scholarly journals Protein phosphatase 2A activation attenuates inflammation in murine models of acute lung injury

2016 ◽  
Vol 311 (5) ◽  
pp. L903-L912 ◽  
Author(s):  
Walker M. McHugh ◽  
William W. Russell ◽  
Andrew J. Fleszar ◽  
Paul E. Rodenhouse ◽  
Skyler P. Rietberg ◽  
...  
Keyword(s):  
Lung Injury ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Neutrophil Infiltration ◽  
Neutrophil Recruitment ◽  
Bacterial Challenge ◽  
Chemokine Production ◽  
Pp2a Activity ◽  
Phosphatase 2A ◽  
The Impact

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. Previously, our laboratory employed an in vitro model to show that inhibition of PP2A results in an increase in IL-8 production in human alveolar epithelial cells. The objective of this study was to determine whether PP2A regulated this response in vivo by investigating the impact of pharmacologic activation of PP2A on chemokine production and activation of the MAPK cascade and lung injury using endotoxin- and bacterial-challenge models of ARDS in mice. N6-cyclopentyladenosine ( N6-CPA) increased PP2A activity and inhibited endotoxin-induced cytokine production in a murine alveolar macrophage cell line. N6-CPA pretreatment in mice challenged with intratracheal endotoxin decreased chemokine production, reduced neutrophil infiltration, and attenuated lung injury. Following initiation of lung injury with live Pseudomonas aeruginosa, mice that received N6-CPA 4 h following bacterial challenge showed attenuated chemokine production and reduced neutrophil infiltration compared with control mice. Pharmacologic PP2A activation both limited and prevented inflammation and tissue injury in two direct injury models of ARDS. These results suggest modulation of PP2A activity as a therapeutic target in ARDS.

Geranylgeranyl transferase regulates CXC chemokine formation in alveolar macrophages and neutrophil recruitment in septic lung injury

2013 ◽  
Vol 304 (4) ◽  
pp. L221-L229 ◽  
Author(s):  
Zirak Hasan ◽  
Milladur Rahman ◽  
Karzan Palani ◽  
Ingvar Syk ◽  
Bengt Jeppsson ◽  
...  
Keyword(s):  
Lung Injury ◽  
Alveolar Macrophages ◽  
Neutrophil Infiltration ◽  
Abdominal Sepsis ◽  
Neutrophil Recruitment ◽  
Chemokine Production ◽  
Tnf Α ◽  
Cxc Chemokine ◽  
Geranylgeranyl Transferase

Overwhelming accumulation of neutrophils is a significant component in septic lung damage, although the signaling mechanisms behind neutrophil infiltration in the lung remain elusive. In the present study, we hypothesized that geranylgeranylation might regulate the inflammatory response in abdominal sepsis. Male C57BL/6 mice received the geranylgeranyl transferase inhibitor, GGTI-2133, before cecal ligation and puncture (CLP). Bronchoalveolar lavage fluid and lung tissue were harvested for analysis of neutrophil infiltration, as well as edema and CXC chemokine formation. Blood was collected for analysis of Mac-1 on neutrophils and CD40L on platelets. Gene expression of CXC chemokines, tumor necrosis factor-α (TNF-α), and CCL2 chemokine was determined by quantitative RT-PCR in isolated alveolar macrophages. Administration of GGTI-2133 markedly decreased CLP-induced infiltration of neutrophils, edema, and tissue injury in the lung. CLP triggered clear-cut upregulation of Mac-1 on neutrophils. Inhibition of geranylgeranyl transferase reduced CLP-evoked upregulation of Mac-1 on neutrophils in vivo but had no effect on chemokine-induced expression of Mac-1 on isolated neutrophils in vitro. Notably, GGTI-2133 abolished CLP-induced formation of CXC chemokines, TNF-α, and CCL2 in alveolar macrophages in the lung. Geranylgeranyl transferase inhibition had no effect on sepsis-induced platelet shedding of CD40L. In addition, inhibition of geranylgeranyl transferase markedly decreased CXC chemokine-triggered neutrophil chemotaxis in vitro. Taken together, our findings suggest that geranylgeranyl transferase is an important regulator of CXC chemokine production and neutrophil recruitment in the lung. We conclude that inhibition of geranylgeranyl transferase might be a potent way to attenuate acute lung injury in abdominal sepsis.

Abstract 229: Novel Plasma Membrane Beta Adrenergic Receptor Resensitization By Protein Phosphatase 2a

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Neelakantan T Vasudevan ◽  
Anita Shukla ◽  
Sathyamangla V Naga Prasad
Keyword(s):  
Plasma Membrane ◽  
Protein Phosphatase ◽  
Adrenergic Receptor ◽  
Protein Phosphatase 2A ◽  
Metabolic Labeling ◽  
Specific Expression ◽  
Pp2a Activity ◽  
Pi3k Activity ◽  
Phosphatase 2A

Resensitization of β-adrenergic receptor (βAR) occurs by dephosphorylation of the internalized βAR by protein phosphatase 2A (PP2A) before being recycled back to plasma membrane (PM). Contrary to this classical paradigm, cardiac specific expression of inactive PI3Kγ (PI3Kγ inact ) leads to receptor resensitization at the plasma membrane as measured by adenylyl cyclase activity in mice chronically treated with the agonist. We hypothesized that PI3K activity inhibits PM receptor resensitization. Using cells stably expressing FLAG-β 1 AR alone (single) or along with PI3Kγ inact (double), we show that inhibition of PI3K activity results in novel PM receptor resensitization. Agonist activation of single stables showed significant receptor desensitization as measured by reduced cAMP generation (35.6 ± 4.6 pmol/mg protein). In contrast, double-or wortmannin (Wort, PI3K inhibitor) pre-treated single- stables showed marked generation of cAMP (87.4 ± 3.2 or 83.1 ± 5.7) showing β 1 AR resensitization. Agonist stimulation of metabolically labeled β 1 ARs pre-treated with inhibitors of internalization, sucrose and β-cyclodextrin resulted in accumulation of phosphorylated receptors at the PM, which was abolished with PI3Kγ inact suggesting dephosphorylation of β 1 ARs. Inhibition of PP2A by okadaic acid or Fostriecin resulted in complete loss of β 1 AR resensitization despite the presence of PI3Kγ inact showing that PI3K regulates PP2A activity at the β 1 AR complex. Pre-treatment of single stable cells with Wort resulted in significant increase in β 1 AR-associated phosphatase activity following dobutamine (Dob) treatment (Veh, 4131 ± 14; Dob, 3180 ± 111; Dob + Wort, 17123 ± 680 pmoles/mg protein). Consistently, similar results were obtained in vivo using single transgenic (FLAG-β 1 AR, Veh, 87 ± 12; Dob, 61.7 ± 8.3) and double transgenic (FLAG-β 1 AR and PI3Kγ inact , Veh, 93 ± 9; Dob, 118 ± 6) mice. In vivo metabolic labeling, co-immunoprecipitation and in vitro kinase assays showed that inhibitor of PP2A (I2PP2A) protein as a target of PI3K in regulating PP2A activity at the β 1 AR complex. Indeed, siRNA knock down of I2PP2A results in preservation of β 1 AR function by PM receptor resensitization demonstrating a novel role for PI3K in receptor resensitization. This research has received full or partial funding support from the American Heart Association, AHA Great Rivers Affiliate (Delaware, Kentucky, Ohio, Pennsylvania & West Virginia).

scholarly journals B56-Associated Protein Phosphatase 2A Is Required For Survival and Protects from Apoptosis in Drosophila melanogaster

2002 ◽  
Vol 22 (11) ◽  
pp. 3674-3684 ◽  
Author(s):  
Xinghai Li ◽  
Anne Scuderi ◽  
Anthea Letsou ◽  
David M. Virshup
Keyword(s):  
Cell Death ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Specific Protein ◽  
S2 Cells ◽  
Regulatory Subunits ◽  
Pp2a Activity ◽  
Phosphatase 2A

ABSTRACT Protein phosphorylation and specific protein kinases can initiate signal transduction pathways leading to programmed cell death. The specific protein phosphatases regulating apoptosis have been more elusive. Using double-stranded RNA-mediated interference (RNAi), the role of protein phosphatase 2A (PP2A) in cellular signaling was investigated. Knockdown of A or C subunits individually or of combined B subunits led to concurrent loss of nontargeted PP2A subunits, suggesting that PP2A is an obligate heterotrimer in vivo. Global knockdown of PP2A activity or specific loss of redundant B56 regulatory subunits caused cell death with the morphological and biochemical changes characteristic of apoptosis in cultured S2 cells. B56:PP2A-regulated apoptosis required caspases and the upstream regulators dark, reaper, head involution defective, and dp53. In Drosophila embryos, knockdown of B56-regulated PP2A activity resulted in apoptosis and failure of gastrulation, an effect that was blocked by concurrent RNAi of the caspase Drice. B56-regulated PP2A activity appears to be required upstream of dp53 to maintain a critical proapoptotic substrate in a dephosphorylated, inactive state, thereby preventing apoptosis in Drosophila S2 cells.

scholarly journals beta-blocker reverses inhibition of beta-2 adrenergic receptor resensitization by hypoxia

2020 ◽  
Author(s):  
Yu Sun ◽  
Manveen K. Gupta ◽  
Kate Stenson ◽  
Maradumane L. Mohan ◽  
Nicholas Wanner ◽  
...  
Keyword(s):  
Heart Failure ◽  
Protein Phosphatase ◽  
Adrenergic Receptor ◽  
Protein Phosphatase 2A ◽  
Receptor Internalization ◽  
Pp2a Activity ◽  
Phosphatase 2A ◽  
Β Blocker ◽  
Underlying Mechanisms

AbstractIschemia/hypoxia is major underlying cause for heart failure and stroke. Although beta-adrenergic receptor (βAR) is phosphorylated in response to hypoxia, less is known about the underlying mechanisms. Hypoxia results in robust GRK2-mediated β2AR phosphorylation but does not cause receptor internalization. However, hypoxia leads to significant endosomal-β2AR phosphorylation accompanied by inhibition of β2AR-associated protein phosphatase 2A (PP2A) activity impairing resensitization. Phosphoinositide 3-kinase γ (PI3Kγ) impedes resensitization by phosphorylating endogenous inhibitor of protein phosphatase 2A, I2PP2A that inhibits PP2A activity. Hypoxia increased PI3Kγ activity leading to significant phosphorylation of I2PP2A resulting in inhibition of PP2A and consequently resensitization. Surprisingly, β-blocker abrogated hypoxia-mediated β2AR phosphorylation instead of phosphorylation in normoxia. Subjecting mice to hypoxia leads to significant cardiac dysfunction and β2AR phosphorylation showing conservation of non-canonical hypoxia-mediated pathway in vivo. These findings provide mechanistic insights on hypoxia-mediated βAR dysfunction which is rescued by β-blocker and will have significant implications in heart failure and stroke.

Protein Phosphatase 2A Affects the Symptoms of Depressive Rats by Regulating Extracellular Signal-regulated Kinases/Glycogen Synthase Kinase 3β Signaling Pathway

2019 ◽  
Vol 9 (5) ◽  
pp. 592-598
Author(s):  
Guangshan Zheng ◽  
Zhenzhen Chen ◽  
Longjian Huang ◽  
Jianmin Huang ◽  
Yan Li ◽  
...  
Keyword(s):  
Protein Phosphatase ◽  
Common Mental Disorders ◽  
Glycogen Synthase ◽  
Protein Phosphatase 2A ◽  
Antidepressant Drugs ◽  
Morris Water Maze Test ◽  
Model Group ◽  
Expression Levels ◽  
Pp2a Activity ◽  
Phosphatase 2A

As one of the world's more common mental disorders, the incidence of depression has increased yearly, seriously affecting the lives and health of many people. Protein phosphatase 2A (PP2A) is a protein that is enriched in the brain tissue, is the major serine/threonine phosphatase in the central nervous system, and plays a very important role in many aspects of cellular function. To explore the role of PP2A in the pathogenesis of depression in our study, we constructed the depressive disorder model, which involves the exposure of Sprague Dawley rats to chronic unpredictable stress (CUS). The rats with depression were then treated with different concentrations (low, moderate, high) of okadaic acid (OA), and the optimal OA concentration (OOA) for the follow-up study was selected based on PP2A activity. The results showed that the use of higher OA concentrations corresponded with stronger inhibition of PP2A activity. Moreover, the behavioral test performed on the depression model rats showed that OOA group exhibited significant improvements in weight, as well as in their results in the sucrose preference test, open-field test, and Morris water maze test compared to the model group (P < 0.05). Moreover, when compared with the model group, the amounts of NE and 5-HT increased significantly (P < 0.05), and the expression levels of TH, ERK1, AKT1, as well as the phosphorylation of TH, ERK1, AKT1, and GSK-3β, were observed to be increased in the OOA group (P < 0.05). Furthermore, the content of CORT decreased significantly (P < 0.05), and the expression levels of GSK-3β were decreased in the OOA group (P < 0.05). Thus, the potential mechanism of how OA ameliorates depression in model rats may be through the inhibition of PP2A activity, the increase in phosphorylation levels of AKT and GSK-3β, and through the PP2A/AKT/GSK-3β signal pathway; these components may serve as important intracellular targets for antidepressant drugs.

scholarly journals Progesterone decreases tyrosine hydroxylase phosphorylation state and increases protein phosphatase 2A activity in the stalk-median eminence on proestrous afternoon

2009 ◽  
Vol 204 (2) ◽  
pp. 209-219 ◽  
Author(s):  
Bin Liu ◽  
Lydia A Arbogast
Keyword(s):  
Tyrosine Hydroxylase ◽  
Median Eminence ◽  
Protein Phosphatase ◽  
Time Course ◽  
Protein Phosphatase 2A ◽  
Plasma Prolactin ◽  
Phosphorylation State ◽  
Pp2a Activity ◽  
Phosphatase 2A ◽  
Camp Levels

The progesterone (P4) rise on proestrous afternoon is associated with dephosphorylation of tyrosine hydroxylase (TH) and reduced TH activity in the stalk-median eminence (SME), which contributes to the proestrous prolactin surge in rats. In the present study, we investigated the time course for P4 effect on TH activity and phosphorylation state, as well as cAMP levels and protein phosphatase 2A (PP2A) activity and quantity, in the SME on proestrous morning and afternoon. P4 (7.5 mg/kg, s.c.) treatment on proestrous afternoon decreased TH activity and TH phosphorylation state at Ser-31 and Ser-40 within 1 h, whereas morning administration of P4 had no 1 h effect on TH. PP2A activity in the SME was enhanced after P4 treatment for 1 h on proestrous afternoon without a change in PP2A catalytic subunit quantity, whereas P4 treatment had no effect on PP2A activity or quantity on proestrous morning. cAMP levels in the SME were unchanged with 1 h P4 treatment. At 5 h after P4 treatment, TH activity and phosphorylation state declined coincident with an increase in plasma prolactin in both P4-treated morning and afternoon groups. PP2A activity in the SME was unchanged in 5 h P4-treated rat. Our data suggest that P4 action on tuberoinfundibular dopaminergic (TIDA) neurons involves at least two components. A more rapid (1 h) P4 effect engaged only on proestrous afternoon likely involves the activation of PP2A. The longer P4 action on TIDA neurons is evident on both the morning and afternoon of proestrus and may involve a common, as yet unidentified, mechanism.

scholarly journals Loss of myeloid-specific protein phosphatase 2A enhances lung injury and fibrosis and results in IL-10-dependent sensitization of epithelial cell apoptosis

2019 ◽  
Vol 316 (6) ◽  
pp. L1035-L1048 ◽  
Author(s):  
Lei Sun ◽  
Elissa M. Hult ◽  
Timothy T. Cornell ◽  
Kevin K. Kim ◽  
Thomas P. Shanley ◽  
...  
Keyword(s):  
Epithelial Cell ◽  
Epithelial Cells ◽  
Lung Injury ◽  
Protein Phosphatase ◽  
Cell Apoptosis ◽  
Cell Function ◽  
Protein Phosphatase 2A ◽  
Cytokine Signaling ◽  
Epithelial Cell Apoptosis ◽  
Phosphatase 2A

Protein phosphatase 2A (PP2A), a ubiquitously expressed Ser/Thr phosphatase is an important regulator of cytokine signaling and cell function. We previously showed that myeloid-specific deletion of PP2A (LysMcrePP2A−/−) increased mortality in a murine peritoneal sepsis model. In the current study, we assessed the role of myeloid PP2A in regulation of lung injury induced by lipopolysaccharide (LPS) or bleomycin delivered intratracheally. LysMcrePP2A−/− mice experienced increased lung injury in response to both LPS and bleomycin. LysMcrePP2A−/− mice developed more exuberant fibrosis in response to bleomycin, elevated cytokine responses, and chronic myeloid inflammation. Bone marrow-derived macrophages (BMDMs) from LysMcrePP2A−/− mice showed exaggerated inflammatory cytokine release under conditions of both M1 and M2 activation. Notably, secretion of IL-10 was elevated under all stimulation conditions, including activation of BMDMs by multiple Toll-like receptor ligands. Supernatants collected from LPS-stimulated LysMcrePP2A−/− BMDMs induced epithelial cell apoptosis in vitro but this effect was mitigated when IL-10 was also depleted from the BMDMs by crossing LysMcrePP2A−/− mice with systemic IL-10−/− mice (LysMcrePP2A−/− × IL-10−/−) or when IL-10 was neutralized. Despite these findings, IL-10 did not directly induce epithelial cell apoptosis but sensitized epithelial cells to other mediators from the BMDMs. Taken together our results demonstrate that myeloid PP2A regulates production of multiple cytokines but that its effect is most pronounced on IL-10 production. Furthermore, IL-10 sensitizes epithelial cells to apoptosis in response to myeloid-derived mediators, which likely contributes to the pathogenesis of lung injury and fibrosis in this model.

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