Lens intercellular communication connexins and cataract

描述（由申请方提供）：连接蛋白是间隙连接的亚单位蛋白，允许相邻细胞之间通过细胞间通道交换离子、第二信使和小代谢物。间隙连接通讯在透镜的发育和维持中是重要的，因为透镜连接蛋白基因的突变在人类和小鼠中引起白内障和发育缺陷。信号转导途径也已被证明在透镜发育和体内平衡中起关键作用，并且信号传导基因如磷酸酶和张力蛋白同源物（PTEN）的突变引起包括白内障在内的复杂的人类综合征病症。虽然已经取得了很大的进展，仍然有很大的差距，我们的知识这两个不同的细胞间通信系统之间的潜在合作。在这个提议中，我们的目标是进一步确定间隙连接通讯如何与其他细胞间的信号转导通路在透镜相互作用。我们建议首先检查PI 3 K缺乏的后果，通过产生和表征条件性敲除小鼠缺乏PI 3 K的p110 a和p110 b催化亚基的透镜。第二，我们将制造透镜中缺乏PTEN的条件性敲除小鼠，并检查它们的表型。最后，我们将研究透镜间隙连接耦合和PI 3 K/Akt和PTEN信号通路在出生后的生长和稳态之间的相互作用，通过使用药理学阻断剂，电生理测量和体外生化测定。我们还将PI 3 K和PTEN条件性敲除动物与连接蛋白敲除小鼠杂交以确认体内相互作用。这些研究将通过结合体外药理学和电生理学测定与体内动物模型，深入了解间隙连接偶联和信号转导途径如何协同相互作用以调节透镜生长和体内平衡。它们还将拓宽细胞间通讯的综合系统如何有助于许多组织发育调控的一般范式。 公共卫生相关性：连接蛋白基因的突变会导致人类和小鼠的广泛健康问题，包括白内障和眼部发育缺陷。磷酸酶和张力蛋白同源物（PTEN）的突变引起包括白内障在内的复杂的人类综合征疾病。遗传学研究已经揭示了许多关于白内障引起这些不同基因突变的信息，但是我们对这两种不同细胞间通讯系统在预防正常透镜白内障中的潜在合作的认识仍然存在很大的差距。拟议的研究将进一步表征这些导致先天性白内障的基因，并进一步表征通过整合通讯途径对透镜上皮细胞周期的控制。

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. PUBLIC HEALTH RELEVANCE: Mutations in connexin genes cause a broad spectrum of human health problems including cataract and ocular developmental defects in humans and mice. Mutations in phosphatase and tensin homolog (PTEN) cause a complex human syndromic disorder that includes cataract. Genetic studies have revealed much about cataract causing mutations in these different genes, but there are still substantial gaps in our knowledge about potential cooperation between these two different intercellular communication systems in preventing cataract in the normal lens. The proposed studies will further characterize these genes that cause congenital cataract, and also further characterize the control of the cell cycle in lens epithelia by integrated communication pathways.