摘要：

We have investigated the novel function of intracellular reactive oxygen species (ROS) in the activation of in situ tissue transglutaminase (tTGase) by lysophosphatidic acid (LPA) and transforming growth factor-β (TGF-β) in Swiss 3T3 fibroblasts. LPA induced a transient increase of intracellular ROS with a maximal increase at 10 min, which was blocked by ROS scavengers, N-acetyl- l-cysteine and catalase. LPA activated tTGase with a maximal increase at 1 h, which was inhibited by cystamine and ROS scavengers. Incubation with exogenous H 2O 2 activated tTGase. TGF-β also activated tTGase with a maximal activation at 2 h and the tTGase activation was inhibited by the ROS scavengers. Scrape-loading of C3 transferase inhibited the ROS production and in situ tTGase activation by LPA and TGF-β, and the inhibitory effect of C3 transferase was reversed by exogenous H 2O 2. Microinjection of GTPγS inhibited transamidating activity of tTGase stimulated by LPA, TGF-β, and maitotoxin. These results suggested that intracellular ROS was essential for the activation of in situ tTGase in response to LPA and TGF-β.

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