Melittin induces human gastric cancer cell apoptosis via activation of mitochondrial pathway

AIM: To investigate the apoptotic effects of melittin on SGC-7901 cells via activation of the mitochondrial signaling pathway in vitro.METHODS: SGC-7901 cells were stimulated by melittin, and its effect on proliferation and apoptosis of was investigated by methyl thiazolyl tetrazolium assay, morphologic structure with transmission electron microscopy, annexin-V/propidium iodide double-staining assay, measuring mitochondrial membrane potential(MMP) levels, and analyzing reactive oxygen species(ROS) concentrations were analyzed by flow cytometry. Cytochrome C(Cyt C), apoptosis-inducing factor(AIF), endonuclease G(Endo G), second mitochondria-derived activator of caspases(Smac)/direct IAP binding protein with low isoelectric point(Diablo), and FAS were analyzed by western blot. The expression of caspase-3 and caspase-8 was measured using activity assay kits.RESULTS: Melittin was incubated at 1.0, 2.0, 4.0, or 6.0 μg/m L for 1, 2, 4, 6, or 8 h and showed a timeand concentration-dependent inhibition of SGC-7901 cell growth. Melittin induced SGC-7901 cell apoptosis, which was confirmed by typical morphological changes. Treatment with 4 μg/m L melittin induced early apoptosis of SGC-7901 cells, and the early apoptosis rates were 39.97% ± 3.19%, 59.27% ± 3.94%, and 71.50% ± 2.87% vs 32.63% ± 2.75% for 1, 2, and 4 h vs 0 h(n = 3, P 0.05); the ROS levels were 616.53% ± 79.78%, 974.81% ± 102.40%, and 1330.94% ± 93.09% vs 603.74% ± 71.99%(n = 3, P 0.05); the MMP values were 2.07 ± 0.05, 1.78 ± 0.29, and 1.16 ± 0.25 vs 2.55 ± 0.42(n = 3, P 0.05); caspase-3 activity was significantly higher compared to the control(5492.3 ± 321.1, 6562.0 ± 381.3, and 8695.7 ± 449.1 vs 2330.0 ± 121.9), but the caspase activity of the non-tumor cell line L-O2 was not different from that of the control. With the addition of the caspase-3 inhibitor(Ac-DEVD-CHO), caspase-3 activity was significantly decreased compared to the control group(1067.0 ± 132.5 U/g vs 8695.7 ± 449.1 U/g). The expression of the Cyt C, Endo G, and AIF proteins in SGC-7901 cells was significantly higher than those in the control(P 0.05), while the expression of the Smac/Diablo protein was significantly lower than the control group after melittin exposure(P 0.01). Ac-DEVD-CHO did not, however, have any effect on the expression of caspase-8 and FAS in the SGC-7901 cells.CONCLUSION: Melittin can induce apoptosis of human gastric cancer(GC) cells through the mitochondria pathways, and it may be a potent agent in the treatment of human GC.     

Silybin counteracts lipid excess and oxidative stress in cultured steatotic hepatic cells

AIM: To investigate in vitro the therapeutic effect and mechanisms of silybin in a cellular model of hepatic steatosis.METHODS: Rat hepatoma Fa O cells were loaded with lipids by exposure to 0.75 mmol/L oleate/palmitate for 3 h to mimic liver steatosis. Then, the steatotic cells were incubated for 24 h with different concentrations(25 to 100 μmol/L) of silybin as phytosome complex with vitamin E. The effects of silybin on lipid accumulation and metabolism, and on indices of oxidative stress were evaluated by absorption and fluorescence microscopy, quantitative real-time PCR, Western blot, spectrophotometric and fluorimetric assays.RESULTS: Lipid-loading resulted in intracellular triglyceride(TG) accumulation inside lipid droplets, whose number and size increased. TG accumulation was mediated by increased levels of peroxisome proliferator-activated receptors(PPARs) and sterol regulatory element-binding protein-1c(SREBP-1c). The lipid imbalance was associated with higher production of reactive oxygen species(ROS) resulting in increased lipid peroxidation, stimulation of catalase activity and activation of nuclear factor kappa-B(NF-κB). Incubation of steatotic cells with silybin 50 μmol/L significantly reduced TG accumulation likely by promoting lipid catabolism and by inhibiting lipogenic pathways, as suggested by the changes in carnitine palmitoyltransferase 1(CPT-1), PPAR and SREBP-1c levels. The reduction in fat accumulation exerted by silybin in the steatotic cells was associated with the improvement of the oxidative imbalance caused by lipid excess as demonstrated by the reduction in ROS content, lipid peroxidation, catalase activity and NF-κB activation.CONCLUSION: We demonstrated the direct antisteatotic and anti-oxidant effects of silybin in steatotic cells, thus elucidating at a cellular level the encouraging results demonstrated in clinical and animal studies.     

Barth综合征导致幼儿心内膜弹力纤维增生症的临床特点及其<i>TAZ</i>基因突变

目的探讨以心内膜弹力纤维增生症为主要表现的Barth综合征患儿的临床表现、诊断、治疗及TAZ基因突变情况。 方法选择2014年11月因"间断咳喘、发现心内膜弹力纤维增生症1个月",于北京大学第一医院住院治疗的1例1岁7个月男性Barth综合征患儿为研究对象。对患儿进行血常规、生化(心肌酶谱等)、心血管功能检查,尿液有机酸谱分析、血液氨基酸及酯酰肉碱谱测定,检测患儿及其父母的基因突变情况。 结果①相关检测结果：本例患儿智力正常,体格及运动发育落后,肌张力低。血常规检测结果显示中性粒细胞减少及其百分率降低。超声心动图等结果显示左心室肥大,心肌肥厚,心功能不全。尿液3-甲基戊烯二酸显著增高,为241.34 mmol/mol肌酐(正常参考值为0～4.2 mmol/mol肌酐,均值为1.1 mmol/mol肌酐),为正常均值的219.4倍。血液氨基酸谱正常,血浆游离肉碱浓度降低,为13 μmol/L(正常参考值为20～60 μmol/L)。基因检测结果显示,患儿存在TAZ基因c.280 C>T(p.R94C)突变,母亲为TAZ基因c.280 C>T杂合突变携带者。②临床治疗及预后：对本例患儿采取口服左卡尼汀、维生素B1、辅酶Q10、地高辛、酒石酸美托洛尔片等治疗后,患儿体力好转,尿液3-甲基戊烯二酸水平降至正常,心功能恢复正常。 结论Barth综合征为X连锁遗传性线粒体病,是导致心肌病的重要原因之一。尿液有机酸谱分析及TAZ基因检测,有助于该病的临床诊断及治疗。     

Roles of two types of anion channels in glutamate release from mouse astrocytes under ischemic or osmotic stress

Astrocytes release glutamate upon hyperexcitation in the normal brain, and in response to pathologic insults such as ischemia and trauma. In our experiments, both hypotonic and ischemic stimuli caused the release of glutamate from cultured mouse astrocytes, which occurred with little or no contribution of gap junction hemichannels, vesicle-mediated exocytosis, or reversed operation of the Na-dependent glutamate transporter. Cell swelling and chemical ischemia activated, in cell-attached membrane patches, anionic channels with large unitary conductance (approximately 400 pS) and inactivation kinetics at potentials more positive than +20 mV or more negative than -20 mV. These properties are different from those of volume-sensitive outwardly rectifying (VSOR) Cl- channels, which were also expressed in these cells and exhibited intermediate unitary conductance (approximately 80 pS) and inactivation kinetics at large positive potentials of more than +40 mV. Both maxi-anion channels and VSOR Cl- channels were permeable to glutamate with permeability ratios of glutamate to chloride of 0.21 +/- 0.07 and 0.15 +/- 0.01, respectively. However, the release of glutamate was significantly more sensitive to Gd3+, a blocker of maxi-anion channels, than to phloretin, a blocker of VSOR Cl- channels. We conclude that these two channels jointly represent a major conductive pathway for the release of glutamate from swollen and ischemia-challenged astrocytes, with the contribution of maxi-anion channels being predominant.     

A scale to monitor progression and treatment of mitochondrial disease in children

Mitochondrial diseases affect all age groups, but those with childhood onset often seem to experience the greatest burden of disability. In some paediatric patients this can be explained by a cumulative disability acquired over many years. In others, additional factors, including the nature and severity of the molecular defect, must be considered. To date, no large-scale studies have attempted to document the natural history of paediatric mitochondrial disease. This is in part at least, because no assessment tool has been available to plot the temporal course of a disease with such a diverse clinical spectrum. This paper describes how a practical and semi-quantitative rating scale has been devised for children with mitochondrial disease, the Newcastle paediatric mitochondrial disease scale (NPMDS). The scale is multi-dimensional and reproducible, offering a tool through which mitochondrial disease progression can be objectively monitored. We anticipate that use of this tool will facilitate both longitudinal natural history studies and the assessment of future therapeutic interventions.     

Neurodegeneration induced by complex I inhibition in a cellular model of familial amyotrophic lateral sclerosis

G93A Cu/Zn superoxide dismutase (SOD1), a human mutant SOD1 associated with familial amyotrophic lateral sclerosis, increased the toxicity of the mitochondrial toxin rotenone in the NSC-34 motoneuronal cell line. G93ASOD1 cells died more than untransfected and wild-type SOD1 cells after 6 and 24h exposure to 12.5 microM rotenone. Biparametric flow cytometry showed that rotenone induced rapid hyperpolarization of mitochondrial membrane potential (deltapsi(m)) in all the cell lines, followed by depolarization, and then by cell death. However, G93ASOD1 mitochondria were significantly more likely to shift from a hyperpolarized to a depolarized condition, and within the still viable cell population there was a higher proportion with depolarized mitochondria, a condition that can be envisaged as a commitment to cell death. ATP, which is needed to prevent loss of deltapsi(m), decreased more rapidly and to a greater extent in rotenone-treated G93ASOD1 cells than in the untransfected and wtSOD1cells. In all the cell lines, 1h after rotenone exposure, mitochondrial hyperpolarization was accompanied by the formation of a comparable amount of reactive oxygen species. However, G93ASOD1 cells reached the highest reactive oxygen species level since their basal level was higher than in untransfected and wild-type SOD1 cells. Our findings indicate that the mutant protein G93ASOD1 enhances the vulnerability of motor neurons to rotenone by mechanism(s) involving oxidative stress and perturbed mitochondrial homeostasis. This suggests that motor neurons from individuals carrying the mutant G93ASOD1 are at greater risk of death after inhibition of the electron transport chain.     

窒息新生鼠心肌线粒体膜通透性转换孔开放度的变化

目的 观察新生鼠窒息后心肌组织缺血损伤情况以及心肌细胞线粒体膜通透性转换孔(mitochondrial permeability transition pore,MPTP)开放度的变化,以期揭示MPTP开放在窒息后心肌缺氧缺血及再灌注损伤的作用机制.方法 成年SD母鼠妊娠第21天行剖宫产,随机分为正常分娩组及动脉夹闭组,正常分娩组不夹闭子宫动脉,所分娩新生鼠为对照组;以夹闭动脉夹闭组孕鼠子宫动脉方法制作宫内窒息新生大鼠模型,为窒息组,每组各30只,于出生24 h处死新生鼠.以ELISA法检测血清心肌肌钙蛋白Ⅰ(cardiac troponin Ⅰ,cTn Ⅰ),以荧光分光光度法检测MPTP开放度;以TTC染色法检测心肌缺血面积;以HE染色法观察心肌细胞形态变化.结果 HE染色观察发现,窒息组心肌细胞排列紊乱、细胞肿胀、部分细胞溶解.对照组、窒息组新生鼠血清cTn Ⅰ分别为(0.08 ±0.04) μg/L、(0.40±0.29) μg/L,窒息组明显升高,差异有统计学意义(P＜0.01).对照组、窒息组新生鼠TTC染色心肌缺血面积分别为(8.01±3.48)％、(42.50±15.90)％(P ＜0.01).窒息组出现心肌点状坏死,缺血面积增大.对照组、窒息组新生鼠MPTP相对荧光单位分别为118.10±19.10、79.40±10.57 (P＜0.01),窒息组心肌MPTP开放度增大.各组新生大鼠血清cTn Ⅰ值与MPTP开放度呈正相关(r=-0.384,P＜0.01).结论 窒息新生大鼠出现心肌损伤,表现为血清cTn Ⅰ升高、心肌缺血及坏死.窒息后心肌MPTP开放度增大是导致心肌损伤的重要原因.     

Investigation of mtDNA control region sequences in an Egyptian population sample

The sequences of mitochondrial DNA (mtDNA) control region were investigated in 101 unrelated individuals living in the northern region of Nile delta (Gharbia, N = 55 and Kafrelsheikh, N = 46). DNA was extracted from blood stained filter papers or buccal swabs. HV1, HV2 and HV3 were PCR amplified and sequenced; the resulted sequences were aligned and compared with revised Cambridge sequence (rCRS). The results revealed presence of total 93 different haplotypes, 86 of them are unique and 7 are shared haplotypes, the most common haplotype, was observed with a frequency, 2.97% of population sample. High mtDNA diversity was observed with genetic diversity and power of discrimination, 0.9982 and 0.9883, respectively. In this dataset the west Eurasian haplogroups predominated over the African haplogroups. The results would be useful for forensic examinations and human genetic studies.     

L-Threonine induces heat shock protein expression and decreases apoptosis in heat-stressed intestinal epithelial cells

ObjectivesOsmotically acting amino acids can be cytoprotective following injury. As threonine (THR) induces osmotic cell swelling, our aim was to investigate the potential for THR to induce cellular protection in intestinal epithelial cells and evaluate possible mechanisms of protection.MethodsCells treated with a range of THR doses were evaluated following heat stress (HS) injury. Alpha-aminoisobutyric acid (AIB), a non-metabolizable amino acid analog, was used as an osmotic control. MTS assays were used to assess cell survival. Heat shock protein (HSP) expression and cleaved caspase-3 (CC3) were evaluated via Western blot. Cell morphology and cell size were analyzed via microscopy.ResultFollowing HS, THR treatment increased cell viability in a dose dependent manner vs. non-THR treated cells (CT). The non-metabolized amino acid analogue, AIB, also increased cell survival in heat-stressed cells versus HS controls. HSP70 and HSP25 expression increased with THR and AIB treatment versus HS controls. THR also increased HSP25 in non-stressed cells. Microscopic evaluation revealed both THR and AIB preserved the structural integrity of the actin cytoskeleton in heat-stressed cells versus HS controls. THR, but not AIB, enhanced nuclear translocation of HSP25 during HS. This nuclear translocation was associated with a 60% decrease in apoptosis in heat-stressed cells with THR. No antiapoptotic effect was observed with AIB.ConclusionsThis is the first demonstration that THR increases HSP70 and HSP 25 and protects cells from HS. THR's mechanism of protection may involve cytoskeletal stabilization, HSP up-regulation and nuclear translocation, and decreased apoptosis. THR's protection appears to involve both cell-swelling–dependent and –independent processes.