Division of Respiratory Disease, The Fourth Affiliated Hospital of Harbin Medical University, Harbin, China.
Department of Histology and Embryology, Harbin Medical University, Harbin, China.
Lab Invest. 2018 Apr;98(4):512-524. doi: 10.1038/s41374-017-0019-y. Epub 2018 Jan 12.
Familial amyloidotic polyneuropathy is an autosomal dominant disorder caused by a point mutation in the transthyretin (TTR) gene. The process of TTR amyloidogenesis begins with rate-limiting dissociation of the TTR tetramer. Thus, the TTR stabilizers, such as Tafamidis and Diflunisal, are now in clinical trials. Mouse models will be useful to testing the efficacy of these drugs. Although several mouse models have been generated, they all express mouse Rbp4. Thus, human TTR associates with mouse RBP4, resulting in different kinetic and thermodynamic stability profiles of TTR tetramers. To overcome this problem, we previously produced humanized mouse strains at both the TTR and Rbp4 loci (Ttr , Ttr , and Rbp4 ). By mating these mice, we produced double-humanized mouse strains, Ttr :Rbp4 and Ttr :Rbp4 . We used conventional transgenic mouse strains on a wild-type (Ttr :Tg[6.0hTTRMet30]) or knockout Ttr background (Ttr:Tg[6.0hTTRMet30]) as reference strains. The double-humanized mouse showed 1/25 of serum hTTR and 1/40 of serum hRBP4 levels. However, amyloid deposition was more pronounced in Ttr :Rbp4 than in conventional transgenic mouse strains. In addition, a similar amount of amyloid deposition was also observed in Ttr :Rbp4 mice that carried the wild-type human TTR gene. Furthermore, amyloid deposition was first observed in the sciatic nerve without any additional genetic change. In all strains, anti-TTR antibody-positive deposits were found in earlier age and at higher percentage than amyloid fibril deposition. In double-humanized mice, gel filtration analysis of serum revealed that most hTTR was free of hRBP4, suggesting importance of free TTR for amyloid deposition.
家族性淀粉样多发性神经病是一种常染色体显性疾病，由转甲状腺素蛋白（TTR）基因的点突变引起。TTR 淀粉样变性的过程始于 TTR 四聚体的限速解离。因此，TTR 稳定剂，如 Tafamidis 和 Diflunisal，目前正在临床试验中。小鼠模型将有助于测试这些药物的疗效。尽管已经产生了几种小鼠模型，但它们都表达小鼠 Rbp4。因此，人 TTR 与小鼠 Rbp4 结合，导致 TTR 四聚体的动力学和热力学稳定性谱不同。为了解决这个问题，我们之前在 TTR 和 Rbp4 基因座上产生了人源化小鼠品系（Ttr , Ttr , 和 Rbp4 ）。通过交配这些小鼠，我们产生了双人类化小鼠品系，Ttr :Rbp4 和 Ttr :Rbp4 。我们使用传统的转基因小鼠品系作为野生型（Ttr :Tg[6.0hTTRMet30]）或敲除 Ttr 背景（Ttr:Tg[6.0hTTRMet30]）作为参考品系。双人类化小鼠的血清 hTTR 水平为 1/25，血清 hRBP4 水平为 1/40。然而，Ttr :Rbp4 中的淀粉样沉积比传统的转基因小鼠品系更为明显。此外，在携带野生型人 TTR 基因的 Ttr :Rbp4 小鼠中也观察到了类似数量的淀粉样沉积。此外，在没有任何其他遗传改变的情况下，首先在坐骨神经中观察到淀粉样沉积。在所有品系中，抗 TTR 抗体阳性沉积物的出现年龄较早，百分比高于淀粉样纤维沉积。在双人类化小鼠中，血清的凝胶过滤分析显示，大多数 hTTR 不含 hRBP4，这表明游离 TTR 对淀粉样沉积很重要。
