Banan A, Smith G S, Rieckenberg C L, Kokoska E R, Miller T A
Theodore Cooper Surgical Research Institute, Department of Surgery, Saint Louis University Medical Center, Missouri 63104, USA.
Am J Physiol. 1998 Jan;274(1):G111-21. doi: 10.1152/ajpgi.1998.274.1.G111.
Prostaglandins have been shown to protect the gastrointestinal (GI) epithelium from injury induced by various luminal insults independent of their known acid-inhibitory effects, a process termed "cytoprotection." The mechanism of this protective action remains unknown. The present investigation determined the role of microtubules (a major cytoskeletal component) in GI injury induced by ethanol (EtOH) and its prevention by 16,16-dimethylprostaglandin E2 (dmPGE2) using cells from a human colonic cell line known as Caco-2 cells. These cells were preincubated in Eagle's minimum essential medium with and without dmPGE2 (2.6 microM) for 15 min and subsequently incubated in media containing 1, 2.5, 5, 7.5, and 10% EtOH. The effects on cell viability and tubulin (the major protein backbone of microtubules) were then determined. EtOH concentrations > or = 2.5% extensively disrupted the microtubules as demonstrated by fragmentation, kinking, and perturbation of the microtubule organizer center. EtOH treatment also led to a significant decrease in the S2 (polymerized) fraction and an increase in the S1 (monomeric) pool of tubulin. Concomitant with these effects were marked decreases in cellular viability. DmPGE2 pretreatment abolished the disruption of microtubules, significantly increased the S2 fraction of tubulin, and increased cellular viability in cultures exposed to EtOH. Furthermore, pretreatment with colchicine, an inhibitor of microtubule assembly, prevented the cytoprotective action of dmPGE2. Taxol, a microtubule stabilizing agent, mimicked the effects of dmPGE2 by also enhancing microtubule integrity and increasing cellular viability in cells exposed to EtOH. Our data indicate that organization and stabilization of microtubules may play an essential role in the mechanism of prostaglandin-induced protection.
前列腺素已被证明可保护胃肠道（GI）上皮免受各种管腔损伤诱导的伤害，这一过程独立于其已知的酸抑制作用，被称为“细胞保护”。这种保护作用的机制尚不清楚。本研究使用人结肠癌细胞系Caco-2细胞，确定了微管（一种主要的细胞骨架成分）在乙醇（EtOH）诱导的胃肠道损伤及其被16,16-二甲基前列腺素E2（dmPGE2）预防中的作用。这些细胞在含有和不含有dmPGE2（2.6 microM）的伊格尔最低限度基本培养基中预孵育15分钟，随后在含有1%、2.5%、5%、7.5%和10% EtOH的培养基中孵育。然后确定对细胞活力和微管蛋白（微管的主要蛋白质骨架）的影响。EtOH浓度≥2.5%会广泛破坏微管，表现为微管断裂、扭结和微管组织中心紊乱。EtOH处理还导致微管蛋白的S2（聚合）部分显著减少，S1（单体）池增加。与这些影响同时出现的是细胞活力显著下降。dmPGE2预处理消除了微管的破坏，显著增加了微管蛋白的S2部分，并提高了暴露于EtOH的培养物中的细胞活力。此外，用微管组装抑制剂秋水仙碱预处理可防止dmPGE2的细胞保护作用。紫杉醇是一种微管稳定剂，可以模拟dmPGE2的作用，增强微管完整性，并提高暴露于EtOH的细胞的活力。我们的数据表明，微管的组织和稳定可能在前列腺素诱导的保护机制中起重要作用。
