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Protein phosphatase 2a

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https://www.readbyqxmd.com/read/29158400/drosophila-protein-phosphatases-2a-b-wdb-and-wrd-regulate-meiotic-centromere-localization-and-function-of-the-mei-s332-shugoshin
#1
Belinda S Pinto, Terry L Orr-Weaver
Proper segregation of chromosomes in meiosis is essential to prevent miscarriages and birth defects. This requires that sister chromatids maintain cohesion at the centromere as cohesion is released on the chromatid arms when the homologs segregate at anaphase I. The Shugoshin proteins preserve centromere cohesion by protecting the cohesin complex from cleavage, and this has been shown in yeasts to be mediated by recruitment of the protein phosphatase 2A B' (PP2A B'). In metazoans, delineation of the role of PP2A B' in meiosis has been hindered by its myriad of other essential roles...
November 20, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29142109/the-ndc80-complex-targets-bod1-to-human-mitotic-kinetochores
#2
Katharina Schleicher, Michael Porter, Sara Ten Have, Ramasubramanian Sundaramoorthy, Iain M Porter, Jason R Swedlow
Regulation of protein phosphatase activity by endogenous protein inhibitors is an important mechanism to control protein phosphorylation in cells. We recently identified Biorientation defective 1 (Bod1) as a small protein inhibitor of protein phosphatase 2A containing the B56 regulatory subunit (PP2A-B56). This phosphatase controls the amount of phosphorylation of several kinetochore proteins and thus the establishment of load-bearing chromosome-spindle attachments in time for accurate separation of sister chromatids in mitosis...
November 2017: Open Biology
https://www.readbyqxmd.com/read/29133527/interaction-of-the-phosphorylated-dna-binding-domain-in-nuclear-receptor-car-with-its-ligand-binding-domain-regulates-car-activation
#3
Ryota Shizu, Jungki Min, Mack Sobhany, Lars C Pedersen, Shingo Mutoh, Masahiko Negishi
The nuclear protein constitutive active/androstane receptor (CAR or NR1I3) regulates several liver functions such as drug and energy metabolism and cell growth or death, which are often involved in the development of diseases such as diabetes and hepatocellular carcinoma. CAR undergoes a conversion from inactive homodimers to active heterodimers with retinoid X receptor alpha (RXRα), and phosphorylation of the DNA-binding domain (DBD) at Thr-38 in CAR regulates this conversion. Here, we uncovered the molecular mechanism by which this phosphorylation regulates the intramolecular interaction between CARs DBD and ligand-binding domain (LBD), enabling the homodimer-heterodimer conversion...
November 13, 2017: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/29128580/reduction-of-protein-phosphatase-2a-c%C3%AE-promotes-in-vivo-bone-formation-and-adipocyte-differentiation
#4
Kaya Yoshida, Jumpei Teramachi, Kenta Uchibe, Mika Ikegame, Lihong Qiu, Di Yang, Hirohiko Okamura
Serine/threonine protein phosphatase 2A (PP2A) regulates diverse physiological processes such as cell cycle, growth, apoptosis, and signal transduction. Previously, we demonstrated that silencing of the α-isoform of PP2A catalytic subunit (PP2A Cα) in osteoblasts accelerated osteoblast differentiation, whereas its overexpression suppressed differentiation. In this study, we examined the role of PP2A Cα in in vivo bone formation by generating transgenic mice (PP2A-Tg), in which the dominant negative form of PP2A Cα was specifically expressed in osteoblasts...
November 8, 2017: Molecular and Cellular Endocrinology
https://www.readbyqxmd.com/read/29121398/protein-phosphatase-2a-and-tau-an-orchestrated-pas-de-deux
#5
REVIEW
Goce Taleski, Estelle Sontag
The neuronal microtubule-associated protein tau serves a critical role in regulating axonal microtubule dynamics to support neuronal and synaptic functions. Furthermore, it contributes to glutamatergic regulation and synaptic plasticity. Emerging evidence also suggests that tau serves as a signaling scaffold. Tau function and subcellular localisation are tightly regulated, in part, by the orchestrated interplay between phosphorylation and dephosphorylation events. Significantly, protein phosphatase type 2A (PP2A), encompassing the regulatory PPP2R2A (or Bα) subunit, is a major brain heterotrimeric enzyme and the primary tau Ser/Thr phosphatase in vivo...
November 9, 2017: FEBS Letters
https://www.readbyqxmd.com/read/29113343/pp2a-mediates-apoptosis-or-autophagic-cell-death-in-multiple-myeloma-cell-lines
#6
Hang Zhou, Wei Luo, Chao Zeng, Yu Zhang, Liyang Wang, Wenxiu Yao, Chunlai Nie
The crosstalk between apoptosis and autophagy contributes to tumorigenesis and cancer therapy. The process by which BetA (betulinic acid), a naturally occurring triterpenoid, regulates apoptosis and autophagy as a cancer therapy is unclear. In this study, we show for the first time that protein phosphatase 2A (PP2A) acts as a switch to regulate apoptosis and autophagic cell death mediated by BetA. Under normal conditions, caspase-3 is activated by the mitochondrial pathway upon BetA treatment. Activated caspase-3 cleaves the A subunit of PP2A (PP2A/A), resulting in the association of PP2A and Akt...
October 6, 2017: Oncotarget
https://www.readbyqxmd.com/read/29107183/therapeutic-targeting-of-pp2a
#7
REVIEW
Caitlin M O'Connor, Abbey Perl, Daniel Leonard, Jaya Sangodkar, Goutham Narla
Protein phosphatase 2A (PP2A) is a major serine/threonine phosphatase that regulates many cellular processes. Given the central role of PP2A in regulating diverse biological functions and its dysregulation in many diseases, including cancer, PP2A directed therapeutics have become of great interest. The main approaches leveraged thus far can be categorized as follows: 1) inhibiting endogenous inhibitors of PP2A, 2) targeted disruption of post translational modifications on PP2A subunits, or 3) direct targeting of PP2A...
October 26, 2017: International Journal of Biochemistry & Cell Biology
https://www.readbyqxmd.com/read/29103022/increase-in-cip2a-expression-is-associated-with-cisplatin-chemoresistance-in-gastric-cancer
#8
Juanli Ji, Weiguo Zhen, Yuan Si, Wenjing Ma, Lanlan Zheng, Chen Li, Yonghong Zhang, Shanshan Qin, Te Zhang, Pengfei Liu, Xin Zheng, Ying Liu
BACKGROUND: The cancerous inhibitor of protein phosphatase 2A (CIP2A) is an oncoprotein which involves in the progression of several human malignancies. Development of cisplatin (DDP) resistance is the obstacle to an effective control of gastric cancer (GC) clinically. OBJECTIVE: We thus assessed whether CIP2A expression is associated with sensitivity of GC to DDP. METHODS: Real-time quantitative PCR, immunohistochemical analysis, or western blotting was performed to detect CIP2A expression in GC patients' tissues...
October 27, 2017: Cancer Biomarkers: Section A of Disease Markers
https://www.readbyqxmd.com/read/29091948/selection-and-validation-of-appropriate-reference-genes-for-quantitative-real-time-pcr-analysis-in-salvia-hispanica
#9
Rahul Gopalam, Sunny D Rupwate, Ajay W Tumaney
Quantitative real-time polymerase chain reaction (qRT-PCR) has become the most popular choice for gene expression studies. For accurate expression analysis, it is pertinent to select a stable reference gene to normalize the data. It is now known that the expression of internal reference genes varies considerably during developmental stages and under different experimental conditions. For Salvia hispanica, an economically important oilseed crop, there are no reports of stable reference genes till date. In this study, we chose 13 candidate reference genes viz...
2017: PloS One
https://www.readbyqxmd.com/read/29089450/mark3-mediated-phosphorylation-of-arhgef2-couples-microtubules-to-the-actin-cytoskeleton-to-establish-cell-polarity
#10
María-José Sandí, Christopher B Marshall, Marc Balan, Étienne Coyaud, Ming Zhou, Daniel M Monson, Noboru Ishiyama, Arun A Chandrakumar, José La Rose, Amber L Couzens, Anne-Claude Gingras, Brian Raught, Wei Xu, Mitsuhiko Ikura, Deborah K Morrison, Robert Rottapel
The PAR-1-MARK pathway controls cell polarity through the phosphorylation of microtubule-associated proteins. Rho-Rac guanine nucleotide exchange factor 2 (ARHGEF2), which activates Ras homolog family member A (RHOA), is anchored to the microtubule network and sequestered in an inhibited state through binding to dynein light chain Tctex-1 type 1 (DYNLT1). We showed in mammalian cells that liver kinase B1 (LKB1) activated the microtubule affinity-regulating kinase 3 (MARK3), which in turn phosphorylated ARHGEF2 at Ser(151) This modification disrupted the interaction between ARHGEF2 and DYNLT1 by generating a 14-3-3 binding site in ARHGEF2, thus causing ARHGEF2 to dissociate from microtubules...
October 31, 2017: Science Signaling
https://www.readbyqxmd.com/read/29084198/distinct-kinetics-of-serine-and-threonine-dephosphorylation-are-essential-for-mitosis
#11
Jamin B Hein, Emil P T Hertz, Dimitriya H Garvanska, Thomas Kruse, Jakob Nilsson
Protein phosphatase 2A (PP2A) in complex with B55 regulatory subunits reverses cyclin-dependent kinase 1 (Cdk1) phosphorylations at mitotic exit. Interestingly, threonine and serine residues phosphorylated by Cdk1 display distinct phosphorylation dynamics, but the biological significance remains unexplored. Here we demonstrate that the phosphothreonine preference of PP2A-B55 provides an essential regulatory element of mitotic exit. To allow rapid activation of the anaphase-promoting complex/cyclosome (APC/C) co-activator Cdc20, inhibitory phosphorylation sites are conserved as threonines while serine substitutions delay dephosphorylation and Cdc20 activation...
October 30, 2017: Nature Cell Biology
https://www.readbyqxmd.com/read/29078372/dephosphorylation-by-protein-phosphatase-2a-regulates-visual-pigment-regeneration-and-the-dark-adaptation-of-mammalian-photoreceptors
#12
Alexander V Kolesnikov, Tivadar Orban, Hui Jin, Celine Brooks, Lukas Hofmann, Zhiqian Dong, Maxim Sokolov, Krzysztof Palczewski, Vladimir J Kefalov
Resetting of G-protein-coupled receptors (GPCRs) from their active state back to their biologically inert ground state is an integral part of GPCR signaling. This "on-off" GPCR cycle is regulated by reversible phosphorylation. Retinal rod and cone photoreceptors arguably represent the best-understood example of such GPCR signaling. Their visual pigments (opsins) are activated by light, transduce the signal, and are then inactivated by a GPCR kinase and arrestin. Although pigment inactivation by phosphorylation is well understood, the enzyme(s) responsible for pigment dephosphorylation and the functional significance of this reaction remain unknown...
November 7, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/29070518/digoxin-enhances-radiation-response-in-radioresistant-a549-cells-by-reducing-protein-phosphatase-2a-pp2a
#13
Ji Young Lee, Mi-Sook Kim, Mi So Lee, Jae Eun Ju, Namhyun Chung, Youn Kyoung Jeong
Protein phosphatase 2A (PP2A) is a ubiquitous multifunctional enzyme usually known as a tumor suppressor. Recent studies have reported that although inhibition of PP2A leads to acceleration of cell growth, it also induces damaged cells to pass through the cell cycle and renders them sensitive to radiotherapy. Here, we investigated the radiosensitizing effects of digoxin as a PP2A inhibitor in two non-small cell lung cancer cell types (H460 and A549) with differential sensitivity to radiation. Digoxin inhibited the proliferation of H460 and A549 cells in a dose-dependent fashion and was especially effective on radioresistant A549 cells...
October 25, 2017: Bioscience Reports
https://www.readbyqxmd.com/read/29068100/upregulated-osterix-expression-elicited-by-runx2-and-dlx5-is-required-for-the-accelerated-osteoblast-differentiation-in-pp2a-c%C3%AE-knockdown-cells
#14
Di Yang, Hirohiko Okamura, Lihong Qiu
Serine/threonine protein phosphatase 2A (PP2A) is involved in regulating various physiological processes including cell cycle, growth, apoptosis, and signal transduction. Osteoblast differentiation is controlled by main bone specific transcription factors including Osterix, distal-less homeobox 5 (Dlx5), and Runt-related transcription factor 2 (Runx2). We previously reported that knockdown of PP2A Cα increases the expression of Osterix, leading to the accelerated osteoblast differentiation through the upregulation of bone-related genes...
October 25, 2017: Cell Biology International
https://www.readbyqxmd.com/read/29066346/characterization-of-overexpression-of-the-alternatively-spliced-isoform-of-the-protein-phosphatase-2a-catalytic-subunit-in-cells
#15
Shen Tang, Yuyang Liu, Xinhang Wang, Ziwei Liang, Haiqing Cai, Laiming Mo, Deqiang Xiao, Songchao Guo, Yiqiang Ouyang, Bin Sun, Cailing Lu, Xiyi Li
PP2Acα2 is a recently discovered PP2Acα alternative splicing isoform that can be induced following serum withdrawal. It shows enhanced binding to immunoglobulin binding protein 1 and is overexpressed in chronic lymphocytic leukemia patients. Current knowledge concerning PP2Acα2 is limited. In this study, we induced and cloned PP2Acα2 from HL-60 cells and human lymphocytes, transfected them into human embryonic kidney 293 cells and constructed a stable overexpression cell line. We found that PP2Acα2 mRNA inhibits expression of its longer isoform PP2Acα mRNA but had no effect on the final protein expression and modification of this longer isoform...
October 21, 2017: Biochemical and Biophysical Research Communications
https://www.readbyqxmd.com/read/29054680/phosphorylation-of-protein-phosphatase-2a-facilitated-an-early-stage-of-chemical-carcinogenesis
#16
Yuji Ishii, Ken Kuroda, Kohei Matsushita, Yuh Yokoo, Shinji Takasu, Aki Kijima, Takehiko Nohmi, Kumiko Ogawa, Takashi Umemura
Protein phosphatase 2A (PP2A) is a serine-threonine phosphatase that regulates cell signaling pathways. Its inactivation is correlated with tumor malignancy, possibly due to the effects on cell differentiation and malignant cell transformation. Therefore, it has been noted that PP2A could be a promising target for cancer therapy. In our previous study of the hepatocarcinogen estragole (ES), cell proliferation may be required to convert ES-specific DNA adducts to mutations. To explore the trigger for cell proliferation, gpt delta rats were administered ES by gavage at doses of 3, 30 and 300mg/kg/day for 4weeks...
October 17, 2017: Toxicology and Applied Pharmacology
https://www.readbyqxmd.com/read/29049491/dermal-hyperneury-and-multiple-sclerotic-fibromas-in-multiple-endocrine-neoplasia-type-2a-syndrome
#17
Victoria Alegría-Landa, Margarita Jo-Velasco, Mercedes Robledo, Luis Requena
Importance: Multiple endocrine neoplasia type 2 (MEN 2) syndrome is an autosomal dominant, hereditary cancer disorder caused by germline mutations in the RET (formerly MEN2A, MEN2B) proto-oncogene located on chromosomal band 10q11.21. Two distinct clinical forms have been described as the following phenotypes: multiple endocrine neoplasia type 2A (MEN 2A) and multiple endocrine neoplasia type 2B (MEN 2B) syndromes. The common and necessary nexus that defines these 2 phenotypes is the presence of medullary thyroid carcinoma (MTC)...
October 18, 2017: JAMA Dermatology
https://www.readbyqxmd.com/read/29046336/pp2a-inactivation-mediated-by-ppp2r4-haploinsufficiency-promotes-cancer-development
#18
Ward Sents, Bob Meeusen, Petar Kalev, Enrico Radaelli, Xavier Sagaert, Eline Miermans, Dorien Haesen, Caroline Lambrecht, Mieke Dewerchin, Peter Carmeliet, Jukka Westermarck, Anna Sablina, Veerle Janssens
Protein phosphatase 2A (PP2A) complexes counteract many oncogenic kinase pathways. In cancer cells, PP2A function can be compromised by several mechanisms, including sporadic mutations in its scaffolding A and regulatory B subunits or more frequently through overexpression of cellular PP2A inhibitors. Here we identify a novel genetic mechanism by which PP2A function is recurrently affected in human cancer, involving haploinsufficiency of PPP2R4, a gene encoding the cellular PP2A activator PTPA. Notably, up to 70% of cancer patients showed a heterozygous deletion or missense mutations in PPP2R4 Cancer-associated PTPA mutants exhibited decreased abilities to bind the PP2A-C subunit or activate PP2A and failed to reverse the tumorigenic phenotype induced by PTPA suppression, indicating they function as null alleles...
October 18, 2017: Cancer Research
https://www.readbyqxmd.com/read/29038598/male-specific-deficits-in-natural-reward-learning-in-a-mouse-model-of-neurodevelopmental-disorders
#19
N M Grissom, S E McKee, H Schoch, N Bowman, R Havekes, W T O'Brien, E Mahrt, S Siegel, K Commons, C Portfors, T Nickl-Jockschat, T M Reyes, T Abel
Neurodevelopmental disorders, including autism spectrum disorders, are highly male biased, but the underpinnings of this are unknown. Striatal dysfunction has been strongly implicated in the pathophysiology of neurodevelopmental disorders, raising the question of whether there are sex differences in how the striatum is impacted by genetic risk factors linked to neurodevelopmental disorders. Here we report male-specific deficits in striatal function important to reward learning in a mouse model of 16p11.2 hemideletion, a genetic mutation that is strongly associated with the risk of neurodevelopmental disorders, particularly autism and attention-deficit hyperactivity disorder...
October 17, 2017: Molecular Psychiatry
https://www.readbyqxmd.com/read/29034804/cip2a-expression-predicts-recurrences-of-tamoxifen-treated-breast-cancer
#20
Shawn Baldacchino, Laura M Wastall, Christian Saliba, Thomas A Hughes, Christian Scerri, Angelene Berwick, Valerie Speirs, Andrew M Hanby, Godfrey Grech
CIP2A is emerging as an oncoprotein overexpressed commonly across many tumours and generally correlated with higher tumour grade and therapeutic resistance. CIP2A drives an oncogenic potential through inhibiting protein phosphatase 2A, stabilizing MYC, and promoting epithelial-to-mesenchymal transition, although further biological mechanisms for CIP2A are yet to be defined. CIP2A protein expression was studied by immunohistochemistry in oestrogen receptor-positive primary breast cancers (n = 250) obtained from the Leeds Tissue Bank...
October 2017: Tumour Biology: the Journal of the International Society for Oncodevelopmental Biology and Medicine
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