Protein-protein interaction map is a key gateway into liver regeneration

Figure 1 Hepatocyte cell cycle during liver regeneration and clustering algorithm of gene expressions in gene chip during mouse liver regeneration following CCl₄-induced liver injury. Some important genes are activated in the regenerating liver after partial hepatectomy or hepatocellular injury induced by CCl₄. Liver regeneration can be divided into four phases: G0: Corresponds to approximately the first 4 h; G1: Quiescent cells enter the cell cycle during production of hepatocyte growth factor (HGF), epidermal growth factor (EGF), tumor necrosis factor (TNF), etc.; S: Chromosomal DNA is replicated and peak DNA production occurs at approximately 24 h; then, after 48 h or more, the process of regeneration is terminated. The curves following the gene products and the dashed line represent the changes in gene expressions measured in our lab using Gene Chip^® mouse 430 2.0 during liver regeneration following CCl₄-induced liver injury. Changes on the level of gene expression were log2-transformed using signal value at 0 h time-point as baseline. Genes with their expression levels varying at least 2-fold between any two time-points were subjected to hierarchical clustering analysis. TGF: Transforming growth factor; MMP9: Matrix metalloproteinase 9.