In the present study, the function of microRNA (miR)-214 on diabetic nephropathy (DN) and diabetes of proximal tubular cells was investigated. Reverse transcription-quantitative polymerase chain reaction was used measure the expression of miR-214 in rats with DN and ELISA was performed to measure oxidative stress and ROS levels. Results indicated that miR-214 expression in the peripheral blood was significantly decreased in rats with DN. The in vitro model of DN indicated that miR-214 upregulation significantly decreased oxidative stress and reactive oxygen species (ROS) levels, but significantly increased uncoupling protein 2 (UCP2), phosphorylated (p)-Akt and p-mammalian target of rapamycin (mTOR) protein expression levels. The administration of genipin, a UCP2 inhibitor, significantly attenuated the effects of miR-214 upregulation on oxidative stress in the in vitro DN model by regulating ROS, Akt and mTOR protein expression levels. Notably, Akt inhibitor suppressed p-Akt protein expression and attenuated the effects of miR-214 upregulation on oxidative stress in the in vitro DN model. Collectively, these data suggest that miR-214 regulates diabetes through a ROS/Akt/mTOR signaling pathway by UCP2 in proximal tubular cells.

Gluconobacter oxydans is capable of rapidly incomplete oxidation of many sugars and alcohols, which means the strain has great potential for industrial purposes. Strong promoters are one of the essential factors that can improve strain performance by overexpression of specific genes. In this study, a pipeline for screening strong promoters by proteomics analysis was established. Based on the procedure, a new strong promoter designated as P B932_2000 was identified in G. oxydans WSH-003. The promoter region was characterized based on known genome sequence information using BPROM. The strength of P B932_2000 was further assessed by analysis of enhanced green fluorescent protein (egfp) expression and comparison with egfp expression by two commonly used strong promoters, P E. coli_tufB and P G. oxydans_tufB . Both quantitative real-time PCR and fluorescence intensities for egfp gene expression showed that P B932_2000 promoter is stronger than the other two. Overexpression of D-sorbitol dehydrogenase (sldh) by P B932_2000 in G. oxydans WSH-003 enhanced the titer and productivity of L-sorbose synthesis from D-sorbitol by 12.0 % and 33.3 %, respectively. These results showed that proteomics analysis is an efficient way to identify strong promoters. The isolated promoter P B932_2000 could further facilitate the metabolic engineering of G. oxydans.

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