Laboratory of Molecular Toxicology, College of Pharmacy, Pusan National University, Busan, South Korea.
J Toxicol Environ Health A. 2010;73(21-22):1560-9. doi: 10.1080/15287394.2010.511582.
Phospholipase D (PLD) is an enzyme that catalyzes the hydrolysis of phosphatidyl choline (PC) to generate phosphatidic acid (PA) and choline. PLD is believed to play an important role in cell proliferation, survival signaling, cell transformation, and tumor progression. However, it remains to be determined whether enhanced expression of PLD in liver is sufficient to induce hepatotoxicity. The aim of this study was to investigate the possible role of PLD in di(2-ethylhexyl) phthalate (DEHP)-induced hepatotoxicity in Sprague-Dawley rats. The phthalate, DEHP (500 mg/kg/d), was administered orally, daily to prepubertal rats (4 wk of age, weighing approximately 70-90 g) for 1, 7, or 28 d. In this study, protein expression levels of PLD1/2, peroxisome proliferator-activated receptor (PPAR), and cytochrome P-450 (CYP) were determined by Western blot analysis using specific antibodies. Liver weight was significantly increased in the DEHP treatment groups. Immunohistochemical analysis demonstrated that DEHP produced strong staining of proliferating cell nuclear antigen (PCNA) at 28 d of exposure, suggestive of hepatocyte proliferation. A significant rise in PLD1/2 expression was observed in liver of DEHP-exposed rats after 7 d. Further, PPARα, constitutive androstane receptor (CAR), pregnane X receptor (PXR), and CYP2B1 protein expression levels were markedly elevated in DEHP-treated groups. Our results suggest that DEHP significantly enhanced the expression of PLD, which may be correlated with PPARα-induced hepatotoxicity through a complex interaction with nuclear receptors including CAR and PXR.
磷脂酶 D (PLD) 是一种酶，能够催化磷脂酰胆碱 (PC) 的水解，生成磷脂酸 (PA) 和胆碱。PLD 被认为在细胞增殖、存活信号、细胞转化和肿瘤进展中发挥重要作用。然而，PLD 在肝脏中的表达增强是否足以引起肝毒性仍有待确定。本研究旨在探讨 PLD 在邻苯二甲酸二(2-乙基己基)酯 (DEHP) 诱导的 Sprague-Dawley 大鼠肝毒性中的可能作用。将邻苯二甲酸二(2-乙基己基)酯 (DEHP，500mg/kg/d) 以口服方式每天给予 4 周龄（体重约 70-90g）的幼鼠，连续 1、7 或 28 天。在本研究中，使用特异性抗体通过 Western blot 分析测定 PLD1/2、过氧化物酶体增殖物激活受体 (PPAR) 和细胞色素 P-450 (CYP) 的蛋白表达水平。DEHP 处理组的肝重显著增加。免疫组织化学分析表明，DEHP 在暴露 28 天时对增殖细胞核抗原 (PCNA) 产生强烈染色，提示肝细胞增殖。在 DEHP 暴露的大鼠肝脏中，PLD1/2 的表达在 7 天后显著升高。此外，DEHP 处理组的 PPARα、组成型雄烷受体 (CAR)、孕烷 X 受体 (PXR) 和 CYP2B1 蛋白表达水平显著升高。我们的结果表明，DEHP 显著增强了 PLD 的表达，这可能与 PPARα 诱导的肝毒性通过与 CAR 和 PXR 等核受体的复杂相互作用有关。
