POU4F2和ISL1转录因子在青光眼中的保护功能

Optic nerve diseases such as glaucoma are a family of eye diseases that cause the degeneration of retinal ganglion cells (RGCs) and eventually lead to blindness. Currently, the underlying molecular mechanism of RGC death in optic nerve diseases is poorly understood. Previously, we have shown that all three POU4F family genes, Pou4f1, Pou4f2, and Pou4f3, are essential for neuronal survival. Targeted deletion of each of the Pou4f genes leads to a common phenotype of neuronal death by apoptosis in various nervous systems. In retina, loss of Pou4f2 results in the apoptosis of a majority of RGCs during embryonic development. We have also shown that Isl1 is required for RGC survival and that ISL1 and POU4F2 act synergistically during RGC development. Though POU4F2 and ISL1 are expressed in adult RGCs, their roles remains largely unexplored. Here, we hypothesize that POU4F2 and ISL1 are essential factors for the survival of adult RGCs and loss of Pou4f2 and Isl1 will result in RGC death by apoptosis. To investigate the role of Pou4f2 and Isl1 in RGC survival, we propose: 1) To determine the essential role of Pou4f2 and Isl1 in the survival of adult RGCs by conditional removal of Pou4f2 and Isl1 in adult RGCs and to investigate whether the removal of Pou4f2 and Isl1 results in RGC death. 2) To determine the protective roles of Pou4f2 and Isl1, we will over-express Pou4f2 and Isl1 in adult RGCs of mouse glaucoma models and determine whether the over-expression of Pou4f2 and Isl1 will prevent or delay RGC apoptosis in these mice.

包括青光眼在内的视神经疾病是视弱及失明的最主要病因之一，这类视神经疾病都是由于视网膜神经节细胞（retinal ganglion cells，RGCs）死亡及其神经纤维缺失而产生。视神经疾病的病因比较复杂，受多种遗传及环境因素的影响。 我们过去的研究表明Pou4f2和Isl1转录因子在RGCs的早期发育及存活过程中起着关键作用；我们同时还发现Pou4f2和Isl1的表达在RGCs丧失起始前均下调，提示Pou4f2和Isl1可能为成体RGCs存活所必需，下调Pou4f2和（或）Isl1的表达将诱发RGCs的凋亡。本项目拟采用转基因与基因敲除小鼠及青光眼小鼠模型，在已明确Pou4f2和Isl1对RGCs的存活有作用的基础上，进一步研究小鼠青光眼模型中Pou4f2和Isl1表达改变对RGCs生存的影响，探索青光眼中RGCs损伤的机制，为此类眼病的预防、早期诊断和基因治疗奠定基础。

青光眼是全球第二大不可逆性的致盲眼病，包括青光眼在内的视神经疾病是视弱及失明的最主要病因之一，这类视神经疾病都是由于视网膜神经节细胞（retinal ganglion cells，RGCs）死亡及其神经纤维缺失而产生。但迄今为止，小鼠青光眼模型及转基因与基因敲除技术在转录因子对RGCs影响的研究，及在转录因子作为青光眼早期诊断基因和治疗的靶向基因的研究甚少。我们及其他研究者已发现Pou4f2和Isl1转录因子在RGCs的存活和发育中起着至关重要的作用。本项目拟采用转基因与基因敲除小鼠及小鼠青光眼模型，在已明确Pou4f2和Isl1对RGCs正常发育、存活有作用的基础上，进一步研究小鼠青光眼模型中Pou4f2和Isl1表达的改变对RGCs存活的影响，探索青光眼发生过程中RGCs的损伤机制，以为此类眼病的预防、早期诊断和基因治疗提供理论依据。我们在研究开展中发现Pou4f2和Isl1并未在青光眼眼模型中对RGCs有保护作用，故随后我们探索了其他转录因子在青光眼RGCs损伤的机制中的作用，并发现潜在因子sox4和sox11。在随后的研究中，我们首先条件性在小鼠视网膜中敲除Sox4,Sox11及Sox4和Sox11。Sox4或Sox11的单基因敲除分别导致部分视网膜神经节细胞的减少；然而，Sox4/Sox11的双敲除却导致视网膜神经节细胞完全丧失，从而证实的Sox4和Sox11的功能冗余，共同调节早期胚胎阶段视网膜神经节细胞的产生，并在视网膜神经节细胞在胚胎发育后期阶段的生存以及青光眼RGCs损伤机制中发挥作用。这项研究阐明了Sox4和Sox11是RGCs发育必不可少的基因，增进了我们对RGCs分化和视网膜发育调控网络的理解，对视神经发育和RGCs再生研究有重要的促进作用。