LIF-STAT3 on renal tubular regeneration process examined by Cre/loxP system

本研究的目的是阐明LIF-gp 130-STAT3信号系统中涉及的基因如何作用于Cre/loxP转基因小鼠的肾小管再生。我们成功地在表达Cre的细胞中产生了表达LIF的LoxP-LIF小鼠。将LoxP-LIF小鼠与α - mhc - cre小鼠杂交，产生LIF在心肌细胞中高表达的小鼠。小鼠交感神经元和副交感神经元的分布模式转变为心力衰竭模式。另一方面，我们试图在近端小管S3段的肾小管细胞中产生Cre特异性表达的小鼠。而AQP7-Cre和GGT2-Cre小鼠没有S3段特异性表达Cre。我们与东京都医学研究所实验动物科学部的Michiko Sekine合作，对Gsl5-EGFP小鼠和Gsl5-HB-EGF小鼠进行了分析。Gsl5被证明定位于核心2 [β]- 1,6 - n -乙酰氨基葡萄糖转移酶的启动子区域，并被证明是负责近端S3小管细胞特异性转录的顺式调控元件。利用Gsl5，我们培育了人肝素抑制egf样生长因子（HB-EGF）在近端小管S3段的小管细胞中特异性表达的转基因小鼠。小鼠对白喉毒素（DT）具有抗性是因为小鼠HB-EGF不结合DT。相比之下，人HB-EGF以高亲和力结合DT。在Gsl5-HB-EGF中，DT对近端小管S3段的小管细胞有特异性消融作用。通过小鼠实验，我们阐明了急性肾衰和肾小管细胞再生的机制。肾小管上皮-间质转化（EMT）在肾脏疾病中的病理意义越来越被人们所认识。我们证明了转录因子Snail参与肾小管EMT， TGF-beta1在转录和蛋白质降解水平上调节Snail。

The purpose of this study is to clarify how the genes involved in LIF-gp 130-STAT3 signal systems act on renal tubular regeneration by Cre/loxP transgenic mice. We succeeded in generating LoxP-LIF mice which expressed LIF in cells expressing Cre. Crossing LoxP-LIF mice with alfa-MHC-Cre mice generated mice in which LIF is highly expressed in myocardiocytes. In the mice, distribution pattern of sympathetic neurons and parasympathetic neurons turned into heart failure pattern. On the other hand, we tried to generated mice in which Cre expresses specifically in renal tubular cells in S3 segment of proximal tubules. However, AQP7-Cre and GGT2-Cre mice did not show S3 segments specific expression of Cre.We analyzed Gsl5-EGFP mice and Gsl5-HB-EGF mice collaborating with Michiko Sekine at Department of Laboratory Animal Science, Tokyo Metropolitan Institute of Medical Science. Gsl5 was shown to be localized in the promoter region of core 2 [beta]-1, 6-N-Acetylglucosaminyl transferase, and was shown to be a cis-regulatory element responsible for proximal S3 tubular cell-specific transcription. Utilizing the Gsl5, we generated transgenic mice in which the human heparin-biding EGF-like growth factor (HB-EGF) is specifically expressed in tubular cells in proximal tubule S3 segment. Mice are resistant to diphtheria toxin (DT) because mice HB-EGF does not bind DT. In contrast, human HB-EGF binds DT at high affinity. In Gsl5-HB-EGF, tubular cells in proximal tubule S3 segment were ablated specifically after administration of DT. Using the mice, we clarified the mechanism of acute renal failure and regeneration of tubular cells.The pathological significance of the tubular epithelial-mesenchymal transition (EMT) in kidney diseases is becoming increasingly recognized. We demonstrated that transcriptional factor Snail is involved in renal tubular EMT and that TGF-beta1 regulates Snail at the transcription and protein degradation levels.