转录因子MITF对视网膜氧化损伤的保护作用及机制研究

Retinal oxidative damage is closely related to various retinal diseases, including AMD. The antioxidant system of RPE cell is essential in counterbalancing the high oxidative stress in the neural retina, although the precise mechanism has not been fully understood. Our previous works found that the oxidative damage of retinal cells in Mitf defective mice was significantly aggravated, while the antioxidant ability of MITF high expression RPE cell line was evidently increased and the degree of retinal oxidative damage was dramatically reduced in the overexpression of MITF transgenic mice. Based on the preliminary studies, we hypothesized that high expression of MITF in RPE cells can promote the antioxidant of RPE cells and hence protect the retina from oxidative damage. In this proposal, we plan to use Mitf defeciency and overexpression transgenic mice to investigate the functional roles and protective molecular mechanisms of MITF in the retinal oxidative damage through three different retinal oxidative damage models. We believe that this proposal can elucidate the regulatory mechanism of "MITF-downstream target gene-RPE antioxidant-retinal oxidative damage protection" and explore a new effective way to slow down the progression of retinal oxidative damage in mice. We expect the outcomes from this project will provide insights to deep understanding of the underlying molecular and cellular mechanisms of the oxidative damage-related retinal degeneration and a prospective and experimental basis for the translational medical research of retinal oxidative damage.

视网膜氧化损伤与AMD等多种视网膜病变的发生密切相关。RPE细胞的抗氧化能力与视网膜氧化应激平衡状态的维持密切相关，但其调控机制未明。在前期工作中，我们发现Mitf功能缺失小鼠视网膜氧化损伤显著加剧，而高表达MITF的RPE细胞系抗氧化能力显著增强，在体高表达MITF的转基因小鼠视网膜氧化损伤程度明显减轻。故此，我们提出假说：在RPE细胞中高表达MITF可以促进RPE细胞的抗氧化功能进而保护视网膜抵御氧化损伤。在本项目中，我们拟利用Mitf功能缺失与高表达转基因小鼠，通过三种视网膜氧化损伤模型对MITF在视网膜氧化损伤中的保护功能及其分子机制开展相关研究。通过本项目研究，我们期待可以解析“MITF-下游靶基因-RPE抗氧化-视网膜氧化损伤保护”的机制和调控规律，并探寻可以减缓小鼠视网膜氧化损伤的方法。通过本项目的实施，我们期望为保护视网膜氧化损伤的转化医学研究提供前瞻性思路和实验依据。

视网膜氧化损伤与年龄相关性黄斑变性（AMD）等多种视网膜病变的发生密切相关。RPE细胞的抗氧化能力与视网膜氧化应激平衡状态的维持密切相关，但其调控机制未明。在本项目中，我们研究发现RPE细胞关键转录因子MITF在RPE细胞的抗氧化调控中起着重要的作用。本项目研究结果显示MITF在RPE细胞中能够同时、直接调控细胞抗氧化调控的两个核心因子PGC1a和NRF2，并且通过调控PGC1a-P62通路促进NRF2的入核，并以此在RPE细胞抗氧化功能中发挥强大的调控作用。之后，我们利用Mitf基因缺陷和Dct-Mitf高表达小鼠，通过视网膜碘酸钠损伤、视网膜光损伤和视网膜高氧损伤等模型，研究明确了MITF通过促进RPE细胞抗氧化能够在体保护视网膜抵御氧化损伤。在此基础上，我们利用RPE细胞特异性的AAV9-p.RPE65-MITF基因治疗的方式证明了RPE细胞特异性高表达MITF能够有效保护视网膜抵御氧化损伤。最后，我们还进一步揭示了DAPL1是RPE细胞中一个上游调控因子，进一步丰富了该领域的研究并为后续的研究工作打开了更宽广的思路。