Salivary gland hypofunction & genetic defects

唾液腺功能减退

• 批准号: 6713313
• 负责人: JAMES E MELVIN
• 金额: $ 18.89万
• 依托单位: UNIVERSITY OF ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-04-01 至 2005-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6713313
• 关键词: Xenopus oocyte; chloride channels; genetic disorder; genetically modified animals; human tissue; laboratory mouse; membrane channels; membrane structure; membrane transport proteins; molecular cloning; potassium channel; protein structure function; saliva; salivary glands; secretion; xerostomias

Approximately 20% of xerostomia cases are of unknown etiology. Many of these idiopathic "dry mouth" disorders are likely due to genetic defects in the fluid transport mechanism. An initial step in the development of treatments for these latter individuals is to identify the key transport proteins involved in the fluid secretion process. Secretion is driven by the activation of K+ and C1-channels. Several distinct types of K+ and Cl- channels have been functionally identified in salivary acinar cells, but only a few of these have been identified as specific gene products. Some of the properties of these proteins have been determined but little is known about the specific contribution these channels make to the fluid secretion process. Thus, the long-term objective of this Subproject is to identify the K+ and Cl-channel proteins essential for saliva production in human and mouse parotid glands. We will attempt to corroborate our findings in humans identified as suffering from idiopathic dry mouth as part of Subproject 3. Aim 1 will distinguish which of the different K+ and Cl-channels are functionally important to the production of saliva by characterizing channel different K+ and Cl-channels are functionally important in the production of saliva by characterizing channel biophysics. We will coordinate our efforts with Subproject 1 in order to determine the physiologically relevant effects of agonist-induced signals on the activation of K+ and Cl-channels. In Aim 2, the molecular identity of the channels expressed in human and mouse parotid acinar cells will be determined by cloning cDNAs that encode the corresponding K+ and Cl- channel proteins. The results from Aims 1 and 2, as well as those from Subproject 1, will provide essential information for predicting the role of individual channels in the secretion process. However, owing to the lack of different pharmacology for many channels in the test of the importance of a given protein can be obtained most easily by studying an animal defective in the expression of the channel. In Aim 3 the functional significance of specific channel proteins will be determined by examining the effects of gene disruption. Mice lacking expression of two different Cl-channels are currently available for study (CFTR and C1C3). Additional channels found to play critical roles in secretion that can not be selectively blocked with inhibitors will be eliminated in mice by targeted recombination. The results of these studies are expected to uncover the genetic basis for some forms of idiopathic salivary gland hypofunction and to provide a foundation for the development of treatments for these individuals as well as those patients suffering from other forms of salivary gland dysfunction.

大约 20% 的口干症病例病因不明。许多特发性“口干”疾病可能是由于液体运输机制的遗传缺陷造成的。开发针对这些个体的治疗方法的第一步是确定参与液体分泌过程的关键转运蛋白。分泌是由 K+ 和 C1 通道的激活驱动的。在唾液腺泡细胞中已在功能上鉴定出几种不同类型的 K+ 和 Cl- 通道，但其中只有少数被鉴定为特定的基因产物。这些蛋白质的一些特性已被确定，但人们对这些通道对液体分泌过程的具体贡献知之甚少。因此，该子项目的长期目标是鉴定人类和小鼠腮腺唾液产生所必需的 K+ 和 Cl-通道蛋白。作为子项目 3 的一部分，我们将尝试在被确定患有特发性口干的人类中证实我们的发现。目标 1 将通过表征不同的 K+ 和 Cl 通道来区分不同的 K+ 和 Cl-通道中哪一个对于唾液的产生具有重要功能-通过表征通道生物物理学，通道在唾液产生中具有重要的功能。我们将与子项目 1 协调工作，以确定激动剂诱导信号对 K+ 和 Cl-通道激活的生理相关影响。在目标 2 中，将通过克隆编码相应 K+ 和 Cl- 通道蛋白的 cDNA 来确定人和小鼠腮腺腺泡细胞中表达的通道的分子身份。目标 1 和 2 以及子项目 1 的结果将为预测各个通道在分泌过程中的作用提供重要信息。然而，由于许多通道缺乏不同的药理学，在测试中可以通过研究通道表达缺陷的动物来最容易地获得给定蛋白质的重要​​性。在目标 3 中，将通过检查基因破坏的影响来确定特定通道蛋白的功能意义。目前可用于研究缺乏两种不同 Cl 通道表达的小鼠（CFTR 和 C1C3）。发现在分泌中发挥关键作用且不能用抑制剂选择性阻断的其他通道将通过靶向重组在小鼠中被消除。这些研究的结果预计将揭示某些形式的特发性唾液腺功能减退症的遗传基础，并为开发针对这些个体以及患有其他形式的唾液腺功能障碍的患者的治疗方法奠定基础。