C-terminal mechano-growth factor induces heme oxygenase-1-mediated neuroprotection of SH-SY5Y cells via the protein kinase Cϵ/Nrf2 pathway

Effects of choline supplementation on growth performance, liver histology, nonspecific immunity and related genes expression of hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ E. lanceolatu) fed with high-lipid diets

This study was conducted to evaluate the effect of dietary choline levels on growth performance, liver histology, nonspecific immunity and related gene expression of hybrid grouper (♀ Epinephelus fuscoguttatus × ♂ E. lanceolatus) fed with high-lipid diets. The fish (initial body weight 6.86 ± 0.01 g) were fed diets containing different choline levels (0, 5, 10, 15, and 20 g/kg, named D1, D2, D3, D4, and D5, respectively) for 8 weeks. The results showed that:(1) dietary choline levels had no significant effect on final body weight (FBW), feed conversion rate (FCR), visceral somatic index(VSI) and condition factor (CF) compared with the control group (P > 0.05). However, the hepato somatic index (HSI) in the D2 group was significantly lower than that in the control group and the survival rate (SR) in the D5 group was significantly lower (P < 0.05). (2) with dietary choline level increasing, alkaline phosphatase (AKP) and superoxide dismutase (SOD) of serum showed a tendency to increase and then decrease, and the maximum values were obtained in the D3 group, but the contents of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) decreased significantly (P < 0.05). (3) Immunoglobulin M (IgM), lysozyme (LYZ), catalase (CAT), total antioxidative capacity (T-AOC), and SOD in the liver all showed a trend of first increase and then decrease with the dietary choline level increased, and all of them achieved the maximum value at D4 group (P < 0.05), while reactive oxygen species (ROS) and malondialdehyde (MDA) in the liver decreased significantly (P < 0.05). (4) results from liver sections suggest that appropriate levels of choline can improve cell structure, compared with the control group, the damaged histological morphology of the liver was relieved and even returned to normal in D3 group. (5) in the D3 group, choline significantly upregulated the expression of hepatic sod and cat mRNA, whereas the expression of cat in the D5 group was significantly lower than that in the control group (P < 0.05); And the supply of choline stimulated a significant down-regulation of interleukin 6 (il6), myeloid differentiation factor 8 (myd88), toll-like receptor 22 (tlr22) mRNA expression levels in liver, while the expression of cellular tumor antigen p53 (p53) and interleukin 10 (il10) showed an upward and then downward trend (P < 0.05). In general, choline can improve the immunity of hybrid grouper by regulating non-specific immune-related enzyme activity and gene expression and reducing oxidative stress induced by high-lipid diet.

In vitro neurotoxic potential of emerging flame retardants on neuroblastoma cells in an acute exposure scenario

Since 2004, some legacy flame retardants (FRs) were restricted or removed from the European markets due to their concern on human health. Both organophosphorus FRs (OPFRs) and novel brominated FRs (NBFRs) have replaced them because they are presumably safer and less persistent emerging FRs (EFRs) and their exposure is currently occurring in indoor environments at high levels. Little is known about the neurotoxic potential risk of these EFRs in humans. The present study was aimed at assessing the acute neurotoxicity potential of Tris(1, 3-dichloro-2-propyl)phosphate (TDCPP), triphenyl phosphate (TPhP), Bis(2-ethylhexyl)tetrabromophthalate (BEH-TEBP) and 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EH-TBB) on human neuroblastoma cells (SH-SY5Y). SH-SY5Y were exposed to these EFRs at low concentrations -ranging 2.5-20 μM. during 2-24 h. We investigated viability, mitochondrial function, oxidative stress, inflammatory response, as well as neural plasticity and development. The results have demonstrated that selected EFRs (TDCPP, TPhP, EH-TBB and BEH-TBP) did not impair neural function on SH-SY5Y as acute response. To the best of our knowledge, this has been the first study focused on evaluating the neural affection of TPhP on SH-SY5Y cells and of EH-TBB and BEH-TBP on neural cells. We also assessed for the first time almost all endpoints after FR exposure on neural cell lines.

Mechano-growth factor E-domain modulates cardiac contractile function through 14-3-3 protein interactomes

In the heart, alternative splicing of the igf-I gene produces two isoforms: IGF-IEa and IGF-IEc, (Mechano-growth factor, MGF). The sequence divergence between their E-domain regions suggests differential isoform function. To define the biological actions of MGF's E-domain, we performed in silico analysis of the unique C-terminal sequence and identified a phosphorylation consensus site residing within a putative 14-3-3 binding motif. To test the functional significance of Ser 18 phosphorylation, phospho-mimetic (S/E18) and phospho-null (S/A18) peptides were delivered to mice at different doses for 2 weeks. Cardiovascular function was measured using echocardiography and a pressure-volume catheter. At the lowest (2.25 mg/kg/day) and highest (9 mg/kg/day) doses, the peptides produced a depression in systolic and diastolic parameters. However, at 4.5 mg/kg/day the peptides produced opposing effects on cardiac function. Fractional shortening analysis also showed a similar trend, but with no significant change in cardiac geometry. Microarray analysis discovered 21 genes (FDR p < 0.01), that were expressed accordant with the opposing effects on contractile function at 4.5 mg/kg/day, with the nuclear receptor subfamily 4 group A member 2 (Nr4a2) identified as a potential target of peptide regulation. Testing the regulation of the Nr4a family, showed the E-domain peptides modulate Nr4a gene expression following membrane depolarization with KCl in vitro. To determine the potential role of 14-3-3 proteins, we examined 14-3-3 isoform expression and distribution. 14-3-3γ localized to the myofilaments in neonatal cardiac myocytes, the cardiac myocytes and myofilament extracts from the adult heart. Thermal shift analysis of recombinant 14-3-3γ protein showed the S/A18 peptide destabilized 14-3-3γ folding. Also, the S/A18 peptide significantly inhibited 14-3-3γ's ability to interact with myosin binding protein C (MYPC3) and phospholamban (PLN) in heart lysates from dobutamine injected mice. Conversely, the S/E18 peptide showed no effect on 14-3-3γ stability, did not inhibit 14-3-3γ's interaction with PLN but did inhibit the interaction with MYPC3. Replacing the glutamic acid with a phosphate group on Ser 18 (pSer18), significantly increased 14-3-3γ protein stability. We conclude that the state of Ser 18 phosphorylation within the 14-3-3 binding motif of MGF's E-domain, modulates protein-protein interactions within the 14-3-3γ interactome, which includes proteins involved in the regulation of contractile function.

Pharmacological Modulation of Nrf2/HO-1 Signaling Pathway as a Therapeutic Target of Parkinson's Disease

Parkinson's disease (PD) is a complex neurodegenerative disorder featuring both motor and nonmotor symptoms associated with a progressive loss of dopaminergic neurons in the substantia nigra pars compacta. Oxidative stress (OS) has been implicated in the pathogenesis of PD. Genetic and environmental factors can produce OS, which has been implicated as a core contributor to the initiation and progression of PD through the degeneration of dopaminergic neurons. The transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) orchestrates activation of multiple protective genes, including heme oxygenase-1 (HO-1), which protects cells from OS. Nrf2 has also been shown to exert anti-inflammatory effects and modulate both mitochondrial function and biogenesis. Recently, a series of studies have reported that different bioactive compounds were shown to be able to activate Nrf2/antioxidant response element (ARE) and can ameliorate PD-associated neurotoxin, both in animal models and in tissue culture. In this review, we briefly overview the sources of OS and the association between OS and the pathogenesis of PD. Then, we provided a concise overview of Nrf2/ARE pathway and delineated the role played by activation of Nrf2/HO-1 in PD. At last, we expand our discussion to the neuroprotective effects of pharmacological modulation of Nrf2/HO-1 by bioactive compounds and the potential application of Nrf2 activators for the treatment of PD. This review suggests that pharmacological modulation of Nrf2/HO-1 signaling pathway by bioactive compounds is a therapeutic target of PD.

Metformin attenuates rotenone-induced oxidative stress and mitochondrial damage via the AKT/Nrf2 pathway

Oxidative stress and mitochondrial dysfunction are now widely accepted as the major factors involved in the pathogenesis of Parkinson's disease (PD). Rotenone, a commonly used environmental toxin also reproduces these principle pathological features of PD. Hence, it is used frequently to induce experimental PD in cells and animals. In this study, we evaluated the neuroprotective effects of metformin against rotenone-induced toxicity in SH-SY5Y cells. Metformin treatment clearly rescued these cells from rotenone-mediated cell death via the reduction of the cytosolic and mitochondrial levels of reactive oxygen species and restoration of mitochondrial function. Furthermore, metformin upregulated PGC-1α, the master regulator of mitochondrial biogenesis and key antioxidant molecules, including glutathione and superoxide dismutase. We demonstrated that the drug exerted its cytoprotective effects by activating nuclear factor erythroid 2-related factor 2 (Nrf2)/heme-oxygenase (HO)-1 pathway, which in turn, is dependent on AKT activation by metformin. Thus, our results implicate that metformin provides neuroprotection against rotenone by inhibiting oxidative stress in the cells by inducing antioxidant system via upregulation of transcription mediated by Nrf2, thereby restoring the rotenone-induced mitochondrial dysfunction and energy deficit in the cells.

Role of Alternatively Spliced Messenger RNA (mRNA) Isoforms of the Insulin-Like Growth Factor 1 (IGF1) in Selected Human Tumors

Insulin-like growth factor 1 (IGF1) is a key regulator of tissue growth and development that is also implicated in the initiation and progression of various cancers. The human IGF1 gene contains six exons and five long introns, the transcription of which is controlled by two promoters (P1 and P2). Alternate promoter usage, as well as alternative splicing (AS) of IGF1, results in the expression of six various variants (isoforms) of mRNA, i.e., IA, IB, IC, IIA, IIB, and IIC. A mature 70-kDa IGF1 protein is coded only by exons 3 and 4, while exons 5 and 6 are alternatively spliced code for the three C-terminal E peptides: Ea (exon 6), Eb (exon 5), and Ec (fragments of exons 5 and 6). The most abundant of those transcripts is IGF1Ea, followed by IGF1Eb and IGF1Ec (also known as mechano-growth factor, MGF). The presence of different IGF1 transcripts suggests tissue-specific auto- and/or paracrine action, as well as separate regulation of both of these gene promoters. In physiology, the role of different IGF1 mRNA isoforms and pro-peptides is best recognized in skeletal muscle tissue. Their functions include the development and regeneration of muscles, as well as maintenance of proper muscle mass. In turn, in nervous tissue, a neuroprotective function of short peptides, produced as a result of IGF1 expression and characterized by significant blood-brain barrier penetrance, has been described and could be a potential therapeutic target. When it comes to the regulation of carcinogenesis, the potential biological role of different var iants of IGF1 mRNAs and pro-peptides is also intensively studied. This review highlights the role of IGF1 isoform expression (mRNAs, proteins) in physiology and different types of human tumors (e.g., breast cancer, cervical cancer, colorectal cancer, osteosarcoma, prostate and thyroid cancers), as well as mechanisms of IGF1 spliced variants involvement in tumor biology.

L-carnitine regulated Nrf2/Keap1 activation in vitro and in vivo and protected oxidized fish oil-induced inflammation response by inhibiting the NF-κB signaling pathway in Rhynchocypris lagowski Dybowski

Nrf2/Keap1 pathway is associated with oxidative stress. l-carnitine is currently under preclinical evaluation as a antioxidant, but the use of l-carnitine in aquaculture has been poorly evaluated and so far no mechanism has been demonstrated. Here, we explored the effects of l-carnitine in vitro and in vivo and discussed the possible molecular mechanisms involved. Firstly, Nrf2-siRNA significantly knocked down the mRNA level of Nrf2 in FHM cells. Thus, the activities of antioxidant enzymes (T-SOD, CAT, GSH-PX) and the level of antioxidant substance (GSH) and the level of MDA showed that Nrf2-siRNA pretreatment weakened the protective effect of l-carnitine. Moreover, the mRNA levels of Keap1, Nrf2, Maf and HO-1 indicated that l-carnitine regulated Nrf2/Keap1 activation. Furthermore, oxidized fish oil remarkably suppressed growth in Rhynchocypris lagowski Dybowski, and the lower antioxidant capacity was also observed in liver. According to the results of immune related indexes (the levels of IL-1β, TNF-α, LZM, AKP) in serum and the mRNA levels of immune related genes (NF-κB, IL-1β, TNF-α, IL-8, IL-10 and TGF-β) in liver, oxidized fish oil also induced inflammatory response in fish. Also, l-carnitine supplementation can relieve this bad condition. In conclusion, l-carnitine regulated Nrf2/Keap1 activation in vitro and in vivo and protected oxidized fish oil-induced inflammation response by inhibiting the NF-κB signaling pathway in Rhynchocypris lagowski Dybowski.

Nrf2 Mediates the Anti-apoptotic and Anti-inflammatory Effects Induced by Gastrodin in Hydrogen Peroxide-Treated SH-SY5Y Cells

Redox impairment, inflammation, and increased rates of cell death are central players during neurodegeneration. In that context, activation of the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) has been viewed as an interesting strategy in order to reduce the impact of redox dysfunction and neuroinflammation on cell fate. There is evidence indicating that the benefits caused by natural products in the brain may be due to the ability of these agents in upregulating Nrf2. Gastrodin (GAS) induces anti-oxidant, anti-inflammatory, and anti-apoptotic actions in brain cells. Nonetheless, the mechanisms underlying such effects are not clear yet. Therefore, we investigated here whether GAS would affect apoptosis and inflammation in the human neuroblastoma cell line (SH-SY5Y) exposed to hydrogen peroxide (H₂O₂). GAS at 1-25 μM was administrated to the cells during 30 min before a challenge with H₂O₂ at 300 μM for additional 24 h. GAS prevented the activation of the intrinsic apoptotic pathway by modulating the levels of Bcl-2 and Bax, causing a decrease in the release of cytochrome c to the cytosol. GAS also prevented the activation of the pro-apoptotic enzymes caspase-9 and caspase-3. Consequently, GAS abrogated poly (ADP-ribose) polymerase (PARP) cleavage and DNA fragmentation in the H₂O₂-treated SH-SY5Y cells. Moreover, GAS reduced the levels of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) and the activity of nuclear factor-κB in H₂O₂-treated cells. Silencing of Nrf2 by small interfering RNA (siRNA) suppressed the GAS-induced cytoprotection. Thus, GAS elicited anti-apoptotic and anti-inflammatory effects by a mechanism involving Nrf2 in SH-SY5Y cells.

Carnosic Acid Pretreatment Attenuates Mitochondrial Dysfunction in SH-SY5Y Cells in an Experimental Model of Glutamate-Induced Excitotoxicity

Mitochondria are the major site of adenosine triphosphate (ATP) production in mammalian cells. Moreover, mitochondria produce most of the reactive oxygen species (ROS) in nucleated cells. Redox and bioenergetic abnormalities have been seen in mitochondria during the onset and progression of neurodegenerative diseases. In that context, excitotoxicity induced by glutamate (GLU) plays an important role in mediating neurotoxicity. Several drugs have been used in the treatment of diseases involving excitotoxicity. Nonetheless, some patients (20-30%) present drug resistance. Thus, it is necessary to find chemicals able to attenuate mitochondrial dysfunction in the case of excitotoxicity. In this work, we treated the human neuroblastoma SH-SY5Y cell line with the diterpene carnosic acid (CA) at 1 μM for 12 h prior to the exposure to GLU for further 24 h. We found that CA prevented the GLU-induced mitochondrion-related redox impairment and bioenergetic decline in SH-SY5Y cells. CA also downregulated the pro-apoptotic stimulus elicited by GLU in this experimental model. CA exerted mitochondrial protection by a mechanism associated with the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2), since silencing of this protein with small interfering RNA (siRNA) suppressed the CA-induced protective effects. Future directions include investigating whether CA would be able to modulate mitochondrial function and/or dynamics in in vivo experimental models of excitotoxicity.

PMA-triggered PKCε activity enhances Nrf2-mediated antiviral response on fish rhabdovirus infection

Viral infection is often accompanied with alteration of intracellular redox state, especially an imbalance between reactive oxygen species (ROS) production and antioxidant cellular defenses. The previous studies showed that an antioxidant cellular defense system, the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2), played an important role against spring viraemia of carp virus (SVCV) infection in fish. To further reveal the mediated mechanism that Nrf2 active state was affected by protein kinase C (PKC), here we evaluated SVCV replication in host cells by treated with a strong activator of PKC phorbol-12-myristate-13-acetate (PMA) and an inhibitor staurosporine. Our results showed that PMA significantly repressed SVCV replication and viral-induced apoptosis in Epithelioma papulosum cyprini (EPC) cell, suggesting that PKC may exhibit an anti-SVCV effect. Likewise, PMA resulted in a higher phosphorylation levels of PKCε rather than PKCα/β to participate in the activation of Nrf2, mainly involved in the activation of Nrf2 phosphorylation of Ser40 to favor Nrf2 translocation to nucleus. Furthermore, the data revealed that PMA up-regulated an antiviral response heme oxygenase-1 (HO1) gene expression that was confirmed as the key player against SVCV infection by HO1 specific siRNA. Overall, this study provided a new therapeutic target for the treatment of SVCV infection, and modulating PKC activity could be used for the prevention and treatment of SVCV.

Inhibition of the Nrf2/HO-1 Axis Suppresses the Mitochondria-Related Protection Promoted by Gastrodin in Human Neuroblastoma Cells Exposed to Paraquat

Mitochondria are double-membrane organelles involved in the transduction of energy from different metabolic substrates into adenosine triphosphate (ATP) in mammalian cells. The oxidative phosphorylation system is comprised by the activity of the respiratory chain and the complex V (ATP synthase/ATPase). This system is dependent on oxygen gas (O₂) in order to maintain a flux of electrons in the respiratory chain, since O₂ is the final acceptor of these electrons. Electron leakage from this complex system leads to the continuous generation of reactive species in the cells. The mammalian cells exhibit certain mechanisms to attenuate the consequences originated from the constant exposure to these reactive species. In this context, the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) and one of the enzymes whose expression is modulated by Nrf2, heme oxygenase-1 (HO-1), take a central role in inducing cytoprotection in humans. Mitochondrial abnormalities are observed during intoxication and in certain diseases, including neurodegeneration. Mitochondrial protection promoted by natural compounds has attracted the attention of researchers due to the promising effects these agents induce experimentally. In this regard, we examined here whether and how gastrodin (GAS), a phenolic glucoside, would prevent the paraquat (PQ)-induced mitochondrial impairment in the SH-SY5Y cells. The cells were exposed to GAS (25 μM) for 4 h prior to the challenge with PQ at 100 μM for additional 24 h. The silencing of Nrf2 by siRNA or the inhibition of HO-1 by ZnPP IX suppressed the GAS-elicited cytoprotection. Therefore, GAS promoted mitochondrial protection by an Nrf2/HO-1-dependent manner.

Evaluation of the Mitochondria-Related Redox and Bioenergetics Effects of Gastrodin in SH-SY5Y Cells Exposed to Hydrogen Peroxide

Mitochondrion is the main site of ATP production in animal cells and also orchestrates signaling pathways associated with cell survival and death. Mitochondrial dysfunction has been linked to bioenergetics and redox impairment in human diseases, such as neurodegeneration and cardiovascular disease. Protective agents able to attenuate mitochondrial impairment are of pharmacological interest. Gastrodin (GAS; 4-hydroxybenzyl alcohol 4-O-beta-D-glucoside) is a phenolic glucoside obtained from the Chinese herbal medicine Gastrodia elata Blume and exhibits antioxidant, anti-inflammatory, and antiapoptotic effects in several cell types. GAS is able to cross the blood-brain barrier, reducing the impact of different stressors on the cognition of experimental animals. In the present work, we investigated whether GAS would protect mitochondria of human SH-SY5Y neuroblastoma cells against an exposure to a pro-oxidant agent. The cells were treated with GAS at 25 μM for 30 min before the administration of hydrogen peroxide (H₂O₂) at 300 μM for an additional 3 or 24 h, depending on the assay. We evaluated both mitochondrial redox state and function parameters and analyzed the mechanism by which GAS protected mitochondria in this experimental model. Silencing of the nuclear factor erythroid 2-related factor 2 (Nrf2) transcription factor suppressed the GAS-induced mitochondrial protection seen here. Moreover, Nrf2 knockdown abrogated the effects of GAS on cell viability, indicating a potential role for Nrf2 in both mitochondrial and cellular protection promoted by GAS. Further research would be necessary to investigate whether GAS would be able to induce similar effects in in vivo experimental models.

Amperometric Microsensors Monitoring Glutamate-Evoked In Situ Responses of Nitric Oxide and Carbon Monoxide from Live Human Neuroblastoma Cells

In the brain, nitric oxide (NO) and carbon monoxide (CO) are important signaling gases which have multifaceted roles, such as neurotransmitters, neuromodulators, and vasodilators. Even though it is difficult to measure NO and CO in a living system due to their high diffusibility and extremely low release levels, electrochemical sensors are promising tools to measure in vivo and in vitro NO and CO gases. In this paper, using amperometric dual and septuple NO/CO microsensors, real-time NO and CO changes evoked by glutamate were monitored simultaneously for human neuroblastoma (SH-SY5Y) cells. In cultures, the cells were differentiated and matured into functional neurons by retinoic acid and brain-derived neurotrophic factor. When glutamate was administrated to the cells, both NO and CO increases and subsequent decreases returning to the basal levels were observed with a dual NO/CO microsensor. In order to facilitate sensor’s measurement, a flower-type septuple NO/CO microsensor was newly developed and confirmed in terms of the sensitivity and selectivity. The septuple microsensor was employed for the measurements of NO and CO changes as a function of distances from the position of glutamate injection. Our sensor measurements revealed that only functionally differentiated cells responded to glutamate and released NO and CO.

Effects of mild ozonisation on gene expression and nuclear domains organization in vitro

In the last two decades, the use of ozone (O₃) as a complementary medical approach has progressively been increasing; however, its application is still limited due to the numerous doubts about its possible toxicity, despite the low concentrations used in therapy. For an appropriate and safe clinical application of a potentially toxic agent such as O₃, it is crucial to elucidate the cellular response to its administration. Molecular analyses and transmission electron microscopy were here combined to investigate in vitro the effects of O₃ administration on transcriptional activity and nuclear domains organization of cultured SH-SY5Y neuronal cells; low O₃ concentrations were used as those currently administered in clinical practice. Mild ozonisation did not affect cell proliferation or death, while molecular analyses showed an O₃-induced modulation of some genes involved in the cell response to stress (HMOX1, ERCC4, CDKN1A) and in the transcription machinery (CTDSP1). Ultrastructural cytochemistry after experiments of bromouridine incorporation consistently demonstrated an increased transcriptional rate at both the nucleoplasmic (mRNA) and the nucleolar (rRNA) level. No ultrastructural alteration of nuclear domains was observed. Our molecular, ultrastructural and cytochemical data demonstrate that a mild toxic stimulus such as mild ozonisation stimulate cell protective pathways and nuclear transcription, without altering cell viability. This could possibly account for the positive effects observed in ozone-treated patients.

Carnosic Acid Suppresses the H2O2-Induced Mitochondria-Related Bioenergetics Disturbances and Redox Impairment in SH-SY5Y Cells: Role for Nrf2

The phenolic diterpene carnosic acid (CA, C₂₀H₂₈O₄) exerts antioxidant, anti-inflammatory, anti-apoptotic, and anti-cancer effects in mammalian cells. CA activates the nuclear factor erythroid 2-related factor 2 (Nrf2), among other signaling pathways, and restores cell viability in several in vitro and in vivo experimental models. We have previously reported that CA affords mitochondrial protection against various chemical challenges. However, it was not clear yet whether CA would prevent chemically induced impairment of the tricarboxylic acid cycle (TCA) function in mammalian cells. In the present work, we found that a pretreatment of human neuroblastoma SH-SY5Y cells with CA at 1 μM for 12 h prevented the hydrogen peroxide (H₂O₂)-induced impairment of the TCA enzymes (aconitase, α-ketoglutarate dehydrogenase (α-KGDH), succinate dehydrogenase (SDH)) and abolished the inhibition of the complexes I and V and restored the levels of ATP by a mechanism associated with Nrf2. CA also exhibited antioxidant abilities by enhancing the levels of reduced glutathione (GSH) and decreasing the content oxidative stress markers (cellular 8-oxo-2'-deoxyguanosine (8-oxo-dG), and mitochondrial malondialdehyde (MDA), protein carbonyl, and 3-nitrotyrosine). Silencing of Nrf2 by small interfering RNA (siRNA) abrogated the protective effects elicited by CA in mitochondria of SH-SY5Y cells. Therefore, CA prevented the H₂O₂-triggered mitochondrial impairment by an Nrf2-dependent mechanism. The specific role of Nrf2 in ameliorating the function of TCA enzymes function needs further research.

Intramuscular injection of mechano growth factor E domain peptide regulated expression of memory-related sod, miR-134 and miR-125b-3p in rat hippocampus under simulated weightlessness

OBJECTIVE

To investigate the expression of memory-related antioxidant genes and miRNAs under simulated weightlessness and the regulation of mechano growth factor (MGF) E domain, the peptide preventing nerve damage.

RESULTS

Igf-iea and mgf mRNA levels, expression of antioxidant genes sod1 and sod2 and levels of miR-134 and miR-125b-3p increased in rat hippocampus after 14 days tail suspension to simulate weightlessness which was inhibited with intramuscular injection of E domain peptide. Therefore, administration of MGF E domain peptide could reverse increased expressions of memory-related igf-iea, mgf, sod1, sod2, miR-134 and miR-125b-3p in rat hippocampus under simulated weightlessness.

CONCLUSIONS

MGF may regulate the redox state and miRNA-targeted NR-CREB signaling, and intramuscular injection may be the alternative administration because of its safety, convenience and ability to pass through the blood brain barrier.

20C, a bibenzyl compound isolated from Gastrodia elata, protects PC12 cells against rotenone-induced apoptosis via activation of the Nrf2/ARE/HO-1 signaling pathway

AIM

Our preliminary study shows that a bibenzyl compound isolated from Gastrodia elata, 2-[4-hydroxy-3-(4-hydroxybenzyl)benzyl]-4-(4-hydroxybenzyl)phenol (designated 20C), protects PC12 cells against H2O2-induced injury. In this study we investigated whether 20C exerted neuroprotective action in a cell model of Parkinson's disease.

METHODS

A cell model of Parkinson's disease was established in PC12 cells by exposure to rotenone (4 μmol/L) for 48 h. Cell viability and apoptosis were assessed, and intracellular ROS level and the mitochondrial membrane potential (MMP) were detected. The expression of apoptosis-related proteins Bax, Bcl-2, cytochrome c, cleaved caspase-3, and oxidative stress-related proteins Nrf2, HO-1 and NQO1 were examined using Western blotting. The mRNA levels of HO-1 and NQO1 were determined with RT-PCR. The nuclear translocation of Nrf2 was observed with immunofluorescence staining.

RESULTS

Treatment with rotenone significantly increased the number of apoptotic cells, accompanied by marked increases in the Bax/Bcl-2 ratio, cytochrome c release and caspase-3 activation. Rotenone also increased ROS accumulation, reduced MMP, and increased the nuclear translocation of Nrf2 as well as the mRNA and protein levels of the Nrf2 downstream target genes HO-1 and NQO1 in PC12 cells. Co-treatment with 20C (0.01-1 μmol/L) dose-dependently attenuated rotenone-induced apoptosis and oxidative stress in PC12 cells. Nrf2 knockdown by siRNA partially reversed the protective effects of 20C in rotenone-treated PC12 cells.

CONCLUSION

The bibenzyl compound 20C protects PC12 cells from rotenone-induced apoptosis, at least in part, via activation of the Nrf2/ARE/HO-1 signaling pathway.

Effects of L-carnitine against H2O2-induced oxidative stress in grass carp ovary cells (Ctenopharyngodon idellus)

This study was designed in vitro to investigate the effects of L-carnitine against H2O2-induced oxidative stress in a grass carp (Ctenopharyngodon idellus) ovary cell line (GCO). GCO cells were pre-treated with different concentrations of L-carnitine, followed by incubation with 2.5 mM H2O2 for 1 h to induce oxidative damage. The results indicated that adding L-carnitine at concentrations of 0.01-1 mM into the medium for 12 h significantly increased cell viability. Pre-treatment with L-carnitine at concentrations of 0.1-5 mM for 12 h significantly inhibited 2.5 mM H2O2-induced cell viability loss. The significant decreases in the level of reactive oxygen species and cell apoptosis were observed in 0.5 mM L-carnitine group compared to the H2O2 group. Malondialdehyde values of all of the L-carnitine groups were significantly lower than those of the H2O2 group, while total glutathione levels of all of the L-carnitine groups were significantly higher than of the H2O2 group. The activity of antioxidant enzymes, such as total superoxide dismutase (0.1 and 0.5 mM L-carnitine), catalase (0.5 mM L-carnitine) and γ-glutamyl cysteine synthetase (0.5 and 1 mM L-carnitine), was significantly increased. In addition, pre-treatment of L-carnitine in GCO cells exposed to 2.5 mM H2O2 significantly increased the mRNA expression of copper, zinc superoxide dismutase, catalase (0.5 mM L-carnitine), glutamate cysteine ligase catalytic subunit (0.1-1 mM) and glutathione peroxidase (0.1 mM L-carnitine). In conclusion, L-carnitine promotes GCO cell growth and improves antioxidant function, it plays a protective role against oxidative stress induced by H2O2 in GCO cells, and the appropriate supplemental amount of L-carnitine is 0.1-1 mM.

Dietary choline regulates antibacterial activity, inflammatory response and barrier function in the gills of grass carp (Ctenopharyngodon idella)

An 8-week feeding trial was conducted to determine the effects of graded levels of choline (197-1795 mg/kg) on antibacterial properties, inflammatory status and barrier function in the gills of grass carp. The results showed that optimal dietary choline supplementation significantly improved lysozyme and acid phosphatase activities, complement component 3 (C3) content, and the liver expressed antimicrobial peptide 2 and Hepcidin mRNA levels in the gills of fish (P < 0.05). In addition, appropriate dietary choline significantly decreased the oxidative damage, which might be partly due to increase copper, zinc superoxide dismutase (Cu/Zn-SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and glutathione reductase (GR) activities and increased glutathione content in the gills of fish (P < 0.05). Moreover, appropriate dietary choline significantly up-regulated the mRNA levels of interleukin 10 and transforming growth factor β1, Zonula occludens 1, Occludin, Claudin-b, c, 3 and 12, inhibitor of κBα, target of rapamycin, Cu/Zn-SOD, CAT, GR, GPx, GST and NF-E2-related factor 2 in the gills of fish (P < 0.05). Conversely, appropriate dietary choline significantly down-regulated the mRNA levels of pro-inflammatory cytokines, tumor necrosis factor α, interleukin 8, interferon γ, interleukin 1β, and related signaling factors, nuclear factor kappa B p65, IκB kinase β, IκB kinase γ, myosin light chain kinase and Kelch-like-ECH-associated protein 1a (Keap1a) in the gills of fish (P < 0.05). However, choline did not have a significant effect on the mRNA levels of IκB kinase α, Claudin-15 and Keap1b in the gills of fish. Collectively, appropriate dietary choline levels improved gill antibacterial properties and relative gene expression levels of tight junction proteins, and decreased inflammatory status, as well as up-regulated the mRNA levels of related signaling molecules in the gills of fish. Based on gill C3 content and AHR activity, the dietary choline requirements for young grass carp (266.5-787.1 g) were estimated to be 1191.0 and 1555.0 mg/kg diet, respectively.

Protocatechualdehyde Protects Against Cerebral Ischemia-Reperfusion-Induced Oxidative Injury Via Protein Kinase Cε/Nrf2/HO-1 Pathway

Oxidative stress is closely related to the pathogenesis of ischemic stroke. Protocatechualdehyde (PCA) is a phenolic acid compound that has the putative antioxidant activities. The present study was aimed to investigate the molecular mechanisms involved in the antioxidative effect of PCA against cerebral ischemia/reperfusion (I/R) injury. The experiment stroke model was produced in Sprague-Dawley rats via middle cerebral artery occlusion (MCAO). To model ischemia-like conditions in vitro, differentiated SH-SY5Y cells were exposed to transient oxygen and glucose deprivation (OGD). Treatment with PCA significantly improved neurologic score, reduced infarct volume and necrotic neurons, and also decreased reactive oxygen species (ROS) production, 4-hydroxynonenal (4-HNE), and 8-hydroxy-2'-deoxyguanosine (8-OHdG) contents at 24 h after reperfusion. Meanwhile, PCA significantly increased the transcription nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) expressions in the ischemic cerebral cortex as shown by immunofluorescence staining and Western blot analysis. In vitro experiment showed that PCA protected differentiated SH-SY5Y cells against OGD-induced injury. Likewise, PCA also increased markedly the Nrf2 and HO-1 expressions in a dose-dependent manner. The neuroprotection effect of PCA was abolished by knockdown of Nrf2 and HO-1. Moreover, knockdown of protein kinase Cε (PKCε) also blocked PCA-induced Nfr2 nuclear translocation, HO-1 expression, and neuroprotection. Taken together, these results provide evidences that PCA can protect against cerebral ischemia-reperfusion-induced oxidative injury, and the neuroprotective effect involves the PKCε/Nrf2/HO-1 pathway.

Localized delivery of mechano-growth factor E-domain peptide via polymeric microstructures improves cardiac function following myocardial infarction

The Insulin like growth factor-I isoform mechano-growth factor (MGF), is expressed in the heart following myocardial infarction and encodes a unique E-domain region. To examine E-domain function, we delivered a synthetic peptide corresponding to the unique E-domain region of the human MGF (IGF-1Ec) via peptide eluting polymeric microstructures to the heart. The microstructures were made of poly (ethylene glycol) dimethacrylate hydrogel and bioengineered to be the same size as an adult cardiac myocyte (100 × 15 × 15 μm) and with a stiffness of 20 kPa. Peptide eluting microrods and empty microrods were delivered via intramuscular injection following coronary artery ligation in mice. To examine the physiologic consequences, we assessed the impact of peptide delivery on cardiac function and cardiovascular hemodynamics using pressure-volume loops and gene expression by quantitative RT-PCR. A significant decline in both systolic and diastolic function accompanied by pathologic hypertrophy occurred by 2 weeks which decompensated further by 10 weeks post-infarct in the untreated groups. Delivery of the E-domain peptide eluting microrods decreased mortality, ameliorated the decline in hemodynamics, and delayed decompensation. This was associated with the inhibition of pathologic hypertrophy despite increasing vascular impedance. Delivery of the empty microrods had limited effects on hemodynamics and while pathologic hypertrophy persisted there was a decrease in ventricular stiffness. Our data show that cardiac restricted administration of the MGF E-domain peptide using polymeric microstructures may be used to prevent adverse remodeling of the heart and improve function following myocardial infarction.

Pinocembrin attenuates 6-OHDA-induced neuronal cell death through Nrf2/ARE pathway in SH-SY5Y cells

Pinocembrin (PB), the most abundant flavonoid in propolis, has been known to display antioxidant activity. However, the mechanism as how PB can induce antioxidant activity remains elusive. The purpose of the present study was to investigate the potential neuroprotective role of PB and to delineate its mechanism of action against the Parkinson's disease-related neurotoxin 6-hydroxydopamine(6-OHDA)-induced cell death in neuroblastoma SH-SY5Y cells. Results indicate that pretreatment with PB for 4 h significantly reduced the 6-OHDA-induced cell viability loss, apoptotic rate and decreased Bcl-2/Bax ratio. In addition, PB inhibited 6-OHDA-induced oxidative stress as measured by the formation of reactive oxygen species, the level of malondialdehyde, mitochondrial membrane potential, and superoxide dismutase. Moreover, we have revealed the PB treatment resulted in an increase in nuclear factor E2-related factor 2 (Nrf2) protein levels and subsequent activation of antioxidant response element (ARE) pathway genes of heme oxygenase-1 (HO-1) and γ-glutamylcysteine synthetase (γ-GCS) in SH-SY5Y cells. Treatment of SH-SY5Y cells with Nrf2 small interference RNA abolished PB-induced HO-1 and γ-GCS expression and its protective effects. Taken together, these findings suggest that PB can protect the SH-SY5Y cells from 6-OHDA-induced oxidative cell death via Nrf2/ARE pathway. Thus, our study indicates that PB has a partial cytoprotective role in dopaminergic cell culture systems.

Role of NF-E2-related factor 2 in neuroprotective effect of l-carnitine against high glucose-induced oxidative stress in the retinal ganglion cells

l-Carnitine (LC) has protective effects on high glucose-induced oxidative stress in the retinal ganglion cells (RGCs). The aim of this study was to investigate the role of NF-E2-related factor 2 (Nrf2), Kelch like-ECH-associated protein 1 (Keap1), haemoxygenase-1 (HO-1) and γ-glutamyl cysteine synthetase (γ-GCS) in the protective effect of LC on RGCs. RGCs were first processed with high concentrations of glucose. LC treatment at three concentrations (50μM, 100μM and 200μM) was applied to high glucose stimulated RGCs. The expression of Nrf2, Keap1, haemoxygenase-1 (HO-1) and γ-glutamyl cysteine synthetase (γ-GCS) was quantified by Western blot in the treatment and control (high glucose stimulation) groups. In the three LC groups (50μM, 100μM and 200μM), Nrf-2 (0.71±0.04, 0.89±0.05, 1.24±0.05 vs 0.56±0.03, p<0.05), HO-1 (0.58±0.04, 0.76±0.06, 0.89±0.07 vs 0.25±0.03, p<0.01), and γ-GCS protein expression (0.66±0.03, 0.79±0.05, 0.84±0.08 vs 0.84±0.08, p<0.01) was higher than in the control group. The levels of Keap1 protein were in the LC groups were lower than in the control group (0.50±0.03, 0.45±0.02, 0.53±0.03 vs 0.86±0.05, p<0.01). In conclusion, in high glucose stimulated RGCs, LC treatment was associated with an increased level of Nrf2, HO-1and γ-GCS. LC treatment was also associated with a reduced expression of Keap1 protein. These results suggest that the protective effect of LC treatment on RGCs may be related to Nrf2-Keap1 pathway.

Sevoflurane post-conditioning increases nuclear factor erythroid 2-related factor and haemoxygenase-1 expression via protein kinase C pathway in a rat model of transient global cerebral ischaemia

BACKGROUND

The antioxidant mechanism of sevoflurane post-conditioning-induced neuroprotection remains unclear. We determined whether sevoflurane post-conditioning induces nuclear factor erythroid 2-related factor (Nrf2, a master transcription factor regulating antioxidant defence genes) and haemoxygenase-1 (HO-1, an antioxidant enzyme) expression, and whether protein kinase C (PKC) is involved in Nrf2 activation, in a rat model of transient global cerebral ischaemia/reperfusion (I/R) injury.

METHODS

Eighty-six rats were assigned to five groups: sham (n=6), control (n=20), sevoflurane post-conditioning (two cycles with 2 vol% sevoflurane inhalation for 10 min, n=20), chelerythrine (a PKC inhibitor; 5 mg kg(-1) i.v. administration, n=20), and sevoflurane post-conditioning plus chelerythrine (n=20). The levels of nuclear Nrf2 and cytoplasmic HO-1 were assessed 1 or 7 days after ischaemia (n=10 each, apart from the sham group, n=3).

RESULTS

On day 1 but not day 7 post-ischaemia, Nrf2 and HO-1 expression were significantly higher in the sevoflurane post-conditioning group than in the control group. Chelerythrine administration reduced the elevated Nrf2 and HO-1 expression induced by sevoflurane post-conditioning.

CONCLUSIONS

Sevoflurane post-conditioning increased Nrf2/HO-1 expression via PKC signalling in the early phase after transient global cerebral I/R injury, suggesting that activation of antioxidant enzymes may be responsible for sevoflurane post-conditioning-induced neuroprotection in the early phase after cerebral I/R injury.

The complexity of the IGF1 gene splicing, posttranslational modification and bioactivity

The insulinlike growth factor-I (IGF-I) is an important factor which regulates a variety of cellular responses in multiple biological systems. The IGF1 gene comprises a highly conserved sequence and contains six exons, which give rise to heterogeneous mRNA transcripts by a combination of multiple transcription initiation sites and alternative splicing. These multiple transcripts code for different precursor IGF-I polypeptides, namely the IGF-IEa, IGF-IEb and IGF-IEc isoforms in humans, which also undergo posttranslational modifications, such as proteolytic processing and glycosylation. IGF-I actions are mediated through its binding to several cell-membrane receptors and the IGF-I domain responsible for the receptor binding is the bioactive mature IGF-I peptide, which is derived after the posttranslational cleavage of the pro-IGF-I isoforms and the removal of their carboxy-terminal E-peptides (that is, the Ea, Eb and Ec). Interestingly, differential biological activities have been reported for the different IGF-I isoforms, or for their E-peptides, implying that IGF-I peptides other than the IGF-I ligand also possess bioactivity and, thus, both common and unique or complementary pathways exist for the IGF-I isoforms to promote biological effects. The multiple peptides derived from IGF-I and the differential expression of its various transcripts in different conditions and pathologies appear to be compatible with the distinct cellular responses observed to the different IGF-I peptides and with the concept of a complex and possibly isoform-specific IGF-I bioactivity. This concept is discussed in the present review, in the context of the broad range of modifications that this growth factor undergoes which might regulate its mechanism(s) of action.

Neuroprotective effects of Hu-Yi-Neng, a diet supplement, on SH-SY5Y human neuroblastoma cells

OBJECTIVES

Oxidative stress is considered the potential risk to the development of dementia. Some medicines, vitamins, and diet supplements have been suggested to have possible benefits via the antioxidative effects to slow the decline of cognitive function in demented and non-demented individuals. However, few studies were conducted to examine their functions, especially in composite diet supplements. Hu-Yi-Neng is a composite diet supplement, including ginkgo biloba, extract of pine bark, phosphatidyl serine, docosahexaenoic acid, and folic acid, used extensively in Taiwan. Therefore, our aim is to investigate the potential protective effects of Hu-Yi-Neng on human neuron cells. MATERALS AND METHODS: H2O2-induced neuronal toxicity was characterized in SH-SY5Y human neuroblastoma cells by the decrease of cell viability using PrestoBlue™ assay and by the increase of intracellular reactive oxygen species (ROS) level using DCFH-DA (2', 7'-dichlorodihydrofluorescin diacetate) assays. HO-1 mRNA expression was detected by real-time PCR. Akt and Erk 1/2 proteins were detected by western blotting.

RESULTS

Pretreatment with Hu-Yi-Neng significantly reversed the decrease in cell viability induced by H2O2 in SH-SY5Y cells. Furthermore, Hu-Yi-Neng dose-dependently suppressed the elevation of intracellular reactive oxygen species (ROS) level. Hu-Yi-Neng protected SH-SY5Y cells from oxidative stress may via the increase in mRNA expression of heme oxygenase-1 (HO-1), an antioxidant enzyme. In addition, Hu-Yi-Neng inhibited H2O2-induced phosphorylation of Akt kinase but further increased the phosphorylation of Erk 1/2.

CONCLUSION

Our results suggest that Hu-Yi-Neng has protective effect against oxidative stress-induced neuron cell loss and it could be an ideal composite diet supplement for preventing neurodegenerative diseases.

The E-domain region of mechano-growth factor inhibits cellular apoptosis and preserves cardiac function during myocardial infarction

Insulin-like growth factor-1 (IGF-1) isoforms are expressed via alternative splicing. Expression of the minor isoform IGF-1Eb [also known as mechano-growth factor (MGF)] is responsive to cell stress. Since IGF-1 isoforms differ in their E-domain regions, we are interested in determining the biological function of the MGF E-domain. To do so, a synthetic peptide analog was used to gain mechanistic insight into the actions of the E-domain. Treatment of H9c2 cells indicated a rapid cellular uptake mechanism that did not involve IGF-1 receptor activation but resulted in a nuclear localization. Peptide treatment inhibited the intrinsic apoptotic pathway in H9c2 cells subjected to cell stress with sorbitol by preventing the collapse of the mitochondrial membrane potential and inhibition of caspase-3 activation. Therefore, we administered the peptide at the time of myocardial infarction (MI) in mice. At 2 weeks post-MI cardiac function, gene expression and cell death were assayed. A significant decline in both systolic and diastolic function was evident in untreated mice based on PV loop analysis. Delivery of the E-peptide ameliorated the decline in function and resulted in significant preservation of cardiac contractility. Associated with these changes were an inhibition of pathologic hypertrophy and significantly fewer apoptotic nuclei in the viable myocardium of E-peptide-treated mice post-MI. We conclude that administration of the MGF E-domain peptide may provide a means of modulating local tissue IGF-1 autocrine/paracrine actions to preserve cardiac function, prevent cell death, and pathologic remodeling in the heart.

The octadecaneuropeptide ODN prevents 6-hydroxydopamine-induced apoptosis of cerebellar granule neurons through a PKC-MAPK-dependent pathway

Oxidative stress, induced by various neurodegenerative diseases, initiates a cascade of events leading to apoptosis, and thus plays a critical role in neuronal injury. In this study, we have investigated the potential neuroprotective effect of the octadecaneuropeptide (ODN) on 6-hydroxydopamine (6-OHDA)-induced oxidative stress and apoptosis in cerebellar granule neurons (CGN). ODN, which is produced by astrocytes, is an endogenous ligand for both central-type benzodiazepine receptors (CBR) and a metabotropic receptor. Incubation of neurons with subnanomolar concentrations of ODN (10⁻¹⁸ to 10⁻¹² M) inhibited 6-OHDA-evoked cell death in a concentration-dependent manner. The effect of ODN on neuronal survival was abrogated by the metabotropic receptor antagonist, cyclo₁₋₈ [DLeu⁵]OP, but not by a CBR antagonist. ODN stimulated polyphosphoinositide turnover and ERK phosphorylation in CGN. The protective effect of ODN against 6-OHDA toxicity involved the phospholipase C/ERK MAPK transduction cascade. 6-OHDA treatment induced an accumulation of reactive oxygen species, an increase of the expression of the pro-apoptotic gene Bax, a drop of the mitochondrial membrane potential and a stimulation of caspase-3 activity. Exposure of 6-OHDA-treated cells to ODN blocked all the deleterious effects of the toxin. Taken together, these data demonstrate for the first time that ODN is a neuroprotective agent that prevents 6-OHDA-induced oxidative stress and apoptotic cell death.

Administration of a Synthetic Peptide Derived from the E-domain Region of Mechano-Growth Factor Delays Decompensation Following Myocardial Infarction

Insulin like growth factor-I (IGF-1) isoforms differ structurally in their E-domain regions and their temporal expression profile in response to injury. We and others have reported that Mechano-growth factor (MGF), which is equivalent to human IGF-1c and rodent IGF-1Eb isoforms, is expressed acutely following myocardial infarction (MI) in the mouse heart. To examine the function of the E-domain region, we have used a stabilized synthetic peptide analog corresponding to the unique 24 amino acid region E-domain of MGF. Here we deliver the human MGF E-domain peptide to mice during the acute phase (within 12 hours) and the chronic phase (8 weeks) post-MI. We assessed the impact of peptide delivery on cardiac function and cardiovascular hemodynamics by pressure-volume (P-V) loop analysis and gene expression by quantitative RT-PCR. A significant decline in both systolic and diastolic hemodynamics accompanied by pathologic hypertrophy occurred by 10 weeks post-MI in the untreated group. Delivery of the E-domain peptide during the acute phase post-MI ameliorated the decline in hemodynamics, delayed decompensation but did not prevent pathologic hypertrophy. Delivery during the chronic phase post-MI significantly improved systolic function, predominantly due to the effects on vascular resistance and prevented decompensation. While pathologic hypertrophy persisted there was a significant decline in atrial natriuretic factor (ANF) expression in the E-domain peptide treated hearts. Taken together our data suggest that administration of the MGF E-domain peptide derived from the propeptide form of IGF-1Ec may be used to facilitate the actions of IGF-I produced by the tissue during the progression of heart failure to improve cardiovascular function.

Evidence for the Possible Biological Significance of the igf-1 Gene Alternative Splicing in Prostate Cancer

Insulin-like growth factor-I (IGF-I) has been implicated in the pathogenesis of prostate cancer (PCa), since it plays a key role in cell proliferation, differentiation, and apoptosis. The IGF-I actions are mediated mainly via its binding to the type I IGF receptor (IGF-IR), however IGF-I signaling via insulin receptor (IR) and hybrid IGF-I/IR is also evident. Different IGF-I mRNA splice variants, namely IGF-IEa, IGF-IEb, and IGF-IEc, are expressed in human cells and tissues. These transcripts encode several IGF-I precursor proteins which contain the same bioactive product (mature IGF-I), however, they differ by the length of their signal peptides on the amino-terminal end and the structure of the extension peptides (E-peptides) on the carboxy-terminal end. There is an increasing interest in the possible different role of the IGF-I transcripts and their respective non-(mature)IGF-I products in the regulation of distinct biological activities. Moreover, there is strong evidence of a differential expression profile of the IGF-I splice variants in normal versus PCa tissues and PCa cells, implying that the expression pattern of the various IGF-I transcripts and their respective protein products may possess different functions in cancer biology. Herein, the evidence that the IGF-IEc transcript regulates PCa growth via Ec peptide specific and IGF-IR/IR-independent signaling is discussed.

Desipramine protects neuronal cell death and induces heme oxygenase-1 expression in Mes23.5 dopaminergic neurons

BACKGROUND

Desipramine is known principally as a tricyclic antidepressant drug used to promote recovery of depressed patients. It has also been used in a number of other psychiatric and medical conditions. The present study is the first to investigate the neuroprotective effect of desipramine.

METHODOLOGY/PRINCIPAL FINDINGS

Mes23.5 dopaminergic cells were used to examine neuroprotective effect of desipramine. Western blot, reverse transcription-PCR, MTT assay, siRNA transfection and electrophoretic mobility shift assay (EMSA) were carried out to assess the effects of desipramine. Desipramine induces endogenous anti-oxidative enzyme, heme oxygenase-1 (HO-1) protein and mRNA expression in concentration- and time-dependent manners. A different type of antidepressant SSRI (selective serotonin reuptake inhibitor), fluoxetine also shows similar effects of desipramine on HO-1 expression. Moreover, desipramine induces HO-1 expression through activation of ERK and JNK signaling pathways. Desipramine also increases NF-E2-related factor-2 (Nrf2) accumulation in the nucleus and enhances Nrf2-DNA binding activity. Moreover, desipramine-mediated increase of HO-1 expression is reduced by transfection with siRNA against Nrf2. On the other hand, pretreatment of desipramine protects neuronal cells against rotenone- and 6-hydroxydopamine (6-OHDA)-induced neuronal death. Furthermore, inhibition of HO-1 activity by a HO-1 pharmacological inhibitor, ZnPP IX, attenuates the neuroprotective effect of desipramine. Otherwise, activation of HO-1 activity by HO-1 activator and inducer protect 6-OHDA-induced neuronal death.

CONCLUSIONS/SIGNIFICANCE

These findings suggest that desipramine-increased HO-1 expression is mediated by Nrf2 activation through the ERK and JNK signaling pathways. Our results also suggest that desipramine provides a novel effect of neuroprotection, and neurodegenerative process might play an important role in depression disorder.

Osteopontin increases heme oxygenase-1 expression and subsequently induces cell migration and invasion in glioma cells

Malignant gliomas are associated with high morbidity and mortality because they are highly invasive into surrounding brain tissue, making complete surgical resection impossible. Osteopontin is abundantly expressed in the brain and is involved in cell adhesion, migration, and invasion. The aim of the present study was to investigate the mechanisms of glioma cell migration. Migration and invasion activity were determined by transwell and wound-healing assays. Gene and protein expressions were analyzed by reverse transcription-PCR, real time-PCR, and Western blotting. Nrf2-DNA binding activity was determined by electrophoretic mobility shift assay. Establishment of migration-prone sublines were performed to select highly migratory glioma. An intracranial xenograft mouse model was used for the in vivo study. Application of recombinant human osteopontin enhanced the migration of glioma cells. Expression of heme oxygenase (HO)-1 mRNA and protein also increased in response to osteopontin stimulation. Osteopontin-induced increase in cell migration was antagonized by HO-1 inhibitor or HO-1 small interfering (si)RNA. Osteopontin-mediated HO-1 expression was reduced by treatment with MEK/ERK and phosphatidylinositol 3-kinase/Akt inhibitors, as well as siRNA against Nrf2. Furthermore, osteopontin stimulated Nrf2 accumulation in the nucleus and increased Nrf2-DNA binding activity. In migration-prone sublines, cells with greater migration ability had higher osteopontin and HO-1 expression, and zinc protoporphyrin IX treatment could effectively reduce the enhanced migration ability. In an intracranial xenograft mouse model, transplantation of migration-prone subline cells exhibited higher cell migration than parental tumor cells. These results indicate that osteopontin activates Nrf2 signaling, resulting in enhanced HO-1 expression and cell migration in glioma cells.

RETRACTED: S-allyl cysteine protects against 6-hydroxydopamine-induced neurotoxicity in the rat striatum: involvement of Nrf2 transcription factor activation and modulation of signaling kinase cascades

Pharmacological activation at the basal ganglia of the transcription factor Nrf2, guardian of redox homeostasis, holds a strong promise for the slow progression of Parkinson's disease (PD). However, a potent Nrf2 activator in the brain still must be found. In this study, we have investigated the potential use of the antioxidant compound S-allyl cysteine (SAC) in the activation of Nrf2 in 6-hydoxydopamine (6-OHDA)-intoxicated rats. In the rat striatum, SAC by itself promoted the Nrf2 dissociation of Keap-1, its nuclear translocation, the subsequent association with small MafK protein, and further binding of the Nrf2/MafK complex to ARE sequence, as well as the up-regulation of Nrf2-dependent genes encoding the antioxidant enzymes HO-1, NQO-1, GR, and SOD-1. In vivo and in vitro experiments to identify signaling pathways activated by SAC pointed to Akt as the most likely kinase participating in Nrf2 activation by SAC. In PC12 cells, SAC stimulated the activation of Akt and ERK1/2 and inhibited JNK1/2/3 activation. In the rat striatum, the SAC-induced activation of Nrf2 is likely to contribute to inhibit the toxic effects of 6-OHDA evidenced by phase 2 antioxidant enzymes up-regulation, glutathione recovery, and attenuation of reactive oxygen species (ROS), nitric oxide (NO), and lipid peroxides formation. These early protective effects correlated with the long-term preservation of the cellular redox status, the striatal dopamine (DA) and tyrosine hydroxylase (TH) levels, and the improvement of motor skills. Therefore, this study indicates that, in addition to direct scavenging actions, the activation of Nrf2 by SAC might confer neuroprotective responses through the modulation of kinase signaling pathways in rodent models of PD, and suggests that this antioxidant molecule may have a therapeutic value in this human pathology.

New proangiogenic activity on vascular endothelial cells for C-terminal mechano growth factor

Angiogenesis is crucial in wound healing. The administration of the C-terminal 24-a.a. peptide of mechano growth factor (MGF24E) has been previously demonstrated to induce more blood vessels in regenerating bone around defective areas compared with the control. Accordingly, this study aims to determine whether MGF24E promotes bone defect healing through MGF24E-increased angiogenesis and whether MGF24E has positive effects on angiogenesis in vitro. The roles of MGF24E on angiogenesis and the underlying mechanisms were investigated. The cell proliferation, migration, and tubulogenesis of the human vascular endothelial EA.hy926 cells co-treated with 2% serum and MGF24E were determined to assess angiogenesis in comparison with 100 ng/ml of vascular endothelial growth factor 165 (VEGF(165))-positive control or vehicle control (phosphate-buffered saline). MGF24E treatment (10 ng/ml) significantly promoted the biological processes of angiogenesis on EA.hy926 cells compared with the vehicle control. The suppression of vascular endothelial growth factor and angiopoietin-I expressions by 2% serum starvation was reversed by the addition of 10 ng/ml of MGF24E in 2% serum medium. This result suggests that MGF24E has a protective effect on angiogenesis. Moreover, the inhibition of ERK due to PD98050 pretreatment completely abolished and mostly blocked MGF24E-induced proliferation and migration, respectively, whereas the MGF24-induced tubulogenesis and the angiogenic factor expression were only partially inhibited. These new findings suggest that MGF24E promotes angiogenesis by enhancing the expression of angiogenic cytokines which involves the MAPK/ERK-signaling pathway.

Mechano-growth factor E peptide inhibits the differentiation and mineralization of osteoblasts

OBJECTIVE

To investigate the effects of mechano-growth factor E (MGF-E) peptide derived from an IGF-1 isoform on the differentiation and mineralization of osteoblasts.

METHODS

MGF-E peptide corresponding to the carboxy terminal 24 amino acid peptide of human MGF was synthesized. MGF-E (1 nM) peptide was then used to treat the pre-osteoblast line MC3T3-E1. At predetermined times, alkaline phosphatase (ALP) activity was quantified using an enzyme activity assay kit. The expression levels of collagen I (Col I) and osteopontin (OPN), and core binding factor 1 (Cbfα-1) were detected by reverse transcription polymerase chain reaction and Western blot analysis. The effect of MGF-E on mineralization was determined by Alizarin Red staining and calcium concentration analysis. The kinase inhibitor PD98059 was used to investigate Erk pathway involvement in the MGF-E role.

RESULTS

In the MGF-E-treated osteoblasts, ALP activity decreased with increased Erk activation. The transcription and translation of Col I were inhibited, but those of OPN were enhanced. PD98059 abolished the inhibitory effect and increased the expression of Col I, but decreased that of OPN. Treatment with MGF-E alone up-regulated the mRNA and total protein levels of Cbfα-1, but decreased the fraction of activated Cbfα-1 in the nucleus. Mineralization was delayed by MGF-E, as shown by the bone nodule staining and calcium concentration analysis. These delayed actions were weakened after treatment with PD98059.

CONCLUSIONS

MGF-E could inhibit osteoblast differentiation and mineralization. The possible mechanisms are increased Erk activity and decreased Cbfα-1 nuclear translocation.