C3a and suPAR drive versican V1 expression in tubular cells of focal segmental glomerulosclerosis
Runhong Han, … , Zhihong Liu, Hao Bao
Runhong Han, … , Zhihong Liu, Hao Bao
Published April 4, 2019
Citation Information: JCI Insight. 2019;4(7):e122912. https://doi.org/10.1172/jci.insight.122912.
View: Text | PDF | Corrigendum
Research Article Nephrology

C3a and suPAR drive versican V1 expression in tubular cells of focal segmental glomerulosclerosis

Abstract

Chronic tubulointerstitial injury impacts the prognosis of focal segmental glomerulosclerosis (FSGS). We found that the level of versican V1 was increased in tubular cells of FSGS patients. Tubular cell–derived versican V1 induced proliferation and collagen synthesis by activating the CD44/Smad3 pathway in fibroblasts. Both urine C3a and suPAR were increased and bound to the tubular cells in FSGS patients. C3a promoted the transcription of versican by activating the AKT/β-catenin pathway. C3aR knockout decreased the expression of versican in Adriamycin-treated (ADR-treated) mice. On the other hand, suPAR bound to integrin β6 and activated Rac1, which bound to SRp40 at the 5′ end of exon 7 in versican pre-mRNA. This binding inhibited the 3′-end splicing of intron 6 and the base-pair interactions between intron 6 and intron 8, leading to the formation of versican V1. Cotreatment with ADR and suPAR specifically increased the level of versican V1 in tubulointerstitial tissues and caused more obvious interstitial fibrosis in mice than treatment with only ADR. Altogether, our results show that C3a and suPAR drive versican V1 expression in tubular cells by promoting transcription and splicing, respectively, and the increases in tubular cell–derived versican V1 induce interstitial fibrosis by activating fibroblasts in FSGS.

Authors

Runhong Han, Shuai Hu, Weisong Qin, Jinsong Shi, Qin Hou, Xia Wang, Xiaodong Xu, Minchao Zhang, Caihong Zeng, Zhihong Liu, Hao Bao

×

Figure 8

Rac1 induces the skipping of versican exon 7 by interacting with SRp40 in tubular cells.

Options: View larger image (or click on image) Download as PowerPoint
Rac1 induces the skipping of versican exon 7 by interacting with SRp40 i...
(A) Splicing factors predicted to bind to the 5′ end of versican exon 7 with the SpliceAid 2 database. (B) IP analysis of the binding between Rac1 and SRp40 in tubular cells treated with 20% PS (n = 3). (C) Immunofluorescence staining of SRp40 (green), Rac1 (red), and DAPI (blue) in tubular cells treated with 20% PS (n = 3). Scale bars: 20 μm. (D) RIP analysis of the binding of SRp40 and Rac1 to the 5′ end of versican exon 7 in tubular cells treated with 20% PS (n = 5). (E) RIP analysis of the binding of Rac1 to the 5′ end of versican exon 7 in tubular cells treated with 20% PS and si-SRp40 (n = 3). (F) RIP analysis of the binding of SRp40 to the 5′ end of versican exon 7 in tubular cells treated with 20% PS and si-Rac1 (n = 3). (G) Rac1 activity in tubular cells treated with 20% PS and si-SRp40 (n = 3). (H) RIP analysis of the binding of U2AF1 to the 3′ splice site of versican intron 6 in tubular cells treated with 20% PS and pGEMT-SRp40 plasmid or suPAR-blocking antibody (n = 5). (I) PCR analysis of versican V0 and V1 in tubular cells treated with 20% PS and pGEMT-SRp40 plasmid or suPAR-blocking antibody (n = 3). (J) RIP analysis of the binding of U2AF1 to the 3′ splice site of versican intron 6 in tubular cells treated with C3a and Rac1Q61L plasmid or suPAR (n = 5). (K) PCR analysis of versican V0 and V1 in tubular cells treated with C3a and Rac1Q61L plasmid or suPAR (n = 3). For statistical analysis, 1-way ANOVA with Tukey’s post hoc test was used for D–F, G, H, and J. *P < 0.05 compared with control; #P < 0.05 compared with PS- or C3a-treated cells.