Serotonin N-acethyltransferase Regulation & Inhibition

描述（由申请人提供）：该提案是一项竞争性更新申请，涉及褪黑素节律酶5 -羟色胺n -乙酰转移酶的调节、合成抑制剂的开发和催化机制。褪黑素是松果体中产生的昼夜节律激素，被认为有助于调节睡眠-觉醒周期、情绪和衰老过程。关于褪黑激素在生理和病理生理中的作用的精确细节仍然缺乏，部分原因是缺乏药理学工具。从神经递质血清素合成褪黑素涉及两个酶促步骤，第一个是由血清素n -乙酰转移酶催化。血清素乙酰转移酶的昼夜和光敏感波动驱动褪黑激素的产生，褪黑激素的水平在夜间最高。这项提议有三个主要目标。首先，我们计划开发和表征一类新型有效的血清素n -乙酰转移酶pantetheinyl前药抑制剂，有望比第一代抑制剂更有效，毒性更小。其次，我们将阐明5 -羟色胺n -乙酰转移酶磷酸化对该酶细胞稳定性的影响。已知5 -羟色胺n -乙酰转移酶在光的作用下，其n端和c端都被磷酸化，但这些磷酸化事件的完全意义尚不清楚。通过将非水解的磷酸氨基酸类似物代替磷苏氨酸和磷丝氨酸加入血清素n-乙酰转移酶中，可以揭示磷酸化的确切作用。第三，我们将阐明14-3-3蛋白募集对血清素n -乙酰转移酶催化性能的影响。由于5 -羟色胺乙酰转移酶的主要体内形式可能与14-3-3络合，这些研究将允许表征该酶的生理相关形式。预计这些研究将增加我们对褪黑激素在健康和疾病中的作用的理解，新设计的抑制剂可能作为治疗睡眠和情绪障碍的主要药物。

DESCRIPTION (provided by applicant): This proposal is a competing renewal application that concerns the regulation, development of synthetic inhibitors, and catalytic mechanism of serotonin N-acetyltransferase, the melatonin rhythm enzyme. Melatonin is circadian rhythm hormone produced in the pineal gland that is hypothesized to contribute to the regulation of sleep-wake cycle, mood, and the process of aging. Precise details about the role of melatonin in physiology and pathophysiology are still lacking, in part because of a dearth of pharmacologic tools. The biosynthesis of melatonin from the neurotransmitter serotonin involves two enzymatic steps, the first of which is catalyzed by serotonin N-acetyltransferase. The diurnal and light-sensitive fluctuation in serotonin Nacetyltransferase drives the rise and fall of melatonin production, the level of which is highest at night. This proposal has three principal goals. First, we plan to develop and characterize a novel class of potent pantetheinyl-prodrug inhibitors of serotonin N-acetyltransferase that promise to be more potent and less toxic than first generation inhibitors. Second, we will elucidate the impact of phosphorylation of serotonin N-acetyltransferase on the cellular stability of the enzyme. Serotonin N-acetyltransferase is known to be phosphorylated on both its N-and C-termini in response to light, but the complete significance of each of these phosphorylation events is not yet known. By incorporating non-hydrolyzable phosphono amino acid analogs in place of phosphothreonine and phosphoserine into serotonin N-acetyltransferase, the precise role of phosphorylation should be revealed. Third, we will clarify the effects of 14-3-3 protein recruitment on the catalytic properties of serotonin N-acetyltransferase. Since the predominant in vivo form of serotonin Nacetyltransferase is probably complexed with 14-3-3, these studies will permit characterization of the physiologically relevant form of this enzyme. It is expected that these studies will lead to an increase in our understanding about the role of melatonin in health and disease and that newly designed inhibitors may serve as lead agents for the treatment of sleep and mood disorders.