The expression of C‐terminal phosphorylated Smad3 (pSmad3C) is down‐regulated with the progression of liver disease. Thus, we hypothesized that pSmad3C expression may be negatively related to liver disease. To develop novel therapeutic strategies, a suitable animal model is required that will allow researchers to study the effect of Smad3 domain‐specific phosphorylation on liver disease progression. The current study aimed to construct a new mouse model with the Smad3 C‐terminal phosphorylation site mutation and to explore the effects of this mutation on CCl₄‐induced inflammation. Smad3 C‐terminal phosphorylation site mutant mice were generated using TetraOne™ gene fixed‐point knock‐in technology and embryonic stem cell microinjection. Resulting mice were identified by genotyping, and the effects on inflammation were explored in the presence or absence of CCl₄. No homozygous mice were born, indicating that the mutation is embryonic lethal. There was no significant difference in liver phenotype and growth between the wild‐type (WT) and heterozygous (HT) mice in the absence of reagent stimulation. After CCl₄‐induced acute and chronic liver damage, liver pathology, serum transaminase (ALT/AST) expression and levels of inflammatory factors (IL‐6/TNF‐α) were more severely altered in HT mice than in WT mice. Furthermore, pSmad3C protein levels were lower in liver tissue from HT mice. These results suggest that Smad3 C‐terminal phosphorylation may have a protective effect during the early stages of liver injury. In summary, we have generated a new animal model that will be a novel tool for future research on the effects of Smad3 domain‐specific phosphorylation on liver disease progression.

中文翻译：

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Smad3基因的C末端磷酸化位点突变加重了CCl4诱导的小鼠炎症。

C末端磷酸化Smad3（pSmad3C）的表达随着肝脏疾病的进展而下调。因此，我们假设pSmad3C表达可能与肝脏疾病负相关。为了开发新的治疗策略，需要一种合适的动物模型，该模型将使研究人员能够研究Smad3结构域特异性磷酸化对肝病进展的影响。当前的研究旨在构建具有Smad3 C末端磷酸化位点突变的新小鼠模型，并探讨该突变对CCl _4的影响引起的炎症。使用TetraOne™基因定点敲入技术和胚胎干细胞显微注射产生了Smad3 C末端磷酸化位点突变小鼠。通过基因分型鉴定所得小鼠，并在存在或不存在CCl _4的情况下探索对炎症的影响。没有纯合小鼠出生，表明该突变是胚胎致死性的。在没有试剂刺激的情况下，野生型（WT）和杂合型（HT）小鼠的肝表型和生长无显着差异。CCl _4之后与野生型小鼠相比，HT小鼠引起的急性和慢性肝损伤，肝脏病理学，血清转氨酶（ALT / AST）表达和炎性因子（IL-6 /TNF-α）水平变化更为严重。此外，HT小鼠肝脏组织中的pSmad3C蛋白水平较低。这些结果表明，Smad3 C末端磷酸化在肝损伤的早期可能具有保护作用。总而言之，我们已经产生了一种新的动物模型，它将成为未来研究Smad3结构域特异性磷酸化对肝病进展的影响的新型工具。