Intercellular communication in the lens

描述（由申请人提供）：出生后晶状体生长和透明需要连接蛋白通道提供间隙连接通信。编码Cx46和Cx50基因的靶向缺失会导致小鼠白内障。同样，Cx50和Cx46基因的突变在人类和小鼠中都会导致多种白内障类型。偶联的改变被认为是糖尿病和老年白内障发生的基础，但很少有研究直接将间隙连接偶联与这些病理生理条件联系起来。最近，我们发现由Cx46、Cx50和Cx43组成的通道的分子渗透性存在差异。在本研究中，我们将继续进行电生理研究，以了解连接蛋白形成的通道类型的多样性如何影响晶状体功能，以及它们的改变如何导致先天性和年龄相关性白内障。在Aim 1中，我们将确定晶状体中Cx46和Cx50间隙连接提供的耦合在维持内纤维细胞中重要代谢物的足够浓度方面的重要性。我们将使用电生理和生化分析来研究分子在体外和体内的渗透。我们还将确定导致先天性白内障的Cx50和Cx46突变是否具有分子通透性的改变。其次，我们将确定耦合电导和/或渗透率是否随着老化和氧化应激而改变。质谱方法将被用于识别老化和白内障发生过程中连接蛋白的修饰。修改对间隙连接的电导和渗透率的影响将使用电生理学方法进行评估。

DESCRIPTION (provided by applicant): Gap junctional communication provided by connexin channels is required for postnatal lens growth and transparency. Targeted deletions of genes encoding Cx46 and Cx50 lead to cataracts in mice. Similarly, mutations in both Cx50 and Cx46 genes cause a variety of cataract types in both humans and mice. Alterations in coupling have been suggested to underlie cataracts that occur with diabetes and with age, but there are few studies directly linking gap junctional coupling to these pathophysiological conditions. More recently, we found that there are differences in the molecular permeability through channels made of Cx46, Cx50 and Cx43. In this proposal, we will continue to pursue electrophysiological studies to understand how the diversity in channel types formed by connexin proteins influences lens function and how their alteration leads to congenital and age-related cataracts by pursuing the following two Aims. In Aim 1, we will determine the importance of coupling provided by Cx46 and Cx50 gap junctions in the lens in the maintenance of adequate concentrations of important metabolites in inner fiber cells. We will use electrophysiological and biochemical assays to study the permeation of molecules in vitro and in vivo. We will also determine whether Cx50 and Cx46 mutations that cause congenital cataracts have alterations in molecular permeability. Second, we will determine whether coupling conductance and/or permeability is altered with aging and oxidative stress. Mass spectrometric methods will be employed to identify modifications to connexins with aging and during cataractogenesis. The effect of modifications on conductance and permeability of gap junctions will be assessed using electrophysiological methods. PUBLIC HEALTH RELEVANCE: Communication between cells is mediated by proteins called connexins. Mutations in these connexin proteins are responsible for a number of diseases in humans, including cataracts, the leading cause of blindness in the world. Our studies are aimed at understanding the importance of these proteins in both age-onset and congenital cataracts.