Proteomic analysis of 3T3-L1 preadipocytes having a higher cell proliferation rate after treatment with low-molecular-weight silk fibroin peptides

Objectives: Previous studies have reported that fibroin peptides can be used in a new strategy for development of anti‐diabetic peptide drugs. In this study, we separated silk fibroin hydrolysates (SFH) containing silk fibroin peptides into four components according to their molecular weight and tested the effects of these together with three synthetic silk fibroin hexapeptides GAGAGS, GAGAGY, GAGAGA on cell proliferation of 3T3‐L1 preadipocytes. The aim of this study was to investigate protein expression profiles of 3T3‐L1 preadipocytes and those treated with SFH component Fraction I and the synthetic silk fibroin hexapeptide GAGAGS to be able to elucidate difference in protein expression between the 3T3‐L1 preadipocytes and those treated with fibroin peptides Fraction I and GAGAGS. Materials and methods: SFH was separated by dialysis. MTT assays were performed to test effects of SFH components and synthetic silk fibroin hexapeptides on 3T3‐L1 preadipocyte proliferation. We generated proteome maps using two‐dimensional gel electrophoresis and analysed them by peptide mass fingerprinting. Results: GAGAGS and peptide mixtures, Fraction I and Fraction II, had significant effect in promoting 3T3‐L1 preadipocyte proliferation. In the proteomic analysis, 73 protein spots were successfully identified, including 15 which were differentially expressed. Conclusions: Our results show that some silk fibroin peptides of low molecular weight SFH and hexapeptide GAGAGS affected 3T3‐L1 preadipocyte proliferation.