Oxidative stress induces the endoplasmic reticulum stress and facilitates inclusion formation in cultured cells

A Novel ⋅OH-Monitor ER-Targeted Probe to Expose the Function of Sorafenib

The hydroxyl radical (⋅OH), widely recognized as the most potent free radical, plays a crucial role in numerous physiological and pathological pathways due to its strong oxidizability.Ferroptosis, as a novel mode of cell death, is initiated by the accumulation of iron-dependent lipid peroxidation. Among them, ⋅OH as the original reactive oxygen species (ROSs)is mass-produced due to Fenton reaction in vivo and closely related to cancer treatment.Besides, endoplasmic reticulum (ER) as a membrane-rich structure organelle, is a crucial organelle in all eukaryotes where excessive expression of ROSs, including ⋅OH can triggerER stress which was reported thatwasclosely related toferroptosis. So developing a new probe for their interrelationship research is important. In this paper, we constructed a1,8-naphthalimide-based ER-targeted fluorescence probe named M-1 to monitor ⋅OH variation in vitro and vivo. What's more, we achieved the monitor of ⋅OH during ER stress andferroptosis processesin cancer cells, andfurther explored the important role of ER stress and ferroptosis processes in SF (sorafenib) involved cancer cells.

Chlamydia trachomatis upregulates lncRNA CYTOR to mediate autophagy through miR-206/MAPK1 axis

Chlamydia trachomatis infection can be regulated by autophagy-related genes. LncRNA CYTOR has been proven to be involved in autophagy. In this research, we investigated the role of CYTOR in autophagy induced by C. trachomatis and the potential mechanisms. After C. trachomatis infection, CYTOR and MAPK1 were up-regulated and miR-206 was down-regulated, meanwhile, the autophagy-related protein Beclin1 and LC3-Ⅱ/LC3-Ⅰ ratio were increased. Interference with CYTOR or overexpression with miR-206 downregulated the autophagy-related protein Beclin1 and the number of autophagic spots LC3, decreased the protein ratio of LC3-II/LC3-I, and upregulated the expression of P62 protein. The luciferase reporter assay confirmed that CYTOR acted as a sponge for miR-206 to target MAPK1. In addition, CYTOR promoted autophagy induced by C. trachomatis infection through the MAPK1/ERK signaling pathway activation. Taken together, we have identified a novel molecular mechanism that the CYTOR/miR-206/MAPK1 axis was involved in the regulation of autophagy in C. trachomatis infection. This work provides an experimental basis for elucidating the pathogenesis of C. trachomatis for the treatment, prevention and control of related infectious diseases.

Pathogenetic Pathways in Nonalcoholic Fatty Liver Disease: An Incomplete Jigsaw Puzzle

Nonalcoholic fatty liver disease (NAFLD)-a condition of excess fat accumulation in hepatocytes associated with metabolic dysfunction-has surpassed viral hepatitis to become the most prevalent chronic liver disease worldwide. As of now, only modestly effective pharmacological therapies for NAFLD exist. The uncomplete understanding of the pathophysiology underlying the heterogeneous disease spectrum known as NAFLD remains one of the major obstacles to the development of novel therapeutic approaches. This review compiles current knowledge on the principal signaling pathways and pathogenic mechanisms involved in NAFLD, which are analyzed in relation to its main pathological hallmarks (ie, hepatic steatosis, steatohepatitis, and liver fibrosis).

The use of selenomethionine to reduce ammonia toxicity in porcine spleen by inhibiting endoplasmic reticulum stress and autophagy mediated by oxidative stress

Ammonia (NH3) is a typical pollutant in the atmosphere and is well known for its harmful effects on plants, animals as well as human health. Previous studies have shown that NH3 exposure can cause damage to immune organs and impaired immune function in animals. Selenomethionine is a kind of organic selenium, which can not only promote the growth and development of the body, but also inhibit the generation of intracellular reactive oxygen species (ROS), and effectively improve the immune function of the body. Therefore, this study evaluated the toxic effect of NH3 exposure on spleen from a new perspective and investigated the protective effect of selenomethionine on ammonia-induced immunotoxicity. Twenty-four Large White*Duroc*Min pigs were randomly assigned to 4 groups: control group, NH3 group, selenium group, and NH3 + selenium group. Our results showed that NH3 inhalation caused autophagy in the pig spleen, a decrease in lymphocytes, and an increase in autophagic vesicles. Also, NH3 exposure led to a decrease in the activity of some antioxidant enzymes (decreased by about 50%) and a significant increase in the expression of genes related to oxidative stress and endoplasmic reticulum stress (ERS). Our results indicated that selenomethionine mitigated ammonia toxicity in pigs (alleviated about 20-55%). In summary, our findings should be of value in providing a theoretical basis for revealing the toxicity of the high-risk gas NH3, and providing a new perspective on the mechanism of Se against toxic substances.

Effects of Edible Insect Tenebrio molitor Larva Fermentation Extract as a Substitute Protein on Hepatosteatogenesis and Proteomic Changes in Obese Mice Induced by High-Fat Diet

Mealworms (Tenebrio molitor larva) are an edible insect and a protein-rich food; however, research on mealworms as a substitute protein is insufficient. In this study, mealworm fermentation extract (TMP) was assessed as a replacement for soy protein (SP) in a control diet (CON) or a high-fat diet (HFD) of mice for 12 weeks. TMP substitution reduced body weight, body weight gain, body fat mass (perirenal and mesenteric), fat size, glucose intolerance, and insulin resistance compared to the HFD-SP group. TMP alleviated hepatic steatosis (lipid contents and lipid droplets) in high-fat-fed mice and down-regulated the PPARγ, CD36, and DGAT2 gene levels. Proteomic analysis showed that a HFD for 12 weeks up-regulated 20 proteins and down-regulated 17 proteins in mice fed SP. On the other hand, TMP reversed the protein profiles. TMP significantly down-regulated KHK, GLO1, ATP5H, SOD, and DDAH1 and up-regulated DLD, Mup1, CPS1, Ces3b, PDI, and HYOU1 compared to the HFD-SP group. These proteins are involved in the glucose, lipid, and amino acid metabolism, as well as in oxidative stress and endoplasmic reticulum stress. Thus, substituting SP for TMP helped improve HFD-induced obesity, steatosis, and insulin resistance in mice. These results suggest that TMP is a potential substitute for commonly used protein sources.

Correlation of hepatitis C virus-mediated endoplasmic reticulum stress with autophagic flux impairment and hepatocarcinogenesis

Hepatitis C virus (HCV) infection has been known to use autophagy for its replication. However, the mechanisms by which HCV modulates autophagy remain controversial. We used HCV-Japanese fulminant hepatitis-1-infected Huh7 cells. HCV infection induced the accumulation of autophagosomes. Morphological analyses of monomeric red fluorescent protein (mRFP)-green fluorescent protein (GFP) tandem fluorescent-tagged LC3 transfection showed HCV infection impaired autophagic flux. Autophagosome-lysosome fusion assessed by transfection of mRFP- or GFP-LC3 and immunostaining of lysosomal-associated membrane protein 1 was inhibited by HCV infection. Decrease of HCV-induced endoplasmic reticulum (ER) stress by 4-phenylbutyric acid, a chemical chaperone, improved the HCV-mediated autophagic flux impairment. HCV infection-induced oxidative stress and subsequently DNA damage, but not apoptosis. Furthermore, HCV induced cytoprotective effects against the cellular stress by facilitating the formation of cytoplasmic inclusion bodies as shown by p62 expression and by modulating keratin protein expression and activated nuclear factor erythroid 2-related factor 2. HCV eradication by direct-acting antivirals improved autophagic flux, but DNA damage persisted. In conclusion, HCV-induced ER stress correlates with autophagic flux impairment. Decrease of ER stress is considered to be a promising therapeutic strategy for HCV-related chronic liver diseases. However, we should be aware that the risk of hepatocarcinogenesis remains even after HCV eradication.

Zinc Attenuates the Cytotoxicity of Some Stimuli by Reducing Endoplasmic Reticulum Stress in Hepatocytes

Zinc is an essential trace element and plays critical roles in cellular integrity and biological functions. Excess copper induced both oxidative stress and endoplasmic reticulum (ER) stress in liver-derived cultured cells. Excess copper also induced impairment of autophagic flux at the step of autophagosome–lysosome fusion, as well as Mallory–Denk body (MDB)-like inclusion body formation. Zinc ameliorated excess copper-induced impairment of autophagic flux and MDB-like inclusion body formation via the maintenance of ER homeostasis. Furthermore, zinc also ameliorated free fatty acid-induced impairment of autophagic flux. These results indicate that zinc may be able to protect hepatocytes from various ER stress-related conditions.

Efavirenz and Efavirenz-like Compounds Activate Human, Murine, and Macaque Hepatic IRE1α-XBP1

Efavirenz (EFV), a widely used antiretroviral drug, is associated with idiosyncratic hepatotoxicity and dyslipidemia. Here we demonstrate that EFV stimulates the activation in primary hepatocytes of key cell stress regulators: inositol-requiring 1α (IRE1α) and X-box binding protein 1 (XBP1). Following EFV exposure, XBP1 splicing (indicating activation) was increased 35.7-fold in primary human hepatocytes. In parallel, XBP1 splicing and IRE1α phosphorylation (p-IRE1α, active IRE1α) were elevated 36.4-fold and 4.9-fold, respectively, in primary mouse hepatocytes. Of note, with EFV treatment, 47.2% of mouse hepatocytes were apoptotic; which was decreased to 23.9% in the presence of STF 083010, an inhibitor of XBP1 splicing. Experiments performed using pregnane X receptor (PXR)-null mouse hepatocytes revealed that EFV-mediated XBP1 splicing and hepatocyte death were not dependent on PXR, which is a nuclear receptor transcription factor that plays a crucial role in the cellular response to xenobiotics. Interestingly, incubation with the primary metabolite of EFV, 8-hydroxyefavirenz (8-OHEFV), only resulted in 10.3- and 2.9-fold increased XBP1 splicing in human and mouse hepatocytes and no change in levels of p-IRE1α in mouse hepatocytes. To further probe the structure-activity relationship of IRE1α-XBP1 activation by EFV, 16 EFV analogs were employed. Of these, an analog in which the EFV alkyne is replaced with an alkene and an analog in which the oxazinone oxygen is replaced by a carbon stimulated XBP1 splicing in human, mouse, and macaque hepatocytes. These data demonstrate that EFV and compounds sharing the EFV scaffold can activate IRE1α-XBP1 across human, mouse, and macaque species.

Tournefolic acid B, derived from Clinopodium chinense (Benth.) Kuntze, protects against myocardial ischemia/reperfusion injury by inhibiting endoplasmic reticulum stress-regulated apoptosis via PI3K/AKT pathways

BACKGROUND

Protection the heart from ischemia/reperfusion (I/R) injury is an area of intense research, as myocardial infarction is a major cause of mortality and morbidity all around the world. Tournefolic acid B (TAB) is a relative new compound derived from Clinopodium chinense (Benth.) Kuntze (Chinese name: Feng Lun Cai). This traditional Chinese herbal medicine has been used for its activities on anti-inflammatory, lowering blood glucose, antitumor and antiradiation. However, the pharmacological effects of TAB were rarely studied.

PURPOSE

Pathways involving phosphoinositide 3-kinase (PI3K) and protein kinase b (Akt) are crucial in regulating the ER stress and associated apoptosis in the process of I/R injury. In the present study, we aim to investigate the cardioprotective effects of tournefolic acid B (TAB) against myocardial I/R injury and explore the molecular mechanisms involved.

STUDY DESIGN

H9c2 cadiomyocyte were incubated with TAB for 24 h and then exposed to hypoxia/reoxygenation. Isolated rat hearts were subjected to global ischemia and reperfusion in the absence or presence of TAB.

METHODS

The possible mechanisms were investigated in vitro and ex vivo by multiple detection methods including JC-1 staining, ROS detection, activities of caspases detection, TUNEL staining, and Western-blot analysis.

RESULTS

We found that TAB significantly improved the hemodynamic parameters (LVeDP, LVSP, + dP/dt_max, - dP/dt_min, and HR) of isolated rat hearts, and depressed the cardiomyocyte apoptosis. Besides, TAB inhibited the oxidative stress by adjusting the activities of antioxidant enzymes (SOD, CAT, and GSH-Px). The I/R injury triggered the endoplasmic reticulum (ER) stress by activating the ER proteins, such as Grp78, ATF6, PERK, and eIf2α. which are all refrained by TAB. TAB also enhanced the phosphorylation of PI3K and AKT, inhibited the expression of CHOP and Caspase-12, reduced the phosphorylation of JNK, and increased Bcl-2/Bax ratio.

CONCLUSION

TAB protects against myocardial I/R injury by suppressing PI3K/AKT-mediated ER stress, oxidative stress, and apoptosis, revealing a promising therapeutic agent against ischemic cardiovascular diseases.

The Pathogenesis of Diabetes Mellitus by Oxidative Stress and Inflammation: Its Inhibition by Berberine

A substantial knowledge on the pathogenesis of diabetes mellitus (DM) by oxidative stress and inflammation is available. Berberine is a biologically active botanical that can combat oxidative stress and inflammation and thus ameliorate DM, especially type 2 DM. This article describes the potential of berberine against oxidative stress and inflammation with special emphasis on its mechanistic aspects. In diabetic animal studies, the modified levels of proinflammatory cytokines and oxidative stress markers were observed after administering berberine. In renal, fat, hepatic, pancreatic and several others tissues, berberine-mediated suppression of oxidative stress and inflammation was noted. Berberine acted against oxidative stress and inflammation through a very complex mechanism consisting of several kinases and signaling pathways involving various factors, including NF-κB (nuclear factor-κB) and AMPK (AMP-activated protein kinases). Moreover, MAPKs (mitogen-activated protein kinases) and Nrf2 (nuclear factor erythroid-2 related factor 2) also have mechanistic involvement in oxidative stress and inflammation. In spite of above advancements, the mechanistic aspects of the inhibitory role of berberine against oxidative stress and inflammation in diabetes mellitus still necessitate additional molecular studies. These studies will be useful to examine the new prospects of natural moieties against DM.

CHOP/caspase-3 signal pathway involves in mitigative effect of selenium on lead-induced apoptosis via endoplasmic reticulum pathway in chicken testes

Lead (Pb) is an environmental pollutant. Selenium (Se) has alleviative effect on Pb poisoning. However, mitigative effect of Se on Pb-induced apoptosis has not been unclear via endoplasmic reticulum (ER) pathway in chicken testes. The aim of this study was to investigate mitigative effect of Se on apoptosis induced by Pb poisoning via ER pathway in chicken testes. Sixty male chickens (7-day-old) were randomly divided into the control group offered drinking water (DW) and basic diet (BD) (0.49 mg/kg Se), the Se group offered DW and BD containing Na₂SeO₃ (SeBD) (1.00 mg/kg Se), the Pb group offered DW containing (CH₃OO)₂Pb (PbDW) (350.00 mg/L Pb) and BD, and the Pb + Se group offered PbDW and SeBD; and were fed for 90 days. The following contents were performed as follows: histology; antioxidant indexes (reduced glutathione (GSH), malondialdehyde (MDA), glutathione peroxidase (GPx), glutathione S-transferase (GST), and superoxide dismutase (SOD)); mRNA expressions of ER-related genes (glucose-related protein 78 (GRP78), protein kinase-like ER kinase (PERK), eukaryotic initiation factor 2α (eIF2α), activating transcription factor 4 (ATF4), and enhancer-binding protein homologous protein (CHOP)); and apoptosis-related genes (cysteine-aspartic protease (caspase)-3 and caspase-12) in chicken testes. The results indicated that Pb poisoning caused histological changes; increased MDA content; decreased the content of GSH and the activities of GPx, GST, and SOD; and upregulated mRNA expressions of the above five ER-related genes and two apoptosis-related genes in the chicken testes. Se alleviated Pb-induced oxidative stress, ER stress, and apoptosis via CHOP/caspase-3 signal pathway in the chicken testes.

Trehalose activates autophagy and decreases proteasome inhibitor-induced endoplasmic reticulum stress and oxidative stress-mediated cytotoxicity in hepatocytes

AIM

Endoplasmic reticulum stress is associated with the pathophysiology of various liver diseases. Endoplasmic reticulum stress mediates the accumulation of abnormal proteins and leads to oxidative stress, cytoplasmic inclusion body formation, and apoptosis in hepatocytes. Autophagy is a bulk degradation pathway for long-lived cytoplasmic proteins or damaged organelles and is also a major degradation pathway for many aggregate-prone and disease-causing proteins. We previously reported that rapamycin, a mammalian target of rapamycin inhibitor, activated autophagy and decreased proteasome inhibitor-mediated ubiquitinated protein accumulation, cytoplasmic inclusion body formation, and apoptosis in hepatocytes. Trehalose is a non-reducing disaccharide that has been shown to activate autophagy. It has been reported to decrease aggregate-prone proteins and ameliorate cytotoxicity in neurodegenerative disease models. However, the effects of trehalose in hepatocytes are unclear.

METHODS

We show here that trehalose activated autophagy and reduced endoplasmic reticulum stress, cytoplasmic inclusion body formation, and apoptosis in proteasome inhibitor-treated liver-derived cultured cells.

CONCLUSION

To our knowledge, this is the first report showing that trehalose activates autophagy and has cytoprotective effects in hepatocytes. Our findings suggest that trehalose can become a therapeutic agent for endoplasmic reticulum stress-related liver diseases.

Endoplasmic Reticulum Stress PERK-ATF4-CHOP Pathway Is Associated with Hypothalamic Neuronal Injury in Different Durations of Stress in Rats

The hypothalamus, which is the initial part of the hypothalamic-pituitary-adrenal (HPA) axis, plays a critical role in regulating stress in the central nervous system. The present study aimed to determine whether endoplasmic reticulum stress in hypothalamic neurons is differentially stimulated by varying durations of stress exposure, which ultimately leads to pathological changes in neurons by affecting HPA axis function. There is a need for better morphological evidence of the mechanisms involved in stress-induced neuron injury. A stress model was established in rats by restraining for 8 h and forced ice-water swimming for 5 min each day. The stress-inducing process lasted for 1, 3, 7, 14, and 21 days. Enzyme-linked immunosorbent assay (ELISA) was used to assay serum glucocorticoid levels. Thionine staining was used to observe morphological changes in hypothalamic neurons. Immunohistochemistry and microscopy-based multicolor tissue cytometry (MMTC) was used to detect changes in expression of endoplasmic reticulum stress protein GRP78, ATF4, and CHOP. Serum glucocorticoid levels significantly increased after 3 days of stress exposure and the levels peaked by 7 days. By 21 days, however, the levels were significantly decreased. Thionine staining revealed that prolonged stress exposure resulted in hypothalamic neurons with edema, a lack of Nissl bodies, and pyknotic neurons. Immunohistochemistry and MMTC showed that increasing stress periods significantly decreased GRP78 expression, although ATF4 and CHOP protein expression significantly increased. Stress resulted in pathological changes and significant dynamic changes because of endoplasmic reticulum stress in rat hypothalamic neurons. These results suggested that the endoplasmic reticulum stress PERK-ATF4-CHOP pathway may be associated with hypothalamic neuronal injury.

Chemical Chaperone 4-Phenylbutyric Acid Reduces Cardiac Ischemia/Reperfusion Injury by Alleviating Endoplasmic Reticulum Stress and Oxidative Stress

Background

Cardiovascular diseases are the leading cause of death in many countries and myocardial ischemia-reperfusion (I/R) injury is the cause of many serious heart diseases. Recent reports suggested that endoplasmic reticulum (ER) stress is associated with the progress of ischemia/reperfusion (I/R) injury. In a previous study, we illustrated that 4-phenylbutyric acid (4-PBA) reduces I/R-induced cell death in vitro through inhibiting the ER stress-initiated cell apoptosis. In the present study we investigated whether 4-PBA improves heart function in isolated rat hearts subjected to I/R and elucidated the potential mechanisms involved in 4-PBA-induced cardioprotective effects.

Material/Methods

The isolated rat hearts were subjected to global ischemia and reperfusion in the absence or presence of 4-PBA. Hemodynamic parameters (LVSP, LVEDP, ±dP/dt_max, and HR) were monitored and histopathological examination was applied. The biomarkers related to oxidative stress were detected by LDH, ROS, MDA, CK, SOD, and GSH-Px kits. A TUNEL apoptosis assay kit was used to detect apoptosis. The expression levels of ER stress and apoptosis proteins were evaluated by Western blotting.

Results

We found that 4-PBA (5 mM, 10 mM) pretreatment significantly attenuated cardiac dysfunction and depressed oxidative stress induced by I/R. Moreover, I/R activated the ER stress proteins Grp78 and PERK, which are all decreased by 4-PBA. 4-PBA pretreatment also inhibited the expression of CHOP, Caspase-12, and Bax, reduced the phosphorylation of JNK, and enhanced the expression of anti-apoptotic protein Bcl-2.

Conclusions

We elucidated the significant protective effects of 4-PBA against I/R injuries by inhibition of ER stress, oxidative stress, and their associated apoptosis.

Regulation of ER stress-induced autophagy by GSK3β-TIP60-ULK1 pathway

Endoplasmic reticulum (ER) stress is involved in many cellular processes. Emerging evidence suggests that ER stress can trigger autophagy; however, the mechanisms by which ER stress regulates autophagy and its role in this condition are not fully understood. HIV Tat-interactive protein, 60 kDa (TIP60) is a newly discovered acetyltransferase that can modulate autophagy flux by activating ULK1 upon growth factor deprivation. In this study, we investigated the mechanisms by which ER stress induces autophagy. We showed that ER stress activates glycogen synthase kinase-3β (GSK3β). This led to a GSK3β-dependent phosphorylation of TIP60, triggering a TIP60-mediated acetylation of ULK1 and activation of autophagy. Inhibition of either GSK3β or TIP60 acetylation activities significantly attenuated ER stress-induced autophagy. Moreover, enhancing the level of TIP60 attenuated the level of CHOP after ER stress, and reduced the ER stress-induced cell death. In contrast, expression of TIP60 mutant that could not be phosphorylated by GSK3β exacerbated the generation of CHOP and increased the ER stress-induced cell death. These findings reveal that ER stress engages the GSK3β-TIP60-ULK1 pathway to increase autophagy. Attenuation of this pathway renders cells more sensitive to and increases the toxicity of ER stress.

Cytoskeletal reorganization and cell death in mitoxantrone-treated lung cancer cells

The aim of this study was to investigate the cytotoxic effect of mitoxantrone on two human non-small cell lung cancer cell lines, A549 (p53+) and H1299 (p53-). To our knowledge, this is the first study to evaluate the impact of MXT on the organization of cytoskeletal proteins. Analyses were performed using fluorescence and transmission electron microscopy, spectrophotometric techniques, flow cytometry and Western blotting. It was shown that H1299 cells are significantly more sensitive to mitoxantrone than the A549 cell line, and that the growth-inhibitory effect of the drug is dose-dependent only after longer incubation. The observed presence of ring-like microtubule structures and mitochondria surrounding the nuclei of H1299 cells could be a manifestation of increased tubulin polymerization requiring large amounts of energy, whereas the loss of actin stress fibers was presumably not the cause but rather the consequence of cell death induction. Treatment with mitoxantrone also led to the appearance of structures resembling agresomes in H1299 cells and to nucleolar segregation in both cell lines. It was demonstrated that cells arrested in the S phase were most susceptible to cell death induction, and that triggered intracellular changes led mainly to apoptosis. High concentrations induced necrosis and some H1299 cells exhibited morphological features of mitotic catastrophe.

Copper induces hepatocyte injury due to the endoplasmic reticulum stress in cultured cells and patients with Wilson disease

Copper is an essential trace element, however, excess copper is harmful to human health. Excess copper-derived oxidants contribute to the progression of Wilson disease, and oxidative stress induces accumulation of abnormal proteins. It is known that the endoplasmic reticulum (ER) plays an important role in proper protein folding, and that accumulation of misfolded proteins disturbs ER homeostasis resulting in ER stress. However, copper-induced ER homeostasis disturbance has not been fully clarified. We treated human hepatoma cell line (Huh7) and immortalized-human hepatocyte cell line (OUMS29) with copper and chemical chaperones, including 4-phenylbutyrate and ursodeoxycholic acid. We examined copper-induced oxidative stress, ER stress and apoptosis by immunofluorescence microscopy and immunoblot analyses. Furthermore, we examined the effects of copper on carcinogenesis. Excess copper induced not only oxidative stress but also ER stress. Furthermore, excess copper induced DNA damage and reduced cell proliferation. Chemical chaperones reduced this copper-induced hepatotoxicity. Excess copper induced hepatotoxicity via ER stress. We also confirmed the abnormality of ultra-structure of the ER of hepatocytes in patients with Wilson disease. These findings show that ER stress plays a pivotal role in Wilson disease, and suggests that chemical chaperones may have beneficial effects in the treatment of Wilson disease.

Lipid-Induced Endoplasmic Reticulum Stress Impairs Selective Autophagy at the Step of Autophagosome-Lysosome Fusion in Hepatocytes

Blockage of hepatic autophagic degradation system occurs in obesity and is associated with the development of nonalcoholic fatty liver disease. However, the mechanism of this blockage remains unclear. We found a high-fat diet induced accumulation of autophagosomes in the mice livers. However, autophagy substrates such as p62 and ubiquitinated proteins also accumulated in the livers in this model. These findings indicate the possibility that a high-fat diet impairs autophagic flux in the liver. Then, to assess the autophagic flux in more detail, we performed analyses of autophagic flux in cultured hepatocytes exposed to monounsaturated fatty acids (FAs) or saturated FAs (SFAs). SFAs but not monounsaturated FAs suppressed degradation of contents in the autophagosomes. We analyzed each stage of the autophagy pathway (ie, autophagosome formation, autophagosome-lysosome fusion, lysosomal degradation) in cultured hepatocytes treated with monounsaturated FAs or SFAs and found that SFAs impaired autophagosome-lysosome fusion. This impairment occurred in an endoplasmic reticulum stress-dependent manner. Moreover, ubiquitin and p62-positive inclusions observed in high-fat diet-fed mice livers and SFA-treated cells were sequestered within autophagosomes. We also found that SFA-induced accumulation of Ser351-phosphorylated p62, which is indispensable for selective autophagy, further increased on administration of a lysosomal proteinase inhibitor. Although lipid-induced endoplasmic reticulum stress interferes with the autophagosome-lysosome fusion, selective autophagic sequestration of aggregated proteins is not inhibited.

Trace Mineral Overload Induced Hepatic Oxidative Damage and Apoptosis in Pigs with Long-Term High-Level Dietary Mineral Exposure

The present study investigated the effects of dietary trace mineral (Cu, Fe, Mn, and Zn) supplemental strategies on liver oxidative stress, endoplasmic reticulum stress, inflammation, and apoptosis of pigs. A total of 96 Duroc × Landrace × Yorkshire (DLY) piglets were randomly divided into four groups: considered or not considered the trace mineral concentrations in basal diet, and then added to the requirements proposed by NRC (2012) (+B/NR or -B/NR); and considered or not considered the basal diet's trace mineral concentrations and then added to the level of commercial trace mineral supplement (+B/PL or -B/PL). Pigs were fed from 6.5 to 115 kg. Compared with +B/NR diets, -B/PL diets increased serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) concentrations (P < 0.05), resulted in high levels of Fe, Cu, Mn, and Zn accumulation in liver (P < 0.05), as well as led to hepatic oxidative damage with the high concentrations of thiobarbituric acid reactive substance (TBARS), protein carbonylation (PCO), and 8-hydroxyguanine (8-OHG) in liver (P < 0.05). Furthermore, pigs fed -B/PL diets increased CCAAT/enhancer-binding protein homologous protein (CHOP), eukaryotic initiation factor-2α (eIF-2a), interleukin-6(IL-6), B-cell lymphoma leukemia-2-associated X protein (Bax), and caspase-3, caspase-8, and caspase-9 gene expression (P < 0.05) in liver. -B/PL diets also up-regulated hepatic mRNA expression of phosphoenolpyruvate carboxykinase1 (PEPCK1), glucose-6-phosphatase (G6PC), acetyl-CoA carboxylase (ACC), fatty acid synthase (FAS) (P < 0.05) and down-regulated hormone-sensitive lipase (HSL) mRNA expression (P < 0.05) when compared with those of the + B/NR diet group. Taken together, the results indicated that long-term dietary mineral exposure with the commercial supplement level could cause harm to the structure and metabolic function of liver in pigs.

Cardioprotective effects of Notoginsenoside R1 against ischemia/reperfusion injuries by regulating oxidative stress- and endoplasmic reticulum stress- related signaling pathways

Background: Recent reports suggested the involvement of oxidative stress- and endoplasmic reticulum stress (ERS)-associated pathways in the progression of ischemia/reperfusion (I/R) injury. Notoginsenoside R1 (NGR1) is a novel saponin isolated from P. notoginseng, which has a history of prevention and treatment of cardiovascular diseases. Objective: We aimed to examine the cardioprotective effects of NGR1 on I/R-induced heart dysfunction ex vivo and in vitro. Methods: H9c2 cadiomyocytes were incubated with NGR1 for 24 h and exposed to hypoxia/reoxygenation. Isolated rat hearts were perfused by NGR1 for 15 min and then subjected to global ischemia/reperfusion. Hemodynamic parameters were monitored as left ventricular systolic pressure (LVSP), heart rate, and maximal rate of increase and decrease of left ventricular pressure (±dP/dt max/min). Results: NGR1 pretreatment prevents cell apoptosis and delays the onset of ERS by decreasing the protein expression levels of ERS-responsive proteins GRP78, P-PERK, ATF6, IRE, and inhibiting the expression of pro-apoptosis proteins CHOP, Caspase-12, and P-JNK. Besides, NGR1 scavenges free radical, and increases the activity of antioxidase. NGR1 inhibits Tunicamycin-induced cell death and cardic dysfunction. Conclusion: We elucidated the significant cardioprotective effects of NGR1 against I/R injuries, and demonstrated the involvement of oxidative stress and ERS in the protective effects of NGR1.

Characterization of swine testicular cell line as immature porcine Sertoli cell line

Swine testicular (ST) cell line is isolated from swine fetal testes and has been widely used in biomedical research fields related to pig virus infection. However, the potential benefit and utilization of ST cells in boar reproductive studies has not been fully explored. As swine fetal testes mainly contain multiple types of cells such as Leydig cells, Sertoli cells, gonocytes, and peritubular myoid cells, it is necessary to clarify the cell type of ST cell line. In this study, we identified ST cell line was a collection of Sertoli cells by analyzing the unique morphological characteristic with satellite karyosomes and determining the protein expression of two markers (androgen-binding protein, ABP; Fas ligand, FASL) of Sertoli cells. Then ST cells were further confirmed to be immature Sertoli cells by examining the expression of three markers (anti-Mullerian hormone, AMH; keratin 18, KRT18; follicle-stimulating hormone receptor, FSHR). In conclusion, ST cells are a collection of immature Sertoli cells which can be good experimental materials for the researches involved in Sertoli cell functions and maturation, or even in boar reproductions.

Trinitrotoluene Induces Endoplasmic Reticulum Stress and Apoptosis in HePG2 Cells

Background

This study aims to describe trinitrotoluene (TNT)-induced endoplasmic reticulum stress (ERS) and apoptosis in HePG2 cells.

Material/Methods

HePG2 cells were cultured in vitro with 0, 6, 12, or 24 μg/ml TNT solution for 12, 24, and 48 h. Western blotting was performed to detect intracellular ERS-related proteins, including glucose-regulated protein (GRP) 78, GRP94, Caspase 4, p-Jun N-terminal kinase (JNK), and C/EBP homologous protein (CHOP). Real-time PCR was used to measure mRNA expression from the respective genes.

Results

The expressions of ERS-related proteins GRP78 and GRP94 as well as mRNA and protein expression of ERS signaling apoptotic CHOP in the TNT treatment group were significantly increased. In addition, the mRNA and protein expression levels of ERS-induced apoptotic protein Caspase-4 were significantly increased. Flow cytometry revealed that after TNT treatment, the apoptosis rate also significantly increased.

Conclusions

TNT could increase the expression levels of GRP78, GRP94, Caspase-4, and CHOP in HePG2 cells; this increase in protein expression might be involved in HePG2 apoptosis through the induction of the ERS pathway.

Phenylbutyric acid inhibits epithelial-mesenchymal transition during bleomycin-induced lung fibrosis

A recent report showed that unfolded protein response (UPR) signaling was activated during bleomycin (BLM)-induced pulmonary fibrosis. Phenylbutyric acid (PBA) is an endoplasmic reticulum (ER) chemical chaperone that inhibits the UPR signaling. The present study investigated the effects of PBA on BLM-induced epithelial-mesenchymal transition (EMT) and pulmonary fibrosis. For induction of pulmonary fibrosis, all mice except controls were intratracheally injected with a single dose of BLM (3.0mg/kg). In PBA+BLM group, mice were intraperitoneally injected with PBA (150mg/kg) daily. Three weeks after BLM injection, EMT was measured and pulmonary fibrosis was evaluated. BLM-induced pulmonary UPR activation was inhibited by PBA. Moreover, BLM-induced pulmonary nuclear factor kappa B (NF-κB) p65 activation was blocked by PBA. In addition, BLM-induced up-regulation of pulmonary inflammatory cytokines was repressed by PBA. Further analysis showed that BLM-induced α-smooth muscle actin (α-SMA), a marker for EMT, was significantly attenuated by PBA. Moreover, BLM-induced pulmonary collagen (Col1α1 and Col1α2) was obviously inhibited by PBA. Importantly, BLM-induced pulmonary fibrosis, as determined using Sirius red staining, was obviously alleviated by PBA. Taken together, these results suggest that PBA alleviates ER stress-mediated EMT in the pathogenesis of BLM-induced pulmonary fibrosis.

Evidence of endoplasmic reticulum stress and liver inflammation in the American mink Neovison vison with benign hepatic steatosis

We investigated the presence of inflammatory signs in the progression of fatty liver disease induced by fasting. Sixty standard black American mink (Neovison vison) were fasted for 0, 1, 3, 5, or 7 days and one group for 7 days followed by re-feeding for 28 days. Liver sections were evaluated histologically and liver mRNA levels indicating endoplasmic reticulum (ER) stress, adipogenic transformation, and inflammation were assessed by quantitative real-time PCR. After 3 days of fasting, the mink had developed moderate liver steatosis. Increased hyaluronan reactivity in lymphocytic foci but no Mallory-Denk bodies were seen in livers of the mink fasted for 5-7 days. Up-regulation of glucose-regulated protein, 78 kDa was observed on day 7 indicating ER stress, especially in the females. Liver lipoprotein lipase and monocyte chemoattractant protein 1 mRNA levels increased in response to 5-7 days of food deprivation, while tumor necrosis factor α (TNF-α) was the highest in the mink fasted for 5 days. The expression of the genes of interest, except for TNF-α, correlated with each other and with the liver fat content. The mRNA levels were found to change more rapidly below n-3/n-6 polyunsaturated fatty acid ratio threshold of 0.15. Following re-feeding, hepatocyte morphology and mRNA abundance returned to pre-fasting levels. Within the studied timeframe, evidence for ER stress, adipogenic transformation, and liver inflammation suggested incipient transition from steatosis to steatohepatitis with potential for development of more severe liver disease. This may present a possibility to influence disease progression before histologically observable steatohepatitis.

Trans-10, cis-12 conjugated linoleic acid reduces neutral lipid content and may affect cryotolerance of in vitro-produced crossbred bovine embryos

Background

Due to high neutral lipids accumulation in the cytoplasm, in vitro-produced embryos from Bos primigenius indicus and their crosses are more sensitive to chilling and cryopreservation than those from Bos primigenius taurus. The objective of the present study was to evaluate the effects of trans-10, cis-12 conjugated linoleic acid (CLA) on the development and cryotolerance of crossbred Bos primigenius taurus x Bos primigenius indicus embryos produced in vitro, and cultured in the presence of fetal calf serum. Bovine zygotes (n = 1,692) were randomly assigned to one of the following treatment groups: 1) Control, zygotes cultured in Charles Rosenkrans 2 amino acid (CR2aa) medium (n = 815) or 2) CLA, zygotes cultured in CR2aa medium supplemented with 100 μmol/L of trans-10, cis-12 CLA (n = 877). Embryo development (cleavage and blastocyst rates evaluated at days 3 and 8 of culture, respectively), lipid content at morula stage (day 5) and blastocyst cryotolerance (re-expansion and hatching rates, evaluated 24 and 72 h post-thawing, respectively) were compared between groups. Additionally, selected mRNA transcripts were measured by Real–Time PCR in blastocyst stage.

Results

The CLA treatment had no effect on cleavage and blastocyst rates, or on mRNA levels for genes related to cellular stress and apoptosis. On the other hand, abundance of mRNA for the 1-acylglycerol-3-phosphate 0-acyltransferase-encoding gene (AGPAT), which is involved in triglycerides synthesis, and consequently neutral lipid content, were reduced by CLA treatment. A significant increase was observed in the re-expansion rate of embryos cultured with trans-10, cis-12 CLA when compared to control (56.3 vs. 34.4%, respectively, P = 0.002). However, this difference was not observed in the hatching rate (16.5 vs. 14.0%, respectively, P = 0.62).

Conclusions

The supplementation with trans-10, cis-12 CLA isomer in culture medium reduced the lipid content of in vitro produced bovine embryos by reducing the gene expression of 1-acylglycerol 3-phosphate 0-acyltransferase (AGPAT) enzyme. However, a possible improvement in embryo cryotolerance in response to CLA, as suggested by increased blastocyst re-expansion rate, was not confirmed by hatching rates.

ω-Hydroxyundec-9-enoic acid induces apoptosis through ROS-mediated endoplasmic reticulum stress in non-small cell lung cancer cells

ω-Hydroxyundec-9-enoic acid (ω-HUA), a hydroxyl unsaturated fatty acid derivative, is involved in the antifungal activity of wild rice (Oryza officinalis). Here, we investigated the anti-cancer activity of ω-HUA on a non-small cell lung cancer (NSCLC) cell line. ω-HUA increased apoptosis and induced cleavages of caspase-6, caspase-9, and poly (ADP-ribose) polymerase (PARP). ω-HUA treatment significantly induced endoplasmic reticulum (ER) stress response. Suppression of CHOP expression and inhibiting ER stress by 4-phenylbutyrate (4-PBA) significantly attenuated the ω-HUA treatment-induced activation of caspase-6, caspase-9, and PARP, and subsequent apoptotic cell death, indicating a role for ER stress in ω-HUA-induced apoptosis. In addition, cells subjected to ω-HUA exhibited significantly increased quantity of reactive oxygen species (ROS), and the ROS scavenger N-acetyl-L-cysteine (NAC) inhibited ω-HUA-induced apoptotic cell death and ER stress signals, indicating a role for ROS in ER stress-mediated apoptosis in ω-HUA-treated cells. Taken together, these results suggest that sequential ROS generation and ER stress activation are critical in ω-HUA treatment-induced apoptosis and that ω-HUA represents a promising candidate for NSCLC treatment.

Yiqi Huoxue Recipe Improves Heart Function through Inhibiting Apoptosis Related to Endoplasmic Reticulum Stress in Myocardial Infarction Model of Rats

Objective. To explore the mechanism of cardioprotective effects of Chinese medicine, Yiqi Huoxue recipe, in rats with myocardial infarction- (MI-) induced heart failure. Methods. Male Sprague-Dawley rats underwent left anterior descending artery (LAD) ligation or sham operation. The surviving MI rats were divided randomly into three groups: MI (5 mL/kg/d NS by gavage), MI + Metoprolol Tartrate (MT) (12 mg/kg/d MT by gavage), and MI + Yiqi Huoxue (5 mL/kg recipe by gavage). And the sham operation rats were given 5 mL/kg/d normal saline. Treatments were given on the day following surgery for 4 weeks. Then rats were detected for heart structure and function by transthoracic echocardiography. Apoptosis in heart tissues was detected by TUNEL staining. To determine whether the endoplasmic reticulum (ER) stress response pathway is included in the cardioprotective function of the recipe, ER stress related proteins such as GRP78 and caspase-12 were examined. Results. Yiqi Huoxue recipe attenuated heart function injury, reversed histopathological damage, alleviated myocardial apoptosis and inhibited ER stress in MI rats. Conclusion. All the results suggest that Yiqi Huoxue recipe improves the injured heart function maybe through inhibition of ER stress response pathway, which is a promising target in therapy for heart failure.

Antioxidant and anti-inflammatory activities of berberine in the treatment of diabetes mellitus

Oxidative stress and inflammation are proved to be critical for the pathogenesis of diabetes mellitus. Berberine (BBR) is a natural compound isolated from plants such as Coptis chinensis and Hydrastis canadensis and with multiple pharmacological activities. Recent studies showed that BBR had antioxidant and anti-inflammatory activities, which contributed in part to its efficacy against diabetes mellitus. In this review, we summarized the antioxidant and anti-inflammatory activities of BBR as well as their molecular basis. The antioxidant and anti-inflammatory activities of BBR were noted with changes in oxidative stress markers, antioxidant enzymes, and proinflammatory cytokines after BBR administration in diabetic animals. BBR inhibited oxidative stress and inflammation in a variety of tissues including liver, adipose tissue, kidney and pancreas. Mechanisms of the antioxidant and anti-inflammatory activities of BBR were complex, which involved multiple cellular kinases and signaling pathways, such as AMP-activated protein kinase (AMPK), mitogen-activated protein kinases (MAPKs), nuclear factor erythroid-2-related factor-2 (Nrf2) pathway, and nuclear factor- κ B (NF- κ B) pathway. Detailed mechanisms and pathways for the antioxidant and anti-inflammatory activities of BBR still need further investigation. Clarification of these issues could help to understand the pharmacology of BBR in the treatment of diabetes mellitus and promote the development of antidiabetic natural products.

Alpha-chlorofatty acid accumulates in activated monocytes and causes apoptosis through reactive oxygen species production and endoplasmic reticulum stress

OBJECTIVE

Myeloperoxidase-enriched monocytes play important roles in inflammatory disease, such as atherosclerosis. We previously demonstrated that α-chlorofatty aldehydes are produced as a result of plasmalogen targeting by myeloperoxidase-derived hypochlorous acid in activated monocytes. Here, we show α-chlorofatty acid (α-ClFA), a stable metabolite of α-chlorofatty aldehydes, accumulates in activated monocytes and mediates the molecular effects of α-ClFA on monocytes/macrophages.

APPROACH AND RESULTS

Liquid chromatography-mass spectrometry revealed that α-ClFA is elevated 5-fold in phorbol myristate-stimulated human monocytes rising to ≈20 μmol/L when compared with unstimulated cells. Using human THP-1 monocytes and RAW 264.7 cells as in vitro models, we tested the hypothesis that α-ClFA is a cell death mediator that could potentially participate in pathophysiological roles of monocytes in diseases, such as atherosclerosis. Indeed, 2-chlorohexadecanoic acid, the 16-carbon molecular species of α-ClFA, caused significant apoptosis of primary monocytes. Similarly, 2-chlorohexadecanoic acid also caused apoptosis in THP-1 human monocytes and RAW 264.7 mouse macrophages as determined by annexin V-propidium iodide staining and terminal deoxynucleotidyl transferase dUTP nick end labeling staining, respectively. 2-Chlorohexadecanoic acid treatment also increased caspase-3 activity and poly (ADP-ribose) polymerase cleavage in THP-1 cells. 2-Chlorohexadecanoic acid likely elicits apoptosis by increasing both reactive oxygen species production and endoplasmic reticulum stress because antioxidants and CCAAT/enhancer-binding protein homologous protein block such induced cell apoptosis.

CONCLUSIONS

The stable chlorinated lipid, α-ClFA, accumulates in activated primary human monocytes and elicits monocyte apoptosis through increased reactive oxygen species production and endoplasmic reticulum stress, providing a new insight into chlorinated lipids and monocytes in inflammatory disease.

Superoxide dismutase 1 overexpression in mice abolishes maternal diabetes-induced endoplasmic reticulum stress in diabetic embryopathy

OBJECTIVE

Both oxidative stress and endoplasmic reticulum stress (ER stress) are causal events in diabetic embryopathy. We tested whether oxidative stress causes ER stress.

STUDY DESIGN

Wild-type (WT) and superoxide dismutase 1 (SOD1)-overexpressing day 8.75 embryos from nondiabetic WT control with SOD1 transgenic male and diabetic WT female with SOD1 transgenic male were analyzed for ER stress markers: C/EBP-homologous protein (CHOP), calnexin, eukaryotic initiation factor 2α (eIF2α), protein kinase ribonucleic acid (RNA)-like ER kinase (PERK), binding immunoglobulin protein, protein disulfide isomerase family A member 3, kinases inositol-requiring protein-1α (IRE1α), and the X-box binding protein (XBP1) messenger RNA (mRNA) splicing.

RESULTS

Maternal diabetes significantly increased the levels of CHOP, calnexin, phosphorylated (p)-eIF2α, p-PERK, and p-IRE1α; triggered XBP1 mRNA splicing; and enhanced ER chaperone gene expression in WT embryos. SOD1 overexpression blocked these diabetes-induced ER stress markers.

CONCLUSION

Mitigating oxidative stress via SOD1 overexpression blocks maternal diabetes-induced ER stress in vivo.

Endoplasmic reticulum stress in nonalcoholic fatty liver disease

The underlying causes of nonalcoholic fatty liver disease are unclear, although recent evidence has implicated the endoplasmic reticulum in both the development of steatosis and progression to nonalcoholic steatohepatitis. Disruption of endoplasmic reticulum homeostasis, often termed ER stress, has been observed in liver and adipose tissue of humans with nonalcoholic fatty liver disease and/or obesity. Importantly, the signaling pathway activated by disruption of endoplasmic reticulum homeostasis, the unfolded protein response, has been linked to lipid and membrane biosynthesis, insulin action, inflammation, and apoptosis. Therefore, understanding the mechanisms that disrupt endoplasmic reticulum homeostasis in nonalcoholic fatty liver disease and the role of the unfolded protein response in the broader context of chronic, metabolic diseases have become topics of intense investigation. The present review examines the endoplasmic reticulum and the unfolded protein response in the context of nonalcoholic fatty liver disease.

Purple sweet potato color attenuates hepatic insulin resistance via blocking oxidative stress and endoplasmic reticulum stress in high-fat-diet-treated mice

Purple sweet potato color (PSPC), a class of naturally occurring anthocyanins, has been reported to possess a variety of health-promoting properties. Emerging evidence indicates that PSPC can suppress postprandial hyperglycemia via inhibition of α-glucosidases. However, the protective effects of PSPC on hepatic insulin resistance and the precise mechanisms underlying these protective effects have never been investigated. In this study, our data showed that PSPC effectively improved the fasting blood glucose level, glucose and insulin tolerance by suppressing reactive oxygen species (ROS) production and by restoring glutathione (GSH) content and antioxidant enzymes' activities. PSPC further prevented the oxidative-stress-mediated endoplasmic reticulum (ER) stress in the livers of high-fat-diet (HFD)-treated mice. Moreover, PSPC dramatically suppressed the c-Jun-N-terminal kinase 1 and I kappa B kinase β activation and nuclear factor-kappa B p65 nuclear translocation caused by oxidative and ER stress in the livers of HFD-treated mice. Ultimately, PSPC notably restored the impairment of the insulin receptor substrate-1/phosphoinositide 3 kinase/protein kinase B (Akt) insulin signaling in the livers of HFD-treated mice. In conclusion, our findings indicate that PSPC protected against HFD-induced hepatic insulin resistance via decreasing ROS level and blocking ROS-mediated ER stress.

Aging modulates susceptibility to mouse liver Mallory-Denk body formation

Mallory-Denk bodies (MDBs) are hepatocyte cytoplasmic inclusions found in several liver diseases and consist primarily of the cytoskeletal proteins, keratins 8 and 18 (K8/K18). Recent evidence indicates that the extent of stress-induced protein misfolding, a K8>K18 overexpression state, and transglutaminase-2 activation promote MDB formation. In addition, the genetic background and gender play an important role in mouse MDB formation, but the effect of aging on this process is unknown. Given that oxidative stress increases with aging, the authors hypothesized that aging predisposes to MDB formation. They used an established mouse MDB model-namely, feeding non-transgenic male FVB/N mice (1, 3, and 8 months old) with 3,5 diethoxycarbonyl-1,4-dihydrocollidine for 2 months. MDB formation was assessed using immunofluorescence staining and biochemically by demonstrating keratin and ubiquitin-containing crosslinks generated by transglutaminase-2. Immunofluorescence staining showed that old mice had a significant increase in MDB formation compared with young mice. MDB formation paralleled the generation of high molecular weight ubiquitinated keratin-containing complexes and induction of p62. Old mouse livers had increased oxidative stress. In addition, 20S proteasome activity and autophagy were decreased, and endoplasmic reticulum stress was increased in older livers. Therefore, aging predisposes to experimental MDB formation, possibly by decreased activity of protein degradation machinery.

Clinical and experimental applications of sodium phenylbutyrate

Histone acetyltransferase and histone deacetylase are enzymes responsible for histone acetylation and deacetylation, respectively, in which the histones are acetylated and deacetylated on lysine residues in the N-terminal tail and on the surface of the nucleosome core. These processes are considered the most important epigenetic mechanisms for remodeling the chromatin structure and controlling the gene expression. Histone acetylation is associated with gene activation. Sodium phenylbutyrate is a histone deacetylase inhibitor that has been approved for treatement of urea cycle disorders and is under investigation in cancer, hemoglobinopathies, motor neuron diseases, and cystic fibrosis clinical trials. Due to its characteristics, not only of histone deacetylase inhibitor, but also of ammonia sink and chemical chaperone, the interest towards this molecule is growing worldwide. This review aims to update the current literature, involving the use of sodium phenylbutyrate in experimental studies and clinical trials.

Hepatocyte-derived cultured cells with unusual cytoplasmic keratin-rich spheroid bodies

Cytoplasmic inclusions are found in a variety of diseases that are characteristic morphological features of several hepatic, muscular and neurodegenerative disorders. They display a predominantly filamentous ultrastructure that is also observed in malignant rhabdoid tumor (MRT). A cellular clone containing an intracytoplasmic body was isolated from hepatocyte cell culture, and in the present study we examined whether this body might be related or not to Mallory-Denk body (MDB), a well characterized intracytoplasmic inclusion, or whether this cellular clone was constituted by malignant rhabdoid tumor cells. The intracytoplasmic body was observed in electron microscopy (EM), confocal immunofluorescence microscopy and several proteins involved in the formation of its structure were identified. Using light microscopy, a spheroid body (SB) described as a single regular-shaped cytoplasmic body was observed in cells. During cytokinesis, the SB was disassembled and reassembled in a way to reconstitute a unique SB in each progeny cell. EM examination revealed that the SB was not surrounded by a limiting membrane. However, cytoplasmic filaments were concentrated in a whorled array. These proteins were identified as keratins 8 and 18 (K8/K18), which formed the central core of the SB surrounded by a vimentin cage-like structure. This structure was not related to Mallory-Denk body or aggresome since no aggregated proteins were located in SB. Moreover, the structure of SB was not due to mutations in the primary sequence of K8/K18 and vimentin since no difference was observed in the mRNA sequence of their genes, isolated from Huh-7 and Huh-7w7.3 cells. These data suggested that cellular factor(s) could be responsible for the SB formation process. Aggregates of K18 were relocated in the SB when a mutant of K18 inducing disruption of K8/K18 IF network was expressed in the cellular clone. Furthermore, the INI1 protein, a remodeling-chromatin factor deficient in rhabdoid cells, which contain a spheroid perinuclear inclusion body, was found in our cellular clone. In conclusion, our data suggest that Huh-7w7.3 cells constitute an excellent model for determining the cellular factor(s) involved in the process of spheroid perinuclear body formation.

Hyperoxia-induced activation of the integrated stress response in the newborn rat lung

Diverse environmental stresses stimulate eukaryotic translation initiation factor 2α (eIF2α) phosphorylation, leading to a stress-resistant state characterized by global attenuation of protein synthesis and induction of cytoprotective genes. The signal transduction network culminating in these effects is referred to as the integrated stress response (ISR) or, when initiated by misfolded proteins within the endoplasmic reticulum (ER), the unfolded protein response (UPR). Given that we previously reported that exposure of 4-day-old Sprague-Dawley rats to 95% O(2) (Ox) diminishes global pulmonary protein synthesis and increases eIF2α phosphorylation, we conducted the current study to determine whether Ox activates the ISR or UPR. We found that Ox-induced alterations in ER morphology of alveolar type II cells and interstitial fibroblasts were not associated with activation of the UPR sensors PERK or activating transcription factor (ATF) 6 or with X-box binding protein-1 mRNA splicing in whole lung extracts. Exposure to Ox enhanced ATF4 immunoreactivity and nuclear protein content, followed by a 2- and 5-fold increase in ATF3 protein and mRNA expression, respectively. The accumulation of nuclear ATF4 protein coincided with induction of glutamate-cysteine ligase catalytic subunit, an ISR-responsive gene. Immunohistochemistry revealed that changes in ATF3/4 expression were prominent in the alveolus, whereas primary cell culture implicated epithelial and endothelial cells as targets. Finally, induction of ISR intermediates in the intact lung occurred in the absence of the phosphorylation of PKR, JNK, ERK1/2, and p38 MAPK. These findings demonstrate that Ox activates the ISR within the newborn lung and highlight regional and cell-specific alterations in the expression ISR transcription factors that regulate redox balance.

Human bladder smooth muscle cell damage in disturbed oxygen tension

OBJECTIVE

To characterize human bladder smooth muscle cell reactions to disturbed oxygen tension. Clinical studies have shown a close correlation between bladder ischemia and lower urinary tract symptoms in elderly patients.

MATERIALS AND METHODS

Confluent cultured human bladder smooth muscle cells were incubated under normoxia, continuous hypoxia, and oxidative stress (hypoxia/reoxygenation) conditions using a computerized oxycycler system. After 48 hours, cell samples were collected and processed for fluorometric assessment of oxidative injury, enzyme immunoassay of antioxidant capacity, and transmission electron microscopy.

RESULTS

Lipid peroxidation was found in cell hypoxia and oxidative stress, whereas protein oxidation was evident in oxidative stress only. Cell antioxidant capacity decreased in oxidative stress but remained unchanged in hypoxia. Oxidative products were present in cell oxidative stress only, whereas nitrosative products increased in both hypoxia and oxidative stress conditions. Forty-eight hours of hypoxia and oxidative stress had no effect on cell senescence. Thickened deformed cell membrane, swollen mitochondria, and enlarged endoplasmic reticulum (ER) were found in cell hypoxia. Partially lost cell membrane with increased caveolae, swollen mitochondria with degraded cristae, splintered ER, and increased lysosomes were evident in cell oxidative stress.

CONCLUSION

Human bladder smooth muscle cells are highly reactive to nonconforming oxygen tension. Reactions to hypoxia are consistent with cell survival signaling to cope with lack of oxygen. Changes in oxidative stress indicate extensive damage and deterioration of the subcellular elements. Hypoxic and oxidative damage may be an important mechanism of smooth muscle degeneration in bladder conditions with disturbed oxygen tension.

Endoplasmic reticulum stress and the unfolded protein response in nonalcoholic fatty liver disease

The underlying causes of nonalcoholic fatty liver disease (NAFLD) are unclear, although recent evidence has implicated the endoplasmic reticulum (ER) in both the development of steatosis and progression to nonalcoholic steatohepatitis. Disruption of ER homeostasis, often termed "ER stress," has been observed in liver and adipose tissue of humans with NAFLD and/or obesity. Importantly, the signaling pathway activated by disruption of ER homeostasis, the unfolded protein response, has been linked to lipid biosynthesis, insulin action, inflammation, and apoptosis. Therefore, understanding the mechanisms that disrupt ER homeostasis in NAFLD and the role of ER-mediated signaling have become topics of intense investigation. The present review will examine the ER and the unfolded protein response in the context of NAFLD.

Targeting histone deacetylases for the treatment of Huntington's disease

Huntington's disease is a debilitating neurodegenerative condition with significant burdens on both patient and healthcare costs. Despite the identification of the causative element, an expanded toxic polyglutamine tract in the mutant Huntingtin protein, treatment options for patients with this disease remain limited. In the following review I assess the current evidence suggesting that a family of important regulatory proteins known as histone deacetylases may be an important therapeutic target in the treatment of this disease.

Targeting Huntington's disease through histone deacetylases

Huntington’s disease (HD) is a debilitating neurodegenerative condition with significant burdens on both patient and healthcare costs. Despite extensive research, treatment options for patients with this condition remain limited. Aberrant post-translational modification (PTM) of proteins is emerging as an important element in the pathogenesis of HD. These PTMs include acetylation, phosphorylation, methylation, sumoylation and ubiquitination. Several families of proteins are involved with the regulation of these PTMs. In this review, I discuss the current evidence linking aberrant PTMs and/or aberrant regulation of the cellular machinery regulating these PTMs to HD pathogenesis. Finally, I discuss the evidence suggesting that pharmacologically targeting one of these protein families the histone deacetylases may be of potential therapeutic benefit in the treatment of HD.

Reperfusion does not induce oxidative stress but sustained endoplasmic reticulum stress in livers of rats subjected to traumatic-hemorrhagic shock

Oxidative stress is believed to accompany reperfusion and to mediate dysfunction of the liver after traumatic-hemorrhagic shock (THS). Recently, endoplasmic reticulum (ER) stress has been suggested as an additional factor. This study investigated whether reperfusion after THS leads to increased oxidative and/or ER stress in the liver. In a rat model, including laparotomy, bleeding until decompensation, followed by inadequate or adequate reperfusion phase, three time points were investigated: 40 min, 3 h, and 18 h after shock. The reactive oxygen and nitrogen species and its scavenging capacity (superoxide dismutase 2), the nitrotyrosine formation in proteins, and the lipid peroxidation together with the status of endogenous antioxidants (alpha-tocopherylquinone-alpha-tocopherol ratio) were investigated as markers for oxidative or nitrosylative stress. Mitochondrial function and cytochrome P450 isoform 1A1 activity were analyzed as representatives for hepatocyte function. Activation of the inositol-requiring enzyme 1/X-box binding protein pathway and up-regulation of the 78-kDa glucose-regulated protein were recorded as ER stress markers. Plasma levels of alanine aminotransferase and Bax/Bcl-XL messenger RNA (mRNA) ratio were used as indicators for hepatocyte damage and apoptosis induction. Oxidative or nitrosylative stress markers or representatives of hepatocyte function were unchanged during and short after reperfusion (40 min, 3 h after shock). In contrast, ER stress markers were elevated and paralleled those of hepatocyte damage. Incidence for sustained ER stress and subsequent apoptosis induction were found at 18 h after shock. Thus, THS or reperfusion induces early and persistent ER stress of the liver, independent of oxidative or nitrosylative stress. Although ER stress was not associated with depressed hepatocyte function, it may act as an early trigger of protracted cell death, thereby contributing to delayed organ failure after THS.

A mutant telomerase defective in nuclear-cytoplasmic shuttling fails to immortalize cells and is associated with mitochondrial dysfunction

Telomerase is a reverse transcriptase specialized in telomere synthesis. The enzyme is primarily nuclear where it elongates telomeres, but many reports show that the catalytic component of telomerase (in humans called hTERT) also localizes outside of the nucleus, including in mitochondria. Shuttling of hTERT between nucleus and cytoplasm and vice versa has been reported, and different proteins shown to regulate such translocation. Exactly why telomerase moves between subcellular compartments is still unclear. In this study we report that mutations that disrupt the nuclear export signal (NES) of hTERT render it nuclear but unable to immortalize cells despite retention of catalytic activity in vitro. Overexpression of the mutant protein in primary fibroblasts is associated with telomere-based cellular senescence, multinucleated cells and the activation of the DNA damage response genes ATM, Chk2 and p53. Mitochondria function is also impaired in the cells. We find that cells expressing the mutant hTERT produce high levels of mitochondrial reactive oxygen species and have damage in telomeric and extratelomeric DNA. Dysfunctional mitochondria are also observed in an ALT (alternative lengthening of telomeres) cell line that is insensitive to growth arrest induced by the mutant hTERT showing that mitochondrial impairment is not a consequence of the growth arrest. Our data indicate that mutations involving the NES of hTERT are associated with defects in telomere maintenance, mitochondrial function and cellular growth, and suggest targeting this region of hTERT as a potential new strategy for cancer treatment.