XLas Relative to Gsa in Bone and Mineral Ion Metabolism

XLas 在骨和矿物质离子代谢中相对于 Gsa

• 批准号: 8852595
• 负责人: MURAT BASTEPE
• 金额: $ 37.46万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-08-01 至 2016-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8852595
• 关键词: 25-hydroxyvitamin D; Ablation; Address; Adult; Affect; Animals; Biological Process; Calvaria; Cell Line; Cell membrane; Cells; Clinical; Cyclic AMP; Data; Development; Dihydroxycholecalciferols; Disease; Dynamin; Embryo; Employee Strikes; Exons; GTP-Binding Proteins; Generations; Genes; Goals; Health; Hormones; Human; Hypocalcemia result; Injection of therapeutic agent; Ions; Kidney; Knockout Mice; Knowledge; Lead; Learning; Life; Measures; Mediating; Messenger RNA; Metabolism; Minerals; Mixed Function Oxygenases; Mus; Mutant Strains Mice; Mutation; Parathyroid Hormone Receptor; Parathyroid gland; Pathogenesis; Patients; Phenotype; Phosphorylation; Physiology; Play; Proteins; Proximal Kidney Tubules; Pseudohypoparathyroidism; Receptor Signaling; Regulation; Relative (related person); Resistance; Role; Serum; Signal Pathway; Signal Transduction; Skeletal Development; Skeletal system; System; Testing; Tissues; Transgenic Mice; Tubular formation; Variant; analog; bone; calcium metabolism; design; human disease; improved; in vivo; inorganic phosphate; insight; kidney cell; mouse model; mutant; novel; overexpression; parathyroid hormone-related protein; phosphorus metabolism; postnatal; promoter; pup; receptor internalization; reconstitution; response; reuptake; skeletal tissue; tandem mass spectrometry

DESCRIPTION (provided by applicant): Gαs is critical for the actions of PTH and PTHrP. The gene encoding Gαs (GNAS) also gives rise to XLαs, which is expressed in various tissues including osteoblastic and renal cells. XLαs can mimic Gαs by stimulating cAMP generation in response PTH, although it is also predicted to have unique actions. Mutations in GNAS are found in several human diseases that impair signaling through the PTH/PTHrP receptor (PTHR). Most of these mutations affect both Gαs and XLαs. Studies in mice and humans indicate that XLαs plays important roles in physiology and human disease, but the actions of XLαs remain poorly understood. Our recent studies have provided novel insights into the cellular actions of XLαs, and together with our findings obtained from XLαs knockout (XLKO) mice, these led us to hypothesize that XLαs is necessary for the regulation of calcium and phosphorus metabolism in vivo. In Aim 1 of the current proposal, we will address whether XLαs is necessary for PTH-mediated actions in the renal proximal tubule during early postnatal development. We will determine a) whether proximal tubular actions of PTH in XLKO mice are impaired and b) whether the PTH resistance phenotype in XLKO mice is rescued by transgenically reconstituting XLαs expression in the proximal tubule. In Aim 2, we will address whether XLαs allows PTH actions to be sustained in the renal proximal tubule, which could explain the PTH resistance phenotype in XLKO mice. We will thus determine a) whether PTHR internalization is enhanced in the proximal tubule of XLKO mice; b) whether the PTH resistance phenotype in XLKO mice can be rescued by a mutant PTHR with sustained activity or by overexpressing Gαs in the proximal tubule; and c) whether the interaction of XLαs with dynamin influences PTH actions. These studies will provide novel insights into the actions of PTH and XLαs in the renal proximal tubule, and these will be applicable to the actions of these proteins in skeletal tissues. Our results will also help reveal the roles of XLαs in other systems, in addition to improving our knowledge of the mechanisms underlying the diseases caused by GNAS mutations. Given that XLαs can activate the ubiquitous cAMP signaling pathway, our results will likely have even broader implications for human health and disease.

性状（由申请方提供）：Gαs对PTH和PTHrP的作用至关重要。编码Gαs（GNAS）的基因也产生XLαs，XLαs在各种组织中表达，包括成骨细胞和肾细胞。XLαs可以通过刺激cAMP生成来响应PTH而模拟Gαs，尽管它也被预测具有独特的作用。在几种人类疾病中发现了GNAS突变，这些疾病损害了通过PTH/PTHrP受体（PTHR）的信号传导。这些突变中的大多数影响Gαs和XLαs。对小鼠和人类的研究表明，XLαs在生理学和人类疾病中起着重要作用，但XLαs的作用仍然知之甚少。我们最近的研究为XLαs的细胞作用提供了新的见解，结合我们从XLαs敲除（XLKO）小鼠中获得的发现，这些使我们假设XLαs对体内钙和磷代谢的调节是必需的。在当前提案的目标1中，我们将讨论XLαs是否是出生后早期发育期间肾近端小管中PTH介导的作用所必需的。我们将确定a）XLKO小鼠中PTH的近端肾小管作用是否受损，以及B）XLKO小鼠中的PTH抗性表型是否通过转基因重建近端肾小管中的XLαs表达来挽救。在目标2中，我们将讨论XLαs是否允许PTH作用在肾近端小管中持续，这可以解释XLKO小鼠中的PTH抗性表型。因此，我们将确定a）XLKO小鼠近端小管中PTHR内化是否增强; B）XLKO小鼠中PTH抗性表型是否可以通过具有持续活性的突变PTHR或通过近端小管中Gαs的过表达来挽救;以及c）XLαs与发动蛋白的相互作用是否影响PTH作用。这些研究将为PTH和XLαs在肾近端小管中的作用提供新的见解，这些研究将适用于这些蛋白质在骨骼组织中的作用。我们的研究结果也将有助于揭示XLαs在其他系统中的作用， 提高我们对GNAS突变引起的疾病的潜在机制的认识。鉴于XLαs可以激活普遍存在的cAMP信号通路，我们的研究结果可能对人类健康和疾病产生更广泛的影响。