Trace Element Dynamics in the Vertebrate Eye

摘要 铁是正常生理功能所必需的元素。然而，过量的它会导致广泛的 组织损伤并参与多种眼部病理，包括白内障和视网膜 老年性黄斑变性等退行性病变。眼部铁代谢的研究一直是一个 多年来一直是这个实验室的重点。我们最近对铁的生理特性进行了新的观察 角色。我们发现，铁通过眼睛调节神经递质谷氨酸的合成和分泌 组织和神经元。这具有基本的临床意义，因为铁和谷氨酸都 神经退行性变中的失调。大量的谷氨酸对中枢神经系统有兴奋性毒性作用。 系统和视网膜也一样。此外，视网膜色素上皮细胞(RPE)和晶状体上皮细胞 (LEC)铁调节转录因子低氧诱导因子的活性，而低氧诱导因子又调节转录因子 几十种蛋白质的合成。我们的初步数据表明，低氧条件会刺激 谷氨酸释放，另一个至关重要的观察结果，因为低氧条件发生在中风和 视网膜缺血。此外，铁储存蛋白铁蛋白的结构也发生了深刻的变化 随着年龄、白内障的发生和分化而发生的晶状体中。我们将继续探索这些 变化会影响铁蛋白中的铁存储，以及这种存储提供的对铁损害的保护。 不幸的是，对于眼睛中铁的水平是如何调节的，我们知之甚少。 血眼屏障的体循环(BOB)。该提案的假设是眼内组织 有独特和独立的系统来调节眼睛对铁的吸收和流出 鲍勃。它们在眼组织中的极化位置和铁调节量允许适当地控制 眼内铁含量。缺氧、出血和炎症显著影响铁摄取储存， 利用和流出。由此导致的铁代谢失调在眼部病理中起着至关重要的作用。 我们将使用一种创新的综合方法来确定鲍勃如何调节体内的铁水平 眼内组织。这两个特定的目标利用了正常和病理的人眼以及正常的 犬眼和形成BOBS的细胞的组织培养，例如RPE和CE。此外，该镜头将 用于评估铁处理策略如何适应在正常低氧环境中的生存。我们 将使用最先进的活细胞成像定量荧光显微镜， 用于量化质膜上的事件的反射荧光并允许测量 活细胞中四个维度(4D)的这些复杂相互作用背后的动态过程。它是 这项建议的目标是确定如何控制眼内铁水平以及铁的具体作用(S) 在眼部病理学方面，以便为开发所需的治疗方式提供基础 眼科疾病的防治。

Abstract Iron is an essential element for normal physiological functions. However, excess it can cause extensive tissue damage and participates in numerous ocular pathologies including cataractogenesis and retinal degenerations such as age-related macular degeneration. The study of ocular iron metabolism has been a focus of this laboratory for many years. We have made recent novel observations about iron's physiological role. We found that iron regulates synthesis and secretion of the neurotransmitter glutamate by ocular tissues and neurons. This is of fundamental clinical relevance since iron and glutamate are both dysregulated in neurodegeneration. In high quantities, glutamate can be excitotoxic in the central nervous system as well as the retina. Additionally, in retinal pigmented epithelial cells (RPE) and lens epithelial cells (LEC) iron regulates the activity of the transcription factor, hypoxia-inducible factor, which in turn regulates the synthesis of dozens of proteins. Our preliminary data indicate that hypoxic conditions stimulate glutamate release, another critically important observation since hypoxic conditions occur in stroke and retinal ischemia. Furthermore, there are profound changes in the structure of the iron storage protein ferritin in lenses that occur with age, cataractogenesis and differentiation. We will continue to explore how these changes affect iron storage in ferritin and the protection against iron damage such storage provides. Unfortunately, little is known about how iron levels are regulated in the eye which is isolated from the systemic circulation by blood ocular barriers (BOB). The proposal's hypothesis is that intraocular tissues have unique and independent systems for regulating iron uptake into and efflux from the eye across the BOBs. Their polarized location and iron-regulated quantity within ocular tissues allows for proper control of intraocular iron levels. Hypoxia, hemorrhage and inflammation significantly impact iron uptake storage, utilization and efflux. The resulting dysregulation of iron metabolism plays a critical role in ocular pathology. We will use an innovative integrated approach to determine how the BOB's regulate iron levels in intraocular tissues. The two specific aims utilize normal and pathological human eyes as well as normal canine eyes and tissue cultures of cells which form the BOBs, e.g., RPE and CE. Additionally, the lens will be used to assess how iron handling strategies adapt for survival in a normally hypoxic environment. We will utilize a state-of-the-art live-cell imaging quantitative fluorescence microscope with total internal reflection fluorescence for quantifying events at the plasma membrane and allow for measurement of dynamic processes underlying these complex interactions in four dimensions (4D) in living cells. It is the goal of this proposal to determine how intraocular iron levels are controlled and the specific role(s) iron has in ocular pathology in order to provide a basis for development of therapeutic modalities needed for prevention and treatment of ocular disease.