Endoplasmic reticulum stress is accompanied by activation of NF-κB in amyotrophic lateral sclerosis

Endoplasmic reticulum stress and unfolded protein response: Roles in skeletal muscle atrophy

Skeletal muscle atrophy is commonly present in various pathological states, posing a huge burden on society and patients. Increased protein hydrolysis, decreased protein synthesis, inflammatory response, oxidative stress, mitochondrial dysfunction, endoplasmic reticulum stress (ERS) and unfolded protein response (UPR) are all important molecular mechanisms involved in the occurrence and development of skeletal muscle atrophy. The potential mechanisms of ERS and UPR in skeletal muscle atrophy are extremely complex and have not yet been fully elucidated. This article elucidates the molecular mechanisms of ERS and UPR, and discusses their effects on different types of muscle atrophy (muscle atrophy caused by disuse, cachexia, chronic kidney disease (CKD), diabetes mellitus (DM), amyotrophic lateral sclerosis (ALS), spinal muscular atrophy (SMA), spinal and bulbar muscular atrophy (SBMA), aging, sarcopenia, obesity, and starvation), and explores the preventive and therapeutic strategies targeting ERS and UPR in skeletal muscle atrophy, including inhibitor therapy and drug therapy. This review aims to emphasize the importance of endoplasmic reticulum (ER) in maintaining skeletal muscle homeostasis, which helps us further understand the molecular mechanisms of skeletal muscle atrophy and provides new ideas and insights for the development of effective therapeutic drugs and preventive measures for skeletal muscle atrophy.

Gibberellic acid targeting ZBTB16 reduces NF-κB dependent inflammatory stress in sepsis-induced neuroinflammation

OBJECTIVE

Sepsis is frequently complicated by neuroinflammation. Gibberellic acid (GA3) is recognized for its anti-inflammatory properties. In this study, our objective was to investigate whether GA3 could alleviate Nuclear factor-kappa B (NF-κB) -dependent inflammatory stress in sepsis-induced neuroinflammation.

METHODS

C57BL/6 J mice were administered 10 mg/kg lipopolysaccharide (LPS) to induce sepsis. BV2 cells were pre-incubated with GA3 and subjected lipopolysaccharide stimulation to replicate the inflammatory microglia during sepsis. Subsequently, we assessed the release of IL-6, TNF-α, and IL-1β, along with the expression of Zbtb16, NF-κB, and IκB. To investigate whether any observed anti-inflammatory effects of GA3 were mediated through a Zbtb16-dependent mechanism, Zbtb16 was silenced using siRNA.

RESULTS

GA3 improved the survival of sepsis mice and alleviated post-sepsis cognitive impairment. Additionally, GA3 attenuated microglial M1 activation (pro-inflammatory phenotype), inflammation, and neuronal damage in the brain. Moreover, GA3 inhibited the release of TNF-α, IL-6, and IL-1β in microglia stimulated with LPS. The NF-κB signaling pathway emerged as one of the key molecular pathways associated with the impact of GA3 on LPS-stimulated microglia. Lastly, GA3 upregulated Zbtb16 expression in microglia that had been downregulated by LPS. The inhibitory effects of GA3 on microglial M1 activation were partially reversed through siRNA knockdown of Zbtb16.

CONCLUSIONS

Pre-incubation of microglia with GA3 led to the upregulation of the NF-κB regulator, Zbtb16. This process counteracted LPS-induced microglial M1 activation, resulting in an anti-inflammatory effect upon subsequent LPS stimulation.

Involvement of IGF1 in endoplasmic reticulum stress contributes to cataract formation through regulating Nrf2/NF-κB signaling

Endoplasmic reticulum (ER) stress is reportedly involved in the development of ophthalmic diseases. This study aimed to investigate the role and potential mechanism of insulin-like growth factor 1 (IGF1) in ER stress. A mouse cataract model was constructed by subcutaneous injection of sodium selenite, and sh-IGF1 was used to evaluate the effect of silencing IGF1 on cataract progression. Slit-lamp and histological examination of the lens were performed to examine lens damage. The regulatory effects of IGF1 on inflammatory responses, oxidative stress, and ER stress were evaluated using ELISA, reverse transcription-quantitative PCR (RT-qPCR), and immunoblotting analysis. Tunicamycin was used to induce ER stress in the lens of epithelial cells. The NF-E2 related factor-2 (Nrf2) inhibitor ML385 and nuclear factor-κB (NF-κB) agonist diprovocim were used to confirm whether IGF1 regulates inflammation and ER stress through Nrf2/NF-κB signaling. Silencing IGF1 alleviated lens damage and reduced lens turbidity in the cataract mice. Silencing IGF1 inhibited inflammatory response, oxidative stress and ER stress response. Meanwhile, IGF1 was highly expressed in sodium selenite-treated lens epithelial cells. The ER stress agonist tunicamycin suppressed cell viability as well as induced ER stress, oxidative stress and inflammation. Silencing IGF1 increased cell viability, EdU-positive rate and migration. Also, silencing of IGF1 reduced inflammation and ER stress via regulating Nrf2/NF-κB pathway. This study reveals silencing IGF1 attenuated cataract through regulating Nrf2/NF-κB signaling, which shares novel insights into the underlying mechanism of cataract and provides potential therapeutic target for cataract.

M3 Receptor Pathway Stimulates Rapid Transcription of the CB1 Receptor Activation through Calcium Signalling and the CNR1 Gene Promoter

In this study, we have investigated a possible mechanism that enables CB₁/M₃ receptor cross-talk, using SH-SY5Y cells as a model system. Our results show that M₃ receptor activation initiates signaling that rapidly upregulates the CNR1 gene, resulting in a greatly potentiated CB₁ receptor response to agonists. Calcium homeostasis plays an essential intermediary role in this functional CB₁/M₃ receptor cross-talk. We show that M₃ receptor-triggered calcium release greatly increases CB₁ receptor expression via both transcriptional and translational activity, by enhancing CNR1 promoter activity. The co-expression of M₃ and CB₁ receptors in brain areas such as the nucleus accumbens and amygdala support the hypothesis that the altered synaptic plasticity observed after exposure to cannabinoids involves cross-talk with the M₃ receptor subtype. In this context, M₃ receptors and their interaction with the cannabinoid system at the transcriptional level represent a potential pharmacogenomic target not only for the develop of new drugs for addressing addiction and tolerance. but also to understand the mechanisms underpinning response stratification to cannabinoids.

Synergistic association of resveratrol and histone deacetylase inhibitors as treatment in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease associated with motor neuron degeneration, progressive paralysis and finally death. Despite the research efforts, currently there is no cure for ALS. In recent years, multiple epigenetic mechanisms have been associated with neurodegenerative diseases. A pathological role for histone hypoacetylation and the abnormal NF-κB/RelA activation involving deacetylation of lysines, with the exclusion of lysine 310, has been established in ALS. Recent findings indicate that the pathological acetylation state of NF-κB/RelA and histone 3 (H3) occurring in the SOD1(G93A) murine model of ALS can be corrected by the synergistic combination of low doses of the AMP-activated kinase (AMPK)-sirtuin 1 pathway activator resveratrol and the histone deacetylase (HDAC) inhibitors MS-275 (entinostat) or valproate. The combination of the epigenetic drugs, by rescuing RelA and the H3 acetylation state, promotes a beneficial and sexually dimorphic effect on disease onset, survival and motor neurons degeneration. In this mini review, we discuss the potential of the epigenetic combination of resveratrol with HDAC inhibitors in the ALS treatment.

Is Dutasteride a Therapeutic Alternative for Amyotrophic Lateral Sclerosis?

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that is characterized by the loss of upper and lower motor neurons (MNs) in the cerebral cortex, brainstem and spinal cord, with consequent weakness, atrophy and the progressive paralysis of all muscles. There is currently no medical cure, and riluzole and edaravone are the only two known approved drugs for treating this condition. However, they have limited efficacy, and hence there is a need to find new molecules. Dutasteride, a dual inhibitor of type 1 and type 2 5α-reductase (5AR) enzymes, the therapeutic purposes of which, to date, are the treatment of benign prostatic hyperplasia and androgenic alopecia, shows great anti-ALS properties by the molecular-topology methodology. Based on this evidence, this review aims to assess the effects of dutasteride on testosterone (T), progesterone (PROG) and 17β-estradiol (17BE) as a therapeutic alternative for the clinical improvement of ALS, based on the hormonal, metabolic and molecular pathways related to the pathogenesis of the disease. According to the evidence found, dutasteride shows great neuroprotective, antioxidant and anti-inflammatory effects. It also appears effective against glutamate toxicity, and it is capable of restoring altered dopamine activity (DA). These effects are achieved both directly and through steroid hormones. Therefore, dutasteride seems to be a promising molecule for the treatment of ALS, although clinical studies are required for confirmation.

The p97-Nploc4 ATPase complex plays a role in muscle atrophy during cancer and amyotrophic lateral sclerosis

BACKGROUND

The p97 complex participates in the degradation of muscle proteins during atrophy upon fasting or denervation interacting with different protein adaptors. We investigated whether and how it might also be involved in muscle wasting in cancer, where loss of appetite occurs, or amyotrophic lateral sclerosis (ALS), where motoneuron death causes muscle denervation and fatal paralysis.

METHODS

As cancer cachexia models, we used mice bearing colon adenocarcinoma C26, human renal carcinoma RXF393, or Lewis lung carcinoma, with breast cancer 4T1-injected mice as controls. As ALS models, we employed 129/SvHsd mice carrying the mutation G93A in human SOD1. The expression of p97 and its adaptors was analysed in their muscles by quantitative real-time polymerase chain reaction (qPCR) and western blot. We electroporated plasmids into muscles or treated mice with disulfiram (DSF) to test the effects of inhibiting p97 and nuclear protein localization protein 4 (Nploc4), one of its adaptors, on atrophy.

RESULTS

The mRNA levels of p97 were induced by 1.5-fold to 2-fold in tibialis anterior (TA) of all the cachectic models but not in the non-cachectic 4T1 tumour-bearing mice (P ≤ 0.05). Similarly, p97 was high both in mRNA and protein in TA from 17-week-old SOD1^G93A mice (P ≤ 0.01). Electroporation of a shRNA for murine p97 into mouse muscle reduced the fibre atrophy caused by C26 (P = 0.0003) or ALS (P ≤ 0.01). When we interrogated a microarray, we had previously generated for the expression of p97 adaptors, we found Derl1, Herpud1, Nploc4, Rnf31, and Hsp90ab1 induced in cachectic TA from C26-mice (Fold change > 1.2, adjusted P ≤ 0.05). By qPCR, we validated their inductions in TA of cachectic and ALS models and selected Nploc4 as the one also induced at the protein level by 1.5-fold (P ≤ 0.01). Electroporation of a CRISPR/Cas9 vector against Nploc4 into muscle reduced the fibre atrophy caused by C26 (P = 0.01) or ALS (P ≤ 0.0001). Because DSF uncouples p97 from Nploc4, we treated atrophying myotubes with DSF, and found accumulated mono and polyubiquitinated proteins and reduced degradation of long-lived proteins by 35% (P ≤ 0.0001), including actin (P ≤ 0.05). DSF halves Nploc4 in the soluble muscle fraction (P ≤ 0.001) and given to C26-bearing mice limited the body and muscle weight loss (P ≤ 0.05), with no effect on tumour growth.

CONCLUSIONS

Overall, cancer cachexia and ALS seem to display similar mechanisms of muscle wasting at least at the catabolic level. The p97-Nploc4 complex appears to have a crucial role in muscle atrophy during these disorders and disrupting this complex might serve as a novel drug strategy.

Beneficial and Dimorphic Response to Combined HDAC Inhibitor Valproate and AMPK/SIRT1 Pathway Activator Resveratrol in the Treatment of ALS Mice

Amyotrophic lateral sclerosis (ALS) is a fatal adult-onset neurodegenerative disorder. There is no cure and current treatments fail to slow the progression of the disease. Epigenetic modulation in the acetylation state of NF-kB RelA and the histone 3 (H3) protein, involved in the development of neurodegeneration, is a drugable target for the class-I histone deacetylases (HDAC) inhibitors, entinostat or valproate, and the AMP-activated kinase (AMPK)-sirtuin 1 pathway activator, resveratrol. In this study, we demonstrated that the combination of valproate and resveratrol can restore the normal acetylation state of RelA in the SOD1(G93A) murine model of ALS, in order to obtain the neuroprotective form of NF-kB. We also investigated the sexually dimorphic development of the disease, as well as the sex-sensibility to the treatment administered. We showed that the combined drugs, which rescued AMPK activation, RelA and the histone 3 acetylation state, reduced the motor deficit and the disease pathology associated with motor neuron loss and microglial reactivity, Brain-Derived Neurotrophic Factor (BDNF) and B-cell lymphoma-extra large (Bcl-xL) level decline. Specifically, vehicle-administered males showed earlier onset and slower progression of the disease when compared to females. The treatment, administered at 50 days of life, postponed the time of onset in the male by 22 days, but not in a significant way in females. Nevertheless, in females, the drugs significantly reduced symptom severity of the later phase of the disease and prolonged the mice’s survival. Only minor beneficial effects were produced in the latter stage in males. Overall, this study shows a beneficial and sexually dimorphic response to valproate and resveratrol treatment in ALS mice.

The Links between ALS and NF-κB

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease wherein motor neuron degeneration leads to muscle weakness, progressive paralysis, and death within 3-5 years of diagnosis. Currently, the cause of ALS is unknown but, as with several neurodegenerative diseases, the potential role of neuroinflammation has become an increasingly popular hypothesis in ALS research. Indeed, upregulation of neuroinflammatory factors have been observed in both ALS patients and animal models. One such factor is the inflammatory inducer NF-κB. Besides its connection to inflammation, NF-κB activity can be linked to several genes associated to familial forms of ALS, and many of the environmental risk factors of the disease stimulate NF-κB activation. Collectively, this has led many to hypothesize that NF-κB proteins may play a role in ALS pathogenesis. In this review, we discuss the genetic and environmental connections between NF-κB and ALS, as well as how this pathway may affect different CNS cell types, and finally how this may lead to motor neuron degeneration.

Nuclear factor-kappa B signaling in endometriotic stromal cells is not inhibited by progesterone owing to an aberrant endoplasmic reticulum stress response: a possible role for an altered inflammatory process in endometriosis

Endoplasmic reticulum (ER) stress serves as a key modulator of the inflammatory response by controlling nuclear factor-kappaB (NF-κB) signaling. Previous studies from our laboratory have reported an abnormal induction of ER stress linked to progesterone resistance in human endometriotic cells. Therefore, an aberrant ER stress response to progesterone might contribute to the altered inflammatory response observed in endometriotic tissues. To evaluate this hypothesis, we investigated whether ER stress is involved in regulation of NF-κB in endometrial stromal cells and whether induction of aberrant ER stress in endometriotic stromal cells affects pro-inflammatory cytokine production. We found that tunicamycin-induced ER stress inhibited NF-κB activation and pro-inflammatory cytokine (IL-6 and COX2) production in TNF-α- or IL-1β-treated normal endometrial stromal cells (NECSs). Tunicamycin increased the expression of A20 and C/EBPβ, which are negative regulators of NF-κB, and this increase inhibited NF-κB activity in NESCs incubated with TNF-α or IL-1β. Similarly, progesterone increased A20 and C/EBPβ expression through upregulation of ER stress in NESCs, resulting in inhibition of NF-κB activity and IL-6 and COX2 production. However, progesterone had no significant effects on induction of ER stress, A20 or C/EBPβ expression, NF-κB activity or IL-6 or COX2 production in ovarian endometriotic cyst stromal cells (ECSCs). In contrast, upregulation of ER stress by tunicamycin significantly reduced IL-6 and COX2 production by inhibiting NF-κB activity in ECSCs. In conclusion, our results suggest that NF-κB activity in endometriotic stromal cells was not inhibited because of an aberrant ER stress response to progesterone, resulting in an increase in pro-inflammatory cytokine production.

HuD regulates SOD1 expression during oxidative stress in differentiated neuroblastoma cells and sporadic ALS motor cortex

The neuronal RNA-binding protein (RBP) HuD plays an important role in brain development, synaptic plasticity and neurodegenerative diseases such as Parkinson's (PD) and Alzheimer's (AD). Bioinformatics analysis of the human SOD1 mRNA 3' untranslated region (3'UTR) demonstrated the presence of HuD binding adenine-uridine (AU)-rich instability-conferring elements (AREs). Using differentiated SH-SY5Y cells along with brain tissues from sporadic amyotrophic lateral sclerosis (sALS) patients, we assessed HuD-dependent regulation of SOD1 mRNA. In vitro binding and mRNA decay assays demonstrate that HuD specifically binds to SOD1 ARE motifs promoting mRNA stabilization. In SH-SY5Y cells, overexpression of full-length HuD increased SOD1 mRNA and protein levels while a dominant negative form of the RBP downregulated its expression. HuD regulation of SOD1 mRNA was also found to be oxidative stress (OS)-dependent, as shown by the increased HuD binding and upregulation of this mRNA after H₂O₂ exposure. This treatment also induced a shift in alternative polyadenylation (APA) site usage in SOD1 3'UTR, increasing the levels of a long variant bearing HuD binding sites. The requirement of HuD for SOD1 upregulation during oxidative damage was validated using a specific siRNA that downregulated HuD protein levels to 36% and prevented upregulation of SOD1 and 91 additional genes. In the motor cortex from sALS patients, we found increases in SOD1 and HuD mRNAs and proteins, accompanied by greater HuD binding to this mRNA as confirmed by RNA-immunoprecipitation (RIP) assays. Altogether, our results suggest a role of HuD in the post-transcriptional regulation of SOD1 expression during ALS pathogenesis.

Association of exosomal microRNAs in human ovarian follicular fluid with oocyte quality

The postponement of childbearing by women has led to an increase in infertility. The reproductive aging process leads to a decrease in both the quantity and quality of oocytes. The aim of this study was to investigate exosomal microRNAs in human ovarian follicular fluid and explore their potential association with oocyte quality. We collected ovarian follicle fluid from 68 patients and assigned the patients to A (superior oocyte quality) or B (poor oocyte quality) group according to their oocyte quality. Exosomal miRNAs were extracted, library constructed and sequenced using the Illumina HiSeq platform. Subsequently, we analyzed exosomal miRNA expression, predicted the miRNA target genes, and enriched Gene Ontology terms using GOSeq. Kyoto Encyclopedia of Genes and Genomes pathway analysis was performed using miRanda. A total of 47 miRNAs were found to be significantly differentially expressed between group A and group B (p < 0.05). Among nine differentially expressed miRNAs that were previously known, seven were upregulated in group B. In silico analysis indicated that several of these exosomal miRNAs were involved in pathways implicated in oocyte quality. Analysis of the expression of exosomal miRNAs in human ovarian follicular fluid showed that they were critical for maintaining oocyte quality. Our findings provide the basis for further investigations of the functions of exosomal miRNAs in the ovarian microenvironment and suggest that these exosomal miRNAs may be potential biomarkers for evaluating oocyte quality. The findings are potentially important to maintain oocyte quality in clinical settings.

Co-activation of Akt, Nrf2, and NF-κB signals under UPRER in torpid Myotis ricketti bats for survival

Bats hibernate to survive stressful conditions. Examination of whole cell and mitochondrial proteomes of the liver of Myotis ricketti revealed that torpid bats had endoplasmic reticulum unfolded protein response (UPRER), global reduction in glycolysis, enhancement of lipolysis, and selective amino acid metabolism. Compared to active bats, torpid bats had higher amounts of phosphorylated serine/threonine kinase (p-Akt) and UPRER markers such as PKR-like endoplasmic reticulum kinase (PERK) and activating transcription factor 4 (ATF4). Torpid bats also had lower amounts of the complex of Kelch-like ECH-associated protein 1 (Keap1), nuclear factor erythroid 2-related factor 2 (Nrf2), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) (p65)/I-κBα. Cellular redistribution of 78 kDa glucose-regulated protein (GRP78) and reduced binding between PERK and GRP78 were also seen in torpid bats. Evidence of such was not observed in fasted, cold-treated, or normal mice. These data indicated that bats activate Akt, Nrf2, and NF-κB via the PERK-ATF4 regulatory axis against endoplasmic reticulum stresses during hibernation.

Copper-ATSM as a Treatment for ALS: Support from Mutant SOD1 Models and Beyond

The blood-brain barrier permeant, copper-containing compound, CuII(atsm), has successfully progressed from fundamental research outcomes in the laboratory through to phase 2/3 clinical assessment in patients with the highly aggressive and fatal neurodegenerative condition of amyotrophic lateral sclerosis (ALS). The most compelling outcomes to date to indicate potential for disease-modification have come from pre-clinical studies utilising mouse models that involve transgenic expression of mutated superoxide dismutase 1 (SOD1). Mutant SOD1 mice provide a very robust mammalian model of ALS with high validity, but mutations in SOD1 account for only a small percentage of ALS cases in the clinic, with the preponderant amount of cases being sporadic and of unknown aetiology. As per other putative drugs for ALS developed and tested primarily in mutant SOD1 mice, this raises important questions about the pertinence of CuII(atsm) to broader clinical translation. This review highlights some of the challenges associated with the clinical translation of new treatment options for ALS. It then provides a brief account of pre-clinical outcomes for CuII(atsm) in SOD1 mouse models of ALS, followed by an outline of additional studies which report positive outcomes for CuII(atsm) when assessed in cell and mouse models of neurodegeneration which do not involve mutant SOD1. Clinical evidence for CuII(atsm) selectively targeting affected regions of the CNS in patients is also presented. Overall, this review summarises the existing evidence which indicates why clinical relevance of CuII(atsm) likely extends beyond the context of cases of ALS caused by mutant SOD1.

Role of Nuclear Factor Kappa B (NF-κB) Signalling in Neurodegenerative Diseases: An Mechanistic Approach

A transcriptional regulatory nuclear factor kappa B (NF-κB) protein is a modulator of cellular biological activity via binding to a promoter region in the nucleus and transcribing various protein genes. The recent research implicated the intensive role of nuclear factor kappa B (NF-κB) in diseases like autoimmune disorder, inflammatory, cardiovascular and neurodegenerative diseases. Therefore, targeting the nuclear factor kappa B (NF-κB) protein offers a new opportunity as a therapeutic approach. Activation of IκB kinase/NF-κB signaling pathway leads to the development of various pathological conditions in human beings, such as neurodegenerative, inflammatory disorders, autoimmune diseases, and cancer. Therefore, the transcriptional activity of IκB kinase/NF- κB is strongly regulated at various cascade pathways. The nuclear factor NF-kB pathway plays a major role in the expression of pro-inflammatory genes, including cytokines, chemokines, and adhesion molecules. In response to the diverse stimuli, the cytosolic sequestered NF-κB in an inactivated form by binding with an inhibitor molecule protein (IkB) gets phosphorylated and translocated into the nucleus further transcribing various genes necessary for modifying various cellular functions. The various researches confirmed the role of different family member proteins of NF-κB implicated in expressing various genes products and mediating various cellular cascades. MicroRNAs, as regulators of NF- κB microRNAs play important roles in the regulation of the inflammatory process. Therefore, the inhibitor of NF-κB and its family members plays a novel therapeutic target in preventing various diseases. Regulation of NF- κB signaling pathway may be a safe and effective treatment strategy for various disorders.

Calcium signalling in mammalian cell lines expressing wild type and mutant human α1-Antitrypsin

A possible role for calcium signalling in the autosomal dominant form of dementia, familial encephalopathy with neuroserpin inclusion bodies (FENIB), has been proposed, which may point towards a mechanism by which cells could sense and respond to the accumulation of mutant serpin polymers in the endoplasmic reticulum (ER). We therefore explored possible defects in Ca²⁺-signalling, which may contribute to the pathology associated with another serpinopathy, α₁-antitrypsin (AAT) deficiency. Using CHO K1 cell lines stably expressing a wild type human AAT (MAAT) and a disease-causing polymer-forming variant (ZAAT) and the truncated variant (NHK AAT), we measured basal intracellular free Ca²⁺, its responses to thapsigargin (TG), an ER Ca²⁺-ATPase blocker, and store-operated Ca²⁺-entry (SOCE). Our fura2 based Ca²⁺ measurements detected no differences between these 3 parameters in cell lines expressing MAAT and cell lines expressing ZAAT and NHK AAT mutants. Thus, in our cell-based models of α1-antitrypsin (AAT) deficiency, unlike the case for FENIB, we were unable to detect defects in calcium signalling.

Anti-Neuroinflammatory Effect of Jaeumganghwa-Tang in an Animal Model of Amyotrophic Lateral Sclerosis

Neuroinflammation is considered a critical factor in the pathologic mechanisms of amyotrophic lateral sclerosis (ALS). This study examined the levels of neuroinflammatory proteins in the spinal cord of JGT-treated hSOD1^G93A transgenic mice to determine the effect of Jaeumganghwa-Tang (JGT) on neuroinflammation. Twelve 8-week-old male experimental mice were randomly allocated to three groups: a non-transgenic group, a hSOD1^G93A transgenic group, and a hSOD1^G93A transgenic group that received JGT 1 mg/g orally once daily for 6 weeks. After 6 weeks, the spinal cord tissues were analyzed for inflammatory proteins (Iba-1, toll-like receptor 4, and tumor necrosis factor-α) and oxidative stress-related proteins (transferrin, ferritin, HO1, and NQO1) by Western blot analysis. Administration of JGT significantly delayed motor function impairment and reduced oxidative stress in hSOD1^G93A transgenic mice. JGT effectively ameliorated neuroinflammation mechanisms by downregulating TLR4-related signaling proteins and improving iron homeostasis in the spinal cord of hSOD1^G93A mice. JGT could help to decrease neuroinflammation and protect neuronal cells by strengthening the immune response in the central nervous system. This is the first study to demonstrate the role of JGT in neuroinflammation in an animal model of ALS.

Sigma-1 receptor protects against endoplasmic reticulum stress-mediated apoptosis in mice with cerebral ischemia/reperfusion injury

Reports have showed that Sigma-1 receptor (Sig-1R) activation can protect neurons against cerebral ischemia/reperfusion (I/R) injury in mice and alleviate endoplasmic reticulum (ER) stress in cultured cells, but little known is about the protective role of Sig-1R on ER stress induced by cerebral I/R. The purpose of this study was to determine whether Sig-1R exerts a protective effect against ER stress-mediated apoptosis in cerebral I/R using a 15-min bilateral common carotid artery occlusion (BCCAO) mouse model. At 72 h after reperfusion in BCCAO mice, we found that Sig-1R knockout (Sig-1R KO) significantly increased terminal dUTP nick-end labeling (TUNEL)-positive cells and nuclear structural damage in cortical neurons. Treatment with the Sig-1R agonist PRE084 once daily for three consecutive days reduced the number of TUNEL-positive cells and improved the ultrastructural damage of neurons in the cerebral cortex. These protective effects could be blocked by the Sig-1R antagonist BD1047. Then, we used BCCAO mice at 24 h after reperfusion to detect the expression of ER stress-mediated apoptotic pathway proteins. We found that expression of the pro-apoptotic proteins p-PERK, p-eIF2α, ATF, CHOP, p-IRE, p-JNK, Bim, PUMA, cleaved-caspase-12 and cleaved-caspase-3 was significantly increased and that expression of the anti-apoptotic protein Bcl-2 was significantly decreased in Sig-1R KO-BCCAO mice compared with BCCAO mice. Meanwhile, we found that treatment with PRE084 twice a day decreased pro-apoptotic protein expression and increased anti-apoptotic protein expression. The effects of PRE084 were blocked by the Sig-1R antagonist BD1047. These results suggest that Sig-1R activation inhibits ER stress-mediated apoptosis in BCCAO mice, indicating that Sig-1R may be a therapeutic target for neuroprotection particularly relevant to ER stress-induced apoptosis after cerebral I/R injury.

Nuclear factor-kappa B-dependent X-box binding protein 1 signalling promotes the proliferation of nucleus pulposus cells under tumour necrosis factor alpha stimulation

OBJECTIVES

Tumour necrosis factor alpha (TNF-α) expressed by nucleus pulposus cells (NPCs) plays a critical role in intervertebral disc (IVD) degeneration. A key unfolded protein response (UPR) component, X-box binding protein 1 (XBP1) and nuclear factor-kappa B (NF-κB) are essential for cell survival and proliferation. The aim of our study was to elucidate the roles of XBP1 and NF-κB in IVD degeneration (IDD).

MATERIALS AND METHODS

Rat NPCs were cultured with TNF-α in the presence or absence of XBP1 and NF-κB-p65 small interfering RNA. The associated genes and proteins were evaluated through quantitative real-time PCR, Western blot analyses and immunofluorescence staining to monitor UPR and NF-κB signalling and identify the regulatory mechanism of p65 by XBP1. Cell counting kit-8 assay, cell cycle analysis and related gene and protein expression were performed to examine the proliferation of NPCs.

RESULTS

The acute exposure of TNF-α accelerated the proliferation of rat NPCs by activating the UPR/XBP1 pathway. XBP1 signalling favoured the phosphorylation and nuclear translocation of p65 subunit of NF-κB. The activation of NF-κB in the later phase also enhanced NPC proliferation.

CONCLUSIONS

Unfolded protein response reinforces the survival and proliferation of NPCs under TNF-α stimulation by activating the XBP1 pathway, and NF-κB serves as a vital mediator in these events. The XBP1 signalling of UPR can be a novel therapeutic target in IDD.

In vitro protein expression changes in RAW 264.7 cells and HUVECs treated with dialyzed coffee extract by immunoprecipitation high performance liquid chromatography

RAW 264.7 cells and HUVECs were compared to evaluate the effects of dialyzed coffee extract (DCE) and artificial coffee (AC). Immunoprecipitation high performance liquid chromatography (IP-HPLC) showed DCE-2.5- (equivalent to 2.5 cups of coffee a day) and DCE-5-induced protein expression that was beneficial to human health, i.e., they led to significant increases in proliferation-, immunity-, cellular protection-, antioxidant signaling-, and osteogenesis-related proteins but decreases in inflammation-, NFkB signaling-, cellular apoptosis-, and oncogenic signaling-related proteins in RAW 264.7 cells, and slight decreases in angiogenesis-related proteins in HUVECs. These protein expression changes were less frequently observed for DCE-10 treatment, while AC treatment induced very different changes in protein expression. We suggest that the favorable cellular effects of DCE were derived from minor coffee elements that were absent in AC, and that the reduced effects of DCE-10 compared with those of DCE-2.5 or DCE-5 might have been caused by greater adverse reactions to caffeine and chlorogenic acid in DCE-10 than DCE-2.5 or DCE-5. IP-HPLC results suggested that minor coffee elements in DCE might play beneficial roles in the global protein expression of proliferation-, immunity-, anti-inflammation-, cell protection-, antioxidant-, anti-apoptosis-, anti-oncogenesis-, and osteogenesis-related proteins in RAW 264.7 cells and enhance anti-angiogenic signaling in HUVECs.

Inhibition of granzyme B activity blocks inflammation induced by lipopolysaccharide through regulation of endoplasmic reticulum stress signaling in NK92 cells

Granzyme B (GrB) is a serine protease that is expressed in the lytic granules of natural killer (NK) cells and cytotoxic T lymphocytes (CTL), and which has been widely reported to serve a crucial role for target cell apoptosis. GrB may serve a non‑cytotoxic role in inflammation, but the evidence remains unclear. The present study aimed to establish an inflammatory cell model by using NK92 cells stimulated with lipopolysaccharide (LPS) to investigate whether GrB was involved in the development of inflammation. The extracellular levels of tumor necrosis factor‑α (TNF‑α), interleukin‑1β (IL‑1β) and GrB were examined by ELISA, and it was demonstrated that LPS treatment increased the extracellular levels of TNF‑α, IL‑1β and GrB, and these increased expression levels were inhibited by pretreatment with the GrB inhibitor serpin A3N (SA3N). The protein expression levels of glucose‑regulated protein 78 (GRP78), C/EBP homologous protein (CHOP), nuclear factor‑κB (NF‑κB), inhibitor of NF‑κB (IκBα) and GrB were examined by western blot analysis. The results demonstrated that LPS stimulation increased the expression levels of GRP78, CHOP, NF‑κB and GrB, and decreased the expression of IκBα, and these changes were inhibited by SA3N, which indicated that inhibition of GrB activity may suppress endoplasmic reticulum (ER) stress signaling. Therefore, it was suggested that GrB may be a potential pro‑inflammatory factor, and inhibition of GrB activity may aid the prevention of the development of inflammation by suppressing ER stress signaling.

Circadian Rhythm Dysfunction Accelerates Disease Progression in a Mouse Model With Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease caused by interactions between environmental factors and genetic susceptibility. Circadian rhythm dysfunction (CRD) is a significant contributor to neurodegenerative conditions such as Alzheimer’s disease and Parkinson’s disease. However, whether CRD contributes to the progression of ALS remains little known. We performed behavioral and physiological tests on SOD1G93A ALS model mice with and without artificially induced CRD, and on wild-type controls; we also analyzed spinal cord samples histologically for differences between groups. We found that CRD accelerated the disease onset and progression of ALS in model mice, as demonstrated by aggravated functional deficits and weight loss, as well as increased motor neuron loss, activated gliosis, and nuclear factor κB-mediated inflammation in the spinal cord. We also found an increasing abundance of enteric cyanobacteria in the ALS model mice shortly after disease onset that was further enhanced by CRD. Our study provides initial evidence on the CRD as a risk factor for ALS, and intestinal cyanobacteria may be involved.

Astrocytes expressing ALS-linked mutant FUS induce motor neuron death through release of tumor necrosis factor-alpha

Mutations in fused in sarcoma (FUS) are linked to amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disease affecting both upper and lower motor neurons. While it is established that astrocytes contribute to the death of motor neurons in ALS, the specific contribution of mutant FUS (mutFUS) through astrocytes has not yet been studied. Here, we used primary astrocytes expressing a N‐terminally GFP tagged R521G mutant or wild‐type FUS (WTFUS) and show that mutFUS‐expressing astrocytes undergo astrogliosis, damage co‐cultured motor neurons via activation of an inflammatory response and produce conditioned medium (ACM) that is toxic to motor neurons in isolation. Time lapse imaging shows that motor neuron cultures exposed to mutFUS ACM, but not WTFUS ACM, undergo significant cell loss, which is preceded by progressive degeneration of neurites. We found that Tumor Necrosis Factor‐Alpha (TNFα) is secreted into ACM of mutFUS‐expressing astrocytes. Accordingly, mutFUS astrocyte‐mediated motor neuron toxicity is blocked by targeting soluble TNFα with neutralizing antibodies. We also found that mutant astrocytes trigger changes to motor neuron AMPA receptors (AMPAR) that render them susceptible to excitotoxicity and AMPAR‐mediated cell death. Our data provide the first evidence of astrocytic involvement in FUS‐ALS, identify TNFα as a mediator of this toxicity, and provide several potential therapeutic targets to protect motor neurons in FUS‐linked ALS.

Cannabinoid Receptor Type 1 Agonist ACEA Protects Neurons from Death and Attenuates Endoplasmic Reticulum Stress-Related Apoptotic Pathway Signaling

Neurodegeneration is the result of progressive destruction of neurons in the central nervous system, with unknown causes and pathological mechanisms not yet fully elucidated. Several factors contribute to neurodegenerative processes, including neuroinflammation, accumulation of neurotoxic factors, and misfolded proteins in the lumen of the endoplasmic reticulum (ER). Endocannabinoid signaling has been pointed out as an important modulatory system in several neurodegeneration-related processes, inhibiting the inflammatory response and increasing neuronal survival. Thus, we investigated the presumptive protective effect of the selective cannabinoid type 1 (CB1) receptor agonist arachidonyl-2'-chloroethylamide (ACEA) against inflammatory (lipopolysaccharide, LPS) and ER stress (tunicamycin) stimuli in an in vitro neuronal model (Neuro-2a neuroblastoma cells). Cell viability analysis revealed that ACEA was able to protect against cell death induced by LPS and tunicamycin. This neuroprotective effect occurs via the CB1 receptor in the inflammation process and via the transient receptor potential of vanilloid type-1 (TRPV1) channel in ER stress. Furthermore, the immunoblotting analyses indicated that the neuroprotective effect of ACEA seems to involve the modulation of eukaryotic initiation factor 2 (eIF2α), transcription factor C/EBP homologous protein (CHOP), and caspase 12, as well as the survival/death p44/42 MAPK, ERK1/2-related signaling pathways. Together, these data suggest that the endocannabinoid system is a potential therapeutic target in neurodegenerative processes, especially in ER-related neurodegenerative diseases.

Calcium homeostasis and endoplasmic reticulum stress are involved in Salvianolic acid B-offered protection against cardiac toxicity of arsenic trioxide

Arsenic trioxide (ATO) is a potent anticancer agent used to treat acute promyelocytic leukemia. However, its cardiotoxicity limits ATO’s widespread clinical use. Previous studies demonstrated that ATO may aggravate Ca²⁺ overload and promote endoplasmic reticulum stress (ERS). Salvianolic acid B (Sal B) is cardioprotective against ATO and enhances ATO’s anticancer activities. The present study assessed whether the Sal B protective effect was related to maintenance of Ca²⁺ homeostasis and inhibition of ER stress. Male BALB/c mice were injected with ATO or ATO+Sal B once a day via the tail vein for 2 weeks. We then detected the effects of Sal B in real time using adult rat ventricular cardiomyocytes in vitro using an IonOptix MyoCam system. Sal B treatment alleviated ATO-induced abnormal cardiac contractions and Ca²⁺ homeostasis imbalance. Sal B increased sarcoplasmic reticulum Ca²⁺-ATPase (SERCA) activity, regulated Ca²⁺ handling protein expression, and decreased expression of ERS proteins. Our results demonstrate that the cardioprotective effect of Sal B correlates with SERCA modulation, maintenance of Ca²⁺ homeostasis, and inhibition of ER stress. These findings suggest Sal B may ameliorate ATO cardiotoxicity during clinical application.

Sustained HSP25 Expression Induces Clasmatodendrosis via ER Stress in the Rat Hippocampus

Heat shock protein (HSP) 25 (murine/rodent 25 kDa, human 27 kDa) is one of the major astroglial HSP families, which has a potent anti-apoptotic factor contributing to a higher resistance of astrocytes to the stressful condition. However, impaired removals of HSP25 decrease astroglial viability. In the present study, we investigated whether HSP25 is involved in astroglial apoptosis or clasmatodendrosis (autophagic astroglial death) in the rat hippocampus induced by status epilepticus (SE). Following SE, HSP25 expression was transiently increased in astrocytes within the dentate gyrus (DG), while it was sustained in CA1 astrocytes until 4 weeks after SE. HSP25 knockdown exacerbated SE-induced apoptotic astroglial degeneration, but mitigated clasmatodendrosis accompanied by abrogation of endoplasmic reticulum (ER) stress without changed seizure susceptibility or severity. These findings suggest that sustained HSP25 induction itself may result in clasmatodendrosis via prolonged ER stress. To the best of our knowledge, the present study demonstrates for the first time the double-edge properties of HSP25 in astroglial death induced by SE.

Panel of Oxidative Stress and Inflammatory Biomarkers in ALS: A Pilot Study

Background: Pathophysiological mechanisms that contribute to neurodegeneration in Amyotrophic Lateral Sclerosis (ALS) include oxidative stress and inflammation. We conducted a preliminary study to explore these mechanisms, to discuss their link in ALS, and to determine the feasibility of incorporating this combined analysis into current biomarkers research. Methods: We enrolled 10 ALS patients and 10 controls. We measured the activities of glutathione peroxidase, glutathione reductase, superoxyde dismutase (SOD), and the levels of serum total antioxidant status (TAS), malondialdehyde (MDA), 8-hydroxy-2’-deoxyguanosine (8-OHdG), and glutathione status (e.g. glutathione disulfide, GSSG/reduced glutathione, GSH). We analysed the concentrations of homocysteine, several cytokines, vitamins and metals by standard methods used in routine practice. Results: There was a significant decrease in TAS levels (p=0.027) and increase in 8-OHdG (p=0.014) and MDA (p=0.011) levels in ALS patients. We also observed a significantly higher GSSG/GSH ratio (p=0.022), and IL-6 (p=0.0079) and IL-8 (p=0.009) concentrations in ALS patients. Correlations were found between biological and clinical markers (homosysteine vs. clinical status at diagnosis, p=0.02) and between some biological markers such as IL-6 vs. GSSG/GSH (p=0.045) or SOD activity (p=0.017). Conclusion: We confirmed the systemic alteration of both the redox and the inflammation status in ALS patients, and we observed a link with some clinical parameters. These promising results encourage us to pursue this study with collection of combined oxidative stress and inflammatory markers.

Key contribution of eIF4H-mediated translational control in tumor promotion

Dysregulated expression of translation initiation factors has been associated with carcinogenesis, but underlying mechanisms remains to be fully understood. Here we show that eIF4H (eukaryotic translation initiation factor 4H), an activator of the RNA helicase eIF4A, is overexpressed in lung carcinomas and predictive of response to chemotherapy. In lung cancer cells, depletion of eIF4H enhances sensitization to chemotherapy, decreases cell migration and inhibits tumor growth in vivo, in association with reduced translation of mRNA encoding cell-proliferation (c-Myc, cyclin D1) angiogenic (FGF-2) and anti-apoptotic factors (CIAP-1, BCL-xL). Conversely, each isoform of eIF4H acts as an oncogene in NIH3T3 cells by stimulating transformation, invasion, tumor growth and resistance to drug-induced apoptosis together with increased translation of IRES-containing or structured 5′UTR mRNAs. These results demonstrate that eIF4H plays a crucial role in translational control and can promote cellular transformation by preferentially regulating the translation of potent growth and survival factor mRNAs, indicating that eIF4H is a promising new molecular target for cancer therapy.

Salubrinal reduces oxidative stress, neuroinflammation and impulsive-like behavior in a rodent model of traumatic brain injury

Traumatic brain injury (TBI) is the leading cause of trauma related morbidity in the developed world. TBI has been shown to trigger secondary injury cascades including endoplasmic reticulum (ER) stress, oxidative stress, and neuroinflammation. The link between secondary injury cascades and behavioral outcome following TBI is poorly understood warranting further investigation. Using our validated rodent blast TBI model, we examined the interaction of secondary injury cascades following single injury and how these interactions may contribute to impulsive-like behavior after a clinically relevant repetitive TBI paradigm. We targeted these secondary pathways acutely following single injury with the cellular stress modulator, salubrinal (SAL). We examined the neuroprotective effects of SAL administration on significantly reducing ER stress: janus-N-terminal kinase (JNK) phosphorylation and C/EBP homology protein (CHOP), oxidative stress: superoxide and carbonyls, and neuroinflammation: nuclear factor kappa beta (NFκB) activity, inducible nitric oxide synthase (iNOS) protein expression, and pro-inflammatory cytokines at 24h post-TBI. We then used the more clinically relevant repeat injury paradigm and observed elevated NFκB and iNOS activity. These injury cascades were associated with impulsive-like behavior measured on the elevated plus maze. SAL administration attenuated secondary iNOS activity at 72h following repetitive TBI, and most importantly prevented impulsive-like behavior. Overall, these results suggest a link between secondary injury cascades and impulsive-like behavior that can be modulated by SAL administration.

Selected gene profiles of stressed NSC-34 cells and rat spinal cord following peripheral nerve reconstruction and minocycline treatment

The present study was conducted to investigate the effects of minocycline on the expression of selected transcriptional and translational profiles in the rat spinal cord following sciatic nerve (SNR) transection and microsurgical coaptation. The mRNA and protein expression levels of B cell lymphoma-2 (Bcl-2), Bcl-2-associated X protein (Bax), caspase-3, major histocompatibility complex I (MHC I), tumor necrosis factor-α (TNF-α), activating transcription factor 3 (ATF3), vascular endothelial growth factor (VEGF), matrix metalloproteinase 9 (MMP9), and growth associated protein-43 (GAP-43) were monitored in the rat lumbar spinal cord following microsurgical reconstruction of the sciatic nerves and minocycline treatment. The present study used semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry. As a PCR analysis of spinal cord tissue enabled the examination of the expression patterns of all cell types including glia, the motorneuron-like NSC-34 cell line was used to investigate expression level changes in motorneurons. As stressors, oxygen glucose deprivation (OGD) and lipopolysaccharide (LPS) treatment were performed. SNR did not induce significant degeneration of ventral horn motorneurons, whereas microglia activation and synaptic terminal retraction were detectable. All genes were constitutively expressed at the mRNA and protein levels in untreated spinal cord and control cells. SNR significantly increased the mRNA expression levels of all genes, albeit only temporarily. In all genes except MMP9 and GAP-43, the induction was seen ipsilaterally and contralaterally. The effects of minocycline were moderate. The expression levels of MMP9, TNF-α, MHC I, VEGF, and GAP-43 were reduced, whereas those of Bax and Bcl-2 were unaffected. OGD, but not LPS, was toxic for NSC-34 cells. No changes in the expression levels of Bax, caspase-3, MHC I or ATF3 were observed. These results indicated that motorneurons were not preferentially or solely responsible for SNR-mediated upregulation of these genes. MMP9, TNF-α, VEGF and Bcl-2 were stress-activated. These results suggest that a substantial participation of motorneurons in gene expression levels in vivo. Minocycline was also shown to have inhibitory effects. The nuclear factor-κB signalling pathway may be a possible target of minocycline.

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

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

On the Roles of the Transient Receptor Potential Canonical 3 (TRPC3) Channel in Endothelium and Macrophages: Implications in Atherosclerosis

In the cardiovascular and hematopoietic systems the Transient Receptor Potential Canonical 3 (TRPC3) channel has a well-recognized role in a number of signaling mechanisms that impact the function of diverse cells and tissues in physiology and disease. The latter includes, but is not limited to, molecular and cellular mechanisms associated to the pathogenesis of cardiac hypertrophy, hypertension and endothelial dysfunction. Despite several of these functions being closely related to atherorelevant mechanisms, the potential roles of TRPC3 in atherosclerosis, the major cause of coronary artery disease, have remained largely unexplored. Over recent years, a series of studies from the authors' laboratory revealed novel functions of TRPC3 in mechanisms related to endothelial inflammation, monocyte adhesion to endothelium and survival and apoptosis of macrophages. The relevance of these new TRPC3 functions to atherogenesis has recently began to receive validation through studies in mouse models of atherosclerosis with conditional gain or loss of TRPC3 function. This chapter summarizes these novel findings and provides a discussion of their impact in the context of atherosclerosis, in an attempt to delineate a framework for further exploration of this terra incognita in the TRPC field.

Inflammation and neuronal death in the motor cortex of the wobbler mouse, an ALS animal model

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder of the upper and lower motor neurons, characterized by rapid progressive weakness, muscle atrophy, dysarthria, dysphagia, and dyspnea. Whereas the exact cause of ALS remains uncertain, the wobbler mouse (phenotype WR; genotype wr/wr) equally develops a progressive degeneration of motor neurons in the spinal cord and motor cortex with striking similarities to sporadic human ALS, suggesting the possibility of a common pathway to cell death.

METHODS

With the aid of immunohistochemistry, confocal laser scanning microscopy, and transmission electron microscopy techniques, we analyze the proliferation behavior of microglial cells and astrocytes. We also investigate possible motor neuron death in the mouse motor cortex at different stages of the wobbler disease, which so far has not received much attention.

RESULTS

An abnormal density of Iba-1-positive microglial cells expressing pro-inflammatory tumor necrosis factor (TNF) alpha- and glial fibrillary acidic protein (GFAP)-positive activated astroglial cells was detected in the motor cortex region of the WR mouse 40 days postnatal (d.p.n.). Motor neurons in the same area show caspase 3 activation indicating neurodegenerative processes, which may cause progressive paralysis of the WR mice. It could also cause cell degeneration, such as vacuolization, dilation of the ER, and swollen mitochondria at the same time, and support the assumption that inflammation might be an important contributing factor of motor neuron degeneration. This would appear to be confirmed by the fact that there was no conspicuous increase of microglial cells and astrocytes in the motor cortex of control mice at any time.

CONCLUSIONS

Activated microglial cells secrete a variety of pro-inflammatory and neurotoxic factors, such as TNF alpha, which could initiate apoptotic processes in the affected wobbler motor neurons, as reflected by caspase 3 activation, and thus, the neuroinflammatory processes might influence or exacerbate the neurodegeneration. Although it remains to be clarified whether the immune response is primary or secondary and how harmful or beneficial it is in the WR motor neuron disease, anti-inflammatory treatment might be considered.

Intravenous injection of l-BMAA induces a rat model with comprehensive characteristics of amyotrophic lateral sclerosis/Parkinson-dementia complex

Non-protein amino acid beta-N-methylamino-l-alanine (l-BMAA) is a neurotoxin that was associated with the high incidence of Amyotrophic Lateral Sclerosis/Parkinson-Dementia Complex (ALS/PDC) in Guam. This neurotoxin has been implicated as a potential environmental factor in amyotrophic lateral sclerosis, Alzheimer's disease and other neurodegenerative diseases, and was found to accumulate in brain tissues of ALS/PDC patients. It is extremely important to establish a reliable animal model that has the comprehensive characteristics of ALS/PDC for studying mechanisms underlying neurodegeneration, and exploring effective therapies. However, very few good animal models that mimic ALS/PDC have been established. In this study, an ideal rat model that mimicked most characteristics of ALS/PDC was established by administering continuous intravenous (i.v.) injections of neurotoxic l-BMAA. Based on the data obtained, it was demonstrated that continuous i.v. injections of l-BMAA induced mitochondrial morphology and structural changes, astrogliosis, motor neuronal death, and other relative functional changes, which led to the overexpression of pro-inflammatory cytokines cyclooxygenase-2 (COX-2), nuclear factor kappa B (NF-κB) and tumor necrosis factor-alpha (TNF-α), and resulted in the upregulation of glycogen synthase kinase-3 (GSK3), downregulation of astrocytic glutamate transporter-1 (GLT-1), accumulation of microtubule-associated protein tau and cytosolic aggregates of TAR DNA-binding protein-43 (TDP-43) in degenerating motor neurons. These results suggest that this model could be used as a useful tool for the mechanistic and therapeutic study of ALS/PDC.

Ubiquilin-2 drives NF-κB activity and cytosolic TDP-43 aggregation in neuronal cells

Background

Mutations in the gene encoding Ubiquilin-2 (UBQLN2) are linked to amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). UBQLN2 plays a central role in ubiquitin proteasome system (UPS) and UBQLN2 mutants can form cytoplasmic aggregates in vitro and in vivo.

Results

Here, we report that overexpression of WT or mutant UBQLN2 species enhanced nuclear factor κB (NF-κB) activation in Neuro2A cells. The inhibition of NF-κB stress-mediated activation with SB203580, a p38 MAPK inhibitor, demonstrated a role for MAPK in NF-κB activation by UBQLN2 species. Live cell imaging and microscopy showed that UBQLN2 aggregates are dynamic structures that promote cytoplasmic accumulation of TAR DNA-binding protein (TDP-43), a major component of ALS inclusion bodies. Furthermore, up-regulation of UBQLN2 species in neurons caused an ER-stress response and increased their vulnerability to death by toxic mediator TNF-α. Withaferin A, a known NF-κB inhibitor, reduced mortality of Neuro2A cells overexpressing UBQLN2 species.

Conclusions

These results suggest that UBQLN2 dysregulation in neurons can drive NF-κB activation and cytosolic TDP-43 aggregation, supporting the concept of pathway convergence in ALS pathogenesis. These Ubiquilin-2 pathogenic pathways might represent suitable therapeutic targets for future ALS treatment.

Electronic supplementary material

The online version of this article (doi:10.1186/s13041-015-0162-6) contains supplementary material, which is available to authorized users.

Molecular Consequences of Proprotein Convertase 1/3 (PC1/3) Inhibition in Macrophages for Application to Cancer Immunotherapy: A Proteomic Study

Macrophages provide the first line of host immune defense. Their activation triggers the secretion of pro-inflammatory cytokines and chemokines recruiting other immune cells. In cancer, macrophages present an M2 anti-inflammatory phenotype promoting tumor growth. In this way, strategies need to be develop to reactivate macrophages. Previously thought to be expressed only in cells with a neural/neuroendocrine phenotype, the proprotein convertase 1/3 has been shown to also be expressed in macrophages and regulated as a function of the Toll-like receptor immune response. Here, we investigated the intracellular impact of the down-regulation of the proprotein convertase 1/3 in NR8383 macrophages and confirmed the results on macrophages from PC1/3 deficient mice. A complete proteomic study of secretomes and intracellular proteins was undertaken and revealed that inhibition of proprotein convertase 1/3 orient macrophages toward an M1 activated phenotype. This phenotype is characterized by filopodial extensions, Toll-like receptor 4 MyD88-dependent signaling, calcium entry augmentation and the secretion of pro-inflammatory factors. In response to endotoxin/lipopolysaccharide, these intracellular modifications increased, and the secreted factors attracted naïve T helper lymphocytes to promote the cytotoxic response. Importantly, the application of these factors onto breast and ovarian cancer cells resulted in a decrease viability or resistance. Under inhibitory conditions using interleukin 10, PC1/3-knockdown macrophages continued to secrete inflammatory factors. These data indicate that targeted inhibition of proprotein convertase 1/3 could represent a novel type of immune therapy to reactivate intra-tumoral macrophages.

Notch pathway is activated in cell culture and mouse models of mutant SOD1-related familial amyotrophic lateral sclerosis, with suppression of its activation as an additional mechanism of neuroprotection for lithium and valproate

Amyotrophic lateral sclerosis (ALS) is an idiopathic and lethal neurodegenerative disease that currently has no effective treatment. A recent study found that the Notch signaling pathway was up-regulated in a TAR DNA-binding protein-43 (TDP-43) Drosophila model of ALS. Notch signaling acts as a master regulator in the central nervous system. However, the mechanisms by which Notch participates in the pathogenesis of ALS have not been completely elucidated. Recent studies have shown that the mood stabilizers lithium and valproic acid (VPA) are able to regulate Notch signaling. Our study sought to confirm the relationship between the Notch pathway and ALS and whether the Notch pathway contributes to the neuroprotective effects of lithium and VPA in ALS. We found that the Notch pathway was activated in in vitro and in vivo models of ALS, and suppression of Notch activation with a Notch signaling inhibitor, N-[N-(3,5-difluorophenacetyl-L-alanyl)]-S-phenylglycine t-butyl ester (DAPT) and Notch1 siRNA significantly reduced neuronal apoptotic signaling, as evidenced by the up-regulation of Bcl-2 as well as the down-regulation of Bax and cytochrome c. We also found that lithium and VPA suppressed the Notch activation associated with the superoxide dismutase-1 (SOD1) mutation, and the combination of lithium and VPA produced a more robust effect than either agent alone. Our findings indicate that the Notch pathway plays a critical role in ALS, and the neuroprotective effects of lithium and VPA against mutant SOD1-mediated neuronal damage are at least partially dependent on their suppression of Notch activation.

Endoplasmic reticulum stress signaling in mammalian oocytes and embryos: life in balance

Mammalian oocytes and embryos are exquisitely sensitive to a wide range of insults related to physical stress, chemical exposure, and exposures to adverse maternal nutrition or health status. Although cells manifest specific responses to various stressors, many of these stressors intersect at the endoplasmic reticulum (ER), where disruptions in protein folding and production of reactive oxygen species initiate downstream signaling events. These signals modulate mRNA translation and gene transcription, leading to recovery, activation of autophagy, or with severe and prolonged stress, apoptosis. ER stress signaling has recently come to the fore as a major contributor to embryo demise. Accordingly, agents that modulate or inhibit ER stress signaling have yielded beneficial effects on embryo survival and long-term developmental potential. We review here the mechanisms of ER stress signaling, their connections to mammalian oocytes and embryos, and the promising indications that interventions in this pathway may provide new opportunities for improving mammalian reproduction and health.

PPAR gamma activation is neuroprotective in a Drosophila model of ALS based on TDP-43

Amyotrophic Lateral Sclerosis (ALS) is a progressive neuromuscular disease for which there is no cure. We have previously developed a Drosophila model of ALS based on TDP-43 that recapitulates several aspects of disease pathophysiology. Using this model, we designed a drug screening strategy based on the pupal lethality phenotype induced by TDP-43 when expressed in motor neurons. In screening 1200 FDA-approved compounds, we identified the PPARγ agonist pioglitazone as neuroprotective in Drosophila. Here, we show that pioglitazone can rescue TDP-43-dependent locomotor dysfunction in motor neurons and glia but not in muscles. Testing additional models of ALS, we find that pioglitazone is also neuroprotective when FUS, but not SOD1, is expressed in motor neurons. Interestingly, survival analyses of TDP or FUS models show no increase in lifespan, which is consistent with recent clinical trials. Using a pharmacogenetic approach, we show that the predicted Drosophila PPARγ homologs, E75 and E78, are in vivo targets of pioglitazone. Finally, using a global metabolomic approach, we identify a set of metabolites that pioglitazone can restore in the context of TDP-43 expression in motor neurons. Taken together, our data provide evidence that modulating PPARγ activity, although not effective at improving lifespan, provides a molecular target for mitigating locomotor dysfunction in TDP-43 and FUS but not SOD1 models of ALS in Drosophila. Furthermore, our data also identify several 'biomarkers' of the disease that may be useful in developing therapeutics and in future clinical trials.

Preconditioning with endoplasmic reticulum stress ameliorates endothelial cell inflammation

Endoplasmic Reticulum (ER) stress, caused by disturbance in ER homeostasis, has been implicated in several pathological conditions such as ischemic injury, neurodegenerative disorders, metabolic diseases and more recently in inflammatory conditions. Our present study aims at understanding the role of ER stress in endothelial cell (EC) inflammation, a critical event in the pathogenesis of acute lung injury (ALI). We found that preconditioning human pulmonary artery endothelial cells (HPAEC) to ER stress either by depleting ER chaperone and signaling regulator BiP using siRNA, or specifically cleaving (inactivating) BiP using subtilase cytotoxin (SubAB), alleviates EC inflammation. The two approaches adopted to abrogate BiP function induced ATF4 protein expression and the phosphorylation of eIF2α, both markers of ER stress, which in turn resulted in blunting the activation of NF-κB, and restoring endothelial barrier integrity. Pretreatment of HPAEC with BiP siRNA inhibited thrombin-induced IκBα degradation and its resulting downstream signaling pathway involving NF-κB nuclear translocation, DNA binding, phosphorylation at serine536, transcriptional activation and subsequent expression of adhesion molecules. However, TNFα-mediated NF-κB signaling was unaffected upon BiP knockdown. In an alternative approach, SubAB-mediated inactivation of NF-κB was independent of IκBα degradation. Mechanistic analysis revealed that pretreatment of EC with SubAB interfered with the binding of the liberated NF-κB to the DNA, thereby resulting in reduced expression of adhesion molecules, cytokines and chemokines. In addition, both knockdown and inactivation of BiP stimulated actin cytoskeletal reorganization resulting in restoration of endothelial permeability. Together our studies indicate that BiP plays a central role in EC inflammation and injury via its action on NF-κB activation and regulation of vascular permeability.

Hippocampal ER stress and learning deficits following repeated pyrethroid exposure

Endoplasmic reticulum (ER) stress is implicated as a significant contributor to neurodegeneration and cognitive dysfunction. Previously, we reported that the widely used pyrethroid pesticide deltamethrin causes ER stress-mediated apoptosis in SK-N-AS neuroblastoma cells. Whether or not this occurs in vivo remains unknown. Here, we demonstrate that repeated deltamethrin exposure (3 mg/kg every 3 days for 60 days) causes hippocampal ER stress and learning deficits in adult mice. Repeated exposure to deltamethrin caused ER stress in the hippocampus as indicated by increased levels of C/EBP-homologous protein (131%) and glucose-regulated protein 78 (96%). This was accompanied by increased levels of caspase-12 (110%) and activated caspase-3 (50%). To determine whether these effects resulted in learning deficits, hippocampal-dependent learning was evaluated using the Morris water maze. Deltamethrin-treated animals exhibited profound deficits in the acquisition of learning. We also found that deltamethrin exposure resulted in decreased BrdU-positive cells (37%) in the dentate gyrus of the hippocampus, suggesting potential impairment of hippocampal neurogenesis. Collectively, these results demonstrate that repeated deltamethrin exposure leads to ER stress, apoptotic cell death in the hippocampus, and deficits in hippocampal precursor proliferation, which is associated with learning deficits.