Proteomic analysis of L6 myoblasts treated with C-terminal transgelin peptides

To investigate bioactivity of peptides identified in human plasma, we treated L6 myoblasts in vitro with a synthetic C-terminal peptide from TAGLN spanning amino acids 179-200, or a synthetic C-terminal peptide from TAGLN2 spanning amino acids 178-199 (1 µg/mL; 7 days), and compared the treatments to control myoblasts cultured for the same amount of time with the addition of only PBS. Proteomic analysis by single-shot nanoUHPLC-MS/MS was performed on four biological replicates and quantification performed by LFQ. A total of 6,095 proteins were identified with 4,710 quantified in at least three biological replicates (Supplemental Table S4). A total of 222 and 307 proteins were regulated by the TAGLN and TAGLN2 peptides relative to the control treatments, respectively, with 61 proteins co-regulated by both TAGLN and TAGLN2 (P<0.05; two-sample t-test with Benjamini-Hochberg correction) (Figure 3G).