Endoplasmic reticulum stress induces autophagy through activation of p38 MAPK in fibroblasts from Pompe disease patients carrying c.546G>T mutation

From Acid Alpha-Glucosidase Deficiency to Autophagy: Understanding the Bases of POMPE Disease

Pompe disease (PD) is caused by mutations in the GAA gene, which encodes the lysosomal enzyme acid alpha-glucosidase, causing lysosomal glycogen accumulation, mainly in muscular tissue. Autophagic buildup is considered the main factor affecting skeletal muscle, although other processes are also involved. Uncovering how these mechanisms are interconnected could be an approximation to address long-lasting concerns, like the differential skeletal and cardiac involvement in each clinical phenotype. In this sense, a network reconstruction based on a comprehensive literature review of evidence found in PD enriched with the STRING database and other scientific articles is presented. The role of autophagic lysosome reformation, PGC-1α, MCOLN1, calcineurin, and Keap1 as intermediates between the events involved in the pathologic cascade is discussed and contextualized within their relationship with mTORC1/AMPK. The intermediates and mechanisms found open the possibility of new hypotheses and questions that can be addressed in future experimental studies of PD.

Dysregulation of Metabolism and Proteostasis in Skeletal Muscle of a Presymptomatic Pompe Mouse Model

Pompe disease is a rare genetic metabolic disorder caused by mutations in acid-alpha glucoside (GAA) leading to pathological lysosomal glycogen accumulation associated with skeletal muscle weakness, respiratory difficulties and cardiomyopathy, dependent from the GAA residual enzyme activity. This study aimed to investigate early proteomic changes in a mouse model of Pompe disease and identify potential therapeutic pathways using proteomic analysis of skeletal muscles from pre-symptomatic Pompe mice. For this purpose, quadriceps samples of Gaa^6neo/6neo mutant (Pompe) and wildtype mice, at the age of six weeks, were studied with three biological replicates for each group. The data were validated with skeletal muscle morphology, immunofluorescence studies and western blot analysis. Proteomic profiling identified 538 significantly upregulated and 16 significantly downregulated proteins in quadriceps muscles derived from Pompe animals compared to wildtype mice. The majority of significantly upregulated proteins were involved in metabolism, translation, folding, degrading and vesicular transport, with some having crucial roles in the etiopathology of other neurological or neuromuscular diseases. This study highlights the importance of the early diagnosis and treatment of Pompe disease and suggests potential add-on therapeutic strategies targeting protein dysregulations.

Correlation of GAA Genotype and Acid-α-Glucosidase Enzyme Activity in Hungarian Patients with Pompe Disease

Pompe disease is caused by the accumulation of glycogen in the lysosomes due to a deficiency of the lysosomal acid-α-glucosidase (GAA) enzyme. Depending on residual enzyme activity, the disease manifests two distinct phenotypes. In this study, we assess an enzymatic and genetic analysis of Hungarian patients with Pompe disease. Twenty-four patients diagnosed with Pompe disease were included. Enzyme activity of acid-α-glucosidase was measured by mass spectrometry. Sanger sequencing and an MLPA of the GAA gene were performed in all patients. Twenty (83.33%) patients were classified as having late-onset Pompe disease and four (16.66%) had infantile-onset Pompe disease. Fifteen different pathogenic GAA variants were detected. The most common finding was the c.-32-13 T > G splice site alteration. Comparing the α-glucosidase enzyme activity of homozygous cases to the compound heterozygous cases of the c.-32-13 T > G disease-causing variant, the mean GAA activity in homozygous cases was significantly higher. The lowest enzyme activity was found in cases where the c.-32-13 T > G variant was not present. The localization of the identified sequence variations in regions encoding the crucial protein domains of GAA correlates with severe effects on enzyme activity. A better understanding of the impact of pathogenic gene variations may help earlier initiation of enzyme replacement therapy (ERT) if subtle symptoms occur. Further information on the effect of GAA gene variation on the efficacy of treatment and the extent of immune response to ERT would be of importance for optimal disease management and designing effective treatment plans.

Three-dimensional tissue-engineered human skeletal muscle model of Pompe disease

In Pompe disease, the deficiency of the lysosomal enzyme acid alpha-glucosidase (GAA) causes skeletal and cardiac muscle weakness, respiratory failure, and premature death. While enzyme replacement therapy using recombinant human GAA (rhGAA) can significantly improve patient outcomes, detailed disease mechanisms and incomplete therapeutic effects require further studies. Here we report a three-dimensional primary human skeletal muscle ("myobundle") model of infantile-onset Pompe disease (IOPD) that recapitulates hallmark pathological features including reduced GAA enzyme activity, elevated glycogen content and lysosome abundance, and increased sensitivity of muscle contractile function to metabolic stress. In vitro treatment of IOPD myobundles with rhGAA or adeno-associated virus (AAV)-mediated hGAA expression yields increased GAA activity and robust glycogen clearance, but no improvements in stress-induced functional deficits. We also apply RNA sequencing analysis to the quadriceps of untreated and AAV-treated GAA-/- mice and wild-type controls to establish a Pompe disease-specific transcriptional signature and reveal novel disease pathways. The mouse-derived signature is enriched in the transcriptomic profile of IOPD vs. healthy myobundles and partially reversed by in vitro rhGAA treatment, further confirming the utility of the human myobundle model for studies of Pompe disease and therapy.

Cellular Stress in the Pathogenesis of Muscular Disorders-From Cause to Consequence

Cellular stress has been considered a relevant pathogenetic factor in a variety of human diseases. Due to its primary functions by means of contractility, metabolism, and protein synthesis, the muscle cell is faced with continuous changes of cellular homeostasis that require rapid and coordinated adaptive mechanisms. Hence, a prone susceptibility to cellular stress in muscle is immanent. However, studies focusing on the cellular stress response in muscular disorders are limited. While in recent years there have been emerging indications regarding a relevant role of cellular stress in the pathophysiology of several muscular disorders, the underlying mechanisms are to a great extent incompletely understood. This review aimed to summarize the available evidence regarding a deregulation of the cellular stress response in individual muscle diseases. Potential mechanisms, as well as involved pathways are critically discussed, and respective disease models are addressed. Furthermore, relevant therapeutic approaches that aim to abrogate defects of cellular stress response in muscular disorders are outlined.

Protein Misfolding Diseases and Therapeutic Approaches

Protein folding is the process by which a polypeptide chain acquires its functional, native 3D structure. Protein misfolding, on the other hand, is a process in which protein fails to fold into its native functional conformation. This misfolding of proteins may lead to precipitation of a number of serious diseases such as Cystic Fibrosis (CF), Alzheimer's Disease (AD), Parkinson's Disease (PD), and Amyotrophic Lateral Sclerosis (ALS) etc. Protein Quality-control (PQC) systems, consisting of molecular chaperones, proteases and regulatory factors, help in protein folding and prevent its aggregation. At the same time, PQC systems also do sorting and removal of improperly folded polypeptides. Among the major types of PQC systems involved in protein homeostasis are cytosolic, Endoplasmic Reticulum (ER) and mitochondrial ones. The cytosol PQC system includes a large number of component chaperones, such as Nascent-polypeptide-associated Complex (NAC), Hsp40, Hsp70, prefoldin and T Complex Protein-1 (TCP-1) Ring Complex (TRiC). Protein misfolding diseases caused due to defective cytosolic PQC system include diseases involving keratin/collagen proteins, cardiomyopathies, phenylketonuria, PD and ALS. The components of PQC system of Endoplasmic Reticulum (ER) include Binding immunoglobulin Protein (BiP), Calnexin (CNX), Calreticulin (CRT), Glucose-regulated Protein GRP94, the thiol-disulphide oxidoreductases, Protein Disulphide Isomerase (PDI) and ERp57. ER-linked misfolding diseases include CF and Familial Neurohypophyseal Diabetes Insipidus (FNDI). The components of mitochondrial PQC system include mitochondrial chaperones such as the Hsp70, the Hsp60/Hsp10 and a set of proteases having AAA+ domains similar to the proteasome that are situated in the matrix or the inner membrane. Protein misfolding diseases caused due to defective mitochondrial PQC system include medium-chain acyl-CoA dehydrogenase (MCAD)/Short-chain Acyl-CoA Dehydrogenase (SCAD) deficiency diseases, hereditary spastic paraplegia. Among therapeutic approaches towards the treatment of various protein misfolding diseases, chaperones have been suggested as potential therapeutic molecules for target based treatment. Chaperones have been advantageous because of their efficient entry and distribution inside the cells, including specific cellular compartments, in therapeutic concentrations. Based on the chemical nature of the chaperones used for therapeutic purposes, molecular, chemical and pharmacological classes of chaperones have been discussed.

Prevention of early liver metastasis after pancreatectomy by perioperative administration of a nuclear factor-κB inhibitor in mice

BACKGROUND

Liver metastasis is a common problem after pancreatectomy for pancreatic cancer. In pancreatic cancer cells, nuclear factor-κB is activated constitutively. Nuclear factor-κB activates matrix metalloproteinase-2/9, which plays an important role in cancer metastasis. Because the serine protease inhibitor FUT-175 suppresses nuclear factor-κB, we hypothesized that perioperative treatment with FUT-175 for pancreatic cancer may help to prevent liver metastasis.

METHODS

We compared in vitro cell viability, cell invasiveness, nuclear factor-κB signaling, and the expression levels of matrix metalloproteinase signals between the control group (C group) and the FUT-175 group (F group) using the murine pancreatic cancer cells PAN02. In addition, we evaluated the in vivo effect of pretreatment with FUT-175 using an established model of liver metastasis in mice. Metastatic liver lesions were assessed with magnetic resonance imaging. Liver recurrence and overall survival were evaluated. Also, the antimetastatic effect of systemic administration of FUT-175 was examined.

RESULTS

FUT-175 did not suppress the cell viability of PAN02 cells at or after 24 hours of treatment (P > .05); however, cell invasion was suppressed in the F group compared with the C group (P < .05). The levels of nuclear factor-κB activation, membrane type-1 (MT-1) matrix metalloproteinase (MMP)/matrix metalloproteinase-14 (MMP-14), and matrix metalloproteinase-2/9 (MMP-2/9) were lower in the F group compared with the C group. In vivo, both disease-free and overall survivals were prolonged in the F group compared with the C group. Systemic administration was also effective in suppressing the number of metastases.

CONCLUSION

Perioperative treatment with FUT-175 may help to prevent early liver metastasis after pancreatectomy for pancreatic cancer.

Mesenchymal stem cells inhibit T-cell function through conserved induction of cellular stress

The physiological role of mesenchymal stem cells (MSCs) is to provide a source of cells to replace mesenchymal-derivatives in stromal tissues with high cell turnover or following stromal tissue damage to elicit repair. Human MSCs have been shown to suppress in vitro T-cell responses via a number of mechanisms including indoleamine 2,3-dioxygenase (IDO). This immunomodulatory capacity is likely to be related to their in vivo function in tissue repair where local, transient suppression of immune responses would benefit differentiation. Further understanding of the impact of locally modulated immune responses by MSCs is hampered by evidence that IDO is not produced or utilized by mouse MSCs. In this study, we demonstrate that IDO-mediated tryptophan starvation triggered by human MSCs inhibits T-cell activation and proliferation through induction of cellular stress. Significantly, we show that despite utilizing different means, immunomodulation of murine T-cells also involves cellular stress and thus is a common strategy of immunoregulation conserved between mouse and humans.

New Insights into the Role of Endoplasmic Reticulum Stress in Breast Cancer Metastasis

Cellular stress severely disrupts endoplasmic reticulum (ER) function, leading to the abnormal accumulation of unfolded or misfolded proteins in the ER and subsequent development of endoplasmic reticulum stress (ERS). To accommodate the occurrence of ERS, cells have evolved a highly conserved, self-protecting signal transduction pathway called the unfolded protein response. Notably, ERS signaling is involved in the development of a variety of diseases and is closely related to tumor development, particularly in breast cancer. This review discusses recent research regarding associations between ERS and tumor metastasis. The information presented here will help researchers elucidate the precise mechanisms underlying ERS-mediated tumor metastasis and provide new directions for tumor therapies.

Stability of the ABCD1 Protein with a Missense Mutation: A Novel Approach to Finding Therapeutic Compounds for X-Linked Adrenoleukodystrophy

Mutations in the ABCD1 gene that encodes peroxisomal ABCD1 protein cause X-linked adrenoleukodystrophy (X-ALD), a rare neurodegenerative disorder. More than 70% of the patient fibroblasts with this missense mutation display either a lack or reduction of the ABCD1 protein because of posttranslational degradation. In this study, we analyzed the stability of the missense mutant ABCD1 proteins (p.A616T, p.R617H, and p.R660W) in X-ALD fibroblasts and found that the mutant ABCD1 protein p.A616T has the capacity to recover its function by incubating at low temperature. In the case of such a mutation, chemical compounds that stabilize mutant ABCD1 proteins could be therapeutic candidates. Here, we prepared CHO cell lines stably expressing ABCD1 proteins with a missense mutation in fusion with green fluorescent protein (GFP) at the C-terminal. The stability of each mutant ABCD1-GFP in CHO cells was similar to the corresponding mutant ABCD1 protein in X-ALD fibroblasts. Furthermore, it is of interest that the GFP at the C-terminal was degraded together with the mutant ABCD1 protein. These findings prompted us to use CHO cells expressing mutant ABCD1-GFP for a screening of chemical compounds that can stabilize the mutant ABCD1 protein. We established a fluorescence-based assay method for the screening of chemical libraries in an effort to find compounds that stabilize mutant ABCD1 proteins. The work presented here provides a novel approach to finding therapeutic compounds for X-ALD patients with missense mutations.

Pomalidomide enhanced gemcitabine and nab-paclitaxel on pancreatic cancer both in vitro and in vivo

Background

Chemotherapy with gemcitabine and nab-paclitaxel (gemcitabine/nab-paclitaxel) is recommended for unresectable pancreatic cancer. However, the therapeutic efficacy is attenuated by the antitumor agent-induced activation of nuclear factor-κB (NF-κB). Thalidomide inhibits NF-κB activation, therefore, we hypothesized that pomalidomide, a third-generation IMiD, would also inhibit NF-κB activation and enhance the antitumor effects of gemcitabine/nab-paclitaxel.

Methods

In vitro, we assessed NF-κB activity and apoptosis in response to pomalidomide alone, gemcitabine/nab-paclitaxel, or combination of pomalidomide and gemcitabine/nab-paclitaxel in human pancreatic cancer cell lines (PANC-1 and MIA PaCa-2). In vivo, we established orthotopic model and the animals were treated with oral pomalidomide and injection of gemcitabine/nab-paclitaxel.

Results

In pomalidomide and gemcitabine/nab-paclitaxel group, gemcitabine/nab-paclitaxel-induced NF-κB activation was inhibited and apoptosis was enhanced in comparison with those in the other groups both in vitro and in vivo. Especially, this study revealed for the first time that pomalidomide enhances p53 on pancreatic cancer cells. The tumor growth in the pomalidomide and gemcitabine/nab-paclitaxel group was significantly slower than that in the gemcitabine/nab-paclitaxel group. Moreover, pomalidomide induced G0/G1 cell cycle arrest and suppressed angiogenesis.

Conclusions

Pomalidomide enhanced the antitumor effect of gemcitabine/nab-paclitaxel by inhibition of NF-κB activation. This combination regimen would be a novel strategy for treating pancreatic cancer.

Autophagy mediated by endoplasmic reticulum stress enhances the caffeine-induced apoptosis of hepatic stellate cells

Caffeine has been identified to have beneficial effects against chronic liver diseases, particularly liver fibrosis. Many studies have reported that caffeine ameliorates liver fibrosis by directly inducing hepatic stellate cell (HSC) apoptosis; however, the molecular mechanisms involved in this process remain unclear. The presents study aimed to detect the underlying mechanisms by which caffeine mediates HSC apoptosis and eliminates activated HSCs. For this purpose, the LX-2 cell line was applied in this study and the cells were exposed to various concentrations of caffeine for the indicated times. The effects of caffeine on cell viability and apoptosis were assessed by Cell Counting Kit-8 assay and flow cytometry, respectively. Autophagy and endoplasmic reticulum (ER) stress were explored by morphological assessment and western blotting. In the present study, caffeine was found to inhibit the viability and increase the apoptosis of the LX-2 cells in dose- and time-dependent manners. ER stress was stimulated by caffeine as demonstrated by increased levels of GRP78/BiP, CHOP and inositol-requiring enzyme 1 (IRE1)-α as well as many enlarged ERs detected by electron microscopy. Caffeine induced autophagy as shown by increased p62 and LC3II accumulation and the number of GFP/RFP-LC3 puncta and autophagosomes/autolysosomes. Moreover, IRE1-α knockdown decreased the level of autophagic flux, and inhibition of autophagy protected LX-2 cells from apoptotic death. In conclusion, our study showed that the caffeine-enhanced autophagic flux in HSCs was stimulated by ER stress via the IRE1-α signaling pathway, which further weakened HSC viability via the induction of apoptosis. These findings provide new insight into the mechanism of caffeine's anti-fibrotic effects.

Glycogen synthase kinase-3β activity plays a key role in the antitumor effect of nafamostat mesilate in pancreatic cancer cells

Pancreatic cancer is often resistant to chemotherapy. We previously showed the efficacy of combination treatment using gemcitabine and nafamostat mesilate (FUT‐175) for patients with unresectable pancreatic cancer. However, the mechanisms that affect the sensitivity of FUT‐175 are not fully understood. The purpose of the present study was to clarify the mechanism of the sensitivity to FUT‐175, with a focus on the activity of glycogen synthase kinase‐3β (GSK‐3β). In vitro, we assessed sensitivity to FUT‐175 in human pancreatic cancer cell lines (PANC‐1 and MIAPaCa‐2) and difference of signaling in these cells by cell proliferation assay, Western blot analysis and microarray. Next, we assessed cell viability, apoptotic signal and nuclear factor‐kappa B (NF‐κB) activity in response to treatment with FUT‐175 alone and in combination with GSK‐3 inhibitor or protein phosphatase 2A (PP2A) by cell proliferation assay, Western blot analysis and enzyme‐linked immunosorbent assay. Phosphorylated GSK‐3β level was significantly higher in MIAPaCa‐2 (high sensitivity cell) than in PANC‐1 (low sensitivity cell). Cell viability and NF‐κB activity were significantly decreased by addition of GSK‐3 inhibitor to FUT‐175, and levels of cleaved caspase‐8 were increased by inhibition of GSK‐3. PP2A inhibitor increased the levels of phosphorylated GSK‐3β and sensitized both cell lines to FUT‐175 as measured by cell viability and apoptotic signal. The results indicate that GSK‐3β activity plays a key role in the antitumor effect of FUT‐175 in pancreatic cancer cells, and regulation of GSK‐3β by PP2A inhibition could be a novel therapeutic approach for pancreatic cancer.

Effect of rapamycin treatment during post-activation and/or in vitro culture on embryonic development after parthenogenesis and in vitro fertilization in pigs

This study investigated the effects of early induction of autophagy on embryonic development in pigs. For this, oocytes or embryos were treated with an autophagy inducer, rapamycin (RP), during post-activation (Pa), in vitro fertilization (IVF) and/or in vitro culture (IVC). When parthenogenesis (PA) embryos were untreated (control) or treated with various concentrations of RP for 4 hr during Pa, 100 nm RP showed a higher blastocyst formation (48.8 ± 2.7%) than the control (34.6 ± 3.0%). When PA embryos were treated during the first 24 hr of IVC, blastocyst formation was increased (p < .05) by 1 and 10 nm RP (61.9 ± 3.0 and 59.6 ± 3.0%, respectively) compared to the control (43.2 ± 1.8%) and 100 nm RP (47.8 ± 3.2%), with a higher embryo cleavage in response to 10 nm RP (87.3 ± 2.4%) than the control (74.1 ± 3.2%). RP treatment during IVC and Pa + IVC showed increased blastocyst formation (44.7 ± 2.5 and 44.1 ± 2.0%, respectively) compared to the control (33.2 ± 2.0%). In addition, RP treatment during Pa and/or IVC increased glutathione content and inversely reduced reactive oxygen species. In IVF, RP treatment for 6 hr during IVF significantly increased embryonic development (34.0 ± 2.6%) compared to the control (24.8 ± 1.6%), but treatment during IVC for 24 hr with RP did not (23.0 ± 3.8%). Autophagy was significantly increased in PA oocytes by the RP treatment during Pa but not altered by the treatment during the first 24 hr of IVC. Overall, RP treatment positively regulated the pre-implantation development of pig embryos, probably by regulating cellular redox state and stimulating autophagy.

Carbohydrate-Processing Enzymes of the Lysosome: Diseases Caused by Misfolded Mutants and Sugar Mimetics as Correcting Pharmacological Chaperones

Lysosomal storage diseases are hereditary disorders caused by mutations on genes encoding for one of the more than fifty lysosomal enzymes involved in the highly ordered degradation cascades of glycans, glycoconjugates, and other complex biomolecules in the lysosome. Several of these metabolic disorders are associated with the absence or the lack of activity of carbohydrate-processing enzymes in this cell compartment. In a recently introduced therapy concept, for susceptible mutants, small substrate-related molecules (so-called pharmacological chaperones), such as reversible inhibitors of these enzymes, may serve as templates for the correct folding and transport of the respective protein mutant, thus improving its concentration and, consequently, its enzymatic activity in the lysosome. Carbohydrate-processing enzymes in the lysosome, related lysosomal diseases, and the scope and limitations of reported reversible inhibitors as pharmacological chaperones are discussed with a view to possibly extending and improving research efforts in this area of orphan diseases.

Metabolomic Profiling of Pompe Disease-Induced Pluripotent Stem Cell-Derived Cardiomyocytes Reveals That Oxidative Stress Is Associated with Cardiac and Skeletal Muscle Pathology

Pompe disease (PD) is a lysosomal storage disease that is caused by a deficiency of the acid α‐glucosidase, which results in glycogen accumulation in the lysosome. The major clinical symptoms of PD include skeletal muscle weakness, respiratory failure, and cardiac hypertrophy. Based on its severity and symptom onset, PD is classified into infantile and late‐onset forms. Lysosomal accumulation of glycogen can promote many types of cellular dysfunction, such as autophagic dysfunction, endoplasmic reticulum stress, and abnormal calcium signaling within skeletal muscle. However, the disease mechanism underlying PD cardiomyopathy is not fully understood. Several researchers have shown that PD induced pluripotent stem cell (iPSC)‐derived cardiomyocytes successfully replicate the disease phenotype and are useful disease models. We have analyzed the metabolomic profile of late‐onset PD iPSC‐derived cardiomyocytes and found that oxidative stress and mitochondrial dysfunction are likely associated with cardiac complications. Furthermore, we have validated that these disease‐specific changes were also observed in the cardiomyocytes and skeletal muscle of a genetically engineered murine PD model. Oxidative stress may contribute to skeletal muscle and cardiomyocyte dysfunction in PD mice; however, NF‐E2‐related factor 2 was downregulated in cardiomyocytes and skeletal muscle, despite evidence of oxidative stress. We hypothesized that oxidative stress and an impaired antioxidative stress response mechanism may underlie the molecular pathology of late‐onset PD. Stem Cells Translational Medicine2017;6:31–39

Carnosic acid slows photoreceptor degeneration in the Pde6b(rd10) mouse model of retinitis pigmentosa

The photoreceptor cell death associated with the various genetic forms of retinitis pigmentosa (RP) is currently untreatable and leads to partial or complete vision loss. Carnosic acid (CA) upregulates endogenous antioxidant enzymes and has proven neuroprotective in studies of neurodegenerative models affecting the brain. In this study, we examined the potential effect of CA on photoreceptor death in the Pde6b^rd10 mouse model of RP. Our data shows that CA provided morphological and functional preservation of photoreceptors. CA appears to exert its neuroprotective effects through inhibition of oxidative stress and endoplasmic reticulum stress.

Interplay between unfolded protein response and autophagy promotes tumor drug resistance

The endoplasmic reticulum (ER) is involved in the quality control of secreted protein via promoting the correct folding of nascent protein and mediating the degradation of unfolded or misfolded protein, namely ER-associated degradation. When the unfolded or misfolded proteins are abundant, the unfolded protein response (UPR) is elicited, an adaptive signaling cascade from the ER to the nucleus, which restores the homeostatic functions of the ER. Autophagy is a conserved catabolic process where cellular long-lived proteins and damaged organelles are engulfed and degraded for recycling to maintain homeostasis. The UPR and autophagy occur simultaneously and are involved in pathological processes, including tumorigenesis, chemoresistance of malignancies and neurodegeneration. Accumulative data has indicated that the UPR may induce autophagy and that autophagy is able to alleviate the UPR. However, the detailed mechanism of interplay between autophagy and UPR remains to be fully understood. The present review aimed to depict the core pathways of the two processes and to elucidate how autophagy and UPR are regulated. Moreover, the review also discusses the molecular mechanism of crosstalk between the UPR and autophagy and their roles in malignant survival and drug resistance.

The roles of endoplasmic reticulum stress response in female mammalian reproduction

Endoplasmic reticulum stress (ERS) activates a protective pathway, called the unfold protein response, for maintaining cellular homeostasis, but cellular apoptosis is triggered by excessive or persistent ERS. Several recent studies imply that the ERS response might have broader physiological roles in the various reproductive processes of female mammals, including embryo implantation, decidualization, preimplantation embryonic development, follicle atresia, and the development of the placenta. This review summarizes the existing data concerning the molecular and biological roles of the ERS response. The study of the functions of the ERS response in mammalian reproduction might provide novel insights into and an understanding of reproductive cell survival and apoptosis under physiological and pathological conditions. The ERS response is a novel signaling pathway for reproductive cell survival and apoptosis. Infertility might be a result of disturbing the ERS response during the process of female reproduction.

The role of endoplasmic reticulum stress in endothelial dysfunction induced by homocysteine thiolactone

Our and other studies have reported that homocysteine thiolactone (HTL) could induce endothelial dysfunction. However, the precise mechanism was largely unknown. In this study, we tested the most possible factor-endoplasmic reticulum (ER) stress, which was demonstrated to be involved in endothelial dysfunction in cardiovascular disease. Acetylcholine (Ach)-induced endothelium-dependent relaxation (EDR) and biochemical parameters were measured in rat isolated aorta. The level of reactive oxygen species (ROS) and NO was designed by specific fluorescent probe DCFH-DA and DAF-FM DA separately. The nuclear translocation of the NF-κB was studied by immune-fluorescence. The mRNA expression and protein expression of GRP78--a key indicator for the induction of ER stress--were assessed by real-time PCR and Western blot. Two ER stress inhibitors-4-PBA (5 mm) and Tudca (500 μg/mL)--significantly prevented HTL-impaired EDR and increased NO release, endothelial nitric oxide synthase (eNOS) and SOD activity, decreased ROS production, NADPH activity, NOX-4 mRNA and MDA level. We also found that 4-PBA and Tudca blocked HTL--induced NF-κB activation thus inhibiting the downstream target gene production including TNF-α and ICAM-1. Simultaneously, HTL increased the mRNA and protein level of GRP78. HTL could induce ER stress leading to a downstream enhancement of oxidative stress and inflammation, which finally caused vascular endothelial dysfunction.

Exercise-induced skeletal muscle remodeling and metabolic adaptation: redox signaling and role of autophagy

SIGNIFICANCE

Skeletal muscle is a highly plastic tissue. Exercise evokes signaling pathways that strongly modify myofiber metabolism and physiological and contractile properties of skeletal muscle. Regular physical activity is beneficial for health and is highly recommended for the prevention of several chronic conditions. In this review, we have focused our attention on the pathways that are known to mediate physical training-induced plasticity.

RECENT ADVANCES

An important role for redox signaling has recently been proposed in exercise-mediated muscle remodeling and peroxisome proliferator-activated receptor γ (PPARγ) coactivator-1α (PGC-1α) activation. Still more currently, autophagy has also been found to be involved in metabolic adaptation to exercise.

CRITICAL ISSUES

Both redox signaling and autophagy are processes with ambivalent effects; they can be detrimental and beneficial, depending on their delicate balance. As such, understanding their role in the chain of events induced by exercise and leading to skeletal muscle remodeling is a very complicated matter. Moreover, the study of the signaling induced by exercise is made even more difficult by the fact that exercise can be performed with several different modalities, with this having different repercussions on adaptation.

FUTURE DIRECTIONS

Unraveling the complexity of the molecular signaling triggered by exercise on skeletal muscle is crucial in order to define the therapeutic potentiality of physical training and to identify new pharmacological compounds that are able to reproduce some beneficial effects of exercise. In evaluating the effect of new "exercise mimetics," it will also be necessary to take into account the involvement of reactive oxygen species, reactive nitrogen species, and autophagy and their controversial effects.

The generation of induced pluripotent stem cells (iPSCs) from patients with infantile and late-onset types of Pompe disease and the effects of treatment with acid-α-glucosidase in Pompe's iPSCs

Pompe disease (PD), which is also called glycogen storage disease type II (GSDII), is one of the lysosomal storage diseases (LSDs) caused by a deficiency in acid-α-glucosidase (GAA) in the lysosome and is characterized by the accumulation of glycogen in various cells. PD has been treated by enzyme replacement therapy (ERT). We generated induced pluripotent stem cells (iPSCs) from the cells of patients with infantile-type and late-onset-type PD using a retrovirus vector to deliver transgenes encoding four reprogramming factors, namely, OCT4, SOX2, c-MYC, and KLF4. We confirmed that the two types of PD-iPSCs exhibited an undifferentiated state, alkaline phosphatase staining, and the presence of SSEA-4, TRA-1-60, and TRA-1-81. The PD-iPSCs exhibited strong positive staining with Periodic acid-Schiff (PAS). Moreover, ultrastructural features of these iPSCs exhibited massive glycogen granules in the cytoplasm, particularly in the infantile-type but to a lesser degree in the late-onset type. Glycogen granules of the infantile-type iPSCs treated with rhGAA were markedly decreased in a dose-dependent manner. Human induced pluripotent stem cell provides an opportunity to build up glycogen storage of Pompe disease in vitro. It represents a promising resource to study disease mechanisms, screen new drug compounds and develop new therapies for Pompe disease.

Sequential treatment of HPV E6 and E7-expressing TC-1 cells with bortezomib and celecoxib promotes apoptosis through p-p38 MAPK-mediated downregulation of cyclin D1 and CDK2

Interruption of the cell cycle is accompanied by changes in several related molecules that result in the activation of apoptosis. The present study was performed to verify the apoptotic effects of sequential treatment with bortezomib and celecoxib in TC-1 cells expressing the human papillomavirus (HPV) E6 and E7 proteins. In TC-1 cells sequentially treated with bortezomib and celecoxib, apoptosis was induced through decreased expression of signal transducer and activator of transcription-3 (STAT3), cyclin D1 and cyclin-dependent kinase (CDK) 2, which are major regulators of the G0/G1 cell cycle checkpoint. In addition, increased levels of p21, CHOP, BiP and p-p38 MAPK were identified in these cells. The treatment-induced apoptosis was effectively inhibited by treatment with SB203580, an inhibitor of p-p38. Moreover, the growth of tumors sequentially treated with bortezomib and celecoxib was retarded compared to the growth of tumors exposed to a single treatment with either bortezomib or celecoxib in vivo. We demonstrated that sequential treatment with bortezomib and celecoxib induced apoptosis via p-p38-mediated G0/G1 cell cycle arrest and endoplasmic reticulum (ER) stress. Sequential treatment with these two drugs could therefore be a useful therapy for cervical cancer.

Mechanism of endoplasmic reticulum stress-induced vascular endothelial dysfunction

BACKGROUND

We recently reported that ER stress plays a key role in vascular endothelial dysfunction during hypertension. In this study we aimed to elucidate the mechanisms by which ER stress induction and oxidative stress impair vascular endothelial function.

METHODOLOGY/PRINCIPAL FINDINGS

We conducted in vitro studies with primary endothelial cells from coronary arteries stimulated with tunicamycin, 1μg/mL, in the presence or absence of two ER stress inhibitors: tauroursodeoxycholic acid (Tudca), 500μg/mL, and 4-phenylbutyric acid (PBA), 5mM. ER stress induction was assessed by enhanced phosphorylation of PERK and eIF2α, and increased expression of CHOP, ATF6 and Grp78/Bip. The ER stress induction increased p38 MAPK phosphorylation, Nox2/4 mRNA levels and NADPH oxidase activity, and decreased eNOS promoter activity, eNOS expression and phosphorylation, and nitrite levels. Interestingly, the inhibition of p38 MAPK pathway reduced CHOP and Bip expressions enhanced by tunicamycin and restored eNOS promoter activation as well as phosphorylation. To study the effects of ER stress induction in vivo, we used C57BL/6J mice and p47phox(-/-) mice injected with tunicamycin or saline. The ER stress induction in mice significantly impaired vascular endothelium-dependent and independent relaxation in C57BL/6J mice compared with p47phox(-/-) mice indicating NADPH oxidase activity as an intermediate for ER stress in vascular endothelial dysfunction.

CONCLUSION/SIGNIFICANCE

We conclude that chemically induced ER stress leads to a downstream enhancement of p38 MAPK and oxidative stress causing vascular endothelial dysfunction. Our results indicate that inhibition of ER stress could be a novel therapeutic strategy to attenuate vascular dysfunction during cardiovascular diseases.

Screening of kinase inhibitors targeting BRAF for regulating autophagy based on kinase pathways

The aim of this study was to identify agents that regulate autophagy. A total of 544 differentially expressed genes were screened from the intersection set of GSE2435 and GSE31040, which was obtained from the Gene Expression Omnibus database and 19 differentially expressed kinases were selected according to a 'protein kinase database'. Gene ontology‑biological process (GO-BP) enrichment analysis revealed that the 19 kinases were mainly associated with phosphorylation. The protein-protein interaction network exhibited 30 differentially expressed genes that interacted with BRAF, and GO-BP enrichment analysis showed the function of these genes were mainly involved in cell death and apoptosis. The kinase-kinase inhibitor regulatory network identified16 kinase inhibitors that specifically inhibited BRAF. Previous studies indicated that sorafenib is capable of regulating autophagy and regorafenib has also been reported; however, there have been no studies regarding the regulation of autophagy by afatinib, selumetinib, PD318088, axitinib, TAK-733, GDC-0980, GSK2126458, PLX-4720, AS703026, trametinib, GDC-0941 and PF-04217903. Thus, these kinase inhibitors are potential targets for further study on the regulation of autophagy in the future.

Developing therapeutic approaches for metachromatic leukodystrophy

Metachromatic leukodystrophy (MLD) is an autosomal recessive lysosomal disorder caused by the deficiency of arylsulfatase A (ASA), resulting in impaired degradation of sulfatide, an essential sphingolipid of myelin. The clinical manifestations of MLD are characterized by progressive demyelination and subsequent neurological symptoms resulting in severe debilitation. The availability of therapeutic options for treating MLD is limited but expanding with a number of early stage clinical trials already in progress. In the development of therapeutic approaches for MLD, scientists have been facing a number of challenges including blood–brain barrier (BBB) penetration, safety issues concerning therapies targeting the central nervous system, uncertainty regarding the ideal timing for intervention in the disease course, and the lack of more in-depth understanding of the molecular pathogenesis of MLD. Here, we discuss the current status of the different approaches to developing therapies for MLD. Hematopoietic stem cell transplantation has been used to treat MLD patients, utilizing both umbilical cord blood and bone marrow sources. Intrathecal enzyme replacement therapy and gene therapies, administered locally into the brain or by generating genetically modified hematopoietic stem cells, are emerging as novel strategies. In pre-clinical studies, different cell delivery systems including microencapsulated cells or selectively neural cells have shown encouraging results. Small molecules that are more likely to cross the BBB can be used as enzyme enhancers of diverse ASA mutants, either as pharmacological chaperones, or proteostasis regulators. Specific small molecules may also be used to reduce the biosynthesis of sulfatides, or target different affected downstream pathways secondary to the primary ASA deficiency. Given the progressive neurodegenerative aspects of MLD, also seen in other lysosomal diseases, current and future therapeutic strategies will be complementary, whether used in combination or separately at specific stages of the disease course, to produce better outcomes for patients afflicted with this devastating inherited disorder.

Phenotype-genotype correlations in patients with Marinesco-Sjögren syndrome

Marinesco-Sjögren syndrome (MSS; MIM 248800) is an autosomal recessive disorder characterized by congenital cerebellar ataxia, early cataracts, developmental delay, myopathy and short stature. Alterations in the gene SIL1 cause MSS in some patients with typical findings. In this study, molecular investigations including sequencing of the SIL1 gene, western blotting and microscopic investigations in fibroblast cultures were carried out in a cohort of 15 patients from 14 unrelated families, including the large, inbred family reported by Superneau et al., having the clinical features of MSS to provide insights into the pathophysiology of the disorder. A total of seven different mutations were found in eight of the patients from seven families. The mutations caused loss of the BIP-associated protein (BAP) protein in four patients by western blot. Novel clinical features such as dental abnormalities, iris coloboma, eczema and hormonal abnormalities were noticed in some patients, but there was no clear way to distinguish those with and without SIL1 mutations. Cultured fibroblasts contained numerous cytoplasmic inclusion bodies, similar to those identified in the brain of the whoozy mouse in five unrelated patients, three with and two without SIL1 mutations, suggesting some SIL1 negative patients share a common cellular pathogenesis with those who are SIL1 positive.

Endoplasmic reticulum stress induces fibrogenic activity in hepatic stellate cells through autophagy

BACKGROUND & AIMS

Metabolic stress during liver injury enhances autophagy and provokes stellate cell activation, with secretion of scar matrix. Conditions that augment protein synthesis increase demands on the endoplasmic reticulum (ER) folding capacity and trigger the unfolded protein response (UPR) to cope with resulting ER stress. Generation of reactive oxygen species (ROS) is a common feature of hepatic fibrogenesis, and crosstalk between oxidant stress and ER stress has been proposed. The aim of our study was to determine the impact of oxidant and ER stress on stellate cell activation.

METHODS

Oxidant stress was induced in hepatic stellate cells using H2O2 in culture or by ethanol feeding in vivo, and the UPR was analyzed. Because the branch of the UPR mainly affected was IREα, we blocked this pathway in stellate cells and analyzed the fibrogenic response, together with autophagy and downstream MAPK signaling. The Nrf2 antioxidant response was also evaluated in stellate cells under oxidant stress conditions.

RESULTS

H2O2 treatment in culture or ethanol feeding in vivo increased the UPR based on splicing of XBP1 mRNA, which triggered autophagy. The Nrf2-mediated antioxidant response, as measured by qRT-PCR of its target genes was also induced under ER stress conditions. Conversely, blockade of the IRE1α pathway in stellate cells significantly decreased both their activation and autophagic activity in a p38 MAPK-dependent manner, leading to a reduced fibrogenic response.

CONCLUSIONS

These data implicate mechanisms underlying protein folding quality control in regulating the fibrogenic response in hepatic stellate cells.

Functions of autophagy in normal and diseased liver

Autophagy has emerged as a critical lysosomal pathway that maintains cell function and survival through the degradation of cellular components such as organelles and proteins. Investigations specifically employing the liver or hepatocytes as experimental models have contributed significantly to our current knowledge of autophagic regulation and function. The diverse cellular functions of autophagy, along with unique features of the liver and its principal cell type the hepatocyte, suggest that the liver is highly dependent on autophagy for both normal function and to prevent the development of disease states. However, instances have also been identified in which autophagy promotes pathological changes such as the development of hepatic fibrosis. Considerable evidence has accumulated that alterations in autophagy are an underlying mechanism of a number of common hepatic diseases including toxin-, drug- and ischemia/reperfusion-induced liver injury, fatty liver, viral hepatitis and hepatocellular carcinoma. This review summarizes recent advances in understanding the roles that autophagy plays in normal hepatic physiology and pathophysiology with the intent of furthering the development of autophagy-based therapies for human liver diseases.

Akt inactivation induces endoplasmic reticulum stress-independent autophagy in fibroblasts from patients with Pompe disease

Pompe disease (glycogen storage disease type II) is an autosomal recessive neuromuscular disorder arising from a deficiency of lysosomal acid α-glucosidase (GAA). Accumulation of autophagosomes is a key pathological change in skeletal muscle fibers and fibroblasts from patients with Pompe disease and is implicated in the poor response to enzyme replacement therapy (ERT). We previously found that mutant GAA-induced endoplasmic reticulum (ER) stress initiated autophagy in patient fibroblasts. However, the mechanism of induction of autophagy in fibroblasts from Pompe disease patients lacking ER stress remains unclear. In this study, we show that inactivated Akt induces ER stress-independent autophagy via mTOR suppression in patient fibroblasts. Activated autophagy as evidenced by increased levels of LC3-II and autophagic vesicles was observed in patient fibroblasts, whereas PERK phosphorylation reflecting the presence of ER stress was not observed in them. These patient fibroblasts showed decreased levels of not only phosphorylated Akt, but also phosphorylated p70 S6 kinase. Treatment with insulin, which acts as an activator of the Akt signaling pathway, resulted in increased phosphorylation of both Akt and p70 S6 kinase and suppression of autophagy in patient fibroblasts. In addition, following combination treatment with recombinant human GAA plus insulin, enhanced localization of the enzymes with lysosomes was observed in patient fibroblasts. These findings define a critical role of Akt suppression in the induction of autophagy in fibroblasts from patients with Pompe disease carrying an ER stress non-inducible mutation, and they provide evidence that insulin may potentiate the effect of ERT.

Hyperammonemia-mediated autophagy in skeletal muscle contributes to sarcopenia of cirrhosis

Hyperammonemia and sarcopenia (loss of skeletal muscle) are consistent abnormalities in cirrhosis and portosystemic shunting. We have shown that muscle ubiquitin-proteasome components are not increased with hyperammonemia despite sarcopenia. This suggests that an alternative mechanism of proteolysis contributes to sarcopenia in cirrhosis. We hypothesized that autophagy could be this alternative pathway since we observed increases in classic autophagy markers, increased LC3 lipidation, beclin-1 expression, and p62 degradation in immunoblots of skeletal muscle protein in cirrhotic patients. We observed similar changes in these autophagy markers in the portacaval anastamosis (PCA) rat model. To determine the mechanistic relationship between hyperammonemia and autophagy, we exposed murine C(2)C(12) myotubes to ammonium acetate. Significant increases in LC3 lipidation, beclin-1 expression, and p62 degradation occurred by 1 h, whereas autophagy gene expression (LC3, Atg5, Atg7, beclin-1) increased at 24 h. C(2)C(12) cells stably expressing GFP-LC3 or GFP-mCherry-LC3 constructs showed increased formation of mature autophagosomes supported by electron microscopic studies. Hyperammonemia also increased autophagic flux in mice, as quantified by an in vivo autophagometer. Because hyperammonemia induces nitration of proteins in astrocytes, we quantified global muscle protein nitration in cirrhotic patients, in the PCA rat, and in C(2)C(12) cells treated with ammonium acetate. Increased protein nitration was observed in all of these systems. Furthermore, colocalization of nitrated proteins with GFP-LC3-positive puncta in hyperammonemic C(2)C(12) cells suggested that autophagy is involved in degradation of nitrated proteins. These observations show that increased skeletal muscle autophagy in cirrhosis is mediated by hyperammonemia and may contribute to sarcopenia of cirrhosis.

Participation of endoplasmic reticulum stress in the pathogenesis of spontaneous glomerulosclerosis--role of intra-renal angiotensin system

Endoplasmic reticulum (ER) is the site of synthesis, folding, assembly, and degradation of proteins. Disruption of ER function leads to ER stress, which is marked by accumulation of unfolded proteins in the ER lumen. Detection of unfolded proteins by the ER membrane receptors triggers the "unfolded protein response (UPR)" designed to restore ER function via activation of the adaptive/cytoprotective responses. Failure of UPR or persistent stress triggers activation of ER stress-mediated apoptotic pathway. Several in vivo and in vitro studies have demonstrated the association of ER stress with glomerular diseases. Imai rats develop progressive glomerulosclerosis (GS), which is associated with oxidative stress, inflammation and activation of intra-renal angiotensin system, and can be prevented by AT-1 receptor blockade (ARB). Since persistent oxidative and inflammatory stresses trigger ER stress-induced apoptosis and tissue injury, we hypothesized that kidneys in the Imai rats may exhibit failure of the adaptive and activation of the apoptotic ER stress responses, which could be prevented by ARB. To this end 10-week old Imai rats were randomized to untreated and ARB-treated groups and observed for 24 weeks. At age 34 weeks, untreated rats showed heavy proteinuria, azotemia, advanced GS, impaired ER stress adaptive/cytoprotective responses (depletion of UPR-mediating proteins), and activation of ER stress apoptotic responses. ARB treatment attenuated GS, suppressed intra-renal oxidative stress, restored ER-associated adaptive/cytoprotective system, and prevented the ER stress mediated apoptotic response in this model. Thus, progressive GS in Imai rats is accompanied by activation of ER stress-associated apoptosis, which can be prevented by ARB.

CARM1/PRMT4 is necessary for the glycogen gene expression programme in skeletal muscle cells

CARM1 (co-activator-associated arginine methyltransferase 1)/PRMT4 (protein arginine methyltransferase 4), functions as a co-activator for transcription factors that are regulators of muscle fibre type and oxidative metabolism, including PGC (peroxisome-proliferator-activated receptor γ co-activator)-1α and MEF2 (myocyte enhancer factor 2). We observed significantly higher Prmt4 mRNA expression in comparison with Prmt1-Prmt6 mRNA expression in mouse muscle (in vitro and in vivo). Transfection of Prmt4 siRNA (small interfering RNA) into mouse skeletal muscle C2C12 cells attenuated PRMT4 mRNA and protein expression. We subsequently performed additional qPCR (quantitative PCR) analysis (in the context of metabolism) to examine the effect of Prmt4 siRNA expression on >200 critical genes that control (and are involved in) lipid, glucose and energy homoeostasis, and circadian rhythm. This analysis revealed a strikingly specific metabolic expression footprint, and revealed that PRMT4 is necessary for the expression of genes involved in glycogen metabolism in skeletal muscle cells. Prmt4 siRNA expression selectively suppressed the mRNAs encoding Gys1 (glycogen synthase 1), Pgam2 (muscle phosphoglycerate mutase 2) and Pygm (muscle glycogen phosphorylase). Significantly, PGAM, PYGM and GYS1 deficiency in humans causes glycogen storage diseases type X, type V/McArdle's disease and type 0 respectively. Attenuation of PRMT4 was also associated with decreased expression of the mRNAs encoding AMPK (AMP-activated protein kinase) α2/γ3 (Prkaa2 and Prkag3) and p38 MAPK (mitogen-activated protein kinase), previously implicated in Wolff-Parkinson-White syndrome and Pompe Disease (glycogen storage disease type II). Furthermore, stable transfection of two PRMT4-site-specific (methyltransferase deficient) mutants (CARM1/PRMT4 VLD and CARM1E267Q) significantly repressed the expression of Gys1, Pgam2 and AMPKγ3. Finally, in concordance, we observed increased and decreased glycogen levels in PRMT4 (native)- and VLD (methylation deficient mutant)-transfected skeletal muscle cells respectively. This demonstrated that PRMT4 expression and the associated methyltransferase activity is necessary for the gene expression programme involved in glycogen metabolism and human glycogen storage diseases.

Induction of autophagy promotes preattachment development of bovine embryos by reducing endoplasmic reticulum stress

The coupling of autophagy and endoplasmic reticulum (ER) stress has been implicated in a variety of biological processes; however, little is known regarding the involvement of the autophagy/ER stress pathway in early embryogenesis or the underlying mechanism(s). Here, we showed that the developmental competence of in vitro-produced (IVP) bovine embryos was highly dependent on the autophagy/ER stress balance. Although relative abundances of autophagy-associated gene transcripts, including LC3, Atg5, and Atg7 transcripts, were high in oocytes and throughout the early stages of preattachment development, extensive autophagosome formation was only detected in fertilized embryos. Using an inducer and inhibitor of autophagy, we showed that transient elevation of autophagic activity during early preattachment development greatly increased the blastocyst development rate, trophectoderm cell numbers, and blastomere survival; these same parameters were reduced by both inhibition and prolonged induction of autophagy. Interestingly, the induction of autophagy reduced ER stress and associated damage, while the developmental defects in autophagy-inhibited embryos were significantly alleviated by ER stress inhibitor treatment, indicating that autophagy is a negative regulator of ER stress in early embryos. Collectively, these results suggest that early embryogenesis of IVP bovine embryos depends on an appropriate balance between autophagy and ER stress. These findings may increase our understanding of important early developmental events by providing compelling evidence concerning the tight association between autophagy and ER stress, and may contribute to the development of strategies for the production of IVP bovine blastocysts with high developmental competence.

Resveratrol protects H9c2 embryonic rat heart derived cells from oxidative stress by inducing autophagy: role of p38 mitogen-activated protein kinase

Recently, many studies have attempted to illustrate the mechanism of autophagy in protection against oxidative stress to the heart induced by H2O2. However, whether resveratrol-induced autophagy involves the p38 mitogen-activated protein kinase (MAPK) pathway is still unknown. This study aimed to investigate whether treating H9c2 cells with resveratrol increases autophagy and attenuates the cell death and apoptosis induced by oxidative stress via the p38 MAPK pathway. Resveratrol with or without SB202190, an inhibitor of the p38 MAPK pathway, was added 30 min before H2O2. After H2O2 treatment, the cells were incubated under 5% CO2 at 37 °C for 24 h to assess cell survival and death or incubated for 20 min for Western blot and transmission electron microscopy. Flow cytometry was used to detect apoptosis after 6 h of H2O2 treatment. Resveratrol at 20 µmol/L protected H9c2 cells treated with 100 µmol/L H2O2 from oxidative damage. It increased cell survival and markedly decrease lactate dehydrogenase release. In addition, resveratrol increased autophagy and decreased H2O2-induced apoptosis. Furthermore, the protective effects of resveratrol were inhibited by 10 µmol/L SB202190. Thus, resveratrol protected H2O2-treated H9c2 cells by upregulating autophagy via the p38 MAPK pathway.

The interplay between endoplasmic reticulum stress and inflammation

Endoplasmic reticulum (ER) stress may be both a trigger and consequence of chronic inflammation. Chronic inflammation is often associated with diseases that arise because of primary misfolding mutations and ER stress. Similarly, ER stress and activation of the unfolded protein response (UPR) is a feature of many chronic inflammatory and autoimmune diseases. In this review, we describe how protein misfolding and the UPR trigger inflammation, how environmental ER stressors affect antigen presenting cells and immune effector cells, and present evidence that inflammatory factors exacerbate protein misfolding and ER stress. Examples from both animal models of disease and human diseases are used to illustrate the complex interactions between ER stress and inflammation, and opportunities for therapeutic targeting are discussed. Finally, recommendations are made for future research with respect to the interaction of ER stress and inflammation.

Autoimmunity occurs when an organism develops an immune response against itself, resulting in an inflammatory reaction which damages organs such as brain, joints or pancreas. This results in diseases such as Type 1 diabetes, vasculitis, or rheumatoid arthritis. A fine balance exists in order to accommodate the control of microbial pathogens and commensals, and immune self‐tolerance. The March 2012 issue will include a review series on Autoimmune Disease, particularly featuring articles on clinical translation, and the current state of research in this area. Articles include reasons for the increased incidence of certain autoimmune diseases and allergic diseases in Western society and the advances made by the application of novel and high throughput technologies to the analysis of diseased tissues. The accompanying web focus presents links to related articles from across Nature Publishing Group.

Proteasome inhibitors improve the function of mutant lysosomal α-glucosidase in fibroblasts from Pompe disease patient carrying c.546G>T mutation

Pompe disease (glycogen storage disease type II) is an autosomal recessive myopathic disorder arising from the deficiency of lysosomal acid α-glucosidase (GAA). Recently, we found that mutant GAA in patient fibroblasts carrying c.546G>T mutation is stabilized by treatment with proteasome inhibitor as well as pharmacological chaperon N-butyl-deoxynojirimycin. In this study, we characterized the effect of two proteasome inhibitors, bortezomib and MG132, on maturation, subcellular localization and residual activity of mutant GAA in the patient fibroblasts carrying c.546G>T mutation. Each proteasome inhibitor promoted the stabilization of patient GAA and processing of them to mature forms without cytotoxic effect. Immunocytochemical analysis showed increased colocalization of GAA with the lysosomal marker LAMP2 in patient fibroblasts treated with proteasome inhibitors. Furthermore, bortezomib and MG132 also increased enzyme activity in the patient fibroblasts (about 4-fold and 2-fold, respectively). These findings indicate that proteasome inhibitor may be a novel drug as potential pharmacological chaperone therapy for Pompe disease patient carrying chaperon-responsive mutation.