American journal of physiology. Renal physiology, 2020.319(5), F809-F821, DOI: https://doi.org/10.1152/ajprenal.00037.2020

RNA-seq profiling of microdissected glomeruli identifies potential biomarkers for human IgA nephropathy

Park S, Yang S;Jeong C;Moon K;Kim D;Joo K;Kim Y;Lee J;Lee H

Abstract

Few studies have examined gene-expression changes occurring in the glomeruli of immunoglobulin A nephropathy (IgAN) using a sensitive tranomic profiling method such as RNA sequencing (RNA-seq). We collected glomeruli from biopsy specimens from IgAN patients with relatively preserved kidney function (eGFR ≥ 60 mL/min/1.73 m2 and urine protein-to-creatinine ratio < 3 g/g) and from normal kidney cortices by hand microdissection and performed RNA-seq. Differentially expressed genes (DEG) were identified, and gene63 ontology term annotation and pathway analysis were performed. Immunohistochemical labeling and primary mesangial cell cultures were performed to confirm the findings of RNA seq analysis. Fourteen IgAN patients and ten controls were included in this study. Glomerulus specific genes were highly abundant. Principal component analysis showed clear separation between the IgAN and control groups. There were 2,497 DEGs, of which 1,380 were upregulated and 1,117 were downregulated (false discovery rate < 0.01). The enriched gene ontology terms included motility/migration, protein/vesicle transport, and immune system, and the kinase binding was the molecular function overrepresented in IgAN. B cell signaling, chemokine signal transduction, and FcγR-mediated phagocytosis were the canonical pathways overrepresented. In vitro studies confirmed that spleen tyrosine kinase (SYK), reported as upregulated in the IgAN tranome, was also upregulated in the glomeruli from an independent set of IgAN patients and that treatment with patient-derived IgA1 increased the expression of SYK in mesangial cells. In conclusion, the tranomic profiling of IgAN glomerulus provide insights for intraglomerular pathophysiology of IgAN before reaching profound kidney dysfunction. SYK may have a pathogenetic role in IgAN.

• DOI: https://doi.org/10.1152/ajprenal.00037.2020
• ISBN or ISSN: 1931-857X

• 본 연구는 질병관리본부 연구개발과제연구비를 지원받아 수행되었습니다.
• This research was supported by a fund by Research of Korea Centers for Disease Control and Prevention.