Role of aquaporins in mammalian lens development,transparency and homeostasis

 描述（由申请人提供）：被称为水通道蛋白（AQP）的跨膜水通道在维持无血管哺乳动物透镜的透明度、生物力学、折射率梯度（RING）和体内平衡方面发挥重要作用。为了获得营养和排除代谢废物，透镜产生了一个涉及AQP、离子和溶质转运蛋白以及共转运蛋白的微循环电流。在正常生理条件下，纤维细胞特异性AQP 0的突变和基因敲除（KO）导致透镜白内障，而上皮细胞特异性AQP 1的突变和基因敲除（KO）不会导致小鼠透镜的任何明显缺陷。然而，AQP 1 KO和AQP 5 KO小鼠的晶状体在高血糖应激条件下发生渗透性肿胀和白内障。几种透镜蛋白如串珠丝蛋白（CP 49和filensin）、晶体蛋白和连接蛋白与AQP 0相互作用，可能调节其功能。本研究的目的是阐明在正常和应激条件下（如糖尿病），AQP 0、AQP 1和AQP 5这三种水通道蛋白在引起和维持透镜透明性、RING和稳态中发挥重要作用的机制。我们的长期目标是为预防和治疗白内障做出贡献。主要假设是：水通道蛋白在透镜微循环、生物力学、RING和RING调节中起关键作用，并且其功能的改变导致白内障。具体目标是：1.探讨是否 为了在体内保持透镜的透明度、生物力学和RING，需要从皮质到核的完整的AQP 0的降低梯度和末端裂解形式的增加梯度的组合。2.测试水渗透性和CTCA功能是否对维持透镜透明度、生物力学和RING至关重要，以及在体外、体内和离体探索AQP 0在透镜纤维细胞之间发挥CTCA的分子机制。3.研究正常和糖尿病高血糖应激条件下，AQP 0、AQP 1和AQP 5的调节是否在维持透镜透明性调节和RING的透明度、生物力学和稳态中起重要作用。将使用结构-功能方法（如适用），并进行显微镜检查、细胞培养、器官培养以及细胞学、生物力学、生物化学、生理学和分子生物学实验，同时沿着开发动物模型。拟议的研究有可能收集重要的数据和关键信息的机制所发挥的作用水通道蛋白在透镜的透明度和稳态。这些结果可以为治疗白内障和其他眼部水通道蛋白相关疾病（如干眼、青光眼、视网膜脱离、黄斑变性和视网膜病变）的新治疗策略提供新的方向。

 DESCRIPTION (provided by applicant): Transmembrane water channels known as aquaporins (AQPs) play significant roles in maintaining transparency, biomechanics, refractive index gradient (RING) and homeostasis in the avascular mammalian lens. To get nourishment and eliminate metabolic wastes, the lens creates a microcirculatory current involving AQPs, ion- and solute transporters, and cotransporters. Mutations in fiber cell-specific AQP0, and knockout (KO) of the gene resulted in lens cataract whereas those of epithelial cell-specific AQP1 did not cause any obvious defects in mouse lens under normal physiological conditions. However, lenses of AQP1 KO and AQP5 KO mice developed osmotic swelling and cataract under hyperglycemic stress conditions. Several lens proteins such as beaded filament proteins (CP49 and filensin), crystallins and connexins interact with AQP0, possibly to modulate its functions. The goal here is to elucidate the mechanisms by which the three AQPs, AQP0, AQP1 and AQP5, play important roles to elicit and maintain lens transparency, RING and homeostasis under normal and stressful conditions (such as diabetes). Our long term objective is to contribute to the prevention and treatment of cataracts. The main hypothesis is: Aquaporins play critical roles in the lens microcirculation, biomechanics, RING and osmoregulation, and alterations in their function(s) lead to cataracts. The Specific Aims are to: 1. To explore whether a combination of a decreasing gradient of intact and an increasing gradient of end cleaved forms of AQP0, from the cortex to the nucleus, is required for maintaining lens transparency, biomechanics and RING in vivo. 2. To test whether both water permeability and CTCA functions are critical for maintaining lens transparency, biomechanics and RING, as well as, to explore in vitro, in vivo and ex vivo the molecular mechanism by which AQP0 exerts CTCA between the lens fiber cells. 3. To investigate if regulation of AQP0, AQP1 and AQP5 plays significant roles in maintaining lens osmoregulation and RING for transparency, biomechanics and homeostasis under normal and diabetic hyperglycemic stress conditions. The objectives will be pursued using structure-function approach, as appropriate, and performing microscopy, cell culture, organ culture as well as cytological, biomechanical, biochemical, physiological, and molecular biological experiments along with developing an animal model. The proposed studies have the potential to gather significant data and key information on the mechanistics of the roles played by AQPs in lens transparency and homeostasis. The results could offer new directions for novel therapeutic strategies for the treatment of cataracts and other aquaporin-related diseases in the eye, such as dry eye, glaucoma, retinal detachment, macular degeneration and retinopathy.