Role of XLalphas as a novel alpha-subunit of Gs in hormone signaling

XLalphas 作为 Gs 的新型 α 亚基在激素信号传导中的作用

基本信息

批准号：
7475183
负责人：
MURAT BASTEPE
金额：
$ 31.73万
依托单位：
MASSACHUSETTS GENERAL HOSPITAL
依托单位国家：
美国
项目类别：
财政年份：
2007
资助国家：
美国
起止时间：
2007-08-01 至 2011-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7475183
关键词：
Ablation Address Adenoviruses Adenylate Cyclase Adult Alleles Amino Acid Motifs Animal Model Biochemical Biological Biological Process Cell Line Cells Complex Cyclic AMP Defect Development Diagnostic Disease Energy Metabolism Exons G-Protein-Coupled Receptors GNAS gene GTP-Binding Proteins Generations Genes Genomic Imprinting Glucose Goals Hormones Hypocalcemia result In Vitro Inherited Investigation Kidney Knock-out Lead Mediating Mediator of activation protein Modeling Mouse Strains Mus Mutation N-terminal Parathyroid Hormones Pathogenesis Patients Pharmaceutical Preparations Phenotype Physiology Protein Overexpression Proteins Proximal Kidney Tubules Pseudohypoparathyroidism Regulation Research Personnel Resistance Role Signal Pathway Signal Transduction Signaling Protein Technology Testing Tissues Transgenic Organisms Tubular formation adipocyte biology animal data base feeding genetic manipulation glucose metabolism hormone resistance human PTH protein human disease improved in vivo mouse model novel postnatal promoter receptor receptor coupling response tool

项目摘要

DESCRIPTION (provided by applicant): XLocs and Gsa, the alpha subunit of the stimulatory G protein (Gsa), are two related proteins derived from the same gene locus, GNAS. XLas differs from the alpha subunit of the stimulatory G protein (Gsa) by a large N-terminal domain with unique sequence. It is otherwise identical to the latter and comprises most of the domains shown to be functionally important for Gsa. Thus, XLas is predicted to act as a novel alpha subunit of the stimulatory G protein. However, owing to its unique N-terminal domain, XLas could importantly differ from Gsa with respect to its biological roles and regulation. When introduced into cells endogenously lacking Gsa and XLas (Gnas^"'" cells), XLas can mediate receptor-stimulated cAMP generation, but receptor coupling to XLas could not be demonstrated in several other cell lines and tissues, suggesting that the actions of XLas can be cell-specific. The animal models in which XLas is ablated have established that XLas is essential for many biological processes, including postnatal adaptation to feeding, energy and glucose metabolism, and adipocyte biology. However, these in vivo studies were unable to demonstrate a role for XLas as a signaling protein that is similar to Gsa. Thus, the biological roles of XLas currently remain unclear. Our main objective is to determine the role of XLas as a novel alpha subunit that can replace Gsa in vivo. In Specific Aim 1, we propose to address whether XLas can substitute for Gsa in vivo by studying the actions of parathyroid hormone in the renal proximal tubule as an in vivo setting whereby the roles of XLos and Gsa can be studied precisely. In Specific Aim 2, we propose to determine whether XLas is involved in the temporal development of PTH-resistance as seen in patients with pseudohypoparathyroidism, a disorder caused by mutations disrupting Gsa activity and/or expression. For accomplishing our aims, we will investigate proximal tubular PTH responsiveness in various transgenic and knockout mouse strains generated by us or by our collaborators. These studies will reveal the interacting roles of XLas and Gsa in the proximal tubular PTH actions and are predicted to improve the understanding of hormone responses that typically involve G protein-coupled receptors. Ultimately, given the importance of this signaling pathway in normal physiology and human disease, our investigations may lead to the identification of novel targets for development of new drugs and diagnostic tools.

描述（由申请人提供）：XLocs 和 Gsa（刺激性 G 蛋白（Gsa）的 α 亚基）是源自同一基因座 GNAS 的两种相关蛋白。 XLas 与刺激性 G 蛋白 (Gsa) 的 α 亚基的不同之处在于具有独特序列的大型 N 末端结构域。它在其他方面与后者相同，并且包含大多数对 Gsa 具有重要功能的结构域。因此，XLas 预计将充当刺激性 G 蛋白的新型 α 亚基。然而，由于其独特的 N 端结构域，XLas 在其生物学作用和调节方面可能与 Gsa 存在重大差异。当引入内源性缺乏 Gsa 和 XLas 的细胞（Gnas^"'" 细胞）时，XLas 可以介导受体刺激的 cAMP 生成，但在其他几种细胞系和组织中无法证明受体与 XLas 的偶联，这表明 XLas 的作用可以是细胞特异性的。 XLas 被消融的动物模型已证实 XLas 对于许多生物过程至关重要，包括出生后对进食的适应、能量和葡萄糖代谢以及脂肪细胞生物学。然而，这些体内研究无法证明 XLas 作为类似于 Gsa 的信号蛋白的作用。因此，XLas 的生物学作用目前仍不清楚。我们的主要目标是确定 XLas 作为一种可以在体内替代 Gsa 的新型 α 亚基的作用。在具体目标 1 中，我们建议通过研究甲状旁腺激素在肾近曲小管中的作用作为体内环境，从而可以精确研究 XLos 和 Gsa 的作用，从而解决 XLos 是否可以在体内替代 Gsa。在具体目标 2 中，我们建议确定 XLas 是否参与 PTH 抗性的时间发展，如假性甲状旁腺功能减退症患者中所见，这是一种由破坏 Gsa 活性和/或表达的突变引起的疾病。为了实现我们的目标，我们将研究我们或我们的合作者产生的各种转基因和敲除小鼠品系的近端肾小管 PTH 反应性。这些研究将揭示 XLas 和 Gsa 在近端肾小管 PTH 作用中的相互作用，并预计将提高对通常涉及 G 蛋白偶联受体的激素反应的理解。最终，考虑到该信号通路在正常生理学和人类疾病中的重要性，我们的研究可能会导致确定新靶点，以开发新药物和诊断工具。