Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.
Genetics and Genomics Graduate Program, Baylor College of Medicine, Houston, Texas, USA.
Hepatology. 2023 Nov 1;78(5):1337-1351. doi: 10.1097/HEP.0000000000000380. Epub 2023 Apr 7.
Paucity of intrahepatic bile ducts (BDs) is caused by various etiologies and often leads to cholestatic liver disease. For example, in patients with Alagille syndrome (ALGS), which is a genetic disease primarily caused by mutations in jagged 1 ( JAG1) , BD paucity often results in severe cholestasis and liver damage. However, no mechanism-based therapy exists to restore the biliary system in ALGS or other diseases associated with BD paucity. Based on previous genetic observations, we investigated whether postnatal knockdown of the glycosyltransferase gene protein O -glucosyltransferase 1 ( Poglut1) can improve the ALGS liver phenotypes in several mouse models generated by removing one copy of Jag1 in the germline with or without reducing the gene dosage of sex-determining region Y-box 9 in the liver.
Using an ASO established in this study, we show that reducing Poglut1 levels in postnatal livers of ALGS mouse models with moderate to profound biliary abnormalities can significantly improve BD development and biliary tree formation. Importantly, ASO injections prevent liver damage in these models without adverse effects. Furthermore, ASO-mediated Poglut1 knockdown improves biliary tree formation in a different mouse model with no Jag1 mutations. Cell-based signaling assays indicate that reducing POGLUT1 levels or mutating POGLUT1 modification sites on JAG1 increases JAG1 protein level and JAG1-mediated signaling, suggesting a likely mechanism for the observed in vivo rescue.
Our preclinical studies establish ASO-mediated POGLUT1 knockdown as a potential therapeutic strategy for ALGS liver disease and possibly other diseases associated with BD paucity.
肝内胆管（BDs）稀少由多种病因引起，常导致胆汁淤积性肝病。例如，在 Alagille 综合征（ALGS）患者中，该病主要由 Jagged 1（JAG1）基因突变引起，BD 稀少常导致严重的胆汁淤积和肝损伤。然而，目前尚无针对 ALGS 或其他与 BD 稀少相关疾病的基于机制的治疗方法来恢复胆管系统。基于先前的遗传观察，我们研究了在Jag1 基因在生殖细胞中缺失一个拷贝的几种小鼠模型中，或在不减少肝脏性别决定区 Y 框 9 基因剂量的情况下，敲低糖基转移酶基因蛋白 O-葡萄糖基转移酶 1（Poglut1）是否可以改善 ALGS 肝脏表型。
利用本研究中建立的 ASO，我们表明，在具有中度至重度胆道异常的 ALGS 小鼠模型的出生后肝脏中降低 Poglut1 水平，可以显著改善 BD 发育和胆管树形成。重要的是，ASO 注射可预防这些模型中的肝损伤，而无不良反应。此外，ASO 介导的 Poglut1 敲低可改善无 Jag1 突变的另一种小鼠模型中的胆管树形成。基于细胞的信号转导测定表明，降低 POGLUT1 水平或突变 POGLUT1 在 JAG1 上的修饰位点会增加 JAG1 蛋白水平和 JAG1 介导的信号转导，提示观察到的体内挽救的可能机制。
我们的临床前研究确立了 ASO 介导的 Poglut1 敲低作为治疗 ALGS 肝脏疾病和可能其他与 BD 稀少相关疾病的潜在治疗策略。
