RNA-Seq analysis of glycosylation related gene expression in Streptozotocin-induced diabetic rat kidney inner medulla

• Type of Material: Article
• Authors: Xiaoqian Qian, Emory University; Xuechen Li, Emory University; Titilayo Ilori, Emory University; Janet Klein, Emory University; Rebecca P. Hughey, University of Pittsburgh; Cong-jun Li, United States Department of Agriculture - Agricultural Research Service; Abdel A. Alli, Emory University; Zhengyu Guo, Texas A&M University; Peng Yu, Texas A&M University; Xiang Song, Harbin Medical University; Guangping Chen, Emory University
• Language: English
• Date: 2013-04-01
• Publisher: Federation of American Society of Experimental Biology (FASEB)
• Publication Version: Final Published Version
• Copyright Statement: © 2015 Qian, Li, Ilori, Klein, Hughey, Li, Alli, Guo, Yu, Song and Chen.
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.3389/fphys.2015.00274
• Title of Journal or Parent Work: FASEB Journal
• ISSN: 0892-6638
• Volume: 27
• Grant/Funding Information: Heilongjiang Science and Technology funding LBH-Q13113 (to XS).; Chinese National Natural Science Foundation Project 81300248 (to XS); This work was supported by NIH grants R01-DK087838 (to GC), DK054787 (to RPH)
• Keywords: urinary concentration; Illumina; fucosylation; diabetes; gene expression; sialylation
• Research Categories: Biology, Cell; Health Sciences, Medicine and Surgery; Computer Science

Abstract

The UT-A1 urea transporter is crucial to the kidney's ability to generate concentrated urine. Native UT-A1 from kidney inner medulla (IM) is a heavily glycosylated protein with two glycosylation forms of 97 and 117 kDa. In diabetes, UT-A1 protein abundance, particularly the 117 kD isoform, is significantly increased corresponding to an increased urea permeability in perfused IM collecting ducts, which plays an important role in preventing the osmotic diuresis caused by glucosuria. However, how the glycan carbohydrate structure change and the glycan related enzymes regulate kidney urea transport activity, particularly under diabetic condition, is largely unknown. In this study, using sugar-specific binding lectins, we found that the carbohydrate structure of UT-A1 is changed with increased amounts of sialic acid, fucose, and increased glycan branching under diabetic conditions. These changes were accompanied by altered UT-A1 association with the galectin proteins, β-galactoside glycan binding proteins. To explore the molecular basis of the alterations of glycan structures, the highly sensitive next generation sequencing (NGS) technology, Illumina RNA-seq, was employed to analyze genes involved in the process of UT-A1 glycosylation using streptozotocin (STZ)—induced diabetic rat kidney. Differential gene expression analysis combining with quantitative PCR revealed that expression of a number of important glycosylation related genes were changed under diabetic conditions. These genes include the glycosyltransferase genes Mgat4a, the sialylation enzymes St3gal1 and St3gal4 and glycan binding protein galectin-3, -5, -8, and -9. In contrast, although highly expressed in kidney IM, the glycosyltransferase genes Mgat1, Mgat2, and fucosyltransferase Fut8, did not show any changes. Conclusions: In diabetes, not only is UT-A1 protein abundance increased but the protein's glycan structure is also significantly changed. UT-A1 protein becomes highly sialylated, fucosylated and branched. Consistently, a number of crucial glycosylation related genes are changed under diabetic conditions. The alteration of these genes may contribute to changes in the UT-A1 glycan structure and therefore modulate kidney urea transport activity and alleviate osmotic diuresis caused by glucosuria in diabetes.