CYCLIC NUCLEOTIDE PHOSPHODIESTERASES IN OLFACTION

这项研究计划的长期目标是确定 涉及嗅觉的基本细胞机制。一个 气味物质分子途径的关键和活性成分 转导是第二信使分子cAMP，已被证明 嗅觉刺激使嗅觉感觉神经元迅速增加。 这项提议的重点是降解这些分子的酶-- -环核苷酸磷酸二酯酶(PDE)--因此- 位于作为嗅觉信号的调制器的位置的 传到大脑。在哺乳动物中，这些酶中的一种是 果蝇Dunce基因，编码一种cAMP特异性的PDE。这个基因 最近在小鼠体内被克隆，并显示出丰富的 在嗅觉感觉神经元中优先表达。一系列 有人建议进行研究，以扩大这一初步发现。首先， Dunce同源基因的发育期称为mPDE2，将是 在嗅觉系统形成的早期建立起来的。规管 然后在退化和随后的过程中检测这种酶 单侧嗅鞘切除后嗅黏膜再生的实验研究 嗅球，它是感觉神经元轴突的靶标。 然后将使用分子遗传学中的技术来开始解决 关于这种PDE在嗅觉中作用的基本问题。首先， 将研究mPDE2的基因结构，包括调查 嗅觉组织中蛋白质和/或mRNA的异质性。然后是mPDE2 基因将被破坏或敲除，使用同源重组在 胚胎干细胞。一旦缺乏功能性mPDE2基因的小鼠 将对它们进行彻底的形态分析， 生理上和行为上的任何表型异常， 尤其是关于与以下方面相关的潜在缺陷 嗅觉功能。最后，为了更全面地解决PDE问题 在嗅觉中的作用，有必要刻画另一种 感觉神经元中发现的主要PDE--一种可激活的钙和钙调蛋白 PDE或凸轮PDE。因此，表达的CaM PDE的鉴定 提出了利用分子克隆技术建立嗅觉系统的设想。这是意料之中的 这些实验将提供关于 环核苷酸PDES在嗅觉中的作用。

The long-range goals of this research program are to define the fundamental cellular mechanisms involved in olfactory perception. A critical and active component of the molecular pathway underlying odorant transduction is the second messenger molecule cAMP, which has been shown to increase rapidly in olfactory sensory neurons upon odor stimulation. The focus of this proposal is on the enzymes that degrade these molecules- - cyclic nucleotide phosphodiesterases (PDEs)-- and are therefore well- situated to act as modulators of the olfactory signals that are ultimately transmitted to the brain. In mammals one of these enzymes is a homolog of the Drosophila dunce gene, which codes for a cAMP-specific PDE. This gene has recently been cloned in the mouse and shown to be abundantly and preferentially expressed in olfactory sensory neurons. A series of studies are proposed to extend this initial discovery. First, the developmental onset of the dunce homolog, called mPDE2, will be established during early formation of the olfactory system. Regulation of this enzyme will then be examined during degeneration and subsequent regeneration of the olfactory mucosa following unilateral removal of the olfactory bulb, which is the target of the sensory neuron axons. Techniques in molecular genetics will then be used to begin addressing basic questions concerning the role of this PDE in olfaction. First, the gene structure of mPDE2 will be studied, including investigations into the protein and/or mRNA heterogeneity in olfactory tissue. Then the mPDE2 gene will be disrupted, or knocked out, using homologous recombination in embryonic stem cells. Once the mice lacking a functional mPDE2 gene are obtained they will be thoroughly analyzed morphologically, physiologically, and behaviorally for any phenotypic abnormalities, particularly with respect to potential deficiencies associated with olfactory function. Finally, to address more completely the issue of PDE function in olfaction, it will be necessary to characterize the other major PDE found in sensory neurons-- a Ca2+ and calmodulin-activatible PDE, or CaM PDE. Therefore, identification of the CaM PDEs expressed in the olfactory system by molecular cloning is proposed. It is expected that these experiments will contribute important information about the role of cyclic nucleotide PDEs in olfaction.