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Julia Buerger, Nadine Rehm, Laura Grebenstein, Andreas Burkovski
Corynebacterium glutamicum is able to metabolize different nitrogen and carbon sources. In standard minimal media, ammonium and urea typically serve as nitrogen source and glucose or sucrose as carbon and energy source; however, amino acids might also play a role as nitrogen, carbon and energy source. In this study, the function of the putative glutaminase GlsK was investigated. A glsK deletion strain showed impaired growth with L-glutamine as carbon and energy source, while growth was improved upon glsK overexpression...
October 2016: FEMS Microbiology Letters
Jem Ma Ahn, Chang Ha Kim, Soon Ho Um, Kyung Mee Kim, Tae Hyung Kim, Sun Young Yim, Hyuk Soon Choi, Eun Sun Kim, Bora Keum, Yeon Seok Seo, Hyung Joon Yim, Yoon Tae Jeen, Hong Sik Lee, Hoon Jai Chun, Chang Duck Kim, Ho Sang Ryu
BACKGROUND AND AIM: In a recent study, microsatellite variations (GCA tandem repeats) in the promoter region of the (kidney-type) glutaminase gene were associated with the development of hepatic encephalopathy (HE) in Spanish patients with cirrhosis. The objective of this study was to validate the relation between microsatellite variations in the glutaminase promoter region and the development of overt HE in Korean patients with liver cirrhosis. METHODS: We performed a prospective cohort study of 154 cirrhotic patients who underwent a glutaminase microsatellite study without previous overt HE history at baseline...
October 17, 2016: Journal of Gastroenterology and Hepatology
A Cacace, M Sboarina, T Vazeille, P Sonveaux
Cancer cells can use a variety of metabolic substrates to fulfill the bioenergetic and biosynthetic needs of their oncogenic program. Besides bioenergetics, cancer cell metabolism also directly influences genetic, epigenetic and signaling events associated with tumor progression. Many cancer cells are addicted to glutamine, and this addiction is observed in oxidative as well as in glycolytic cells. Although both oxidative and bioreductive glutamine metabolism can contribute to cancer progression and glutamine can further serve to generate peptides (including glutathione) and proteins, we report that glutamine promotes the proliferation of cancer cells independently of its use as a metabolic fuel or as a precursor of glutathione...
October 17, 2016: Oncogene
Tsang-Chih Kuo, Chi-Kuan Chen, Kuo-Ti Hua, Pei Yu, Wei-Jiunn Lee, Min-Wei Chen, Yung-Ming Jeng, Ming-Hsien Chien, Kuang-Tai Kuo, Michael Hsiao, Min-Liang Kuo
Glutaminolysis that catabolizes glutamine to glutamate plays a critical role in cancer progression. Glutaminase 2 (GLS2) has been reported as a tumor suppressor. Recent studies implied that GLS2 may display its multifunction besides classical metabolic feature by different localizations and potential protein binding domains. Here, we showed that GLS2 expression correlates inversely with stage, vascular invasion, tumor size and poor prognosis in human hepatocellular carcinoma (HCC) tissues. We found that GLS2 significantly represses cell migration, invasion and metastasis of HCC through downregulation of Snail in vitro and in vivo...
October 7, 2016: Cancer Letters
Cedric Peleman, Michael Camilleri
Rifaximin is beneficial in the treatment of minimal hepatic encephalopathy (MHE). Kang et al. (Clin Transl Gastroenterol 7: e187; doi:10.1038/ctg.2016.44) investigated the effects of rifaximin in a mouse model of MHE-associated microbiota without concomitant liver disease. In addition to some impact on the composition of microbiota, rifaximin altered bacterial functions, ameliorated local and systemic inflammation, and reduced enterocyte glutaminase activity. We discuss these effects as well as the interpretation of the permeability studies, given the potential interaction of dysbiosis with dysfunctional intestinal barrier, leading to systemic inflammation and increased uptake of bacterial metabolites that contribute to MHE in the presence of hepatic dysfunction...
October 6, 2016: Clinical and Translational Gastroenterology
Sujin Lee, He Wen, Jin Wook Cha, Sunghyouk Park
Glutamine plays key roles as a biosynthetic precursor or an energy source in cancers, and interest in its metabolism is rapidly growing. However, the proper evaluation of glutamine hydrolysis, the very first reaction in the entire glutaminolysis, has been difficult. Here, we report a triple resonance NMR-based assay for specific detection of glutaminase activity carrying out this reaction using stable-isotope labeled glutamine. Compared to conventional methods involving coupled enzyme assays, the proposed approach is direct because it detects the presence of the H-N-CO amide spin system...
October 4, 2016: ACS Chemical Biology
Luisa Baker, Bernard Lanz, Fausto Andreola, Javier Ampuero, Anisha Wijeyesekera, Elaine Holmes, Nicolaas Deutz
Hepatic encephalopathy (HE) is a neuropsychiatric syndrome which frequently accompanies acute or chronic liver disease. It is characterized by a variety of symptoms of different severity such as cognitive deficits and impaired motor functions. Currently, HE is seen as a consequence of a low grade cerebral oedema associated with the formation of cerebral oxidative stress and deranged cerebral oscillatory networks. However, the pathogenesis of HE is still incompletely understood as liver dysfunction triggers exceptionally complex metabolic derangements in the body which need to be investigated by appropriate technologies...
September 30, 2016: Metabolic Brain Disease
Marc Yudkoff
Glutamatergic neurotransmission entails a tonic loss of glutamate from nerve endings into the synapse. Replacement of neuronal glutamate is essential in order to avoid depletion of the internal pool. In brain this occurs primarily via the glutamate-glutamine cycle, which invokes astrocytic synthesis of glutamine and hydrolysis of this amino acid via neuronal phosphate-dependent glutaminase. This cycle maintains constancy of internal pools, but it does not provide a mechanism for inevitable losses of glutamate N from brain...
October 1, 2016: Neurochemical Research
Sanjeev Kumar, Sunita Prakash, Kallol Gupta, Aparna Dongre, Padmanabhan Balaram, Hemalatha Balaram
Protein ageing is often mediated by the formation of succinimide intermediates. These short-lived intermediates derive from asparaginyl deamidation and aspartyl dehydration and are rapidly converted into β-aspartyl or D-aspartyl residues. Here we report the presence of a highly stable succinimide intermediate in the glutaminase subunit of GMP synthetase from the hyperthermophile Methanocaldoccocus jannaschii. By comparing the biophysical properties of the wild-type protein and of several mutants, we show that the presence of succinimide increases the structural stability of the glutaminase subunit...
2016: Nature Communications
Graham C Robinson, Markus Kaufmann, Céline Roux, Teresa B Fitzpatrick
Vitamin B6 is indispensible for all organisms, notably as the coenzyme form pyridoxal 5'-phosphate. Plants make the compound de novo using a relatively simple pathway comprising pyridoxine synthase (PDX1) and pyridoxine glutaminase (PDX2). PDX1 is remarkable given its multifaceted synthetic ability to carry out isomerization, imine formation, ammonia addition, aldol-type condensation, cyclization, and aromatization, all in the absence of coenzymes or recruitment of specialized domains. Two active sites (P1 and P2) facilitate the plethora of reactions, but it is not known how the two are coordinated and, moreover, if intermediates are tunneled between active sites...
October 4, 2016: Proceedings of the National Academy of Sciences of the United States of America
Theodorus B M Hakvoort, Youji He, Wim Kulik, Jacqueline L M Vermeulen, Suzanne Duijst, Jan M Ruijter, Jurgen H Runge, Nicolaas E P Deutz, S Eleonore Koehler, Wouter H Lamers
: Glutamine synthetase (GS) catalyzes condensation of ammonia with glutamate to glutamine. Glutamine serves, with alanine, as major nontoxic interorgan ammonia carrier. Elimination of hepatic GS expression in mice causes only mild hyperammonemia and hypoglutaminemia, but a pronounced decrease in the whole-body muscle-to-fat ratio with increased myostatin expression in muscle. Using GS-KO/Liver and control mice, and stepwise increments of enterally infused ammonia, we show that ∼35% of this ammonia is detoxified by hepatic GS and ∼35% by urea-cycle enzymes, while ∼30% is not cleared by the liver, independent of portal ammonia concentrations ≤2 mmol/L...
September 19, 2016: Hepatology: Official Journal of the American Association for the Study of Liver Diseases
Kevin A Meyer, Christopher K Neeley, Nicki A Baker, Alexandra R Washabaugh, Carmen G Flesher, Barbara S Nelson, Timothy L Frankel, Carey N Lumeng, Costas A Lyssiotis, Michelle L Wynn, Andrew D Rhim, Robert W O'Rourke
Adipocytes promote progression of multiple cancers, but their role in pancreatic intraepithelial neoplasia (PanIN) and ductal adenocarcinoma (PDAC) is poorly defined. Nutrient transfer is a mechanism underlying stromal cell-cancer crosstalk. We studied the role of adipocytes in regulating in vitro PanIN and PDAC cell proliferation with a focus on glutamine metabolism. Murine 3T3L1 adipocytes were used to model adipocytes. Cell lines derived from PKCY mice were used to model PanIN and PDAC. Co-culture was used to study the effect of adipocytes on PanIN and PDAC cell proliferation in response to manipulation of glutamine metabolism...
September 2016: Biochemistry and Biophysics Reports
YanYan Guo, YuanJun Deng, XiaoQing Li, Yong Ning, XuePing Lin, ShuiMing Guo, MeiXue Chen, Min Han
Vascular endothelial cells can survive under hypoxic and inflammatory conditions by alterations of the cellular energy metabolism. In addition to high rates of glycolysis, glutaminolysis is another important way of providing the required energy to support cellular sprouting in such situations. However, the exact mechanism in which endothelial cells upregulate glutaminolysis remains unclear. Here we demonstrated that protein phosphatase 2A (PP2A)-mediated Raf-MEK-ERK signaling was involved in glutaminolysis in endothelial cells...
2016: PloS One
Lindan Sun, Lizhu Yi, Chi Zhang, Xiaodan Liu, Shuangshuang Feng, Wenjie Chen, Jiangfeng Lan, Lijuan Zhao, Jiagang Tu, Li Lin
Snakehead fish vesiculovirus (SHVV), a member of the family Rhabdoviridae, has caused mass mortality to snakehead fish culture in China. Previous transcriptomic sequencing of SHVV-infected and non-infected striped snakehead fish cells (SSN-1) showed that glutaminase (GLS), the critical enzyme of glutamine metabolism, was up regulated upon SHVV infection. It therefore drew our attention to investigate the role of glutamine on SHVV propagation. Glutamine deprivation significantly reduced the expression of the mRNAs and proteins of SHVV, and the production of virus particles, indicating that glutamine was required for SHVV propagation...
September 6, 2016: Journal of General Virology
Ian A Clark, Bryce Vissel
The basic mechanism of the major neurodegenerative diseases, including neurogenic pain, needs to be agreed upon before rational treatments can be determined, but this knowledge is still in a state of flux. Most have agreed for decades that these disease states, both infectious and non-infectious, share arguments incriminating excitotoxicity induced by excessive extracellular cerebral glutamate. Excess cerebral levels of tumor necrosis factor (TNF) are also documented in the same group of disease states. However, no agreement exists on overarching mechanism for the harmful effects of excess TNF, nor, indeed how extracellular cerebral glutamate reaches toxic levels in these conditions...
2016: Journal of Neuroinflammation
Cambyz Irajie, Milad Mohkam, Navid Nezafat, Saeed Hosseinzadeh, Mahmood Aminlari, Younes Ghasemi
BACKGROUND: Glutaminase (EC catalyzes the hydrolytic degradation of L-glutamine to L-glutamic acid and has been introduced for cancer therapy in recent years. The present study was an in silico analysis of glutaminase to further elucidate its structure and physicochemical properties. METHODS: Forty glutaminase protein sequences from different species of Escherichia and Bacillus obtained from the UniProt Protein Database were characterized for homology search, physiochemical properties, phylogenetic tree construction, motif, superfamily search, and multiple sequence alignment...
September 2016: Iranian Journal of Medical Sciences
Dae J Kang, Genta Kakiyama, Naga S Betrapally, Jeremy Herzog, Hiroshi Nittono, Phillip B Hylemon, Huiping Zhou, Ian Carroll, Jing Yang, Patrick M Gillevet, Chunhua Jiao, Hajime Takei, William M Pandak, Takashi Iida, Douglas M Heuman, Sili Fan, Oliver Fiehn, Takao Kurosawa, Masoumeh Sikaroodi, R B Sartor, Jasmohan S Bajaj
OBJECTIVES: Rifaximin has clinical benefits in minimal hepatic encephalopathy (MHE) but the mechanism of action is unclear. The antibiotic-dependent and -independent effects of rifaximin need to be elucidated in the setting of MHE-associated microbiota. To assess the action of rifaximin on intestinal barrier, inflammatory milieu and ammonia generation independent of microbiota using rifaximin. METHODS: Four germ-free (GF) mice groups were used (1) GF, (2) GF+rifaximin, (3) Humanized with stools from an MHE patient, and (4) Humanized+rifaximin...
2016: Clinical and Translational Gastroenterology
Amira Elgogary, Qingguo Xu, Brad Poore, Jesse Alt, Sarah C Zimmermann, Liang Zhao, Jie Fu, Baiwei Chen, Shiyu Xia, Yanfei Liu, Marc Neisser, Christopher Nguyen, Ramon Lee, Joshua K Park, Juvenal Reyes, Thomas Hartung, Camilo Rojas, Rana Rais, Takashi Tsukamoto, Gregg L Semenza, Justin Hanes, Barbara S Slusher, Anne Le
Targeting glutamine metabolism via pharmacological inhibition of glutaminase has been translated into clinical trials as a novel cancer therapy, but available drugs lack optimal safety and efficacy. In this study, we used a proprietary emulsification process to encapsulate bis-2-(5-phenylacetamido-1,2,4-thiadiazol-2-yl)ethyl sulfide (BPTES), a selective but relatively insoluble glutaminase inhibitor, in nanoparticles. BPTES nanoparticles demonstrated improved pharmacokinetics and efficacy compared with unencapsulated BPTES...
September 6, 2016: Proceedings of the National Academy of Sciences of the United States of America
Jan Budczies, Carsten Denkert
Mass spectrometry and nuclear magnetic resonance-based metabolomics have been developed into mature technologies that can be utilized to analyze hundreds of biological samples in a high-throughput manner. Over the past few years, both technologies were utilized to analyze large cohorts of fresh frozen breast cancer tissues. Metabolite biomarkers were shown to separate breast cancer tissues from normal breast tissues with high sensitivity and specificity. Furthermore, the metabolome differed between hormone receptor positive (HR+) and hormone receptor negative (HR-) breast cancer, but was unchanged in HER2+ tumors compared to HER2- tumors...
2016: Recent Results in Cancer Research
Thomas Bertero, William M Oldham, Katherine A Cottrill, Sabrina Pisano, Rebecca R Vanderpool, Qiujun Yu, Jingsi Zhao, Yiyin Tai, Ying Tang, Ying-Yi Zhang, Sofiya Rehman, Masataka Sugahara, Zhi Qi, John Gorcsan, Sara O Vargas, Rajan Saggar, Rajeev Saggar, W Dean Wallace, David J Ross, Kathleen J Haley, Aaron B Waxman, Victoria N Parikh, Teresa De Marco, Priscilla Y Hsue, Alison Morris, Marc A Simon, Karen A Norris, Cedric Gaggioli, Joseph Loscalzo, Joshua Fessel, Stephen Y Chan
Dysregulation of vascular stiffness and cellular metabolism occurs early in pulmonary hypertension (PH). However, the mechanisms by which biophysical properties of the vascular extracellular matrix (ECM) relate to metabolic processes important in PH remain undefined. In this work, we examined cultured pulmonary vascular cells and various types of PH-diseased lung tissue and determined that ECM stiffening resulted in mechanoactivation of the transcriptional coactivators YAP and TAZ (WWTR1). YAP/TAZ activation modulated metabolic enzymes, including glutaminase (GLS1), to coordinate glutaminolysis and glycolysis...
September 1, 2016: Journal of Clinical Investigation
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