PPARγ乙酰化调控Klotho缓解慢性肾脏病矿物质与骨异常的作用及机理研究

Chronic kidney disease-mineral and bone disorder (CKD-MBD) is one of major threats to global public health. CKD-MBD patients at late stage show extensive cardiovascular cal-cification and osteosposis with very high mortality. Klotho is a recently discovered an-ti-aging gene highly expressed in the kidney tubule epithelial cells. CKD-MBD patients display decreased Klotho expression early in Kidney as well as reduced Klotho in blood and urine, suggesting that Klotho is an important biomarker of CKD-MBD. Peroxisome proliferator -activated receptor γ (PPARγ) is a nuclear membrane-bound hormone recep-tor/transcription factor that can be acetylated and directly regulates Klotho transcription. Based on our preliminary data, we hypothesized that PPARγ acetylation up-regulates Klotho and alleviates CKD-MBD pathogenesis. We propose in this project to evaluate the efficacy of PPARγ acetylation on the protection of CKD-MBD animal models, to examine the mode of PPARγ acetylation modification, and to study PPARγ acetylation regulation of Klotho transcription. The study will demonstrate the effectiveness of PPARγ acetylation and Klotho regulation on CKD-MBD therapy and elucidate its underlining mechanism.

慢性肾脏病矿物质与骨骼异常（CKD-MBD）是危害人类健康的重大慢性疾病。患者晚期出现血管软组织钙化，骨质病变等并发症，死亡率极高。Klotho是最近发现的抗衰老基因，在肾脏小管上皮细胞特异性高表达，而在CKD-MBD早期患者肾组织，血液，尿液中水平下降，是CKD-MBD的重要生物标记物。过氧化物酶体增殖物活化受体γ（PPARγ）能够被乙酰化修饰并增强对Klotho的转录上调功能。我们在前期工作的基础上提出PPARγ乙酰化上调Klotho缓解CKD-MBD损害的新假说，从PPARγ乙酰化调控保护CKD-MBD模型小鼠病理改变， PPAR-γ乙酰化修饰机理，及对靶基因Klotho的上调作用三个方面探讨PPARγ乙酰化干预缓解CKD-MBD的有效性和作用机理，为设计以Klotho为靶点的CKD-MBD新治疗措施提供分子生物学依据。

本课题探讨干预蛋白质乙酰化异常抗慢性肾脏病伴骨质和矿物质异常的有效作用和作用机制，我们以腺嘌呤喂养小鼠诱导慢性肾脏病和矿物质及骨密度异常为模型，采用组蛋白去乙酰化酶抑制剂为实验手段，发现1. 广谱HDAC抑制剂TSA能够有效缓解小鼠模型的肾脏和骨质病理改变并缓解Klotho下调；2. TSA能够增加PPARg赖氨酸240和265位点的乙酰化修饰并增加其转录调控下游Klotho基因转录，3. 我们用PPARg基因敲除小鼠为工具，证实HDAC抑制剂TSA依赖对PPARg的激活作用而发挥抗慢性肾脏病作用；4. 我们进一步发现HDAC3亚型在慢性肾脏病小鼠肾脏 选择性高表达，特异性抑制HDAC3能够缓解TGFb诱导的Klotho下调和肾脏损伤相关蛋白紊乱，5. 特异性HDAC3抑制剂RGFP966也能Klotho依赖性的缓解小鼠慢性肾脏病的病理变化。因此我们的课题揭示了表观遗传蛋白质乙酰化影响慢性肾脏病形成的新机制及干预异常HDAC治疗慢性肾脏病及相关矿物质和骨异常的新靶点。