The alternative initiation factor eIF2A plays key role in RAN translation of myotonic dystrophy type 2 CCUG•CAGG repeats.

Repeat-associated non-ATG (RAN) proteins have been reported in 11 microsatellite expansion disorders but the factors that allow RAN translation to occur and the effects of different repeat motifs and alternative AUG-like initiation codons are unclear. We studied the mechanisms of RAN translation across myotonic dystrophy type 2 (DM2) expansion transcripts with (CCUG) or without (CAGG) efficient alternative AUG-like codons. To better understand how DM2 LPAC and QAGR RAN proteins are expressed, we generated a series of CRISPR/Cas9-edited HEK293T cell lines. We show that LPAC and QAGR RAN protein levels are reduced in protein kinase R (PKR)-/- and PKR-like endoplasmic reticulum kinase (PERK)-/- cells, with more substantial reductions of CAGG-encoded QAGR in PKR-/- cells. Experiments using mutant eIF2α-S51A HEK293T cells show that p-eIF2α is required for QAGR production. In contrast, LPAC levels were only partially reduced in these cells, suggesting that both non-AUG and close-cognate initiation occur across CCUG RNAs. Overexpression of the alternative initiation factor eIF2A increases LPAC and QAGR protein levels but, notably, has a much larger effect on QAGR expressed from CAGG-expansion RNAs that lack efficient close-cognate codons. The effects of eIF2A on increasing LPAC are consistent with previous reports that eIF2A affects CUG-initiation translation. The observation that eIF2A also increases QAGR proteins is novel because CAGG expansion transcripts do not contain CUG or similarly efficient close-cognate AUG-like codons. For QAGR but not LPAC, the eIF2A-dependent increases are not seen when p-eIF2α is blocked. These data highlight the differential regulation of DM2 RAN proteins and eIF2A as a potential therapeutic target for DM2 and other RAN diseases.

Dietary supplementation with tBHQ, an Nrf2 stabilizer molecule, confers neuroprotection against apoptosis in amyloid ß-injected rat.

Nuclear factor erythroid 2-related factor 2 (Nrf2) coordinates the up-regulation of cytoprotective genes via the antioxidant response element (ARE). There is significant evidence that oxidative stress is a critical event in the pathogenesis of AD. Considering the protective role of Nrf2 against oxidative injury, we studied to determine whether in vivo toxicity of amyloid ß (Aß) can be attenuated by tBHQ, an Nrf2 stabilizer, Using an Aß injection model. We demonstrated that pre-activation of endogenous Nrf2 by tBHQ attenuated Aß-induced caspase-3 expression. tBHQ enhanced GSH, decreased MDA level, and inhibited NF-κB. This investigation provides the first documentation of tBHQ's neuroprotective effect through decrease of Aß accumulation in rat brain. Our results show the involvement of Hsp-70 in this protective effect. In summary tBHQ treatment for 1 week prior to Aß injection protected against the oxidative damage, apoptosis and Aß accumulation in rats.

Stabilization of Nrf2 by tBHQ prevents LPS-induced apoptosis in differentiated PC12 cells.

The inflammatory reaction plays an important role in the pathogenesis of the neurodegenerative disorders. tert-butylhydroquinone (tBHQ) exhibits a wide range of pharmacological activities including anti-oxidative and anti-inflammatory action. In this study, we tried to elucidate possible effects of tBHQ on lipopolysaccharide (LPS)-induced inflammatory reaction and its underlying mechanism in neuron-like PC12 cells. tBHQ inhibited LPS-induced generation of reactive oxygen species (ROS) and elevation of intracellular calcium level. It also inhibited LPS-induced cyclooxygenase 2 (COX-2), TNF-α, nuclear factor KappaB (NF-kB), and caspase-3 expression in a dose-dependent manner while stabilizing nuclear factor-erythroid 2 p45-related factor 2. Moreover, the phosphorylations of p38, ERK1/2, and JNK were suppressed by tBHQ. These results suggest that the anti-inflammatory properties of tBHQ might result from inhibition of COX-2 and TNF-α expression, inhibition of NF-kB nuclear translocation along with suppression of MAP kinases (p38, ERK1/2, and JNK) phosphorylation in PC12 cells, so may be a useful agent for prevention of inflammatory diseases.

Attenuation of NF-kappaB and activation of Nrf2 signaling by 1,2,4-triazine derivatives, protects neuron-like PC12 cells against apoptosis.

Oxidative stress has been implicated in the etiology of neurodegenerative diseases and aging. Indeed, accumulation of reactive oxygen species, such as hydrogen peroxide, generated by inflammatory cells, leads to oxidative stress, which may contribute to the neuronal degeneration observed in a wide variety of neurodegenerative disorders of the central nervous system, such as Alzheimer's disease. The present study indicates that H(2)O(2)-induced cell death can be inhibited in the presence of 1,2,4-triazine derivatives, as measured by MTT and caspase-3 activity. We further show that these compounds exert their protective effect by up-regulation of hemeoxygenase-1, glutamylcysteine synthetase, glutathione peroxidase and nuclear factor-erythroid 2 p45-related factor 2 (Nrf2), while they inhibit NF-kappaB and decrease lipid peroxidation. It shows that there is a potential cross talk between NF-kappaB and Nrf2, an important cytoprotective transcription factor in the presence of these compounds. Moreover, in order for drugs to be effective in the treatment of neurodegenerative diseases, they must be capable of penetrating the blood-brain barrier, whereas more than 98% of all potential central nervous system drugs don't cross. Using a reliable model based on the artificial neural network indicated that these compounds satisfy this requirement.

Synthesis and in vitro evaluation of novel 1,2,4-triazine derivatives as neuroprotective agents.

The role of novel triazine derivatives against oxidative stress exerted by hydrogen peroxide on differentiated rat pheochromocytoma (PC12) cell line was examined and a consistent protection from H(2)O(2)-induced cell death, associated with a marked reduction in caspase-3 activation, was observed. Moreover, activation of NF-kappaB, a known regulator of a host of genes that involves in specific stress and inflammatory responses by H(2)O(2), was greatly impaired by triazine pretreatment in differentiated PC12 cells. Neuroprotective effect of such compounds may represent a promising approach for treatment of neurodegenerative diseases.

Antibody Therapy Targeting RAN Proteins Rescues C9 ALS/FTD Phenotypes in C9orf72 Mouse Model.

The intronic C9orf72 G4C2 expansion, the most common genetic cause of ALS and FTD, produces sense- and antisense-expansion RNAs and six dipeptide repeat-associated, non-ATG (RAN) proteins, but their roles in disease are unclear. We generated high-affinity human antibodies targeting GA or GP RAN proteins. These antibodies cross the blood-brain barrier and co-localize with intracellular RAN aggregates in C9-ALS/FTD BAC mice. In cells, α-GA1 interacts with TRIM21, and α-GA1 treatment reduced GA levels, increased GA turnover, and decreased RAN toxicity and co-aggregation of proteasome and autophagy proteins to GA aggregates. In C9-BAC mice, α-GA1 reduced GA as well as GP and GR proteins, improved behavioral deficits, decreased neuroinflammation and neurodegeneration, and increased survival. Glycosylation of the Fc region of α-GA1 is important for cell entry and efficacy. These data demonstrate that RAN proteins drive C9-ALS/FTD in C9-BAC transgenic mice and establish a novel therapeutic approach for C9orf72 ALS/FTD and other RAN-protein diseases.

RAN Translation in Huntington Disease.

Huntington disease (HD) is caused by a CAG ⋅ CTG expansion in the huntingtin (HTT) gene. While most research has focused on the HTT polyGln-expansion protein, we demonstrate that four additional, novel, homopolymeric expansion proteins (polyAla, polySer, polyLeu, and polyCys) accumulate in HD human brains. These sense and antisense repeat-associated non-ATG (RAN) translation proteins accumulate most abundantly in brain regions with neuronal loss, microglial activation and apoptosis, including caudate/putamen, white matter, and, in juvenile-onset cases, also the cerebellum. RAN protein accumulation and aggregation are length dependent, and individual RAN proteins are toxic to neural cells independent of RNA effects. These data suggest RAN proteins contribute to HD and that therapeutic strategies targeting both sense and antisense genes may be required for efficacy in HD patients. This is the first demonstration that RAN proteins are expressed across an expansion located in an open reading frame and suggests RAN translation may also contribute to other polyglutamine diseases.

Salvia macilenta exhibits antiglycating activity and protects PC12 cells against H2O 2-induced apoptosis.

Salvia macilenta is a member of the genus Salvia (Laminaceae) whose antioxidant activity and neuroprotective effect has been shown previously. The present study aimed to examine the antiglycating and antiapoptotic abilities of methanolic extract of this plant. Moreover, the effect of S. macilenta on neurite outgrowth and complexity after exposure to H2O2 has been studied. Base on our results, S. macilenta has antiglycating activity and protects PC12 cells against oxidative stress-induced apoptotic cell death, as examined by Hoechst staining and Western blot analysis of caspase-3, Bax, Bcl-2 and PARP. We further showed that S. macilenta decreased neurite growth and complexity impairment in differentiated PC12 cells exposed to oxidative stress. It caused a decrease in cell body area, neurite width, and the proportion of bipolar cells, while significantly increasing neurite length, the number of primary neurites per cell and the ratio of nodes to primary neuritis. All around, the mentioned results open a new horizon for future works to use this plant as a potential neuroprotective agent.

Involvement of molecular chaperones and the transcription factor Nrf2 in neuroprotection mediated by para-substituted-4,5-diaryl-3-thiomethyl-1,2,4-triazines.

Much evidence supports that oxidative stress plays an important role in the pathogenesis of neurodegenerative diseases, such as Alzheimer's disease. Herein, we studied the compensatory/adaptive mechanisms involved in 3-thiomethyl-5,6-(diphenyl)-1,2,4-triazine and 3-thiomethyl-5,6-(dichlorophenyl)-1,2,4-triazine neuroprotection. We found that these compounds could counteract H(2)O(2)-induced rupture of neurite outgrowth in differentiated PC12 cells. In addition, we found that pretreatment of cells with triazine derivatives could modulate the expression of heat shock proteins Hsp70, Hsp90, and Hsp32 in H(2)O(2)-treated PC12 cells. These compounds could also increase nuclear level of stress sensing transcription factor, NF-E2 related factor 2, which contributes to redox homeostasis and cell survival following stress. As a result, the elevated levels of glutamylcysteine synthetase, glutathione peroxidase-1, and glutathione, as well as superoxide dismutase and catalase, increased cellular antioxidant capacity. Studying the relation between structure and activity of these compounds will pave the way for exploiting preventive and/or therapeutic strategies for the management of oxidative stress-mediated disorders.

S. choloroleuca, S. mirzayanii and S. santolinifolia protect PC12 cells from H(2)O (2)-induced apoptosis by blocking the intrinsic pathway.

Several studies have shown that neuronal cell death due to apoptosis is the major reason for cognitive decline in Alzheimer's disease. In this study, we report the anti-apoptotic effects of three Salvia species from Iran-S. choloroleuca, S. mirzayanii and S. santolinifolia-against H(2)O(2)-induced cytotoxicity in neuron-like PC12 cells. We showed that these antioxidant species could interfere with the intrinsic pathway of apoptosis by attenuating Bax/Bcl-2 ratio, decreasing outer mitochondrial membrane break and decreasing cytochrome c release to cytoplasm. Interestingly, we found that these species were able to replenish reduced glutathione level which affects cellular redox status and cytochrome c activity. Moreover, the decreased level of caspase-3, the executioner caspase, resulted in decrease of PARP-1 cleavage. Anti-apoptotic effects of these species along with their antioxidant effects, may represent a promising approach for treatment of neurodegenerative diseases.

3-Thiomethyl-5,6-(dimethoxyphenyl)-1,2,4-triazine improves neurite outgrowth and modulates MAPK phosphorylation and HSPs expression in H2O2-exposed PC12 cells.

Neurite outgrowth is an important aspect of neuronal plasticity and regeneration after neuronal injury. In this study we aimed to investigate the possible effect of 3-thiomethyl-5,6-dimethoxyphenyl-1,2,4-triazine (TDMT) on H(2)O(2)-induced impairment of neurite outgrowth. We found that TDMT could improve neurite outgrowth and neurite complexity in H(2)O(2)-exposed PC12 cells. Moreover, we found elevated levels of Hsp-70 and suppressed level of Hsp-90 in TDMT-treated cells in the presence of H(2)O(2). As another important signaling pathways that play role in neuritogenesis, as well as apoptosis, we measured the level of phosphorylated and total MAPKs proteins, JNK, ERK and p38 MAPK. We found that TDMT inhibits oxidative stress-induced phosphorylation of MAPKs. Since HSPs and MAPKs are both involved in coping with environmental changes, it will not be surprising if they can modify or augment each other's activity. Neuroprotective effect of this compound could represent a promising approach for treatment of neurodegenerative diseases.

Alginate oligosaccharide protects against endoplasmic reticulum- and mitochondrial-mediated apoptotic cell death and oxidative stress.

Oxidative stress is a major component of harmful cascades activated in neurodegenerative disorders. We sought to elucidate possible effects of alginate oligosaccharide (AOS) on H(2)O(2)-induced cell death and to determine the underlying molecular mechanisms in neuron-like PC12 cells. We found that AOS treatment protected PC12 cells against H(2)O(2)-induced endoplasmic reticulum (ER) and mitochondrial-dependent apoptotic cell death. AOS promoted Bcl-2 expression, while blocked Bax expression and inhibited H(2)O(2)-induced caspase-3 activation. It also blocked PARP cleavage. AOS acted on key molecules in apoptotic cell death pathway and reduced p53, p38, c-June NH2-terminal kinase phosphorylations, inhibited NFkB, and enhanced Nrf2 activation. These results suggest that treatment of PC12 cells with AOS can block H(2)O(2)-induced oxidative stress and caspase-dependent apoptotic cascades originating from both ER and mitochondria. Our in vivo experiments further confirm the neuroprotective potential of AOS against Aß-induced neural damage. According to our data, the involvement of caspase-independent pathway in AOS-induced protection appears to be unlikely.

Antioxidant and antiglycating activities of Salvia sahendica and its protective effect against oxidative stress in neuron-like PC12 cells.

Increased oxidative stress is widely accepted to be a factor in the development and progression of Alzheimer's disease (AD). Here we introduced Salvia sahendica as a protective agent in differentiated PC12 cells, which are commonly considered to be a reliable model of neuronal cells. Our results demonstrated that S. sahendica has antioxidant and antiglycating properties in in vitro system and these properties are expanded into H(2)O(2)-induced model. S. sahendica inhibited H(2)O(2)-induced cell death in PC12 cells. We further showed that this plant exerts its protective effect by increasing superoxide dismutase and catalase levels, reducing lipid peroxidation and upregulating hemoxygenase-1 and glutamylcysteine synthetase proteins. This study raises the possibility of developing S. sahendica as a potential neuroprotective agent.

Chemical composition analysis, antioxidant, antiglycating activities and neuroprotective effects of S. choloroleuca, S. mirzayanii and S. santolinifolia from Iran.

This study was designed to examine antioxidant activities, antiglycating abilities and neuroprotective effects of methanolic extracts of Salvia choloroleuca, Salvia santolinifolia and Salvia mirzayanii from Iran. The extracts were screened for their possible antioxidant activities by several biochemical assays such as DPPH, FRAP, ß-carotene bleaching and TEAC assays. HPLC analysis of these extracts led to the separation of a number of components such as catechine and rosmarinic acid. Based on our results, all these plants had antioxidant and antiglycating activities, among them S. choloroleuca seems to be the most effective one. Furthermore, these species not only showed no cytotoxic effects in neuron-like PC12 cells, but also protected them against oxidative stress-induced cell death, exerted by H(2)O(2). We further showed that these plants increase superoxide dismutase and catalase levels, reduce lipid peroxidation and up regulate hemeoxygenase-1 and glutamylcysteine synthetase proteins. This study raised the possibility of developing these plants as potential neuroprotective agents.

Designing a highly efficient chemical chaperone system using chitosan-coated alginate.

In the present work we prepared chitosan-coated alginate beads, to use as a chemical chaperone based on the electrostatic interaction between the carboxylate groups of alginate and the ammonium groups of chitosan. This procedure was an attempt for designing a highly efficient chemical chaperone to improve protein stability and refolding. Based on enzyme recovered activity, turbidity, far-UV CD and fluorescence data, alkaline phosphatase can be stabilized and refolded to a higher degree in the presence of alginate capsules compared with unassisted form and was further improved by including chitosan. Finally the maximum yield was obtained when the refolding process was achieved under a well worked out temperature program: incubation of the captured-enzyme for 20 min at 4 degrees C followed by overnight incubation at 22 degrees C, which showed that aggregation is a major limitation to refolding.