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substrate inhibition

Yanfen Fang, Yannan Kong, Jianbei Xi, Mengli Zhu, Tong Zhu, Tongtong Jiang, Wenhao Hu, Mingliang Ma, Xiongwen Zhang
NEK2 is a conserved mitotic regulator critical for cell cycle progression. Aberrant expression of NEK2 has been found in a variety of human cancers, making it an attractive molecular target for the design of novel anticancer therapeutics. In the present study, we have identified a novel compound MBM-5, which was found to bind to NEK2 with high affinity by docking simulations study. MBM-5 potently inhibited NEK2 kinase activity in vitro in a concentration-dependent manner. MBM-5 also suppressed cellular NEK2 kinase activity, as evidenced by the decreased phosphorylation of its substrate Hec1 on S165 in a concentration- and time-dependent manner...
October 15, 2016: Oncotarget
Tong Zhou, Luke Erber, Bing Liu, Yankun Gao, Hai-Bin Ruan, Yue Chen
Proline hydroxylation is a critical cellular mechanism regulating oxygen-response pathways in tumor initiation and progression. Yet, its substrate diversity and functions remain largely unknown. Here, we report a system-wide analysis to characterize proline hydroxylation substrates in cancer cells using an immunoaffinity-purification assisted proteomics strategy. We identified 562 sites from 272 proteins in HeLa cells. Bioinformatic analysis revealed that proline hydroxylation substrates are significantly enriched with mRNA processing and stress-response cellular pathways with canonical and diverse flanking sequence motifs...
October 13, 2016: Oncotarget
Cristina Puy, Erik I Tucker, Ivan S Ivanov, David Gailani, Stephanie A Smith, James H Morrissey, András Gruber, Owen J T McCarty
INTRODUCTION: Factor (F) XI supports both normal human hemostasis and pathological thrombosis. Activated FXI (FXIa) promotes thrombin generation by enzymatic activation of FXI, FIX, FX, and FV, and inactivation of alpha tissue factor pathway inhibitor (TFPIα), in vitro. Some of these reactions are now known to be enhanced by short-chain polyphosphates (SCP) derived from activated platelets. These SCPs act as a cofactor for the activation of FXI and FV by thrombin and FXIa, respectively...
2016: PloS One
Erik Richter, Manuela Harms, Katharina Ventz, Rolf Nölker, Martin J Fraunholz, Jörg Mostertz, Falko Hochgräfe
Internalization of Staphylococcus aureus by non-professional phagocytic cells is a major suspected cause of persistent and difficult-to-treat infections, including pneumonia. In this study, we established an infection model with 16HBE14o- human bronchial epithelial cells and demonstrated internalization, escape from phagosomal clearance and intracellular replication of S. aureus HG001 within the first four hours post-infection. We used quantitative phosphoproteomics to identify characteristic signaling networks in the host at different infection stages...
October 20, 2016: Journal of Proteome Research
Mandy Beyer, Nicole Kiweler, Siavosh Mahboobi, Oliver H Krämer
Histone deacetylases (HDACs) catalyze the deacetylation of lysine residues in their target proteins. This biochemical modification can have profound effects on the functions of these proteins and a dysregulation of HDAC activity contributes to severe diseases, including neoplastic transformation. In the following chapter, we present a strategy that allows to distinguish between the inhibition of the class I HDACs HDAC1, 2, and 3 and of the class IIb HDAC HDAC6. This method is based on Western blot and relies on the detection of hyperacetylated substrates of class I or class IIb HDACs in lysates from cells that were treated with histone deacetylase inhibitors (HDACi)...
2017: Methods in Molecular Biology
Fabian Treude, Tobias Gladbach, Jacqueline Plaster, Jörg Hartkamp
Aberrant histone deacetylase (HDAC) activity often correlates with neoplastic transformation and inhibition of HDACs by small molecules has emerged as a promising strategy to treat hematological malignancies in particular. Treatment with HDAC inhibitors (HDACis) often prompts tumor cells to undergo apoptosis, thereby causing a caspase-dependent cleavage of target proteins. An unexpectedly large number of proteins are in vivo caspase substrates and defining caspase-mediated substrate specificity is a major challenge...
2017: Methods in Molecular Biology
FangFang, Hongyan Li, Tingting Qin, Min Li, Shiping Ma
The impaired insulin signaling has been recognized as a common pathogenetic mechanism between diabetes and Alzheimer's disease (AD). In the progression of AD, brain is characterized by defective insulin receptor substrate-1 (IRS-1) and increased oxidative stress. Thymol, a monoterpene phenol isolated from medicinal herbs, has exhibited robust neuroprotective effects. The present study was designed to investigate the protective effect of thymol on HFD-induced cognitive deficits, and explore the possible mechanisms...
October 20, 2016: Metabolic Brain Disease
Yong Xie, Yi Zhang, Zebin Guo, Hongliang Zeng, Baodong Zheng
This study aimed to investigate the effects of total alkaloids from Nelumbinis Plumula (NPA) on insulin resistance (IR) of high-fat diet- (HFD-) induced nonalcoholic fatty liver disease (NAFLD). Rats were fed with HFD for 8 weeks to induce NAFLD. Then, the effect of NPA on ameliorating IR in HFD-induced NAFLD was evaluated. Fasting serum insulin was determined using an enzyme-linked immunosorbent assay (ELISA) kit for insulin following the manufacturer's protocol. Some inflammatory cytokines such as tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) were determined using ELISA kits to assess the inflammatory burden in rats...
2016: Journal of Diabetes Research
Shekhar Dethe, M Deepak, Amit Agarwal
BACKGROUND: Bacopa monnieri (L.) Wettst., commonly known as Brahmi, is renowned in Indian traditional system for its potent memory enhancing activity, which has been validated by various scientific studies. OBJECTIVE: The objective of this study was to understand the molecular mechanism of memory enhancing activity of BacoMind(®) (BM), a standardized extract of B. monnieri. MATERIALS AND METHODS: BM was screened in vitro in a panel of cell-free and receptor-transfected cell assays...
July 2016: Pharmacognosy Magazine
Bera Rammohan, Karmakar Samit, Das Chinmoy, Saha Arup, Kundu Amit, Sarkar Ratul, Karmakar Sanmoy, Adhikari Dipan, Sen Tuhinadri
BACKGROUND: Traditionally GS is used to treat diabetes mellitus. Drug-herb interaction of GS via cytochrome P450 enzyme system by substrate cocktail method using HLM has not been reported. OBJECTIVE: To evaluate the in-vitro modulatory effects of GS extracts (aqueous, methanol, ethyl acetate, chloroform and n-hexane) and deacylgymnemic acid (DGA) on human CYP1A2, 2C8, 2C9, 2D6 and 3A4 activities in HLM. MATERIAL AND METHODS: Probe substrate-based LCMS/MS method was established for all CYPs...
July 2016: Pharmacognosy Magazine
Laura Acquasaliente, Daniele Peterle, Simone Tescari, Nicola Pozzi, Vittorio Pengo, Vincenzo De Filippis
: β2-Glycoprotein I (β2GpI) is the major autoantigen in the antiphospholipid syndrome, a thrombotic autoimmune disease. Nonetheless, the physiological role of β2GpI is still unclear. In a recent work, we have shown that β2GpI selectively inhibits the procoagulant functions of human a-thrombin (αT) (i.e. prolongs fibrin clotting time, tc, and inhibits αT-induced platelets aggregation) without affecting the unique anticoagulant activity of the protease, i.e. the proteolytic generation of the anticoagulant protein C (PC) from the PC zymogen, which interacts with αT exclusively at the protease catalytic site...
October 19, 2016: Biochemical Journal
Jie Wang, Junfeng Wan, Haisong Li, Hongli Li, Christophe Dagot, Yan Wang
The potential of anoxic biological arsenite oxidation with nitrate as the sole electron acceptor was tested by using the acclimatized activated sludge which was chronically exposed under arsenite and nitrate coexisted aquatic environment. The activated sludge cultivated in a sequencing batch reactor was fed with arsenite and nitrate as the main substrates over six months. A series of batch experiments were conducted with acclimated sludge. Results showed that no obvious inhibition was observed in the anoxic arsenite oxidation linked to nitrate and nitrite reduction at the concentration of arsenite up to 35 mg As(III) L(-1)...
October 19, 2016: Environmental Technology
Yong-Chao Ma, Zhi-Xin Wang, Shao-Ju Jin, Yan-Xin Zhang, Guo-Qiang Hu, Dong-Tao Cui, Jiang-Shuan Wang, Min Wang, Fu-Qing Wang, Zhi-Jun Zhao
Both tyrosine kinase and topoisomerase II (TopII) are important anticancer targets, and their respective inhibitors are widely used in cancer therapy. However, some combinations of anticancer drugs could exhibit mutually antagonistic actions and drug resistance, which further limit their therapeutic efficacy. Here, we report that HMNE3, a novel bis-fluoroquinolone chalcone-like derivative that targets both tyrosine kinase and TopII, induces tumor cell proliferation and growth inhibition. The viabilities of 6 different cancer cell lines treated with a range of HMNE3 doses were detected using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay...
2016: PloS One
Max C Petersen, Anila K Madiraju, Brandon M Gassaway, Michael Marcel, Ali R Nasiri, Gina Butrico, Melissa J Marcucci, Dongyan Zhang, Abudukadier Abulizi, Xian-Man Zhang, William Philbrick, Stevan R Hubbard, Michael J Jurczak, Varman T Samuel, Jesse Rinehart, Gerald I Shulman
Nonalcoholic fatty liver disease (NAFLD) is a risk factor for type 2 diabetes (T2D), but whether NAFLD plays a causal role in the pathogenesis of T2D is uncertain. One proposed mechanism linking NAFLD to hepatic insulin resistance involves diacylglycerol-mediated (DAG-mediated) activation of protein kinase C-ε (PKCε) and the consequent inhibition of insulin receptor (INSR) kinase activity. However, the molecular mechanism underlying PKCε inhibition of INSR kinase activity is unknown. Here, we used mass spectrometry to identify the phosphorylation site Thr1160 as a PKCε substrate in the functionally critical INSR kinase activation loop...
October 17, 2016: Journal of Clinical Investigation
Rebba C Boswell-Casteel, Franklin A Hays
Equilibrative nucleoside transporters (ENTs) are polytopic integral membrane proteins that mediate the transport of nucleosides, nucleobases, and therapeutic analogs. The best-characterized ENTs are the human transporters hENT1 and hENT2. However, non-mammalian eukaryotic ENTs have also been studied (e.g., yeast, parasitic protozoa). ENTs are major pharmaceutical targets responsible for modulating the efficacy of more than 30 approved drugs. However, the molecular mechanisms and chemical determinants of ENT-mediated substrate recognition, binding, inhibition, and transport are poorly understood...
October 19, 2016: Nucleosides, Nucleotides & Nucleic Acids
Scott J Hughes, Leanne Barnard, Katayoun Mottaghi, Wolfram Tempel, Tetyana Antoshchenko, Bum Soo Hong, Abdellah Allali-Hassani, David Smil, Masoud Vedadi, Erick Strauss, Hee-Won Park
The potent antistaphylococcal activity of N-substituted pantothenamides (PanAms) has been shown to at least partially be due to the inhibition of Staphylococcus aureus's atypical type II pantothenate kinase (SaPanKII), the first enzyme of coenzyme A biosynthesis. This mechanism of action follows from SaPanKII having a binding mode for PanAms that is distinct from those of other PanKs. To dissect the molecular interactions responsible for PanAm inhibitory activity, we conducted a mini SAR study in tandem with the cocrystallization of SaPanKII with two classic PanAms (N5-Pan and N7-Pan), culminating in the synthesis and characterization of two new PanAms, N-Pip-PanAm and MeO-N5-PanAm...
September 9, 2016: ACS Infectious Diseases
Suzanne Vigneron, Perle Robert, Khaled Hached, Lena Sundermann, Sophie Charrasse, Jean-Claude Labbé, Anna Castro, Thierry Lorca
Entry into mitosis requires the coordinated activation of various protein kinases and phosphatases that together activate sequential signaling pathways allowing entry, progression and exit of mitosis. The limiting step is thought to be the activation of the mitotic Cdk1-cyclin B kinase. However, this model has recently evolved with new data showing that in addition to the Cdk1-cyclin B complex, Greatwall (Gwl) kinase is also required to enter into and maintain mitosis. This new concept proposes that entry into mitosis is now based on the combined activation of both kinases Cdk1-cyclin B and Gwl, the former promoting massive phosphorylation of mitotic substrates and the latter inhibiting PP2A-B55 phosphatase responsible for dephosphorylation of these substrates...
2016: International Journal of Developmental Biology
Jia Yin, Haichuan Duan, Joanne Wang
Renal transporter-mediated drug-drug interactions (DDIs) are of significant clinical concerns as they can adversely impact drug disposition, efficacy and toxicity. Emerging evidence suggests that human renal organic cation transporter 2 (hOCT2) and multidrug and toxin extrusion proteins 1 and 2-K (hMATE1/2-K) exhibit substrate-dependent inhibition but the impact on renal drug secretion and intracellular accumulation is unknown. Using metformin and atenolol as the probe substrates, we found that the classic inhibitors (e...
October 6, 2016: Journal of Pharmacology and Experimental Therapeutics
Tania E Perez Jimenez, Katrina L Mealey, Tamara L Grubb, Stephen A Greene, Michael H Court
Tramadol is widely used to manage mild to moderately painful conditions in dogs. However, this use is controversial since clinical efficacy studies in dogs showed conflicting results, while pharmacokinetic studies demonstrated relatively low circulating concentrations of O-desmethyltramadol (M1). Analgesia has been attributed to the opioid effects of M1, while tramadol and the other major metabolite (N-desmethyltramadol, M2) are considered inactive at opioid receptors. The aims of this study were to determine whether cytochrome P450 (CYP) dependent M1 formation by dog liver microsomes is slower compared with cat and human liver microsomes; and identify the CYPs responsible for M1 and M2 formation in canine liver...
October 6, 2016: Drug Metabolism and Disposition: the Biological Fate of Chemicals
Ming Li, Inge A M de Graaf, Marina H de Jager, Geny M M Groothuis
Although intestinal P-glycoprotein (P-gp) has been extensively studied in vitro and in animals, its activity and the consequences of P-gp inhibition for drug disposition and toxicity in humans are still difficult to accurately extrapolate from these studies. Moreover, existing in vitro models do not take into consideration that the intestine is heterogeneous with respect to P-gp expression. Recently, we reported rat precision-cut intestinal slices (PCIS) as a physiological ex vivo model to study the regional gradient of P-gp activity and inhibition...
October 19, 2016: Biopharmaceutics & Drug Disposition
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