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Hye-Jin Park, Kang-Woo Lee, Eun S Park, Stephanie Oh, Run Yan, Jie Zhang, Thomas G Beach, Charles H Adler, Michael Voronkov, Steven P Braithwaite, Jeffry B Stock, M Maral Mouradian
OBJECTIVE: Protein phosphatase 2A (PP2A) is a heterotrimeric holoenzyme composed of a catalytic C subunit, a structural A subunit, and one of several regulatory B subunits that confer substrate specificity. The assembly and activity of PP2A are regulated by reversible methylation of the C subunit. α-Synuclein, which aggregates in Parkinson disease (PD) and dementia with Lewy bodies (DLB), is phosphorylated at Ser129, and PP2A containing a B55α subunit is a major phospho-Ser129 phosphatase...
October 2016: Annals of Clinical and Translational Neurology
Li-Ming Ma, Zi-Rui Liang, Ke-Ren Zhou, Hui Zhou, Liang-Hu Qu
27-hydroxycholesterol (27-HC), the most abundant metabolite of cholesterol, is a risk factor for breast cancer. It can increase the proliferation of breast cancer cells and promote the metastasis of breast tumours in mouse models. Myc is a critical oncoprotein overexpressed in breast cancer. However, whether 27-HC affects Myc expression has not been reported. In the current study, we aimed to investigate the effects of 27-HC on Myc and the underlying mechanisms in MCF-7 breast cancer cells. Our data demonstrated that 27-HC activated Myc via increasing its protein stability...
October 14, 2016: Biochemical and Biophysical Research Communications
Leon A Sokulsky, Adam M Collison, Scott Nightingale, Anna Le Fevre, Elizabeth Percival, Malcolm R Starkey, Philip M Hansbro, Paul S Foster, Joerg Mattes
INTRODUCTION: Food antigens are common inflammatory triggers in pediatric eosinophilic esophagitis (EoE). TNF-related apoptosis-inducing ligand (TRAIL) promotes eosinophilic inflammation through the upregulation of Midline (MID)-1 and subsequent downregulation of Protein Phosphatase 2A (PP2A) but the role of this pathway in EoE that is experimentally induced by repeated food antigen challenges has not been investigated. METHODS: Esophageal mucosal biopsies were collected from children with EoE and controls and assessed for TRAIL and MID-1 protein and mRNA transcript levels...
October 13, 2016: American Journal of Physiology. Gastrointestinal and Liver Physiology
Sumita Chakrabarti, Andrew Chang, Nai-Jiang Liu, Alan R Gintzler
Caveolin-1 is the predominant structural protein of caveolae, a subset of (lipid) membrane rafts that compartmentalize cell signaling. Caveolin-1 binds most to G protein-coupled receptors and their signaling partners, thereby enhancing interactions among signaling cascade components and the relative activation of specific G protein-coupled pathways. This study reveals that chronic opioid exposure of μ-opioid receptor (MOR) expressing Chinese hamster ovary cells (MOR-CHO) and chronic in vivo morphine exposure of rat spinal cord augmented recruitment of multiple components of MOR-adenylyl cyclase (AC) stimulatory signaling by caveolin-1...
October 10, 2016: Journal of Neurochemistry
Miriam Fontanillo, Ivan Zemskov, Maximilian Häfner, Ulrike Uhrig, Francesca Salvi, Bernd Simon, Valentin Wittmann, Maja Köhn
Research and therapeutic targeting of the phosphoserine/threonine phosphatases PP1 and PP2A is hindered by the lack of selective inhibitors. The microcystin (MC) natural toxins target both phosphatases with equal potency, and their complex synthesis has complicated structure-activity relationship studies in the past. We report herein the synthesis and biochemical evaluation of 11 MC analogues, which was accomplished through an efficient strategy combining solid- and solution-phase approaches. Our approach led to the first MC analogue with submicromolar inhibitory potency that is strongly selective for PP2A over PP1 and does not require the complex lipophilic Adda group...
October 10, 2016: Angewandte Chemie
Ewa Jablonska, Patryk Gorniak, Maciej Szydlowski, Tomasz Sewastianik, Emilia Bialopiotrowicz, Anna Polak, Krzysztof Warzocha, Przemyslaw Juszczynski
B-cell receptor (BCR) signaling plays pivotal role in the pathogenesis of diffuse large B-cell lymphomas (DLBCL), and targeting the BCR pathway is a highly promising therapeutic strategy in this malignancy. Oncogenic microRNA miR-17-92 modulates multiple cellular processes such as survival, proliferation, apoptosis, angiogenesis and BCR signaling. In the present study, we identified new targets of miR-17-92, PTPROt and PP2A phosphatases, which regulate SYK and AKT activity- critical components of BCR signal transduction in DLBCL cells...
October 6, 2016: Experimental Hematology
Nameeta P Richard, Raffaella Pippa, Megan M Cleary, Alka Puri, Deanne Tibbitts, Shawn Mahmood, Dale J Christensen, Sophia Jeng, Shannon McWeeney, A Thomas Look, Bill H Chang, Jeffrey W Tyner, Michael P Vitek, María D Odero, Rosalie Sears, Anupriya Agarwal
Recent evidence suggests that inhibition of protein phosphatase 2A (PP2A) tumor suppressor activity via the SET oncoprotein contributes to the pathogenesis of various cancers. Here we demonstrate that both SET and c-MYC expression are frequently elevated in T-ALL cell lines and primary samples compared to healthy T cells. Treatment of T-ALL cells with the SET antagonist OP449 restored the activity of PP2A and reduced SET interaction with the PP2A catalytic subunit, resulting in a decrease in cell viability and c-MYC expression in a dose-dependent manner...
October 1, 2016: Oncotarget
Xiao Wang, Yawen Mu, Mengshi Sun, Junhai Han
Homeostatic regulation of the light sensor, rhodopsin, is critical for the maintenance of light sensitivity and survival of photoreceptors. The major fly rhodopsin, Rh1, undergoes light-induced endocytosis and degradation, but its protein and mRNA levels remain constant during light/dark cycles. It is not clear how translation of Rh1 is regulated. Here, we show that adult photoreceptors maintain a constant, abundant quantity of ninaE mRNA, which encodes Rh1. We demonstrate that the Fmr1 protein associates with ninaE mRNA and represses its translation...
October 4, 2016: Journal of Molecular Cell Biology
So Young Lee, Yun Young Lee, Joong Sub Choi, Mee-Sup Yoon, Joong-Soo Han
Decidualization of human endometrial stromal cells (hESCs) is crucial for successful uterine implantation and maintaining pregnancy. We previously reported that phospholipase D1 (PLD1) is required for cAMP-induced decidualization of hESCs. However, the mechanism by which phosphatidic acid (PA), the product of PLD1 action, might regulate decidualization is not known. We confirmed that PA induced-decidualization of hESCs by observing morphological changes and measuring increased levels of decidualization markers such as IGFBP1 and prolactin transcripts (p < 0...
October 3, 2016: FEBS Journal
H Liu, H Qiu, Y Song, Y Liu, H Wang, M Lu, M Deng, Y Gu, J Yin, K Luo, Z Zhang, X Jia, G Zheng, Z He
Triple-negative breast cancer (TNBC) is very aggressive and currently has no specific therapeutic targets; as a consequence, TNBC exhibits poor clinical outcome. In this study, we showed that cancerous inhibitor of protein phosphatase 2A (Cip2a) represents a promising target in TNBC because Cip2a was highly expressed in TNBC cells and tumor tissues, and its expression showed an inverse correlation with overall survival in patients with TNBC. We found that inhibition of Cip2a in TNBC cells induced cell cycle arrest at the G2/M phase, inhibited cell proliferation and delayed tumor growth in the xenograft model...
October 3, 2016: Oncogene
Edward Jd Greenwood, Nicholas J Matheson, Kim Wals, Dick Jh van den Boomen, Robin Antrobus, James C Williamson, Paul J Lehner
Viruses manipulate host factors to enhance their replication and evade cellular restriction. We used multiplex tandem mass tag (TMT)-based whole cell proteomics to perform a comprehensive time course analysis of >6,500 viral and cellular proteins during HIV infection. To enable specific functional predictions, we categorized cellular proteins regulated by HIV according to their patterns of temporal expression. We focussed on proteins depleted with similar kinetics to APOBEC3C, and found the viral accessory protein Vif to be necessary and sufficient for CUL5-dependent proteasomal degradation of all members of the B56 family of regulatory subunits of the key cellular phosphatase PP2A (PPP2R5A-E)...
September 30, 2016: ELife
Luis G Rabaneda, Noelia Geribaldi-Doldán, Maribel Murillo-Carretero, Manuel Carrasco, José M Martínez-Salas, Cristina Verástegui, Carmen Castro
Hyperhomocysteinemia reduces neurogenesis in the adult mouse brain. Homocysteine (Hcy) inhibits postnatal neural progenitor cell (NPC) proliferation by specifically impairing the fibroblast growth factor receptor (FGFR)-Erk1/2-cyclin E signaling pathway. We demonstrate herein that the inhibition of FGFR-dependent NPC proliferation induced by Hcy is mediated by its capacity to alter the cellular methylation potential. Our results show that this alteration modified the expression pattern and activity of Sprouty2 (Spry2), a negative regulator of the above mentioned pathway...
September 26, 2016: Biochimica et Biophysica Acta
Olivier Calvayrac, Anne Pradines, Gilles Favre
Metastatic dissemination is the cause of death in the vast majority of cancers, including lung cancers. In order to metastasize, tumor cells must undergo a well-known series of changes, however the molecular details of how they manage to overcome the barriers at each stage remain incomplete. One critical step is acquiring the ability to migrate through the extracellular matrix. Loss of expression of the RAS-related small GTPase RHOB is a common feature of lung cancer progression, and we recently reported that this induces an epithelial-to-mesenchymal transition (EMT) that is dependent on SLUG overexpression and E-Cadherin inhibition and is characterized by 3-dimensional cell shape reorganization and the increased invasiveness of bronchial cells...
September 27, 2016: Small GTPases
Rongbin Hu, Yinfeng Zhu, Jia Wei, Jian Chen, Huazhong Shi, Guoxin Shen, Hong Zhang
Protein phosphatase 2A (PP2A) is an enzyme consisting of three subunits: a scaffolding A subunit, a regulatory B subunit, and a catalytic C subunit. PP2As were shown to play diverse roles in eukaryotes. In this study, the function of the Arabidopsis PP2A-C5 gene that encodes the catalytic subunit 5 of PP2A was studied using both loss-of-function and gain-of-function analyses. Loss-of-function mutant pp2a-c5-1 displayed more impaired growth during root and shoot development, whereas overexpression of PP2A-C5 conferred better root and shoot growth under different salt treatments, indicating that PP2A-C5 plays an important role in plant growth under salt conditions...
September 27, 2016: Plant, Cell & Environment
Amanpreet Kaur, Oxana Denisova, Xi Qiao, Mikael Jumppanen, Emilia Peuhu, Shafiq U Ahmed, Olayinka Raheem, Hannu K Haapasalo, John Eriksson, Anthony J Chalmers, Pirjo M Laakkonen, Jukka Westermarck
Glioblastoma multiforme (GBM) lacks effective therapy options. Although deregulated kinase pathways are drivers of malignant progression in GBM, glioma cells exhibit intrinsic resistance towards many kinase inhibitors, and the molecular basis of this resistance remains poorly understood. Here we show that overexpression of the protein phosphatase 2A (PP2A) inhibitor protein PME-1 drives resistance of glioma cells to various multikinase inhibitors. The PME-1-elicited resistance was dependent on specific PP2A complexes and was mediated by a decrease in cytoplasmic HDAC4 activity...
September 26, 2016: Cancer Research
Seong M Kim, Saurabh G Roy, Bin Chen, Tiffany M Nguyen, Ryan J McMonigle, Alison N McCracken, Yanling Zhang, Satoshi Kofuji, Jue Hou, Elizabeth Selwan, Brendan T Finicle, Tricia T Nguyen, Archna Ravi, Manuel U Ramirez, Tim Wiher, Garret G Guenther, Mari Kono, Atsuo T Sasaki, Lois S Weisman, Eric O Potma, Bruce J Tromberg, Robert A Edwards, Stephen Hanessian, Aimee L Edinger
Oncogenic mutations drive anabolic metabolism, creating a dependency on nutrient influx through transporters, receptors, and macropinocytosis. While sphingolipids suppress tumor growth by downregulating nutrient transporters, macropinocytosis and autophagy still provide cancer cells with fuel. Therapeutics that simultaneously disrupt these parallel nutrient access pathways have potential as powerful starvation agents. Here, we describe a water-soluble, orally bioavailable synthetic sphingolipid, SH-BC-893, that triggers nutrient transporter internalization and also blocks lysosome-dependent nutrient generation pathways...
September 26, 2016: Journal of Clinical Investigation
Walker M McHugh, William W Russell, Andrew J Fleszar, Paul E Rodenhouse, Skyler P Rietberg, Lei Sun, Thomas P Shanley, Timothy T Cornell
Acute Respiratory Distress Syndrome (ARDS) remains a leading cause of morbidity and mortality in both adult and pediatric intensive care units. A key event in the development of ARDS is neutrophil recruitment into the lungs leading to tissue damage and destruction. Interleukin-8 (IL-8) is the major human chemokine responsible for neutrophil recruitment into the lungs. Protein phosphatase 2A (PP2A) has been shown to be a key regulator of the mitogen-activated protein kinase (MAPK) cascades, which control the production of IL-8...
September 16, 2016: American Journal of Physiology. Lung Cellular and Molecular Physiology
Julie H Wu, Rebecca A Simonette, Harrison P Nguyen, Peter L Rady, Stephen K Tyring
BRAF inhibitors are highly effective therapies in treating a subset of melanomas but are associated with induction of secondary cutaneous squamous cell carcinoma (cSCC). Recently, Human Polyomavirus 6 (HPyV6) was found to actively express viral proteins in BRAF inhibitor-induced cSCCs; however, the specific cellular mechanisms by which HPyV6 may facilitate neoplastic cell growth require further investigation. The current study describes a novel pathogenic mechanism of action for HPyV6 small tumor (sT) antigen which involves binding to protein phosphatase 2A (PP2A) via its WFG motif and zinc binding sites...
September 15, 2016: Journal of Medical Virology
Ritam Chatterjee, Sukalpa Chattopadhyay, Sujata Law
Aplastic anemia, the paradigm of bone marrow failure, is characterized by pancytopenic peripheral blood and hypoplastic bone marrow. Among various etiologies, inappropriate use of DNA alkylating drugs like cyclophosphamide and busulfan often causes the manifestation of the dreadful disease. Cell cycle impairment in marrow hematopoietic stem/progenitor compartment together with cellular apoptosis has been recognized as culpable factors behind aplastic pathophysiologies. However, the intricate molecular mechanisms remain unrevealed till date...
November 2016: Molecular and Cellular Biochemistry
M Kasim Diril, Xavier Bisteau, Mayumi Kitagawa, Matias J Caldez, Sheena Wee, Jayantha Gunaratne, Sang Hyun Lee, Philipp Kaldis
The Greatwall kinase/Mastl is an essential gene that indirectly inhibits the phosphatase activity toward mitotic Cdk1 substrates. Here we show that although Mastl knockout (MastlNULL) MEFs enter mitosis, they progress through mitosis without completing cytokinesis despite the presence of misaligned chromosomes, which causes chromosome segregation defects. Furthermore, we uncover the requirement of Mastl for robust spindle assembly checkpoint (SAC) maintenance since the duration of mitotic arrest caused by microtubule poisons in MastlNULL MEFs is shortened, which correlates with premature disappearance of the essential SAC protein Mad1 at the kinetochores...
September 2016: PLoS Genetics
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