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.
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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

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Figure 2

Effect of tubular cell–derived versican V1 on fibrogenic activation of renal fibroblasts.

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Effect of tubular cell–derived versican V1 on fibrogenic activation of r...
(A) RT-PCR analysis of collagen I (Col I) in tubular cells transfected with versican V1 plasmid (n = 5). (B) Western blot analysis of Col I in tubular cells transfected with versican V1 plasmid (n = 3). (C) Western blot analysis of versican V1 in the cell extracts and culture medium of tubular cells transfected with versican V1 plasmid (n = 3). (D) BrdU cell proliferation analysis of renal fibroblasts treated with the conditioned medium of versican V1–overexpressing tubular cells (pcDNA-VCAN V1 CM) (n = 5). (E) Western blot analysis of Col I in renal fibroblasts treated with the conditioned medium of versican V1–overexpressing tubular cells (n = 3). (F) BrdU cell proliferation analysis of renal fibroblasts treated with purified versican V1, V0, or V3 (n = 5). (G) Western blot analysis of Col I in renal fibroblasts treated with purified versican V1, V0, or V3 (n = 3). (H) BrdU cell proliferation analysis of renal fibroblasts treated with versican V1, si-CD44, si-PSGL1, si-EGFR, or si-ITGB1 (n = 5). (I) Western blot analysis of Col I in renal fibroblasts treated with versican V1, si-CD44, si-PSGL1, si-EGFR, or si-ITGB1 (n = 3). (J) IP analysis of the binding between versican and CD44 in renal fibroblasts treated with versican V1 and CD44 mAb (n = 3). (K) Western blot analysis of p-Smad3 in renal fibroblasts treated with versican V1 and CD44 mAb (n = 3). (L) BrdU cell proliferation analysis of renal fibroblasts treated with versican V1 and CD44 mAb (n = 5). (M) Western blot analysis of Col I in renal fibroblasts treated with versican V1 and CD44 mAb (n = 3). (N) BrdU cell proliferation analysis of renal fibroblasts treated with versican V1 and si-Smad3 (n = 5). (O) Western blot analysis of Col I in renal fibroblasts treated with versican V1 and si-Smad3 (n = 3). For statistical analysis, 1-way ANOVA with Tukey’s post hoc test was used for A, D, F, H, L, and N. *P < 0.05 compared with control; #P < 0.05 compared with renal fibroblasts treated with versican V1.