Cadrin M, Anderson N M, Aasheim L H, Kawahara H, Franks D J, French S W
Département de Chimie-Biologie, Université du Québec a Trois-Rivières, Canada.
Lab Invest. 1995 Apr;72(4):453-60.
Hepatocytes from mice fed griseofulvin (GF) for 8 months form Mallory bodies (MBs), which represent a pathologic state of intermediate filaments (IFs). The cellular mechanisms that lead to MB formation are not known.
This study was aimed to investigate if MB formation could be related to modification in cytokeratin (CK) metabolism. Primary cultures of hepatocytes from control and GF livers were studied. Immunofluorescence microscopy was used to study the organization of the cytoskeleton in these cells. The hepatocytes were labeled with [35S]methionine or [32P]orthophosphate to study, respectively, the level of amino acid incorporation into IF proteins (CK 8 and CK 18) and their phosphorylation levels. The response to the tumor promoter 12-O-tetradecanoyl-phorbol-13-acetate stimulation of the phosphorylation of CK 8 and CK 18 was also elicited in contrast to control hepatocytes.
We found that there was a change in the organization of actin and the IF network in the hepatocytes from GF-treated animals. This was associated with an increase in labeled amino acid incorporation into CK 8 and CK 18 as well as in actin. Although there was no significant difference in the absolute level of CK phosphorylation, we found modifications in the phosphorylated isomers of CK 8, the more phosphorylated isomers becoming more prominent. The treatment of the hepatocytes with 12-O-tetradecanoyl-phorbol-13-acetate did not induce changes in the level of CK phosphorylation in GF-pretreated hepatocytes.
These results suggest that the modification of the IF network and MB formation are the consequences of increased CK synthesis and the modification of phosphorylation. They could alter the normal interaction of the IFs with different cellular components, which results in conformational changes of CKs and the reorganization of the IF network to the form of MBs.
用灰黄霉素（GF）喂养8个月的小鼠肝细胞会形成马洛里小体（MBs），其代表中间丝（IFs）的一种病理状态。导致MB形成的细胞机制尚不清楚。
本研究旨在调查MB的形成是否可能与细胞角蛋白（CK）代谢的改变有关。对来自对照和GF处理肝脏的肝细胞进行原代培养并加以研究。利用免疫荧光显微镜来研究这些细胞中细胞骨架的组织情况。用[35S]甲硫氨酸或[32P]正磷酸盐标记肝细胞，分别以研究氨基酸掺入IF蛋白（CK 8和CK 18）的水平及其磷酸化水平。与对照肝细胞相比，还引发了对肿瘤促进剂12 - O - 十四烷酰佛波醇 - 13 - 乙酸酯刺激的CK 8和CK 18磷酸化反应。
我们发现，经GF处理的动物的肝细胞中，肌动蛋白和IF网络的组织发生了变化。这与标记氨基酸掺入CK 8、CK 18以及肌动蛋白的增加有关。尽管CK磷酸化的绝对水平没有显著差异，但我们发现CK 8的磷酸化异构体有变化，磷酸化程度更高的异构体变得更加突出。用12 - O - 十四烷酰佛波醇 - 13 - 乙酸酯处理肝细胞，在GF预处理的肝细胞中并未诱导CK磷酸化水平的变化。
这些结果表明，IF网络的改变和MB的形成是CK合成增加和磷酸化改变的结果。它们可能会改变IF与不同细胞成分的正常相互作用，从而导致CK的构象变化以及IF网络重组为MB的形式。
