Human hepatic micropeptide LC-MS/MS

Considering the large number of sORFs in eukaryotic cells, micropeptides might be a long-neglected potential resource pool. However, due to the methodological limitations of micropeptide identification, tumor-related micropeptides have not been comprehensively identified, and their functional mechanisms in tumor progression remained largely uncharacterized. In the present study, we systematically identified micropeptides within HCC tissue samples based on mass spectrometry (MS) detection. By producing a high-coverage micropeptide sequencing reference library and devising an alternative ultrafiltration-concentrated tandem mass spectrometry assay, 1532 unannotated micropeptides (with no overlap with previously annotated CDSs) were successfully identified. It turned out that 81.5% of these micropeptides derived from novel ORFs and 70% of them used non-ATG start codons. Noteworthy, 5.3% of micropeptides were derived from lncRNAs, which are previously considered incapable of protein-coding. Our systematic screening of liver cancer-related micropeptides and in-depth exploration of their functions will improve our understanding of HCC pathogenesis and molecular targeted therapy.