Quantitative proteomic analysis to identify differentially expressed proteins in the persistent atrial fibrillation using TMT coupled with nano-LC-MS/MS.

Persistent atrial fibrillation (PeAF) is a progressive cardiovascular disease with a high risk for most patients after diagnosis. Poor molecular description of PeAF has led to unsatisfactory interpretation of the pathogenesis of it, resulting in the lack of effective treatments. The aim of the present study was to find several new potential biomarkers for early prevention, diagnosis and treatment of this disease and explore the underlying molecular mechanisms. An absolute quantitation Tandem Mass Tag (TMT)-liquid chromatography-tandem mass spectrometry (LC-MS/MS) approach was applied to identify differentially expressed proteins (DEPs) in left atrial appendage. Totally, 4682 proteins were identified and 4159 proteins were quantified. Compared with control subjects, 118 DEPs (85 upregulated proteins and 33 downregulated proteins) were identified in the atrial tissues of PeAF patients. Using String software, a regulatory network containing 87 nodes and 244 edges was built, and the functional enrichment showed that DEPs were predominantly involved in protein digestion and absorption, regulation of metabolism and focal adhesion. Four proteins, collagen 1 (COL-I), collagen 2 (COL-II), ras-related protein 1 (RAP1) and leucine-rich alpha-2-glycoprotein 1 (LRG1) were selected for validation using Western blot analysis to distinguish PeAF patients and control subjects. The present results provide a comprehensive understanding of the pathophysiological mechanisms of PeAF and the validated biomarkers for the diagnosis of PeAF, which facilitate the development of therapeutic targets.