Hwang Jinah, Lee Hyun-Il, Chang Young-Sun, Lee Soo Jae, Kim Kwang Pyo, Park Sang Ick
Division of Intractable Diseases, Center for Biomedical Sciences, National Institute of Health, Seoul, Republic of Korea.
Biochem Biophys Res Commun. 2007 May 25;357(1):206-11. doi: 10.1016/j.bbrc.2007.03.127. Epub 2007 Mar 30.
A natural ligand of peroxisome proliferator-activated receptor gamma (PPARgamma), 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)), decreases endothelial nitric oxide synthase (eNOS) expression by an unknown mechanism. Here we found that 15d-PGJ(2)-induced eNOS reduction is inversely associated with heat shock protein 70 (HSP70) induction in endothelial cells. Treatment of cells with 15d-PGJ(2) decreased eNOS protein expression in a concentration- and time-dependent manner, but independently of PPARgamma with no effect on mRNA levels. Although 15d-PGJ(2) elicited endothelial apoptosis, inhibition of both pan-caspases and cathepsins failed to reverse reduction of eNOS protein. Interestingly, we observed that 15d-PGJ(2) induced HSP70 in a dose-dependent manner. Immunoprecipitation and heat shock treatment demonstrated that eNOS reduction was strongly related to HSP70 induction. Cellular fractionation revealed that treatment with 15d-PGJ(2) increased eNOS distribution 2.5-fold from soluble to insoluble fractions. These findings provide new insights into mechanisms whereby eNOS regulation by 15d-PGJ(2) is related to HSP70 induction.
过氧化物酶体增殖物激活受体γ（PPARγ）的天然配体15-脱氧-Δ12,14-前列腺素J2（15d-PGJ2）通过未知机制降低内皮型一氧化氮合酶（eNOS）的表达。在此我们发现，15d-PGJ2诱导的eNOS减少与内皮细胞中热休克蛋白70（HSP70）的诱导呈负相关。用15d-PGJ2处理细胞以浓度和时间依赖性方式降低eNOS蛋白表达，但不依赖于PPARγ，且对mRNA水平无影响。尽管15d-PGJ2引发内皮细胞凋亡，但抑制泛半胱天冬酶和组织蛋白酶均未能逆转eNOS蛋白的减少。有趣的是，我们观察到15d-PGJ2以剂量依赖性方式诱导HSP70。免疫沉淀和热休克处理表明，eNOS减少与HSP70诱导密切相关。细胞分级分离显示，用15d-PGJ2处理使eNOS从可溶性部分到不溶性部分的分布增加了2.5倍。这些发现为15d-PGJ2对eNOS的调节与HSP70诱导相关的机制提供了新的见解。
