regions vulnerable to AD pathology in older adults. HDL was separated from the plasma of 65 non-demented participants of the Atherosclerosis Risk in Communities (ARIC) study using a fast protein liquid chromatography method. HDL cargo proteins were measured using a label-free, untargeted proteomic method based on mass spectrometry and data-independent acquisition. Linear regression with multiple imputations assessed the associations between each HDL cargo protein (log2-transformed) and brain amyloid deposition or temporal-parietal meta-ROI volume, adjusting for covariates. The mean (SD) age of the participants was 76.3 (5.4) years old, 53.8% (35/65) female, 30.8% (20/65) black, and 28.1% (18/64, 1 missing) APOE4 carriers. We found few HDL cargo proteins associated with brain amyloid deposition and considerably more HDL cargo proteins associated with temporal-parietal meta-ROI volume. Two HDL cargo proteins mostly associated with temporoparietal meta-ROI volume were fibrinogen B (FGB) and plasminogen (PLG). A doubling of FGB in HDL was associated with a greater temporoparietal meta-ROI volume of 1638 mm3 (95% CI [688, 2589]). In comparison, a doubling of PLG in HDL was associated with a lower temporoparietal meta-ROI of 2025 mm3 (95% CI [-3669, -1034]). This study suggests that HDL cargo proteins associated with temporal-parietal meta-ROI volume are involved in complement and coagulation pathways.

Efficient Biochemical Method for Characterizing and Classifying Related Amyloidogenic Peptides.

Amyloidosis is a group of proteinopathies characterized by the systemic or organ-specific deposition of proteins in the form of amyloid fibers. Nearly 40 proteins play a role in these pathologies, and the structures of the associated fibers are beginning to be determined by Cryo-EM. However, the molecular events underlying the process, such as fiber nucleation and elongation, are poorly understood, which impairs developing efficient therapies. In most cases, only a few dozen amino acids of the pathological protein are found in the final structure of the fibers, while amyloid peptides comprising five to 10 amino acids are involved in the fiber nucleation process. The identification and biochemical characterization of these peptides are therefore of major scientific and clinical importance. We demonstrated that in silico approaches are limited due to the peptides' small size and long-distance intra- and intermolecular interactions that occur during nucleation. To address this problem, we developed a novel biochemical method for characterizing and classifying batches of related peptides. Initial work to optimize our approach is based on the reference peptide PHF6 (β1) from Microtubule-Associated Protein Tau (MAPT) as compared to 22 related peptides. Depending on their biochemical properties and using the Garnier-Delamarche plot we propose, we classified these peptides into three groups: aggregative, amyloid, and soluble (neither aggregative nor amyloid). We emphasize that our biochemical classification method is applicable to any family of peptides and could be scaled up for high-throughput analyses.

MTOR signaling regulates multiple metabolic pathways in human lung fibroblasts after TGF-β and in pulmonary fibrosis.

Idiopathic pulmonary fibrosis is a fatal disease characterized by the transforming growth factor (TGF-β)-dependent activation of lung fibroblasts, leading to excessive deposition of collagen proteins and progressive replacement of healthy lungs with scar tissue. We and others have shown that TGF-β-mediated activation of the mechanistic target of rapamycin complex 1 (mTORC1) and downstream upregulation of activating transcription factor 4 (ATF4) promotes metabolic reprogramming in lung fibroblasts characterized by upregulation of the de novo synthesis of glycine, the most abundant amino acid found in collagen protein. Whether mTOR and ATF4 regulate other metabolic pathways in lung fibroblasts has not been explored. Here, we used RNA sequencing to determine how both ATF4 and mTOR regulate gene expression in human lung fibroblasts following TGF-β. We found that ATF4 primarily regulates enzymes and transporters involved in amino acid homeostasis as well as aminoacyl-tRNA synthetases. mTOR inhibition resulted not only in the loss of ATF4 target gene expression but also in the reduced expression of glycolytic enzymes and mitochondrial electron transport chain subunits. Analysis of TGF-β-induced changes in cellular metabolite levels confirmed that ATF4 regulates amino acid homeostasis in lung fibroblasts, whereas mTOR also regulates glycolytic and TCA cycle metabolites. We further analyzed publicly available single-cell RNA-seq datasets and found increased expression of ATF4 and mTOR-regulated genes in pathologic fibroblast populations from the lungs of patients with IPF. Our results provide insight into the mechanisms of metabolic reprogramming in lung fibroblasts and highlight novel ATF4 and mTOR-dependent pathways that may be targeted to inhibit fibrotic processes.NEW & NOTEWORTHY Here, we used transcriptomic and metabolomic approaches to develop a more complete understanding of the role that mTOR, and its downstream effector ATF4, play in promoting metabolic reprogramming in lung fibroblasts. We identify novel metabolic pathways that may promote pathologic phenotypes, and we provide evidence from single-cell RNA-seq datasets that similar metabolic reprogramming occurs in patient lungs.

Assessing plasma-activated water as an acidic and sanitizer solution in clean-in-place (CIP) and comparing efficacy with other traditional CIP chemicals.

Cleaning-in-place (CIP) is the most commonly used cleaning and sanitation procedure for removing fouling deposits. Traditional CIP includes a series of chemical cleaning cycles, including alkaline, acid, and sanitizer. However, these chemicals are hazardous to the environment and employees. Plasma-activated water (PAW), generated by exposing water to plasma (the fourth state of matter), was selected as a CIP cleaning solution due to its acidic pH and antimicrobial properties. The aim of this study was to evaluate the efficacy of PAW as a CIP cleaning solution for dairy (whey)- and plant (pea)-based fouling removal. PAW was used in place of acid in traditional CIP for fouling removal in a continuous system and to test alkaline neutralizing capacity. Later, individual CIP chemicals were used to evaluate their efficacy against mixed-species biofilms. All the treatments were performed in triplicate, and a significant difference was determined using a one-way analysis of variance (ANOVA) at p<0.05. Traditional CIP with acid and CIP with PAW were able to reduce dairy-based protein fouling by 49% and 15%, respectively. However, CIP with acid and PAW removed 100% plant-based protein fouling deposits. Moreover, PAW was able to neutralize more alkaline residues compared to acid in the CIP cycle. The result also showed that PAW alone reduced biofilms on whey and pea protein deposits by 4.2 and 3.0 log CFU/coupon, while traditional CIP sanitizer achieved reduction by 1.8 and 3.2 log CFU/coupon, respectively. PAW, being an eco-friendly solution, can be a viable alternative to sanitizer in traditional CIP. PRACTICAL APPLICATION: Plasma-activated water (PAW) could be a promising eco-friendly alternative solution to traditional cleaning-in-place (CIP) chemicals in the food industry. By effectively removing fouling deposits while also neutralizing alkaline residues, PAW shows promise for industrial applications in dairy- and plant-based food processing facilities. Its ability to remove biofilms from protein deposits suggests potential benefits for maintaining sanitation standards in food production environments, making PAW a viable option for improving cleaning practices while minimizing environmental impact and ensuring employee safety.

Testosterone deficiency aggravates diet-induced non-alcoholic fatty liver disease by inducing hepatocyte ferroptosis via targeting BMAL1 in mice.

Testosterone deficiency is linked to an increased prevalence of non-alcoholic fatty liver disease (NAFLD), although the mechanisms underlying this association are not fully understood. Ferroptosis, a regulated cell death pathway driven by iron-dependent lipid peroxidation, has been suggested to play a role in NAFLD pathogenesis. Since testosterone deficiency is associated with lipid disorders and iron deposition, we hepothesize that ferroptosis may be involved in the pathogenesis of diet-induced NAFLD exacerbated by testosterone deficiency. Apolipoprotein E (APOE-/-) mice were subjected to sham surgery or bilateral castration and subsequently fed a high-fat diet for 16weeks. Liver gene expression was analyzed using RNA sequencing. Additional assessments included blood analysis, histological staining, measurement of iron and antioxidant enzyme levels, quantitative real-time PCR, Western blotting, and electron microscopy. The effects of testosterone on ferroptosis induced by free fatty acids (FFAs) and Erastin were further investigated in HepG2 cells in vitro. Testosterone deficiency resulted in increased hepatic lipid accumulation and macrovesicular steatosis in high-fat diet-fed APOE-/- mice, accompanied by hepatic inflammation, fibrosis, and elevated liver enzyme levels. Transcriptomic analysis revealed that testosterone deficiency affects ferroptosis and circadian rhythm-related signaling pathways. Castrated APOE-/- mice exhibited significantly higher hepatic iron deposition, lipid peroxidation, and expression of key ferroptosis-related proteins, along with decreased Brain and muscle ARNT-like gene 1 (BMAL1) protein expression. In vitro, testosterone treatment reduced lipid and iron accumulation and lipid peroxidation in HepG2 cells subjected to FFAs and Erastin. Moreover, BMAL1 knockdown negated the protective effects of testosterone against ferroptosis in hepatocytes. Our study demonstrated that testosterone deficiency exacerbates NAFLD induced by a high-fat diet by promoting hepatocyte ferroptosis through modulation of the circadian protein BMAL1.

Oxidative/Nitrosative Stress, Apoptosis, and Redox Signaling: Key Players in Neurodegenerative Diseases.

Neurodegenerative diseases are significant health concerns that have a profound impact on the quality and duration of life for millions of individuals. These diseases are characterized by pathological changes in various brain regions, specific genetic mutations associated with the disease, deposits of abnormal proteins, and the degeneration of neurological cells. As neurodegenerative disorders vary in their epidemiological characteristics and vulnerability of neurons, treatment of these diseases is usually aimed at slowing disease progression. The heterogeneity of genetic and environmental factors involved in the process of neurodegeneration makes current treatment methods inadequate. However, the existence of common molecular mechanisms in the pathogenesis of these diseases may allow the development of new targeted therapeutic strategies. Oxidative and nitrosative stress damages membrane components by accumulating ROS and RNS and disrupting redox balance. This process results in the induction of apoptosis, which is important in the pathogenesis of neurodegenerative diseases through oxidative stress. Studies conducted using postmortem human samples, animal models, and cell cultures have demonstrated that oxidative stress, nitrosative stress, and apoptosis are crucial factors in the development of diseases such as Alzheimer's, Parkinson's, Multiple Sclerosis, amyotrophic lateral sclerosis, and Huntington's disease. The excessive production of reactive oxygen and nitrogen species, elevated levels of free radicals, heightened mitochondrial stress, disturbances in energy metabolism, and the oxidation and nitrosylation of cellular macromolecules are recognized as triggers for neuronal cell death. Challenges in managing and treating neurodegenerative diseases require a better understanding of this field at the molecular level. Therefore, this review elaborates on the molecular mechanisms by which oxidative and nitrosative stress are involved in neuronal apoptosis.

TDP-43 transports ferritin heavy chain mRNA to regulate oxidative stress in neuronal axons.

Amyotrophic lateral sclerosis (ALS) is characterized by the mislocalization and abnormal deposition of TAR DNA-binding protein 43 (TDP-43). This protein plays important roles in RNA metabolism and transport in motor neurons and glial cells. In addition, abnormal iron accumulation and oxidative stress are observed in the brain and spinal cord of patients with ALS exhibiting TDP-43 pathology and in animal models of ALS. We have previously demonstrated that TDP-43 downregulation significantly affects the expression of ferritin heavy chain (Fth1) mRNA in the axonal regions of neurons. Nevertheless, the mechanisms by which TDP-43 contributes to oxidative stress and iron accumulation in the central nervous system remain elusive. In this study, we aimed to investigate whether Fth1 mRNA is a target transported to the axon by TDP-43 using biophysical and biochemical analyses. Our results revealed Fth1 mRNA as a target mRNA transported to axons by TDP-43. Moreover, we demonstrated that TDP-43 regulates iron homeostasis and oxidative stress in neurons via Fth1 mRNA transport to the axons, possibly followed by a local translation of the ferritin heavy chain in the axons. This study suggests that TDP-43 plays an important role in preventing iron-mediated oxidative stress in neurons, with its loss contributing to ALS pathogenesis.

Salvianolic acid C promotes renal gluconeogenesis in fibrotic kidneys through PGC1α.

Impaired renal gluconeogenesis is recently identified as a hallmark of chronic kidney disease. However, the therapeutic approach to promote renal gluconeogenesis in CKD is still lacking. We aimed to study whether Salvianolic acid C (SAC), a nature compound extracted from the traditional Chinese medicine Danshen, inhibits renal fibrosis through promotion of gluconeogenesis. TGF-β stimulated HK2 human renal epithelial cells and mice with unilateral ureteral obstruction (UUO) were used as in vitro and in vivo models to study renal fibrosis. Fibrotic and gluconeogenic changes were determined by Western blotting analysis, quantitative PCR and Masson staining. Glucose and lactate concentrations were measured in cell culture and renal tissues. We found that SAC treatment inhibits the deposition of extracellular matrix proteins and the expression of fibrotic markers such as fibronectin, N-cadherin, Vimentin, aSMA, pSmad3, and Snail in UUO kidneys or renal cells. Inhibition of these fibrotic markers by SAC treatment was associated with enhanced expression of three gluconeogenic enzymes such as PCK1, G6PC and FBP1 in renal tissues or cells. SAC increase the concentration of glucose in the supernatant of renal cells. Lactate concentration was reduced by SAC in renal tissues or cells. Pyruvate and glucose tolerance tests showed that SAC improve the impaired glucose metabolism systemically in UUO mice. Peroxisome proliferator activated receptor gamma coactivator 1 alpha (PGC1ɑ) was downregulated in mouse kidneys after UUO operation, which was increased by SAC treatment. Moreover, PGC1α inhibitor SR-18292 reversed the anti-fibrotic effect and pro-gluconeogenic effect caused by SAC in renal cells. In conclusion, SAC inhibits renal fibrosis through promotion of PGC1α-mediated renal gluconeogenesis.