Glycan Imaging in Intact Rat Hearts and Glycoproteomic Analysis Reveal the Upregulation of Sialylation during Cardiac Hypertrophy
Glycosylation has been implicated in cardiac physiology and pathology. It is therefore of great interest to directly visualize glycans in situ in intact hearts. A interdisciplinary PKU research group from Prof. Xing Chen, Prof. Shiqang Wang and Prof. Jing Zhao’s labs described a chemical approach for direct imaging of newly-synthesized cardiac glycans in rats, based on metabolic labeling with azidosugars followed by chemoselective fluorescence tagging using bioorthogonal chemistry(J. Am. Chem. Soc. DOI: 10.1021/ja508484c). They applied this methodology to visualize the glycosylation during the cardiac pathological process, hypertrophy, which often leads to the heart failure. Their imaging results revealed that the biosynthesis of sialylated glycans is upregulated during cardiac hypertrophy. Furthermore, derivatizing azides with affinity tags allows enrichment and proteomic identification of glycosylated cardiac proteins. Quantitative proteomic analysis identified multiple sialylated proteins that were upregulated during hypertrophy. Their findings demonstrate that sialylation plays an important functional role in mediating hypertrophy progression. The direct visualization of glycans in intact hearts coupled with glycoproteomic analysis is an exciting technical platform that offers a new mechanism for studying how glycosylation regulates the cardiac functions.