β-catenin/FoxO6信号通路通过靶向抑制线粒体功能促进肾脏衰老的作用及机制研究

The decline of organ function caused by aging has become a public health problem in China. Kidney is an important organ, especially renal tubular epithelial cells, which play important roles in metabolism and endocrine function. The cell aging in renal tubular cells causes loss of renal function and development of renal fibrosis, and induces metabolic disorders, which seriously threatens health. However, the mechanism of tubular cell aging has not been elucidated. Previous results of the applicant showed that activation of β-catenin signaling promoted renal tubular cell aging and renal fibrosis. The mechanism is closely related to the damage of mitochondrial biogenesis. However, the mechanism of mitochondrial dysfunction induced by β-catenin in renal tubular cells has not been reported. Our preliminary data suggest that FoxO6 may play an important role in β-catenin-induced renal tubular cell aging. To clarify the mechanism, we would adopt cultured renal tubular epithelial cells, natural aging and accelerated aging mice and FoxO6 gene knockout mice models to study the role of β-catenin signaling in renal tubular cell aging and mitochondrial dysfunction. Especially, we would clarify the mediating role of β-catenin /FoxO6 signaling in renal aging through downregulation of PGC-1α, the key regulator of mitochondrial biogenesis. Furthermore, we would study the anti-aging effects of small molecule compound which targets β-catenin. Our study would further clarify the pathogenesis of renal aging and develop new intervention strategies.

我国人口老龄化引起的器官功能减退已成公共健康问题。肾脏是人体重要器官，尤其肾小管上皮细胞承担代谢和内分泌等重要功能。肾小管细胞衰老引起肾功能丢失及肾纤维化，导致代谢紊乱，严重威胁健康。然而其发病机制尚未阐明。申请者的前期结果表明，β-catenin信号活化后促进肾小管细胞衰老和肾纤维化，其机制与线粒体生物发生功能损伤密切相关。但是β-catenin诱导肾小管细胞线粒体功能损伤的途径未见报道。预实验结果提示，FoxO6具有重要参与作用。为明确机制，本项目拟采用肾小管上皮细胞、自然及加速衰老小鼠、FoxO6基因敲除小鼠等模型，深入研究β-catenin信号参与肾小管细胞衰老和线粒体损伤的作用和机制；阐明β-catenin/FoxO6信号调控线粒体生物发生关键调控因子PGC-1α的损伤途径；研究靶向抑制β-catenin的小分子药物对于肾脏衰老的作用，从而明确肾脏衰老的致病机制并发展新干预途径。

肾脏衰老引起肾功能减退及代谢失调，严重危害人体健康。但是肾脏衰老和衰老相关肾纤维化的机制未明。我们进行相关的研究：1.发现β-catenin/FoxO6调控线粒体功能和能量代谢介导肾脏衰老和衰老性肾纤维化。我们发现，Wnt/β-catenin在肾脏衰老时表达增加，并与线粒体功能损伤密切相关。线粒体功能受到PGC-1α信号通路调节，我们发现Wnt/β-catenin信号显著抑制PGC-1α，损伤线粒体生物发生，导致能量代谢障碍，加速肾上皮细胞衰老，诱导衰老相关肾纤维化。深入探究内在机制，我们发现Wnt/β-catenin信号激活FoxO6转录因子，从而抑制PGC-1α转录，诱导线粒体功能障碍。采用β-catenin降解剂KYA1797K能有效缓解肾衰老和衰老相关肾纤维化。我们分别采用了β-catenin肾小管特异敲除及FoxO6敲除小鼠，D-gal诱导的加速衰老和自然衰老模型，深入探究了β-catenin/FoxO6信号调控线粒体功能和抑制脂肪酸氧化代谢的机制，明确了β-catenin/FoxO6信号在肾脏衰老中的重要作用，为寻找肾脏衰老新的干预靶标提供新的理论和重要策略。2.发现了β-catenin/OPN信号诱导外泌体微环境是肾脏细胞衰老和纤维化的新机制。我们发现β-catenin活化后促进肾小管上皮细胞分泌外泌体，并分泌骨桥蛋白（OPN）进入外泌体中，尤其是其N-末端片段（N-OPN），随后传递给成纤维细胞，与成纤维细胞CD44受体结合，促进成纤维细胞增殖和活化，从而诱导肾纤维化。表明Wnt/β-catenin/OPN/CD44 信号轴是肾纤维化的关键机制。3.发现有效治疗肾脏纤维化的新药物。肝激酶B1（LKB1）是能量代谢和细胞稳态的关键调节因子。我们从海洋来源的链霉菌菌株提取纯化得到一种粉蝶霉素 A 糖苷类似物 (PA-S14)，发现其与LKB1激酶结构域中的D176残基结合，通过磷酸化并且与MO25和STRADα形成复合物诱导LKB1激活，有效抑制肾脏细胞衰老，缓解肾纤维化。上述结果为肾细胞衰老及衰老相关肾纤维化提供了重要创新理论，为肾脏衰老防治提供了重要干预策略。在项目资助下，发表SCI论文18篇(5篇一区且IF>10)，总IF139。项目负责人周丽丽后续获得国家杰青资助。培养博士后4人，博硕士研究生7人。