Glutaminase1 heterozygous mice show enhanced trace fear conditioning and Arc/Arg3.1 expression in hippocampus and cingulate cortex

Mice heterozygous for a mutation in the glutaminase (GLS1) gene (GLS1 HZ mice), with reduced glutamate recycling and release, display reduced hippocampal function as well as memory of contextual cues in a delay fear conditioning (FC) paradigm. Here, we asked whether this deficit reflects an inability to process contextual information or a selective alteration in salience attribution. In addition, we asked whether baseline and activity-induced hippocampal activity were diminished in GLS1 HZ mice. For this purpose, we manipulated the relative salience of the conditioned stimulus (CS) and contextual cues in FC tasks, and examined gene expression of the immediate early gene Arc (Arc/Arg3.1) in hippocampus and anterior cingulate cortex (ACC) following trace FC (tFC). The results indicate that GLS1 HZ mice succeed in processing contextual information when the salient CS is absent or less predictive. In addition, in the hippocampus-dependent tFC paradigm GLS1 HZ mice display enhanced CS learning. Furthermore, while baseline arc activation was reduced in GLS1 HZ mice in the hippocampus, in line with previous fMRI findings, it was enhanced in the hippocampus and anterior cingulate cortex following tFC. These findings suggest that GLS1 HZ mice have a pro-cognitive profile in the tFC paradigm, and this phenotype involves activation of both hippocampus and ACC.Taken together with previous work on the GLS1 HZ mouse, this study sheds light on the importance of glutamate transmission to memory processes that require the allocation of attentional resources, and extends our understanding of the underpinnings of attention deficits in SZ.     

结直肠癌患者组织中HIF-1α和GLS2表达水平与病理程度和预后的相关性

目的探讨结直肠癌组织中缺氧诱导因子-1α(HIF-1α)和2型谷氨酰胺酶(GLS2)表达水平与患者病理及预后的相关性。方法选取2015年3月至2016年3月行手术切除的结直肠癌组织89例,癌旁组织67例(距肿瘤5 cm以上),用免疫组织化学方法检测HIF-1α和GLS2的表达。应用SPSS 19.0统计学软件分析,HIF-1α和GLS2表达水平及与结直肠癌病理因素的关系采用卡方检验,患者预后的影响因素采用COX回归模型,以P0.05表示差异有统计学意义。结果结直肠癌组织中HIF-1α的阳性率为64.0%(57例),GLS2的阳性率为67.4%(60例),明显高于癌旁组织(13.4%、19.4%),差异有统计学意义(P0.05);结直肠癌组织中HIF-1α和GLS2的阳性率与肿瘤分期、分化程度和淋巴结转移有关;肿瘤分期为Ⅲ/Ⅳ期、分化程度差和淋巴结转移的结直肠癌组织中的HIF-1α和GLS2的阳性率显著高于肿瘤分期为Ⅰ/Ⅱ期、分化程度好和淋巴结未转移的结直肠癌组织(P0.05);COX回归模型得出结直肠癌患者的HIF-1α、GLS2、肿瘤分期、分化程度和淋巴结转移均是患者预后的影响因素(P0.05)。结论 HIF-1α和GLS2在结直肠癌组织中高表达、提示预后不良,与结直肠癌的发生、发展存在相关性,有望成为结直肠癌评估诊断的新靶点。     

Subacute nicotine exposure in cultured cerebellar cells increased the release and uptake of glutamate

Cerebellar granule and glial cells prepared from 7 day-old rat pups were used to investigate the effects of sub-acute nicotine exposure on the glutamatergic nervous system. These cells were exposed to nicotine in various concentrations for 2 to 10 days in situ. Nicotine-exposure did not result in any changes in cerebellar granule and glial cell viability at concentrations of up to 500 microM. In cerebellar granule cells, the basal extracellular levels of glutamate, aspartate and glycine were enhanced in the nicotine-exposed granule cells. In addition, the responses of N-methyl-D-aspartate (NMDA)-induced glutamate release were enhanced at low NMDA concentrations in the nicotine-exposed granule cells. However, this decreased at higher NMDA concentrations. The glutaminase activity was increased after nicotine exposure. In cerebellar glial cells, glutamate uptake in the nicotine-exposed glial cells were either increased at low nicotine exposure levels or decreased at higher levels. The inhibition of glutamate uptake by L-trans-pyrollidine-2,4-dicarboxylic acid (PDC) was lower in glial cells exposed to 50 microM nicotine. Glutamine synthetase activity was lower in glial cells exposed to 100 or 500 microM of nicotine. These results indicate that the properties of cerebellar granule and glial cells may alter after subacute nicotine exposure. Furthermore, they suggest that nicotine exposure during development may modulate glutamatergic nervous activity.     

GA反义基因对裸鼠胃癌移植瘤细胞凋亡的影响

目的研究反义核酸技术封闭谷氨酰胺酶（GA）基因对裸鼠体内胃癌细胞凋亡作用的影响。方法将携带GA反义基因的质粒转染胃癌细胞SGC-7901，并将成功转染的胃癌细胞接种于裸鼠皮下，获得裸鼠胃癌移植瘤模型，通过TUNEL技术检测胃癌细胞凋亡的凋亡指数；RT-PCR技术检测移植瘤细胞内GAmRNA的含量。结果GA反义基因质粒载体成功转染胃癌细胞后，肿瘤生长速度减慢，癌细胞凋亡增加，肿瘤细胞内GAmRNA的含量减少。结论GA反义基因可抑制GA基因的表达，明显促进胃癌细胞凋亡。     

谷氨酰胺代谢对卵巢肿瘤细胞生物学行为的影响

谷氨酰胺是可以由细胞自身合成的非必需氨基酸,对体外培养的哺乳动物细胞生长和增殖具有非常重要的意义。在肿瘤细胞增殖过程中谷氨酰胺不仅满足了蛋白质合成的需要,也是嘌呤和嘧啶合成过程中氮元素的主要供体。研究显示谷氨酰胺成瘾的肿瘤细胞依赖谷氨酰胺生存,并通过三羧酸循环对谷氨酰胺利用进行重编程。阻断高侵袭性卵巢癌细胞中谷氨酰胺进入三羧酸循环,或抑制低侵袭性卵巢癌细胞谷氨酰胺合成,可能是卵巢癌潜在的治疗方法。谷氨酰胺代谢与卵巢癌不良预后有关;抑制谷氨酰胺代谢通路和以铂类为基础的联合使用,可能是卵巢癌治疗的新策略,特别是耐药性卵巢癌。综述谷氨酰胺代谢在卵巢癌细胞增殖、侵袭和药物抵抗等生物学行为方面的作用,探讨其作为潜在的卵巢癌诊断、治疗和预后的新靶点或生物标记。     

Development of Escherichia coli asparaginase II for the Treatment of Acute Lymphocytic Leukemia: In Silico Reduction of asparaginase II Side Effects by a Novel Mutant (V27F)

Acute lymphoblastic leukemia (ALL) is a common blood disease in children that is accountable for many deaths. Due to major improvements in treatment procedures in the past 50 years, the survivability of this disease has risen dramatically to about 90 percent today. L-asparaginase (ASNase) has been used to treat ALL. The glutaminase (GLNase) activity of this enzyme causes some side effects and is unnecessary for anticancer activity. This study investigated mutagenesis in Escherichia coli ASNase II to find a mutant with lower GLNase activity via molecular dynamics (MD) simulation. Residues with low binding energy to asparagine (Asn) and high binding energy to glutamine (Gln) were chosen for mutagenesis. A mutant with low free binding energy to Gln was then selected for molecular docking and MD studies. The results showed that V27F is a good candidate for reducing GLNase activity and that it has little effect on enzyme ASNase activity. A simulation analysis showed that the V27F mutant was more stable than the WT ASNase and that mutagenesis was quite successful.     

大鼠谷氨酰胺酶反义真核表达载体的构建及鉴定

目的 :构建大鼠谷氨酰胺酶 (GA)反义真核表达载体。　方法 :采用分子克隆技术将rGAcDNA反向克隆到真核表达载体pcDNA 3.0中。　结果 :EcoRⅠ和HinDⅢ双酶切后 ,反义重组基因为 0 .2 8kb和 5 .4kb两条带 ,与理论计算相符。　结论 :成功构建了大鼠GA反义真核表达载体 ,为肿瘤细胞的GA反义基因治疗研究创造条件     

Altered Glutamine Metabolism and Therapeutic Opportunities for Lung Cancer

Disordered cancer metabolism was described almost a century ago as an abnormal adaptation of cancer cells to glucose utilization especially in hypoxic conditions; the so-called Warburg effect. Greater research interest in this area in the past two decades has led to the recognition of the critical coupling of specific malignant phenotypes such as increased proliferation and resistance to programmed cell death (apoptosis) with altered metabolic handling of key molecules that are essential for normal cellular metabolism. The altered glucose metabolism frequently encountered in cancer cells has already been exploited for cancer diagnosis and treatment. The role of other glycolytic pathway intermediates and alternative pathways for energy generation and macromolecular synthesis in cancer cells has only become recognized more recently. Especially, the important role of altered glutamine metabolism in the malignant behavior of cancer cells and the potential exploitation of this cellular adaptation for therapeutic targeting has now emerged as an important area of cancer research. Expectedly, attempts to exploit this understanding for diagnostic and therapeutic ends are running apace with the elucidation of the complex metabolic alterations that accompany neoplastic transformation. Because lung cancer is a leading cause of cancer death with limited curative therapy options, careful elucidation of the mechanism and consequences of disordered cancer metabolism in lung cancer is warranted. This review provides a concise, systematic overview of the current understanding of the role of altered glutamine metabolism in cancer, and how these findings intersect with current and future approaches to lung cancer management.     

Histochemistry of glutamate metabolizing enzymes in the rat cerebellar cortex

Applying catalytic enzyme histochemistry, glutamate dehydrogenase (GDH) and phosphate activated glutaminase (PAG) were demonstrated at the light microscopic level, and aspartate aminotransferase (AAT) was detected at the electron microscopic level. GDH staining appeared preferentially in glial cells (Bergmann glia and astrocytes), whereas AAT was localized only in neuronal structures. Cytoplasmic AAT was demonstrated in the perikarya and terminal plexus of basket cells, in the perikarya of stellate cells, in about 60% of the granule cells, in mossy fiber boutons, in numerous small boutons in the molecular layer, and in the axoplasm of numerous myelinated and unmyelinated fibers. PAG was observed in both neuronal structures (perikarya of granule and Purkinje cells) and in astrocytes and Bergmann glia.