Gene therapy for neurodegenerative disorders: advances, insights and prospects

Gene therapy is rapidly emerging as a powerful therapeutic strategy for a wide range of neurodegenerative disorders, including Alzheimer's disease (AD), Parkinson's disease (PD) and Huntington's disease (HD). Some early clinical trials have failed to achieve satisfactory therapeutic effects. Efforts to enhance effectiveness are now concentrating on three major fields: identification of new vectors, novel therapeutic targets, and reliable of delivery routes for transgenes. These approaches are being assessed closely in preclinical and clinical trials, which may ultimately provide powerful treatments for patients. Here, we discuss advances and challenges of gene therapy for neurodegenerative disorders, highlighting promising technologies, targets, and future prospects.

Bioactive natural compounds against human coronaviruses: a review and perspective

Coronaviruses (CoVs), a family of enveloped positive-sense RNA viruses, are characterized by club-like spikes that project from their surface, unusually large RNA genome, and unique replication capability. CoVs are known to cause various potentially lethal human respiratory infectious diseases, such as severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), and the very recent coronavirus disease 2019 (COVID-19) outbreak. Unfortunately, neither drug nor vaccine has yet been approved to date to prevent and treat these diseases caused by CoVs. Therefore, effective prevention and treatment medications against human coronavirus are in urgent need. In the past decades, many natural compounds have been reported to possess multiple biological activities, including antiviral properties. In this article, we provided a comprehensive review on the natural compounds that interfere with the life cycles of SARS and MERS, and discussed their potential use for the treatment of COVID-19.

Innate Immune Receptors, Key Actors in Cardiovascular Diseases

Cardiovascular diseases (CVDs) are the leading cause of death in the industrialized world. Most CVDs are associated with increased inflammation that arises mainly from innate immune system activation related to cardiac damage. Sustained activation of the innate immune system frequently results in maladaptive inflammatory responses that promote cardiovascular dysfunction and remodeling. Much research has focused on determining whether some mediators of the innate immune system are potential targets for CVD therapy. The innate immune system has specific receptors-termed pattern recognition receptors (PRRs)-that not only recognize pathogen-associated molecular patterns, but also sense danger-associated molecular signals. Activation of PRRs triggers the inflammatory response in different physiological systems, including the cardiovascular system. The classic PRRs, toll-like receptors (TLRs), and the more recently discovered nucleotide-binding oligomerization domain-like receptors (NLRs), have been recently proposed as key partners in the progression of several CVDs (e.g., atherosclerosis and heart failure). The present review discusses the key findings related to the involvement of TLRs and NLRs in the progression of several vascular and cardiac diseases, with a focus on whether some NLR subtypes (nucleotide-binding oligomerization domain, leucine rich repeat and pyrin domain-containing receptor 3 and nucleotide-binding oligomerization domain-containing protein 1) can be candidates for the development of new therapeutic strategies for several CVDs.

Combined alcoholic and non-alcoholic steatohepatitis

While metabolic syndrome and alcohol consumption are the two main causes of chronic liver disease, one of the two conditions is often predominant, with the other acting as a cofactor of morbimortality. It has been shown that obesity and alcohol act synergistically to increase the risk of fibrosis progression, hepatic carcinogenesis and mortality, while genetic polymorphisms can strongly influence disease progression. Based on common pathogenic pathways, there are several potential targets that could be used to treat both diseases; based on the prevalence and incidence of these diseases, new therapies and clinical trials are needed urgently.

COVID-19 for the Cardiologist: Basic Virology, Epidemiology, Cardiac Manifestations, and Potential Therapeutic Strategies

Coronavirus disease-2019 (COVID-19), a contagious disease caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), has reached pandemic status. As it spreads across the world, it has overwhelmed health care systems, strangled the global economy, and led to a devastating loss of life. Widespread efforts from regulators, clinicians, and scientists are driving a rapid expansion of knowledge of the SARS-CoV-2 virus and COVID-19. The authors review the most current data, with a focus on the basic understanding of the mechanism(s) of disease and translation to the clinical syndrome and potential therapeutics. The authors discuss the basic virology, epidemiology, clinical manifestation, multiorgan consequences, and outcomes. With a focus on cardiovascular complications, they propose several mechanisms of injury. The virology and potential mechanism of injury form the basis for a discussion of potential disease-modifying therapies.

Inhibition of NADPH oxidase alleviates germ cell apoptosis and ER stress during testicular ischemia reperfusion injury

Testicular torsion and detorsion (TTD) is a serious urological condition affecting young males that is underlined by an ischemia reperfusion injury (tIRI) to the testis as the pathophysiological mechanism. During tIRI, uncontrolled production of oxygen reactive species (ROS) causes DNA damage leading to germ cell apoptosis (GCA). The aim of the study is to explore whether inhibition of NADPH oxidase (NOX), a major source of intracellular ROS, will prevent tIRI-induced GCA and its association with endoplasmic reticulum (ER) stress. Sprague-Dawley rats (n = 36) were divided into three groups: sham, tIRI only and tIRI treated with apocynin (a NOX inhibitor). Rats undergoing tIRI endured an ischemic injury for 1 h followed by 4 h of reperfusion. Spermatogenic damage was evaluated histologically, while cellular damages were assessed using real time PCR, immunofluorescence staining, Western blot and biochemical assays. Disrupted spermatogenesis was associated with increased lipid and protein peroxidation and decreased antioxidant activity of the enzyme superoxide dismutase (SOD) as a result of tIRI. In addition, increased DNA double strand breaks and formation of 8-OHdG adducts associated with increased phosphorylation of the DNA damage response (DDR) protein H2AX. The ASK1/JNK apoptosis signaling pathway was also activated in response to tIRI. Finally, increased immuno-expression of the unfolded protein response (UPR) downstream targets: GRP78, eIF2-α1, CHOP and caspase 12 supported the presence of ER stress. Inhibition of NOX by apocynin protected against tIRI-induced GCA and ER stress. In conclusion, NOX inhibition minimized tIRI-induced intracellular oxidative damages leading to GCA and ER stress.

Direct trafficking pathways from the Golgi apparatus to the plasma membrane

In eukaryotic cells, protein sorting is a highly regulated mechanism important for many physiological events. After synthesis in the endoplasmic reticulum and trafficking to the Golgi apparatus, proteins sort to many different cellular destinations including the endolysosomal system and the extracellular space. Secreted proteins need to be delivered directly to the cell surface. Sorting of secreted proteins from the Golgi apparatus has been a topic of interest for over thirty years, yet there is still no clear understanding of the machinery that forms the post-Golgi carriers. Most evidence points to these post-Golgi carriers being tubular pleomorphic structures that bud from the trans-face of the Golgi. In this review, we present the background studies and highlight the key components of this pathway, we then discuss the machinery implicated in the formation of these carriers, their translocation across the cytosol, and their fusion at the plasma membrane.

PERK Inhibition Mitigates Restenosis and Thrombosis: A Potential Low-Thrombogenic Antirestenotic Paradigm

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Drug-eluting stents impede neointimal smooth muscle cell hyperplasia but exacerbate endothelial cell dysfunction and thrombogenicity. It has been a challenge to identify a common target to inhibit both. Findings in this study suggest PERK as such a target.

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A PERK inhibitor administered either via an endovascular (in biomimetic nanocarriers) or perivascular (in hydrogel) route effectively mitigated neointimal hyperplasia in rats.

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Oral gavage of the PERK inhibitor partially preserved the normal blood flow in a mouse model of induced thrombosis.

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Dampening PERK activity inhibited STAT3 while activating SRF in smooth muscle cells, and also reduced prothrombogenic tissue factor and growth impairment of endothelial cells.

Developing endothelial-protective, nonthrombogenic antirestenotic treatments has been a challenge. A major hurdle to this has been the identification of a common molecular target in both smooth muscle cells and endothelial cells, inhibition of which blocks dysfunction of both cell types. The authors’ findings suggest that the PERK kinase could be such a target. Importantly, PERK inhibition mitigated both restenosis and thrombosis in preclinical models, implicating a low-thrombogenic antirestenotic paradigm.

Comparison of two reducing agents dithiothreitol and tris(3-hydroxypropyl)phosphine for in vitro kinetic assay of vitamin K epoxide reductase

Vitamin K epoxide reductase (VKOR) is a target enzyme for anticoagulants, such as warfarin, that are used as medicines or rodenticides. Assessing VKOR activity is required to ensure the proper usage of these drugs. Dithiothreitol (DTT) is a typical disulfide reductant that is used as a substrate for in vitro VKOR assays. However, DTT is considered problematic because of its side effects. Tris(3-hydroxypropyl)phosphine (THP) has been found to be a reliable alternative to DTT, as shown by kinetic analyses of the VKOR with them. THP showed significantly lower V_max and K_m values than those of DTT; however, there was no significant difference in their V_max/K_m and IC₅₀ for warfarin.

TMEM16A Ca2+-activated Cl- channel inhibition ameliorates acute pancreatitis via the IP3R/Ca2+/NFκB/IL-6 signaling pathway

TMEM16A Ca²⁺-activated Cl^- channels are expressed in pancreatic acinar cells and participate in inflammation-associated diseases. Whether TMEM16A contributes to the pathogenesis of acute pancreatitis (AP) remains unknown. Here, we found that increased TMEM16A expression in the pancreatic tissue was correlated with the interleukin-6 (IL-6) level in the pancreatic tissue and in the serum of a cerulein-induced AP mouse model. IL-6 treatment promoted TMEM16A expression in AR42J pancreatic acinar cells via the IL-6 receptor (IL-6R)/signal transducers and activators of transcription 3 (STAT3) signaling pathway. In addition, TMEM16A was co-immunoprecipitated with the inositol 1,4,5-trisphosphate receptor (IP₃R) and was activated by IP₃R-mediated Ca²⁺ release. TMEM16A inhibition reduced the IP₃R-mediated Ca²⁺ release induced by cerulein. Furthermore, TMEM16A overexpression activated nuclear factor-κB (NFκB) and increased IL-6 release by increasing intracellular Ca²⁺. TMEM16A knockdown by shRNAs reduced the cerulein-induced NFκB activation by Ca²⁺. TMEM16A inhibitors inhibited NFκB activation by decreasing channel activity and reducing TMEM16A protein levels in AR42J cells, and it ameliorated pancreatic damage in cerulein-induced AP mice. This study identifies a novel mechanism underlying the pathogenesis of AP by which IL-6 promotes TMEM16A expression via IL-6R/STAT3 signaling activation, and TMEM16A overexpression increases IL-6 secretion via IP₃R/Ca²⁺/NFκB signaling activation in pancreatic acinar cells. TMEM16A inhibition may be a new potential strategy for treating AP.

Solute carrier transporters: the metabolic gatekeepers of immune cells

Solute carrier (SLC) transporters meditate many essential physiological functions, including nutrient uptake, ion influx/efflux, and waste disposal. In its protective role against tumors and infections, the mammalian immune system coordinates complex signals to support the proliferation, differentiation, and effector function of individual cell subsets. Recent research in this area has yielded surprising findings on the roles of solute carrier transporters, which were discovered to regulate lymphocyte signaling and control their differentiation, function, and fate by modulating diverse metabolic pathways and balanced levels of different metabolites. In this review, we present current information mainly on glucose transporters, amino-acid transporters, and metal ion transporters, which are critically important for mediating immune cell homeostasis in many different pathological conditions.

Novel radioligands for imaging sigma-1 receptor in brain using positron emission tomography (PET)

The sigma-1 receptor (σ₁R) is a unique intracellular protein. σ₁R plays a major role in various pathological conditions in the central nervous system (CNS), implicated in several neuropsychiatric disorders. Imaging of σ₁R in the brain using positron emission tomography (PET) could serve as a noninvasively tool for enhancing the understanding of the disease's pathophysiology. Moreover, σ₁R PET tracers can be used for target validation and quantification in diagnosis. Herein, we describe the radiosynthesis, in vivo PET/CT imaging of novel σ₁R ¹¹C-labeled radioligands based on 6-hydroxypyridazinone, [¹¹C]HCC0923 and [¹¹C]HCC0929. Two radioligands have high affinities to σ₁R, with good selectivity. In mice PET/CT imaging, both radioligands showed appropriate kinetics and distributions. Additionally, the specific interactions of two radioligands were reduced by compounds 13 and 15 (self-blocking). Of the two, [¹¹C]HCC0929 was further investigated in positive ligands blocking studies, using classic σ₁R agonist SA 4503 and σ₁R antagonist PD 144418. Both σ₁R ligands could extensively decreased the uptake of [¹¹C]HCC0929 in mice brain. Besides, the biodistribution of major brain regions and organs of mice were determined in vivo. These studies demonstrated that two radioligands, especially [¹¹C]HCC0929, possessed ideal imaging properties and might be valuable tools for non-invasive quantification of σ₁R in brain.

Cardioprotective Effects of VCP Modulator KUS121 in Murine and Porcine Models of Myocardial Infarction

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KUS121 was developed to selectively inhibit the adenosine triphosphatase activity of valosin-containing protein without affecting other cellular functions of valosin-containing protein.

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KUS121 preserved adenosine triphosphate levels, reduced endoplasmic reticulum stress, and suppressed cell death in H9C2 rat cardiomyoblast cells, treated with tunicamycin or hydrogen peroxide, or cultured in glucose-free medium.

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In murine ischemia and reperfusion injury models, KUS121 treatment after reperfusion attenuated the infarcted size and preserves cardiac function by maintaining adenosine triphosphate levels and reducing ER stress.

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In porcine ischemia and reperfusion injury models, intracoronary administration of KUS121 also attenuated the infarcted area in a dose-dependent manner.

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These results indicated that KUS121 is a promising novel therapeutic agent for myocardial infarction.

No effective treatment is yet available to reduce infarct size and improve clinical outcomes after acute myocardial infarction by enhancing early reperfusion therapy using primary percutaneous coronary intervention. The study showed that Kyoto University Substance 121 (KUS121) reduced endoplasmic reticulum stress, maintained adenosine triphosphate levels, and ameliorated the infarct size in a murine cardiac ischemia and reperfusion injury model. The study confirmed the cardioprotective effect of KUS121 in a porcine ischemia and reperfusion injury model. These findings confirmed that KUS121 is a promising novel therapeutic agent for myocardial infarction in conjunction with primary percutaneous coronary intervention.

Resveratrol derivatives increase cytosolic calcium by inhibiting plasma membrane ATPase and inducing calcium release from the endoplasmic reticulum in prostate cancer cells

Resveratrol (RES) is a putative chemotherapeutic naturally found in grapes, peanuts, and Japanese knotweed. Previous studies demonstrate that RES modulates calcium signaling as part of its chemotherapeutic activity. In this study, we determined the chemotherapeutic activity of three RES esters that have been modified at the 4' hydroxyl by the addition of pivalate, butyrate, and isobutyrate. All of the RES derivatives disrupted the calcium signaling in prostate cancer cells more than the parent compound, RES. Further, we demonstrate that the RES derivatives may disrupt the calcium homeostasis by activating calcium release from the endoplasmic reticulum and inhibiting plasma membrane Ca²⁺-ATPase. The pivalated and butyrated RES derivatives decreased cell viability significantly more than RES. Because pivalated and butyrated RES are more effective than RES at targeting calcium signaling pathways, pivalated and butyrated RES may serve as more effective chemotherapeutics.

Off the wall: The rhyme and reason of Neurospora crassa hyphal morphogenesis

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Chitin and β-1,3-glucan synthases are transported separately in chitosomes and macrovesicles.

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Chitin synthases occupy the core of the SPK; β-1,3-glucan synthases the outer layer.

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CHS-4 arrival to the SPK and septa is CSE-7 dependent.

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Rabs YPT-1 and YPT-31 localization at the SPK mimics that of chitosomes and macrovesicles.

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The exocyst acts as a tether between the SPK outer layer vesicles and the apical PM.

The fungal cell wall building processes are the ultimate determinants of hyphal shape. In Neurospora crassa the main cell wall components, β-1,3-glucan and chitin, are synthesized by enzymes conveyed by specialized vesicles to the hyphal tip. These vesicles follow different secretory routes, which are delicately coordinated by cargo-specific Rab GTPases until their accumulation at the Spitzenkörper. From there, the exocyst mediates the docking of secretory vesicles to the plasma membrane, where they ultimately get fused. Although significant progress has been done on the cellular mechanisms that carry cell wall synthesizing enzymes from the endoplasmic reticulum to hyphal tips, a lot of information is still missing. Here, the current knowledge on N. crassa cell wall composition and biosynthesis is presented with an emphasis on the underlying molecular and cellular secretory processes.

Identification of the evolutionarily conserved nuclear envelope proteins Lem2 and MicLem2 in Tetrahymena thermophila

Lem2 family proteins, i.e. the LAP2-Emerin-MAN1 (LEM) domain-containing nuclear envelope proteins, are well-conserved from yeasts to humans, both of which belong to the Opisthokonta supergroup. However, whether their homologs are present in other eukaryotic phylogenies remains unclear. In this study, we identified two Lem2 homolog proteins, which we named as Lem2 and MicLem2, in a ciliate Tetrahymena thermophila belonging to the SAR supergroup. Lem2 was localized to the nuclear envelope of the macronucleus (MAC) and micronucleus (MIC), while MicLem2 was exclusively localized to the nuclear envelope of the MIC. Immunoelectron microscopy revealed that Lem2 in T. thermophila was localized to both the inner and outer nuclear envelopes of the MAC and MIC, while MicLem2 was mostly localized to the nuclear pores of the MIC. Molecular domain analysis using GFP-fused protein showed that the N-terminal and luminal domains, including the transmembrane segments, are responsible for nuclear envelope localization. During sexual reproduction, enrichment of Lem2 occurred in the nuclear envelopes of the MAC and MIC to be degraded, while MicLem2 was enriched in the nuclear envelope of the MIC that escaped degradation. These findings suggest the unique characteristics of Tetrahymena Lem2 proteins. Our findings provide insight into the evolutionary divergence of nuclear envelope proteins.

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Conserved nuclear envelope proteins Lem2 and MicLem2 are identified in Tetrahymena.

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Lem2 is localized to the nuclear envelope of the macronucleus and the micronucleus.

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MicLem2 is localized to the nuclear pore complex of the micronucleus.

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In sexual reproduction, Lem2 is enriched to the nuclei assigned to degradation.

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MicLem2 is enriched to the micronuclei that are escaped from degradation.

Effects of repetitive transcranial magnetic stimulation on ER stress-related genes and glutamate, γ-aminobutyric acid and glycine transporter genes in mouse brain

Repetitive transcranial magnetic stimulation (rTMS) is an emerging therapy for the treatment of psychiatric disorders. However, the mechanisms underlying the therapeutic effects of rTMS are still unclear, limiting its optimisation. Lasting effects suggest changes in disease-related genes, so we conducted gene chip and qRT-PCR analyses of genes associated with psychiatric diseases in the mouse brain at various times following 1, 20, 30 or 40 days of rTMS. Many genes were differentially expressed in the rTMS-treated mouse brain compared to sham controls, including genes encoding neurotransmitter transporters (upregulation of EAAT4, GLAST, GLT-1, GAT2, GAT4, GLYT1 and GLYT2), and endoplasmic reticulum (ER)-stress proteins (downregulation of IRE1α, IRE1β, and XBP1, upregulation of ATF6 and GRP78/Bip). Expression changes in many of these genes were also observed 10 days after the last rTMS treatment. In PC12 cells, rTMS upregulated GRP78/Bip mRNA and enhanced resistance against H₂O₂ stress. These results suggest that rTMS differentially modulates multiple genes associated with psychiatric and neurodegenerative disorders. Sustained changes in the expression of these genes may underlie the therapeutic efficacy of chronic rTMS.

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Gene expression changes in mouse brain were examined following rTMS.

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rTMS altered expression of ER-stress and neurotransmitter transporter genes.

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rTMS also induced ER-stress genes in PC12 cells and protected against H₂O₂ toxicity.

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These expression changes may underlie the therapeutic benefits of rTMS.

Experimental Nonalcoholic Steatohepatitis and Liver Fibrosis Are Ameliorated by Pharmacologic Activation of Nrf2 (NF-E2 p45-Related Factor 2)

BACKGROUND & AIMS

Nonalcoholic steatohepatitis (NASH) is associated with oxidative stress. We surmised that pharmacologic activation of NF-E2 p45-related factor 2 (Nrf2) using the acetylenic tricyclic bis(cyano enone) TBE-31 would suppress NASH because Nrf2 is a transcriptional master regulator of intracellular redox homeostasis.

METHODS

Nrf2+/+ and Nrf2-/- C57BL/6 mice were fed a high-fat plus fructose (HFFr) or regular chow diet for 16 weeks or 30 weeks, and then treated for the final 6 weeks, while still being fed the same HFFr or regular chow diets, with either TBE-31 or dimethyl sulfoxide vehicle control. Measures of whole-body glucose homeostasis, histologic assessment of liver, and biochemical and molecular measurements of steatosis, endoplasmic reticulum (ER) stress, inflammation, apoptosis, fibrosis, and oxidative stress were performed in livers from these animals.

RESULTS

TBE-31 treatment reversed insulin resistance in HFFr-fed wild-type mice, but not in HFFr-fed Nrf2-null mice. TBE-31 treatment of HFFr-fed wild-type mice substantially decreased liver steatosis and expression of lipid synthesis genes, while increasing hepatic expression of fatty acid oxidation and lipoprotein assembly genes. Also, TBE-31 treatment decreased ER stress, expression of inflammation genes, and markers of apoptosis, fibrosis, and oxidative stress in the livers of HFFr-fed wild-type mice. By comparison, TBE-31 did not decrease steatosis, ER stress, lipogenesis, inflammation, fibrosis, or oxidative stress in livers of HFFr-fed Nrf2-null mice.

CONCLUSIONS

Pharmacologic activation of Nrf2 in mice that had already been rendered obese and insulin resistant reversed insulin resistance, suppressed hepatic steatosis, and mitigated against NASH and liver fibrosis, effects that we principally attribute to inhibition of ER, inflammatory, and oxidative stress.

Ethanol Induced Disordering of Pancreatic Acinar Cell Endoplasmic Reticulum: An ER Stress/Defective Unfolded Protein Response Model

BACKGROUND & AIMS

Heavy alcohol drinking is associated with pancreatitis, whereas moderate intake lowers the risk. Mice fed ethanol long term show no pancreas damage unless adaptive/protective responses mediating proteostasis are disrupted. Pancreatic acini synthesize digestive enzymes (largely serine hydrolases) in the endoplasmic reticulum (ER), where perturbations (eg, alcohol consumption) activate adaptive unfolded protein responses orchestrated by spliced X-box binding protein 1 (XBP1). Here, we examined ethanol-induced early structural changes in pancreatic ER proteins.

METHODS

Wild-type and Xbp1+/- mice were fed control and ethanol diets, then tissues were homogenized and fractionated. ER proteins were labeled with a cysteine-reactive probe, isotope-coded affinity tag to obtain a novel pancreatic redox ER proteome. Specific labeling of active serine hydrolases in ER with fluorophosphonate desthiobiotin also was characterized proteomically. Protein structural perturbation by redox changes was evaluated further in molecular dynamic simulations.

RESULTS

Ethanol feeding and Xbp1 genetic inhibition altered ER redox balance and destabilized key proteins. Proteomic data and molecular dynamic simulations of Carboxyl ester lipase (Cel), a unique serine hydrolase active within ER, showed an uncoupled disulfide bond involving Cel Cys266, Cel dimerization, ER retention, and complex formation in ethanol-fed, XBP1-deficient mice.

CONCLUSIONS

Results documented in ethanol-fed mice lacking sufficient spliced XBP1 illustrate consequences of ER stress extended by preventing unfolded protein response from fully restoring pancreatic acinar cell proteostasis during ethanol-induced redox challenge. In this model, orderly protein folding and transport to the secretory pathway were disrupted, and abundant molecules including Cel with perturbed structures were retained in ER, promoting ER stress-related pancreas pathology.

Pancreatic HIF2α Stabilization Leads to Chronic Pancreatitis and Predisposes to Mucinous Cystic Neoplasm

BACKGROUND & AIMS

Tissue hypoxia controls cell differentiation in the embryonic pancreas, and promotes tumor growth in pancreatic cancer. The cellular response to hypoxia is controlled by the hypoxia-inducible factor (HIF) proteins, including HIF2α. Previous studies of HIF action in the pancreas have relied on loss-of-function mouse models, and the effects of HIF2α expression in the pancreas have remained undefined.

METHODS

We developed several transgenic mouse models based on the expression of an oxygen-stable form of HIF2α, or indirect stabilization of HIF proteins though deletion of von Hippel-Lindau, thus preventing HIF degradation. Furthermore, we crossed both sets of animals into mice expressing oncogenic KrasG12D in the pancreas.

RESULTS

We show that HIF2α is not expressed in the normal human pancreas, however, it is up-regulated in human chronic pancreatitis. Deletion of von Hippel-Lindau or stabilization of HIF2α in mouse pancreata led to the development of chronic pancreatitis. Importantly, pancreatic HIF1α stabilization did not disrupt the pancreatic parenchyma, indicating that the chronic pancreatitis phenotype is specific to HIF2α. In the presence of oncogenic Kras, HIF2α stabilization drove the formation of cysts resembling mucinous cystic neoplasm (MCN) in humans. Mechanistically, we show that the pancreatitis phenotype is linked to expression of multiple inflammatory cytokines and activation of the unfolded protein response. Conversely, MCN formation is linked to activation of Wnt signaling, a feature of human MCN.

CONCLUSIONS

We show that pancreatic HIF2α stabilization disrupts pancreatic homeostasis, leading to chronic pancreatitis, and, in the context of oncogenic Kras, MCN formation. These findings provide new mouse models of both chronic pancreatitis and MCN, as well as illustrate the importance of hypoxia signaling in the pancreas.

Reduction of calcium flux from the extracellular region and endoplasmic reticulum by amorphous nano-silica particles owing to carboxy group addition on their surface

Several studies have reported that amorphous nano-silica particles (nano-SPs) modulate calcium flux, although the mechanism remains incompletely understood. We thus analyzed the relationship between calcium flux and particle surface properties and determined the calcium flux route. Treatment of Balb/c 3T3 fibroblasts with nano-SPs with a diameter of 70 nm (nSP70) increased cytosolic calcium concentration, but that with SPs with a diameter of 300 or 1000 nm did not. Surface modification of nSP70 with a carboxy group also did not modulate calcium flux. Pretreatment with a general calcium entry blocker almost completely suppressed calcium flux by nSP70. Preconditioning by emptying the endoplasmic reticulum (ER) calcium stores slightly suppressed calcium flux by nSP70. These results indicate that nSP70 mainly modulates calcium flux across plasma membrane calcium channels, with subsequent activation of the ER calcium pump, and that the potential of calcium flux by nano-SPs is determined by the particle surface charge.

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Nano-silica particles increased cytosolic calcium flux in fibroblasts.

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Calcium flux by nano-SPs was suppressed by SKF96365 and thapsigargin.

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Calcium flux modulation by nano-SPs was determined by their surface structure.

Pentylenetetrazol modulates redox system by inducing addicsin translocation from endoplasmic reticulum to plasma membrane in NG108-15 cells

Addicsin (Arl6ip5) is a multifunctional physiological and pathophysiological regulator that exerts its effects by readily forming homo- and hetero-complexes with various functional factors. In particular, addicsin acts as a negative modulator of neural glutamate transporter excitatory amino acid carrier 1 (EAAC1) and participates in the regulation of intracellular glutathione (GSH) content by negatively modulating EAAC1-mediated cysteine and glutamate uptake. Addicsin is considered to play a crucial role in the onset of neurodegenerative diseases including epilepsy. However, the molecular dynamics of addicsin remains largely unknown. Here, we report the dynamics of addicsin in NG108-15 cells upon exposure to pentylenetetrazol (PTZ), a representative epileptogenic agent acting on the gamma-Aminobutyric acid A (GABA_A) receptor. Fluorescent immunostaining analysis demonstrated that addicsin drastically changed its localization from the endoplasmic reticulum (ER) to the plasma membrane within 1 h of PTZ exposure in a dose-dependent manner. Moreover, addicsin was co-localized with the plasma membrane markers EAAC1 and Na⁺/K⁺ ATPase alpha-3 upon PTZ stimulation. This translocation was significantly inhibited by a non-competitive GABA_A receptor antagonist, picrotoxin, but not by a competitive GABA_A receptor antagonist, bicuculline. Furthermore, lactate dehydrogenase (LDH) assay and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assay showed that PTZ-induced addicsin translocation was accompanied by a decrease of radical-scavenging activity and an increase of cytotoxicity in a PTZ dose-dependent manner. These findings suggest that PTZ induces the translocation of addicsin from the ER to the plasma membrane and modulates the redox system by regulating EAAC1-mediated GSH synthesis, which leads to the activation of cell death signaling.

Endoplasmic reticulum stress and eIF2α phosphorylation: The Achilles heel of pancreatic β cells

BACKGROUND

Pancreatic β cell dysfunction and death are central in the pathogenesis of most if not all forms of diabetes. Understanding the molecular mechanisms underlying β cell failure is important to develop β cell protective approaches.

SCOPE OF REVIEW

Here we review the role of endoplasmic reticulum stress and dysregulated endoplasmic reticulum stress signaling in β cell failure in monogenic and polygenic forms of diabetes. There is substantial evidence for the presence of endoplasmic reticulum stress in β cells in type 1 and type 2 diabetes. Direct evidence for the importance of this stress response is provided by an increasing number of monogenic forms of diabetes. In particular, mutations in the PERK branch of the unfolded protein response provide insight into its importance for human β cell function and survival. The knowledge gained from different rodent models is reviewed. More disease- and patient-relevant models, using human induced pluripotent stem cells differentiated into β cells, will further advance our understanding of pathogenic mechanisms. Finally, we review the therapeutic modulation of endoplasmic reticulum stress and signaling in β cells.

MAJOR CONCLUSIONS

Pancreatic β cells are sensitive to excessive endoplasmic reticulum stress and dysregulated eIF2α phosphorylation, as indicated by transcriptome data, monogenic forms of diabetes and pharmacological studies. This should be taken into consideration when devising new therapeutic approaches for diabetes.

The Munich MIDY Pig Biobank - A unique resource for studying organ crosstalk in diabetes

OBJECTIVE

The prevalence of diabetes mellitus and associated complications is steadily increasing. As a resource for studying systemic consequences of chronic insulin insufficiency and hyperglycemia, we established a comprehensive biobank of long-term diabetic INSC94Y transgenic pigs, a model of mutant INS gene-induced diabetes of youth (MIDY), and of wild-type (WT) littermates.

METHODS

Female MIDY pigs (n = 4) were maintained with suboptimal insulin treatment for 2 years, together with female WT littermates (n = 5). Plasma insulin, C-peptide and glucagon levels were regularly determined using specific immunoassays. In addition, clinical chemical, targeted metabolomics, and lipidomics analyses were performed. At age 2 years, all pigs were euthanized, necropsied, and a broad spectrum of tissues was taken by systematic uniform random sampling procedures. Total beta cell volume was determined by stereological methods. A pilot proteome analysis of pancreas, liver, and kidney cortex was performed by label free proteomics.

RESULTS

MIDY pigs had elevated fasting plasma glucose and fructosamine concentrations, C-peptide levels that decreased with age and were undetectable at 2 years, and an 82% reduced total beta cell volume compared to WT. Plasma glucagon and beta hydroxybutyrate levels of MIDY pigs were chronically elevated, reflecting hallmarks of poorly controlled diabetes in humans. In total, ∼1900 samples of different body fluids (blood, serum, plasma, urine, cerebrospinal fluid, and synovial fluid) as well as ∼17,000 samples from ∼50 different tissues and organs were preserved to facilitate a plethora of morphological and molecular analyses. Principal component analyses of plasma targeted metabolomics and lipidomics data and of proteome profiles from pancreas, liver, and kidney cortex clearly separated MIDY and WT samples.

CONCLUSIONS

The broad spectrum of well-defined biosamples in the Munich MIDY Pig Biobank that will be available to the scientific community provides a unique resource for systematic studies of organ crosstalk in diabetes in a multi-organ, multi-omics dimension.