Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA.
Nutritional Sciences Department, College of Human Sciences, Texas Tech University, 1301 Akron Ave, Lubbock, TX 79409, USA.
Cells. 2022 Feb 19;11(4):733. doi: 10.3390/cells11040733.
The purpose of our study is to investigate early cellular, molecular, morphological and behavioral changes in humanized amyloid-beta-knock-in (hAbKI) mice. Using seven-month-old homozygous hAbKI mice, we studied behavioral phenotype parameters, including spatial learning and memory (Morris Water Maze), locomotor activity (open field), working memory (Y-maze) and motor coordination (rotarod); mRNA abundance, protein levels, soluble amyloid-beta 40 and 42 levels and regional immunoreactivities of key markers of mitochondrial dynamics, mitochondrial biogenesis, synaptic health, mitophagy and autophagy; mitochondrial function and using transmission electron microscopy & Golgi-Cox staining, we assessed mitochondrial morphology and dendritic spines. Our extensive behavioral analysis revealed that seven-month-old hAbKI mice showed impairments in motor coordination, reduced locomotor and exploration activities, impairments in working memory and spatial learning and memory. Our mRNA and protein analyses revealed the increased expression of mitochondrial-fission genes and reduced expression of mitochondrial-fusion, mitochondrial-biogenesis, synaptic, autophagy and mitophagy genes in seven-month-old hAbKI mice. An immunofluorescence analysis revealed altered immunoreactivities and agreed with the immunoblot results. Transmission-electron-microscopy data revealed increased mitochondrial fragmentation and reduced mitochondrial length in both hippocampal and cortical tissues of seven-month-old hAbKI mice and mitochondrial function defective. A Golgi-Cox-staining analysis revealed reduced dendritic spines in both cerebral cortices and hippocampi of hAbKI mice. Soluble amyloid-beta (1-40 and 1-42) were detected in three-month-old hAbKI mice and progressively increased in seven-month-old mice. These observations suggest that the human amyloid-beta peptide is sufficient to cause behavioral, mitochondrial, synaptic and ultrastructural changes in seven-month-old hAbKI mice. Our study findings also suggest that hAbKI mice might serve as a model for preclinical studies of preventive therapies.
我们研究的目的是研究人源淀粉样β敲入（hAbKI）小鼠的早期细胞、分子、形态和行为变化。我们使用 7 月龄的纯合 hAbKI 小鼠，研究了行为表型参数，包括空间学习和记忆（水迷宫）、运动活性（旷场）、工作记忆（Y 迷宫）和运动协调（转棒）；mRNA 丰度、蛋白质水平、可溶性淀粉样β 40 和 42 水平以及线粒体动力学、线粒体生物发生、突触健康、线粒体自噬和自噬的关键标志物的区域免疫活性；线粒体功能，并使用透射电子显微镜和高尔基 Cox 染色评估线粒体形态和树突棘。我们广泛的行为分析表明，7 月龄的 hAbKI 小鼠表现出运动协调障碍、运动活性和探索性活动减少、工作记忆和空间学习和记忆受损。我们的 mRNA 和蛋白质分析表明，7 月龄的 hAbKI 小鼠中，线粒体分裂基因的表达增加，而线粒体融合、线粒体生物发生、突触、自噬和线粒体自噬基因的表达减少。免疫荧光分析显示，免疫反应性发生改变，与免疫印迹结果一致。透射电镜数据显示，7 月龄 hAbKI 小鼠海马和皮质组织中线粒体碎片化增加，线粒体长度减少，线粒体功能受损。高尔基 Cox 染色分析显示 hAbKI 小鼠大脑皮质和海马中的树突棘减少。在 3 月龄的 hAbKI 小鼠中检测到可溶性淀粉样β（1-40 和 1-42），并在 7 月龄的小鼠中逐渐增加。这些观察结果表明，人类淀粉样β肽足以引起 7 月龄 hAbKI 小鼠的行为、线粒体、突触和超微结构变化。我们的研究结果还表明，hAbKI 小鼠可能成为预防治疗的临床前研究模型。
