MACF1通过FOXO1/β-catenin通路调节成骨细胞抗氧化参与模拟失重抑制骨形成的机制研究

The increased oxidative stress and decreased differentiation ability of osteoblast induced by weight loss is the main cause of weightlessness-induced bone loss. However, the mechanism is still unclear. FOXO1 antioxidant pathways is particularly important in signaling networks that regulate osteoblast differentiation, which requires β-catenin to initiate downstream gene transcription. Our team found that simulated weight loss conditions decreased MACF1 expression in osteoblasts, reduced the antioxidant, differentiation and mineralization capacity of osteoblast; MACF1 affecedt the expression of β-catenin and its nuclear translocation. Therefore, under the condition of simulated weightlessness, MACF1 may regulate FOXO1 pathway through β-catenin, affect the redox state of cells, regulate osteoblast differentiation and bone formation. This project intends to study (1) the change of cell oxidative stress, cell differentiation and bone formation under simulated weightlessness condition; (2) the impact of simulated weightlessness condition on the expression of MACF1 and FOXO1, and the interaction between FOXO1 and β-catenin, as well as the transcriptional activity of FOXO1/β-catenin. (3) If MACF1 over-expression could rescue the osteoblast oxidative stress and the inhibitory effect of bone formation by simulated weightlessness conditions. The results of this project will provide a theoretical basis for the clarification and protection of spatial bone loss.

失重抑制骨形成的重要原因之一是引起成骨细胞氧化应激导致成骨分化下降，但作用机制不明。FOXO1在成骨细胞防御氧化应激中尤为重要，需β-catenin参与激活下游基因转录。申请者发现，细胞骨架交联因子MACF1参与成骨细胞抗氧化：模拟失重条件抑制MACF1表达、成骨细胞抗氧化和分化能力下降；MACF1影响β-catenin的表达及入核；MACF1低表达抑制FOXO1激活下游基因转录。因此提出：模拟失重条件下，MACF1可能通过β-catenin，调节FOXO1转录活性，影响细胞抗氧化，调控成骨细胞分化和骨形成。本项目拟研究：模拟失重对⑴骨形成，成骨细胞氧化应激和分化的影响；⑵MACF1与FOXO1表达，FOXO1与β-catenin相互作用和转录活性的影响。⑶MACF1高表达对模拟失重引起成骨细胞氧化应激抑制骨形成的挽救作用及机制。以期为防治空间失重性骨质流失提供理论基础和新靶点

失重导致成骨细胞氧化还原状态失衡、细胞分化能力下降是引起失重性骨质流失的重要原因，然而其机制仍未阐明。FOXO1在前成骨细胞防御氧化应激中起重要作用，需β-catenin参与共激活其下游抗氧化酶的表达。本项目研究发现模拟失重条件可显著升高前成骨细胞内ROS水平，并下调MACF1表达；低表达MACF1的前成骨细胞抗氧化能力下降，分化和矿化能力降低。进一步研究表明，MACF1对β-catenin的表达及核转位有重要调控作用，而β-catenin是FOXO1转录因子发挥转录活性的共激活剂，FOXO1是成骨细胞中维持氧化还原平衡所必须地转录因子。因此，模拟失重条件下，MACF1通过β-catenin，调节FOXO1/β-catenin通路活性，改变细胞氧化还原平衡，调节成骨细胞分化和骨形成。本项目采用已建立的高/低表达MACF1的前成骨细胞模型以及间充质干细胞特异性敲除MACF1的小鼠，在分子、细胞和整体动物水平研究模拟失重或MACF1不同表达水平对成骨细胞氧化还原状态及细胞分化的影响和内在机理，为空间重力性骨质流失机制的阐明和防护提供理论依据。.本项目实施期间，培养青年教师1名，博士后1名，博士研究生2名，硕士研究生1名。该项目成果发表SCI论文11篇，专著1部，申请发明专利3项。