salubrinal and Disease-Models--Animal

Psoriasiform skin inflammation is the common chronic skin inflammatory disease with no effective clinical therapy. Salubrinal is a multifunctional molecule playing a protective role in several conditions. Recently, studies have reported that Salubrinal is a potential therapeutic agent for inflammatory diseases. However, the protective role of Salubrinal in psoriasis-like skin inflammation remains unknown. In this article, imiquimod (IMQ)-induced psoriasis models were established in wild-type mice to explore the role of Salubrinal in the development of psoriasis. As a result, the IMQ-induced mouse models exhibited typical skin inflammation, which was alleviated by the administration of Salubrinal. Furthermore, RAW264.7 macrophage was stimulated with Lipopolysaccharide(LPS) in the presence or absence of Salubrinal. LPS stimulation elevated the expression of various inflammatory biomarkers, while the administration of Salubrinal abolished the function of LPS in RAW264.7 macrophages. In addition, the activation of the nuclear factor-kappa B (NF-κB) signaling pathway in both the LPS-stimulated RAW264.7 macrophage and psoriasis mouse models was antagonized by the administration of Salubrinal. Collectively, Salubrinal might be considered as a promising therapeutic agent for psoriasis-like skin inflammation.

Topics: Animals; Cinnamates; Disease Models, Animal; Imiquimod; Inflammation; Macrophages; Male; Mice; Mice, Inbred C57BL; NF-kappa B; Protective Agents; Psoriasis; RAW 264.7 Cells; Signal Transduction; Skin; Thiourea; Tumor Necrosis Factor-alpha

The relationship between stress to endoplasmic reticulum (ER) and periodontitis has been known, and ER stress induced by Porphyromonas gingivalis results in the loss of alveolar bone. Salubrinal is a small synthetic compound and attenuates ER stress through inhibition of de-phosphorylation of eukaryotic translation initiation factor 2 alpha (eIF2α). In this study, we examined whether salubrinal attenuates periodontitis in a mouse model of experimental periodontal disease.. We evaluated loss of alveolar bone and attachment levels in periodontium using micro-computed tomography (μCT) and hematoxylin-eosin (HE) staining, respectively. Furthermore, we measured osteoclast numbers using tartrate-resistant acid phosphatase (TRAP) staining and osteoblast numbers using HE staining for bone resorption and for bone formation, respectively. To examine the inhibitory effects of salubrinal against pro-inflammatory cytokines, we measured TNF-α and IL1-β score in periodontium using immunohistostaining.. The results revealed that salubrinal suppressed loss of alveolar bone and attachment levels in periodontium induced by periodontitis. It decreased osteoclast numbers and increased osteoblasts. It also suppressed the expression levels of TNF-α in periodontium.. These results show that salubrinal alleviates periodontitis through suppression of alveolar bone resorption and the pro-inflammatory cytokine, and promotion of the bone formation. Since salubrinal has been shown to have these beneficial effects for periodontal disease, it may provide a novel therapeutic possibility for the disease.

Topics: Alveolar Bone Loss; Animals; Cell Count; Cinnamates; Disease Models, Animal; Endoplasmic Reticulum Stress; Interleukin-1beta; Male; Mice, Inbred C57BL; Osteoblasts; Periodontitis; Thiourea; Transcription Factor CHOP; Tumor Necrosis Factor-alpha; X-Ray Microtomography

Growth arrest and DNA damage-inducible protein 34 (GADD34), one of the key effectors of negative feedback loops, is induced by stress and subsequently attempts to restore homeostasis. It plays a critical role in response to DNA damage and endoplasmic reticulum stress. GADD34 has opposing effects on different stimulus-induced cell apoptosis events in many nervous system diseases, but its role in ischemic stroke is unclear. In this study, we evaluated the role of GADD34 and its distribution in a rat cerebral ischemic model. The results showed that GADD34 was increased in the cortex and contributed to brain injury in ischemic rats. Furthermore, treatment with a GADD34 inhibitor reduced the infarct volume, improved functional outcomes, and inhibited neuronal apoptosis in the cortical penumbra after ischemia. The role of GADD34 in ischemic stroke was associated with the dephosphorylation of eukaryotic translation initiation factor 2α (eIF2α) and phosphorylation of p53. In addition, the GADD34 level was increased in plasma exosomes of cerebral ischemic rats. These findings indicate that GADD34 could be a potential therapeutic target and biomarker for ischemic stroke.

Topics: Animals; Antigens, Differentiation; Biomarkers; Cinnamates; Disease Models, Animal; Eukaryotic Initiation Factor-2; Exosomes; Humans; Infarction, Middle Cerebral Artery; Male; Phosphorylation; Proto-Oncogene Proteins; Rats; Reperfusion Injury; Thiourea; Tumor Suppressor Protein p53

Perfusion abnormalities due to vasospasm remain a major cause of morbidity and mortality in subarachnoid hemorrhage (SAH). Despite a large number of clinical trials, therapeutic options with strong evidence for prevention and treatment of cerebral vasospasm are rare. In this study, we aimed to evaluate the neuroprotective effect of salubrinal (SLB) in endoplasmic reticulum stress-induced apoptosis, a catastrophic consequence of vasospasm.. Thirty-two Wistar albino rats were divided into 4 groups of 8 rats each: control group, SAH, SAH+SLB, and SAH+nimodipine (NMN). In the SAH+SLB group, intraperitoneal SLB (1 mg/kg dose) administered 30 minutes after establishment of SAH, and in the SAH+NMN group, intraperitoneal NMN (0.1 mg/kg dose) was also administered 30 minutes after SAH.. Higher total antioxidant status level, lower oxidative stress index, and significantly higher vascular endothelial growth factor-A (VEGF-A) level were detected in the SAH+SLB and SAH+NMN groups compared with the SAH group. There was a significant increase in eukaryotic translation initiation factor-2 alpha (elF2α) level in the SAH+SLB group compared with the SAH group. Histopathological evaluation revealed decrease in the subarachnoid hemorrhagic area, as well as in cortical edema and apoptotic bodies in the SAH+SLB and SAH+NMN groups. There was a significant decrease in caspase-3 staining in the SAH+SLB group, and the levels were significantly less in the SAH+NMN group than the SAH and SAH+SLB groups.. SLB, selective inhibitor of eIF2α dephosphorylation, and NMN, a calcium channel blocker, can ameliorate SAH-induced damage. Inhibition of eIF2α dephosphorylation and enhanced VEGF-A production with SLB may protect brain tissue from apoptosis.

Topics: Animals; Cinnamates; Disease Models, Animal; Endoplasmic Reticulum Stress; Neuroprotective Agents; Oxidative Stress; Rats; Rats, Wistar; Subarachnoid Hemorrhage; Thiourea; Vasospasm, Intracranial

Keratoconus (KC), a progressive, degenerative corneal disease, represents the second leading indication for corneal transplantation globally. We have previously demonstrated that components of the Integrated Stress Response (ISR) are upregulated in human keratoconic donor tissue, and treatment of normal tissue with ISR agonists attenuates collagen production. With no consistently accepted animal models available for translational KC research, we sought to establish an in vivo model based on ISR activation to elucidate its role in the development of the KC phenotype. Four-week-old female SD rats were treated with topical SAL003 formulated as a nanosuspension or vehicle every 48 h for four doses. Animals were subject to monitoring for ocular inflammation and discomfort before being euthanized at 1, 14, or 28 days after treatment was withdrawn. Schirmer's tear test, intraocular pressure, and body weight measurements were obtained at baseline and prior to euthanasia. Globes were subject to routine histopathology, immunohistochemistry for ATF4, and qPCR for Col1a1 expression. ANOVAs and Student's t tests were used to assess statistical significance (α = 0.05). SAL003 treatment did not produce any adverse ocular or systemic phenotype but did result in decreased keratocyte density. Col1a1 transcripts were reduced, corresponding to nuclear ATF4 expression within the axial cornea. In vivo topical treatment with a gel-formulated ISR agonist recapitulates key features of the activated ISR including nuclear ATF4 expression and decreased extracellular matrix (ECM) production. Exogenous ISR agonists may present one approach to establishing a rodent model for keratoconus, a charge essential for future evaluations of pathogenesis and therapeutic interventions.

Topics: Activating Transcription Factor 4; Animals; Cinnamates; Collagen Type I; Collagen Type I, alpha 1 Chain; Cornea; Corneal Keratocytes; Disease Models, Animal; Extracellular Matrix Proteins; Female; Keratoconus; Rats; Rats, Sprague-Dawley; Thiourea

When Zika virus emerged as a public health emergency there were no drugs or vaccines approved for its prevention or treatment. We used a high-throughput screen for Zika virus protease inhibitors to identify several inhibitors of Zika virus infection. We expressed the NS2B-NS3 Zika virus protease and conducted a biochemical screen for small-molecule inhibitors. A quantitative structure-activity relationship model was employed to virtually screen ∼138,000 compounds, which increased the identification of active compounds, while decreasing screening time and resources. Candidate inhibitors were validated in several viral infection assays. Small molecules with favorable clinical profiles, especially the five-lipoxygenase-activating protein inhibitor, MK-591, inhibited the Zika virus protease and infection in neural stem cells. Members of the tetracycline family of antibiotics were more potent inhibitors of Zika virus infection than the protease, suggesting they may have multiple mechanisms of action. The most potent tetracycline, methacycline, reduced the amount of Zika virus present in the brain and the severity of Zika virus-induced motor deficits in an immunocompetent mouse model. As Food and Drug Administration-approved drugs, the tetracyclines could be quickly translated to the clinic. The compounds identified through our screening paradigm have the potential to be used as prophylactics for patients traveling to endemic regions or for the treatment of the neurological complications of Zika virus infection.

Topics: Animals; Antiviral Agents; Artificial Intelligence; Chlorocebus aethiops; Disease Models, Animal; Drug Evaluation, Preclinical; High-Throughput Screening Assays; Immunocompetence; Inhibitory Concentration 50; Methacycline; Mice, Inbred C57BL; Protease Inhibitors; Quantitative Structure-Activity Relationship; Small Molecule Libraries; Vero Cells; Zika Virus; Zika Virus Infection

This study aimed to investigate the role of endoplasmic reticulum (ER) stress in polycystic ovary syndrome (PCOS) and the effect of salubrinal (SAL) on this role. Animals were divided into four groups as control, PCOS, PCOS+SAL and SAL. Weights and serum testosterone levels were increased in the PCOS group while serum LH and ATF4 expressions were decreased. Morphometrically, number of follicles with a diameter between 150 and 300 µm were declined and number of follicles larger than 300 µm as well as the percentage of cystic follicles (CFs) were increased. Immunoreactivities of GRP78 and p-eIF2α were decreased, whereas oxidative stress (OS) dependent PAR expression was increased. Ultrastructurally, the PCOS group had no ER enlargement which was observed in the control group, while there were mitochondrial damage in granulosa cells (GCs). Elevated OS levels did not induce but rather decreased ER stress in GCs, and SAL injection in the PCOS model was ineffective on searched parameters. Since ER stress plays roles in certain physiological processes, we suggest that inhibitors of ER stress may not be always useful for reproductive tissues.

Topics: Animals; Cinnamates; Disease Models, Animal; Endoplasmic Reticulum Chaperone BiP; Endoplasmic Reticulum Stress; Female; Mice; Mice, Inbred BALB C; Oxidative Stress; Polycystic Ovary Syndrome; Thiourea

Traumatic brain injury (TBI) is a complex injury that can cause severe disabilities and even death. TBI can induce secondary injury cascades, including but not limited to endoplasmic reticulum (ER) stress, apoptosis and autophagy. Although the investigators has previously shown that salubrinal, the selective phosphatase inhibitor of p-eIF2α, ameliorated neurologic deficits in murine TBI model, the neuroprotective mechanisms of salubrinal need further research to warrant the preclinical value. This study was undertaken to characterize the effects of salubrinal on cell death and neurological outcomes following TBI in mice and the potential mechanisms. In the current study, ER stress-related proteins including p-eIF2α, GRP78 and CHOP showed peak expressions both in the cortex and hippocampus from day 2 to day 3 after TBI, indicating ER stress was activated in our TBI model. Immunofluorescence staining showed that CHOP co-located NeuN-positive neuron, GFAP-positive astrocyte, Iba-1-positive microglia, CD31-positive vascular endothelial cell and PDGFR-β-positive pericyte in the cortex on day 2 after TBI, and these cells mentioned above constitute the neurovascular unit (NVU). We also found TBI-induced plasmalemma permeability, motor dysfunction, spatial learning and memory deficits and brain lesion volume were alleviated by continuous intraperitoneal administration of salubrinal post TBI. To investigate the underlying mechanisms further, we determined that salubrinal suppressed the expression of ER stress, autophagy and apoptosis related proteins on day 2 after TBI. In addition, salubrinal administration decreased the number of CHOP+/TUNEL+ and CHOP+/LC3+ cells on day 2 after TBI, detected by immunofluorescence. In conclusion, these data imply that salubrinal treatment improves morphological and functional outcomes caused by TBI in mice and these neuroprotective effects may be associated with inhibiting apoptosis, at least in part by suppressing ER stress-autophagy pathway.

Topics: Animals; Apoptosis; Autophagy; Brain Injuries, Traumatic; Cinnamates; Disease Models, Animal; Endoplasmic Reticulum Chaperone BiP; Endoplasmic Reticulum Stress; Male; Mice; Mice, Inbred ICR; Neuroprotective Agents; Thiourea

Ischemic stroke is one of the most important causes of death and disability worldwide. Subroutines underlying cell death after stroke are largely unknown despite their importance in the design of novel therapies for this pathology. Necroptosis, a recently described form of regulated cell death, has been related with inflammation and, in some models, with endoplasmic reticulum (ER) stress. We hypothesize that alleviation of ER stress following a salubrinal treatment will reduce the ischemic-dependent necroptosis. To probe the hypothesis, we measured, at 48 and 72 h after transient global cerebral ischemia in rat, in cerebral cortex and cornu ammonis 1, the main hallmarks of necroptosis: mRNA levels and phosphorylation of mixed lineage kinase domain like pseudokinase as well as receptor interacting serine/threonine protein kinase 3, along the years 2017-2018. Selective neuronal loss after 7 days of the ischemic insult, and other markers related with the inflammatory response were also measured. This study shows that necroptosis in cerebral cortex can be detected after 72 h of the insult and seems to be elicited before 48 h of reperfusion. The type of necroptosis here observed seems to be tumor necrosis factor receptor 1 independent. Necroptotic response is less evident in the cornu ammonis 1 hippocampal area than in cerebral cortex. The treatment with salubrinal administered 1 and 24 h after the ischemia, decreased the necroptotic marker levels and reduced the areas of selective neuronal loss, supporting the presence of ischemic-dependent necroptosis, and the notion that ER stress is involved in the necroptotic response. Open Science: This manuscript was awarded with the Open Materials Badge For more information see: https://cos.io/our-services/open-science-badges/.

Topics: Animals; Brain Ischemia; Cell Survival; Cerebral Cortex; Cinnamates; Disease Models, Animal; Male; Necroptosis; Neuroprotective Agents; Rats; Rats, Sprague-Dawley; Thiourea

Classic Galactosemia is an autosomal recessive disorder caused by deleterious mutations in the GALT gene, which encodes galactose-1 phosphate uridylyltransferase enzyme (GALT: EC 2.7.7.12). Recent studies of primary skin fibroblasts isolated from the GalT-deficient mice demonstrated a slower growth rate, a higher level of endoplasmic reticulum (ER) stress, and down-regulation of the Phosphoinositide 3 kinase/Protein kinase B (PI3K/Akt) signaling pathway. In this study, we compared the expression levels of the PI3K/Akt signaling pathway in normal and GalT-deficient mouse tissues. In mutant mouse ovaries, phospho-Akt [pAkt (Ser473)] and pGsk3β were reduced by 62.5% and 93.5%, respectively (p<0.05 versus normal controls). In mutant cerebella, pAkt (Ser473) and pGsk3β were reduced by 62%, 50%, respectively (p<0.05). To assess the role of ER stress in the down-regulation of PI3K/Akt signaling, we examined if administration of Salubrinal, a chemical compound that alleviates ER stress, to GalT-deficient fibroblasts and animals could normalize the pathway. Our results demonstrated that Salubrinal effectively reversed the down-regulated PI3K/Akt signaling pathway in the mutant cells and animals to levels close to those of their normal counterparts. Moreover, we revealed that Salubrinal can significantly slow down the loss of Purkinje cells in the cerebella, as well as the premature loss of primordial ovarian follicles in young mutant mice. These results open the door for a new therapeutic approach for the patients with Classic Galactosemia.

Topics: Animals; Cinnamates; Disease Models, Animal; Down-Regulation; Endoplasmic Reticulum Stress; Female; Fibroblasts; Galactosemias; Mice; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Purkinje Cells; Signal Transduction; Thiourea; UTP-Hexose-1-Phosphate Uridylyltransferase

Following a central nervous system (CNS) injury, restoration of the blood-brain barrier (BBB) integrity is essential for recovering homeostasis. When this process is delayed or impeded, blood substances and cells enter the CNS parenchyma, initiating an additional inflammatory process that extends the initial injury and causes so-called secondary neuronal loss. Astrocytes and profibrotic mesenchymal cells react to the injury and migrate to the lesion site, creating a new glia limitans that restores the BBB. This process is beneficial for the resolution of the inflammation, neuronal survival, and the initiation of the healing process. Salubrinal is a small molecule with neuroprotective properties in different animal models of stroke and trauma to the CNS. Here, we show that salubrinal increased neuronal survival in the neighbourhood of a cerebral cortex stab injury. Moreover, salubrinal reduced cortical blood leakage into the parenchyma of injured animals compared with injured controls. Adjacent to the site of injury, salubrinal induced immunoreactivity for platelet-derived growth factor subunit B (PDGF-B), a specific mitogenic factor for mesenchymal cells. This effect might be responsible for the increased immunoreactivity for fibronectin and the decreased activation of microglia and macrophages in injured mice treated with salubrinal, compared with injured controls. The immunoreactivity for PDGF-B colocalized with neuronal nuclei (NeuN), suggesting that cortical neurons in the proximity of the injury were the main source of PDGF-B. Our results suggest that after an injury, neurons play an important role in both, the healing process and the restoration of the BBB integrity. J. Cell. Physiol. 232: 1501-1510, 2017. © 2016 Wiley Periodicals, Inc.

Topics: Animals; Astrocytes; Blood-Brain Barrier; Brain Injuries; Calcium-Binding Proteins; Cell Survival; Cerebral Cortex; Cinnamates; Disease Models, Animal; Evans Blue; Fibronectins; Male; Mice, Inbred C57BL; Microfilament Proteins; Models, Biological; Neurons; Neuroprotection; Platelet-Derived Growth Factor; Signal Transduction; Thiourea; Transforming Growth Factor beta; Wounds, Stab

Suppressed adaptive immune function is one of the major concerns responsible for the development of opportunistic infections and subsequent sepsis with high mortality in severe burns. Endoplasmic reticulum stress (ERS) is the endogenous self-protective mechanism, and it plays an important role in almost every process of living by regulating the balance between homeostasis and apoptosis. The current study investigated the involvement of ERS in the pathogenesis of dysfunction of dendritic cells (DCs) in burn mice. Our results show a significant ERS response in splenic DC after burn injury. Treatment with salubrinal (Sal, reported to protect cells against ERS-induced apoptosis.) decrease the apoptotic rate of DC induced by burns, and promote maturation and activation of DC, as well as the ability to promote T cell proliferation and polarization towards Th1 immunity (all P<0.05). Gene silence of XBP-1 (key molecular in ERS response) results in the increased apoptosis and suppressed phenotypical maturation of splenic DC in burn mice. These results show that the excessive ERS is essential for immunosuppression during severe thermal injury. XBP-1 plays a pivotal role in DC functional immunomodulation in burn mice. Inhibition of apoptotic ERS response benefits mice from major burns.

Topics: Adaptive Immunity; Animals; Apoptosis; Burns; Cells, Cultured; Cinnamates; Coculture Techniques; Cytokines; Dendritic Cells; Disease Models, Animal; Endoplasmic Reticulum Stress; Lymphocyte Activation; Male; Mice, Inbred BALB C; Phenotype; RNA Interference; Severity of Illness Index; Spleen; Th1 Cells; Thiourea; Time Factors; X-Box Binding Protein 1

Pathological hypertrophy of the heart is closely associated with endoplasmic reticulum stress (ERS), leading to maladaptations such as myocardial fibrosis, induction of apoptosis, and cardiac dysfunctions. Salubrinal is a known selective inhibitor of protein phosphatase 1 (PP1) complex involving dephosphorylation of phospho-eukaryotic translation initiation factor 2 subunit (p-eIF2)-α, the key signaling process in the ERS pathway. In this study, the effects of salubrinal were examined on cardiac hypertrophy using the mouse model of transverse aortic constriction (TAC) and cell model of neonatal rat ventricular myocytes (NRVMs). Treatment of TAC-induced mice with salubrinal (0.5 mg·kg

Topics: Animals; Cardiomegaly; Cinnamates; Disease Models, Animal; Endoplasmic Reticulum Stress; Male; Mice; Mice, Inbred C57BL; Rats; Thiourea

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.

Topics: Animals; Brain Injuries, Traumatic; Cinnamates; Disease Models, Animal; Encephalitis; Endoplasmic Reticulum Stress; Frontal Lobe; Impulsive Behavior; Male; Neuroprotective Agents; Oxidative Stress; Rats; Rats, Sprague-Dawley; Thiourea

Excessive mechanical loads on the temporomandibular joint (TMJ) can cause mandibular cartilage degradation and subchondral bone erosion, but the treatment of these conditions remains challenging. Salubrinal, which target eukaryotic translation initiation factor 2 alpha, has been shown to have multiple beneficial effects on skeletal tissue. Here, we examined the effect of a Salubrinal injection on the mandibular cartilage and subchondral bone of the TMJ under various compressive stresses. We conducted in vivo analyses in rat models using various compressive stresses (40 g and 80 g), and we observed time-related degeneration and pathological changes in the cartilage and subchondral bone of the TMJ at days 1, 3 and 7 through histological measurements, subcellular observation, and changes in proliferation and apoptosis. After the Salubrinal injection, the thickness of the cartilage recovered, and the pathological change was alleviated. In the Salubrinal/light (Sal/light) compressive stress group, the drug altered the proliferation and apoptosis of chondrocytes most significantly at day 1. In the Salubrinal/heavy (Sal/heavy) compressive stress group, the drug increased the proliferation of chondrocytes most significantly at day 1 and reduced the apoptosis of chondrocytes most significantly at day 7. Salubrinal also increased the area of the bone trabeculae and suppressed inflammatory responses and pathological change in the subchondral bone of the TMJ. Together, these results indicate that the administration of Salubrinal reduces apoptosis and strengthens the proliferation of chondrocyte to varying degrees at days 1, 3 and 7 under various compressive mechanical stresses, both of which contribute to the recovery of cartilage thickness and the alleviation of pathological change. Salubrinal also suppresses inflammatory responses and pathological change in the subchondral bone of the TMJ.

Topics: Animals; Apoptosis; Bone and Bones; Cartilage; Cell Proliferation; Chondrocytes; Cinnamates; Compressive Strength; Computer Simulation; Disease Models, Animal; Immunohistochemistry; Male; Mandible; Microscopy, Electron, Transmission; Rats; Rats, Sprague-Dawley; Stress, Mechanical; Temporomandibular Joint; Thiourea

The aim of the present study was to examine the role of eIF2α in cardiomyocyte apoptosis and evaluate the cardioprotective role of salubrinal in a rat myocardial infarction (MI) model. Rat left anterior descending coronary arteries were ligated and the classical proteins involved in the endoplasmic reticulum stress (ERS)-induced apoptotic pathway were analyzed using quantitative polymerase chain reaction and western blot analysis. Salubrinal was administered to the rats and cardiomyocyte apoptosis and infarct size were evaluated by a specific staining method. Compared with the sham surgery group, the rate of cardiomyocyte apoptosis in the MI group was increased with the development of the disease. It was also demonstrated that the mRNA and protein levels of GRP78, caspase-12, CHOP and the protein expression of p-eIF2α were increased in the MI group. Furthermore, the results showed that treatment with salubrinal can decrease cardiomyocyte apoptosis and infarct size by increasing eIF2α phosphorylation and decreasing the expression of caspase-12 and CHOP. The present study suggests that salubrinal protects against ER stress-induced rat cadiomyocyte apoptosis via suppressing the dephosphorylation of eIF2α in the ERS-associated pathway.

Topics: Animals; Apoptosis; Cardiotonic Agents; Caspase 12; Cinnamates; Disease Models, Animal; Disease Progression; Endoplasmic Reticulum Stress; Eukaryotic Initiation Factor-2; Gene Expression Regulation; Heat-Shock Proteins; Male; Myocardial Infarction; Myocytes, Cardiac; Phosphorylation; Rats; Rats, Wistar; Severity of Illness Index; Signal Transduction; Thiourea; Transcription Factor CHOP

Previous studies have indicated that endoplasmic reticulum stress participates in and mediates liver injury and apoptosis in brain-dead (BD) rats. In this study, we observed the effect of salubrinal (Sal, Sigma, USA) on liver cells in BD rats and explored its relevant mechanisms.. Thirty Sprague-Dawley rats were equally randomized into three groups: BD group, Sal group, and DMSO group. The BD models were established by increasing intracranial pressure in a modified, slow, and intermittent way. In the drug groups, Sal was administered 1 h before the induction of BD. After modeling was completed, the blood and liver samples were harvested. CHOP and Caspase-12 mRNA expression was detected using quantitative polymerase chain reaction. PKR-like ER kinase (PERK), P-eukaryotic translation initiation factor 2α (eIF2α), eIF2α, CHOP and caspase-12 expression was detected using western blotting (WB). CHOP and caspase-12 distribution and expression in liver tissues were determined using immunohistochemistry (IHC). Alanine aminotransferase and aspartate aminotransferase level were detected using an automatic biochemical analyzer. Hepatic cell apoptosis was detected using TUNEL. The results were analyzed using Quantity-one v4.62 software (Bio-Rad, USA).. CHOP and caspase-12 expression and PERK, eIF2α, and P-eIF2α protein expression showed no significant difference between BD group and DMSO group. Compared with BD group, Sal group had a significantly higher P-eIF2C level and a lower P-PERK level 2 h and 6 h after BD (P < 0.05). However, eIF2α expression showed no significant difference (P > 0.05). After the Sal treatment, CHOP and caspase-12 mRNA expression significantly decreased 4 h after BD (P < 0.05). WB and IHC indicated that CHOP and caspase-12 expression also significantly decreased after Sal treatment. Sal was associated with improved liver function and decreased hepatic cell apoptosis.. Sal can significantly reduce apoptosis in hepatic cells of BD rats. This protective effect may be achieved via the PERK-eIF2α signaling pathway.

Topics: Animals; Apoptosis; Blotting, Western; Brain Death; Caspase 12; Cinnamates; Disease Models, Animal; Endoplasmic Reticulum Stress; Eukaryotic Initiation Factor-2; Immunohistochemistry; Liver; Male; Rats; Rats, Sprague-Dawley; Real-Time Polymerase Chain Reaction; Thiourea; Transcription Factor CHOP

To investigate the efficacy of 2-phenyl-APB-144 (APB)-induced retinopathy in a rat model and its underlying mechanisms, with a particular focus on retinal pigment epithelium (RPE) degeneration.. Electroretinograms (ERGs) were evaluated in APB-administered rats. In ARPE-19 cells, cathepsin, and autophagy marker LC3 were analyzed by western blotting or immunohistochemistry. Organelle pH alterations were detected by Acridine Orange Staining. Endoplasmic reticulum stress-dependent or -independent cell death signaling was analyzed by reporter gene assays of activating transcription factor 4 (ATF4), immunoglobulin heavy-chain binding protein (BiP), inositol-requiring enzyme 1α (IRE1α), quantitative reverse transcription-polymerase chain reaction of CHOP mRNA, and the effects of pharmacological eukaryotic initiation factor 2α (eIF2α) dephosphorylation inhibitor, Salubrinal. The pharmacological effects of Salubrinal were examined by fluorophotometry, electrophysiology, and histopathology.. APB-induced ERG amplitude reduction and fluorescein permeability enhancement into the vitreous body of rats were determined. In ARPE-19 cells, APB-induced organelle pH alterations, imbalances of procathepsin and cathepsin expression, the time-dependent accumulation of LC3-II, and the translational activation of ATF4 were determined. Salubrinal protected against APB-induced cell death and inhibited ATF4 downstream factor CHOP mRNA induction. In APB-induced rat retinopathy, systemic Salubrinal alleviated the enhanced fluorescein permeability into the vitreous body from the RPE, the reductions in ERG amplitudes, and RPE degeneration.. Organelle pH alterations and autophagy impairments are involved in APB-induced RPE cell death. Inhibition of eIF2α dephosphorylation protected the RPE in vivo and in vitro. These findings suggested that APB-induced retinopathy is a valuable animal model for exploring the mechanism of RPE-driven retinopathy.

Topics: Animals; Autophagy; Biphenyl Compounds; Blotting, Western; Cathepsins; Cell Line; Cinnamates; Disease Models, Animal; Electroretinography; Endoplasmic Reticulum Stress; Humans; Hydrogen-Ion Concentration; Male; Microtubule-Associated Proteins; Organelles; Rats; Rats, Inbred BN; Retinal Diseases; Retinal Pigment Epithelium; Reverse Transcriptase Polymerase Chain Reaction; Thiourea

Obstructive sleep apnea hypopnea syndrome (OSAHS) in children is associated with multiple system morbidities. Cognitive dysfunction as a result of central nervous system complication has been reported in children with OSAHS. However, the underlying mechanisms are poorly understood. Endoplasmic reticulum stress (ERS)-related apoptosis plays an important role in various diseases of the central nervous system, but very little is known about the role of ERS in mediating pathophysiological reactions to cognitive dysfunction in OSAHS. Chronic intermittent hypoxia (CIH) exposures, modeling OSAHS, across 2 and 4weeks in growing rats made more reference memory errors, working memory errors and total memory errors in the 8-Arm radial maze task, increased significantly TUNEL positive cells, upregulated the unfolded protein response in the hippocampus and prefrontal cortex as evidenced by increased phosphorylation of PKR-like endoplasmic reticulum kinase, inositol-requiring enzyme l and some downstream products. A selective inhibitor of eukaryotic initiation factor-2a dephosphorylation, salubrinal, prevented C/EBP-homologous protein activation in the hippocampus and prefrontal cortex throughout hypoxia/reoxygenation exposure. Our findings suggest that ERS mediated cell apoptosis may be one of the underlying mechanisms of cognitive dysfunction in OSAHS children. Further, a specific ERS inhibitor Salubrinal should be tested for neuroprotection against CIH-induced injury.

Topics: Age Factors; Aging; Animals; Blood Pressure; Brain Injuries; Cinnamates; Disease Models, Animal; Endoplasmic Reticulum; Endoplasmic Reticulum Stress; Hippocampus; Hypoxia; Learning Disabilities; Male; Maze Learning; Oligopeptides; Prefrontal Cortex; Rats; Rats, Sprague-Dawley; Thiourea; Time Factors; Transcription Factors

Endoplasmic reticulum (ER) stress in the intestine is closely associated with the development of inflammatory bowel disease (IBD). However, the role of the protein kinase RNA-like ER kinase in this disease is not fully known. We studied whether an inhibitor of the dephosphorylation of eukaryotic initiation factor 2α, salubrinal, improves murine experimental colitis through the amelioration of ER stress.. Colitis was induced by the administration of 3% dextran sulfate sodium (DSS) for 5 days. Mice were injected salubrinal intraperitoneally from the commencement of DSS treatment and were sacrificed on day 10. The severity of colitis was evaluated histologically using a scoring system.Myeloperoxidase activity and the expression of proinflammatory cytokine genes in the colon were analyzed. The expression levels of ER stress-related proteins were evaluated by Western blotting.. The administration of salubrinal significantly attenuated body weight loss and improved colitis, as assessed histologically. The elevation of myeloperoxidase activity and the expression of proinflammatory cytokine genes were suppressed in salubrinal-treated mice. The expression of glucose-regulated protein 78, activating translation factor 4, and heat-shock protein 70 was elevated in mice treated with salubrinal.. The amelioration of ER stress may be a therapeutic target for the treatment of IBD.

Topics: Animals; Cinnamates; Colitis; Colon; Dextran Sulfate; Disease Models, Animal; DNA-Binding Proteins; eIF-2 Kinase; Endoplasmic Reticulum Chaperone BiP; Endoplasmic Reticulum Stress; Eukaryotic Initiation Factor-2; Heat-Shock Proteins; HSP70 Heat-Shock Proteins; Injections, Intraperitoneal; Interleukins; Male; Mice; Mice, Inbred C57BL; Peroxidase; Regulatory Factor X Transcription Factors; RNA, Messenger; Thiourea; Transcription Factors; Tumor Necrosis Factor-alpha; Weight Loss

Activating transcription factor 5 (ATF5) is a basic-leucine-zipper transcription factor of the ATF/CREB family. The Atf5 gene generates two transcripts, Atf5α and Atf5β, of which Atf5α is known to be selectively translated upon endoplasmic reticulum stress response in non-neuronal cells. ATF5 is highly expressed in the developing brain where it modulates proliferation of neural progenitor cells. These cells show a high level of ATF5 that has to decrease to allow them to differentiate into mature neurons or glial cells. This has led to the extended notion that differentiated neural cells do not express ATF5 unless they undergo tumourigenic transformation. However, no systematic analysis of the distribution of ATF5 in adult brain or of its potential role in neuronal endoplasmic reticulum stress response has been reported. By immunostaining here we confirm highest ATF5 levels in neuroprogenitor cells of the embryonic and adult subventricular zone but also found ATF5 in a large variety of neurons in adult mouse brain. By combining Atf5 in situ hybridization and immunohistochemistry for the neuronal marker NeuN we further confirmed Atf5 messenger RNA in adult mouse neurons. Quantitative reverse transcriptase polymerase chain reaction demonstrated that Atf5α is the most abundant transcript in adult mouse encephalon and injection of the endoplasmic reticulum stress inducer tunicamycin into adult mouse brain increased neuronal ATF5 levels. Accordingly, ATF5 levels increased in hippocampal neurons of a mouse model of status epilepticus triggered by intra-amygdala injection of kainic acid, which leads to abnormal hippocampal neuronal activity and endoplasmic reticulum stress. Interestingly, ATF5 upregulation occurred mainly in hippocampal neuronal fields that do not undergo apoptosis in this status epilepticus model such as CA1 and dentate gyrus, thus suggesting a neuroprotective role. This was confirmed in a primary neuronal culture model in which ATF5 overexpression resulted in decreased endoplasmic reticulum stress-induced apoptosis and the opposite result was achieved by Atf5 RNA interference. Furthermore, in vivo administration of the eIF2α phosphatase inhibitor salubrinal resulted in increased ATF5 hippocampal levels and attenuated status epilepticus-induced neuronal death in the vulnerable CA3 subfield. In good agreement with the neuroprotective effect of increased ATF5, we found that apoptosis-resistant epileptogenic foci from patients with temporal lobe ep

Topics: Activating Transcription Factors; Animals; Apoptosis; Cinnamates; Disease Models, Animal; Endoplasmic Reticulum Stress; Humans; Mice; Mice, Inbred C57BL; Neurons; Neuroprotective Agents; Status Epilepticus; Thiourea

C. elegans and D. rerio expressing mutant TAR DNA Binding Protein 43 (TDP-43) are powerful in vivo animal models for the genetics and pharmacology of amyotrophic lateral sclerosis (ALS). Using these small-animal models of ALS, we previously identified methylene blue (MB) as a potent suppressor of TDP-43 toxicity. Consequently here we investigated how MB might exert its neuroprotective properties and found that it acts through reduction of the endoplasmic reticulum (ER) stress response. We tested other compounds known to be active in the ER unfolded protein response in worms and zebrafish expressing mutant human TDP-43 (mTDP-43). We identified three compounds: salubrinal, guanabenz and a new structurally related compound phenazine, which also reduced paralysis, neurodegeneration and oxidative stress in our mTDP-43 models. Using C. elegans genetics, we showed that all four compounds act as potent suppressors of mTDP-43 toxicity through reduction of the ER stress response. Interestingly, these compounds operate through different branches of the ER unfolded protein pathway to achieve a common neuroprotective action. Our results indicate that protein-folding homeostasis in the ER is an important target for therapeutic development in ALS and other TDP-43-related neurodegenerative diseases.

Topics: Analysis of Variance; Animals; Animals, Genetically Modified; Caenorhabditis elegans; Caenorhabditis elegans Proteins; Cinnamates; Disease Models, Animal; DNA-Binding Proteins; Endoplasmic Reticulum Stress; Escape Reaction; Green Fluorescent Proteins; Guanabenz; Humans; Microinjections; Movement Disorders; Mutation; Neurons; Neurotoxicity Syndromes; Phenazines; Reactive Oxygen Species; RNA, Messenger; Thiourea; Time Factors; Touch; Zebrafish; Zebrafish Proteins

The endoplasmic reticulum (ER) stress response (ERSR) is activated to maintain protein homeostasis or induce apoptosis in the ER in response to distinct cellular insults including hypoxia, inflammation, and oxidative damage. Recently, we showed ERSR activation in a mouse model of a contusive spinal cord injury (SCI) and an improved hindlimb locomotor function following SCI when the pro-apoptotic arm of ERSR was genetically inhibited. The objective of the current study was to explore if the pharmacological enhancement of the homeostatic arm of the ERSR pathway can improve the functional outcome after SCI. Salubrinal enhances the homeostatic arm of the ERSR by increasing phosphorylation of eIF2α. Salubrinal significantly enhanced the levels of phosphorylated eIF2α protein and modulated the downstream ERSR effectors assessed at the lesion epicenter 6h post-SCI. Hindlimb locomotion showed significant improvement in animals treated with salubrinal. Treadmill-based-gait assessment showed a significant increase in maximum speed of coordinated walking and a decrease in rear stance time and stride length in salubrinal-treated animals. This improved functional recovery corresponded with increased white matter sparing and decreased oligodendrocyte apoptosis. In addition, salubrinal protected cultured mouse oligodendrocyte progenitor cells against the ER stress-inducing toxin tunicamycin. These data suggest that boosting the homeostatic arm of the ERSR reduces oligodendrocyte loss after traumatic SCI and support the contention that pharmacological targeting of the ERSR after CNS trauma is a therapeutically viable approach.

Topics: Activating Transcription Factor 4; Animals; Animals, Newborn; Cerebral Cortex; Cinnamates; Disease Models, Animal; Endoplasmic Reticulum; Endoplasmic Reticulum Chaperone BiP; Gait Disorders, Neurologic; Gene Expression Regulation; Glutamate-Ammonia Ligase; Heat-Shock Proteins; Homeostasis; Locomotion; Mice; Mice, Inbred C57BL; Mice, Knockout; Myelin Basic Protein; Nerve Fibers, Myelinated; Oligodendroglia; Phosphorylation; Protein Phosphatase 1; Recovery of Function; Spinal Cord Injuries; Thiourea; Tunicamycin

Osteoporosis is a skeletal disease leading to an increased risk of bone fracture. Using a mouse osteoporosis model induced by administration of a receptor activator of nuclear factor kappa-B ligand (RANKL), salubrinal was recently reported as a potential therapeutic agent. To evaluate the role of salubrinal in cellular fates as well as migratory and adhesive functions of osteoclast/osteoblast precursors, we examined the development of primary bone marrow-derived cells in the presence and absence of salubrinal. We addressed a question: are salubrinal's actions more potent to the cells isolated from the osteoporotic mice than those isolated from the control mice?. Using the RANKL-injected and control mice, bone marrow-derived cells were harvested. Osteoclastogenesis was induced by macrophage-colony stimulating factor and RANKL, while osteoblastogenesis was driven by dexamethasone, ascorbic acid, and β-glycerophosphate.. The results revealed that salubrinal suppressed the numbers of colony forming-unit (CFU)-granulocyte/macrophages and CFU-macrophages, as well as formation of mature osteoclasts in a dosage-dependent manner. Salubrinal also suppressed migration and adhesion of pre-osteoclasts and increased the number of CFU-osteoblasts. Salubrinal was more effective in exerting its effects in the cells isolated from the RANKL-injected mice than the control. Consistent with cellular fates and functions, salubrinal reduced the expression of nuclear factor of activated T cells c1 (NFATc1) as well as tartrate-resistant acid phosphatase.. The results support the notion that salubrinal exhibits significant inhibition of osteoclastogenesis as well as stimulation of osteoblastogenesis in bone marrow-derived cells, and its efficacy is enhanced in the cells harvested from the osteoporotic bone samples.

Topics: Animals; Bone Density Conservation Agents; Bone Marrow Cells; Cell Adhesion; Cell Movement; Cell Survival; Cells, Cultured; Cinnamates; Disease Models, Animal; Dose-Response Relationship, Drug; Female; Mice; Mice, Inbred C57BL; Osteoblasts; Osteoclasts; Osteoporosis; Stem Cells; Thiourea

Bone loss in osteoporosis, commonly observed in postmenopausal women and the elderly, is caused by an imbalance in activities of bone-forming osteoblasts and bone-resorbing osteoclasts. To treat osteoporosis and increase bone mineral density (BMD), physical activities and drugs are often recommended. Complex systems dynamics prevent an intuitive prediction of treatment strategies, and little is known about an optimal sequence for the combinatorial use of available treatments. In this study, the authors built a mathematical model of bone remodelling and developed a treatment strategy for mechanical loading and salubrinal, a synthetic chemical agent that enhances bone formation and prevents bone resorption. The model formulated a temporal BMD change of a mouse's whole skeleton in response to ovariectomy, mechanical loading and administration of salubrinal. Particle swarm optimisation was employed to maximise a performance index (a function of BMD and treatment cost) to find an ideal sequence of treatment. The best treatment was found to start with mechanical loading followed by salubrinal. As treatment costs increased, the sequence started with no treatment and usage of salubrinal became scarce. The treatment strategy will depend on individual needs and costs, and the proposed model is expected to contribute to the development of personalised treatment strategies.

Topics: Algorithms; Animals; Bone and Bones; Bone Density; Bone Remodeling; Bone Resorption; Cinnamates; Disease Models, Animal; Female; Mice; Mice, Inbred C57BL; Models, Biological; Osteoblasts; Osteoclasts; Osteoporosis; Stress, Mechanical; Systems Biology; Thiourea; Time Factors

Nuclear factor-κB (NF-κB) ligand (RANKL) was shown to induce osteoclast differentiation by increasing the expression of c-Fos, NFATc1 and TRAP. Salubrinal treatment to bone marrow macrophage (BMM) cells, however, significantly blocked NFATc1 expression and osteoclast differentiation by RANKL. Overexpression of NFATc1 further confirmed that NFATc1 is a key factor affected by salubrinal in osteoclast differentiation by RANKL. Unexpectedly, NFATc1 and c-Fos mRNA expressions were not affected by salubrinal, implicating that NFATc1 expression is regulated at a translational stage. In support of this, salubrinal increased the phosphorylation of a translation factor eIF2α, decreasing the global protein synthesis including NFATc1. In contrast, a phosphorylation mutant plasmid pLenti-eIF2α-S51A restored RANKL-induced NFATc1 expression and osteoclast differentiation even in the presence of salubrinal. Furthermore, knockdown of ATF4 significantly reduced salubrinal-induced osteoblast differentiation as evidenced by decreased calcium accumulation and lowered expressions of the osteoblast differentiation markers, alkaline phosphatase and RANKL in MC3T3-E1 osteoblast cells. Salubrinal treatment to co-cultured BMM and MC3T3-E1 cells also showed reduction of osteoclast differentiation. Finally, salubrinal efficiently blocked osteoporosis in mice model treated with RANKL as evidenced by elevated bone mineral density (BMD) and other osteoporosis factors. Collectively, our data indicate that salubrinal could affect the differentiation of both osteoblast and osteoclast, and be developed as an excellent anti-osteoporosis drug. In addition, modulation of ATF4 and NFATc1 expressions through eIF2α phosphorylation could be a valuable target for the treatment of osteoporosis.

Topics: Activating Transcription Factor 4; Animals; Bone Marrow Cells; Calcium; Cell Differentiation; Cells, Cultured; Cinnamates; Coculture Techniques; Disease Models, Animal; Eukaryotic Initiation Factor-2; Femur; Mice; NFATC Transcription Factors; Osteoblasts; Osteoclasts; Osteoporosis; Phosphorylation; Radiography; RANK Ligand; RNA Interference; RNA, Small Interfering; Signal Transduction; Thiourea; Tibia

Recent studies have suggested that autophagy plays a prosurvival role in ischemic preconditioning (IPC). This study was taken to assess the linkage between autophagy and endoplasmic reticulum (ER) stress during the process of IPC. The effects of IPC on ER stress and neuronal injury were determined by exposure of primary cultured murine cortical neurons to 30 min of OGD 24 h prior to a subsequent lethal OGD. The effects of IPC on ER stress and ischemic brain damage were evaluated in rats by a brief ischemic insult followed by permanent focal ischemia (PFI) 24 h later using the suture occlusion technique. The results showed that both IPC and lethal OGD increased the LC3-II expression and decreased p62 protein levels, but the extent of autophagy activation was varied. IPC treatment ameliorated OGD-induced cell damage in cultured cortical neurons, whereas 3-MA (5-20 mM) and bafilomycin A 1 (75-150 nM) suppressed the neuroprotection induced by IPC. 3-MA, at the dose blocking autophagy, significantly inhibited IPC-induced HSP70, HSP60 and GRP78 upregulation; meanwhile, it also aggregated the ER stress and increased activated caspase-12, caspase-3 and CHOP protein levels both in vitro and in vivo models. The ER stress inhibitor Sal (75 pmol) recovered IPC-induced neuroprotection in the presence of 3-MA. Rapamycin 50-200 nM in vitro and 35 pmol in vivo 24 h before the onset of lethal ischemia reduced ER stress and ischemia-induced neuronal damage. These results demonstrated that pre-activation of autophagy by ischemic preconditioning can boost endogenous defense mechanisms to upregulate molecular chaperones, and hence reduce excessive ER stress during fatal ischemia.

Topics: Adenine; Animals; Apoptosis; Autophagy; Brain Ischemia; Caspase 12; Caspase 3; Cells, Cultured; Cerebral Cortex; Cinnamates; Cytoprotection; Disease Models, Animal; Endoplasmic Reticulum; Endoplasmic Reticulum Chaperone BiP; Endoplasmic Reticulum Stress; Glucose; Heat-Shock Proteins; HSP70 Heat-Shock Proteins; Ischemic Preconditioning; Male; Mice; Neurons; Oxygen; Rats; Rats, Sprague-Dawley; Sirolimus; Thiourea; Transcription Factor CHOP

The endoplasmic reticulum(ER) stress plays a vital role in mediating ischemic neuronal cell death. However, very little is known about the role of ER stress in mediating pathophysiological reactions to acute brain injuries. An attempt was therefore made to assess the role of cerebral ischemia/reperfusion (I/R) induced ER stress and its modulation on outcome of ischemic insult. Focal cerebral ischemia was induced in rats by middle cerebral artery occlusion (MCAO) for 2 h followed by varying time points of reperfusion. The brain loci specific and time-dependent alterations were seen in the expression pattern of molecular markers, i.e., heat-shock protein 70 (HSP70) for cytoplasmic dysfunction, glucose-regulated protein 78 (GRP78), Caspase-12, C/EBP homologous protein/growth arrest and DNA damage-inducible gene 153 (CHOP/GADD153), activating transcription factor 4 (ATF-4), and Processed X-box protein 1 (xbp1) mRNA for ER dysfunction. Further, histological examinations indicated pronounced brain damage, massive neuronal loss, and DNA fragmentation predominantly in the striatum and cortex. The enhanced expression of GRP78, Caspase-12, CHOP/GADD153, ATF4 and processing of xbp1 mRNA in the affected brain regions clearly indicate the critical involvement of ER-mediated cell death/survival mechanisms and also collectively demonstrated the activation of unfolded protein response (UPR). Moreover, Salubrinal, a selective inhibitor of eIF2alpha dephosphorylation was used to counteract ER stress, which significantly increased the phosphorylation of eukaryotic translation initiation factor 2 subunit alpha (eIF2alpha), leading to reduced brain damage after I/R injury. Therefore, inhibition of ER stress following I/R injury may be used as key therapeutic target for neuroprotection.

Topics: Activating Transcription Factor 4; Animals; Brain; Caspase 12; Cinnamates; Disease Models, Animal; Disease Progression; DNA-Binding Proteins; Endoplasmic Reticulum; Functional Laterality; Gene Expression Regulation, Developmental; Heat-Shock Proteins; HSP72 Heat-Shock Proteins; In Situ Nick-End Labeling; Indoles; Infarction, Middle Cerebral Artery; Male; Phosphopyruvate Hydratase; Rats; Rats, Sprague-Dawley; Regulatory Factor X Transcription Factors; Reperfusion Injury; RNA, Messenger; Statistics, Nonparametric; Thiourea; Time Factors; Transcription Factor CHOP; Transcription Factors; X-Box Binding Protein 1

The mechanisms underlying disease manifestations in neurodegeneration remain unclear, but their understanding is critical to devising effective therapies. We carry out a longitudinal analysis in vivo of identified motoneurons selectively vulnerable (VUL) or resistant (RES) to motoneuron disease (amyotrophic lateral sclerosis, ALS) and show that subtype-selective endoplasmic reticulum (ER) stress responses influence disease manifestations. VUL motoneurons were selectively prone to ER stress and showed gradually upregulated ER stress markers from birth on in three mouse models of familial ALS (FALS). 25-30 days before the earliest denervations, ubiquitin signals increased in both VUL and RES motoneurons, but an unfolded protein response coupled with microglial activation was initiated selectively in VUL motoneurons. This transition was followed by selective axonal degeneration and spreading stress. The ER stress-protective agent salubrinal attenuated disease manifestations and delayed progression, whereas chronic enhancement of ER stress promoted disease. Thus, whereas all motoneurons are preferentially affected in ALS, ER stress responses in specific motoneuron subtypes influence the progressive manifestations of weakening and paralysis.

Topics: Amyotrophic Lateral Sclerosis; Animals; Biomarkers; Central Nervous System; Cinnamates; Disease Models, Animal; Disease Progression; Endoplasmic Reticulum; Genetic Predisposition to Disease; Gliosis; Mice; Mice, Neurologic Mutants; Microglia; Motor Neurons; Neuroprotective Agents; Oxidative Stress; Phenotype; Protein Folding; Thiourea; Ubiquitin; Ubiquitination; Wallerian Degeneration

Obstructive sleep apnea is associated with neural injury and dysfunction. Hypoxia/reoxygenation exposures, modeling sleep apnea, injure select populations of neurons, including hypoglossal motoneurons. The mechanisms underlying this motoneuron injury are not understood. We hypothesize that endoplasmic reticulum injury contributes to motoneuron demise. Hypoxia/reoxygenation exposures across 8 weeks in adult mice upregulated the unfolded protein response as evidenced by increased phosphorylation of PERK [PKR-like endoplasmic reticulum (ER) kinase] in facial and hypoglossal motoneurons and persistent upregulation of CCAAT/enhancer-binding protein-homologous protein (CHOP)/growth arrest and DNA damage-inducible protein (GADD153) with nuclear translocation. Long-term hypoxia/reoxygenation also resulted in cleavage and nuclear translocation of caspase-7 and caspase-3 in hypoglossal and facial motoneurons. In contrast, occulomotor and trigeminal motoneurons showed persistent phosphorylation of eIF-2a across hypoxia/reoxygenation, without activations of CHOP/GADD153 or either caspase. Ultrastructural analysis of rough ER in hypoglossal motoneurons revealed hypoxia/reoxygenation-induced luminal swelling and ribosomal detachment. Protection of eIF-2alpha phosphorylation with systemically administered salubrinal throughout hypoxia/reoxygenation exposure prevented CHOP/GADD153 activation in susceptible motoneurons. Collectively, this work provides evidence that long-term exposure to hypoxia/reoxygenation events, modeling sleep apnea, results in significant endoplasmic reticulum injury in select upper airway motoneurons. Augmentation of eIF-2a phosphorylation minimizes motoneuronal injury in this model. It is anticipated that obstructive sleep apnea results in endoplasmic reticulum injury involving motoneurons, whereas a critical balance of phosphorylated eIF-2a should minimize motoneuronal injury in obstructive sleep apnea.

Topics: Animals; Brain Stem; Caspases; Choline O-Acetyltransferase; Cinnamates; Disease Models, Animal; eIF-2 Kinase; Endoplasmic Reticulum; Eukaryotic Initiation Factor-2; Gene Expression Regulation; Hypoxia; Male; Mice; Mice, Inbred C57BL; Microscopy, Electron, Transmission; Motor Neurons; Oxidative Stress; Phosphorylation; Sleep Apnea Syndromes; Thiourea; Transcription Factor CHOP