Calcium sensing receptor and scaffolds

钙敏感受体和支架

• 批准号: 7081943
• 负责人: GERDA E BREITWIESER
• 金额: $ 29.6万
• 依托单位: GEISINGER CLINIC
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-04-01 至 2010-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7081943
• 关键词: actin binding protein; allosteric site; arrestins; biological signal transduction; calcium flux; calcium indicator; cell surface receptors; confocal scanning microscopy; gene mutation; mitogen activated protein kinase; protein protein interaction; protein structure function; receptor binding; receptor expression

DESCRIPTION (provided by applicant): The calcium sensing receptor (CaR) transduces local changes in extracellular calcium and metabolites (anrtino acids, polyamines) into intracellular signals, which include acute alterations in cell metabolism and secretion, and long term changes in cell proliferation and differentiation. CaR is critical to maintenance of systemic calcium levels, by controlling parathyroid PTH secretion and the balance of renal calcium excretion/resorption. Cell-specific variability in CaR signaling may in part be due to interaction(s) of CaR with scaffold proteins and the formation of cell-specific signaling complexes. The cytoskeletal protein filamin A is a scaffold for CaR, required for CaR-mediated activation of MARK signaling, and slowing CaR degradation. Preliminary data suggests CaR interactions with arrestins-1 and -2 modulate intracellular calcium responses and MARK signaling. To understand how protein scaffolds regulate CaR-mediated signaling, we will test the following hypotheses: (1) Does state-dependent arrestin-1 binding regulate CaR responsiveness? (2) Is CaR-mediated MARK signaling organized by filamin A and arrestin-2, and does the signaling pathway include transactivation of the EGF receptor? (3) Does filamin A act as a molecular escort to stabilize cellular CaR levels by protecting CaR from proteasome-mediated degradation? We will combine biochemical approaches with intracellular calcium and/or confocal imaging, using human CaR and mutant and deletion constructs. The proposed experiments will increase our understanding of the role of the protein scaffolds arrestin-1 and -2 and filamin A in enhancing the specificity of CaR signaling. More than 40 mutations in human CaR have been linked to disease, revolutionizing the clinical dissection of parathyroidisms. Allosteric modulators of CaR have clinical utility for treatment of primary hyper- and hypo- parathyroidism, secondary changes in parathyroid function resulting from renal disease, and osteoporosis. CaR stimulates cell proliferation as well as PTHrP secretion, suggesting role for CaR in potentiating the pathophysiological consequences of malignancies. Dysregulation of CaR expression and/or acute or long term signaling may, in part, be the result of altered interactions with scaffold proteins which serve to enhance CaR signaling specificity and to regulate CaR stability. Understand the role of scaffolds in CaR function may provide novel, specific sites for pharmacological intervention in treatment of calcium handling diseases.

描述（由申请人提供）：钙感应受体（CAR）会导致细胞外钙和代谢产物（丁字力的多胺）中的局部变化成内信号，其中包括细胞代谢和分泌的急性改变，以及细胞增殖和分化的长期变化。通过控制甲状旁腺PTH分泌和肾钙排泄/吸收的平衡，CAR对于维持全身钙水平至关重要。 CAR信号传导的细胞特异性变异可能部分是由于与支架蛋白的CAR相互作用以及细胞特异性信号复合物的形成。细胞骨架蛋白丝蛋白A是汽车的支架，是CAR介导的Mark信号激活所必需的，并减慢了CAR降解。初步数据表明，与抑制蛋白1和-2的CAR相互作用调节细胞内钙反应和标记信号传导。为了了解蛋白支架如何调节CAR介导的信号传导，我们将测试以下假设：（1）国家依赖性抑制蛋白-1结合是否调节CAR响应能力？ （2）通过Filamin A和Hustanin-2组织了CAR介导的Mark信号抑制，信号传导途径是否包括EGF受体的反式激活？ （3）Filamin A作为分子伴游是否通过保护CAR免受蛋白酶体介导的降解来稳定细胞汽车水平？我们将使用人类汽车以及突变体和缺失构建体结合生化方法与细胞内钙和/或共聚焦成像。提出的实验将增加我们对蛋白质支架阻碍蛋白1和-2和丝蛋白A在增强CAR信号传导特异性方面的作用的理解。人类汽车中有40多个突变与疾病有关，彻底改变了甲状旁腺功能亢进症的临床解剖。汽车的变构调节剂具有治疗原发性甲状旁腺功能亢进症的临床实用性，肾脏疾病引起的甲状旁腺功能的次要变化以及骨质疏松症。 CAR刺激细胞增殖和PTHRP分泌，这表明CAR在增强恶性肿瘤的病理生理后果中的作用。汽车表达和/或急性或长期信号传导的失调可能部分是与脚手架蛋白相互作用改变的结果，这些蛋白质有助于增强CAR信号特异性并调节CAR稳定性。了解脚手架在汽车功能中的作用可能会为药理干预的新型特定部位提供治疗钙处理疾病的作用。