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Teklab Gebregiworgis, Christopher Boyd Marshall, Tadateru Nishikawa, Nikolina Radulovich, María-José Sandi, Zhenhao Fang, Robert Rottapel, Ming-Sound Tsao, Mitsuhiko Ikura
Small GTPases (sGTPases) are critical switch-like regulators that mediate several important cellular functions and are often mutated in human cancers. They are activated by guanine nucleotide exchange factors (GEFs), which specifically catalyze the exchange of GTP for GDP. GEFs coordinate signaling networks in normal cells, and are frequently deregulated in cancers. sGTPase signaling pathways are complex and interconnected; however, most GEF assays do not reveal such complexity. In this communication, we describe the development of a unique real-time NMR-based multiplexed GEF assay that employs distinct isotopic labeling schemes for each sGTPase protein to enable simultaneous observation of six proteins of interest...
March 15, 2018: Journal of the American Chemical Society
Sujuan Yuan, Tiankui Qiao, Xuan Li, Xibing Zhuang, Wei Chen, Xue Chen, Qi Zhang
Unmethylated cytosine-phosphorothioate-guanine (CpG)-containing oligodeoxynucleotides (ODNs) are synthetic DNA sequences that mimic bacterial DNA, and are known to serve as ligands for Toll-like receptor 9 (TLR9). The interaction between a CpG ODNs with TLR9 activates the complex downstream cascade that contributes to exerting its function. In the present study, the results of clonogenic assays demonstrated that the activation of TLR9 by CpG ODNs significantly increased the radiosensitivity of A549 lung cancer cells, with a sensitivity enhancement ratio (SER) of 1...
April 2018: Oncology Letters
Omar Ramos-Lopez, Mirian Samblas, Fermin I Milagro, M Angeles Zulet, Maria L Mansego, Jose I Riezu-Boj, J Alfredo Martinez
Folate deficiency has been putatively implicated in the onset of diverse metabolic abnormalities, including insulin resistance, by altering epigenetic processes on key regulatory genes. The calcium/calmodulin-dependent protein kinase kinase 2 (CAMKK2) is involved in the regulation of critical metabolic processes such as adiposity and glucose homeostasis. This study hypothesized associations between low folate intakes and lower methylation levels of the CAMKK2 gene, with the presence of metabolic alterations in subjects with obesity...
February 2018: Nutrition Research
William G Robichaux, Xiaodong Cheng
This review focuses on one family of the known cAMP receptors, the exchange proteins directly activated by cAMP (EPACs), also known as the cAMP-regulated guanine nucleotide exchange factors (cAMP-GEFs). Although EPAC proteins are fairly new additions to the growing list of cAMP effectors, and relatively "young" in the cAMP discovery timeline, the significance of an EPAC presence in different cell systems is extraordinary. The study of EPACs has considerably expanded the diversity and adaptive nature of cAMP signaling associated with numerous physiological and pathophysiological responses...
April 1, 2018: Physiological Reviews
Naeem Khan, Asghari Bano, Mohammad Atikur Rahman, Bala Rathinasabapathi, Md Ali Babar
Genetic improvement for drought tolerance in chickpea requires a solid understanding of biochemical processes involved with different physiological mechanisms. The objective of this study is to demonstrate genetic variations in altered metabolic levels in chickpea varieties (tolerant and sensitive) grown under contrasting water regimes through UPLC-HRMS based untargeted metabolomic profiling. Chickpea plants were exposed to drought stress at the three-leaf stage for 25 days and the leaves were harvested at 14 days and 25 days after the imposition of drought stress...
March 13, 2018: Plant, Cell & Environment
V Vongsutilers, P M Gannett
Base modifications are known to affect the structure and function of DNA. C8-guanine adducts from various carcinogenic compounds have been shown to be potent Z-DNA inducers. Hence, it has been hypothesized that Z-DNA plays a role in cancer and other genetic diseases. In this comprehensive review, Z-DNA and the effect of prevalent C8-guanine adducts on the B-Z transition are addressed. The discoveries of Z-DNA binding proteins including ADAR1, E3L, DLM1, and PKZ have suggested the relevance of Z-DNA in living systems...
March 13, 2018: Organic & Biomolecular Chemistry
Hui Chen, Zhiying Xu, Bin Yang, Xiaoli Zhou, Hongfang Kong
OBJECTIVE: RASGRF1 is a guanine nucleotide exchange factor, which promotes the release of GDP from inactive Ras and stabilizes the apoprotein. In this study, the methylation status of RASGRF1 promoter and its correlation with clinicopathological parameters were evaluated in colorectal cancer (CRC). METHODS: Methylation-specific PCR and bisulfate-sequencing PCR were carried out to investigate the promoter methylation status of the RASGRF1 gene in tumor tissues and adjacent non-tumor tissues of 68 CRC patients...
January 2018: Annals of Clinical and Laboratory Science
Ornella Franzese, Fiorenzo Battaini, Grazia Graziani, Lucio Tentori, Maria Luisa Barbaccia, Angelo Aquino, Mario Roselli, Maria Pia Fuggetta, Enzo Bonmassar, Francesco Torino
In recent years, immune checkpoint inhibitors (ICpI) have provided the ground to bring tumor immunity back to life thanks to their capacity to afford a real clinical benefit in terms of patient's survival. Essential to ICpI success is the presence of tumor-associated neoantigens generated by non-synonymous mutations, since a direct relationship between mutation load of malignant cells and susceptibility to ICpI has been confidently established. However, it has been also suggested that high intratumor heterogeneity (ITH) associated with subclonal neoantigens could not elicit adequate immune responses...
March 9, 2018: Pharmacological Research: the Official Journal of the Italian Pharmacological Society
Zhihao Ren, Fanfeng Meng, Qiuchen Li, Yixin Wang, Xiaofeng Liu, Zhizhong Cui, Shuang Chang, Peng Zhao
BACKGROUND: Reticuloendotheliosis is an immunosuppressive disease caused by avian reticuloendotheliosis virus (REV). It is commonly found in poultry farms and has caused a notable economic loss worldwide. Despite this, there is currently no effective vaccine available to protect against REV infection. METHOD: In this study, gp90 protein derived from an REV isolated from a contaminated vaccine was co-administered with cytosine-phosphate-guanine oligodeoxynucleotide (CpG-ODN) adjuvant to hens to determine if it protects their chicks against REV infection...
March 12, 2018: Virology Journal
Hiroaki Sawamoto, Yuuki Arai, Shuhei Yamakoshi, Satoshi Obika, Eiji Kawanishi
A transglycosylation reaction of 2'-amino-locked nucleic acid (LNA) from thymine (T) to other nucleobases adenine (A), guanine (G), and 5-methylcytosine (m C) has been developed. This reaction proceeds in high yield and with high β-selectivity. The mild reaction conditions enable the coexistence of acid-labile protecting groups, including a 4,4'-dimethoxytrytyl (DMTr) group. 2'-Amino-LNAs bearing any nucleobase can now be easily synthesized.
March 12, 2018: Organic Letters
Abdul Q Khan, Shilpa Kuttikrishnan, Kodappully S Siveen, Kirti S Prabhu, Muralitharan Shanmugakonar, Hamda Al Naemi, Mohammad Haris, Said Dermime, Shahab Uddin
Abnormally activated RAS proteins are the main oncogenic driver that governs the functioning of major signaling pathways involved in the initiation and development of human malignancies. Mutations in RAS genes and or its regulators, most frequent in human cancers, are the main force for incessant RAS activation and associated pathological conditions including cancer. In general, RAS is the main upstream regulator of the highly conserved signaling mechanisms associated with a plethora of important cellular activities vital for normal homeostasis...
March 7, 2018: Seminars in Cancer Biology
Sara Lago, Matteo Nadai, Monica Rossetto, Sara N Richter
BACKGROUND: G-quadruplexes (G4s) are nucleic acids secondary structures formed in guanine-rich sequences. Anti-G4 antibodies represent a tool for the direct investigation of G4s in cells. Surface Plasmon Resonance (SPR) is a high sensitive technology, suitable for assessing the affinity between biomolecules. We here aimed at improving the orientation of an anti-G4 antibody (1H6) on SPR sensor chip for optimizing the detection of binding antigens. METHODS: SPR was employed for the characterization of 1H6 interaction with G4 and non-G4 oligonucleotides...
March 7, 2018: Biochimica et Biophysica Acta
Yuria Shinohara, Mitsutoshi Tsukimoto
Damaged tissues and cells release intracellular purine nucleotides, which serve as intercellular signaling factors. We previously showed that exogenously added adenine nucleotide (250 μM ATP) suppressed the activation of murine splenic T lymphocytes. Here, we examined the effects of other purine nucleotides/nucleosides on mouse T cell activation. First, we found that pretreatment of mouse spleen T cells with 250 μM GTP, GDP, GMP, guanosine, ITP, IDP, IMP or inosine significantly reduced the release of stimulus-inducible cytokine IL-2...
March 7, 2018: Biochemical and Biophysical Research Communications
Kanika Vanshylla, Caren Bartsch, Christoffer Hitzing, Laura Krümpelmann, Jürgen Wienands, Niklas Engels
The B cell antigen receptor (BCR) employs enzymatically inactive adaptor proteins to facilitate activation of intracellular signaling pathways. In animal model systems, adaptor proteins of the growth factor receptor-bound 2 (Grb2) family have been shown to serve critical functions in lymphocytes. However, the roles of Grb2 and the Grb2-related adaptor protein (GRAP) in human B lymphocytes remain unclear. Using TALEN-mediated gene targeting, we show that in human B cells Grb2 and GRAP amplify signaling by the immunoglobulin tail tyrosine (ITT) motif of mIgE-containing BCRs and furthermore connect immunoreceptor tyrosine-based activation motif (ITAM) signaling to activation of the Ras-controlled Erk MAP kinase pathway...
March 9, 2018: Scientific Reports
A V Chernikov, S V Gudkov, A M Usacheva, V I Bruskov
8-Oxo-7,8-dihydroguanine (8-oxo-G) is a key biomarker of oxidative damage to DNA in cells, and its genotoxicity is well-studied. In recent years, it has been confirmed experimentally that free 8-oxo-G and molecules containing it are not merely inert products of DNA repair or degradation, but they are actively involved in intracellular signaling. In this review, data are systematized indicating that free 8-oxo-G and oxidized (containing 8-oxo-G) extracellular DNA function in the body as mediators of stress signaling and initiate inflammatory and immune responses to maintain homeostasis under the action of external pathogens, whereas exogenous 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dGuo) exhibits pronounced antiinflammatory and antioxidant properties...
December 2017: Biochemistry. Biokhimii︠a︡
Micah J McCauley, Leah Furman, Catherine A Dietrich, Ioulia Rouzina, Megan E Núñez, Mark C Williams
One of the most common DNA lesions is created when reactive oxygen alters guanine. 8-oxo-guanine may bind in the anti-conformation with an opposing cytosine or in the syn-conformation with an opposing adenine paired by transversion, and both conformations may alter DNA stability. Here we use optical tweezers to measure the stability of DNA hairpins containing 8-oxoguanine (8oxoG) lesions, comparing the results to predictive models of base-pair energies in the absence of the lesion. Contrasted with either a canonical guanine-cytosine or adenine-thymine pair, an 8oxoG-cytosine base pair shows significant destabilization of several kBT...
March 7, 2018: Nucleic Acids Research
Hua Fu, Jing Hu, Min Zhang, Yuerong Wang, Hongyang Zhang, Ping Hu
For enrichment and separation of cis -diol-containing compounds from biomatrix, a new type of magnetic nanoparticles named MS-48-PBSC, whichwas facilely prepared in a one-step heterogeneous reaction. The morphology results demonstrated that the MS-48-PBSC was a spherical nanomaterial containing a core of silica-coated magnetic particle with a diameter of about 200 nm, and a cover layer of mesoporous silica with a thickness of approximate 50 nm. The characterization results showed that MS-48-PBSC presented a pore size of 4...
March 7, 2018: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Xiangqi Liu, Chen Ye, Xiaoqing Li, Naiyuan Cui, Tianzhun Wu, Shiyu Du, Qiuping Wei, Li Fu, Jiancheng Yin, Cheng-Te Lin
Potassium (K⁺) ion is an important biological substance in the human body and plays a critical role in the maintenance of transmembrane potential and hormone secretion. Several detection techniques, including fluorescent, electrochemical, and electrical methods, have been extensively investigated to selectively recognize K⁺ ions. In this work, a highly sensitive and selective biosensor based on single-layer graphene has been developed for K⁺ ion detection under Van der Pauw measurement configuration. With pre-immobilization of guanine-rich DNA on the graphene surface, the graphene devices exhibit a very low limit of detection (≈1 nM) with a dynamic range of 1 nM-10 μM and excellent K⁺ ion specificity against other alkali cations, such as Na⁺ ions...
March 7, 2018: Materials
Daniel P Morse, Colin E Nevins, Joana Aggrey-Fynn, Rick J Bravo, Herman O I Pfaeffle, Jess E Laney
Riboswitches are RNA elements found in non-coding regions of messenger RNAs that regulate gene expression through a ligand-triggered conformational change. Riboswitches typically bind tightly and specifically to their ligands, so they have the potential to serve as highly effective sensors in vitro. In B. subtilis and other gram-positive bacteria, purine nucleotide synthesis is regulated by riboswitches that bind to guanine. We modified the xpt-pbuX guanine riboswitch for use in a fluorescence quenching assay that allowed us to specifically detect and quantify guanine in vitro...
March 5, 2018: Journal of Biotechnology
Peng Liu, Chen Li, Shengyu Wang, Dunyou Wang
Water-assisted proton transfer process is a key step in guanine damage reaction by hydroxyl radical in aqueous solution. In this article, we quantitatively determined the solvent effect in water-assisted proton transfer mechanism of 8-hydroxy guanine radical using combined quantum mechanics and molecular mechanism with an explicit solvation model. Atomic-level reaction pathway was mapped, which shows a synchronized two-proton transfer mechanism between the assistance water molecule and 8-hydroxy guanine radical...
March 8, 2018: Journal of Physical Chemistry. B
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