Ig Receptor Binding Protein 1 (α4) Is Associated With a Rapamycin-Sensitive Signal Transduction in Lymphocytes Through Direct Binding to the Catalytic Subunit of Protein Phosphatase 2A

Blood ◽  
1998 ◽  
Vol 92 (2) ◽  
pp. 539-546
Author(s):  
Seiji Inui ◽  
Hideki Sanjo ◽  
Kazuhiko Maeda ◽  
Hideyuki Yamamoto ◽  
Eishichi Miyamoto ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Inhibitory Effect ◽  
Catalytic Subunit ◽  
Jurkat Cells ◽  
Vitro Assay ◽  
Rapamycin Treatment ◽  
Phosphatase 2A

Rapamycin is an immunosuppressant that effectively controls various immune responses; however, its action in the signal transduction of lymphocytes has remained largely unknown. We show here that a phosphoprotein encoded by mouse α4 (mα4) gene transmitting a signal through B-cell antigen receptor (BCR) is associated with the catalytic subunit of protein phosphatase 2A (PP2Ac). The middle region of α4, consisting of 109 amino acids (94-202), associates directly with PP2Ac, irrespective of any other accessory molecule. Rapamycin treatment disrupts the association of PP2Ac/α4 in parallel with the inhibitory effect of lymphoid cell proliferation. The effect of rapamycin was inhibited with an excess amount of FK506 that potentially completes the binding to FKBP. Rapamycin treatment also suppresses the phosphatase activity of cells measured by in vitro phosphatase assay. Introduction of the mα4 cDNA into Jurkat cells or the increased association of PP2Ac/α4 by the culture with low serum concentration confers cells with rapamycin resistance. Moreover, glutathione S-transferase (GST)-α4 augments the PP2A activity upon myelin basic protein (MBP) and histone in the in vitro assay. These results suggest that α4 acts as a positive regulator of PP2A and as a new target of rapamycin in the activation of lymphocytes.

Ig Receptor Binding Protein 1 (α4) Is Associated With a Rapamycin-Sensitive Signal Transduction in Lymphocytes Through Direct Binding to the Catalytic Subunit of Protein Phosphatase 2A

Blood ◽  
1998 ◽  
Vol 92 (2) ◽  
pp. 539-546 ◽  
Author(s):  
Seiji Inui ◽  
Hideki Sanjo ◽  
Kazuhiko Maeda ◽  
Hideyuki Yamamoto ◽  
Eishichi Miyamoto ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Inhibitory Effect ◽  
Catalytic Subunit ◽  
Jurkat Cells ◽  
Vitro Assay ◽  
Rapamycin Treatment ◽  
Phosphatase 2A

Abstract Rapamycin is an immunosuppressant that effectively controls various immune responses; however, its action in the signal transduction of lymphocytes has remained largely unknown. We show here that a phosphoprotein encoded by mouse α4 (mα4) gene transmitting a signal through B-cell antigen receptor (BCR) is associated with the catalytic subunit of protein phosphatase 2A (PP2Ac). The middle region of α4, consisting of 109 amino acids (94-202), associates directly with PP2Ac, irrespective of any other accessory molecule. Rapamycin treatment disrupts the association of PP2Ac/α4 in parallel with the inhibitory effect of lymphoid cell proliferation. The effect of rapamycin was inhibited with an excess amount of FK506 that potentially completes the binding to FKBP. Rapamycin treatment also suppresses the phosphatase activity of cells measured by in vitro phosphatase assay. Introduction of the mα4 cDNA into Jurkat cells or the increased association of PP2Ac/α4 by the culture with low serum concentration confers cells with rapamycin resistance. Moreover, glutathione S-transferase (GST)-α4 augments the PP2A activity upon myelin basic protein (MBP) and histone in the in vitro assay. These results suggest that α4 acts as a positive regulator of PP2A and as a new target of rapamycin in the activation of lymphocytes.

scholarly journals Acute regulation of renal Na+/H+ exchanger NHE3 by dopamine: role of protein phosphatase 2A

2010 ◽  
Vol 298 (5) ◽  
pp. F1205-F1213 ◽  
Author(s):  
I. Alexandru Bobulescu ◽  
Henry Quiñones ◽  
Serge M. Gisler ◽  
Francesca Di Sole ◽  
Ming-Chang Hu ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Okadaic Acid ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Simian Virus 40 ◽  
Receptor Activation ◽  
T Antigen ◽  
Phosphatase 2A

Nephrogenic dopamine is a potent natriuretic paracrine/autocrine hormone that is central for mammalian sodium homeostasis. In the renal proximal tubule, dopamine induces natriuresis partly via inhibition of the sodium/proton exchanger NHE3. The signal transduction pathways and mechanisms by which dopamine inhibits NHE3 are complex and incompletely understood. This manuscript describes the role of the serine/threonine protein phosphatase 2A (PP2A) in the regulation of NHE3 by dopamine. The PP2A regulatory subunit B56δ (coded by the Ppp2r5d gene) directly associates with more than one region of the carboxy-terminal hydrophilic putative cytoplasmic domain of NHE3 (NHE3-cyto), as demonstrated by yeast-two-hybrid, coimmunoprecipitation, blot overlay, and in vitro pull-down assays. Phosphorylated NHE3-cyto is a substrate for purified PP2A in an in vitro dephosphorylation reaction. In cultured renal cells, inhibition of PP2A by either okadaic acid or by overexpression of the simian virus 40 (SV40) small T antigen blocks the ability of dopamine to inhibit NHE3 activity and to reduce surface NHE3 protein. Dopamine-induced NHE3 redistribution is also blocked by okadaic acid ex vivo in rat kidney cortical slices. These studies demonstrate that PP2A is an integral and critical participant in the signal transduction pathway between dopamine receptor activation and NHE3 inhibition.

scholarly journals Developmental Expression of Protein Phosphatase 2A in the Kidney

1999 ◽  
Vol 10 (8) ◽  
pp. 1737-1745
Author(s):  
ALLEN D. EVERETT ◽  
CHUN XUE ◽  
TAMARA STOOPS
Keyword(s):  
Signal Transduction ◽  
Protein Phosphatase ◽  
Kidney Development ◽  
Developmental Regulation ◽  
Protein Phosphatase 2A ◽  
Catalytic Subunit ◽  
Developmental Expression ◽  
Regulatory Subunit ◽  
Northern Analysis ◽  
Phosphatase 2A

Abstract. Although a number of growth and transcription factors are known to regulate renal growth and development, the signal transduction molecules necessary to mediate these developmental signals are relatively unknown. Therefore, the activity and mRNA and protein expression of the signal transduction molecule protein phosphatase 2A (PP2A) were examined during rat kidney development. Northern analysis of total kidney RNA or Western analysis of kidney protein homogenates from embryonic day 15 to 90-d-old adults demonstrated developmental regulation of the catalytic, major 55-kD B regulatory subunit and A structural subunit with the highest levels of expression in late embryonic and newborn kidneys. Similarly, okadaic acid-inhibitable phosphatase enzyme activity was highest in the embryonic and newborn kidney. To map cell-specific expression of PP2A in the developing kidney, in situ hybridization with a catalytic subunit digoxigenin-labeled cRNA was performed on embryonic day 20 and newborn kidneys. PP2A was found predominately in the nephrogenic cortex and particularly in the developing glomeruli and nonbrush border tubules in the embryonic day 20 and newborn kidneys. Similarly, immunocytochemistry with a specific PP2A catalytic subunit polyclonal anti-peptide antibody demonstrated catalytic subunit protein particularly concentrated in the podocytes of glomeruli in the newborn kidney. In the adult kidney, PP2A protein was no longer detectable except in the nuclei of distal tubular cells. Therefore, the developmental regulation of PP2A activity and protein during kidney development and its mapping to the nephrogenic cortex, developing glomeruli, and tubules suggests a role for PP2A in the regulation of nephron growth and differentiation.

scholarly journals The catalytic subunit of protein phosphatase 2A is carboxyl-methylated in vivo.

1994 ◽  
Vol 269 (23) ◽  
pp. 16311-16317 ◽  
Author(s):  
B. Favre ◽  
S. Zolnierowicz ◽  
P. Turowski ◽  
B.A. Hemmings
Keyword(s):  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Catalytic Subunit ◽  
Phosphatase 2A

scholarly journals IMMU-47. PROTEIN PHOSPHATASE 2A INHIBITION IN NK CELL THERAPY FOR TREATMENT OF MEDULLOBLASTOMA

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii115-ii115
Author(s):  
Rongze Olivia Lu ◽  
Winson Ho ◽  
Brandon Chiou
Keyword(s):  
Nk Cells ◽  
Cell Line ◽  
Protein Phosphatase ◽  
Nk Cell ◽  
Protein Phosphatase 2A ◽  
T Cell Response ◽  
Intrinsic Activity ◽  
Cd107a Expression ◽  
Phosphatase 2A

Abstract Checkpoint immunotherapy (ICB) thus far has shown limited efficacy against brain tumors, such as medulloblastoma (MB). Its low mutational burden is thought to result in a paucity of neoantigen to trigger an effective T-cell response. Natural killer (NK) cells, can recognize tumor cells independently of neoantigens, making them appealing against MBs. Modulation of NK cells to enhance cytotoxicity against MBs could be a novel treatment strategy. Protein Phosphatase 2A (PP2A), a ubiquitous serine/threonine phosphatase, has been shown to inhibit IFNg and Granzyme B production by NK cells. We hypothesize that NK92, a transformed human NK cell line, has intrinsic activity against human MB cells and that inhibiting PP2A pharmacologically can enhance cytotoxicity of NK92 cells. We performed NK cytotoxicity assay and granulation assay against human MB cell line D425. We also used a small molecular inhibitor, LB100, to modulate PP2A activity in NK92. NK92 cells were co-cultured with D425, in increasing E:T (Effector:Target) ratio for 4 hours. D425 cells were pre-labeled with CellTrace Violet dye. The percentage of D425 (Violet+) cells in apoptosis (Cas3/7+) or necrosis (AAD+) were compared with different ET ratios to quantify NK mediated cell cytotoxicity. We also measured CD107a expression in NK92 to assess granulation with LB100 treatment. D425 cells were sensitive to NK92 killing. Percentage of D425 cells either apoptotic or necrotic increased with increasing ET ratio, suggesting that there was NK92 mediated cytotoxicity. Percentage of killed D425 cells ranged from 18% at baseline (without NK92) to 80% at ET ratio of 20. Inhibition of PP2A using LB100, enhanced NK92 degranulation. CD107a+ NK92 cells increased from 19% to 28% with 8uM of LB100. NK92 cells are cytotoxic against MB cells in vitro and inhibition of PP2A in NK cells can enhance their activity against MB cells.

Structure and transcriptional regulation of protein phosphatase 2A catalytic subunit genes [Erratum to document cited in CA114(3):18572v]

Biochemistry ◽  
1991 ◽  
Vol 30 (21) ◽  
pp. 5328-5328 ◽  
Author(s):  
Yeesim Khew-Goodall ◽  
Regina E. Mayer ◽  
Francisca Maurer ◽  
Stuart R. Stone ◽  
Brian A. Hemmings
Keyword(s):  
Transcriptional Regulation ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Catalytic Subunit ◽  
Phosphatase 2A

Identification of protein phosphatase 2A as an interacting protein of leucine-rich repeat kinase 2

2016 ◽  
Vol 397 (6) ◽  
pp. 541-554 ◽  
Author(s):  
Panagiotis S. Athanasopoulos ◽  
Wright Jacob ◽  
Sebastian Neumann ◽  
Miriam Kutsch ◽  
Dirk Wolters ◽  
...  
Keyword(s):  
Hela Cells ◽  
Protein Phosphatase ◽  
Protein Phosphatase 2A ◽  
Catalytic Subunit ◽  
Sodium Selenate ◽  
Leucine Rich Repeat ◽  
Human Neuroblastoma ◽  
Interacting Protein ◽  
Cellular Degeneration ◽  
Phosphatase 2A

Abstract Mutations in the gene coding for the multi-domain protein leucine-rich repeat kinase 2 (LRRK2) are the leading cause of genetically inherited Parkinson’s disease (PD). Two of the common found mutations are the R1441C and G2019S. In this study we identified protein phosphatase 2A (PP2A) as an interacting partner of LRRK2. We were able to demonstrate that the Ras of complex protein (ROC) domain is sufficient to interact with the three subunits of PP2A in human neuroblastoma SH-SY5Y cells and in HeLa cells. The alpha subunit of PP2A is interacting with LRRK2 in the perinuclear region of HeLa cells. Silencing the catalytic subunit of PP2A by shRNA aggravated cellular degeneration induced by the pathogenic R1441C-LRRK2 mutant expressed in neuroblastoma SH-SY5Y cells. A similar enhancement of apoptotic nuclei was observed by downregulation of the catalytic subunit of PP2A in cultured cortical cells derived from neurons overexpressing the pathogenic mutant G2019S-LRRK2. Conversely, pharmacological activation of PP2A by sodium selenate showed a partial neuroprotection from R1441C-LRRK2-induced cellular degeneration. All these data suggest that PP2A is a new interacting partner of LRRK2 and reveal the importance of PP2A as a potential therapeutic target in PD.

scholarly journals A Novel Interaction of the Catalytic Subunit of Protein Phosphatase 2A with the Adaptor Protein CIN85 Suppresses Phosphatase Activity and Facilitates Platelet Outside-in αIIbβ3 Integrin Signaling

2016 ◽  
Vol 291 (33) ◽  
pp. 17360-17368 ◽  
Author(s):  
Tanvir Khatlani ◽  
Subhashree Pradhan ◽  
Qi Da ◽  
Tanner Shaw ◽  
Vladimir L. Buchman ◽  
...  
Keyword(s):  
Phosphatase Activity ◽  
Protein Interactions ◽  
Protein Phosphatase ◽  
Thrombus Formation ◽  
Protein Phosphatase 2A ◽  
Adaptor Protein ◽  
Fibrin Clot ◽  
Catalytic Subunit ◽  
Clot Retraction ◽  
Phosphatase 2A

The transduction of signals generated by protein kinases and phosphatases are critical for the ability of integrin αIIbβ3 to support stable platelet adhesion and thrombus formation. Unlike kinases, it remains unclear how serine/threonine phosphatases engage the signaling networks that are initiated following integrin ligation. Because protein-protein interactions form the backbone of signal transduction, we searched for proteins that interact with the catalytic subunit of protein phosphatase 2A (PP2Ac). In a yeast two-hybrid study, we identified a novel interaction between PP2Ac and an adaptor protein CIN85 (Cbl-interacting protein of 85 kDa). Truncation and alanine mutagenesis studies revealed that PP2Ac binds to the P3 block (396PAIPPKKPRP405) of the proline-rich region in CIN85. The interaction of purified PP2Ac with CIN85 suppressed phosphatase activity. Human embryonal kidney 293 αIIbβ3 cells overexpressing a CIN85 P3 mutant, which cannot support PP2Ac binding, displayed decreased adhesion to immobilized fibrinogen. Platelets contain the ∼85 kDa CIN85 protein along with the PP2Ac-CIN85 complex. A myristylated cell-permeable peptide derived from residues 395–407 of CIN85 protein (P3 peptide) disrupted the platelet PP2Ac-CIN85 complex and decreased αIIbβ3 signaling dependent functions such as platelet spreading on fibrinogen and thrombin-mediated fibrin clot retraction. In a phospho-profiling study P3 peptide treated platelets also displayed decreased phosphorylation of several signaling proteins including Src and GSK3β. Taken together, these data support a role for the novel PP2Ac-CIN85 complex in supporting integrin-dependent platelet function by dampening the phosphatase activity.

Sign in / Sign up

Export Citation Format

Share Document