TRF2通过端粒外效应激活Wnt通路调节Müller细胞重编程抑制感光细胞退行性改变的作用机理研究

TRF2 is an essential protein required for telomeres protection, which plays a vital role in regulating gene expression through extratelomeric effect. In the present study, we found that TRF2 deficiency induce photoreceptor degeneration and decreased regeneration in TRF2+/- zebrafish. However, the underlying mechanisms remain elusive. Next generation sequencing (NGS) revealed that the expression of genes associated with cell reprogramming are significantly changed in the Müller glia cells of TRF2+/- zebrafish retina. Müller glia cells possess potential neurogenic properties, It is well known that Müller cells is an important participant in retinal repair photoreceptor cells (RRPCs), we speculate that the injured photoreceptor cells can be repaired via Müller cells reprogramming and this reprogramming is regulated by TRF2 controlled extra-telomeric roles. The study proposed above may illuminate the impact of dysfunction of Müller glia cells on photoreceptor degeneration and clarify how TRF2 modulates Müller glia function, which could expose new insights into the mechanism underlying Müller glia reprogramming and identify novel targets and pathways to prevention and treatment of photoreceptor degeneration.

TRF2是端粒保护蛋白，可通过端粒外效应调控基因表达。申请人首次发现TRF2+/-斑马鱼感光细胞退行性改变且视网膜再生能力下降，机制不清。二代测序发现，TRF2+/-斑马鱼Müller细胞重编程相关基因表达改变。Müller细胞是视网膜再生的主力军，可抑制感光细胞退行性改变，故此我们推测TRF2可通过端粒外效应调控Müller细胞功能，抑制感光细胞退行性改变。课题通过多种手段观察TRF2+/-斑马鱼Müller细胞重编程的改变；通过RNA Seq、ChIP Seq及单细胞测序探讨TRF2对Müller细胞功能的调控机制及具体靶点，明确Müller细胞抑制感光细胞退行性改变的重要机理，阐明TRF2调控Müller细胞重编程的具体机制。课题的完成将加深对Müller细胞调控网络的理解，有助于发现干预感光细胞退行性改变的新靶点，也将丰富对TRF2端粒外效应的认识，对理解全身衰老机制有着深远意义。

衰老相关分泌表型（Senescence Associated Secretory Phenotype, SASP）,是衰老的重要标志之一，可导致组织、机体慢性低度炎症和疾病，并且可加速周围细胞衰老进程。项目负责人前期研究已证明，SASP在视网膜退行性疾病中起着重要作用。因此，在本项目中，TRF2敲低后斑马鱼出现视网膜退行性改变，并且该表型无法被P53敲除所缓解；进一步，RNA Sequencing研究结果显示，TRF2敲低后视网膜退行性改变可能与视网膜炎症微环境有关。并且，小鼠激光诱导脉络膜新生血管（Choroidal Neovascularization,CNV）模型中也可表现出视网膜退行性改变，RNA Sequencing结果显示，其主要通过激活STAT3后上调IL17通路，诱导炎症因子分泌，重要的是，白杨素可以有效缓解端粒损伤，从而抑制SASP，下调相关通路抑制CNV的形成，缓解视网膜退行性改变。此外，本项目尝试探索有效抑制CNV的潜在治疗措施，证实聚乙二醇-聚阳离子高分子纳米递送材料可成功递送sFlt-1基因，抑制新生血管形成，为后续通过基因治疗策略修复视网膜退行性改变奠定基础。.综上，本项目通过对TRF2+/-斑马鱼及激光诱导CNV小鼠模型的观察，证实视网膜退行性病变的发病机制与SASP导致的视网膜炎症微环境密切相关。并且，端粒功能衰退是视网膜炎症微环境的重要扳机点。其中，端粒相关蛋白TRF2对于维持端粒功能正常有着重要作用，可通过端粒外效应调控SASP相关炎症因子的表达。此外，研究发现，聚乙二醇-聚阳离子高分子纳米递送系统可针对视网膜成功实现基因递送，对于今后以端粒为靶点治疗视网膜退行性病变奠定基础。