Department of Metabolism and Nutrition, Instituto de Ciencia y Tecnologia de Alimentos y Nutricion (ICTAN-CSIC), José Antonio Novais 10, Ciudad Universitaria, 28040, Madrid, Spain.
Eur J Nutr. 2012 Oct;51(7):881-92. doi: 10.1007/s00394-011-0269-1. Epub 2011 Nov 1.
Procyanidin B2 (PB2) is a naturally occurring flavonoid widely found in cocoa, red wine and grape juice. Recent studies have suggested that PB2 could protect against oxidative stress- and chemical-induced injury in colonic cells by modulating the endogenous cellular defence. However, the precise mechanism for this protection is not fully understood. Herein, we examined the effect of PB2 on the expression of one of the major antioxidant/detoxificant enzymes related to intestinal protection, the glutathione S-transferase P1 (GSTP1), and the molecular mechanisms involved.
Human colonic Caco-2 cells were treated with PB2 at different times and enzymatic activity, and mRNA and protein levels of GSTP1 were evaluated. The nuclear translocation of the transcription factor NF-erythroid 2-related factor (Nrf2) and the phosphorylation states of specific proteins central to intracellular signalling cascades were also investigated.
PB2 induced the expression and activity of GSTP1 and the nuclear translocation of Nrf2. Interestingly, two important signalling proteins involved in Nrf2 translocation, the extracellular signal-regulated protein kinases (ERKs) and the p38 mitogen-activated protein kinase (MAPK) were also activated. Further experiments with specific inhibitors of both pathways confirmed their critical role in the beneficial effects induced by PB2.
The present results show that PB2 protects against oxidative injury in colonic cells and up-regulate the expression of GSTP1 via a mechanism that involves ERK and p38 MAPK activation and Nrf2 translocation. These results provide a molecular basis for the potential contribution of PB2 in the prevention of oxidative stress-related intestinal injury and gut pathologies.
原花青素 B2（PB2）是一种广泛存在于可可、红酒和葡萄汁中的天然类黄酮。最近的研究表明，PB2 通过调节内源性细胞防御，可防止结肠细胞发生氧化应激和化学诱导损伤。然而，这种保护的确切机制尚不完全清楚。在此，我们研究了 PB2 对与肠道保护相关的主要抗氧化/解毒酶之一——谷胱甘肽 S-转移酶 P1（GSTP1）的表达的影响，以及所涉及的分子机制。
用人结肠 Caco-2 细胞进行 PB2 处理，检测不同时间 GSTP1 的酶活性、mRNA 和蛋白水平。还研究了转录因子 NF-红细胞 2 相关因子（Nrf2）的核易位以及细胞内信号转导级联中关键蛋白的磷酸化状态。
PB2 诱导 GSTP1 的表达和活性以及 Nrf2 的核易位。有趣的是，Nrf2 易位涉及的两种重要信号蛋白，细胞外信号调节蛋白激酶（ERK）和 p38 丝裂原激活蛋白激酶（p38 MAPK）也被激活。这两条通路的特定抑制剂的进一步实验证实了它们在 PB2 诱导的有益作用中的关键作用。
本研究结果表明，PB2 通过激活 ERK 和 p38 MAPK 并促进 Nrf2 易位来保护结肠细胞免受氧化损伤，并上调 GSTP1 的表达。这些结果为 PB2 在预防与氧化应激相关的肠道损伤和肠道疾病中的潜在作用提供了分子基础。
