Proteomics Analysis of Hepatocyte Proliferation Regulated by FGF, PDGF, Insulin, Oncostatin M and Interleukin 2 Signaling Pathways during Rat Liver Regeneration

Liver regeneration (LR) is of great clinical significance in various liver-associated diseases. LR after partial hepatectomy (PH) can be divided into three distinct phases: priming/initiation, proliferation, and termination. To investigate the mechanism of cell proliferation during rat LR, two-dimensional fluorescence difference gel electrophoresis (2D-DIGE) combined with mass spectrometry was applied to examine the changes in the proteome that occurred at 10 time points after PH. Meanwhile, several proteins were selected to validate the protein levels by Western blot. The results showed that 5,631 proteins were significantly changed in rat LR when compared with normal control. Among them, 2,168 proteins showed significant or extremely significant differences when compared with sham operation (SO) by F-test, which were regarded as liver regeneration-related proteins. Gene Ontology annotation and Ingenuity Pathway Analysis 9.0 (IPA) software analysis indicated that 279 liver regeneration-related proteins were involved in signaling pathways which regulate cell proliferation, and 506 proteins participated in cell proliferation. Analysis of protein synergy by spectral function Ep(t) showed that signal transduction activity of FGF pathway at 2 h, PDGF, insulin and oncostatin M pathways at 12 h, interleukin 2 pathway at 2-36 h were significantly enhanced, and cell proliferation activity was also enhanced at 2-36 h in rat LR. Protein network analysis by IPA software and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway showed that phospholipase C gamma 2 (PLCG2) was located in the central node of the above-mentioned signaling pathways, and was up-regulated at 2-168 h in rat LR, suggesting that these signaling pathways might promote hepatocyte proliferation in the initial and progressive stages of rat LR via PLCG2.