Division of Nephrology, Huashan Hospital, Shanghai Medical College, Fudan Univ., Shanghai, China.
Am J Physiol Renal Physiol. 2012 Dec 1;303(11):F1534-44. doi: 10.1152/ajprenal.00083.2012. Epub 2012 Sep 19.
The characteristics of renal tubular progenitor/precursor cells and the role of renal tubule regeneration in the repair of remnant kidneys (RKs) after nephrectomy are not well known. In the present study of a murine model of subtotal nephrectomy, we used immunofluorescence (IF), immunoblot analysis, and in situ hybridization methods to demonstrate that nestin expression was transiently upregulated in tubule cells near the incision edges of RKs. The nestin-positive tubules were immature proximal tubules that colabeled with lotus tetragonolobus agglutinin but not with markers of mature tubules (aquaporin-1, Tamm-Horsfall protein, and aquaporin-2). In addition, many of the nestin-expressing tubule cells were actively proliferative cells, as indicated by colabeling with bromodeoxyuridine. Double-label IF and immunoblot analysis also showed that the upregulation of tubular nestin was associated with enhanced transforming growth factor-β1 (TGF-β1) expression in the incision edge of RKs but not α-smooth muscle actin, which is a marker of fibrosis. In cultured human kidney proximal tubule cells (HKC), immunoblot analysis indicated that TGF-β1 induced nestin expression and loss of E-cadherin expression, suggesting an association of nestin expression and cellular dedifferentiation. Knockdown of nestin expression by a short hairpin RNA-containing plasmid led to decreased migration of HKC cells that were induced by TGF-β1. Taken together, our results suggest that the tubule repair that occurs during the recovery process following nephrectomy may involve TGF-β1-induced nestin expression in immature renal proximal tubule cells and the promotion of renal cell migration.
肾小管祖/前体细胞的特征以及肾小管再生在肾切除术后残肾 (RK) 修复中的作用尚不清楚。在本研究中，我们使用免疫荧光 (IF)、免疫印迹分析和原位杂交方法，在肾部分切除的小鼠模型中证明了 nestin 在 RK 切口边缘附近的肾小管细胞中短暂上调。nestin 阳性的肾小管是不成熟的近端肾小管，与 Lotus tetragonolobus agglutinin 共标记，但不与成熟肾小管的标志物 (水通道蛋白-1、Tamm-Horsfall 蛋白和水通道蛋白-2) 共标记。此外，许多表达 nestin 的肾小管细胞是活跃的增殖细胞，如溴脱氧尿苷共标记所示。双标记 IF 和免疫印迹分析还表明，管状 nestin 的上调与 RK 切口边缘 TGF-β1 表达的增强有关，但与纤维化标志物 α-平滑肌肌动蛋白无关。在培养的人肾近端肾小管细胞 (HKC) 中，免疫印迹分析表明 TGF-β1 诱导 nestin 表达和 E-钙黏蛋白表达的丧失，表明 nestin 表达与细胞去分化有关。短发夹 RNA 质粒介导的 nestin 表达敲低导致 TGF-β1 诱导的 HKC 细胞迁移减少。综上所述，我们的结果表明，肾切除术后恢复过程中发生的肾小管修复可能涉及 TGF-β1 诱导不成熟肾近端小管细胞中 nestin 的表达，并促进肾细胞迁移。
