Lens intercellular communication connexins and cataract

描述（由申请人提供）：连接蛋白是间隙连接的亚基蛋白，它允许离子、第二信使和小代谢物通过细胞间通道在相邻细胞之间交换。晶状体连接蛋白基因的突变可导致人类和小鼠的白内障和发育缺陷，晶状体连接蛋白的间隙连接通讯在晶状体的发育和维持中起着重要的作用。信号转导通路也被证明在晶状体发育和体内平衡中起关键作用，信号基因如磷酸酶和紧张素同源物（PTEN）的突变导致包括白内障在内的复杂的人类综合征疾病。尽管已经取得了很大的进展，但我们对这两种不同的细胞间通信系统之间潜在合作的了解仍然存在很大的差距。在这个提议中，我们的目标是进一步定义晶状体中间隙连接通信如何与其他细胞间信号转导途径相互作用。我们建议首先通过生成和表征晶状体中缺乏PI3K的p110a和p110b催化亚基的条件敲除小鼠来研究PI3K缺乏的后果。其次，我们将制造晶状体中缺乏PTEN的条件敲除小鼠，并检测其表型。最后，我们将通过药物阻滞剂、电生理测量和体外生化分析来研究晶状体间隙连接耦合与PI3K/Akt和PTEN信号通路在出生后生长和体内平衡中的相互作用。我们还将PI3K和PTEN条件敲除动物与连接蛋白敲除小鼠杂交，以确认体内相互作用。这些研究将通过体外药理学和电生理分析与体内动物模型相结合，深入了解间隙连接耦合和信号转导途径如何协同相互作用，调节晶状体生长和体内平衡。他们还将拓宽关于细胞间通讯的综合系统如何促进许多组织发育调节的一般范例。

DESCRIPTION (provided by applicant): Connexins are the subunit proteins of gap junctions, which allow the exchange of ions, second messengers and small metabolites between adjacent cells through intercellular channels. Gap junctional communication is important in the development and maintenance of lens, as mutations in lens connexin genes cause cataract and developmental defects in humans and mice. Signal transduction pathways have also been shown to play critical roles in lens development and homeostasis, and mutations in signaling genes like phosphatase and tensin homolog (PTEN) cause complex human syndromic disorders that include cataract. Although great progress has been made, there are still substantial gaps in our knowledge about potential cooperation between these two different intercellular communication systems. In this proposal, our objective is to further define how gap junctional communication interacts with other intercellular signal transduction pathways in the lens. We propose first to examine the consequences of PI3K deficiency by generating and characterizing conditional knockout mice lacking the p110a and p110b catalytic subunits of PI3K in the lens. Second, we will make conditional knockout mice lacking PTEN in the lens, and examine their phenotype. Finally, we will investigate interactions between lens gap junctional coupling and the PI3K/Akt and PTEN signaling pathways in postnatal growth and homeostasis by using pharmacological blockers, electrophysiological measurements and biochemical assays in vitro. We will also cross PI3K and PTEN conditional knockout animals with connexin knockout mice to confirm interactions in vivo. These studies will provide insights into how gap junctional coupling and signal transduction pathways synergistically interact to regulate lens growth and homeostasis by combining in vitro pharmacological and electrophysiological assays with in vivo animal models. They also will broaden the general paradigm of how an integrated system of intercellular communication contributes to the regulation of development in many tissues.