Study of Protein Phosphatase 2A (PP2A) Activity in  LPS-Induced Tolerance Using Fluorescence-Based  and Immunoprecipitation-Aided Methodology

Sun, Lei; Pappy, Adlai; Pham, Tiffany; Shanley, Thomas P.

doi:10.3390/biom5031284

Cited by 9 publications

(9 citation statements)

References 45 publications

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“…Protein phosphatase-2A (PP2A) is an abundant intracellular serine/threonine phosphatase with key roles in the regulation of many cellular functions including cellular proliferation and immune responses (45, 46). Inhibition of PP2A by okadaic acid resulted in increased nuclear translocation of NFκB and AP-1 and IL-1β expression in THP-1 macrophages (46).…”

Section: Discussionmentioning

confidence: 99%

Role of CD44 in Regulating TLR2 Activation of Human Macrophages and Downstream Expression of Proinflammatory Cytokines

Qadri

Almadani

Jay

et al. 2018

The Journal of Immunology

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Osteoarthritis (OA) is a low-grade chronic inflammatory joint disease. Innate immunity contributes to OA progression, mediated by TLR2 and TLR4. We evaluated the role of cluster determinant 44 (CD44), a transmembrane glycoprotein, in regulating TLR2-linked macrophage activation and resultant proinflammatory responses. TLR2 stimulation was performed on differentiated THP-1 macrophages in the presence or absence of a CD44-specific Ab or hyaluronan (HA). NF-κB nuclear translocation, IL-1 β and TNF-α gene expression, and protein concentrations were determined. Anti-CD44 Ab and HA treatments reduced NF-κB translocation, IL-1β and TNF-α expression, and production ( < 0.001). Inhibition of proinflammatory response in macrophages by HA was mediated by CD44. Protein phosphatase 2A mediated the reduction in NF-κB translocation by HA. CD44 knockdown reduced NF-κB nuclear translocation and downstream IL-1β and TNF-α protein production following TLR2 receptor stimulation ( < 0.001). murine bone marrow-derived macrophages produced higher TNF-α compared with macrophages following TLR2 stimulation ( < 0.01). HA dose-dependently inhibited TLR2-induced TNF-α production by murine bone marrow-derived macrophages ( < 0.001). OA synovial fluids (SF) stimulated TLR2 and TLR4 receptors and induced NF-κB translocation in THP-1 macrophages. Anti-CD44 Ab treatment significantly reduced macrophage activation by OA SF ( < 0.01). CD44 regulated TLR2 responses in human macrophages, whereby a reduction in CD44 levels or engagement of CD44 by its ligand (HA) or a CD44-specific Ab reduced NF-κB translocation and downstream proinflammatory cytokine production. A CD44-specific Ab reduced macrophage activation by OA SF, and CD44 is a potentially novel target in OA treatment.

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Section: Discussionmentioning

confidence: 99%

Role of CD44 in Regulating TLR2 Activation of Human Macrophages and Downstream Expression of Proinflammatory Cytokines

Qadri

Almadani

Jay

et al. 2018

The Journal of Immunology

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“…with 3% thioglycollate for four days (20) and neutrophils were obtained from peritoneal cavity after 5 hs of thioglycollate injection. At 5 hs, peritoneal neutrophils were harvested by repetitive (X3) lavaging of the peritoneal cavity with 10 ml of DPBS via an eighteen-gauge needle attached to a 10 ml syringe.…”

Section: Methodsmentioning

confidence: 99%

Myeloid-Specific Gene Deletion of Protein Phosphatase 2A Magnifies MyD88- and TRIF-Dependent Inflammation following Endotoxin Challenge

Sun

Pham

Cornell

et al. 2017

The Journal of Immunology

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Protein phosphatase 2A (PP2A) is a member of the intracellular serine/threonine (Ser/Thr) phosphatases. Innate immune cell activation triggered by pathogen-associated molecular patterns (PAMPs) is mediated by various protein kinases, and PP2A plays a counter regulatory role by deactivating these kinases. In this study, we generated a conditional knockout of the catalytic subunit of PP2A (PP2ACα). After crossing with myeloid-specific cre-expressing mice, effective gene knockout was achieved in various myeloid cells. The myeloid-specific knockout mice (lyM-PP2Afl/fl) showed higher mortality in response to both endotoxin challenge and bacterial infection. Upon LPS challenge, serum levels of TNF-α, KC, IL-6 and IL-10 were significantly increased in lyM-PP2Afl/fl mice and increased phosphorylation was observed in Mitogen Activated Protein Kinase (MAPK) pathways (p38, ERK, JNK) and the NF-κB pathway (IKKα/β, NF-κB p65) in bone marrow derived macrophages (BMDM) from knockout mice. Heightened NF-κB activation was not associated with degradation of IκB-α, instead, enhanced phosphorylation of the NF-κB p65 subunit and p38 phosphorylation-mediated TNF-α mRNA stabilization appear to contribute to the increased TNF-α expression. In addition, increased IL-10 expression appears to be due to PP2ACα knockout-induced IKKα/β hyper-activation. Microarray experiments indicated the TRIF/TRAF3 pathway was highly upregulated in LPS-treated PP2ACα knockout BMDM and knockout BMDM had elevated IFN-α/β production compared to control BMDM. Serum IFN-β levels from PP2ACα knockout mice treated with LPS was also greater than that in controls. Thus, we demonstrate that PP2A plays an important role in regulating inflammation and survival in the setting of septic insult, by targeting both MyD-88 and TRIF-dependent pathways.

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“…Finally, it is also noteworthy that PP2A inhibition, which also appears to be a universal feature in AD patients [29], may lead to exacerbated PIC production by LPS-activated APCs [136, 137]. The mechanism underpinning this phenomenon has not been fully delineated but it appears to be associated with altered levels of histone post-translational methylation leading to increased transcription of TNFA (the TNF-α gene) and a general increase in inflammatory status [137].…”

Section: Evidence Of Peripheral Inflammation and Immune Abnormalitiesmentioning

confidence: 99%

Could Alzheimer’s Disease Originate in the Periphery and If So How So?

et al. 2018

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The classical amyloid cascade model for Alzheimer's disease (AD) has been challenged by several findings. Here, an alternative molecular neurobiological model is proposed. It is shown that the presence of the APOE ε4 allele, altered miRNA expression and epigenetic dysregulation in the promoter region and exon 1 of TREM2, as well as ANK1 hypermethylation and altered levels of histone post-translational methylation leading to increased transcription of TNFA, could variously explain increased levels of peripheral and central inflammation found in AD. In particular, as a result of increased activity of triggering receptor expressed on myeloid cells 2 (TREM-2), the presence of the apolipoprotein E4 (ApoE4) isoform, and changes in ANK1 expression, with subsequent changes in miR-486 leading to altered levels of protein kinase B (Akt), mechanistic (previously mammalian) target of rapamycin (mTOR) and signal transducer and activator of transcription 3 (STAT3), all of which play major roles in microglial activation, proliferation and survival, there is activation of microglia, leading to the subsequent (further) production of cytokines, chemokines, nitric oxide, prostaglandins, reactive oxygen species, inducible nitric oxide synthase and cyclooxygenase-2, and other mediators of inflammation and neurotoxicity. These changes are associated with the development of amyloid and tau pathology, mitochondrial dysfunction (including impaired activity of the electron transport chain, depleted basal mitochondrial potential and oxidative damage to key tricarboxylic acid enzymes), synaptic dysfunction, altered glycogen synthase kinase-3 (GSK-3) activity, mTOR activation, impairment of autophagy, compromised ubiquitin-proteasome system, iron dyshomeostasis, changes in APP translation, amyloid plaque formation, tau hyperphosphorylation and neurofibrillary tangle formation.

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Study of Protein Phosphatase 2A (PP2A) Activity in LPS-Induced Tolerance Using Fluorescence-Based and Immunoprecipitation-Aided Methodology

Cited by 9 publications

References 45 publications

Role of CD44 in Regulating TLR2 Activation of Human Macrophages and Downstream Expression of Proinflammatory Cytokines

Role of CD44 in Regulating TLR2 Activation of Human Macrophages and Downstream Expression of Proinflammatory Cytokines

Myeloid-Specific Gene Deletion of Protein Phosphatase 2A Magnifies MyD88- and TRIF-Dependent Inflammation following Endotoxin Challenge

Could Alzheimer’s Disease Originate in the Periphery and If So How So?

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