Akt/ACLY/PI3K-Akt反馈环路对破骨细胞分化的调控作用及相关表观遗传学机制研究

破骨细胞的过度活化是骨质疏松发生的重要病理基础。ATP依赖的柠檬酸裂解酶（ACLY）是细胞内连接糖脂代谢的关键酶，其产物乙酰辅酶A可通过组蛋白乙酰化参与表观调控。申请人前期实验发现在破骨细胞分化过程中ACLY逐渐激活并入核增加，抑制ACLY能抑制破骨细胞分化并能缓解卵巢切除小鼠的骨量丢失。进一步实验发现在ACLY调节破骨细胞分化的过程中存在Akt/ACLY/PI3K-Akt反馈环路，而且ACLY会影响组蛋白的乙酰化和代谢相关基因的转录，但该环路的表观调控机制及对代谢的影响尚不明确。申请人团队推测Akt/ACLY/PI3K-Akt环路通过调控组蛋白乙酰化参与破骨细胞分化。本项目拟利用ACLY条件性敲除小鼠模型,结合离体细胞实验，阐明Akt/ACLY/PI3K-Akt环路内部的调控机制、其在破骨细胞分化过程中的表观调控机制及其对代谢改变的影响，明确其参与破骨细胞分化的具体机制。

Overactivation of osteoclasts is the key pathological basis of osteoporosis. ATP-citrate lyase (ACLY) is an important enzyme linking carbohydrate to lipid metabolism, acetyl-CoA generated by which can contribute to histone acetylation related with epigenetic regulation. In our preliminary experiments, we found that ACLY was activated and shifted from cytosol to nuclear during osteoclastogenesis, inhibition of ACLY resulted in osteoclastogenesis suppression and could alleviate ovariectomy-induced bone loss. Further we found that there existed an Akt/ACLY/PI3K-Akt feedback loop enrolled in the regulation process of ACLY during osteoclastogenesis and ACLY could alter histone acetylation level and transcription of metabolism-related genes, but the exact epigenetic regulation mechanism of this loop and its impact on metabolism remained unclear. We thus speculate that the Akt/ACLY/PI3K-Akt loop plays a role in osteoclastogenesis through regulating histone acetylation. In this project we will perform experiments in conditional gene knockout mouse models combined with in vitro cell experiments. In this way we want to study the regulation mechanism inside the Akt/ACLY/PI3K-Akt loop, its epigenetic regulation mechanism and its effect on metabolic changes during osteoclastogenesis, so that to elucidate the exact regulation mechanism of Akt/ACLY/PI3K-Akt feedback loop during osteoclastogenesis.