Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA,15260.
Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA,15260.
Proc Natl Acad Sci U S A. 2022 Oct 4;119(40):e2204828119. doi: 10.1073/pnas.2204828119. Epub 2022 Sep 26.
Biased G protein-coupled receptor (GPCR) ligands, which preferentially activate G protein or β-arrestin signaling pathways, are leading to the development of drugs with superior efficacy and reduced side effects in heart disease, pain management, and neuropsychiatric disorders. Although GPCRs are implicated in the pathophysiology of Alzheimer's disease (AD), biased GPCR signaling is a largely unexplored area of investigation in AD. Our previous work demonstrated that GPR3-mediated β-arrestin signaling modulates amyloid-β (Aβ) generation and that deficiency ameliorates Aβ pathology . However, -deficient mice display several adverse phenotypes, including elevated anxiety-like behavior, reduced fertility, and memory impairment, which are potentially associated with impaired G protein signaling. Here, we generated a G protein-biased GPR3 mouse model to investigate the physiological and pathophysiological consequences of selective elimination of GPR3-mediated β-arrestin signaling . In contrast to -deficient mice, G protein-biased GPR3 mice do not display elevated anxiety levels, reduced fertility, or cognitive impairment. We further determined that G protein-biased signaling reduces soluble Aβ levels and leads to a decrease in the area and compaction of amyloid plaques in the preclinical AD mouse model. The changes in amyloid pathology are accompanied by robust microglial and astrocytic hypertrophy, which suggest a protective glial response that may limit amyloid plaque development in G protein-biased GPR3 AD mice. Collectively, these studies indicate that GPR3-mediated G protein and β-arrestin signaling produce discrete and separable effects and provide proof of concept for the development of safer GPCR-targeting therapeutics with more directed pharmacological action for AD.
偏向性 G 蛋白偶联受体(GPCR)配体优先激活 G 蛋白或β-arrestin 信号通路,正在推动治疗心脏病、疼痛管理和神经精神疾病的药物的发展,这些药物具有更好的疗效和更少的副作用。尽管 GPCR 与阿尔茨海默病(AD)的病理生理学有关,但偏向性 GPCR 信号在 AD 中是一个很大程度上尚未被探索的研究领域。我们之前的工作表明,GPR3 介导的β-arrestin 信号调节淀粉样蛋白-β(Aβ)的产生,并且缺乏 GPR3 可以改善 Aβ 病理学。然而,缺乏 GPR3 的小鼠表现出多种不良表型,包括焦虑样行为增加、生育能力降低和记忆障碍,这可能与 G 蛋白信号受损有关。在这里,我们生成了一种偏向性 G 蛋白的 GPR3 小鼠模型,以研究选择性消除 GPR3 介导的β-arrestin 信号对生理和病理生理的影响。与缺乏 GPR3 的小鼠不同,偏向性 G 蛋白的 GPR3 小鼠不会表现出焦虑水平升高、生育能力降低或认知障碍。我们进一步确定,偏向性 G 蛋白信号会降低可溶性 Aβ水平,并导致临床前 AD 小鼠模型中淀粉样斑块的面积和致密性降低。淀粉样蛋白病理学的变化伴随着小胶质细胞和星形胶质细胞的强烈肥大,这表明保护性胶质反应可能限制了偏向性 GPR3 AD 小鼠中淀粉样斑块的发展。总之,这些研究表明,GPR3 介导的 G 蛋白和β-arrestin 信号产生离散且可分离的效应,并为开发更具靶向性药理学作用的更安全的 GPCR 靶向治疗药物提供了概念验证,以治疗 AD。