Gobé G C, Buttyan R, Wyburn K R, Etheridge M R, Smith P J
Department of Pathology, University of Queensland Medical School, Brisbane, Australia.
Kidney Int. 1995 Feb;47(2):411-20. doi: 10.1038/ki.1995.54.
To analyze the role of clusterin in renal diseases involving a regenerative process, we have used a novel rodent model to compare temporal and spatial expression of clusterin mRNA. Thus, renal artery stenosis was used to induce unilateral non-infarctive renal atrophy. After several weeks, when cellular pathology of atrophic kidneys involved minimal apoptosis or inflammatory response and mitosis was at normal levels, regeneration of atrophic kidneys was stimulated by removal of the contralateral healthy kidneys. The regrowth response was very rapid and involved renal hyperplasia rather than hypertrophy. Regenerating kidneys were studied 0, 4, 8, 24 hours and 2, 3, 5, 7, and 14 days after contralateral nephrectomy. Several parameters were compared: level and localization of clusterin mRNA; cell proliferation; cell dedifferentiation and redifferentiation and apoptosis. During the acute regenerative phase (first 24 hr) clusterin expression was markedly increased, decreasing to untraceable levels by five days of regeneration. Clusterin mRNA was localized in dilated or collapsed atrophic tubules that had lost identifying surface structures of normal tubular epithelium (termed dedifferentiated). Clusterin was also localized in the periphery of some blood vessel walls. Cell proliferation peaked at three to five days of regeneration, and was also localized in dedifferentiated tubules. Despite the regenerative stimulus, an unexpected result was a transient but marked increase in apoptotic cell death in atrophic tubules in the first 24 hours of regeneration. Our results provide evidence of a temporal association between increased clusterin expression and apoptosis, but in situ localization showed clusterin mRNA over apparently viable, as well as apoptotic, cells in the epithelium of tubules showing clusterin expression. Clusterin mRNA was rarely identified over epithelial cells in foci of non-atrophic (non-dedifferentiated) nephrons that responded to the regenerative stimulus by cellular hypertrophy. The dramatic response after initiation of regeneration, especially the initiation of apoptosis in the tubular epithelium, may have applications for the study of genetic changes leading to renal oncogenesis.
为了分析簇集素在涉及再生过程的肾脏疾病中的作用，我们使用了一种新型啮齿动物模型来比较簇集素mRNA的时空表达。因此，采用肾动脉狭窄诱导单侧非梗死性肾萎缩。几周后，当萎缩肾脏的细胞病理学涉及最小程度的凋亡或炎症反应且有丝分裂处于正常水平时，通过切除对侧健康肾脏来刺激萎缩肾脏的再生。再生反应非常迅速，涉及肾脏增生而非肥大。在对侧肾切除术后0、4、8、24小时以及2、3、5、7和14天对再生肾脏进行研究。比较了几个参数：簇集素mRNA的水平和定位；细胞增殖；细胞去分化和再分化以及凋亡。在急性再生期（最初24小时），簇集素表达明显增加，到再生5天时降至无法检测的水平。簇集素mRNA定位于已失去正常肾小管上皮识别表面结构（称为去分化）的扩张或塌陷的萎缩肾小管中。簇集素也定位于一些血管壁的周边。细胞增殖在再生3至5天时达到峰值，也定位于去分化的肾小管中。尽管有再生刺激，但一个意外的结果是在再生的最初24小时内萎缩肾小管中的凋亡细胞死亡出现短暂但显著的增加。我们的结果提供了簇集素表达增加与凋亡之间存在时间关联的证据，但原位定位显示簇集素mRNA存在于显示簇集素表达的肾小管上皮中明显存活以及凋亡的细胞上。在非萎缩（非去分化）肾单位灶中，通过细胞肥大对再生刺激作出反应的上皮细胞上很少能识别出簇集素mRNA。再生开始后的剧烈反应，尤其是肾小管上皮细胞凋亡的启动，可能对导致肾肿瘤发生的基因变化的研究有应用价值。
