Amd1-skp2 cascade regulates hepatocyte proliferation during liver growth and hepatocellular carcinoma development in zebrafish

Rapid hepatocyte proliferation is a common characteristic of liver growth in early liver development and hepatocellular carcinoma (HCC). Clarifying the mechanism how liver growth is regulated in development would benefit studying HCC progress. Although many genes have been reported to be involved in liver growth during early development, the mechanism underlying liver growth is far from being elucidated. Here we found that the liver undergoes rapid growth from 2dpf to 5dpf in zebrafish. Comparing the transcriptome for different staged hepatocytes identified 813 hepatocyte enriched genes at 3 dpf. Among them, S-adenosylmethionine decarboxylase proenzyme (AMD1) had not been previously reported to be involved in liver development. Our study further confirmed that amd1 was highly enriched in hepatocytes during liver rapid growth and that amd1 mutation inhibited liver growth mainly by repressing hepatocyte proliferation. Mechanistically, amd1 loss of function downregulated the expression of skp2, and skp2 is required for amd1 to regulate hepatocyte proliferation. Furthermore, the role of Amd1-Skp2 cascade in regulating hepatocyte proliferation was also conserved in a zebrafish HCC model. In conclusion, our study systematically identified some uncharacterized genes possibly being involved in regulating liver growth during zebrafish development, and revealed the role of amd1-skp2 cascade in regulating hepatocyte proliferation during liver growth and HCC progression. This work also provided a database which would benefit elucidating the mechanism how hepatocyte proliferation is regulated during liver growth and HCC progress.