Most chronic kidney injuries inevitably progress to irreversible renal fibrosis. Tubular epithelial-to-mesenchymal transition (EMT) is recognized to play pivotal roles in the process of renal fibrosis. However, a comprehensive understanding of the pathogenesis of renal scar formation and progression remains an urgent task for renal researchers. The endogenously produced microRNAs (miRNAs), proved to play important roles in gene regulation, probably regulate most genes involved in EMT. In this study, we applied microarray analysis to investigate the expression profiles of miRNA in murine interstitial fibrotic kidneys induced by unilateral ureteral obstruction (UUO). It was found that miR-200a and miR-141, two members of the miR-200 family, were downregulated at the early phase of UUO. In TGF-β1-induced tubular EMT in vitro, it was also found that the members of the miR-200 family were downregulated in a Smad signaling-dependent manner. It was demonstrated that the miR-200 family was responsible for protecting tubular epithelial cells from mesenchymal transition by target suppression of zinc finger E-box-binding homeobox (ZEB) 1 and ZEB2, which are E-cadherin transcriptional repressors. The results suggest that downregulation of the miR-200 family initiates the dedifferentiation of renal tubules and progression of renal fibrosis, which might provide important targets for novel therapeutic strategies.

Hox gene clusters play an important role during cardiac septation to valve formation in different species, and the miR-196a-HOXB8-Sonic hedgehog signaling pathway is of particular interest. Recently, we found that a genetic variant of rs11614913 in the miR-196a2 sequence could alter mature miR-196a expression and target mRNA binding; this observation led us to hypothesize that rs11614913 might influence susceptibility to sporadic congenital heart disease (CHD). We conducted a three-stage case-control study of CHD in Chinese to test our hypothesis by genotyping miR-196a2 rs11614913 and three other pre-miRNA SNPs (miR-146a rs2910164, miR-149 rs2292832, and miR-499 rs3746444) in 1,324 CHD cases and 1,783 non-CHD controls. We found that rs11614913 CC was associated with a significantly increased risk of CHD in all three stages combined (P=6.81 x 10(-6)). In a genotype-phenotype correlation analysis using 29 cardiac tissue samples of CHD, rs11614913 CC was associated with significantly increased mature miR-196a expression (P=0.001). In vitro binding assays further revealed that the rs11614913 variant affects HOXB8 binding to mature miR-196a. This is the first study to indicate that miR-196a2 rs11614913 plays a role in sporadic CHD susceptibility.

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Development of fluorescent probes for on-site sensing and long-term tracking of specific biomarkers is particularly desirable for the early detection of diseases. However, available small-molecule probes tend to facilely diffuse across the cell membrane or remain at the activation site but always suffer from the aggregation-caused quenching (ACQ) effect. Here we report an enzyme-activatable aggregationinduced emission (AIE) probe QM-bgal, which is composed of a hydrophilic b-galactosidase (b-gal)triggered galactose moiety and a hydrophobic AIE-active fluorophore QM-OH. The probe is virtually non-emissive in aqueous media, but when activated by b-gal, specific enzymatic turnover would liberate hydrophobic AIE luminogen (AIEgen) QM-OH, and then highly fluorescent nanoaggregates are in situ generated as a result of the AIE process, allowing for on-site sensing of endogenous b-gal activity in living cells. Notably, taking advantage of the improved intracellular retention of nanoaggregates, we further exemplify QM-bgal for long-term ($12 h) visualization of b-gal-overexpressing ovarian cancer cells with high fidelity, which is essential for biomedicine and diagnostics. Thus, this enzyme-activatable AIE probe not only is a potent tool for elucidating the roles of b-gal in biological systems, but also offers an enzyme-regulated liberation strategy to exploit multifunctional probes for preclinical applications.Scheme 1 Schematic illustration of an enzyme-regulated liberation strategy for on-site sensing and long-term tracking.Scheme 2 Enzyme-activatable probes for b-gal activity sensing.This journal is

Mitochondria dysfunction has been reported in various kidney diseases but how it leads to kidney fibrosis and how this is regulated is unknown. Here we found that mitochondrial uncoupling protein 2 (UCP2) was induced in kidney tubular epithelial cells after unilateral ureteral obstruction in mice and that mice with ablated UCP2 resisted obstruction-induced kidney fibrosis. We tested this association further in cultured NRK-52E cells and found that TGF-β1 remarkably induced UCP2 expression. Knockdown of UCP2 largely abolished the effect of TGF-β1, whereas overexpression of UCP2 promoted tubular cell phenotype changes. Analysis using a UCP2 mRNA-3′-untranslated region luciferase construct showed that UCP2 mRNA is a direct target of miR-30e. MiR-30e was downregulated in tubular cells from fibrotic kidneys and TGF-β1-treated NRK-52E cells. A miR-30e mimic significantly inhibited TGF-β1-induced tubular-cell epithelial–mesenchymal transition, whereas a miR-30e inhibitor imitated TGF-β1 effects. Finally, genipin, an aglycone UCP2 inhibitor, significantly ameliorated kidney fibrosis in mice. Thus, the miR-30e/UCP2 axis has an important role in mediating TGF-β1-induced epithelial–mesenchymal transition and kidney fibrosis. Targeting this pathway may shed new light for the future of fibrotic kidney disease therapy.