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Protein phosphatase 2a

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https://www.readbyqxmd.com/read/28224476/protein-phosphatase-2a-a-double-faced-phosphatase-of-cellular-system-and-its-role-in-neurodegenerative-disorders
#1
REVIEW
Md Nematullah, M N Hoda, Farah Khan
Protein phosphatase 2A (PP2A), a ubiquitously expressed serine/threonine phosphatase, is a vitally important phosphatase for the cellular system. Structurally, it is constituted of three different subunits, namely catalytic subunit (PP2Ac), structural scaffold subunit (PP2A-A), and regulatory subunit (PP2A-B). All subunits have various isoforms, and catalytic and scaffold subunits are ubiquitously expressed, whereas regulatory subunits are more specific to tissue and cell type. It is the numerous possibilities of PP2A holoenzyme assembly with varying isoform components that make it possess a dual nature of activator or the inhibitory character in different signaling pathways, namely neural developmental pathways, Akt/protein kinase B pathway, NF-kB pathway, MAPK pathway, apoptosis pathway, and cell cycle progression to name a few...
February 21, 2017: Molecular Neurobiology
https://www.readbyqxmd.com/read/28223368/phosphatases-generate-signal-specificity-downstream-of-ssp1-kinase-in-fission-yeast
#2
Lin Deng, Mid Eum Lee, Katherine Schutt, James B Moseley
AMPK-related protein kinases (ARKs) coordinate cell growth, proliferation, and migration with environmental status. It is unclear how specific ARKs are activated at specific times. In fission yeast S. pombe, the CaMKK-like protein kinase Ssp1 promotes cell cycle progression by activating the ARK Cdr2 according to cell growth signals. Here, we demonstrate that Ssp1 activates a second ARK, Ssp2/AMPK-α, for cell proliferation in low environmental glucose. Ssp1 activates these two related targets by the same biochemical mechanism: direct phosphorylation of a conserved residue in the activation loop (Cdr2-T166 and Ssp2-T189)...
February 21, 2017: Molecular and Cellular Biology
https://www.readbyqxmd.com/read/28208772/transcriptional-and-behavioral-responses-of-zebrafish-larvae-to-microcystin-lr-exposure
#3
Eleni Tzima, Iliana Serifi, Ioanna Tsikari, Ainhoa Alzualde, Ioannis Leonardos, Thomais Papamarcaki
Microcystins are cyclic heptapeptides that constitute a diverse group of toxins produced by cyanobacteria. One of the most toxic variants of this family is microcystin-LR (MCLR) which is a potent inhibitor of protein phosphatase 2A (PP2A) and induces cytoskeleton alterations. In this study, zebrafish larvae exposed to 500 μg/L of MCLR for four days exhibited a 40% reduction of PP2A activity compared to the controls, indicating early effects of the toxin. Gene expression profiling of the MCLR-exposed larvae using microarray analysis revealed that keratin 96 (krt96) was the most downregulated gene, consistent with the well-documented effects of MCLR on cytoskeleton structure...
February 9, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/28179537/early-tyrosine-phosphorylation-events-following-adenosine-a2a-receptor-in-human-neutrophils-identification-of-regulated-pathways
#4
Miriam S Giambelluca, Marc Pouliot
Activation of the adenosine 2A receptor (A2AR) elevates intracellular levels of cAMP and acts as a physiologic inhibitor of inflammatory neutrophil functions. In this study, we looked into the impact of A2AR engagement on early phosphorylation events. Neutrophils were stimulated with well-characterized proinflammatory agonists in the absence or presence of an A2AR agonist {3-[4-[2-[ [6-amino-9-[(2R,3R,4S,5S)-5-(ethylcarbamoyl)-3,4-dihydroxy-oxolan-2-yl]purin-2-yl]amino] ethyl] phenyl] propanoic acid (CGS 21680)}, PGE2, or a mixture of the compounds RO 20-1724 and forskolin...
February 8, 2017: Journal of Leukocyte Biology
https://www.readbyqxmd.com/read/28174720/netrin-1-protects-hepatocytes-against-cell-death-through-sustained-translation-during-the-unfolded-protein-response
#5
Thomas Lahlali, Marie-Laure Plissonnier, Cristina Romero-López, Maud Michelet, Benjamin Ducarouge, Alfredo Berzal-Herranz, Fabien Zoulim, Patrick Mehlen, Romain Parent
BACKGROUND & AIMS: Netrin-1, a multifunctional secreted protein, is up-regulated in cancer and inflammation. Netrin-1 blocks apoptosis induced by the prototypical dependence receptors deleted in colorectal carcinoma and uncoordinated phenotype-5. Although the unfolded protein response (UPR) triggers apoptosis on exposure to stress, it first attempts to restore endoplasmic reticulum homeostasis to foster cell survival. Importantly, UPR is implicated in chronic liver conditions including hepatic oncogenesis...
May 2016: Cellular and Molecular Gastroenterology and Hepatology
https://www.readbyqxmd.com/read/28174209/oncoprotein-cip2a-is-stabilized-via-interaction-with-tumor-suppressor-pp2a-b56
#6
Jiao Wang, Juha Okkeri, Karolina Pavic, Zhizhi Wang, Otto Kauko, Tuuli Halonen, Grzegorz Sarek, Päivi M Ojala, Zihe Rao, Wenqing Xu, Jukka Westermarck
Protein phosphatase 2A (PP2A) is a critical human tumor suppressor. Cancerous inhibitor of PP2A (CIP2A) supports the activity of several critical cancer drivers (Akt, MYC, E2F1) and promotes malignancy in most cancer types via PP2A inhibition. However, the 3D structure of CIP2A has not been solved, and it remains enigmatic how it interacts with PP2A. Here, we show by yeast two-hybrid assays, and subsequent validation experiments, that CIP2A forms homodimers. The homodimerization of CIP2A is confirmed by solving the crystal structure of an N-terminal CIP2A fragment (amino acids 1-560) at 3...
February 7, 2017: EMBO Reports
https://www.readbyqxmd.com/read/28167675/arpp-16-is-a-striatal-enriched-inhibitor-of-protein-phosphatase-2a-regulated-by-microtubule-associated-serine-threonine-kinase-3-mast-3-kinase
#7
Erika C Andrade, Veronica Musante, Atsuko Horiuchi, Hideo Matsuzaki, A Harrison Brody, Terence Wu, Paul Greengard, Jane R Taylor, Angus C Nairn
: ARPP-16 (cAMP-Regulated Phospho-Protein of molecular weight 16 kDa) is one of several small acid-soluble proteins highly expressed in medium spiny neurons (MSNs) of striatum that are phosphorylated in response to dopamine acting via D1 receptor/protein kinase A (PKA) signaling. We show here that ARPP-16 is also phosphorylated in vitro and in vivo by microtubule-associated serine/threonine kinase 3 (MAST3 kinase), an enzyme of previously unknown function that is enriched in striatum...
February 6, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28161506/mathematical-modelling-unveils-the-essential-role-of-cellular-phosphatases-in-the-inhibition-of-raf-mek-erk-signalling-by-sorafenib-in-hepatocellular-carcinoma-cells
#8
Zuzana Saidak, Anne-Sophie Giacobbi, Christophe Louandre, Chloé Sauzay, Youcef Mammeri, Antoine Galmiche
The RAS-RAF-MEK-ERK cascade is a key oncogenic signal transduction pathway activated in many types of tumours in humans. Sorafenib, the medical treatment of reference against advanced stages of hepatocellular carcinoma (HCC), inhibits the RAF-MEK-ERK cascade in HCC cells. Based on previous studies suggesting that this cascade is an important target of sorafenib in HCC cells, we explored its regulation using mathematical modelling and ordinary differential equations. We analysed the dynamic regulation of the core components of the RAF-MEK-ERK cascade in three human HCC cell lines (Huh7, Hep3B and PLC/PRF5) with heterogeneous responses to sorafenib...
February 2, 2017: Cancer Letters
https://www.readbyqxmd.com/read/28155571/the-augmentation-of-bk-channel-activity-by-nitric-oxide-signaling-in-rat-cerebral-arteries-involves-co-localized-regulatory-elements
#9
Barry D Kyle, Ramesh C Mishra, Andrew P Braun
Large conductance, Ca(2+)-activated K(+) (BK) channels control cerebrovascular tone; however, the regulatory processes influencing these channels remain poorly understood. Here, we investigate the cellular mechanisms underlying the enhancement of BK current in rat cerebral arteries by nitric oxide (NO) signaling. In isolated cerebral myocytes, BK current magnitude was reversibly increased by sodium nitroprusside (SNP, 100 μM) and sensitive to the BK channel inhibitor, penitrem-A (100 nM). Fostriecin (30 nM), a protein phosphatase type 2A (PP2A) inhibitor, significantly prolonged the SNP-induced augmentation of BK current and a similar effect was produced by sildenafil (30 nM), a phosphodiesterase 5 (PDE5) inhibitor...
January 1, 2017: Journal of Cerebral Blood Flow and Metabolism
https://www.readbyqxmd.com/read/28138562/amphetamines-promote-mitochondrial-dysfunction-and-dna-damage-in-pulmonary-hypertension
#10
Pin-I Chen, Aiqin Cao, Kazuya Miyagawa, Nancy F Tojais, Jan K Hennigs, Caiyun G Li, Nathaly M Sweeney, Audrey S Inglis, Lingli Wang, Dan Li, Matthew Ye, Brian J Feldman, Marlene Rabinovitch
Amphetamine (AMPH) or methamphetamine (METH) abuse can cause oxidative damage and is a risk factor for diseases including pulmonary arterial hypertension (PAH). Pulmonary artery endothelial cells (PAECs) from AMPH-associated-PAH patients show DNA damage as judged by γH2AX foci and DNA comet tails. We therefore hypothesized that AMPH induces DNA damage and vascular pathology by interfering with normal adaptation to an environmental perturbation causing oxidative stress. Consistent with this, we found that AMPH alone does not cause DNA damage in normoxic PAECs, but greatly amplifies DNA damage in hypoxic PAECs...
January 26, 2017: JCI Insight
https://www.readbyqxmd.com/read/28105221/aberrant-promoter-methylation-of-cancer-related-genes-in-human-breast-cancer
#11
Liang Wu, Ye Shen, Xianzhen Peng, Simin Zhang, Ming Wang, Guisheng Xu, Xianzhi Zheng, Jianming Wang, Cheng Lu
The clinical relevance of aberrant DNA methylation is being increasingly recognized in breast cancer. The present study aimed to evaluate the promoter methylation status of seven candidate genes and to explore their potential use as a biomarker for the diagnosis of breast cancer. A total of 70 Chinese patients with breast cancer were recruited, and matched with 20 patients with benign breast disease (BBD). Methylation-specific polymerase chain reaction was performed to measure the methylation status of selected genes...
December 2016: Oncology Letters
https://www.readbyqxmd.com/read/28104351/the-sphingosine-1-phosphate-receptor-1-agonist-sew2871-reduces-tau-ser262-phosphorylation-in-rat-hippocampal-slices
#12
Frédéric St-Cyr Giguère, Suzanne Attiori Essis, Laure Chagniel, Marc Germain, Michel Cyr, Guy Massicotte
Recent studies indicate that Tau phosphorylation can be modulated by the compound FTY720-P, a global sphingosine-1-phosphate receptor (S1PR) agonist. The present work compared the effects of more selective S1PR agonists on Tau properties, using rat hippocampal slices as model system. Whereas Tau phosphorylation was not modified by the S1PR3 agonist CYM5541, Tau-Ser262 phosphorylation was significantly decreased by treatment with the S1PR1 agonist SEW2871. This effect appears to be quite restricted, as no changes in phosphorylation were elicited by the agonist on Tau-Ser199/202, Tau-Ser396 and Tau-Ser404 residues...
January 16, 2017: Brain Research
https://www.readbyqxmd.com/read/28101248/expression-of-cancerous-inhibitor-of-protein-phosphatase-2a-in-human-triple-negative-breast-cancer-correlates-with-tumor-survival-invasion-and-autophagy
#13
Shan Li, Ting-Ting Feng, Yang Guo, Xianjun Yu, Qiuyue Huang, Liang Zhang, Wei Tang, Ying Liu
Cancerous inhibitor of protein phosphatase 2A (CIP2A) is a recently characterized oncoprotein which is involved in the progression of several human malignancies. The present study aimed to investigate its biological function in human triple negative breast cancer (TNBC). The expression of CIP2A in TNBC cells was examined and it was observed that CIP2A was elevated in the TNBC cell line compared with poorly invasive breast cancer cells. CIP2A depletion in TNBC cell lines inhibited proliferation, and induced apoptosis and autophagy...
December 2016: Oncology Letters
https://www.readbyqxmd.com/read/28100785/protein-kinase-c-controls-binding-of-igo-ensa-proteins-to-protein-phosphatase-2a-in-budding-yeast
#14
Vu Thai, Noah Dephoure, Amit Weiss, Jacqueline Ferguson, Ricardo Leitao, Steven P Gygi, Douglas R Kellogg
Protein phosphatase 2A (PP2A) plays important roles in controlling mitosis in all eukaryotic cells. The form of PP2A that controls mitosis is associated with a conserved regulatory subunit that is called B55 in vertebrates and Cdc55 in budding yeast. The activity of this form of PP2A can be inhibited by binding of conserved Igo/ENSA proteins. Although the mechanisms that activate Igo/ENSA to bind to PP2A are well understood, little is known about how they are inactivated. Here, we have analyzed regulation of Igo/ENSA in the context of a checkpoint pathway that links mitotic entry to membrane growth in budding yeast...
January 18, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28098047/vitamin-a-deficiency-suppresses-fish-immune-function-with-differences-in-different-intestinal-segments-the-role-of-transcriptional-factor-nf-%C3%AE%C2%BAb-and-p38-mitogen-activated-protein-kinase-signalling-pathways
#15
Li Zhang, Lin Feng, Wei-Dan Jiang, Yang Liu, Pei Wu, Sheng-Yao Kuang, Ling Tang, Wu-Neng Tang, Yong-An Zhang, Xiao-Qiu Zhou
The present study investigated the effects of dietary vitamin A on immune function in the proximal intestine (PI), mid intestine (MI) and distal intestine (DI) of young grass carp (Ctenopharyngodon idella). Fish were fed graded levels of dietary vitamin A for 10 weeks, and then a challenge test using an injection of Aeromonas hydrophila was conducted for 14 d. The results showed that, compared with the optimum vitamin A level, vitamin A deficiency significantly decreased fish growth performance, increased enteritis morbidity, decreased intestinal innate humoral immune response and aggravated intestinal inflammation...
January 18, 2017: British Journal of Nutrition
https://www.readbyqxmd.com/read/28077320/serine-threonine-phosphatases-in-atrial-fibrillation
#16
Jordi Heijman, Shokoufeh Ghezelbash, Xander H T Wehrens, Dobromir Dobrev
Serine/threonine protein phosphatases control dephosphorylation of numerous cardiac proteins, including a variety of ion channels and calcium-handling proteins, thereby providing precise post-translational regulation of cardiac electrophysiology and function. Accordingly, dysfunction of this regulation can contribute to the initiation, maintenance and progression of cardiac arrhythmias. Atrial fibrillation (AF) is the most common heart rhythm disorder and is characterized by electrical, autonomic, calcium-handling, contractile, and structural remodeling, which include, among other things, changes in the phosphorylation status of a wide range of proteins...
January 7, 2017: Journal of Molecular and Cellular Cardiology
https://www.readbyqxmd.com/read/28073841/activation-of-eif4e-by-aurora-kinase-a-depicts-a-novel-druggable-axis-in-everolimus-resistant-cancer-cells
#17
Ahmed Katsha, Lihong Wang, Janet Arras, Omar M Omar, Jeffrey A Ecsedy, Abbes Belkhiri, Wael El-Rifai
PURPOSE: In this study, we investigated the role of Aurora kinase A (AURKA) in regulating EIF4E, cap-dependent translation, and resistance to mTOR inhibitor, RAD001 (everolimus). EXPERIMENTAL DESIGN: Tumor xenografts and in vitro cell models of upper gastrointestinal adenocarcinomas (UGCs) were used to determine the role of AURKA in activation of EIF4E and cap-dependent translation. Overexpression, knockdown, and pharmacologic inhibition of AURKA were used in vitro and in vivo...
January 10, 2017: Clinical Cancer Research: An Official Journal of the American Association for Cancer Research
https://www.readbyqxmd.com/read/28069811/tgf-%C3%AE-1-smad3-pathway-targets-pp2a-ampk-foxo1-to-regulate-hepatic-gluconeogenesis
#18
Hariom Yadav, Samir Devalaraja, Stephanie Chung, Sushil G Rane
Maintenance of glucose homeostasis is essential for normal physiology. Deviation from normal glucose levels, in either direction, increases susceptibility to serious medical complications such as hypoglycemia or diabetes. Maintenance of glucose homeostasis is achieved via functional interactions amongst various organs, liver, skeletal muscle, adipose tissue, brain and the endocrine pancreas. The liver is the primary site for endogenous glucose production, especially during states of prolonged fasting. However, enhanced gluconeogenesis is also a signature feature of type 2 diabetes (T2D)...
January 9, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/28069132/molecular-regulation-of-the-spindle-assembly-checkpoint-by-kinases-and-phosphatases
#19
G Manic, F Corradi, A Sistigu, S Siteni, I Vitale
The spindle assembly checkpoint (SAC) is a surveillance mechanism contributing to the preservation of genomic stability by monitoring the microtubule attachment to, and/or the tension status of, each kinetochore during mitosis. The SAC halts metaphase to anaphase transition in the presence of unattached and/or untensed kinetochore(s) by releasing the mitotic checkpoint complex (MCC) from these improperly-oriented kinetochores to inhibit the anaphase-promoting complex/cyclosome (APC/C). The reversible phosphorylation of a variety of substrates at the kinetochore by antagonistic kinases and phosphatases is one major signaling mechanism for promptly turning on or turning off the SAC...
2017: International Review of Cell and Molecular Biology
https://www.readbyqxmd.com/read/28067171/molecular-cloning-and-developmental-expression-patterns-of-the-striatin-gene-encoding-a-member-of-the-regulatory-subunits-for-the-protein-serine-threonine-phosphatase-2a-in-fish
#20
S-S Xie, Z-W Luo, F-Y Liu, L Liu, Z Chen, J-W Xiang, T-H Yang, R-L Qi, Y Yang, Q Nie, L Wang, Z Huang, X-H Hu, Y-F Liu, Q Sun, Y Xiao, W-J Qing, W-B Liu, Y-Z Liu, D-Y Zhang, D W-C Li
The protein phosphatase-2A (PP-2A) is one of the most important serine/threonine phosphatases in eukaryotes. The holoenzyme of PP-2A consists of three subunits: a scaffold A subunit, a catalytic C subunit and a regulatory B subunit. While both A and C subunits are coded by two different genes, the B subunits exist in 26 or more isoforms which are encoded by at least 15 different genes. Previous studies have shown that besides regulating specific PP-2A activity, the various B subunits may have other functions...
January 9, 2017: Current Molecular Medicine
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