Abstract
Objective To investigate the role of microRNA-130b in 1,25(OH)2D3 mediated improvement of renal fibrosis via transforming growth factor-beta 1 in a rat model of diabetic nephropathy (DN). Methods DN was induced in 30 rats by intraperitoneal injection of streptozotocin. These rats were randomly allocated to the DN group, TGF-β1 overexpression group (in situ injection of TGF-β1 lentivirus to kidney tissues), and TGF-β1 siRNA group (in situ injection of TGF-β1 siRNA lentivirus to kidney tissues). Rats with different expression levels of TGF-β1 were administered 1,25(OH)2D3 (0.03 μg/kg/d) or peanut oil as control. DN rats were treated only with peanut oil. All rats were randomly divided into five groups (n = 6 per group): TGF-β1 overexpression + oil, TGF-β1 overexpression + 1,25(OH)2D3, TGF-β1 siRNA + oil, TGF-β1 siRNA + 1,25(OH)2D3, and DN + oil groups. After 37 days, kidney samples were collected and the expression of TGF-β1 and miR-130b was determined by real-time PCR, western blotting, and immunohistochemistry. Hematoxylin and eosin staining and Masson staining were used to evaluate kidney morphological and fibrogenic changes. Differences were determined using ANOVA and Student's t-test. Results RT-PCR, western blotting, and immunohistochemistry revealed that interference of TGF-β1 significantly decreased mRNA and protein levels of TGF-β1 in renal tissues of DN rats compared to those in renal tissues of rats overexpressing TGF-β1 (p < 0.05). Histological analysis showed that upregulated TGF-β1 led to disorganized kidney structure and severe kidney fibrosis. The expression of miR-130b was significantly lowered upon lentivirus-mediated overexpression of TGF-β1 than upon downregulation of TGF-β1 (p < 0.05). Treatment with 1,25(OH)2D3 led to a significant reduction of TGF-β1 at the mRNA and protein levels (both p < 0.05), improvement of renal structure and fibrosis, and an increase in miR-130b expression (p < 0.05). Conclusion TGF-β1 can decrease the expression of miR-130b in kidney tissues of DN rats. Moreover, miR-130b may be involved in the protective effect of 1,25(OH)2D3 on renal fibrosis via TGF-β1.
Highlights
Diabetic nephropathy (DN) is the most common complication of diabetes and the main cause of end-stage renal failure disease
It has been found that TGF-β has a biphasic induction process on miR-192 expression in mouse mesangial cells in which AKT-activated P300-induced transcription factors Ets-1 and histone H3 acetylation leads to the sustained expression of Smad [11]. e expression level of miRNA-22 is significantly increased during the pathogenesis of diabetic nephropathy, and miRNA-22 promotes the expression of type IV collagen (Col IV) and inhibits the autophagy of renal tubular epithelial cells by targeting phosphatase and tensin homolog (PTEN), inducing tubulointerstitial fibrosis and promoting the development of diabetic nephropathy [12]
It has been shown that miR130b plays a protective role in the fibrosis of diabetic nephropathy by mediating the cascade amplification induced by TGF-β1 stimulation
Summary
To investigate the role of microRNA-130b in 1,25(OH)2D3 mediated improvement of renal fibrosis via transforming growth factor-beta 1 in a rat model of diabetic nephropathy (DN). Rats with different expression levels of TGF-β1 were administered 1,25(OH)2D3 (0.03 μg/kg/d) or peanut oil as control. After 37 days, kidney samples were collected and the expression of TGF-β1 and miR-130b was determined by real-time PCR, western blotting, and immunohistochemistry. RT-PCR, western blotting, and immunohistochemistry revealed that interference of TGF-β1 significantly decreased mRNA and protein levels of TGF-β1 in renal tissues of DN rats compared to those in renal tissues of rats overexpressing TGF-β1 (p < 0.05). Treatment with 1,25(OH)2D3 led to a significant reduction of TGF-β1 at the mRNA and protein levels (both p < 0.05), improvement of renal structure and fibrosis, and an increase in miR-130b expression (p < 0.05). TGF-β1 can decrease the expression of miR130b in kidney tissues of DN rats. MiR-130b may be involved in the protective effect of 1,25(OH)2D3 on renal fibrosis via TGF-β1
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