Clarifying the signal network of salvianolic acid B using proteomic assay and bioinformatic analysis

Salvianolic acid B (SB) is a natural compound with protective effect against ischemia-reperfusion heart injury. However, the signal network of SB including both direct target proteins and downstream signal-related proteins has not been clarified. In the present study, epidermal growth factor receptor (EGFR) was predicted to be the most possible direct protein target of SB by INVDOCK, a ligand-protein inverse-docking algorithm. Possible signal-related proteins of SB in H9C2 cells, including both under normal condition and under ischemia-reperfusion injury, were searched using 2-DE analysis. Totally, 14 signal-related proteins were found. Finally, signal network from EGFR to the signal-related proteins was established using bioinformatic analysis. Interestingly, 9 of the 14 signal-related proteins could be included in a network together with EGFR through direct interaction or only one intermediate partner. The signal cascade from EGFR to heat shock protein 27 (HSP27) and mitofilin (IMMT, inner membrane mitochondrial protein) might be the most important cascade. The signal network was certified by measuring the binding affinity of SB to EGFR in vitro, the effect of SB on internalization and phosphorylation of EGFR, the effect of SB on viability and proliferation of H9C2 cells, and the expression of inner membrane mitochondrial protein in the presence of EGFR inhibitor AG 1478.