Transduction Mechanism in Olfactory Receptor Neurons

嗅觉受体神经元的转导机制

• 批准号: 8472471
• 负责人: KING-WAI YAU
• 金额: $ 31.73万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-08-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8472471
• 关键词: Action Potentials; Adenylate Cyclase; Affect; Amphibia; Arrestins; Attention; Binding; Brain; Cilia; Complex; Cyclic Nucleotides; Detection; Disabled Persons; Disease; Dissociation; Event; Feedback; G Protein-Coupled Receptor Signaling; Genetic; Genetically Engineered Mouse; Golf; Grant; Health; Human; Individual; Insecta; Membrane; Mus; Nose; Odorant Receptors; Olfactory Receptor Neurons; Pathway interactions; Phosphorylation; Phototransduction; Physiological; Probability; Rana; Relative (related person); Reporting; Retinal Cone; Retinal Pigments; Shapes; Signal Transduction; Smell Perception; Solutions; Stimulus; Suction; System; Time; genetic manipulation; insight; receptor; research study; response; retinal rods; Action Potentials; Adenylate Cyclase; Affect; Amphibia; Arrestins; Attention; Binding; Brain; Cilia; Complex; Cyclic Nucleotides; Detection; Disabled Persons; Disease; Dissociation; Event; Feedback; G Protein-Coupled Receptor Signaling; Genetic; Genetically Engineered Mouse; Golf; Grant; Health; Human; Individual; Insecta; Membrane; Mus; Nose; Odorant Receptors; Olfactory Receptor Neurons; Pathway interactions; Phosphorylation; Phototransduction; Physiological; Probability; Rana; Relative (related person); Reporting; Retinal Cone; Retinal Pigments; Shapes; Signal Transduction; Smell Perception; Solutions; Stimulus; Suction; System; Time; genetic manipulation; insight; receptor; research study; response; retinal rods

PROJECT SUMMARY The long-term objective of this proposal is to understand in quantitative detail the transduction mechanism in vertebrate olfactory receptor neurons (ORNs). During the current grant period, we have been able to resolve the response triggered by a single odorant-binding event on an ORN (the so- called "unitary response"). Surprisingly, we found that randomly encountered ORNs (and therefore randomly encountered odorant receptors, or ORs) all gave unitary responses of similar amplitudes, suggesting that an odorant-binding event has a very low probability of signaling downstream. In other words, the unitary response appears to reflect the effect of a single activated Golf/adenylyl cyclase complex. This phenomenon is apparently due to a very short odorant dwell-time on the OR molecule (i.e., rapid dissociation of the odorant from the OR). This short odorant dwell-time likewise dominates the termination of olfactory transduction. Hence, the traditionally believed determinants for terminating G-protein-coupled receptor (GPCR) signaling, namely, receptor phosphorylation and subsequent arrestin binding, are unimportant at least at the level of the unitary response, although they may still be important with intense and prolonged odorant stimulation. So far, the above results have been obtained from amphibian ORNs and in low-Ca2+ solution (in order to boost the unitary-response amplitude). In this application, we propose to continue experiments with amphibian ORNs but at the same time to use also mouse ORNs, which offer the distinct advantage of genetic manipulations. Aim 1 is to obtain the best estimate of the olfactory unitary-response amplitude in frog ORNs in physiological conditions (i.e., normal external Ca2+), to characterize its spatial spread along the olfactory cilium, to dissect its membrane-current components (cyclic-nucleotide-gated current versus Cl current), and to estimate the number of unitary responses required for bringing the ORN to firing threshold. Aim 2 is to launch a similar detailed study of the unitary response in mouse ORNs, which will serve as the groundwork for examining available genetic mouse lines for olfactory transduction. Aim 3 is to study/dissect Ca-dependent and Ca-independent adaptation by ORNs in more detail, largely by making use of genetic mouse lines. Aim 4 is to study constitutive OR activity in the absence of odorants, which so far has received little attention in vertebrate olfactory transduction. We have noticed this phenomenon in the course of previous experimentation. The experimental approach will involve predominantly suction-pipette recording from single ORNs of frog and WT or genetically engineered mice.

项目摘要 该提议的长期目标是量化转导的详细信息 脊椎动物嗅觉受体神经元（ORNS）的机制。在当前赠款期间，我们有 能够解决由ORN上的单个气味结合事件触发的响应（So- 称为“统一响应”）。令人惊讶的是，我们发现随机遇到的ORN（因此 随机遇到的气味受体或ORS）都给出了类似振幅的单一反应， 表明气味结合事件的下游信号传导的可能性很低。在其他 单词，单一响应似乎反映了单个激活的高尔夫/腺苷酸环化酶的效果 复杂的。这种现象显然是由于在或分子上的非常短的气味停留时间 （即，气味与OR的快速解离）。这个短气味的住所同样占主导地位 嗅觉转导的终止。因此，传统上认为终止的决定因素 G蛋白偶联受体（GPCR）信号传导，即受体磷酸化和随后的。 抑制蛋白结合，至少在单一响应水平上并不重要，尽管它们可能仍然是 重要的是强烈和长时间的气味刺激。到目前为止，上述结果已经 从两栖ORN和低CA2+溶液中获得（为了增强单一响应 振幅）。在此应用中，我们建议继续使用两栖动物进行实验，但在 同时还使用鼠标ORN，这为遗传操作提供了明显的优势。 目的1是获得对青蛙Orn中嗅觉统一响应幅度的最佳估计。 生理状况（即正常的外部Ca2+），以表征其空间沿 嗅觉纤毛，以剖析其膜电流成分（环核苷酸门控电流与CL 当前），并估计将ORN射击所需的单一响应数量 临界点。 AIM 2是对鼠标ORN中的单一响应进行类似的详细研究，该研究 将作为检查可用的遗传小鼠线以进行嗅觉转导的基础。 目标3是在更详细地研究/剖析ORN的CA依赖性和与CA无关的适应 通过使用遗传小鼠线。目标4是在没有的情况下研究构成或活动 到目前为止，这种气味很少关注脊椎动物嗅觉转导。我们注意到了 在先前的实验过程中，这种现象。 实验方法将主要涉及单个单一的吸入卷板记录 青蛙和WT或基因工程小鼠的ORNS。