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Regulation of thromboxane receptor signaling at multiple levels by oxidative stress-induced stabilization, relocation and enhanced responsiveness.

ABSTRACT: Thromboxane A(2) (TxA(2)) is a major, unstable arachidonic acid metabolite, and plays a key role in normal physiology and control of vascular tone. The human thromboxane receptor (TP?), expressed in COS-7 cells, is located predominantly in the endoplasmic reticulum (ER). Brief hydrogen peroxide exposure increases the efficiency of translocation of TP? from the ER into the Golgi complex, inducing maturation and stabilization of TP?. However, the ultimate fate of this post-ER TP? pool is not known, nor is its capacity to initiate signal transduction. Here we specifically assessed if functional TP? was transported to the plasma membrane following H(2)O(2) exposure.We demonstrate, by biotinylation and confocal microscopy, that exposure to H(2)O(2) results in rapid delivery of a cohort of TP? to the cell surface, which is stable for at least eight hours. Surface delivery is brefeldin A-sensitive, indicating that translocation of this receptor cohort is from internal pools and via the Golgi complex. H(2)O(2) treatment results in potentiation of the increase to intracellular calcium concentrations in response to TP? agonists U46619 and 8-iso PGF(2?) and also in the loss of ligand-dependent receptor internalization. Further there is increased responsiveness to a second application of the agonist. Finally we demonstrate that the effect of H(2)O(2) on stimulating surface delivery is shared with the FP prostanoid receptor but not the EP3 or EP4 receptors.In summary, brief exposure to H(2)O(2) results in an immediate and sustained increase in the surface pool of thromboxane receptor that is capable of mediating a persistent hyper-responsiveness of the cell and suggests a highly sophisticated mechanism for rapidly regulating thromboxane signaling.

SUBMITTER: Ball SK

PROVIDER: S-EPMC2939892 | biostudies-literature | 2010 Sep

REPOSITORIES: biostudies-literature

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Regulation of thromboxane receptor signaling at multiple levels by oxidative stress-induced stabilization, relocation and enhanced responsiveness.

Ball Stephen K SK Field Mark C MC Tippins John R JR

PloS one 20100915 9

<h4>Background</h4>Thromboxane A(2) (TxA(2)) is a major, unstable arachidonic acid metabolite, and plays a key role in normal physiology and control of vascular tone. The human thromboxane receptor (TPβ), expressed in COS-7 cells, is located predominantly in the endoplasmic reticulum (ER). Brief hydrogen peroxide exposure increases the efficiency of translocation of TPβ from the ER into the Golgi complex, inducing maturation and stabilization of TPβ. However, the ultimate fate of this post-ER TP ...[more]

PMID: 20856817

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Project description:BackgroundOxidative stress has a vital role in the early stages of vitiligo. Autoantigens released from apoptotic melanocytes (MC) under oxidative stress are involved in the presentation and recognition of antigens. However, the transport of autoantigens to the cell surface and their release to the extracellular environment are still unclear. Apoptotic bodies (ABs) have always been considered as a key source of immunomodulators and autoantigens. Yet, the role of ABs in the immune mechanism of vitiligo is still unknown.PurposeTo explore whether MC's autoantigens translocate into ABs during oxidative stress-induced apoptosis and study the molecular mechanisms underlying autoantigen migration and AB formation.MethodsPIG3V (an immortalized human vitiligo melanocyte cell line) were treated with H2O2, and ABs were separated. Transmission electron microscopy, flow cytometry, Western blot, mass spectrometry, and other methods were used to determine the relocation of specific antigens in PIG3V cells to ABs. After pretreatment with specific inhibitors (Rho kinase (Y-27632), myosin light chain kinase (MLCK, ML-9), pan-caspase (zVAD-FMK), and JNK (SP600125)), the pathway of autoantigen translocation into ABs and the formation of apoptotic bodies were determined.ResultsWhen treated with 0.8 mM H2O2, ABs were released from these cells. Autoantigens such as tyrosinase-related protein 1 (TYRP-1) and cleavage nuclear membrane antigen Lamin A/C (Asp230) were concentrated in ABs. The expression of autoantigens and the formation of ABs increased in a time- and dose-dependent manner after treatment with H2O2, while the application of specific inhibitors inhibited the formation of apoptotic bodies, i.e., the expression of antigens.ConclusionVitiligo autoantigens translocate into ABs in the process of apoptosis induced by oxidative stress. The cytoskeletal protein activation pathway and the JNK-related apoptosis pathway are involved in the transport of autoantigens and the formation of ABs. ABs may be the key bridge between MC cell apoptosis and cellular immunity.

Dataset Information

Regulation of thromboxane receptor signaling at multiple levels by oxidative stress-induced stabilization, relocation and enhanced responsiveness.

Publications

Regulation of thromboxane receptor signaling at multiple levels by oxidative stress-induced stabilization, relocation and enhanced responsiveness.

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