Trace Element Dynamics in the Vertebrate Eye

摘要 铁是正常生理功能的必需元素。然而，过量会导致广泛的 组织损伤并参与许多眼部病理，包括白内障形成和视网膜病变 退化，如年龄相关性黄斑变性。眼铁代谢的研究一直是一个热点 多年来一直是这个实验室的焦点。我们最近对铁的生理作用进行了新的观察， 作用我们发现，铁调节神经递质谷氨酸的合成和分泌， 组织和神经元。这是基本的临床相关性，因为铁和谷氨酸都是 在神经退行性疾病中失调。大量的谷氨酸盐在中枢神经系统中具有兴奋性毒性， 系统以及视网膜。此外，在视网膜色素上皮细胞（RPE）和透镜上皮细胞中， (LEC)铁调节转录因子低氧诱导因子的活性，低氧诱导因子反过来调节 几十种蛋白质的合成我们的初步数据表明，缺氧条件下刺激 谷氨酸释放，另一个至关重要的观察，因为缺氧条件发生在中风， 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 随着年龄增长、白内障发生和分化而发生的晶状体。我们将继续探讨这些 这些变化影响铁蛋白中的铁储存以及这种储存提供的对铁损伤的保护。 不幸的是，人们对与眼睛隔离的眼睛中铁水平如何调节知之甚少 血眼屏障（BOB）。该提案的假设是，眼内组织 具有独特的和独立的系统，用于调节穿过眼睛的铁吸收和从眼睛流出。 鲍勃它们在眼组织内的极化位置和铁调节量允许适当地控制 眼内铁水平。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学中起关键作用。 我们将使用一种创新的综合方法来确定BOB如何调节铁水平， 眼内组织这两个特定的目标利用正常和病态的人眼以及正常的 犬眼和形成BOB的细胞的组织培养物，例如，RPE和CE。另外，透镜将 用于评估铁处理策略如何适应在正常缺氧环境中的生存。我们 将利用最先进的活细胞成像定量荧光显微镜， 用于定量质膜处的事件的反射荧光，并允许测量 这些复杂的相互作用在活细胞的四维（4D）的基础上的动态过程。是 本提案的目的是确定如何控制眼内铁水平以及铁的具体作用 在眼科病理学中的作用，以便为开发治疗方法提供基础， 预防和治疗眼部疾病。

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.