Schiaffonati L, Rappocciolo E, Tacchini L, Cairo G, Bernelli-Zazzera A
Istituto di Patologia Generale dell'Università degli Studi di Milano, Centro Studio sulla Patologia Cellulare, Italy.
J Cell Physiol. 1990 Apr;143(1):79-87. doi: 10.1002/jcp.1041430110.
Steady-state levels of messenger RNA (mRNA) for different members of the heat-shock protein 70 gene family were studied in rat livers reperfused after non-necrogenic ischemia. The expression of constitutive hsc 73 gene decreases during ischemia, returns to normal upon reperfusion, and increases 4 hr after restoration of blood flow. Reperfusion induces the expression of another hsp 70 gene family member (the so-called inducible hsp 70 gene), which remains at high levels for at least 7 hr. The induction of hsp 70 family genes is preceded by activation of the cellular oncogene c-fos, the most prompt change in gene expression detected in reperfused liver. Run-on experiments demonstrate that the increased expression of these genes is largely dependent on activation of transcription. Changes in the amount of c-myc and ornithine decarboxylase mRNA are not evident, while the level of the mRNA for glucose-regulated protein GRP 78 increases later, concurrent with the onset of the acute phase response to surgical trauma. Analysis of polysomal and nonpolysomal fractions from sucrose gradients indicates that in postischemic liver, hsp 70 and hsc 73 mRNA are rapidly engaged on light polysomal or nonpolysomal complexes and are later shifted to polysomes. Albumin mRNA displays the same behavior, indicating that hsp 70 mRNA are not preferentially translated and that increased transcription is the major mechanism for enhanced hsp synthesis in postischemic liver. Damage by active oxygen species, pressure overload, and derangements of protein synthesis is likely to include the causative factors of increased expression of c-fos and the hsp 70 gene family in postischemic reperfused liver.
在非致死性缺血后再灌注的大鼠肝脏中，研究了热休克蛋白70基因家族不同成员的信使核糖核酸（mRNA）稳态水平。组成型hsc 73基因的表达在缺血期间降低，再灌注时恢复正常，并在血流恢复后4小时增加。再灌注诱导热休克蛋白70基因家族另一个成员（即所谓的诱导型hsp 70基因）的表达，该成员至少7小时维持在高水平。hsp 70家族基因的诱导之前是细胞癌基因c-fos的激活，这是在再灌注肝脏中检测到的最迅速的基因表达变化。连续转录实验表明，这些基因表达的增加很大程度上依赖于转录激活。c-myc和鸟氨酸脱羧酶mRNA量的变化不明显，而葡萄糖调节蛋白GRP 78的mRNA水平稍后增加，与对手术创伤的急性期反应开始同时出现。对蔗糖梯度的多核糖体和非多核糖体组分的分析表明，在缺血后肝脏中，hsp 70和hsc 73 mRNA迅速与轻度多核糖体或非多核糖体复合物结合，随后转移到多核糖体上。白蛋白mRNA表现出相同的行为，表明hsp 70 mRNA没有被优先翻译，转录增加是缺血后肝脏中hsp合成增强的主要机制。活性氧损伤、压力过载和蛋白质合成紊乱可能是缺血后再灌注肝脏中c-fos和hsp 70基因家族表达增加的致病因素。
