Novel insights into changes in biochemical properties of keratins 8 and 18 in griseofulvin-induced toxic liver injury
Novel insights into changes in biochemical properties of keratins 8 and 18 in griseofulvin-induced toxic liver injury
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DOI：
10.1016/j.yexmp.2010.07.004
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发表时间：
2010-10-01
影响因子：
3.6
通讯作者：
Cadrin, Monique
中科院分区：
文献类型：
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作者：
Fortier, Anne-Marie;Riopel, Kathleen;Cadrin, Monique
角蛋白8和18(K8/18)中间丝蛋白被认为在保护肝细胞免受机械应激和毒性应激中起重要作用。这一断言主要是基于在K8/18基因缺陷或K8/18基因突变的转基因小鼠中观察到的肝细胞脆性增加。角蛋白实现其保护功能的分子机制尚未完全阐明。肝病，如酒精性肝炎和铜代谢疾病，与肝细胞中中间丝组织的改变和含有K8/18的聚集体Mallory-Denk小体的形成有关。用含有灰黄腐素的饲料处理小鼠，可诱导肝细胞中Mallory-Denk小体的形成。这为评估角蛋白在肝细胞对化学损伤的反应中发挥保护作用的分子机制提供了可靠的动物模型。在这项研究中，我们发现灰黄霉素中毒引起了角蛋白溶解度的变化，可溶性角蛋白的相对量增加了5%到25%。角蛋白在特定位点(K8pS79、K8pS436和K18pS33)上的磷酸化增加，并在不溶蛋白组分中显著增加。由于在GF处理后至少检测到6个K8磷酸化表位，因此需要考虑所研究的以外的磷酸化位点。免疫荧光染色显示K8079表位存在于围绕凋亡细胞的肝细胞簇中。激活的p38MAPK与K8 pS79阳性细胞相关，但不存在于K8 pS79阳性细胞中。这些结果表明，灰黄腐素中毒介导角蛋白的物理化学性质的改变，导致角蛋白中间丝的重塑，而角蛋白中间丝又可以通过改变它们与信号蛋白的结合来调节它们所涉及的信号通路。(C)2010 Elsevier Inc.保留所有权利。
Keratins 8 and 18 (K8/18) intermediate filament proteins are believed to play an essential role in the protection of hepatocytes against mechanical and toxic stress. This assertion is mainly based on increased hepatocyte fragility observed in transgenic mice deficient in K8/18, or carrying mutations on K8/18. The molecular mechanism by which keratins accomplish their protective functions has not been totally elucidated. Liver diseases such as alcoholic hepatitis and copper metabolism diseases are associated with modifications, in hepatocytes, of intermediate filament organisation and the formation of K8/18 containing aggregates named Mallory-Denk bodies. Treatment of mice with a diet containing griseofulvin induces the formation of Mallory-Denk bodies in hepatocytes. This provides a reliable animal model for assessing the molecular mechanism by which keratins accomplish their protective role in the response of hepatocytes to chemical injuries. In this study, we found that griseofulvin intoxication induced changes in keratin solubility and that there was a 5% to 25% increase in the relative amounts of soluble keratin. Keratin phosphorylation on specific sites (K8 pS79, K8 pS436 and K18 pS33) was increased and prominent in the insoluble protein fractions. Since at least six K8 phosphoepitopes were detected after GF treatment, phosphorylation sites other than the ones studied need to be accounted for. Immunofluorescence staining showed that K8 079 epitope was present in clusters of hepatocytes that surrounded apoptotic cells. Activated p38 MAPK was associated with, but not present in K8 pS79-positive cells. These results indicate that griseofulvin intoxication mediates changes in the physicochemical properties of keratin, which result in the remodelling of keratin intermediate filaments which in turn could modulate the signalling pathways in which they are involved by modifying their binding to signalling proteins. (C) 2010 Elsevier Inc. All rights reserved.