Sigma 1 Receptor: a novel therapeutic target for retinal degeneration

项目总结 失明的视网膜病变构成了一种迫切的未得到满足的医疗需求，需要新的治疗策略。 视网膜退行性疾病是全世界无法治愈的失明的主要原因，并经常涉及 感光细胞(PRC)死亡。最近，我们报道了锥体PRC功能的戏剧性救援 Pde6brd10/J(Rd10)小鼠视网膜病变模型的建立 PTz)，Sigma-1受体(σ-1R)的高亲和力配体。σ1R是一种跨膜蛋白，被认为是 分子伴侣参与内质网应激反应。研究支持σ1R调节内质网的观点 视网膜中的应激和钙信号。然而，新的数据显示，σ1R也定位于核膜 几种视网膜细胞类型(RGC、PRC和Müller细胞)的研究表明，内质网应激的减弱可能不 全面解释σ1R介导视网膜神经保护的机制(S)。我们假设一部小说 σ1R激活提供强大的视网膜神经保护作用的机制是调节NRF2- Keap1途径。NRF2可以说是细胞中最重要的抗氧化分子，因为它调节 转录500多个抗氧化剂/细胞保护基因。在没有压力的情况下，Nrf2保留在 由Keap1和过量的Nrf2形成的细胞质被蛋白酶体降解。然而，在细胞压力下， Keap1释放Nrf2，然后Nrf2移位到细胞核，激活‘抗氧化反应元件’(ARE) 编码大量细胞防御蛋白和酶的基因。氧化应激是一种主要的致病因素 PRC退变的潜在因素。显著增加(+)-pTZ与σ1R的结合。我们知道(+)-PTZ RD10小鼠的治疗调节视网膜Nrf2水平、抗氧化基因表达和蛋白质/脂 然而，我们不知道Nrf2是否是这些视网膜神经保护作用的核心。目标1 将通过评估NRF2对RD10 PRC救援的充分和必要程度来测试这一点。我们知道 在原代Müler细胞中，σ1R与NRF2-Keap1在功能上相互作用，但我们不知道到什么程度 它改变了通路中蛋白质的功能或与之相互作用。目标2将通过评估范围来测试这一点 其中(+)-PTZ治疗改变了Nrf2-Keap1基因/蛋白的表达，Nrf2核转位，Nrf2 WT和σ1R-/-Müler细胞的激活、Keap1抑制和NRF2蛋白酶体降解，并将评估 σ1R与NRF2-Keap1通路成员的相互作用。最后，我们知道(+)-PTZ可以拯救锥体PRC 在rd10小鼠中，直到出生后42天；然而，我们不知道(+)-PTZ治疗能在多大程度上 推迟超过这个年龄的RD10小鼠的锥体死亡，也不知道这种影响是否可以推广到其他σ1R配体。 目标3将通过延长时间评估(+)-PTZ治疗的rd10小鼠的视网膜功能/结构来测试这一点 并将评估另外两个σ1R配体的疗效。总之，前景看好的数据构成了我们 该提案探索了一种新的机制，即σ1R激活通过调解中华人民共和国的救援和调查 这种现象在多大程度上是可持续的，并可推广到其他σ1R配体。

PROJECT SUMMARY Blinding retinopathies constitute an urgent unmet healthcare need demanding novel therapeutic strategies. Retinal degenerative diseases are the major cause of untreatable blindness worldwide and frequently involve photoreceptor cell (PRC) death. Recently, we reported dramatic rescue of cone PRC function in the Pde6brd10/J (rd10) mouse model of retinopathy when mice were treated systemically with (+)-pentazocine ((+)- PTZ), a high affinity ligand for sigma 1 receptor (σ1R). σ1R is a transmembrane protein considered a molecular chaperone involved in the ER stress response. Studies support the notion that σ1R modulates ER stress and Ca2+ signaling in retina. However, new data show that σ1R localizes also to the nuclear membrane of several retinal cell types (RGC, PRC, and Müller cells) suggesting that attenuation of ER stress may not explain entirely the mechanism(s) by which σ1R mediates retinal neuroprotection. We postulate that a novel mechanism underlying the robust retinal neuroprotection afforded by σ1R activation is modulation of the Nrf2- Keap1 pathway. Nrf2 is arguably the most important antioxidant molecule in cells because it regulates transcription of more than 500 antioxidant/cytoprotective genes. In the absence of stress, Nrf2 is retained in the cytoplasm by Keap1 and excess Nrf2 is degraded by the proteasome. However, under cellular stress, Keap1 releases Nrf2, which then translocates to the nucleus to activate ‘antioxidant response elements’ (ARE) of genes that encode numerous cell defense proteins and enzymes. Oxidative stress is a major pathogenic factor underlying PRC degeneration. It significantly increases binding of (+)-PTZ to σ1R. We know that (+)-PTZ treatment of rd10 mice modulates retinal Nrf2 levels, antioxidant gene expression and protein/lipid peroxidation, however we do not know whether Nrf2 is central to these retinal neuroprotective effects. Aim 1 will test this by evaluating the extent to which Nrf2 is sufficient and essential to rd10 PRC rescue. We know that σ1R interacts functionally with Nrf2-Keap1 in primary Müller cells; however we do not know the extent to which it alters function of or interacts with proteins in the pathway. Aim 2 will test this by evaluating the extent to which (+)-PTZ treatment alters Nrf2-Keap1 gene/protein expression, Nrf2 nuclear translocation, Nrf2 ARE activation, Keap1 inhibition, and Nrf2 proteasomal degradation in WT and σ1R-/- Müller cells and will evaluate σ1R interaction with members of the Nrf2-Keap1 pathway. Finally, we know that (+)-PTZ can rescue cone PRC in rd10 mice through post-natal day (P)42; however we do not know the extent to which (+)-PTZ treatment can delay cone death in rd10 mice beyond this age nor whether the effects are generalizable to other σ1R ligands. Aim 3 will test this by evaluating retinal function/structure in (+)-PTZ-treated rd10 mice over an extended time course and will assess efficacy of two other σ1R ligands. In summary, promising data form the basis of our proposal, which explores a novel mechanism by which σ1R activation mediates PRC rescue and investigates the extent to which the phenomenon is sustainable and generalizable to other σ1R ligands.