Department of Biomedical Sciences, College of Medicine, Florida State University, 1115 West Call Street, Tallahassee, FL, 32306, USA.
Keck School of Medicine of University of Southern California, 1450 Biggy Street, NRT 4510, Los Angeles, CA, 90033, USA.
Sci Rep. 2019 Jan 23;9(1):326. doi: 10.1038/s41598-018-36841-y.
Fibrosis is characterized by excessive production of type I collagen. Biosynthesis of type I collagen in fibrosis is augmented by binding of protein LARP6 to the 5' stem-loop structure (5'SL), which is found exclusively in type I collagen mRNAs. A high throughput screen was performed to discover inhibitors of LARP6 binding to 5'SL, as potential antifibrotic drugs. The screen yielded one compound (C9) which was able to dissociate LARP6 from 5' SL RNA in vitro and to inactivate the binding of endogenous LARP6 in cells. Treatment of hepatic stellate cells (liver cells responsible for fibrosis) with nM concentrations of C9 reduced secretion of type I collagen. In precision cut liver slices, as an ex vivo model of hepatic fibrosis, C9 attenuated the profibrotic response at 1 μM. In prophylactic and therapeutic animal models of hepatic fibrosis C9 prevented development of fibrosis or hindered the progression of ongoing fibrosis when administered at 1 mg/kg. Toxicogenetics analysis revealed that only 42 liver genes changed expression after administration of C9 for 4 weeks, suggesting minimal off target effects. Based on these results, C9 represents the first LARP6 inhibitor with significant antifibrotic activity.
纤维化的特征是 I 型胶原的过度产生。纤维化中 I 型胶原的生物合成通过蛋白 LARP6 与 5' 茎环结构（5'SL）的结合而增强，5'SL 仅存在于 I 型胶原 mRNAs 中。进行了高通量筛选以发现抑制 LARP6 与 5'SL 结合的抑制剂，作为潜在的抗纤维化药物。该筛选产生了一种化合物（C9），它能够在体外将 LARP6 从 5'SL RNA 上解离，并使细胞内内源性 LARP6 的结合失活。以纳摩尔浓度的 C9 处理肝星状细胞（负责纤维化的肝细胞）可减少 I 型胶原的分泌。在精密切割的肝切片中，作为肝纤维化的体外模型，C9 在 1 μM 时可减轻促纤维化反应。在肝纤维化的预防性和治疗性动物模型中，当以 1mg/kg 给药时，C9 可预防纤维化的发展或阻止正在进行的纤维化的进展。毒理学分析表明，仅在给予 C9 4 周后，有 42 个肝脏基因的表达发生变化，提示脱靶效应最小。基于这些结果，C9 代表了具有显著抗纤维化活性的第一个 LARP6 抑制剂。
