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pp2a autoimmunity

Sokratis A Apostolidis, Noé Rodríguez-Rodríguez, Abel Suárez-Fueyo, Nikolina Dioufa, Esra Ozcan, José C Crispín, Maria G Tsokos, George C Tsokos
Homeostasis of the immune system depends on the proper function of regulatory T cells (T(reg) cells). Compromised suppressive activity of T(reg) cells leads to autoimmune disease and graft rejection and promotes anti-tumor immunity. Here we report a previously unrecognized requirement for the serine-threonine phosphatase PP2A in the function of T(reg) cells. T(reg) cells exhibited high PP2A activity, and T(reg) cell-specific ablation of the PP2A complex resulted in a severe, multi-organ, lymphoproliferative autoimmune disorder...
May 2016: Nature Immunology
Bo Peng, Yurong Chai, Yang Li, Xinxin Liu, Jianying Zhang
BACKGROUND: Cancerous inhibitor of PP2A (CIP2A) is a recently characterized oncoprotein, which promotes cancer cell proliferation. But the role of CIP2A in lung cancer progression is still not well understood. METHODS: The expression level of CIP2A in lung cancer tissues was examined by immunohistochemistry. CIP2A-associated cell proliferation was performed by knock down or overexpression of CIP2A in lung cancer cells. Phospho-array was used to screen kinase candidates related to expression change of CIP2A...
2015: BMC Cancer
Qingyu Zeng, Hai Zhang, Jiamin Qin, Zhigang Xu, Lin Gui, Beibei Liu, Chunxiao Liu, Chong Xu, Wen Liu, Shuangquan Zhang, Shile Huang, Long Chen
B-cell activating factor (BAFF) is involved in not only physiology of normal B cells, but also pathophysiology of aggressive B cells related to malignant and autoimmune diseases. Rapamycin, a lipophilic macrolide antibiotic, has recently shown to be effective in the treatment of human lupus erythematosus. However, how rapamycin inhibits BAFF-stimulated B-cell proliferation and survival has not been fully elucidated. Here, we show that rapamycin inhibited human soluble BAFF (hsBAFF)-induced cell proliferation and survival in normal and B-lymphoid (Raji and Daudi) cells by activation of PP2A and inactivation of Erk1/2...
December 2015: Cellular and Molecular Life Sciences: CMLS
Y A Lashine, S Salah, H R Aboelenein, A I Abdelaziz
MicroRNA-155 is involved in immune cell, differentiation, maturation and function. MiR-155 showed variable dysregulated expression in autoimmune diseases such as systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA) patients. MiR-155 was previously confirmed to directly target CAMP response element binding protein (CREB), which was previously identified as a positive regulator of protein phosphatase 2A (PP2A). PP2A is a key negative regulator of interleukin-2, which is an important immune modulator and was previously shown to be decreased in SLE...
March 2015: Lupus
Rebecca Breuer, Michael S Becker, Markus Brechmann, Thomas Mock, Rüdiger Arnold, Peter H Krammer
NF-κB is an important transcription factor in the immune system, and aberrant NF-κB activity contributes to malignant diseases and autoimmunity. In T cells, NF-κB is activated upon TCR stimulation, and signal transduction to NF-κB activation is triggered by a cascade of phosphorylation events. However, fine-tuning and termination of TCR signaling are only partially understood. Phosphatases oppose the role of kinases by removing phosphate moieties. The catalytic activity of the protein phosphatase PP2A has been implicated in the regulation of NF-κB...
May 23, 2014: Journal of Biological Chemistry
Dingfang Liang, Qingyu Zeng, Zhigang Xu, Hai Zhang, Lin Gui, Chong Xu, Sujuan Chen, Shuangquan Zhang, Shile Huang, Long Chen
B-cell activating factor (BAFF) is involved in not only the physiology of normal B cells, but also the pathophysiology of aggressive B cells related to malignant and autoimmune diseases. However, how excessive BAFF promotes aggressive B-cell proliferation and survival is not well understood. Here we show that excessive human soluble BAFF (hsBAFF) enhanced cell proliferation and survival in normal and B-lymphoid (Raji) cells, which was associated with suppression of PP2A, resulting in activation of Erk1/2. This is supported by the findings that pretreatment with U0126 or PD98059, expression of dominant negative MKK1, or overexpression of PP2A prevented hsBAFF-induced activation of Erk1/2 and cell proliferation/viability in the cells...
January 15, 2014: Biochemical Pharmacology
José C Crispín, Sokratis A Apostolidis, Florencia Rosetti, Marton Keszei, Ninghai Wang, Cox Terhorst, Tanya N Mayadas, George C Tsokos
The contribution of individual molecular aberrations to the pathogenesis of systemic lupus erythematosus (SLE), an autoimmune disease that affects multiple organs, is often difficult to evaluate because of the presence of abundant confounding factors. To assess the effect of increased expression of the phosphatase protein phosphatase 2A (PP2A) in T cells, as recorded in SLE patients, we generated a transgenic mouse that overexpresses the PP2Ac subunit in T cells. The transgenic mouse displays a heightened susceptibility to immune-mediated glomerulonephritis in the absence of other immune defects...
April 15, 2012: Journal of Immunology: Official Journal of the American Association of Immunologists
Li Endong, Jin Shijie, Yoshifumi Sonobe, Ma Di, Li Hua, Jun Kawanokuchi, Tetsuya Mizuno, Akio Suzumura
Carbenoxolone (CBX) is a widely used gap-junction inhibitor. We have previously shown that treatment with CBX significantly delayed the onset of experimental autoimmune encephalomyelitis (EAE). However, the mechanism by which CBX delays the onset of EAE remains to be elucidated. Here, we show that CBX specifically inhibits the production of IL-23 by dendritic cells (DCs) and microglia in vitro. CBX treatment significantly reduced the population of Th17 cells in EAE mice. Furthermore, CBX downregulated the expression of IL-23 p19 via increased production of protein phosphatase 2A (PP2A)...
December 15, 2011: Journal of Neuroimmunology
José C Crispín, Sokratis A Apostolidis, Melissa I Finnell, George C Tsokos
The activity and substrate specificity of the ubiquitously expressed phosphatase PP2A is determined by the type of regulatory (B) subunit that couples to the catalytic/scaffold core of the enzyme. We determined that the Bβ subunit (PPP2R2B) is expressed in resting T cells, its transcription is down-regulated during T-cell activation, and up-regulated in conditions of low IL-2. Specifically, high levels of PP2A Bβ were produced during IL-2 deprivation-induced apoptosis, whereas Fas ligation had no effect. Forced expression of the Bβ subunit in primary human T cells was sufficient to induce apoptosis, whereas silencing using siRNA protected activated T cells from IL-2 withdrawal-induced cell death...
July 26, 2011: Proceedings of the National Academy of Sciences of the United States of America
Erno Lindfors, Peddinti V Gopalacharyulu, Eran Halperin, Matej Oresic
Recent clinical evidence suggests important role of lipid and amino acid metabolism in early pre-autoimmune stages of type 1 diabetes pathogenesis. We study the molecular paths associated with the incidence of insulitis and type 1 diabetes in the Non-Obese Diabetic (NOD) mouse model using available gene expression data from the pancreatic tissue from young pre-diabetic mice. We apply a graph-theoretic approach by using a modified color coding algorithm to detect optimal molecular paths associated with specific phenotypes in an integrated biological network encompassing heterogeneous interaction data types...
2009: PloS One
Diana Gómez-Martín, Mariana Díaz-Zamudio, José Carlos Crispín, Jorge Alcocer-Varela
IL-2 plays a key role in setting the balance between immunity and tolerance. This cytokine has a dual role as the regulator of the two main phases of the immune response (proliferative and suppressive). Likewise, activation induced cell death and the induction and maintenance of regulatory T cells are the tolerance mechanisms regulated by IL-2, which convey the link between IL-2 abnormalities and the development of autoimmune disorders, such as systemic lupus erythematosus (SLE). Particularly, in SLE murine models and in humans, deficiency in IL-2 synthesis and activity has been proven...
September 2009: Autoimmunity Reviews
K Heese, T Yamada, H Akatsu, T Yamamoto, K Kosaka, Y Nagai, T Sawada
Active cell death ('apoptosis' or 'programmed cell death') is essential in the development and homeostasis of multicellular organisms and abnormal inhibition of apoptosis is an indicator of cancer and autoimmune diseases, whereas excessive cell death might be implicated in neurodegenerative disorders such as Alzheimer's disease (AD). Using bioinformatics-, Western-blotting-, yeast-two-hybrid-system-, polymerase chain reaction (PCR)-, and fluorescence microscopy-analyses, we demonstrate here that the neuroprotective protein p60TRP (p60-transcription-regulator-protein) is a basic helix-loop-helix (bHLH) domain-containing member of a new protein family that interacts with the Ran-binding-protein-5 (RanBP5) and the protein-phosphatase-2A (PP2A)...
April 1, 2004: Journal of Cellular Biochemistry
S A Rutjes, P J Utz, A van der Heijden, C Broekhuis, W J van Venrooij, G J Pruijn
In the past few years, a role for apoptotic processes in the development of autoimmune diseases has been suggested. An increasing number of cellular proteins, which are modified during apoptosis, has been described, and many of these proteins have been identified as autoantigens. We have studied the effects of apoptosis on the La protein in more detail and for the first time demonstrate that this autoantigen is rapidly dephosphorylated after the induction of apoptosis. Dephosphorylation of the La protein was observed after induction of apoptosis by several initiators and in various cell types...
October 1999: Cell Death and Differentiation
M V Sitkovsky
T cells are important effector cells in natural antiviral and anticancer immunity. It is important to reveal the cellular and molecular requirements for T cell differentiation and effector functions. We explored the idea that the final outcome of antigen receptor-driven immune processes is at least partially determined by physiologically abundant small signaling molecules in extracellular environment of lymphocytes in different tissues. Extracellular purines (ATP and adenosine) and their (purinergic) receptors were studied as an example of such molecules...
October 1998: Nihon Ika Daigaku Zasshi
T Zhu, S Matsuzawa, Y Mizuno, K Kikuchi
Activities of protein phosphatases PP1 and PP2A were determined in T and B lymphocytes of autoimmune-prone MRL/MpJ-lpr/lpr mice (MRL/lpr mice) and two control strains, MRL/MpJ-(+)/+ mice (MRL/+/+ mice) and C3H/HeJ mice. Potential PP1 activity, which was measured after treatment of cell extract with Co(2+)-trypsin, was much higher in T lymphocytes than B lymphocytes. However, no difference in the activity was observed between MRL/lpr mice and the controls. Spontaneous PP2A activity showed similar levels in T and B lymphocytes from normal mice, but potential PP2A activity, which was measured after treatment with 2-mercaptoethanol, was significantly higher in T lymphocytes from MRL/lpr mice than those from controls...
July 1993: Journal of Biochemistry
S Metcalfe, J Milner
An understanding of the progressive events required for lymphocyte activation is a prerequisite to understanding the molecular mechanism of immunosuppressive reagents, and is of central relevance to autoimmunity and immune tolerance. Although reversible phosphorylation is a major control mechanism in T cell activation, few facts are known about phosphatases in T cells. It has recently become possible to block selectively the serine/threonine specific protein phosphatases PP1 and PP2A by okadaic acid, a C38 polyether fatty acid produced by dinoflagellates...
November 1990: Immunology Letters
S Matsuzawa, T Tamura, Y Mizuno, S Kobayashi, H Okuyama, Y Tsukitani, D Uemura, K Kikuchi
The differential assay conditions for protein phosphatases PP1, PP2A, and PP2C were extensively studied by using crude extracts from mouse lymphoid tissues as enzyme sources. Under these conditions, the protein phosphatase activities were measured in MRL/MpJ-lpr/lpr mice (MRL/lpr mice), autoimmune-prone mice, and MRL/MpJ(-)+/+ mice (MRL/+/+ mice) and C3H/HeJ mice as the controls. In MRL/lpr mice, significant alterations in protein phosphatase activities from those in the control mice were demonstrated. In spleen and liver from MRL/lpr mice, potential activities of PP1 and PP2A were distinctly elevated over those of the control mice...
April 1992: Journal of Biochemistry
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