Neuropeptide processing and ischemic retina injury

描述(由申请人提供)：视网膜缺血与许多视网膜疾病有关。神经肽是一类可以调节视网膜对缺血反应的分子。缺血诱导的神经肽表达增加被认为是视网膜的一种内源性保护机制。然而，尽管保护性神经肽表达增加，但为什么仍会发生缺血性视网膜损伤，目前还知之甚少。神经肽最初是作为大的前体合成的，通过一组加工酶的作用被加工成更小的、活性的形式。我们对缺血脑的平行研究表明，脑缺血对关键神经肽加工酶的生物合成激活步骤产生不利影响，导致神经肽前体在缺血脑中积累。神经肽加工酶缺失的动物对缺血应激更敏感。这些发现指导我们研究是否在视网膜中也可能发生类似的缺血诱导的神经肽加工阻断，以及这是否可能是缺血性视网膜损伤的机制。我们对视网膜神经节细胞(RGC)的初步研究结果支持这一观点。对视网膜神经肽加工的分子机制知之甚少。这项建议的具体目的是：1)建立原蛋白转换1和2(分别为PC1和PC2)在视网膜神经肽加工中的潜在参与。这两种关键酶处理大脑中的许多神经肽，包括视网膜中也发现的那些神经肽。在这一目标下的研究包括检测PC1和PC2在视网膜中的存在和发育变化；PC1和PC2在RGC中生物合成激活步骤的特征及其在神经肽加工中的潜在作用；以及对野生型、PC1缺失和PC2缺失小鼠视网膜神经肽图谱的定量蛋白质组学比较。2)采用体内和体外视网膜缺血模型，研究视网膜缺血对PC1和PC2激活步骤和视网膜细胞神经肽产生的影响。PC1基因缺失和PC2基因缺失小鼠对视网膜缺血的反应也将被研究。我们的长期目标是彻底了解视网膜中神经肽的处理过程及其在调节视网膜对损伤应激反应中的作用。最终，这些知识将有助于开发新的治疗策略和治疗视网膜疾病的目标。

DESCRIPTION (provided by applicant): Retinal ischemia has been implicated in a number of retinal disorders. One category of molecules that can regulate the retina's response to ischemia is neuropeptides. An ischemia-induced increase in neuropeptide expression has been considered an endogenous protective mechanism in the retina. It is poorly understood, however, why ischemic retinal injury still occurs regardless of an increased expression in protective neuropeptides. Neuropeptides are initially synthesized as large precursors that are processed into smaller, active forms by the action of a set of processing enzymes. Our parallel studies on ischemic brains have revealed that brain ischemia has an adverse effect on the biosynthetic activation steps of key neuropeptide processing enzymes, resulting in an accumulation of neuropeptide precursors in ischemic brains. Animals null of a neuropeptide processing enzyme are more sensitive to ischemic stress. These findings have directed us to investigate if a similar, ischemia-induced blockade in neuropeptide processing may also occur in the retina, and if this may be a mechanism of ischemic retinal injury. Results of our preliminary studies on retina ganglion cells (RGC) support such notions. Little is known about the molecular mechanisms of neuropeptide processing in the retina. The specific aims of this proposal are: 1) To establish the potential involvement of proprotein converse 1 and 2 (PC1 and PC2, respectively) in retinal neuropeptide processing. These two critical enzymes process many neuropeptides in the brain including those that are also found in the retina. Studies under this aim include examination of the presence and developmental changes of PC1 and PC2 in the retina; characterization of biosynthetic activation steps of PC1 and PC2 in RGC and their potential roles in neuropeptide processing; and a quantitative proteomic comparison of neuropeptide profiles in the retinas of wild type, PC1-null and PC2-null mice. 2) To investigate how retinal ischemia may alter the activation steps of PC1 and PC2 and the production of neuropeptides by retinal cells, using both in vivo and in vitro ischemia models. The response of PC1-null and PC2-null mice to retina ischemia will also be investigated. Our long-term goal is to obtain a thorough understanding of neuropeptide processing in the retina and its role in regulating the retina's response to injurious stresses. Ultimately, such knowledge will help development of new therapeutic strategies and targets for treatment of retinal diseases.