Introduction: NASH is a chronic liver disease often associated with type 2 diabetes. It sometimes progresses to more serious conditions such as liver fibrosis and hepatocellular carcinoma (HCC). Therapeutic agents for NASH have not yet been developed, and an animal model with high clinical correlation is required. The STAM mouse is a NASH model mouse with a background of type 2 diabetes. This mouse model shows the same pathological progression as human NASH patients, and has been used for the evaluation of many drug candidates, as well as basic research. However the gene profile, including mutations, has not been elucidated in this model. In this study, we analyzed the RNA-seq data of STAM mice at each pathological stage and examined the clinical correlation at the gene level.
Methods: NASH was induced in male mice by a single injection of streptozotocin solution 2 days after birth and feeding with high fat diet after 4 weeks of age. The mice were sacrificed and livers collected from each disease phase. RNA-Seq libraries were prepared by NEB NEXT Directional Ultra RNA Library Prep Kit (Illumina). The libraries were sequenced on Novaseq (Illumina), and the reads were aligned to mouse genome references using HISAT2. RNA-seq data analysis Sequence reads (150-bp paired read) were aligned to the mouse reference genome (GRCm38/mm10) with HISAT2 (version: 2.1.0) with default parameters.
Results: First, the gene expression of the canonical pathway in NASH progression from steatosis to hepatocellular carcinoma was analyzed. Increased expression was observed in CCL2, TLR4, HSP47, αSMA, c-Myc, and cyclin D1. Since it has been reported that genetic traits are involved in the development of NASH-HCC, we next analyzed the genetic mutations in the STAM mice. The number of individuals showing mutations in Mtor, involved in Insulin signaling, increases as the disease progresses, especially in the HCC phase.
Conclusion: These results indicated a clinical correlation of gene profiles in the STAM mouse.
L. P. Bui: Employee; Self; SMC Laboratories Inc. Y. Sakakibara: Employee; Self; SMC. R. Tanaka: Employee; Self; SMC Laboratories Inc. E. H. Pigney: Employee; Self; SMC Laboratories, Inc. T. Hashiguchi: Employee; Self; SMC laboratories, Inc.