Regulation of kainate receptor expression in cone bipolar cells

这项工作的长期目标是了解视网膜的分子遗传基础， 传输和处理灯关闭时产生的信号。锥状光感受器 在白天调节视力，并使用谷氨酸作为它们的发射器。锥状信号被传送到 通过两种功能类别的双极细胞，开和关，它们具有不同的 谷氨酸受体，使他们去电（即信号），无论是在光或光关闭，分别。 双极细胞的每一功能类别又可细分为5-6个解剖类型。本研究 重点关注主要表达保持符号的红藻氨酸型谷氨酸的关闭双极细胞 受体（亚单位GluK 1 -5）。令人惊讶的是，虽然AMPA受体在大多数CNS中占主导地位， 突触，红藻氨酸受体在大多数Off双极细胞的锥体突触中占主导地位 类型至少有四个原因值得研究。第一，时间信令属性 红藻氨酸受体与AMPA受体的不同，这些差异可能 改变穿过视网膜的关闭信号的大小和定时， 的方式其次，在大多数研究充分的突触中，红藻氨酸受体几乎总是含有 GluK 2亚基，而关闭双极细胞选择研究较少的GluK 1亚基作为其 主子单元代替。第三，关闭双极细胞表达Neto 1，一种辅助受体亚基， 深刻地改变了含GluK 2受体的体内反应。Neto 1对 内源性含GluK 1受体尚未研究。第四，功能性 已经描述了Off双极细胞上不同红藻氨酸受体的性质， 他们的不同反应的基础还没有建立。要确定子单元基础， 信号在关闭双极细胞突触，我们建议研究小鼠的突触反应，其中 受体亚单位（GluK 1-GluK 5）被永久或急性地单独敲除。 将进行类似的研究，以确定辅助亚基Neto 1在通信中的作用。 三个具体的目标将1）确定介导关闭双极突触反应的亚基 细胞类型1a、2和3a; 2）确定Neto蛋白在关闭双极信号传导中的功能 细胞突触; 3）确定GluK 1 -1d亚基的生理功能，这是独特的 在视网膜上，是将GluK 1 -1d亚基定位于突触的分子因子。

The long term objective of this work is to understand the molecular genetic basis for how the retina transmits and processes the signals produced when lights are turned off. Cone photoreceptors mediate vision during daylight and use glutamate as their transmitter. The cone signals are carried across the retina by two functional classes of bipolar cells, On and Off, which have different glutamate receptors that cause them to depolarize (ie, signal) either at light-on or -off, respectively. Each functional class of bipolar cell can be subdivided into 5-6 anatomical types. This study focuses on the Off bipolar cells that chiefly express sign-preserving kainate-type glutamate receptors (subunits GluK1-5). Surprisingly, while AMPA receptors predominate at most CNS synapses, kainate receptors predominate at the cone synapses of most of the Off bipolar cell types. They are important to study for at least four reasons. First, the temporal signaling properties of kainate receptors differ from those of AMPA receptors, and these differences are likely to change the size and timing of the Off signals traversing the retina in as yet poorly understood ways. Second, the kainate receptors at most well-studied synapses almost always contain the GluK2 subunit, whereas the Off bipolar cells choose the less well-studied GluK1 subunit as their main subunit instead. Third, Off bipolar cells express Neto1, an auxiliary receptor subunit that profoundly alters the in vivo responses of GluK2-containing receptors. The effect of Neto1 on endogenous GluK1-containing receptors has not yet been studied. And fourth, while the functional properties of different kainate receptors on the Off bipolar cell have been described, the molecular basis for their diverse responses has not been established. To determine the subunit basis for signaling at the Off bipolar cell synapse, we propose to study synaptic responses in mice in which receptor subunits (GluK1-GluK5) are individually knocked out either permanently or acutely. Similar studies will be performed to define the role of the auxiliary subunit Neto1 in communication. Three specific aims will 1) determine the subunits that mediate synaptic responses in Off bipolar cell types 1a, 2, and 3a; 2) determine the function of Neto proteins in signaling at the Off bipolar cell synapse; and, 3) determine the physiological function of the GluK1-1d subunit, which is unique to the retina, the molecular factors that localize the GluK1-1d subunit to the synapse.