These findings suggest an important role for miR-135a in renal fibrosis and inhibition of miR-135a might be an effective therapy for diabetic nephropathy.

No abstract

Aim: To investigate the effects of the wingless-related MMTV integration site 3A (Wnt3a) signaling on the proliferation, migration, and the myogenic and adipogenic differentiation of rat bone marrow mesenchymal stem cells (rMSC). Methods: Primary MSC were isolated and cultured from Sprague-Dawley rats and characterized by flow cytometry. Mouse L cells were transfected with Wnt3a cDNA, and conditioned media containing active Wnt3a proteins were prepared. Cell proliferation was evaluated by cell count and 5-bromodeoxyuridine incorporation assay. The migration of rMSC was performed by using a transwell migration and wound healing assay. The myogenic and adipogenic differentiation in rMSC were examined by light microscopy, immunofluorescence, and RT-PCR at different time points after myogenic or adipogenic introduction. Results: Wnt3a signaling induced β-catenin nuclear translocation and activated the Wnt pathway in rMSC. In the presence of Wnt3a, rMSC proliferated more rapidly than the control cells, keeping their differentiation potential. Moreover, Wnt3a signaling induced 2.62% and 3.76% of rMSC-expressed desmin and myosin heavy chain after being cultured in myogenic medium. The myogenic differentiation genes, including Pax7, MyoD, Myf5, Myf4, and myogenin, were activated after Wnt3a treatment. On the other hand, Wnt3a inhibited the adipogenic differentiation in rMSC through the downregulated expression of CCAAT/enhancer-binding protein alpha (C/EBPalpha) and peroxisome proliferator-activated receptor gamma (PPARgamma). Furthermore, Wnt3a promoted the migration capacity of rMSC. Conclusion: The results indicate that Wnt3a signaling can induce myogenic differentiation in rMSC. Wnt3a signaling is also involved in the regulation of the proliferation and migration of rMSC. These results could provide a rational foundation for cell-based tissue repair in humans.

Diabetic nephropathy (DN), a vascular complication of diabetes, is the leading cause of death in patients with diabetes. The contribution of aberrantly expressed circular RNAs (circRNAs) to DN in vivo is poorly understood. Integrated comparative circRNA microarray profiling was used to examine the expression of circRNAs in diabetic kidney of db/db mice. We found that circRNA_010383 expression was markedly downregulated in diabetic kidneys, mesangial cells, and tubular epithelial cells cultured in high-glucose conditions. circRNA_010383 colocalized with miRNA-135a (miR-135a) and inhibited miR-135a function by directly binding to miR-135a. In vitro, the knockdown of circRNA_010383 promoted the accumulation of extracellular matrix (ECM) proteins and downregulated the expression of transient receptor potential cation channel, subfamily C, member 1 (TRPC1), which is a target protein of miR-135a. Furthermore, circRNA_010383 overexpression effectively inhibited the high-glucose–induced accumulation of ECM and increased TRPC1 levels in vitro. More importantly, the kidney target of circRNA_010383 overexpression inhibited proteinuria and renal fibrosis in db/db mice. Mechanistically, we identified that a loss of circRNA_010383 promoted proteinuria and renal fibrosis in DN by acting as a sponge for miR-135a. This study reveals that circRNA_010383 may be a novel therapeutic target for DN in the future.