1,25-Dihydroxyvitamin D(3) Inhibits Podocyte uPAR Expression and Reduces Proteinuria

Jianchao Ma,Yun Yang,Lixia Xu,Chunping Yu,Shuangxin Liu,Bin Zhang,Shaoting Xie,Yujun Deng,Wei Shi,Juan Ma,Li Zhang,Wenjian Wang,Ruizhao Li,Maria Pia Rastaldi

doi:10.1371/journal.pone.0064912

Jianchao Ma, Yun Yang + Show 12 more

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https://doi.org/10.1371/journal.pone.0064912

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Abstract

BackgroundAccumulating studies have demonstrated that 1,25-Dihydroxyvitamin D(3) (1,25(OH)2D3) reduces proteinuria and protects podocytes from injury. Recently, urokinase receptor (uPAR) and its soluble form have been shown to cause podocyte injury and focal segmental glomerulosclerosis (FSGS). Here, our findings showed that 1,25(OH)2D3 did inhibit podocyte uPAR expression and attenuate proteinuria and podocyte injury.Methodology/Principal FindingsIn this study, the antiproteinuric effect of 1,25(OH)2D3 was examined in the lipopolysaccharide mice model of transient proteinuria (LPS mice) and in the 5/6 nephrectomy rat FSGS model(NTX rats). uPAR protein expression were tested by flow cytometry, immune cytochemistry and western blot analysis, and uPAR mRNA expression by real-time quantitative PCR in cultured podocytes and kidney glomeruli isolated from mice and rats. Podocyte motility was observed by transwell migration assay and wound healing assay. Podocyte foot processes effacement was identified by transmission electron microscopy. We found that 1,25(OH)2D3 inhibited podocyte uPAR mRNA and protein synthesis in LPS-treated podocytes, LPS mice and NTX rats, along with 1,25(OH)2D3 reducing proteinuria in NTX rats and LPS mice.1,25(OH)2D3 reduced glomerulosclerosis in NTX rats and alleviated podocyte foot processes effacement in LPS mice. Transwell migration assay and wound healing assay showed that LPS-induced podocyte motility, irrespective of random or directed motility, were substantially reduced by 1,25(OH)2D3.Conclusions/SignificanceOur results demonstrated that 1,25(OH)2D3 inhibited podocyte uPAR expression in vitro and in vivo, which may be an unanticipated off target effect of 1,25(OH)2D3 and explain its antiproteinuric effect in the 5/6 nephrectomy rat FSGS model and the LPS mouse model of transient proteinuria.

Highlights

Proteinuria is a key feature of kidney glomerular dysfunction, and it is a risk factor for both renal and extrarenal diseases [1]
Conclusions/Significance: Our results demonstrated that 1,25(OH)2D3 inhibited podocyte uPAR expression in vitro and in vivo, which may be an unanticipated off target effect of 1,25(OH)2D3 and explain its antiproteinuric effect in the 5/6 nephrectomy rat focal segmental glomerulosclerosis (FSGS) model and the LPS mouse model of transient proteinuria
Our results demonstrated that 1,25(OH)2D3 inhibited podocyte uPAR mRNA and protein synthesis in vitro and in vivo, which may be an unanticipated effect of 1,25(OH)2D3 and explain its antiproteinuric effect in the 5/6 nephrectomy rat FSGS model and the LPS mouse model of transient proteinuria

Summary

Introduction

Proteinuria is a key feature of kidney glomerular dysfunction, and it is a risk factor for both renal and extrarenal diseases [1]. The common denominator in a variety of kidney diseases is podocyte dysfunction involving proteinuria [11] Podocytes and their foot processes comprise the outer layer of the kidney ultrafiltration barrier, which is a complex cellular structure selective ultrafiltration [12,13]. In this study, we showed that 1,25(OH)2D3 inhibited the expression of podocyte uPAR, a recently confirmed pathogenic factor causing podocyte injury and proteinuria [16]. These findings that 1,25(OH)2D3 inhibited podocyte uPAR may provide a new insight into the mechanisms underlying its well-known antiproteinuric effect

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