Glutathione intensifies gliotoxin-induced cytotoxicity in human neuroblastoma SH-SY5Y cells

Gliotoxin is a fungal second metabolite produced by diverse species that can be found in compost, stored crops, moist animal feed and sawdust. The role of glutathione in gliotoxin-induced toxicity was studied in order to elucidate the toxic mechanisms leading to neurite degeneration and cell death in differentiated human neuroblastoma (SH-SY5Y) cells. After 72 h of exposure to gliotoxin, moderate cytotoxicity was induced at 0.1 μmol/L, which was more severe at higher concentrations. A reduction in the number of neurites per cell was also observed. By decreasing the level of intracellular glutathione with l-buthionine-sulfoxamine (BSO) a specific inhibitor of glutathione synthesis, the cytotoxic effect of gliotoxin was significantly attenuated. The gliotoxin-induced cytotoxicity was also slightly reduced by the antioxidant vitamin C. However, the neurite degenerative effect was not altered by BSO, or by vitamin C. A concentration-dependent increase in the ratio between oxidized and reduced forms of glutathione, as well as the total intracellular glutathione levels, was noted after exposure to gliotoxin. The increase of glutathione was also reflected in western blot analyses showing a tendency for the regulatory subunit of γ-glutamylcysteine synthetase to be upregulated. In addition, the activity of glutathione reductase was slightly increased in gliotoxin-exposed cells. These results indicate that glutathione promotes gliotoxin-induced cytotoxicity, probably by reducing the ETP (epipolythiodioxopiperazine) disulfide bridge to the dithiol form.     

The prevention of the staurosporine-induced apoptosis by Bcl-XL, but not by Bcl-2 or caspase inhibitors, allows the extensive differentiation of human neuroblastoma cells

Staurosporine is one of the best apoptotic inducers in different cell types including neuroblastomas. In this study we have compared the efficiency and final outcome of three different anti-apoptotic strategies in staurosporine-treated SH-SY5Y human neuroblastoma cells. At staurosporine concentrations up to 500 nm, z-VAD.fmk a broad-spectrum, noncompetitive inhibitor of caspases, reduced apoptosis in SH-SY5Y cells. At higher concentrations, z-VAD.fmk continued to inhibit caspases and the apoptotic phenotype but not cell death which seems to result from oxidative damage. Stable over-expression of Bcl-2 in SH-SY5Y protected cells from death at doses of staurosporine up to 1 microm. At higher doses, cytochrome c release from mitochondria occurred, caspases were activated and cells died by apoptosis. Therefore, we conclude that Bcl-2 increased the threshold for apoptotic cell death commitment. Over-expression of Bcl-X(L) was far more effective than Bcl-2. Bcl-X(L) transfected cells showed a remarkable resistance staurosporine-induced cytochrome c release and associated apoptotic changes and survived for up to 15 days in 1 microm staurosporine. In these conditions, SH-SY5Y displayed a remarkable phenotype of neuronal differentiation as assessed by neurite outgrowth and expression of neurofilament, Tau and MAP-2 neuronal specific proteins.     

Constitutive expression and cytoplasmic compartmentalization of ATM protein in differentiated human neuron-like SH-SY5Y cells

Ataxia telangiectasia (A-T) is an autosomal, recessive disorder mainly characterized by neuronal degeneration. However, the reason for neuronal degeneration in A-T patients is still unclear. ATM (A-T, mutated), the gene mutated in A-T, encodes a 370-kDa protein kinase. We measured the levels of the ATM protein found in differentiated neuron-like rat PC12 cells and differentiated neuron-like human SH-SY5Y cells. We found that, in rat PC12 cells, ATM levels decreased dramatically after differentiation, which is consistent with previous results observed in differentiated mouse neural progenitor cells. In contrast, the levels of ATM were similar before and after differentiation in human SH-SY5Y cells. Using an indirect immunofluorescence assay, we showed that ATM translocates from the nucleus to the cytoplasm in differentiated human SH-SY5Y cells. The translocation of ATM was further verified by subcellular fractionation experiments. The constitutive expression and cytoplasmic translocation of ATM in differentiated SH-SY5Y cells suggest that ATM is important for maintaining the regular function of human neuronal cells. Our results further demonstrated that, in response to insulin, ATM protects differentiated neuron-like SH-SY5Y cells from serum starvation-induced apoptosis. These data provide the first evidence that cytoplasmic ATM promotes survival of human neuronal cells in an insulin-dependent manner.     

Acrylamide-induced effects on general and neurospecific cellular functions during exposure and recovery

Basal cytotoxicity, morphological changes and alterations in cell physiological and neurochemical functions were studied in differentiated human neuroblastoma (SH-SY5Y) cells during exposure to acrylamide and during a subsequent recovery period after cessation of exposure. Acrylamide induced a 20% reduction in the number of neurites per cell at 0.21 mmol/L and 20% decrease in the protein synthesis rate at 0.17 mmol/L after 72 h of exposure. Furthermore, the basal level of intracellular calcium concentration ([Ca²⁺]_i) and receptor-activated (carbachol, 0.1 mmol/L) Ca²⁺ fluxes increased by 49% and 21%, respectively, at 0.25 mmol/L. These observations were made at noncytotoxic acrylamide concentrations, signifying specific neurotoxic alterations. Forty-eight hours after cessation of acrylamide exposure, the SH-SY5Y cells had recovered, i.e., the number of neurites per cell as well as the basal level of [Ca²⁺]_i and rate of protein synthesis were comparable to those of control cells. The general calpain inhibitor calpeptin decreased the acrylamide-induced (0.5 mmol/L) neurite degeneration, determined as reduction in number of neurites per cell, from 52% to 17% as compared to control cells, which further supports the hypothesis that an increased [Ca²⁺]_i plays a significant role for acrylamide-induced axonopathy.     

The radical scavenger CR-6 protects SH-SY5Y neuroblastoma cells from oxidative stress-induced apoptosis: effect on survival pathways

Reactive oxygen species (ROS) and oxidative stress have long been linked to cell death of neurons in many neurodegenerative conditions. However, the exact molecular mechanisms triggered by oxidative stress in neurodegeneration are at present unclear. In the current work we have used the human neuroblastoma SH-SY5Y cell line as a model for studying the molecular events occurring after inducing apoptosis with H2O2. We show that treatment of SH-SY5Y cells with H2O2 up-regulates survival pathways during early stages of apoptosis. Subsequently, the decline of anti-apoptotic protein levels leads to the activation of the calcium-dependent proteases calpains and the cysteine proteases caspases. Additionally, we demonstrate that CR-6 (3,4-dihydro-6-hydroxy-7-methoxy-2,2-dimethyl-1(2H)-benzopyran) acts as a scavenger of ROS and prevents apoptosis by enhancing and prolonging up-regulation of survival pathways. Furthermore, we show that pre-treatment of SH-SY5Y cells with a cocktail containing CR-6, the pan-caspase inhibitor zVAD-fmk (zVal-Ala-Asp-fluoro-methylketone) and the calpain inhibitor SJA6017 confers almost total protection against apoptosis. In summary, the present work characterizes the molecular mechanisms involved in oxidative stress-induced apoptosis in SH-SY5Y cells. Our findings highlight the relevance of CR-6, alone or in combination with other drugs, as potential therapeutic strategy for the treatment of neurodegenerative diseases.     

Role of autophagy in G2019S-LRRK2-associated neurite shortening in differentiated SH-SY5Y cells

Neuritic retraction represents a prominent feature of the degenerative phenotype associated with mutations in leucine rich repeat kinase 2 (LRRK2) that are implicated in autosomal dominant and some cases of sporadic Parkinson's disease. Alterations in macroautophagy, the vacuolar catabolism of cytoplasmic constituents, have been described in Parkinson's disease. In this study, we utilized retinoic-acid differentiated SH-SY5Y cells to determine whether autophagy contributes to mutant LRRK2-associated neurite degeneration. Transfection of pre-differentiated SH-SY5Y cells with LRRK2 cDNA containing the common G2019S mutation resulted in significant decreases in neurite length, which were not observed in cells transfected with wild type LRRK2 or its kinase-dead K1906M mutation. G2019S LRRK2 transfected cells also exhibited striking increases in autophagic vacuoles in both neuritic and somatic compartments, as demonstrated by fluorescence and western blot analysis of the autophagy marker green fluorescent protein-tagged microtubule-associated protein Light Chain 3 and by transmission electron microscopy. RNA interference knockdown of LC3 or Atg7 , two essential components of the conserved autophagy machinery, reversed the effects of G2019S LRRK2 expression on neuronal process length, whereas rapamycin potentiated these effects. The mitogen activated protein kinase/extracellular signal regulated protein kinase (MAPK/ERK) kinase (MEK) inhibitor 1,4-diamino-2,3-dicyano-1,4-bis[2-aminophenylthio]butadiene (U0126) reduced LRRK2-induced neuritic autophagy and neurite shortening, implicating MAPK/ERK-related signaling. These results indicate an active role for autophagy in neurite remodeling induced by pathogenic mutation of LRRK2.     

Identification of twinfilin-2 as a factor involved in neurite outgrowth by RNAi-based screen

Using RNA interference (RNAi) to suppress gene expression, we attempted to identify tyrosine kinases involved in the extension of neurites from SH-SY5Y cells. A comprehensive analysis of gene “knock-down” profiles with small interfering RNAs (siRNAs) revealed candidate proteins that might control neurite extension. Phenotype-based screening of differentiating SH-SY5Y cells following retinoic acid (RA) stimulation indicated that twinfilin-2 is a protein that is involved in neurite outgrowth, as confirmed by morphological analysis of twinfilin-2-overexpressing cells.     

应用两种方法诱导SH-SY5Y细胞分化的研究

目的：观察全反式维甲酸（ATRA）处理和ATRA与十四烷酰佛波醇乙酸酯（TPA）序贯处理（ATRA/TPA）对人类神经母细胞瘤细胞系SH-SY5Y细胞增殖抑制和形态分化的影响。方法：应用10μM ATRA处理6天和10μM ATRA处理3天继以80 nMTPA处理3天这两种方法使SH-SY5Y细胞分化;用倒置光学显微镜动态观察SH-SY5Y细胞形态学变化;并用MTT比色法比较两种分化方法对SH-SY5Y细胞的体外抗增殖作用。结果：ATRA处理和ATRA与TPA序贯处理对SH-SY5Y细胞都有抗增值和诱导细胞分化作用,细胞形态发生明显的变化,分化成神经元表型,前者主要表现为两端带有长突起的纺锤体样细胞形态,而后者主要是由细胞体延伸出多个突起的多边形的细胞。ATRA分化6天的细胞的存活率下降为78.7%±2.0%。当去除ATRA后,继续培养1天的细胞存活率上升为89%±0.2%,而继续培养2天的细胞存活率为86.3%±1.4%;ATRA与TPA序贯分化6天细胞存活率下降为75.9±0.4%。当去除TPA后,继续培养一天的细胞存活率为75.5±0.7%,继续培养2天的细胞存活率为74.9±1.0%。结论：维甲酸（ATRA）处理和ATRA与十四烷酰佛波醇乙酸酯（TPA）序贯处理（ATRA/TPA）均能明显诱导SH-SY5Y细胞分化。这两种分化细胞为神经科学的研究提供了优良的体外培养模型细胞,尤其是ATRA与TPA序贯处理能获得分化完全而稳定的神经元样细胞。     

The retinoic acid and brain-derived neurotrophic factor differentiated SH-SY5Y cell line as a model for Alzheimer's disease-like tau phosphorylation

The paired helical filaments of highly phosphorylated tau protein are the main components of neurofibrillary tangles (NFT) in Alzheimer's disease (AD). Protein kinases including glycogen synthase kinase 3 beta (GSK3beta), cyclin-dependent kinase 5 (Cdk5), and c-Jun N-terminal kinase (JNK) have been implicated in NFT formation making the use of selective kinase inhibitors an attractive treatment possibility in AD. When sequentially treated with retinoic acid (RA) and brain-derived neurotrophic factor (BDNF), the human neuroblastoma SH-SY5Y differentiates to neuron-like cells. We found that coincident with morphologically evident neurite outgrowth, both the content and phosphorylation state of tau increased in RA-BDNF differentiated SH-SY5Y cells. Tau phosphorylation increased at all the examined sites ser-199, ser-202, thr-205, ser-396, and ser-404, all of which are hyperphosphorylated in AD brain. We also investigated whether GSK3beta, Cdk5 or JNK was involved in tau phosphorylation in the differentiated SH-SY5Y cells. We found that GSK3beta contributed most and that Cdk5 made a minor contribution. JNK was not involved in tau phosphorylation in this system. The GSK3beta-inhibitor, lithium, inhibited tau phosphorylation in a concentration-dependent manner and with good reproducibility, which enables ranking of substances in this cell model. RA-BDNF differentiated SH-SY5Y cells could serve as a suitable model for studying the mechanisms of tau phosphorylation and for screening potential GSK3beta inhibitors.     

Translocation and phosphorylation of calcyclin binding protein during retinoic acid-induced neuronal differentiation of neuroblastoma SH-SY5Y cells

For better understanding of functions of the Calcyclin Binding Protein (CacyBP) and exploring its possible roles in neuronal differentiation, the subcellular localization of human CacyBP was examined in retinoic acid(RA)-induced and uninduced neuroblastoma SH-SY5Y cells. Immunostaining indicated that CacyBP was present in the cytoplasm of uninduced SH-SY5Y cells, in which the resting Ca(2+) concentration was relatively lower than that of RA-induced cells. After the RA induction, immunostaining was seen in both the nucleus and cytoplasm. In the RA-induced differentiated SH-SY5Y cells, CacyBP was phosphorylated on serine residue(s), while it existed in a dephosphorylated form in normal (uninduced) cells. Thus, the phosphorylation of CacyBP occurs when it is translocated to the nuclear region. The translocation of CacyBP during the RA-induced differentiation of SH-SY5Y cells suggested that this protein might play a role in neuronal differentiation.     

Differential effects of α-tocopherol and N-acetyl-cysteine on advanced glycation end product-induced oxidative damage and neurite degeneration in SH-SY5Y cells

Advanced glycation end products (AGEs) result from non-enzymatic glycation of proteins and cause cellular oxidative stress in a nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-dependent manner. Due to these effects, AGEs are implicated as a causal factor in diabetic complications. Several antioxidants, including vitamin E, improve cell viability and diminish markers of oxidative damage in cells exposed to AGEs. However, vitamin E has been studied in cell culture systems with primary focus on apoptosis and lipid peroxidation, while its influences on AGE-induced protein and DNA oxidation, intracellular antioxidant status and cell morphology remain largely unknown. Here, we verify the suppression of AGE-induced cell death and lipid peroxidation by 200μM α-tocopherol in SH-SY5Y cells. We report the partial inhibition of DNA oxidation and a decrease in protein carbonyl formation by α-tocopherol with no effects on intracellular GSH concentrations. We observed that 2mM N-acetyl cysteine (NAC) also had a suppressive effect on DNA and protein oxidation, but unlike α-tocopherol, it caused a marked increase in intracellular GSH. Finally, we compared the ability of both antioxidants to maintain neurites in SH-SY5Y cells and found that α-tocopherol had no effect on neurite loss due to AGEs, while NAC fully maintained cell morphology. Thus, while α-tocopherol suppressed AGE-induced macromolecule damage, it was ineffective against neurite degeneration. These results may implicate thiol oxidation and maintenance as a major regulator of neurite degeneration in this model.     

Vasoactive intestinal peptide-induced neurite remodeling in human neuroblastoma SH-SY5Y cells implicates the Cdc42 GTPase and is independent of Ras-ERK pathway

Vasoactive intestinal peptide (VIP) is known to regulate proliferation or differentiation in normal and tumoral cells. SH-SY5Y is a differentiated cell subclone derived from the SK-N-SH human neuroblastoma cell line and possess all the components for an autocrine action of VIP. In the present study, we investigated the morphological changes and intracellular signaling pathways occurring upon VIP treatment of SH-SY5Y cells. VIP induced an early remodeling of cell projections: a branched neurite network spread out and prominent varicosities developed along neurites. Although activated by VIP, the Ras/ERK pathway was not required for the remodeling process. In contrast, pull-down experiments revealed a strong Cdc42 activation by VIP while expression of a dominant-negative Cdc42 prevented the VIP-induced neurite changes, suggesting an important role for this small GTPase in the process. These data provide the first evidence for a regulation of the activity of Rho family GTPases by VIP and bring new insights in the signaling pathways implicated in neurite remodeling process induced by VIP in neuroblastoma cells.     

The Impact of Differentiation on Cytotoxicity and Insulin Sensitivity in Streptozotocin Treated SH-SY5Y Cells

Recently neuronal insulin resistance was suggested playing a role in Alzheimer’s disease. Streptozotocin (STZ) is commonly used to induce impairment in insulin metabolism. In our previous work on undifferentiated SH-SY5Y cells the compound exerted cytotoxicity without altering insulin sensitivity. Nevertheless, differentiation of the cells to a more mature neuron-like phenotype may considerably affect the significance of insulin signaling and its sensitivity to STZ. We aimed at studying the influence of STZ treatment on insulin signaling in SH-SY5Y cells differentiated by retinoic acid (RA). Cytotoxicity of STZ or low serum (LS) condition and protective effect of insulin were compared in RA differentiated SH-SY5Y cells. The effect of insulin and an incretin analogue, exendin-4 on insulin signaling was also examined by assessing glycogen synthase kinase-3 (GSK-3) phosphorylation. STZ was found less cytotoxic in the differentiated cells compared to our previous results in undifferentiated SH-SY5Y cells. The cytoprotective concentration of insulin was similar in the STZ and LS groups. However, the right-shifted concentration–response curve of insulin induced GSK-3 phosphorylation in STZ-treated differentiated cells is suggestive of the development of insulin resistance that was further confirmed by the insulin potentiating effect of exendin-4. Differentiation reduced the sensitivity of SH-SY5Y cells for the non-specific cytotoxicity of STZ and enhanced the relative significance of development of insulin resistance. The differentiated cells thus serve as a better model for studying the role of insulin signaling in neuronal survival. However, direct cytotoxicity of STZ also contributes to the cell death.

     

Differential effects of α-tocopherol and N-acetyl-cysteine on advanced glycation end product-induced oxidative damage and neurite degeneration in SH-SY5Y cells

Advanced glycation end products (AGEs) result from non-enzymatic glycation of proteins and cause cellular oxidative stress in a nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-dependent manner. Due to these effects, AGEs are implicated as a causal factor in diabetic complications. Several antioxidants, including vitamin E, improve cell viability and diminish markers of oxidative damage in cells exposed to AGEs. However, vitamin E has been studied in cell culture systems with primary focus on apoptosis and lipid peroxidation, while its influences on AGE-induced protein and DNA oxidation, intracellular antioxidant status and cell morphology remain largely unknown. Here, we verify the suppression of AGE-induced cell death and lipid peroxidation by 200 μM α-tocopherol in SH-SY5Y cells. We report the partial inhibition of DNA oxidation and a decrease in protein carbonyl formation by α-tocopherol with no effects on intracellular GSH concentrations. We observed that 2 mM N-acetyl cysteine (NAC) also had a suppressive effect on DNA and protein oxidation, but unlike α-tocopherol, it caused a marked increase in intracellular GSH. Finally, we compared the ability of both antioxidants to maintain neurites in SH-SY5Y cells and found that α-tocopherol had no effect on neurite loss due to AGEs, while NAC fully maintained cell morphology. Thus, while α-tocopherol suppressed AGE-induced macromolecule damage, it was ineffective against neurite degeneration. These results may implicate thiol oxidation and maintenance as a major regulator of neurite degeneration in this model.     

A mutant alphaII-spectrin designed to resist calpain and caspase cleavage questions the functional importance of this process in vivo

alpha- and beta-spectrins are components of molecular scaffolds located under the lipid bilayer and named membrane skeletons. Disruption of these scaffolds through mutations in spectrins demonstrated that they are involved in the membrane localization or the maintenance of proteins associated with them. The ubiquitous alphaII-spectrin chain bears in its central region a unique domain that is sensitive to several proteases such as calpains or caspases. The conservation of this region in vertebrates suggests that the proteolysis of alphaII-spectrin by these enzymes could be involved in important functions. To assess the role of alphaII-spectrin cleavage in vivo, we generated a murine model in which the exons encoding the region defining this cleavage sensitivity were disrupted by gene targeting. Surprisingly, homozygous mice expressing this mutant alphaII-spectrin appeared healthy, bred normally, and had no histological anomaly. Remarkably, the mutant alphaII-spectrin assembles correctly into the membrane skeleton, thus challenging the notion that this region is required for the stable biogenesis of the membrane skeleton in nonerythroid cells. Our finding also argues against a critical role of this particular alphaII-spectrin cleavage in either major cellular functions or in normal development.     

Mitochondrial localization of mu-calpain

Calcium-dependent cysteine proteases, calpains, have physiological roles in cell motility and differentiation but also play a pathological role following insult or disease. The ubiquitous calpains are widely considered to be cytosolic enzymes, although there has been speculation of a mitochondrial calpain. Within a highly enriched fraction of mitochondria obtained from rat cortex and SH-SY5Y human neuroblastoma cells, immunoblotting demonstrated enrichment of the 80kDa mu-calpain large subunit and 28kDa small subunit. In rat cortex, antibodies against domains II and III of the large mu-calpain subunit also detected a 40kDa fragment, similar to the autolytic fragment generated following incubation of human erythrocyte mu-calpain with Ca(2+). Mitochondrial proteins including apoptosis inducing factor and mitochondrial Bax are calpain substrates, but the mechanism by which calpains gain access to these proteins is uncertain. Mitochondrial localization of mu-calpain places the enzyme in proximity to its mitochondrial substrates and to Ca(2+) released from mitochondrial stores.     

Participation of type II protein kinase A in the retinoic acid-induced growth inhibition of SH-SY5Y human neuroblastoma cells

To examine the role of protein kinase A (EC 2.7.1.37) isozymes in the retinoic acid-induced growth inhibition and neuronal differentiation, we investigated the changes of protein kinase A isozyme patterns in retinoic acid-treated SH-SY5Y human neuroblastoma cells. Retinoic acid induced growth inhibition and neuronal differentiation of SH-SY5Y cells in a dose- and time-dependent manner. Neuronal differentiation was evidenced by extensive neurite outgrowth, decrease of N-Myc oncoprotein, and increase of GAP-43 mRNA. Type II protein kinase A activity increased by 1.5-fold in differentiated SH-SY5Y cells by retinoic acid treatment. The increase of type II protein kinase A was due to the increase of RIIbeta and Calpha subunits. Since type II protein kinase A and RIIbeta have been known to play important role(s) in the growth inhibition and differentiation of cancer cells, we further investigated the role of the increased type II protein kinase A by overexpressing RIIbeta in SH-SY5Y cells. The growth of RIIbeta-overexpressing cells was slower than that of parental cells, being comparable to that of retinoic acid-treated cells. Retinoic acid treatment further increased the RIIbeta level and further inhibited the growth of RIIbeta-overexpressing cells, showing strong correlation between the level of RIIbeta and growth inhibition. However, RIIbeta-overexpressing cells did not show any sign of neuronal differentiation and responded to retinoic acid in the same way as parental cells. These data suggest that protein kinase A participates in the retinoic acid-induced growth inhibition through the up-regulation of RIIbeta/type II protein kinase A.     

Activation of Rac1 by phosphatidylinositol 3-kinase in vivo: role in activation of mitogen-activated protein kinase (MAPK) pathways and retinoic acid-induced neuronal differentiation of SH-SY5Y cells

Rho GTPases such as RhoA, Rac1 and Cdc42 are crucial players in the regulation of signal transduction pathways required for neuronal differentiation. Using an in vitro cell culture model of neuroblastoma SH-SY5Y cells, we demonstrated previously that RhoA is an in vivo substrate of tissue transglutaminase (TGase) and retinoic acid (RA) promoted activation of RhoA by transamidation. Although activation of RhoA promoted cytoskeletal rearrangement in SH-SY5Y cells, it was not involved in induction of neurite outgrowth. Here, we demonstrate that RA promotes activation of Rac1 in SH-SY5Y cells in a transamidation-independent manner. RA-induced activation of Rac1 is mediated by phosphatidylinositol 3-kinase (PI3K), probably because of phosphorylation of the p85 regulatory subunit by Src kinases. Over-expression of constitutively active PI3K or Rac1-V12 induces neurite outgrowth, activation of mitogen activated protein kinases (MAPKs), and expression of neuronal markers. The PI3K inhibitor LY294002, or over-expression of dominant negative Rac1-N17, blocks RA-induced neurite outgrowth, activation of MAPKs, and expression of neuronal markers, suggesting that activation of PI3K/Rac1 signaling represents a potential mechanism for regulation of neuronal differentiation in SH-SY5Y cells.     

Beclin-1 shRNA对低氧诱导的SH-SY5Y细胞自噬的影响

目的：构建Beclin-1基因短发夹干扰RNA（shRNA）慢病毒载体,感染人SH-SY5Y细胞,观察沉默Beclin-1基因后低氧对SH-SY5Y细胞自噬的影响。方法：构建特异性靶向Beclin-1基因的shRNA慢病毒表达载体和阴性对照序列慢病毒载体;再将载体转染入SH-SY5Y细胞;RT-PCR检测Beclin-1的mRNA表达;Western blot检测Beclin-1蛋白表达;CCK-8法测定Beclin-1 shRNA对SH-SY5Y细胞活力的影响。再将空白对照、阴性对照、转染型三种细胞分别以21%常氧及5%低氧培养,Western blot检测各组细胞LC3蛋白表达;电镜观察自噬小体。结果：Beclin-1 shRNA能明显抑制SH-SY5Y细胞Beclin-1的mRNA及蛋白的表达;沉默Beclin-1基因后,Beclin-1 shRNA组细胞存活率与阴性对照组相比无差异;成功建立了稳定表达Beclin-1 shRNA的SH-SY5Y细胞。5%低氧处理后,与阴性对照组相比较,Beclin-1 shRNA组细胞中LC3Ⅱ/LC3Ⅰ比值下调,细胞内自噬小体数量减少。结论：慢病毒介导的Beclin-1shRNA对SH-SY5Y细胞的活力无影响,但可以抑制低氧诱导的自噬。