circHIPK3 Exacerbates Folic Acid-Induced Renal Tubulointerstitial Fibrosis by Sponging miR-30a

Abstract

Renal tubulointerstitial fibrosis is a common pathological feature of progressive chronic kidney disease (CKD), and current treatment has limited efficacy. The circular RNA circHIPK3 is reported to participate in the pathogenesis of various human diseases. However, the role of circHIPK3 in renal fibrosis has not been examined. In this study, we aimed to determine whether and how circHIPK3 might participate in the pathogenesis of renal fibrosis. Mice received a peritoneal injection of folic acid (250 mg/kg). Of note, 30 days later, renal fibrosis was present on periodic acid–Schiff (PAS) and Masson staining, and mRNA and protein of profibrotic genes encoding fibronectin (FN) and collagen 1 (COL1) were increased. Renal circHIPK3 was upregulated, while miR-30a was downregulated, assessed by quantitative PCR (qPCR) and fluorescence in situ hybridization (FISH). The expression of transforming growth factor beta-1 (TGF-β1) was increased by qPCR analysis, immunoblotting, and immunofluorescence. Renal circHIPK3 negatively correlated with miR-30a, and kidney miR-30a negatively correlated with TGF-β1. Target Scan and miRanda algorithms predicted three perfect binding sites between circHIPK3 and miR-30a. We found that circHIPK3, miR-30a, and TGF-β1 colocalized in the cytoplasm of human tubular epithelial cells (HK-2 cells) on FISH and immunofluorescence staining. We transfected circHIPK3 and a scrambled RNA into HK-2 cells; miR-30a was downregulated, and the profibrotic genes such as TGF-β1, FN, and COL1 were upregulated and assessed by qPCR, immunoblotting, and immunofluorescence staining. Third, the upregulation of circHIPK3, downregulation of miR-30a, and overproduction of profibrotic FN and COL1 were also observed in HK-2 cells exposed to TGF-β1. Finally, renal biopsies from patients with chronic tubulointerstitial nephritis manifested similar expression patterns of circHIPK3, miR-30a, and profibrotic proteins, such as TGF-β1, FN, and COL1 as observed in the experimental model. A feed-forward cycle was observed among circHIPK3, miR-30a, and TGF-β1. Our results suggest that circHIPK3 may contribute to progressive renal fibrosis by sponging miR-30a. circHIPK3 may be a novel therapeutic target for slowing CKD progression.

circMTND5 Participates in Renal Mitochondrial Injury and Fibrosis by Sponging MIR6812 in Lupus Nephritis

“…circRNA_010383 sponging miR-135a, circHIPK3 sponging miR-185, circEIF4G2 sponging miR-218, circ_0000491 sponging miR-455-3p, circLRP6 sponging miR-205, and circ_15698 sponging miR-185 contribute to cell death, extracellular matrix production, or renal fibrosis in diabetic nephropathy [ 32 – 37 ]. Our group reported that circHIPK3 aggravate renal tubulointerstitial fibrosis by regulating miR-30a [ 38 ]. In human kidney diseases, circRNAs have been profiled in exosomes isolated from serum and urine samples from patients with idiopathic membranous nephropathy [ 39 ].…”

IL-18 deficiency ameliorates the progression from AKI to CKD

“…hTGF-β is a well-accepted as a stimulator to induce kidney tubular cells damage for investigating mechanisms in vitro study [ 27 ]. It is reported that cell death and fibrosis are increased in hTGF-β1-treated kidney tubular cells [ 28 , 29 ]. We founded that IL-18 mRNA was gradually upregulated in HK-2 cells from 12 to 48 h after hTGF-β stimulation analyzed by qPCR (Fig.…”

Automated Computer-Assisted Image Analysis for the Fast Quantification of Kidney Fibrosis

“…Although there are better approaches such as artificial intelligence [ 17 ] and machine learning [ 18 ] that use convolutional neural networks trained to learn how to interpret the results of a given sample, reproducing the pathologist visual assessment [ 19 , 20 , 21 , 22 ], there are also more straightforward approaches such as image processing software. One of the most used is the free software ImageJ [ 13 , 23 , 24 , 25 , 26 , 27 ] and, more effectively, automated software such as CellProfiler™.…”