Analyses of retinal circuits after rod rescue in a mouse model of human blindness

项目摘要 视杆感光细胞死亡是人类失明的一个重要原因，许多研究工作已经完成 用于使用基因或干细胞疗法拯救或替代他们。然而，棒状死亡是 其次是视网膜内部的继发性变化，如树突重塑、细胞迁移和重新连接。 这种重组在多大程度上阻碍了光感受器后视力的恢复 目前尚不清楚救援情况。这项建议的目的是检查受影响的视网膜的信号处理。 在基因拯救了杆状病毒之后。为此，我们创造了一种视网膜变性的小鼠模型 由环核苷酸门控(ββ1)通道的CNG亚单位的表达缺失引起的，一个模型 人类常染色体隐性遗传性视网膜色素变性。这一小鼠模型的新颖性在于CNGβ1可以 在他莫昔芬(TX)诱导的Cre-1中，所有受影响的CNGB1-/-杆中内源基因的表达 介导重组，导致杆状拯救。这项提议利用这条鼠标线来确定影响 救援杆在视网膜信号处理中的作用。在目标1中，我们将研究结构和功能是如何 随着CNGβ1表达的恢复，视杆细胞光感受器的表达也随之恢复。我们将特别研究 应用TM对视网膜病变加重的小鼠的功能恢复程度 退化，因为这可能确定杆恢复和进一步停止的效果的关键窗口 退化。在目标2中，我们将研究视杆细胞和它们的主要突触后伙伴之间的突触是如何， 杆状双极细胞，在杆状挽救后进行改造。视杆和视杆双极细胞之间的突触形成视网膜 调节我们夜视的回路。最后，在目标3中，我们将评估杆救援如何影响 视网膜神经节细胞，它是视网膜信号到达高级大脑区域的唯一通道。这个 中心假说是，虽然光敏感度将通过视杆挽救大幅恢复，但视网膜的一些缺陷 由于视网膜回路的继发性变化，信号将在抢救年龄较晚时持续并恶化。这些 研究将确定治疗干预的机会之窗，并为未来提供基础 旨在逆转神经重塑的负面影响的研究。

Project Summary Rod photoreceptor death is a significant cause of human blindness, and much research effort has been expended towards their rescue or replacement using gene or stem cell therapy. However, rod death is followed by secondary changes in the inner retina such as dendritic remodeling, cell migration, and rewiring. The extent to which this reorganization obstructs the potential for recovery of vision following photoreceptor rescue is not known. The objective of this proposal is to examine signal processing in the affected retina following the genetic rescue of rods. To this end, we have created a mouse model of retinal degeneration caused by loss of expression of the β-subunit of the cyclic nucleotide-gated (CNGβ1) channel, a model for autosomal recessive retinitis pigmentosa in humans. The novelty of this mouse model is that CNGβ1 can be expressed from the endogenous locus in all affected CNGB1-/- rods upon tamoxifen(TX)-inducible Cre- mediated recombination, leading to rod rescue. This proposal utilizes this mouse line to determine the impact of rescuing rod function on retinal signal processing. In Aim 1 we will examine how the structure and function of rod photoreceptors recovers following the restoration of CNGβ1 expression. In particular we will examine the extent of functional recovery when TM is administered in mice with increasing severity of retinal degeneration, as this may identify a critical window for the efficacy of rod recovery and halting further degeneration. In Aim 2 we will examine how the synapse between rods and their primary postsynaptic partner, rod bipolar cells, is reformed following rod rescue. Synapses between rods and rod bipolar cells form retinal circuits that regulate our night vision. Finally, in Aim 3 we will evaluate how rod rescue impacts the function of retinal ganglion cells, which are the sole conduit for signals from the retina to reach higher brain areas. The central hypothesis is that while light sensitivity will recover substantially with rod rescue, some deficits in retinal signaling will persist and worsen at late rescue ages due to secondary changes in retinal circuits. These studies will define the window of opportunity for therapeutic intervention and provide a foundation for future studies aimed at reversing the negative effects of neural remodeling.