Glial Signaling:Interplay of Connexins and P2 Receptors

描述（由申请人提供）：星形胶质细胞相互通信 通过Ca +2的传播波。 活动并与神经元相互作用。该机制负责 星形胶质细胞之间的细胞间钙波的传播涉及两个 平行的通路，一个依赖于缝隙连接，一个依赖于缝隙连接， junction独立对于间隙连接介导的钙波传播， 第二信使扩散，如1P3、Ca2+和/或环ADP-核糖 跨越细胞边界是维持再生事件的关键。通过 相反，差距连接独立机制依赖于细胞外的 嘌呤和嘧啶从一个细胞中释放出来， 附近细胞膜上的P2受体。我们最近获得了 来自Cx43缺失小鼠的星形胶质细胞显示不同功能的P2Y的证据 与野生型小鼠的星形胶质细胞相比， 嘌呤受体亚型表达的转换可以显著影响 钙波通过细胞外空间传播。这些结果 从而导致整体假设，嘌呤受体和缝隙连接 通道在功能上是相关的，Cx43调节这两种模式， 星形胶质细胞之间相互交流。有可能不同的 由不同连接蛋白形成的缝隙连接的选择性渗透性， 连接复合物的重塑通过某些结构域介导， 连接蛋白参与连接蛋白和P2Y受体之间的相互作用。到 为了验证这些假设，我们将上调和下调Cx43的表达水平， 和其他间隙连接蛋白，并测量功能和表达的变化， P2Y受体亚型在存在和不存在间隙连接通道的情况下 阻滞剂。为了评估连接蛋白和表达之间的相互作用， P2Y受体是由corexins的特定结构域介导的，我们将表达 Cx43缺乏SH2/SH3或PDZ序列，并测试功能变化， P2Y受体亚型的表达。 细胞间通讯将通过测量 钙波传播和耦合强度。预计到 阐明星形胶质细胞中缝隙连接和P2受体之间的相互作用， 为了描述细胞间通信，将公开 规定了长距离小区到小区信号传输的范围 在CNS中。

DESCRIPTION (provided by applicant): Astrocytes communicate with one another through propagated waves of Ca+2 .signaling both to coordinate their own activity and to interact with neurons. The mechanism responsible for the propagation of intercellular calcium waves between astrocytes involved two parallel pathways, one dependent on gap junctions and one that is gap junction-independent. For gap junction-mediated calcium wave propagation, diffusion of second messengers, such as 1P3, Ca2+, and/or cyclic ADP-ribose across cell boundaries is critical to sustain the regenerative event. By contrast, the gap junction-independent mechanism relies on the extracellular diffusion ofpurines and pyrimidmes released from one cell which then activates P2 receptors on the membranes of nearby cells. We have recently obtained evidence that astrocytes from Cx43 null mice display a different functional P2Y subtype expression compared to astrocytes from wildtype mice aTrd that this switch in purinoceptor subtype expression can markedly affect the extent to which calcium waves propagate through the extracellular space. These results thus lead to the overall hypothesis that purinoceptors and gap junction channels are functionally related, and that Cx43 regulates both modes by which astrocytes communicate with one another. It is possible that different selective permeabilities of gap junctions formed by different connexins or that remodeling of junctional complexes mediated through certain domains of connexins are involved in the interplay between connexins and P2Y receptors. To test these hypotheses we will up- and down-regulate expression levels of Cx43 and other gap junction proteins and measure changes in function and expression of P2Y receptor subtypes in the absence and presence of gap junction channel blockers. To evaluate whether the interplay between connexins and expression of P2Y receptors is mediated by specific domains of corinexins, we will express Cx43 lacking SH2/SH3 or PDZ sequences and test for changes in function and expression of P2Y receptor subtypes The consequences of such modification for cell-cell communication will be evaluated by measuring the properties of calcium wave spread and the strength of coupling. It is expected that by elucidating the interplay between gap junctions and P2 receptors in astrocytic intercellular communication, underlying mechanisms will be disclosed that dictate the extent to which long distance cell-to-cell signaling can propagate within the CNS.