雌激素受体β在肾脏纤维化发生中的作用及其作用机制

Chronic kidney disease (CKD) is a great threaten to human health, Renal fibrosis is the common pathophysiology of CKD patients. So it is of great significance to clarify the pathogenesis of renal fibrosis for the treatment of CKD. Increasing evidence suggests that estrogen can protect the kidney by inhibition renal fibrosis, but the underlying mechanisms is still unknown. In the preliminary study, we found that estrogen receptor β (ERβ) is highly expressed in the kidney, and ERβ was significantly down-regulated both in human and mouse fibrotic kidney tissues, what’s more, ERβ-specific agonist DPN can significantly reduce the expression of collgen I and Snail1 in the treatment of TGFβ1in primary tubular epithelial cells(PTECs). Snail1 (zinc finger protein 1) can aggravate renal fibrosis through increasing renal tubular epithelial to mesenchymal transition (EMT) . It’s reported that estrogen receptor (ER) can inhibit tumor cell’s EMT by downregulation of Snail1. Based on these data, the hypothesis of the current project is that estrogen can protect the kidney from fibrosis through ERβ , and ERβ can improve renal fibrosis by inhibiting Snail1and PTECs EMT. The project intends to: 1）Investigate the role of ERβ by using ERβ Specific agonist and ERβ knockout mice in vivo; 2) Explore the function of ERβ in renal tubular epithelia EMT; 3）Investigate the role of Snail1in renal tubular epithelia EMT；4）Detect the expression of Snail1in CKD patients. This study may extend our knowledge of the molecular mechanism of estrogen attenuated renal fibrosis and potentially contribute to the development of novel therapeutic approaches to it.

慢性肾脏病（CKD）严重危害人类健康，肾脏纤维化是慢性肾脏病的共同病理改变，但其机制不详，尚缺少有效治疗方法。雌激素通过改善肾纤维化保护肾脏，且预实验结果发现，在人和小鼠纤维化肾组织中，雌激素受体β（ERβ）表达明显下调，激活ERβ可抑制肾小管细胞胶原分泌，提示ERβ在肾纤维化中具有保护作用。锌指蛋白1（Snail1）可诱导小管细胞EMT而加重肾纤维化。申请人发现，在原代小管上皮细胞中激活ERβ显著降低了snail 1的表达。因此提出科学假说：激活ERβ可通过抑制Snail1而减少小管细胞EMT，最终改善肾脏纤维化。本项目拟：1）体内使用ERβ激动剂及ERβ敲除小鼠研究ERβ在肾纤维化中的作用；2）培养原代小管上皮细胞，研究ERβ在细胞EMT中的作用；3）探究Snail1在ERβ改善小管细胞EMT中的作用；4）明确CKD病人肾Snail1表达变化。以期为肾脏纤维化治疗提供新的潜在靶点。

慢性肾脏病（CKD）严重危害人类健康，肾脏纤维化（Renal Fibrosis）是慢性肾脏病的共同病理改变，但其机制不详，尚缺少有效治疗方法。已有文献报道雌激素具有抗肾脏纤维化作用，能够延缓慢性肾脏疾病的进展，但是雌激素究竟是通过哪种受体发挥抗肾脏纤维化作用的目前仍然不清楚。本项目运用动物实验、细胞实验和分子生物学实验研究了雌激素受体β（ERβ）在肾脏纤维化中的作用及其作用机制。首先本项目明确了ERβ在野生型C57小鼠肾脏中的定位，其主要表达在近端小管上皮细胞。左侧输尿管梗阻肾脏纤维化模型（UUO）中ERβ表达明显下调，ERβ基因敲除可以加重肾脏纤维化损伤，ERβ特异性激动剂能够明显改善肾脏纤维化损伤，敲除Smad3基因或者使用Smad3特异性抑制剂能够阻断ERβ的抗纤维化作用。为了探究其作用机制，我们培养了原代近端肾小管上皮细胞（PTECs），发现PTECs细胞中存在ERβmRNA和蛋白的表达，与此同时，我们还使用了小鼠肾小管上皮细胞系MTCs,我们也检测到了ERβmRNA和蛋白的表达。TGFβ1可以计量依赖性降低ERβmRNA和蛋白的表达，然而ERβ激动剂WAY200070处理能够明显减少TGFβ1诱导的MTCs细胞a-SMA和胶原I表达的增加，并且这种作用及计量依赖性的。进一步研究发现Smad3能够特异性与ERβ启动子上游SBE结合，抑制ERβ转录，从而加重肾脏纤维化进展。本项目明确了ERβ是Smad3的直接靶基因，ERβ激活能够改善肾脏纤维化，开发ERβ特异性激动剂有望用来治疗肾脏纤维化。在本项目的资助下，于Am J Physiol Renal Physiol, Kidney Dis (Basel)发表文章2篇，此外文章“ERβ attenuates renal fibrosis through the TGFβ/Smad3 pathway” 目前正投稿于PNAS（IF:9.89）。..