CFTR regulation of thyroid transport

描述(由申请人提供)：甲状腺激素在生物体的整个生命过程中发挥着不同和重要的生理作用，从多器官系统的发育到代谢率的调节。甲状腺是一种独特的上皮集合体。 有组织地分泌分泌激素的支架的卵泡，甲状腺球蛋白也是如此 AS将生成的甲状腺激素前体进行碘化和储存。它们还通过处理和释放甲状腺激素来回应对甲状腺激素的信号需求。与适当的激素合成相关的过程发生在卵泡内，在许多疾病状态下也会受到影响。我们的长期目标是了解甲状腺滤泡腔成分是如何维持的。我们的研究小组最近证实了甲状腺中存在囊性纤维化跨膜电导调节因子(CFTR)，它可以通过cAMP刺激的顶端定位的负离子出口传导途径来调节甲状腺阴离子的分泌。考虑到甲状腺激素在许多重要的生理过程中的重要性，识别和了解CFTR在甲状腺功能中的作用是至关重要的。本提案旨在理解并建立一个模型来描述CFTR和SLC5A8之间的调控相互作用。SLC5A8是一种在甲状腺滤泡上皮细胞顶膜上高度表达的溶质转运体。我们的研究表明，SLC5A8的活性依赖于CFTR的激活，因此提示了功能相互作用。在已报道的SLC5A8功能中，包括在碘转运、短链脂肪酸转运和肿瘤抑制中的作用。所有这些都与甲状腺健康和疾病有潜在的高度相关性，但令人惊讶的是，人们对它们知之甚少。CFTR对不同基因家族(SLC26)的其他溶质运输分子的调控已经得到了很好的研究。目前对SLC26的CFTR调控模型表明，支架分子促进了蛋白质-蛋白质的相互作用。SLC5A8包含一个研究得很好的蛋白质相互作用基序，该基序也在CFTR中发现，但文献中没有关于其功能作用的信息。我们假设CFTR通过蛋白质-蛋白质相互作用调节SLC5A8。在两栖动物和哺乳动物细胞模型系统中使用异源共表达CFTR和SLC5A8的初步数据与假设的预测一致。建议的研究策略结合了成熟的方法来定义大分子复合体(ES)内CFTR和SLC5A8相互作用(S)的分子要求，以及它们的调节串扰，即相互作用的功能结果。我们建议的研究利用互补的生化/细胞生物学方法以及功能电生理和荧光测量。由此产生的信息将被集成到模型中，这些模型可以反复挑战、开发和改进。本提案将首次检验CFTR和SLC5A8都与一个共同的大分子复合体相关的假设。不仅所有的新发现都将是新的和新奇的，而且它们可能会影响多个领域的方向。

DESCRIPTION (provided by applicant): Thyroid hormones function in diverse and important physiological roles throughout the life an organism, ranging from the development of multiple organ systems to the regulation of metabolic rate. The thyroid is a unique collection of epithelial follicles that are organized to secrete the scaffold for hormone production, thyroglobulin, as well as iodinate and store the resultant thyroid hormone precursor. They also respond to the signaled need for thyroid hormone by processing and releasing thyroid hormones. Processes relevant to proper hormone synthesis take place within the follicle and also are compromised in many disease states. Our long-term goal is to understand how the thyroid follicular lumen composition is maintained. Our group recently positively established the presence of Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) in thyroid, where it can mediate thyroid anion secretion via an apically localized, cAMP-stimulated, conductive pathway for anion exit. Considering the importance of thyroid hormone to so many essential physiological processes, it is critical to identify and understand the role of CFTR in thyroid function. The present proposal aims to understand and develop a model describing the regulatory interaction between CFTR and SLC5A8, a solute transporter that is highly expressed at the apical membrane of the thyroid follicular epithelial cell. Our studies indicate that SLC5A8 activity depends on activation of CFTR, thus suggesting functional interactions. Among the reported functions for SLC5A8 are roles in iodide transport, short-chain fatty acid transport and tumor suppression. All are of potentially high relevance to thyroid health and disease and yet surprisingly little is known about them. CFTR regulation of other solute transport molecules of a different gene family (SLC26) is well-studied. Current models for CFTR regulation of SLC26s indicate protein-protein interactions that are facilitated by scaffolding molecules. SLC5A8 contains a well-studied protein interaction motif that is also found in CFTR, yet no information about its functional role exists in the literature. We hypothesize that CFTR regulates SLC5A8 via protein-protein interactions. Preliminary data using heterologous co-expression of CFTR and SLC5A8 in amphibian and mammalian cell model systems align with the predictions of the hypothesis. The proposed research strategy combines well-established methods to define both the molecular requirements for CFTR and SLC5A8 interaction(s) within macromolecular complex (es), as well as their regulatory crosstalk, i.e. the functional outcomes of interaction. Our proposed studies utilize complementary biochemical/cell biological approaches and functional electrophysiological and fluorimetric measurements. The resulting information will be integrated into models that can be iteratively challenged, developed and refined. The present proposal will be the first to test the hypothesis that both CFTR and SLC5A8 associate within a common macromolecular complex. Not only will all emergent findings be new and novel, but they potentially will impact the direction of multiple fields.