The Identification of a Novel Calcium-Dependent Link Between NAD+ and Glucose Deprivation-Induced Increases in Protein O-GlcNAcylation and ER Stress

The modification of proteins by O-linked β-N-acetylglucosamine (O-GlcNAc) is associated with the regulation of numerous cellular processes. Despite the importance of O-GlcNAc in mediating cellular function our understanding of the mechanisms that regulate O-GlcNAc levels is limited. One factor known to regulate protein O-GlcNAc levels is nutrient availability; however, the fact that nutrient deficient states such as ischemia increase O-GlcNAc levels suggests that other factors also contribute to regulating O-GlcNAc levels. We have previously reported that in unstressed cardiomyocytes exogenous NAD+ resulted in a time and dose dependent decrease in O-GlcNAc levels. Therefore, we postulated that NAD+ and cellular O-GlcNAc levels may be coordinately regulated. Using glucose deprivation as a model system in an immortalized human ventricular cell line, we examined the influence of extracellular NAD+ on cellular O-GlcNAc levels and ER stress in the presence and absence of glucose. We found that NAD+ completely blocked the increase in O-GlcNAc induced by glucose deprivation and suppressed the activation of ER stress. The NAD+ metabolite cyclic ADP-ribose (cADPR) had similar effects on O-GlcNAc and ER stress suggesting a common underlying mechanism. cADPR is a ryanodine receptor (RyR) agonist and like caffeine, which also activates the RyR, both mimicked the effects of NAD+. SERCA inhibition, which also reduces ER/SR Ca2+ levels had similar effects to both NAD+ and cADPR on O-GlcNAc and ER stress responses to glucose deprivation. The observation that NAD+, cADPR, and caffeine all attenuated the increase in O-GlcNAc and ER stress in response to glucose deprivation, suggests a potential common mechanism, linked to ER/SR Ca2+ levels, underlying their activation. Moreover, we showed that TRPM2, a plasma membrane cation channel was necessary for the cellular responses to glucose deprivation. Collectively, these findings support a novel Ca2+-dependent mechanism underlying glucose deprivation induced increase in O-GlcNAc and ER stress.

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Transglutaminase 2 Induces Deficits in Social Behavior in Mice

Neural Plasticity ◽

10.1155/2018/2019091 ◽

2018 ◽

Vol 2018 ◽

pp. 1-9 ◽

Cited By ~ 1

Author(s):

Amanda Crider ◽

Talisha Davis ◽

Anthony O. Ahmed ◽

Lin Mei ◽

Anilkumar Pillai

Keyword(s):

Social Behavior ◽

Er Stress ◽

Transglutaminase 2 ◽

Underlying Mechanism ◽

Autism Spectrum ◽

Postmortem Brain ◽

Postmortem Human Brain ◽

Calcium Dependent ◽

Human Postmortem Brain ◽

Protein Levels

Impairments in social behavior are highly implicated in many neuropsychiatric disorders. Recent studies indicate a role for endoplasmic reticulum (ER) stress in altering social behavior, but the underlying mechanism is not known. In the present study, we examined the role of transglutaminase 2 (TG2), a calcium-dependent enzyme known to be induced following ER stress, in social behavior in mice. ER stress induced by tunicamycin administration increased TG2 protein levels in the mouse prefrontal cortex (PFC). PFC-specific inhibition of TG2 attenuated ER stress-induced deficits in social behavior. Conversely, overexpression of TG2 in the PFC resulted in social behavior impairments in mice. In addition, systemic administration of cysteamine, a TG2 inhibitor, attenuated social behavior deficits. Our preliminary findings using postmortem human brain samples found increases in TG2 mRNA and protein levels in the middle frontal gyrus of subjects with autism spectrum disorder. These findings in mice and human postmortem brain samples identify changes in TG2 activity in the possible dysregulation of social behavior.

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Arginine Decarboxylase Is Essential for Pneumococcal Stress Responses

Pathogens ◽

10.3390/pathogens10030286 ◽

2021 ◽

Vol 10 (3) ◽

pp. 286

Author(s):

Mary Frances Nakamya ◽

Moses B. Ayoola ◽

Leslie A. Shack ◽

Mirghani Mohamed ◽

Edwin Swiatlo ◽

...

Keyword(s):

Stress Responses ◽

Critical Role ◽

Acid Stress ◽

Arginine Decarboxylase ◽

Arginine Deiminase ◽

Dependent Manner ◽

Cellular Processes ◽

Opportunistic Human Pathogen ◽

Thiol Peroxidase ◽

The Impact

Polyamines such as putrescine, cadaverine, and spermidine are small cationic molecules that play significant roles in cellular processes, including bacterial stress responses and host–pathogen interactions. Streptococcus pneumoniae is an opportunistic human pathogen, which causes several diseases that account for significant morbidity and mortality worldwide. As it transits through different host niches, S. pneumoniae is exposed to and must adapt to different types of stress in the host microenvironment. We earlier reported that S. pneumoniae TIGR4, which harbors an isogenic deletion of an arginine decarboxylase (ΔspeA), an enzyme that catalyzes the synthesis of agmatine in the polyamine synthesis pathway, has a reduced capsule. Here, we report the impact of arginine decarboxylase deletion on pneumococcal stress responses. Our results show that ΔspeA is more susceptible to oxidative, nitrosative, and acid stress compared to the wild-type strain. Gene expression analysis by qRT-PCR indicates that thiol peroxidase, a scavenger of reactive oxygen species and aguA from the arginine deiminase system, could be important for peroxide stress responses in a polyamine-dependent manner. Our results also show that speA is essential for endogenous hydrogen peroxide and glutathione production in S. pneumoniae. Taken together, our findings demonstrate the critical role of arginine decarboxylase in pneumococcal stress responses that could impact adaptation and survival in the host.

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Crosstalk between endoplasmic reticulum stress and oxidative stress: a dynamic duo in multiple myeloma

Cellular and Molecular Life Sciences ◽

10.1007/s00018-021-03756-3 ◽

2021 ◽

Author(s):

Sinan Xiong ◽

Wee-Joo Chng ◽

Jianbiao Zhou

Keyword(s):

Oxidative Stress ◽

Multiple Myeloma ◽

Endoplasmic Reticulum ◽

Er Stress ◽

Cell Fate ◽

Stress Responses ◽

Plasma Cells ◽

Reactive Oxygen Species Generation ◽

Future Research ◽

And Oxidative Stress

AbstractUnder physiological and pathological conditions, cells activate the unfolded protein response (UPR) to deal with the accumulation of unfolded or misfolded proteins in the endoplasmic reticulum. Multiple myeloma (MM) is a hematological malignancy arising from immunoglobulin-secreting plasma cells. MM cells are subject to continual ER stress and highly dependent on the UPR signaling activation due to overproduction of paraproteins. Mounting evidence suggests the close linkage between ER stress and oxidative stress, demonstrated by overlapping signaling pathways and inter-organelle communication pivotal to cell fate decision. Imbalance of intracellular homeostasis can lead to deranged control of cellular functions and engage apoptosis due to mutual activation between ER stress and reactive oxygen species generation through a self-perpetuating cycle. Here, we present accumulating evidence showing the interactive roles of redox homeostasis and proteostasis in MM pathogenesis and drug resistance, which would be helpful in elucidating the still underdefined molecular pathways linking ER stress and oxidative stress in MM. Lastly, we highlight future research directions in the development of anti-myeloma therapy, focusing particularly on targeting redox signaling and ER stress responses.

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Argininosuccinate synthase 1 suppresses tumor progression through activation of PERK/eIF2α/ATF4/CHOP axis in hepatocellular carcinoma

Journal of Experimental & Clinical Cancer Research ◽

10.1186/s13046-021-01912-y ◽

2021 ◽

Vol 40 (1) ◽

Author(s):

Sanghwa Kim ◽

Minji Lee ◽

Yeonhwa Song ◽

Su-Yeon Lee ◽

Inhee Choi ◽

...

Keyword(s):

Hepatocellular Carcinoma ◽

Liver Cancer ◽

Er Stress ◽

Stress Responses ◽

Arginine Metabolism ◽

Tumor Spheroids ◽

Clinical Value ◽

Suppressor Activity ◽

Argininosuccinate Synthase ◽

Hcc Cells

Abstract Background Hepatocellular carcinoma (HCC) is one of the most common malignant cancers worldwide, and liver cancer has increased in mortality due to liver cancer because it was detected at an advanced stages in patients with liver dysfunction, making HCC a lethal cancer. Accordingly, we aim to new targets for HCC drug discovery using HCC tumor spheroids. Methods Our comparative proteomic analysis of HCC cells grown in culture as monolayers (2D) and spheroids (3D) revealed that argininosuccinate synthase 1 (ASS1) expression was higher in 3D cells than in 2D cells due to upregulated endoplasmic reticulum (ER) stress responses. We investigated the clinical value of ASS1 in Korean patients with HCC. The mechanism underlying ASS1-mediated tumor suppression was investigated in HCC spheroids. ASS1-mediated improvement of chemotherapy efficiency was observed using high content screening in an HCC xenograft mouse model. Results Studies of tumor tissue from Korean HCC patients showed that, although ASS1 expression was low in most samples, high levels of ASS1 were associated with favorable overall survival of patients. Here, we found that bidirectional interactions between ASS1 ER stress responses in HCC-derived multicellular tumor spheroids can limit HCC progression. ASS1 overexpression effectively inhibited tumor growth and enhanced the efficacy of in vitro and in vivo anti-HCC combination chemotherapy via activation of the PERK/eIF2α/ATF4/CHOP axis, but was not dependent on the status of p53 and arginine metabolism. Conclusions These results demonstrate the critical functional roles for the arginine metabolism–independent tumor suppressor activity of ASS1 in HCC and suggest that upregulating ASS1 in these tumors is a potential strategy in HCC cells with low ASS1 expression.

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NIK promotes metabolic adaptation of glioblastoma cells to bioenergetic stress

Cell Death and Disease ◽

10.1038/s41419-020-03383-z ◽

2021 ◽

Vol 12 (3) ◽

Author(s):

Michael L. Kamradt ◽

Ji-Ung Jung ◽

Kathryn M. Pflug ◽

Dong W. Lee ◽

Victor Fanniel ◽

...

Keyword(s):

Stress Responses ◽

Glucose Deprivation ◽

Metabolic Adaptation ◽

Mitochondrial Morphology ◽

Atp Production ◽

Tumor Microenvironments ◽

Iκb Kinase ◽

Critical Measure

AbstractCancers, including glioblastoma multiforme (GBM), undergo coordinated reprogramming of metabolic pathways that control glycolysis and oxidative phosphorylation (OXPHOS) to promote tumor growth in diverse tumor microenvironments. Adaptation to limited nutrient availability in the microenvironment is associated with remodeling of mitochondrial morphology and bioenergetic capacity. We recently demonstrated that NF-κB-inducing kinase (NIK) regulates mitochondrial morphology to promote GBM cell invasion. Here, we show that NIK is recruited to the outer membrane of dividing mitochondria with the master fission regulator, Dynamin-related protein1 (DRP1). Moreover, glucose deprivation-mediated metabolic shift to OXPHOS increases fission and mitochondrial localization of both NIK and DRP1. NIK deficiency results in decreased mitochondrial respiration, ATP production, and spare respiratory capacity (SRC), a critical measure of mitochondrial fitness. Although IκB kinase α and β (IKKα/β) and NIK are required for OXPHOS in high glucose media, only NIK is required to increase SRC under glucose deprivation. Consistent with an IKK-independent role for NIK in regulating metabolism, we show that NIK phosphorylates DRP1-S616 in vitro and in vivo. Notably, a constitutively active DRP1-S616E mutant rescues oxidative metabolism, invasiveness, and tumorigenic potential in NIK−/− cells without inducing IKK. Thus, we establish that NIK is critical for bioenergetic stress responses to promote GBM cell pathogenesis independently of IKK. Our data suggest that targeting NIK may be used to exploit metabolic vulnerabilities and improve therapeutic strategies for GBM.

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MondoA Drives B-ALL Malignancy through Enhanced Adaptation to Metabolic Stress

Blood ◽

10.1182/blood.2020007932 ◽

2021 ◽

Author(s):

Alexandra Sipol ◽

Erik Hameister ◽

Busheng Xue ◽

Julia Hofstetter ◽

Maxim Barenboim ◽

...

Keyword(s):

Stress Responses ◽

Lymphoblastic Leukemia ◽

Metabolic Stress ◽

Tca Cycle ◽

Underlying Mechanism ◽

Patient Data ◽

Data Sets ◽

Dependent Manner

Cancer cells are in most instances characterized by rapid proliferation and uncontrolled cell division. Hence, they must adapt to proliferation-induced metabolic stress through intrinsic or acquired anti-metabolic stress responses to maintain homeostasis and survival. One mechanism to achieve this is to reprogram gene expression in a metabolism-dependent manner. MondoA (also known as MLXIP), a member of the MYC interactome, has been described as an example of such a metabolic sensor. However, the role of MondoA in malignancy is not fully understood and the underlying mechanism in metabolic responses remains elusive. By assessing patient data sets we found that MondoA overexpression is associated with a worse survival in pediatric common acute lymphoblastic leukemia (B-ALL). Using CRISPR/Cas9 and RNA interference approaches, we observed that MondoA depletion reduces transformational capacity of B-ALL cells in vitro and dramatically inhibits malignant potential in an in vivo mouse model. Interestingly, reduced expression of MondoA in patient data sets correlated with enrichment in metabolic pathways. The loss of MondoA correlated with increased tricarboxylic acid (TCA) cycle activity. Mechanistically, MondoA senses metabolic stress in B-ALL cells by restricting oxidative phosphorylation through reduced PDH activity. Glutamine starvation conditions greatly enhance this effect and highlight the inability to mitigate metabolic stress upon loss of MondoA in B-ALL. Our findings give a novel insight into the function of MondoA in pediatric B-ALL and support the notion that MondoA inhibition in this entity offers a therapeutic opportunity and should be further explored.

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Acute high-intensity aerobic exercise increases gene expression of calcium-related proteins and activates endoplasmic reticulum stress responses in diabetic hearts

Comparative Exercise Physiology ◽

10.3920/cep200022 ◽

2020 ◽

pp. 1-14

Author(s):

H.O. Ness ◽

K. Ljones ◽

M. Pinho ◽

M.A. Høydal

Keyword(s):

Gene Expression ◽

Exercise Training ◽

Er Stress ◽

Aerobic Exercise ◽

Stress Responses ◽

Mitochondrial Respiration ◽

High Intensity ◽

Acute Exercise ◽

Contractile Function ◽

Aerobic Exercise Training

Regular aerobic exercise training has a wide range of beneficial cardiac effects, but recent data also show that acute very strenuous aerobic exercise may impose a transient cardiac exhaustion. The aim of this study was to assess the response to acute high-intensity aerobic exercise on properties of mitochondrial respiration, cardiomyocyte contractile function, Ca2+ handling and transcriptional changes for key proteins facilitating Ca2+ handling and endoplasmic reticulum (ER) stress responses in type 2 diabetic mice. Diabetic mice were assigned to either sedentary control or an acute bout of exercise, consisting of a 10×4 minutes high-intensity interval treadmill run. Mitochondrial respiration, contractile and Ca2+ handling properties of cardiomyocytes were analysed 1 hour after completion of exercise. Gene expression levels of key Ca2+ handling and ER stress response proteins were measured in cardiac tissue samples harvested 1 hour and 24 hours after exercise. We found no significant changes in mitochondrial respiration, cardiomyocyte contractile function or Ca2+ handling 1 hour after the acute exercise. However, gene expression of Atp2a2, Slc8a1 and Ryr2, encoding proteins involved in cardiomyocyte Ca2+ handling, were all significantly upregulated 24 hours after the acute exercise bout. Acute exercise also altered gene expression of several key proteins in ER stress response and unfolded protein response, including Grp94, total Xbp1, Gadd34, and Atf6. The present results show that despite no significant alterations in functional properties of cardiomyocyte function, Ca2+ handling or mitochondrial respiration following one bout of high intensity aerobic exercise training, the expression of genes involved in Ca2+ handling and key components in ER stress and the unfolded protein response were changed. These transcriptional changes may constitute important steps in initiating adaptive remodelling to exercise training in type 2 diabetes.

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Combination of isoflurane and propofol, a means for general anesthesia in the orthopedic surgery of perioperative cerebral hypoperfusion rats to avoid cognitive impairment Anesthesia of perioperative cerebral hypoperfusion

10.21203/rs.2.14325/v4 ◽

2020 ◽

Author(s):

Xinyue Bu ◽

Tang Li ◽

Haiyun Wang ◽

Zhengyuan Xia ◽

Di Guo ◽

...

Keyword(s):

Cognitive Impairment ◽

Cognitive Function ◽

Er Stress ◽

General Anesthesia ◽

Underlying Mechanism ◽

Cerebral Hypoperfusion ◽

Nissl Staining ◽

Aging Rats ◽

Biochemical Analyses ◽

Common Carotid Arteries

Abstract Background: Perioperative cerebral hypoperfusion often occurs. However, the underlying mechanism of cognitive impairment resulting when perioperative cerebral hypoperfusion occurs remain mostly to be determined. Anesthetic isoflurane induces neuronal injury via endoplasmic reticulum (ER) stress, whereas sub-anesthetic dose of propofol improves postoperative cognitive function. However, the effects of the combination of isoflurane plus propofol, which is a common combination of anesthesia for patient, on ER stress and the associated cognitive function remain unknown. Methods: We therefore set out to determine the effects of isoflurane plus propofol on the ER stress and cognitive function in the rats insulted by cerebral hypoperfusion. A ligation of bilateral common carotid arteries (CCA) surgery was adopted to prepare rats as cerebral hypoperfusion (CH) animal model. A second surgery, open reduction and internal fixation (ORIF), requiring general anesthesia, was operated 30 days later so that the effects of anesthetics on cognitive function of these CH rats could be assessed. The rats received isoflurane alone (1.9%), propofol alone (40 mg·kg -1 ·h -1 ) or a combination of isoflurane and propofol (1% and 20 mg·kg -1 ·h -1 or 1.4% and 10 mg·kg -1 ·h -1 ). Behavior studies (Fear Conditioning test), histological analyses (Nissl staining) and biochemical analyses (western blotting for the harvested rat brain tissues) were employed in the studies. Results: We found that the combination of 1% isoflurane plus 20 mg·kg -1 ·h -1 propol did not aggravate the cognitive impairment and the ER stress in aging rats with cerebral hypoperusion and being subjected to an ORIF surgery. Conclusions: These data suggest that ER stress contributes to the underlying mechanism of cognitive impairment and the combination of isoflurane and propofol did not aggravate the cognitive impairment and the ER stress in aging rats with cerebral hypoperfusion and being subjected to an ORIF surgery.

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Selective Activation of Endoplasmic Reticulum Stress by Reactive-Oxygen-Species-Mediated Ochratoxin A-Induced Apoptosis in Tubular Epithelial Cells

International Journal of Molecular Sciences ◽

10.3390/ijms222010951 ◽

2021 ◽

Vol 22 (20) ◽

pp. 10951

Author(s):

Chong-Sun Khoi ◽

Yu-Wen Lin ◽

Jia-Huang Chen ◽

Biing-Hui Liu ◽

Tzu-Yu Lin ◽

...

Keyword(s):

Reactive Oxygen Species ◽

Endoplasmic Reticulum ◽

Er Stress ◽

Ochratoxin A ◽

Reactive Oxygen ◽

Underlying Mechanism ◽

Oxygen Species ◽

Food And Feed ◽

Renal Proximal Tubular Cells ◽

Induced Apoptosis

Ochratoxin A (OTA), one of the major food-borne mycotoxins, impacts the health of humans and livestock by contaminating food and feed. However, the underlying mechanism of OTA nephrotoxicity remains unknown. This study demonstrated that OTA induced apoptosis through selective endoplasmic reticulum (ER) stress activation in human renal proximal tubular cells (HK-2). OTA increased ER-stress-related JNK and precursor caspase-4 cleavage apoptotic pathways. Further study revealed that OTA increased reactive oxygen species (ROS) levels, and N-acetyl cysteine (NAC) could reduce OTA-induced JNK-related apoptosis and ROS levels in HK-2 cells. Our results demonstrate that OTA induced ER stress-related apoptosis through an ROS-mediated pathway. This study provides new evidence to clarify the mechanism of OTA-induced nephrotoxicity.

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