Oxidative stress triggers tyrosine phosphorylation in B cells through a redox‐ and inflammatory cytokine‐sensitive mechanism

Suzuki, Yoshihiro; Ohsugi, Kojune; Ono, Yasushi

doi:10.1046/j.1365-2567.1996.431546.x

Cited by 26 publications

(13 citation statements)

References 22 publications

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“…Reactive oxygen species such as hydrogen peroxide (H 2 O 2 ) activate the Akt serine/threonine kinase; however, little is known concerning the effects of oxidant treatment of cells on the regulation of PDK1, the activating kinase for Akt. Since hydrogen peroxide has been reported to stimulate tyrosine phosphorylation of signaling proteins in a number of cellular systems (3,(7)(8)(9)(10)(11)(43)(44)(45)(46)(47)(48)(49), we investigated the effects of H 2 O 2 on tyrosine phosphorylation of PDK1. Initial experiments were performed using 293T cells transiently expressing myctagged PDK1.…”

Section: Resultsmentioning

confidence: 99%

Oxidative Stress and Vanadate Induce Tyrosine Phosphorylation of Phosphoinositide-Dependent Kinase 1 (PDK1)

Prasad¹,

Topping²,

Zhou³

et al. 2000

Biochemistry

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Phosphoinositide-dependent kinase (PDK1) regulates a number of pathways involved in responses to stress and in growth factor signaling; however, little is known concerning the mechanisms governing the activity of PDK1. In this report, we find that oxidative stress (H(2)O(2)) and vanadate induce tyrosine phosphorylation of PDK1. These effects of H(2)O(2) and vanadate were found in 293T cells and CH310T1/2 cells expressing exogenous PDK1 and in A20 lymphoma cells expressing endogenous PDK1. Exogenously expressed PDK1 was also tyrosine-phosphorylated in response to NGF treatment of 293T expressing TrkA. H(2)O(2) induced a more rapid tyrosine phosphorylation of PDK1 relative to vanadate, and only vanadate-induced tyrosine phosphorylation of PDK1 was sensitive to pretreatment of cells with wortmannin. In vitro, PDK1 could be tyrosine-phosphorylated by both the c-Src and Abl tyrosine kinases. Both H(2)O(2) and vanadate treatments increased the activity of PDK1 when the serum/glucocorticoid regulated kinase (SGK) was used as substrate. Vanadate treatment appeared to bypass the requirement for phosphatidylinositol 3,4,5-trisphosphate when Akt was used as substrate for PDK1. Tyrosine phosphorylation of PDK1 by the Abl tyrosine kinase also increased the activity of PDK1 toward SGK and Akt. These data suggest a novel mechanism through which PDK1 activity may be regulated.

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Section: Resultsmentioning

confidence: 99%

Oxidative Stress and Vanadate Induce Tyrosine Phosphorylation of Phosphoinositide-Dependent Kinase 1 (PDK1)

Prasad¹,

Topping²,

Zhou³

et al. 2000

Biochemistry

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“…On the other hand, proteins that are abnormally synthesized or modified post-translationally are often targeted for ubiquitination (42,60). Since TNF␣ alters oxidant tone within cells (62), it is possible that oxidation of CCT methionine residues, or other post-synthetic modifications such as serine phosphorylation, or alterations in NH 2 -terminal protein folding could destabilize the enzyme facilitating incorporation into the ubiquitin pathway.…”

Section: Discussionmentioning

confidence: 99%

Tumor Necrosis Factor-α Inhibits Expression of CTP:Phosphocholine Cytidylyltransferase

Mallampalli¹,

Ryan²,

Salome³

et al. 2000

Journal of Biological Chemistry

114

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We investigated the effects of tumor necrosis factor ␣ (TNF␣), a key cytokine involved in inflammatory lung disease, on phosphatidylcholine (PtdCho) biosynthesis in a murine alveolar type II epithelial cell line (MLE-12). TNF␣ significantly inhibited [ 3 H]choline incorporation into PtdCho after 24 h of exposure. TNF␣ reduced the activity of CTP:phosphocholine cytidylyltransferase (CCT), the rate-regulatory enzyme within the CDP-choline pathway, by 40% compared with control, but it did not alter activities of choline kinase or cholinephosphotransferase. Immunoblotting revealed that TNF␣ inhibition of CCT activity was associated with a uniform decrease in the mass of CCT␣ in total cell lysates, cytosolic, microsomal, and nuclear subfractions of MLE cells. Northern blotting revealed no effects of the cytokine on steady-state levels of CCT␣ mRNA, and CCT␤ mRNA was not detected. Incorporation of [ 35 S]methionine into immunoprecipitable CCT␣ protein in pulse and pulsechase studies revealed that TNF␣ did not alter de novo synthesis of enzyme, but it substantially accelerated turnover of CCT␣. Addition of N-acetyl-Leu-Leu-Nle-CHO (ALLN), the calpain I inhibitor, or lactacystin, the 20 S proteasome inhibitor, blocked the inhibition of PtdCho biosynthesis mediated by TNF␣. TNF␣-induced degradation of CCT␣ protein was partially blocked by ALLN or lactacystin. CCT was ubiquitinated, and ubiquitination increased after TNF␣ exposure. m-Calpain degraded both purified CCT and CCT in cellular extracts. Thus, TNF␣ inhibits PtdCho synthesis by modulating CCT protein stability via the ubiquitin-proteasome and calpain-mediated proteolytic pathways.

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“…Since neutrophils are one of the main sources of IL10 and of IL12 (Romani et al 1997), accumulation of neutrophils may aect the determination of the balance governing Th1 and Th2 cell development at the local site. Furthermore, it was reported that neutrophil-derived oxidants possibly mediate the activation of tyrosine phosphorylation or transcriptions of in¯ammatory cytokines by releasing of the inhibitory subunit I kappa B from NF-kappa B (Suzuki et al 1996). This potentially increases the cytokine production and growth signalling pathways of T cells (Ferreira et al 1999).…”

Section: Discussionmentioning

confidence: 99%

The role of saliva of Anopheles stephensi in inflammatory response: identification of a high molecular weight neutrophil chemotactic factor

et al. 2001

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Mosquito bites can elicit dermal hypersensitivity reactions, but little is known about the chemotactic factors for host leukocytes in mosquito saliva. In this study, we determined that saliva from a malarial vector mosquito, Anopheles stephensi, possesses intense neutrophil chemotactic activity. In contrast, the midgut extract had only marginal neutrophil chemotactic activity. Eosinophil chemotactic activity was detected in the midgut but not in the saliva. According to the results of size-exclusion HPLC on a G3000SW column and Western blot analysis, the apparent molecular weight (MW) of the main neutrophil chemotactic factor (NCF) was estimated to be 200 kDa. NCF could bind with IgG from the pooled serum of Solomon islanders, whereas not with that of healthy Japanese. NCF activity was increased upon heating to 56 degrees C for 30 min or protease digestion, whereas it was affected by periodate treatment. Protease-digested NCF and naive NCF bound to lentil lectin-Sepharose, and both were eluted with a competitive sugar, methyl-alpha-D-glucoside. These results indicate that A. stephensi saliva-derived NCF is a high MW glycoprotein, and its protein moiety is important for neutrophil chemotactic activity. This NCF is thought to contribute to the inflammatory reactions through the accumulation of neutrophils at the site of the mosquito bite.

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Oxidative stress triggers tyrosine phosphorylation in B cells through a redox‐ and inflammatory cytokine‐sensitive mechanism

Cited by 26 publications

References 22 publications

Oxidative Stress and Vanadate Induce Tyrosine Phosphorylation of Phosphoinositide-Dependent Kinase 1 (PDK1)

Oxidative Stress and Vanadate Induce Tyrosine Phosphorylation of Phosphoinositide-Dependent Kinase 1 (PDK1)

Tumor Necrosis Factor-α Inhibits Expression of CTP:Phosphocholine Cytidylyltransferase

The role of saliva of Anopheles stephensi in inflammatory response: identification of a high molecular weight neutrophil chemotactic factor

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