Taurine protects against As2O3-induced autophagy in livers of rat offsprings through PPARγ pathway

Proteomic analysis of the effects of Dictyophora polysaccharide on arsenic-induced hepatotoxicity in rats

Arsenic (As) is a highly toxic environmental toxicant and a known human carcinogen. Long-term exposure to As can cause liver injury. Dictyophora polysaccharide (DIP) is a biologically active natural compound found in the Dictyophora with excellent antioxidation, anti-inflammation, and immune protection properties. In this study, the Sprague-Dawley (SD) rat model of As toxicity was established using a feeding method, followed by DIP treatment in rats with As-induced liver injury. The molecular mechanisms of As toxicity to the rat liver and the protective effect of DIP were investigated by proteomic studies. The results showed that 172, 328 and 191 differentially expressed proteins (DEPs) were identified between the As-exposed rats versus control rats (As/Ctrl), DIP treated rats versus As-exposed rats (DIP+As/As), and DIP treated rats versus control rats (DIP+As /Ctrl), respectively. Among them, the expression of 90 DEPs in the As/Ctrl groups was reversed by DIP treatment. As exposure caused dysregulation of metabolic pathways, mitochondria, oxidative stress, and apoptosis-related proteins in the rat liver. However, DIP treatment changed or restored the levels of these proteins, which attenuated the damage to the livers of rats caused by As exposure. The results provide new insights into the mechanisms of liver injury induced by As exposure and the treatment of DIP in As poisoning.

The Protective Effects of Taurine, a Non-essential Amino Acid, Against Metals Toxicities: A Review Article

Taurine is a non-proteinogenic amino acid derived from cysteine. It is involved in several phenomena such as the regulation of growth and differentiation, osmoregulation, neurohormonal modulation, and lipid metabolism. Taurine is important because of its high levels in several tissues such as the central nervous system (CNS), heart, skeletal muscles, retinal membranes, and platelets. In this report, we present the functional properties of taurine indicating that it has potential effects on various metal toxicities. Therefore, a comprehensive literature review was performed using the Scopus, PubMed, and Web of Science databases. According to the search keywords, 61 articles were included in the study. The results indicate that taurine protects tissues against metal toxicity through enhancement of enzymatic and non-enzymatic antioxidant capacity, modulation of oxidative stress, anti-inflammatory and anti-apoptotic effects, involvement in different molecular pathways, and interference with the activity of various enzymes. Taken together, taurine is a natural supplement that presents antitoxic effects against many types of compounds, especially metals, suggesting public consumption of this amino acid as a prophylactic agent against the incidence of metal toxicity.

The Potential Role of PPARs in the Fetal Origins of Adult Disease

The fetal origins of adult disease (FOAD) hypothesis holds that events during early development have a profound impact on one’s risk for the development of future adult disease. Studies from humans and animals have demonstrated that many diseases can begin in childhood and are caused by a variety of early life traumas, including maternal malnutrition, maternal disease conditions, lifestyle changes, exposure to toxins/chemicals, improper medication during pregnancy, and so on. Recently, the roles of Peroxisome proliferator-activated receptors (PPARs) in FOAD have been increasingly appreciated due to their wide variety of biological actions. PPARs are members of the nuclear hormone receptor subfamily, consisting of three distinct subtypes: PPARα, β/δ, and γ, highly expressed in the reproductive tissues. By controlling the maturation of the oocyte, ovulation, implantation of the embryo, development of the placenta, and male fertility, the PPARs play a crucial role in the transition from embryo to fetus in developing mammals. Exposure to adverse events in early life exerts a profound influence on the methylation pattern of PPARs in offspring organs, which can affect development and health throughout the life course, and even across generations. In this review, we summarize the latest research on PPARs in the area of FOAD, highlight the important role of PPARs in FOAD, and provide a potential strategy for early prevention of FOAD.

Anti-proliferation and apoptosis-inducing effects of dihydroartemisinin on SH-SY5Y cells and metabolomic analysis

BACKGROUND

In childhood, metastatic neuroblastoma (NB) is the most common extracranial solid tumor, but there are no appropriate drugs for its treatment. Dihydroartemisinin (DHA), a drug for malaria treatment, has therapeutic potential in several cancers; however, its mechanisms remain unclear. This study aimed to investigate the anti-proliferation effect of DHA on SH-SY5Y cells and to explore its mechanism in vitro.

METHODS

We used 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay to measure the half-maximal inhibitory concentration (IC50) of DHA; western blot was used to determine protein levels; propidium iodide (PI) staining was used to determine apoptotic cells; JC-1 staining to measure mitochondrial membrane potential; and dichloro-dihydro-fluorescein diacetate (DCFH-DA) staining was used to determine reactive oxygen species (ROS). Metabonomic analysis was performed by using ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS)-based untargeted metabolomics. Multivariate statistical analysis was performed to screen potential metabolites associated with DHA treatment in SH-SY5Y cells.

RESULTS

It was shown that DHA inhibited SH-SY5Y cell proliferation and increased poly (ADP-ribose) polymerase (PARP-1) and caspase 3 in a dose-dependent manner. In Further, DHA promoted ROS generation and γH2AX expression. In addition, a total of 125 proposed metabolites in SH-SY5Y cells and 45 vital metabolic pathways were identified through UHPLC-MS/MS-based untargeted metabolomic analysis.

CONCLUSIONS

These data suggest that DHA could regulate taurine, linoleic acid, phenylalanine metabolism, and tryptophan metabolism, which are involved in the anti-proliferation effect of DHA in SH-SY5Y cells.

Exosomes derived from bone mesenchymal stem cells attenuate myocardial fibrosis both in vivo and in vitro via autophagy activation: the key role of miR-199a-3p/mTOR pathway

Autophagy suppression plays key a role during myocardial fibrosis (MF) progression. Exosomes from stem cells attenuate MF. The current study aimed to explain the antifibrosis effects of exosomes by focusing on microRNAs (miRs). MF was induced in rats using transverse aortic constriction (TAC) method and handled with exosomes from bone mesenchymal stem cells (BMSCs). The results of in vivo assays were verified with H9c2 cells. MiR expression profile was determined using microarray detection. The influence of miR-199a-3p modulation in vivo and in vitro on the antifibrosis effect of exosomes then was assessed. Exosomes attenuated MF by inhibiting inflammation, improving tissue structure, and inhibiting fibrosis-related indicators in TAC rats, and the effects were associated with autophagy activation. In H9c2 cells, exosomes suppressed cell viability, induced cell apoptosis, inhibited fibrosis-related indicators, while and the inhibition of autophagy by 3-MA would block the effect of exosomes. Based on the microarray detection, miR-199a-3p level was selected as therapeutic target. The inhibition of miR-199a-3p impaired the antifibrosis effects of exosomes on H9c2 cells, which was associated with autophagy inhibition. Collectively, exosomes from BMSCs exerted antifibrosis effects via the distant transfer of miR-199a-3p to heart tissues, which induced autophagy by inhibiting mTOR.

Transcriptional Regulation of Hepatic Autophagy by Nuclear Receptors

Autophagy is an adaptive self-eating process involved in degradation of various cellular components such as carbohydrates, lipids, proteins, and organelles. Its activity plays an essential role in tissue homeostasis and systemic metabolism in response to diverse challenges, including nutrient depletion, pathogen invasion, and accumulations of toxic materials. Therefore, autophagy dysfunctions are intimately associated with many human diseases such as cancer, neurodegeneration, obesity, diabetes, infection, and aging. Although its acute post-translational regulation is well described, recent studies have also shown that autophagy can be controlled at the transcriptional and post-transcriptional levels. Nuclear receptors (NRs) are in general ligand-dependent transcription factors consisting of 48 members in humans. These receptors extensively control transcription of a variety of genes involved in development, metabolism, and inflammation. In this review, we discuss the roles and mechanisms of NRs in an aspect of transcriptional regulation of hepatic autophagy, and how the NR-driven autophagy pathway can be harnessed to treat various liver diseases.

Long-Term Dietary Taurine Lowers Plasma Levels of Cholesterol and Bile Acids

Cholesterol is an essential lipid in vertebrates, but excess blood cholesterol promotes atherosclerosis. In the liver, cholesterol is metabolized to bile acids by cytochrome P450, family 7, subfamily a, polypeptide 1 (CYP7A1), the transcription of which is negatively regulated by the ERK pathway. Fibroblast growth factor 21 (FGF21), a hepatokine, induces ERK phosphorylation and suppresses Cyp7a1 transcription. Taurine, a sulfur-containing amino acid, reportedly promotes cholesterol metabolism and lowers blood and hepatic cholesterol levels. However, the influence of long-term feeding of taurine on cholesterol levels and metabolism remains unclear. Here, to evaluate the more chronic effects of taurine on cholesterol levels, we analyzed mice fed a taurine-rich diet for 14-16 weeks. Long-term feeding of taurine lowered plasma cholesterol and bile acids without significantly changing other metabolic parameters, but hardly affected these levels in the liver. Moreover, taurine upregulated Cyp7a1 levels, while downregulated phosphorylated ERK and Fgf21 levels in the liver. Likewise, taurine-treated Hepa1-6 cells, a mouse hepatocyte line, exhibited downregulated Fgf21 levels and upregulated promoter activity of Cyp7a1. These results indicate that taurine promotes cholesterol metabolism by suppressing the FGF21/ERK pathway followed by upregulating Cyp7a1 expression. Collectively, this study shows that long-term feeding of taurine lowers both plasma cholesterol and bile acids, reinforcing that taurine effectively prevents hypercholesterolemia.

NLRP3 inflammasome blocked the glycolytic pathway via targeting to PKLR in arsenic-induced hepatic insulin resistance

Arsenic exposure is related to insulin resistance (IR). However, the underlying mechanism is still uncertain. NOD-like receptors containing pyrin domain 3 (NLRP3) inflammasome is a key driving factor of IR. We found that NaAsO₂ caused hepatic IR, activated NLRP3 inflammasome, and inhibited glycolysis pathway in vivo. We also found that tricarboxylic acid cycle (TCA cycle) was inhibited, and the content of hepatic lactate was upregulated with the treatment of arsenic. Consistent with these findings, we found that NLRP3 inflammasome and glycolysis were involved in the development of IR in L-02 cells. Besides, inhibiting NLRP3 inflammasome upregulated aerobic glycolysis and inhibited anaerobic glycolysis. Moreover, we demonstrated that NLRP3 inflammasome could bind to pyruvate kinase, liver and RBC (PKLR). Simultaneously, insulin signaling rather than NLRP3 inflammasome activation was altered by overexpressing PKLR. In summary, after treatment with NaAsO₂, NLRP3 inflammasome blocked the glycolytic pathway via binding to PKLR, which in turn caused hepatic IR_. This study shed new light on the molecular mechanism underlying arsenic-induced IR.

Protective role of taurine against oxidative stress (Review)

Taurine is a fundamental mediator of homeostasis that exerts multiple roles to confer protection against oxidant stress. The development of hypertension, muscle/neuro‑​associated disorders, hepatic cirrhosis, cardiac dysfunction and ischemia/reperfusion are examples of some injuries that are linked with oxidative stress. The present review gives a comprehensive description of all the underlying mechanisms of taurine, with the aim to explain its anti‑oxidant actions. Taurine is regarded as a cytoprotective molecule due to its ability to sustain normal electron transport chain, maintain glutathione stores, upregulate anti‑oxidant responses, increase membrane stability, eliminate inflammation and prevent calcium accumulation. In parallel, the synergistic effect of taurine with other potential therapeutic modalities in multiple disorders are highlighted. Apart from the results derived from research findings, the current review bridges the gap between bench and bedside, providing mechanistic insights into the biological activity of taurine that supports its potential therapeutic efficacy in clinic. In the future, further clinical studies are required to support the ameliorative effect of taurine against oxidative stress.

Ameliorative effect of taurine against diabetes and renal-associated disorders (Review)

To develop novel therapeutic methods for both diabetic and renal disorders, scientists had initially focused on elucidating the molecular mechanisms of taurine in established cell lines and mouse models. Although a large amount of data have been revealed, taurine has been confirmed to be the next step of novel promising therapeutic interventions against diabetic disorders. Taurine appears to ameliorate diabetes 1-related complications in various organs through its antioxidant, anti-inflammatory and anti-hormonal actions. In type 2 diabetes, taurine has been positively implicated in glucose homeostasis, exerting potent hypoglycemic, anti-obesity, hypotensive and hypolipidemic effects. Of particular interest is that taurine provides protection against renal dysfunction, including hypertension and proteinuria, specific glomerular and tubular disorders, acute and chronic renal conditions, and diabetic nephropathy. The ameliorative effects of taurine against renal disorders are based on its osmoregulatory properties, its association with signaling pathways and its association with the renin-angiotensin-aldosterone system (RAAS). Further clinical studies are required to ensure the importance of research findings.

The molecular targets of taurine confer anti-hyperlipidemic effects

Hyperlipidemia, an independent risk factor for atherosclerosis, is regarded as a lipid metabolism disorder associated with elevated plasma triglyceride and/or cholesterol. Genetic factors and unhealthy lifestyles, such as excess caloric intake and physical inactivity, can result in hyperlipidemia. Taurine, a sulfur-containing non-essential amino acid, is abundant in marine foods and has been associated with wide-ranging beneficial physiological effects, with special reference to regulating aberrant lipid metabolism. Its anti-hyperlipidemic mechanism is complex, which is related to many enzymes in the process of fat anabolism and catabolism (e.g., HMGCR, CYP7A1, LDLR, FXR, FAS and ACC). Anti-inflammatory and antioxidant molecular targets, lipid autophagy, metabolic reprogramming and gut microbiota will also be reviewed.

Taurine Alleviates Streptococcus uberis-Induced Inflammation by Activating Autophagy in Mammary Epithelial Cells

Streptococcus uberis infection can cause serious inflammation and damage to mammary epithelial cells and tissues that can be significantly alleviated by taurine. Autophagy plays an important role in regulating immunity and clearing invasive pathogens and may be regulated by taurine. However, the relationships between taurine, autophagy, and S. uberis infection remain unclear. Herein, we demonstrate that taurine augments PTEN activity and inhibits Akt/mTOR signaling, which decreases phosphorylation of ULK1 and ATG13 by mTOR and activates autophagy. Activating autophagy accelerates the degradation of intracellular S. uberis, reduces intracellular bacterial load, inhibits over-activation of the NF-κB pathway, and alleviates the inflammation and damage caused by S. uberis infection. This study increases our understanding of the mechanism through which taurine regulates autophagy and is the first to demonstrate the role of autophagy in S. uberis infected MAC-T cells. Our study also provides a theoretical basis for employing nutritional elements (taurine) to regulate innate immunity and control S. uberis infection. It also provides theoretical support for the development of prophylactic strategies for this important pathogen.

Arsenic induces hepatic insulin resistance via mtROS-NLRP3 inflammasome pathway

Hepatic insulin resistance (IR) is the key event for arsenic-caused type 2 diabetes (T2D). However, the unequivocal mechanism of arsenic-induced hepatic IR remains unclear. The current study determined the role of NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome activation in arsenic-induced IR and revealed the underlying mechanism. Three-month NaAsO₂ gavage led to glucose intolerance and insulin insensitivity, impaired hepatic insulin signaling. Additionally, NaAsO₂ upregulated the level of oxidized mitochondrial DNA (ox-mtDNA) and mitophagy, thereby activating the NLRP3 inflammasome in SD rat liver. In vitro, we demonstrated that NaAsO₂-induced IR depended upon the NLRP3 inflammasome activation. Moreover, inhibiting mitophagy mitigated the NLRP3 inflammasome activation and impaired insulin signaling induced by NaAsO₂. Furthermore, mitochondrial reactive oxygen species (mtROS) scavenger alleviated the upregulated ox-mtDNA and mitophagy, thereby inhibiting the NLRP3 inflammasome activation, and improving insulin signaling. Taken together, these data demonstrated that mtROS-triggered ox-mtDNA, mitophagy, and the activation of NLRP3 inflammasome was involved in arsenic-induced hepatic IR.

Taurine suppresses ROS-dependent autophagy via activating Akt/mTOR signaling pathway in calcium oxalate crystals-induced renal tubular epithelial cell injury

Oxidative stress and autophagy are the key promoters of calcium oxalate (CaOx) nephrolithiasis. Taurine is an antioxidant that plays a protective role in the pathogenesis of kidney disease. Previous studies found that taurine suppressed cellular oxidative stress, and inhibited autophagy activation. However, the effect of taurine on CaOx kidney stone formation remains unknown. In the present work, we explored the regulatory effects of taurine on CaOx crystals-induced HK-2 cell injury. Results showed that pretreatment with taurine significantly enhanced the viability of HK-2 cells and ameliorated kidney tissue injury induced by CaOx crystals. Taurine also markedly reduced the levels of inflammatory cytokines, apoptosis, and CaOx crystals deposition. Furthermore, we observed that taurine supplementation alleviated CaOx crystals-induced autophagy. Mechanism studies showed that taurine reduced oxidative stress via increasing SOD activity, reducing MDA concentration, alleviating mitochondrial oxidative injury, and decreasing the production of intracellular ROS. Taurine treatment also effectively activated Akt/mTOR signaling pathway in CaOx crystals-induced HK-2 cells both in vitro and in vivo. In summary, the current study shows that taurine inhibits ROS-dependent autophagy via activating Akt/mTOR signaling pathway in CaOx crystals-induced HK-2 cell and kidney injury, suggesting that taurine may serve as an effective therapeutic agent for the treatment of CaOx nephrolithiasis.

IRE1α/NOX4 signaling pathway mediates ROS-dependent activation of hepatic stellate cells in NaAsO2 -induced liver fibrosis

Liver fibrosis is a severe health problem worldwide, and it is characterized by the activation of hepatic stellate cells (HSCs) and excessive deposition of collagen. Prolonged arsenic exposure can induce HSCs activation and liver fibrosis. In the present study, the results showed that chronic NaAsO₂ ingestion could result in liver fibrosis and oxidative stress in Sprague-Dawley rats, along with representative collagen deposition and HSCs activation. In addition, the inositol-requiring enzyme 1α (IRE1α)-endoplasmic reticulum (ER)-stress pathway was activated, and the activity of nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4) was upregulated in rat livers. Simultaneously, the excessive production of reactive oxygen species (ROS) could induce HSCs activation, and NOX4 played an important role in generating ROS in vitro. Moreover, ER stress occurred with HSCs activation at the same time under NaAsO₂ exposure, and during ER stress, the IRE1α pathway was responsible for NOX4 activation. Therefore, inhibition of IRE1α activation could attenuate the HSCs activation induced by NaAsO₂ . In conclusion, the present study manifested that inorganic arsenic exposure could activate HSCs through IRE1α/NOX4-mediated ROS generation.

The Role of Autophagy and NLRP3 Inflammasome in Liver Fibrosis

Liver fibrosis is an intrinsic repair process of chronic injury with excessive deposition of extracellular matrix. As an early stage of various liver diseases, liver fibrosis is a reversible pathological process. Therefore, if not being controlled in time, liver fibrosis will evolve into cirrhosis, liver failure, and liver cancer. It has been demonstrated that hepatic stellate cells (HSCs) play a crucial role in the formation of liver fibrosis. In particular, the activation of HSCs is a key step for liver fibrosis. Recent researches have suggested that autophagy and inflammasome have biological effect on HSC activation. Herein, we review current studies about the impact of autophagy and NOD-like receptors containing pyrin domain 3 (NLRP3) inflammasome on liver fibrosis and the underlying mechanisms.

Taurine attenuates liver autophagy and injury of offspring in gestational diabetic mellitus rats

PURPOSE

Gestational diabetes mellitus (GDM) has many adverse effects on offspring, such as abnormal glycolipid metabolism, obesity, insulin resistance, mental retardation, schizophrenia and so on.

METHODS

We established a GDM rat model by injecting 1% streptozotocin associated with a high-fat diet one week before pregnancy, and offspring rats were sacrificed at 8 weeks of age to obtain liver tissue for study. We used hematoxylin-eosin (HE) staining to observe liver morphological changes, Tunel staining for hepatocyte apoptosis, transmission electron microscope for liver ultrastructure, and western blot for protein expression in liver tissue.

RESULTS

Compared with normal offspring rats, hepatocytes of GDM offspring rats showed obvious edema, liver organ index increased, and hepatocyte apoptosis and autophagosome in the liver were significantly increased; Bax, cleaved-caspase3/caspase3, LCII, Beclin 1, P-IKBα/IKBα and P-p65/p6 protein expression in the liver were significantly increased; Bcl2, p62 and PPARγ protein expression in the liver were significantly decreased. Tau prevented the GDM-related effects in the offspring: Tau decreased hepatocyte edema (or even disappears), liver organ index, hepatocyte apoptosis and the number of autophagosomes in the liver. In addition, Tau also decreased Bax, cleaved-caspase3/caspase3, LCII, Beclin 1, P-IKBα/IKBα and P-p65/p6 protein expression, and increased Bcl2, p62 and PPARγ protein expression in the liver of GDM offspring rats.

CONCLUSION

Taurine should be considered as a potential gestational nutritional supplement to prevent liver damage in GDM offspring.

Intracerebral Hemorrhage Induced Brain Injury Is Mediated by the Interleukin-12 Receptor in Rats

BACKGROUND

IL-12 inhibition of the endothelial cell functions and angiogenesis is mediated by the cross-talk between the lymphocyte and the endothelial cells, which plays a key role in inhibiting the process of angiogenesis in the eyeballs and in malignant tumors.

METHODS

We established the intracerebral hemorrhage (ICH) rat model, and IL-12 receptor beta monoclonal antibody was injected into the ICH rats. Western blot, immunofluorescence and RT-qPCR were used to detect the gene expression. Brain water content, EB staining, Garcia test, Beam walking test and wire hanging test were used to assess the injury of brain in ICH rats.

RESULTS

IL-12 gene was significantly increase in hematoma border tissue of ICH rats, and IL-12 protein mainly localized in monocytes. Anti-IL-12 treatment with IL-12 monoclonal antibodies could not only significantly decrease the brain water content and EB content in brain tissues of ICH rats, but also significantly increase the score of the Garcia, Beam balance and the Wire hanging test in ICH rats. Moreover, anti-IL-12 treatment significantly decrease the expression of pro-inflammatory gene, inflammatory gene, p-JAK2/JAK2 and p-STAT4/STAT4 protein, but significantly increase the expression anti-inflammatory gene and CD31 protein, and M2 macrophage ratio in hematoma border tissues of ICH rats. In vitro, rmIL-12 inhibited the tube formation of brain microvascular endothelial cells (BMVES) in BMVES and bone marrow-derived monocytes (BMDM) co-culture systems, but not work in a separately cultured BMVES system. In addition, Fedratinib not only reduced p-JAK2/JAK2 and p-STAT4/STAT4 protein expression in BMDM after treating with b-FGF and rmIL-12, but also significantly increased the tube formation of BMVES in BMVES and BMDM co-culture systems after treating with b-FGF and rmIL-12.

CONCLUSION

Blockade of IL-12 receptor attenuated brain injury after ICH in rat by promoting angiogenesis, and the mechanism might be related to blocking IL-12 could inhibit M2 cell activation via the JAK2/STAT4 pathway.

Chorea-related mutations in PDE10A result in aberrant compartmentalization and functionality of the enzyme

Phosphodiesterase 10A (PDE10A) is as a target of interest in Huntington’s disease (HD) as levels of the enzyme have been shown to decrease prior to the development of the hallmark motor symptoms. Clearly, a better understanding of how PDE10A protein levels change as HD develops is required. Here we show that mutations in the regulatory GAF domains of PDE10A that cause hyperkinetic syndromes in humans lead to misprocessing of the PDE10A enzyme that ultimately leads to targeted degradation by the ubiquitin proteasome system or clearance by autophagy. Both mechanisms result in a paucity of PDE10A activity that lead to a loss of movement coordination. Our research suggests that similar mechanisms may underpin PDE10A loss during HD.

A robust body of evidence supports the concept that phosphodiesterase 10A (PDE10A) activity in the basal ganglia orchestrates the control of coordinated movement in human subjects. Although human mutations in the PDE10A gene manifest in hyperkinetic movement disorders that phenocopy many features of early Huntington’s disease, characterization of the maladapted molecular mechanisms and aberrant signaling processes that underpin these conditions remains scarce. Recessive mutations in the GAF-A domain have been shown to impair PDE10A function due to the loss of striatal PDE10A protein levels, but here we show that this paucity is caused by irregular intracellular trafficking and increased PDE10A degradation in the cytosolic compartment. In contrast to GAF-A mutants, dominant mutations in the GAF-B domain of PDE10A induce PDE10A misfolding, a common pathological phenotype in many neurodegenerative diseases. These data demonstrate that the function of striatal PDE10A is compromised in disorders where disease-associated mutations trigger a reduction in the fidelity of PDE compartmentalization.

Zearalenone induces NLRP3-dependent pyroptosis via activation of NF-κB modulated by autophagy in INS-1 cells

Zearalenone (ZEA), one of the mycotoxins widely found in food and feed, can stimulate an inflammatory reaction. In the present study, we demonstrated that ZEA induced the activation of NLRP3 inflammasome even pyroptotic cell death in rat Insulinoma Cell Line (INS-1). Meanwhile, according to the results of western blot and TEM, the level of autophagy was elevated by ZEA, which protected against the activation of NLRP3 inflammasome and inflammatory response caused by ZEA. Furthermore, we indicated that ZEA-induced NF-κB p65 activation contributed to the activation of the NLRP3 inflammasome, inflammatory response, and pyroptosis in INS-1 cells, which were indicated by western blot and immunofluorescence, and the activation of NF-κB p65 induced by ZEA was autophagy-dependent. This study demonstrates that ZEA induces NLRP3-dependent pyroptosis via activation of NF-κB modulated by autophagy in INS-1 cells.

Gestational Arsenic Trioxide Exposure Acts as a Developing Neuroendocrine-Disruptor by Downregulating Nrf2/PPARγ and Upregulating Caspase-3/NF-ĸB/Cox2/BAX/iNOS/ROS

The goal of this investigation was to evaluate the effects of gestational administrations of arsenic trioxide (ATO; As₂O₃) on fetal neuroendocrine development (the thyroid-cerebrum axis). Pregnant Wistar rats were orally administered ATO (5 or 10 mg/kg) from gestation day (GD) 1 to 20. Both doses of ATO diminished free thyroxine and free triiodothyronine levels and augmented thyrotropin level in both dams and fetuses at GD 20. Also, the maternofetal hypothyroidism in both groups caused a dose-dependent reduction in the fetal serum growth hormone, insulin growth factor-I (IGF-I), and IGF-II levels at embryonic day (ED) 20. These disorders perturbed the maternofetal body weight, fetal brain weight, and survival of pregnant and their fetuses. In addition, destructive degeneration, vacuolation, hyperplasia, and edema were observed in the fetal thyroid and cerebrum of both ATO groups at ED 20. These disruptions appear to depend on intensification in the values of lipid peroxidation, nitric oxide, and H₂O₂, suppression of messenger RNA (mRNA) expression of nuclear factor erythroid 2-related factor 2 and peroxisome proliferator-activated receptor gamma, and activation of mRNA expression of caspase-3, nuclear factor kappa-light-chain-enhancer of activated B cells, cyclooxygenase-2, Bcl-2–associated X protein, and inducible nitric oxide synthase in the fetal cerebrum. These data suggest that gestational ATO may disturb thyroid-cerebrum axis generating fetal neurodevelopmental toxicity.

Taurine and its analogs in neurological disorders: Focus on therapeutic potential and molecular mechanisms

Taurine is a sulfur-containing amino acid and known as semi-essential in mammals and is produced chiefly by the liver and kidney. It presents in different organs, including retina, brain, heart and placenta and demonstrates extensive physiological activities within the body. In the several disease models, it attenuates inflammation- and oxidative stress-mediated injuries. Taurine also modulates ER stress, Ca2+ homeostasis and neuronal activity at the molecular level as part of its broader roles. Different cellular processes such as energy metabolism, gene expression, osmosis and quality control of protein are regulated by taurine. In addition, taurine displays potential ameliorating effects against different neurological disorders such as neurodegenerative diseases, stroke, epilepsy and diabetic neuropathy and protects against injuries and toxicities of the nervous system. Several findings demonstrate its therapeutic role against neurodevelopmental disorders, including Angelman syndrome, Fragile X syndrome, sleep-wake disorders, neural tube defects and attention-deficit hyperactivity disorder. Considering current biopharmaceutical limitations, developing novel delivery approaches and new derivatives and precursors of taurine may be an attractive option for treating neurological disorders. Herein, we present an overview on the therapeutic potential of taurine against neurological disorders and highlight clinical studies and its molecular mechanistic roles. This article also addresses the neuropharmacological potential of taurine analogs.

Taurine protected As2O3-induced the activation of hepatic stellate cells through inhibiting PPARα-autophagy pathway

The activation of hepatic stellate cells (HSCs) is a key event in the development of hepatic fibrosis caused by arsenic. However, it is unclear how arsenic induces the activation of HSCs. In the present study, we found that arsenic trioxide (As₂O₃) induced liver tissue damage, stimulated autophagy and HSCs activation, and increased collagen accumulation in the liver of mice. Supplemented with taurine (Tau) attenuated the changes mentioned above caused by As₂O₃. In human hepatic stellate cell line LX-2 cells, we found that As₂O₃-induced activation of HSCs was autophagy-dependent, and we found that peroxisome proliferator activated receptors alpha (PPARα) played an important role in arsenic-induced HSCs activation. In addition, inhibiting autophagy and PPARα alleviated the activation of HSCs and lipid droplet loss induced by As₂O₃. Moreover, we found that Tau alleviated As₂O₃-induced elevation of autophagy and PPARα expression, and activation of the HSCs. Our results indicated that autophagy was regulated by PPARα and was involved in lipid droplet loss during the activation of HSCs. Tau alleviated As₂O₃-induced HSCs activation by inhibiting the PPARα/autophagy pathway. These findings give an innovative insight into the association of PPARα, autophagy, the activation of HSCs and hepatic fibrosis induced by As₂O₃.

Braving the Element: Pancreatic β-Cell Dysfunction and Adaptation in Response to Arsenic Exposure

Type 2 diabetes mellitus (T2DM) is a serious global health problem, currently affecting an estimated 451 million people worldwide. T2DM is characterized by hyperglycemia and low insulin relative to the metabolic demand. The precise contributing factors for a given individual vary, but generally include a combination of insulin resistance and insufficient insulin secretion. Ultimately, the progression to diabetes occurs only after β-cells fail to meet the needs of the individual. The stresses placed upon β-cells in this context manifest as increased oxidative damage, local inflammation, and ER stress, often inciting a destructive spiral of β-cell death, increased metabolic stress due to further insufficiency, and additional β-cell death. Several pathways controlling insulin resistance and β-cell adaptation/survival are affected by a class of exogenous bioactive compounds deemed endocrine disrupting chemicals (EDCs). Epidemiological studies have shown that, in several regions throughout the world, exposure to the EDC inorganic arsenic (iAs) correlates significantly with T2DM. It has been proposed that a lifetime of exposure to iAs may exacerbate problems with both insulin sensitivity as well as β-cell function/survival, promoting the development of T2DM. This review focuses on the mechanisms of iAs action as they relate to known adaptive and maladaptive pathways in pancreatic β-cells.

Dysregulation of Sqstm1, mitophagy, and apoptotic genes in chronic exposure to arsenic and high-fat diet (HFD)

Arsenic (As) is a toxic and hazardous metalloid. Unfortunately, its presence in drinking water together with wrong nutritional patterns is associated with an increase in the occurrence of metabolic disorders in young people. Degradation of mitochondria is presented by a specific form of autophagy called mitophagy which is an important landmark leading to apoptosis during lipotoxicity. Lipotoxicity and cellular toxicity due to arsenic intake can lead to changes in mitophagy and apoptosis. The protein derived from SQSTM1 gene, also called p62, plays an important role in energy homeostasis in the liver, and it can contribute to the regulation of autophagic responses given its effect on signaling of mTOR, MAPK, and NF-KB. Consequently, changes in Sqstm1, mitophagy (BNIP3), and apoptotic (caspase 3) genes in the livers of NMRI mice were examined with the use of real-time RT-PCR Array followed by exposure to an environmentally relevant and negligible cytotoxic concentration of arsenite (50 ppm) in drinking water while being fed with a high-fat diet (HFD) or low-fat diet (LFD) for 20 weeks (LFD-As and HFD-As groups). While LFD-As and HFD groups showed a decrease in BNIP3 expression, a significant increase was observed in the HFD-As group. P62 gene showed downregulation in LFD-As and HFD groups, and upregeneration was observed in the HFD-As group. Caspase 3 showed increased expression as the key factor associated with apoptotic liver cell death in the three groups, with the highest value in HFD-As group. Overall, the changes observed in the expression of Sqstm1, BNIP3, and caspase 3 in this study can be related to the level of liver damage caused by exposure to arsenic and HFD and probably, BNIP3 pro-apoptotic protein is associated with an increased cell death due to HFD and As.

Taurine improves low-level inorganic arsenic-induced insulin resistance by activating PPARγ-mTORC2 signalling and inhibiting hepatic autophagy

Inorganic arsenic (iAs) is reportedly associated with the increased incidence of type 2 diabetes in the population. Here, we found that iAs exposure significantly decreased the expression of glycolytic genes and glycogen content and increased gluconeogenesis gene levels in C57/BL6J mice. The expression of peroxisome proliferator-activated receptor γ (PPARγ), and mechanistic target of rapamycin complex 2 (mTORC2) were decreased in the livers of iAs-treated mice. Furthermore, in iAs-treated HepG2 cells, we found that PPARγ agonist rosiglitazone (RGS) increased the expression of mTORC2, inhibited autophagy, and improved glucose metabolism. mTORC2 agonist palmitic acid inhibited autophagy and improved glucose metabolism as well as the autophagosome formation inhibitor 3-methyladenine. Taurine, a natural compound, reversed impaired glucose metabolism and decreased expression of PPARγ and mTORC2 induced by iAs in mice liver and HepG2 cells. These data indicated that taurine administration could ameliorate iAs-induced insulin resistance through activating PPARγ-mTORC2 signalling and subsequently inhibiting hepatic autophagy.

Taurine Attenuates As2O3-Induced Autophagy in Cerebrum of Mouse Through Nrf2 Pathway

We previously reported that the impairment of cerebrum may relate with neurotoxicity induced by arsenic (As) exposure. In the present study, we investigated whether autophagy of the cerebrum neurons were responsible for As-induced neurotoxicity and the protective role of taurine (Tau). Forty mice were randomly divided into control group, Tau control group, As exposure group and Tau protection group. The results showed that LC3 II expression was elevated and P62 expression was lower after As exposure, whereas the effects were obviously attenuated by Tau treatment. More important, As induced increase of MDA level and decrease of Nrf2 expression were significantly inversed in protective group. In sum, autophagy inhibition might play a strong role in the neuroprotection of Tau in As-induced toxicity via Nrf2 pathway.

HPLC Determination of Bioactive Sulfur Compounds, Amino Acids and Biogenic Amines in Biological Specimens

There is an increasing interest for analytical methods aimed to detect biological sulfur-containing amines, because of their involvement in human diseases and metabolic disorders. This work describes an improved HPLC method for the determination of sulfur containing amino acids and amines from different biological matrices. We optimized a pre-column derivatization procedure using dabsyl chloride, in which dabsylated products can be monitored spectrophotometrically at 460 nm. This method allows the simultaneous analysis of biogenic amines, amino acids and sulfo-amino compounds including carnosine, dopamine, epinephrine, glutathione, cysteine, taurine, lanthionine, and cystathionine in brain specimens, urines, plasma, and cell lysates. Moreover, the method is suitable for the study of physiological and non-physiological derivatives of taurine and glutathione such as hypotaurine, homotaurine, homocysteic acid and S-acetylglutathione. The present method displays good efficiency of derivatization, having the advantage to give rise to stable products compared to other derivatizing agents such as o-phthalaldehyde and dansyl chloride.With this method, we provide a tool to study sulfur cycle from a metabolic point of view in relation to the pattern of biological amino-compounds, allowing researchers to get a complete scenario of organic sulfur and amino metabolism in tissues and cells.

Taurine Normalizes the Levels of Se, Cu, Fe in Mouse Liver and Kidney Exposed to Arsenic Subchronically

To evaluate the benefits of taurine on the homeostasis of trace elements induced by toxic metals, we investigated the concentration of Selenium (Se), Copper (Cu), Iron (Fe) and Manganese (Mn) in mouse liver and kidney after arsenic exposure for 2 months. The experimental animals were divided into control group, arsenic exposure group (1, 2, 4 ppm) and taurine protective group randomly. Concentrations of serum, liver and kidney trace elements such as Se, Cu, Fe, Mn were measured by Inductively Coupled Plasma-Mass Spectrometry. Our results showed that the concentration of Cu was higher, however, the concentration of Se and Fe was lower in mice liver and kidney exposed to arsenic. The levels of Se, Cu, Fe were alleviated by co-administered with taurine. Furthermore, there was no difference in the concentration of Mn between the three groups. Our finding suggests that taurine may relieve the disturbed levels of Se, Cu and Fe in liver and kidney induced by arsenic.

Taurine attenuates arsenic-induced pyroptosis and nonalcoholic steatohepatitis by inhibiting the autophagic-inflammasomal pathway

Arsenic exposure causes nonalcoholic steatohepatitis (NASH). Inflammation is a key contributor to the pathology of nonalcoholic fatty liver disease (NAFLD), including NASH. However, it is unclear how arsenic induces inflammation. In mouse livers, we show that arsenic trioxide (As₂O₃) induced NASH, increased autophagy and NLRP3 inflammasome activation, increased lipid accumulation, and resulted in dysregulation of lipid-related genes. Supplemented with taurine (Tau) attenuated the inflammation and autophagy caused by As₂O₃. In HepG2 cells, we found that As₂O₃-induced pyroptotic cell death was dependent upon the activation of NLRP3 inflammasome, which was CTSB-dependent. In addition, inhibiting autophagy alleviated the As₂O₃-induced increase of cytosolic CTSB expression and subsequent release of LDH, activation of the NLRP3 inflammasome, and pyroptosis. Moreover, we found that Tau alleviated As₂O₃-induced elevation of autophagy, CTSB expression, and activation of the NLRP3 inflammasome, and reduced the release of LDH, pyroptotic cell death, and inflammation. Interestingly, As₂O₃-induced lipid accumulation could not be alleviated by either inhibition of autophagy nor by inhibition of CTSB. Additionally, neither inhibition of the NLRP3 inflammasome or Tau treatment could alleviate lipid accumulation. These results demonstrated that As₂O₃-induced pyroptosis involves autophagy, CTSB, and the NLRP3 inflammasome cascade, and that Tau alleviates As₂O₃-induced liver inflammation by inhibiting the autophagic-CTSB-NLRP3 inflammasomal pathway rather than decreasing lipid accumulation. These findings give insight into the association of autophagy, inflammation, pyroptosis, and NASH induced by As₂O₃.

WITHDRAWN: Toxic effects of gestational arsenic trioxide on the neuroendocrine axis of developing rats

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Autophagy upregulation as a possible mechanism of arsenic induced diabetes

The key features of type 2 diabetes mellitus (T2DM) caused by high fat diet (HFD) in combination with arsenic (As) exposure (pronounced glucose intolerance despite a significant decrease in insulin resistance) are different from those expected for T2DM. Autophagy has been considered as a possible link between insulin resistance and obesity. Therefore in this study, we utilized autophagy gene expression profiling via real-time RT-PCR array analysis in livers of NMRI mice exposed to an environmentally relevant and minimally cytotoxic concentration of arsenite (50 ppm) in drinking water while being fed with a HFD for 20 weeks. Out of 84 genes associated with autophagy under study, 21 genes were related to autophagy machinery components of which 13 genes were downregulated when HDF diet was applied. In this study, for the first time, it was shown that the exposure to arsenic in the livers of mice chronically fed with HFD along with increased oxidative stress resulted in the restoration of autophagy [upregulation of genes involved in the early phase of phagophore formation, phagophore expansion and autophagosome-lysosome linkage stages]. Considering the role of arsenic in the induction of autophagy; it can be argued that reduced insulin resistance in HFD - As induced diabetes may be mediated by autophagy upregulation.

Effects and Mechanisms of Taurine as a Therapeutic Agent

Taurine is an abundant, β-amino acid with diverse cytoprotective activity. In some species, taurine is an essential nutrient but in man it is considered a semi-essential nutrient, although cells lacking taurine show major pathology. These findings have spurred interest in the potential use of taurine as a therapeutic agent. The discovery that taurine is an effective therapy against congestive heart failure led to the study of taurine as a therapeutic agent against other disease conditions. Today, taurine has been approved for the treatment of congestive heart failure in Japan and shows promise in the treatment of several other diseases. The present review summarizes studies supporting a role of taurine in the treatment of diseases of muscle, the central nervous system, and the cardiovascular system. In addition, taurine is extremely effective in the treatment of the mitochondrial disease, mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS), and offers a new approach for the treatment of metabolic diseases, such as diabetes, and inflammatory diseases, such as arthritis. The review also addresses the functions of taurine (regulation of antioxidation, energy metabolism, gene expression, ER stress, neuromodulation, quality control and calcium homeostasis) underlying these therapeutic actions.

Taurine ameliorates particulate matter-induced emphysema by switching on mitochondrial NADH dehydrogenase genes

Exposure to high levels of particulate matter (PM) poses a major threat to human health. Cigarette smoke is the most common irritant that causes chronic obstructive pulmonary disease (COPD); however, at least one-fourth of patients with COPD are nonsmokers, and their disease is largely attributed to air pollution. The occurrence of pollution episodes in China has raised an emergent question of how PM leads to the pathogenesis of COPD. In this paper, we show that deregulation of mitochondrial NADH dehydrogenase gene expression levels plays a key role in the aggravation of COPD during air pollutant exposure, which can be rescued by taurine and 3-MA treatments in both mammalian cells and animals.

Chronic obstructive pulmonary disease (COPD) has been linked to particulate matter (PM) exposure. Using transcriptomic analysis, we demonstrate that diesel exhaust particles, one of the major sources of particulate emission, down-regulated genes located in mitochondrial complexes I and V and induced experimental COPD in a mouse model. 1-Nitropyrene was identified as a major toxic component of PM-induced COPD. In the panel study, COPD patients were found to be more susceptible to PM than individuals with normal lung function due to an increased inflammatory response. Mechanistically, exposure to PM in human bronchial epithelial cells led to a decline in CCAAT/enhancer-binding protein alpha (C/EBPα), which triggered aberrant expression of NADH dehydrogenase genes and ultimately led to enhanced autophagy. ATG7-deficient mice, which have lower autophagy rates, were protected from PM-induced experimental COPD. Using metabolomics analysis, we further established that treatment with taurine and 3-methyladenine completely restored mitochondrial gene expression levels, thereby ameliorating the PM-induced emphysema. Our studies suggest a potential therapeutic intervention for the C/EBPα/mitochondria/autophagy axis in PM-induced COPD.