Regulation of kainate receptor expression in cone bipolar cells

这项工作的长期目标是了解视网膜如何 传输和处理关灯时产生的信号。视锥感光器 白天调节视力，并使用谷氨酸作为其递质。圆锥信号被携带 穿过视网膜的两种双极细胞，开和关，它们有不同的 谷氨酸受体使它们分别在亮起或熄灭时去极化(即信号)。 双极细胞的每一种功能类型可细分为5-6个解剖类型。本研究 重点关注主要表达保留符号的海人酸型谷氨酸的非双极细胞 受体(GluK1-5亚基)。令人惊讶的是，虽然AMPA受体在大多数中枢神经系统中占主导地位 突触，海人藻酸受体在大多数非双极细胞的锥体突触中占主导地位 类型。学习它们很重要，至少有四个原因。首先，时间信令属性 红藻氨酸受体与AMPA受体的不同，这些差异可能会 改变穿过视网膜的关闭信号的大小和时间尚不清楚 方式。其次，在研究最充分的突触中，海人藻酸受体几乎总是包含 GluK2亚基，而非双极细胞选择研究较少的GluK1亚基作为其 取而代之的是主亚单位。第三，Off双极细胞表达Neto1，这是一种辅助受体亚单位， 深刻改变含GluK2受体的体内反应。Neto1对大鼠血管内皮细胞生长的影响 内源性GluK1受体尚未被研究。第四，虽然功能性的 已描述了非双极细胞上不同的海人藻酸受体的特性，分子 他们作出不同反应的基础尚未确立。要确定的子单位基准，请执行以下操作 在非双极细胞突触的信号，我们建议研究小鼠的突触反应 受体亚基(GluK1-GluK5)分别被永久或急性地敲除。 将进行类似的研究，以确定辅助亚单位Neto1在通信中的作用。 三个特定的目标将1)确定介导非双相突触反应的亚单位 细胞类型1a、2和3a；2)Neto蛋白在离开双极时的信号传递功能 细胞突触；以及，3)确定GluK1-1D亚基的生理功能，这是唯一的 对于视网膜，将GluK1-1D亚单位定位到突触的分子因素。

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.