Katja K?tter، نويسنده , , Shenchu Jin، نويسنده , , Christoph von Eichel-Streiber، نويسنده , , Jong-Bae Park، نويسنده , , Sung Ho Ryu، نويسنده , , Jochen Klein، نويسنده ,

1601602

Activation of astroglial phospholipase D activity by phorbol ester involves ARF and Rho proteins

12229

Primary cultures of rat cortical astrocytes express phospholipase D (PLD) isoforms 1 and 2 as determined by RT-PCR and Western blot. Basal PLD activity was strongly (10-fold) increased by 4β-phorbol-12β,13α-dibutyrate (PDB) (EC50: 56 nM), an effect which was inhibited by Ro 31-8220 (0.1–1 μM), an inhibitor of protein kinase C (PKC), and by brefeldin A (10–100 μg/ml), an inhibitor of ADP-ribosylating factor (ARF) activation. Pretreatment of the cultures with Clostridium difficile toxin B-10463 (0.1–1 ng/ml), which inactivates small G proteins of the Rho family, led to a breakdown of the astroglial cytoskeleton; concomitantly, PLD activation by PDB was reduced by up to 50%. In contrast, inactivation of proteins of the Ras family by Clostridium sordellii lethal toxin 1522 did not affect PLD activation. In parallel experiments, serum-induced PLD activation was sensitive to brefeldin A, but not to Ro 31-8220 and not to clostridial toxins. We conclude that, in astrocytes, the PLD isoform which is activated by phorbol ester requires PKC, ARF and Rho proteins for full activity and probably represents PLD1.

153

Clostridium sordellii lethal toxin , Rho protein , phospholipase D , ARF protein , Astrocyte , protein kinase C , Phorbol ester , Clostridium di¤cile toxin B

Studia Iranica

162

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