Purinergic receptor X7 is a key modulator of metabolic oxidative stress-mediated autophagy and inflammation in experimental nonalcoholic steatohepatitis

Recent studies indicate that metabolic oxidative stress, autophagy, and inflammation are hallmarks of nonalcoholic steatohepatitis (NASH) progression. However, the molecular mechanisms that link these important events in NASH remain unclear. In this study, we investigated the mechanistic role of purinergic receptor X7 (P2X7) in modulating autophagy and resultant inflammation in NASH in response to metabolic oxidative stress. The study uses two rodent models of NASH. In one of them, a CYP2E1 substrate bromodichloromethane is used to induce metabolic oxidative stress and NASH. Methyl choline-deficient diet feeding is used for the other NASH model. CYP2E1 and P2X7 receptor gene-deleted mice are used to establish their roles in regulating metabolic oxidative stress and autophagy. Autophagy gene expression, protein levels, confocal microscopy based-immunolocalization of lysosome-associated membrane protein (LAMP)2A and histopathological analysis were performed. CYP2E1-dependent metabolic oxidative stress induced increases in P2X7 receptor expression and chaperone-mediated autophagy markers LAMP2A and heat shock cognate 70 but caused depletion of light chain 3 isoform B (LC3B) protein levels. P2X7 receptor gene deletion significantly decreased LAMP2A and inflammatory indicators while significantly increasing LC3B protein levels compared with wild-type mice treated with bromodichloromethane. P2X7 receptor-deleted mice were also protected from NASH pathology as evidenced by decreased inflammation and fibrosis. Our studies establish that P2X7 receptor is a key regulator of autophagy induced by metabolic oxidative stress in NASH, thereby modulating hepatic inflammation. Furthermore, our findings presented here form a basis for P2X7 receptor as a potential therapeutic target in the treatment for NASH.

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Micro-RNA 21 inhibition of SMAD7 enhances fibrogenesis via leptin-mediated NADPH oxidase in experimental and human nonalcoholic steatohepatitis

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00346.2014 ◽

2015 ◽

Vol 308 (4) ◽

pp. G298-G312 ◽

Cited By ~ 72

Author(s):

Diptadip Dattaroy ◽

Sahar Pourhoseini ◽

Suvarthi Das ◽

Firas Alhasson ◽

Ratanesh Kumar Seth ◽

...

Keyword(s):

Oxidative Stress ◽

Nadph Oxidase ◽

Nonalcoholic Steatohepatitis ◽

Molecular Mechanisms ◽

Transforming Growth Factor ◽

Micro Rna ◽

Protein Levels ◽

Significant Research ◽

Human Livers

Hepatic fibrosis in nonalcoholic steatohepatitis (NASH) is the common pathophysiological process resulting from chronic liver inflammation and oxidative stress. Although significant research has been carried out on the role of leptin-induced NADPH oxidase in fibrogenesis, the molecular mechanisms that connect the leptin-NADPH oxidase axis in upregulation of transforming growth factor (TGF)-β signaling have been unclear. We aimed to investigate the role of leptin-mediated upregulation of NADPH oxidase and its subsequent induction of micro-RNA 21 (miR21) in fibrogenesis. Human NASH livers and a high-fat (60% kcal) diet-fed chronic mouse model, where hepatotoxin bromodichloromethane was used to induce NASH, were used for this study. To prove the role of the leptin-NADPH oxidase-miR21 axis, mice deficient in genes for leptin, p47phox, and miR21 were used. Results showed that wild-type mice and human livers with NASH had increased oxidative stress, increased p47phox expression, augmented NF-κB activation, and increased miR21 levels. These mice and human livers showed increased TGF-β, SMAD2/3-SMAD4 colocalizations in the nucleus, increased immunoreactivity against Col1α, and α-SMA with a concomitant decrease in protein levels of SMAD7. Mice that were deficient in leptin or p47phox had decreased activated NF-κB and miR21 levels, suggesting the role of leptin and NADPH oxidase in inducing NF-κB-mediated miR21 expression. Further miR21 knockout mice had decreased colocalization events of SMAD2/3-SMAD4 in the nucleus, increased SMAD7 levels, and decreased fibrogenesis. Taken together, the studies show the novel role of leptin-NADPH oxidase induction of miR21 as a key regulator of TGF-β signaling and fibrogenesis in experimental and human NASH.

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P2X7 Receptor as a Key Player in Oxidative Stress-Driven Cell Fate in Nonalcoholic Steatohepatitis

Oxidative Medicine and Cellular Longevity ◽

10.1155/2015/172493 ◽

2015 ◽

Vol 2015 ◽

pp. 1-7 ◽

Cited By ~ 15

Author(s):

Saurabh Chatterjee ◽

Suvarthi Das

Keyword(s):

Oxidative Stress ◽

Nonalcoholic Steatohepatitis ◽

Purinergic Receptors ◽

Molecular Mechanisms ◽

Inflammatory Responses ◽

Purinergic Receptor ◽

Leptin Resistance ◽

Hepatocellular Injury ◽

Cardiometabolic Disorders

Incidences of nonalcoholic fatty liver disease parallels increase in the global obesity epidemic. NAFLD has been shown to be associated with risks of cardiometabolic disorders and kidney disturbances. It is accompanied by insulin and leptin resistance that complicate the diagnosis and treatment of this public health menace. Though significant research is underway for understanding the molecular mechanisms of NAFLD and its subsequent inflammatory and fibrotic manifestations like nonalcoholic steatohepatitis, the role of purinergic receptors has been unclear. It is increasingly being recognized that damage associated molecular patterns like NAD and ATP that are released from injured cells via hepatocellular injury either by oxidative stress or lipotoxicity from steatosis activate the purinergic receptor. Based on evidence from inflammatory responses in the airways and vasculature and autoimmune complications in humans and rodents, it is beyond doubt that hepatocellular inflammation such as that seen in NASH can result from the activation of purinergic receptors. This event can result in the formation of inflammasomes and can be an important pathway for the progression of NASH. The present review evaluates the current knowledge of the role of oxidative stress and its signaling via P2X7 receptors in hepatocellular injury that might contribute to the NASH pathophysiology.

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Relationship between aldose reductase enzyme and the signaling pathway of protein kinase C in an in vitro diabetic retinopathy model

Canadian Journal of Physiology and Pharmacology ◽

10.1139/cjpp-2019-0211 ◽

2020 ◽

Vol 98 (4) ◽

pp. 243-251

Author(s):

Mutlu Sarikaya ◽

Nuray Yazihan ◽

Net Daş Evcimen

Keyword(s):

Oxidative Stress ◽

Protein Kinase C ◽

Protein Kinase ◽

Molecular Mechanisms ◽

Signaling Molecules ◽

Protein Levels ◽

Kinase C ◽

The Relationship ◽

And Oxidative Stress ◽

Expression And Activity

Protein kinase C (PKC) and aldose reductase (AR) enzyme activities are increased in diabetes and complications are include retinopathy, nephropathy, and neuropathy. However, the relationship between PKC and AR and the underlying molecular mechanisms is still unclear. We aimed to evaluate the relationship between these two enzymes and clarify the underlying molecular mechanisms by the related signaling molecules. The effects of hyperglycemia and oxidative stress on AR and PKC enzymes and the signaling molecules such as nuclear factor-kappa B (NF-κB), inhibitor kappa B-alpha (IkB-α), total c-Jun, phospho c-Jun, and stress-activated protein kinases (SAPK)/Jun amino-terminal kinases (JNK) were evaluated in human retinal pigment epithelial cells (ARPE-19). AR, PKC protein levels, and related signaling molecules increased with hyperglycemia and oxidative stress. The AR inhibitor sorbinil decreased PKC expression and activity and all signaling molecule protein levels. Increased AR expression during hyperglycemia and oxidative stress was found to be correlated with the increase in PKC expression and activity in both conditions. Decreased expression and activity of PKC and the protein levels of related signaling molecules with the AR inhibitor sorbinil showed that AR enzyme may play a key role in the expression of PKC enzyme and oxidative stress during diabetes.

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Deficiency of the Purinergic Receptor 2X7 Attenuates Nonalcoholic Steatohepatitis Induced by High-Fat Diet: Possible Role of the NLRP3 Inflammasome

Oxidative Medicine and Cellular Longevity ◽

10.1155/2017/8962458 ◽

2017 ◽

Vol 2017 ◽

pp. 1-14 ◽

Cited By ~ 5

Author(s):

Claudia Blasetti Fantauzzi ◽

Stefano Menini ◽

Carla Iacobini ◽

Chiara Rossi ◽

Eleonora Santini ◽

...

Keyword(s):

Nonalcoholic Steatohepatitis ◽

Nlrp3 Inflammasome ◽

High Fat Diet ◽

Molecular Mechanisms ◽

Purinergic Receptor ◽

High Fat ◽

Liver Sinusoidal Endothelial Cells ◽

Nonalcoholic Fatty Liver ◽

Markers Of Inflammation

Molecular mechanisms driving transition from simple steatosis to nonalcoholic steatohepatitis (NASH), a critical step in the progression of nonalcoholic fatty liver disease (NAFLD) to cirrhosis, are poorly defined. This study aimed at investigating the role of the purinergic receptor 2X7 (PR2X7), through the NLRP3 inflammasome, in the development of NASH. To this end, mice knockout for the Pr2x7 gene (Pr2x7−/−) and coeval wild-type (WT) mice were fed a high-fat diet (HFD) or normal-fat diet for 16 weeks. NAFLD grade and stage were lower in Pr2x7−/− than WT mice, and only 1/7 Pr2x7−/− animals showed evidence of NASH, as compared with 4/7 WT mice. Molecular markers of inflammation, oxidative stress, and fibrosis were markedly increased in WT-HFD mice, whereas no or significantly reduced increments were detected in Pr2x7−/− animals, which showed also decreased modulation of genes of lipid metabolism. Deletion of Pr2x7 gene was associated with blunted or abolished activation of NLRP3 inflammasome and expression of its components, which were induced in liver sinusoidal endothelial cells challenged with appropriate stimuli. These data show that Pr2x7 gene deletion protects mice from HFD-induced NASH, possibly through blunted activation of NLRP3 inflammasome, suggesting that PR2X7 and NLRP3 may represent novel therapeutic targets.

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Insulin Receptor and its Relationship with Different Forms of Insulin Resistance

Advances in Cell Biology ◽

10.2478/v10052-010-0004-8 ◽

2010 ◽

Vol 2 (2) ◽

pp. 59-90 ◽

Cited By ~ 1

Author(s):

Aleksandra Rojek ◽

Marek Niedziela

Keyword(s):

Insulin Resistance ◽

Insulin Receptor ◽

Molecular Mechanisms ◽

Receptor Gene ◽

Insulin Receptors ◽

Receptor Expression ◽

Insulin Receptor Gene ◽

Efficient Treatment ◽

Regulatory Processes ◽

Stage Of Development

SummaryInsulin plays an important role in maintaining the whole organism’s homeostasis. The presence of insulin receptors in all vertebrates and invertebrates cells reflects the diversity of regulatory processes in which this hormone is involved. Furthermore, many different factors may influence the level of insulin receptor expression. These factors include e.g. the sole insulin or stage of development. Mutations in the receptor may lead to the development of insulin resistance. These mutations differ in the level of severity and are frequently associated with diabetes mellitus, hypertension, cardiovascular disorders, heart failure, metabolic syndrome and infertility in women. More than 50 mutations in insulin receptor gene have already been characterized. These mutations are associated with rare forms of insulin resistance like leprechaunism, insulin resistance type A or Rabson-Mendenhall syndrome. Molecular analysis of insulin receptor gene may lead to a better understanding of molecular mechanisms underlying various types of insulin resistance and help to develop more efficient treatment.

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A Review of Oxidative Stress Products and Related Genes in Early Alzheimer’s Disease

Journal of Alzheimer s Disease ◽

10.3233/jad-210497 ◽

2021 ◽

pp. 1-25

Author(s):

Federica Cioffi ◽

Rayan Hassan Ibrahim Adam ◽

Ruchi Bansal ◽

Kerensa Broersen

Keyword(s):

Oxidative Stress ◽

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Molecular Mechanisms ◽

Early Stage ◽

Disease Status ◽

Diagnostic Value ◽

Oxidation Products ◽

Protein Levels ◽

Stress Levels

Oxidative stress is associated with the progression of Alzheimer’s disease (AD). Reactive oxygen species can modify lipids, DNA, RNA, and proteins in the brain. The products of their peroxidation and oxidation are readily detectable at incipient stages of disease. Based on these oxidation products, various biomarker-based strategies have been developed to identify oxidative stress levels in AD. Known oxidative stress-related biomarkers include lipid peroxidation products F2-isoprostanes, as well as malondialdehyde and 4-hydroxynonenal which both conjugate to specific amino acids to modify proteins, and DNA or RNA oxidation products 8-hydroxy-2’-deoxyguanosine (8-OHdG) and 8-hydroxyguanosine (8-OHG), respectively. The inducible enzyme heme oxygenase type 1 (HO-1) is found to be upregulated in response to oxidative stress-related events in the AD brain. While these global biomarkers for oxidative stress are associated with early-stage AD, they generally poorly differentiate from other neurodegenerative disorders that also coincide with oxidative stress. Redox proteomics approaches provided specificity of oxidative stress-associated biomarkers to AD pathology by the identification of oxidatively damaged pathology-specific proteins. In this review, we discuss the potential combined diagnostic value of these reported biomarkers in the context of AD and discuss eight oxidative stress-related mRNA biomarkers in AD that we newly identified using a transcriptomics approach. We review these genes in the context of their reported involvement in oxidative stress regulation and specificity for AD. Further research is warranted to establish the protein levels and their functionalities as well as the molecular mechanisms by which these potential biomarkers are involved in regulation of oxidative stress levels and their potential for determination of oxidative stress and disease status of AD patients.

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Abstract P055: Systemic Arterial Hypertension Induces Pulmonary Injury Beyond Protein Degradation and Atrophy of Diaphragm

Hypertension ◽

10.1161/hyp.66.suppl_1.p055 ◽

2015 ◽

Vol 66 (suppl_1) ◽

Author(s):

Pamella R Souza ◽

Rodolfo P Vieira ◽

Karin Flues ◽

Wilson M De-Moraes ◽

Janaína B Ferreira ◽

...

Keyword(s):

Arterial Hypertension ◽

Protein Degradation ◽

P2x7 Receptor ◽

Purinergic Receptor ◽

Ubiquitin Proteasome System ◽

Receptor Expression ◽

Diaphragm Muscle ◽

Type I ◽

Systemic Arterial Hypertension ◽

Ubiquitin Proteasome

Background: Systemic arterial hypertension (SAH) is a chronic disease associated with systemic inflammation. Although cardiovascular adaptations resulting from SAH are more evident, little is known about the respiratory alterations. The purinergic receptor P2X7 plays a key role in the immune modulation, beyond to control the vascular tone and the development of inflammation and fibrosis. Aims: Evaluate the effects of SAH on the pulmonary inflammation and remodeling and on the diaphragm, and the involvement of purinergic receptor P2X7 and of ubiquitin-proteasome system (UPS) in this response. Methods: Spontaneously hypertensive rats (SHR) and normotensive Wistar (N) with 18 weeks-of-age were evaluated for: inflammation and remodeling of airways and pulmonary vessels and for P2X7 receptor expression. The morphology and biochemistryin diaphragm muscle for myosin ATPase reaction and ubiquitin-proteasome system (UPS), respectively. Results: The SHR showed a higher wall/lumen of the pulmonary arteries, as well as increased collagen deposition on the wall of these arteries. Increase in P2X7 receptor expression in pulmonary vascular wall (SHR:4.3%±0.7% vs. N:0.3%±0.2%) and bronchial epithelial (SHR:29±0% vs 2.8% N:10.5%±1.3%). The diaphragm was increased cross-sectional area (CSA) of type I fibers (16%) and reduction in CSA of type II (41%), increased the UPS activity and lipid peroxidation. SHR did not change in the analysis of ubiquitinated proteins and misfolded proteins. Conclusion: SAH induces important pulmonary disorders such pulmonary vascular remodeling, with increased expression of the purinergic receptor P2X7 associated with atrophy and protein degradation on diaphragm.

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Expression of the Mature Luteinizing Hormone Receptor in Rodent Urogenital and Adrenal Tissues Is Developmentally Regulated at a Posttranslational Level

Endocrinology ◽

10.1210/en.2005-0073 ◽

2005 ◽

Vol 146 (8) ◽

pp. 3224-3232 ◽

Cited By ~ 30

Author(s):

Pirjo M. Apaja ◽

Jyrki T. Aatsinki ◽

Hannu J. Rajaniemi ◽

Ulla E. Petäjä-Repo

Keyword(s):

Adrenal Glands ◽

Receptor Gene ◽

Receptor Expression ◽

Luteinizing Hormone Receptor ◽

Lacz Reporter ◽

Developmentally Regulated ◽

Lh Receptor ◽

Protein Levels ◽

Functional Maturation ◽

G Protein Coupled

Abstract The LH receptor (LHR) is a G protein-coupled receptor involved in the regulation of ovarian and testicular functions. In this study we demonstrate novel and unexpected patterns of receptor expression and regulation in fetal and adult rodent urogenital and adrenal tissues. Two rat LHR promoter fragments (∼2 and 4 kb) were shown to direct expression of the lacZ reporter in transgenic mice to gonads, adrenal glands, and kidneys, starting at 14.5 d post coitum, and to genital tubercles, starting at 11.5 d post coitum. These tissues were also found to express the full-length LHR mRNA and protein during rat fetal development, but, importantly, only immature receptors carrying unprocessed N-linked glycans were detected. After birth, the receptor gene activity ceased, except in the gonads, which started to express the mature receptor carrying fully processed N-linked glycans. Surprisingly, both LHR mRNA and mature protein levels were up-regulated substantially in pregnant female adrenal glands and kidneys at a time that coincides with differentiation of fetal urogenital tissues. Taken together, these results indicate that the LHR protein is expressed constitutively in gonadal and nongonadal urogenital tissues as well in adrenal glands, but its final functional maturation at the posttranslational level appears to be developmentally and physiologically regulated.

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Cerebrovascular ETB, 5-HT1B, and AT1 receptor upregulation correlates with reduction in regional CBF after subarachnoid hemorrhage

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.00857.2007 ◽

2007 ◽

Vol 293 (6) ◽

pp. H3750-H3758 ◽

Cited By ~ 48

Author(s):

Saema Ansar ◽

Petter Vikman ◽

Marianne Nielsen ◽

Lars Edvinsson

Keyword(s):

Subarachnoid Hemorrhage ◽

Molecular Mechanisms ◽

Cerebral Arteries ◽

Temporal Correlation ◽

Receptor Expression ◽

Dependent Manner ◽

Ang Ii ◽

Contractile Responses ◽

Protein Levels ◽

Receptor Mrna

We hypothesize that cerebral ischemia leads to enhanced expression of endothelin (ET), 5-hydroxytryptamine (5-HT), and angiotensin II (ANG II) receptors in the vascular smooth muscle cells. Our aim is to correlate the upregulation of cerebrovascular receptors and the underlying molecular mechanisms with the reduction in regional and global cerebral blood flow (CBF) after subarachnoid hemorrhage (SAH). SAH was induced by injecting 250 μl blood into the prechiasmatic cistern in rats. The cerebral arteries were removed 0, 1, 3, 6, 12, 24, and 48 h after the SAH for functional and molecular studies. The contractile responses to ET-1, 5-carboxamidotryptamine (5-CT), and ANG II were investigated with myograph. The receptor mRNA and protein levels were analyzed by quantitative real-time PCR and immunohistochemistry, respectively. In addition, regional and global CBFs were measured by an autoradiographic method. As a result, SAH resulted in enhanced contractions to ET-1 and 5-CT. ANG II [via ANG II type 1 (AT1) receptors] induced increased contractile responses [in the presence of the ANG II type 2 (AT2) receptor antagonist PD-123319]. In parallel the ETB, 5-HT1B, and AT1 receptor, mRNA and protein levels were elevated by time. The regional and global CBF showed a successive reduction with time after SAH. In conclusion, the results demonstrate for the first time that SAH induces the upregulation of ETB, 5-HT1B, and AT1 receptors in a time-dependent manner both at functional, mRNA, and protein levels. These changes occur in parallel with a successive decrease in CBF. Thus there is a temporal correlation between the changes in receptor expression and CBF reduction, suggesting a linkage.

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Reducing sarcolipin expression improves muscle metabolism in mdx mice

AJP Cell Physiology ◽

10.1152/ajpcell.00125.2021 ◽

2022 ◽

Author(s):

Rekha Balakrishnan ◽

Satvik Mareedu ◽

Gopal J. Babu

Keyword(s):

Oxidative Stress ◽

Muscle Metabolism ◽

Muscle Pathology ◽

Mdx Mouse ◽

Mdx Mice ◽

Histopathological Analysis ◽

Protein Levels ◽

Insulin Tolerance ◽

Complex Protein ◽

Muscle Wasting Disease

Duchenne muscular dystrophy (DMD) is an inherited muscle wasting disease. Metabolic impairments and oxidative stress are major secondary mechanisms that severely worsen muscle function in DMD. Here, we sought to determine whether germline reduction or ablation of sarcolipin (SLN), an inhibitor of sarco/endoplasmic reticulum (SR) Ca2+ ATPase (SERCA) improves muscle metabolism and ameliorates muscle pathology in the mdx mouse model of DMD. Glucose and insulin tolerance tests show that glucose clearance rate and insulin sensitivity were improved in the SLN haploinsufficient mdx (mdx:sln+/-) and SLN deficient mdx (mdx:sln-/-) mice. The histopathological analysis shows that fibrosis and necrosis were significantly reduced in muscles of mdx:sln+/- and mdx:sln-/- mice. SR Ca2+ uptake, mitochondrial complex protein levels, complex activities, mitochondrial Ca2+ uptake and release, and mitochondrial metabolism were significantly improved and, lipid peroxidation and protein carbonylation were reduced in the muscles of mdx:sln+/- and mdx:sln-/- mice. These data demonstrate that reduction or ablation of SLN expression can improve muscle metabolism, reduce oxidative stress, decrease muscle pathology, and protects the mdx mice from glucose intolerance.

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