Increase of hepatic fat accumulation by liver specific expression of Hepatitis B virus X protein in zebrafish.
The pathogenesis of fatty liver disease remains largely unknown. Here, we assessed the importance of hepatic fat accumulation on the progression of hepatitis in zebrafish by liver specific expression of Hepatitis B virus X protein (HBx). Transgenic zebrafish lines, GBXs, which selectively express the GBx transgene (GFP-fused HBx gene) in liver, were established. GBX Liver phenotypes were evaluated by histopathology and molecular analysis of fatty acid (FA) metabolism-related genes expression. Most GBXs (66-81%) displayed obvious emaciation starting at 4 months old. Over 99% of the emaciated GBXs developed hepatic steatosis or steatohepatitis, which in turn led to liver hypoplasia. The liver histology of GBXs displayed steatosis, lobular inflammation, and balloon degeneration, similar to non-alcoholic steatohepatitis (NASH). Oil red O stain detected the accumulation of fatty droplets in GBXs. RT-PCR and Q-rt-PCR analysis revealed that GBx induced hepatic steatosis had significant increases in the expression of lipogenic genes, C/EBP-alpha, SREBP1, ChREBP and PPAR-gamma, which then activate key enzymes of the de novo FA synthesis, ACC1, FAS, SCD1, AGAPT, PAP and DGAT2. In addition, the steatohepatitic GBX liver progressed to liver degeneration and exhibited significant differential gene expression in apoptosis and stress. The GBX models exhibited both the genetic and functional factors involved in lipid accumulation and steatosis-associated liver injury. In addition, GBXs with transmissible NASH-like phenotypes provide a promising model for studying liver disease.
Shieh
Yun-Sheng
YS
Institute of Bioscience and Biotechnology, National Taiwan Ocean University, Keelung, Taiwan.
Chang
Yin-Shan
YS
Hong
Jiann-Ruey
JR
Chen
Li-Je
LJ
Jou
Luen-Kuang
LK
Hsu
Chia-Chun
CC
Her
Guor Mour
GM
D000818:Animals; D030801:Animals, Genetically Modified; D017209:Apoptosis / Q000235:genetics; D004195:Disease Models, Animal; D005227:Fatty Acids / Q000096:biosynthesis* / Q000235:genetics; D005234:Fatty Liver / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D006515:Hepatitis B virus; D008099:Liver / Q000378:metabolism* / Q000473:pathology; D015534:Trans-Activators / Q000096:biosynthesis* / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D054334:Viral Regulatory and Accessory Proteins; D015027:Zebrafish / Q000235:genetics / Q000378:metabolism*
D005227:Fatty Acids; D015534:Trans-Activators; D014157:Transcription Factors; D054334:Viral Regulatory and Accessory Proteins; C057628:hepatitis B virus X protein