Study of Urinary Glycoproteomic Composition of IgA Nephropathy

Liu Junjie; Zhang Jiong; Zhou Hongli

Abstract：Objective To explore the potential biological information of urinary glycated proteins that may be related to IgA ne-phropathy(IgAN)by using urinary glycoproteomics,which may provide biomarkers for the diagnosis of IgAN.Methods Liquid chromatography-tandem mass spectrometry(LC-MS/MS)was used to detect and compare the urinary glycoproteome of IgAN patients(n=3)and healthy controls(n=3)in data dependent acquisition(DDA)mode.The differentially expressed glycosylation modified proteins in the urine of IgAN patients were identified and analyzed by gene ontology(GO)analysis and Kyoto Encyclopedia of Genes and Genomes(KEGG),and their mutual correlation was analyzed by network interaction map.Finally,combined with the current re-search status,the possible role of differential glycoproteins in the diagnosis and prognosis of IgAN was explored.Results(1)Com-pared with the healthy control group,39 proteins were up-regulated in the urine of IgAN patients,including 11 specifically up-regu-lated proteins;a total of 149 differentially down-regulated proteins were identified,including 22 specifically down-regulated proteins;(2)PPI analysis showed that 140 differently expressed proteins had direct or indirect interactions.GO functional enrichment analysis of each differential protein showed that the differential glycoproteins were related to cell component organization,regulation of cell growth,protein binding,O-acyltransferase activity,polysaccharide binding,insulin-like growth factor binding and anchoring.A-mong them,cell adhesion molecules and metabolism-related cell functions were significantly enriched(P<0.05).The differently ex-pressed proteins involved in these signaling pathways were mainly distributed in the extracellular matrix and cell membrane.KEGG en-richment showed that differential glycoproteins were involved in the biological pathways,including cell adhesion molecules,adipokine signaling pathway,mTOR signaling pathway,cholesterol metabolism and ECM-receptor interaction;(3)the differently expressed proteins CCL25,PD-L1,HLA-DRB1,IL7R,CP,AFM and WDR82 were highly connected in PPI interaction analysis map.These urine differentially expressed proteins were involved in KEGG record such as adipokine signaling pathway,mTOR signaling pathway and cholesterol metabolism pathway,cell adhesion molecules,P53 signaling pathway,Notch signaling pathway,Hedgehog signaling pathway,and ECM-receptor interaction pathway.Conclusion(1)There is a significant difference in the expression level of urinary glycoprotein between IgA nephropathy patients and healthy people;(2)GO and KEGG analysis revealed that urinary differential gly-coproteins in patients with IgA nephropathy were involved in a variety of biological functions and pathways related to IgA nephropathy.Urinary glycoproteomics based on UHPLC-MS/MS mass spectrometry may be another choice for the diagnosis of IgA nephropathy;(3)potential biomarkers for IgA nephropathy diagnosis may include,but are not limited to,CCL25,PD-L1,HLA-DRB1,IL7R,CP,AFM,and WDR82.