15-Deoxy-D12,14-prostaglandin J2(15d-PGJ2), a potent endogenous ligand for peroxisome proliferators activated receptor-γ,is a cyclopentenone-type prostaglandin produced by many different types of cells. 15d-PGJ2 containing reactive α,β-unsaturated carbonyl group in the cyclopentanone ring exhibits a broad range of biological activities, including anti-proliferative and anti-inflammatory effects. HO-1 (Heme Oxygenase) catalyzes oxidative degradation of heme to biliverdin, iron, and carbon monoxide. According to recent studies, 15d-PGJ2 exerted anti-inflammatory effects through a mechanism involving HO in human lymphocytes. However, the effect of 15d-PGJ2 on HO-1 synthesis or regulation has not been elucidated yet in rVSMCs. In the present study, we examined the effects of 15d-PGJ2 on HO-1 expressions and related signal transduction mechanism in the VSMCs. Our data show that 15d-PGJ2 up-regulated both the mRNA and protein of HO-1 in a dose and time-dependent manner in rVSMCs. The GW9662, a PPAR-γ antagonist, pretreatment did not attenuate HO-1 expression. However, N-acetycystein and DTT, well known ROS inhibitors, pretreatment completely inhibited HO-1 expression. These data suggest that 15d-PGJ2 induced up-regulation of HO-1 is independent of PPARγ but dependent of ROS. The generation of ROS by 15d-PGJ2 was also confirmed by using DCFDA fluorescent probe. In addition, this 15d-PGJ2 induced HO-1 generation was blocked only by SB203580, a p38 MAP kinase inhibitor, not by Wortmannin, SP600125, and PD98059. In conclusion, our results suggest that 15d-PGJ2 up-regulates HO-1 by generating ROS in rVSMCs. Furtermore, p38 MAP kinase activation is required for 15d-PGJ2 induced HO-1 expression in rVSMCs.
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