METABOLISM AND FUNCTION OF CYCLIC NUCLEOTIDE

本申请人的一个普遍的、长期的兴趣是理解环核苷酸磷酸二酯酶（PDE）在确定细胞中第二信使环核苷酸信号的幅度和持续时间中所起的作用。 很明显，为了做到这一点，人们需要知道哺乳动物组织中存在多少不同的PDE，它们是如何表达的，在哪里表达，以及它们是如何调节的。 一旦鉴定和表征，则通常可以确定不同PDE同工酶的功能。 这份赠款申请概述了这一过程的两个阶段。 首先，我们建议继续寻找新的偏微分方程及其动力学和调节特性的后续表征。 与前几年相比，一个主要的区别是，我们现在正在使用更现代的生物信息学方法来处理这一过程的初始方面。 本申请的第二部分提出了用于定义一种特异性磷酸二酯酶PDE 3B作为几种不同细胞类型中生长因子和细胞因子功能的调节剂的一些功能的具体实例。 具体的例子包括通过瘦素刺激PDE3B调节肝脏中的葡萄糖代谢、肾上腺中的皮质醇合成和下丘脑中的进食行为的测试。 也将进行使用其他细胞因子的类似方法。 这些研究有可能定义细胞因子的全新分子作用机制和PDE 3B的全新一般生理作用。

A general, long standing interest of the applicant has been to understand the role(s) played by cyclic nucleotide phosphodiesterases (PDEs) in determining the amplitude and duration of second messenger cyclic nucleotide signals in the cell. It has always been clear that in order to do this one needs to know how many different PDEs are present in mammalian tissues, how and where they are expressed, and how they are regulated. Once identified and characterized it is then often possible to determine what functions are subserved by distinct PDE isozymes. This grant application outlines two phases of this process. First, we propose a continuation of our search for new PDEs and subsequent characterization of their kinetic and regulatory properties. One major difference compared to previous years is that we are now using more modern bioinformatic approaches for the initial aspects of this process. The second part of the application proposes specific examples for defining some the functions of one specific phosphodiesterase, PDE3B, as a modulator of growth factor and cytokine function in several different cell types. Specific examples include tests for the regulation by leptin stimulation of PDE3B of glucose metabolism in the liver, of cortisol synthesis in the adrenal and of feeding behavior in the hypothalamus. Similar approaches with other cytokines will also be carried out. These studies have the potential to define a whole new molecular mechanism of action for cytokines and a whole new general physiological role for PDE3B.