Tobacco transcription factor bHLH123 improves salt tolerance by activating NADPH oxidase NtRbohE expression.

In plants, reactive oxygen species (ROS) produced following the expression of the respiratory burst oxidase homolog (Rboh) gene are important regulators of stress responses. However, little is known about how plants acclimate to salt stress through the Rboh-derived ROS signaling pathway. Here, we showed that a 400-bp fragment of the tobacco (Nicotiana tabacum) NtRbohE promoter played a critical role in the salt response. Using yeast one-hybrid (Y1H) screens, NtbHLH123, a bHLH transcription factor, was identified as an upstream partner of the NtRbohE promoter. These interactions were confirmed by Y1H, electrophoretic mobility assay, and chromatin immunoprecipitation assays. Overexpression of NtbHLH123 resulted in greater resistance to salt stress, while NtbHLH123-silenced plants had reduced resistance to salt stress. We also found that NtbHLH123 positively regulates the expression of NtRbohE and ROS production soon after salt stress treatment. Moreover, knockout of NtRbohE in the 35S::NtbHLH123 background resulted in reduced expression of ROS-scavenging and salt stress-related genes and salt tolerance, suggesting that NtbHLH123-regulated salt tolerance is dependent on the NtbHLH123-NtRbohE signaling pathway. Our data show that NtbHLH123 is a positive regulator and acts as a molecular switch to control a Rboh-dependent mechanism in response to salt stress in plants.

Obesity related microRNA­424 is regulated by TNF­α in adipocytes.

In recent years, obesity has become a major public health concern. Obesity has been previously associated with low­grade inflammation and TNF­α induction in adipose tissue, which subsequently disrupts adipocyte metabolism. MicroRNAs (miRNAs/miRs) are important metabolic factors and their dysregulation has been associated with obesity­related metabolic syndromes. In fact, it has been directly suggested that miR­424 may be functionally associated with adipogenesis, although its exact role in this process remains unclear. The present study aimed to identify the function of miR­424 in adipogenesis. In the present study, miR­424 expression levels were analyzed during adipogenesis and the differential expression of this miRNA in the adipose tissue of obese and non­obese children was also assessed. Furthermore, the interaction between miR­424 and the adipocytokine TNF­α was determined. Finally, miR­424 target genes and downstream signaling pathways were predicted via bioinformatics and analyzed by performing a luciferase reporter assay to elucidate the functional mechanisms of miR­424 in adipogenesis of visceral adipocytes. The results revealed that the expression levels of miR­424 upregulated in the adipose tissue biopsies from obese children compared with the biopsies of non­obese children. However, in cultured adipocytes, the expression levels of miR­424 were discovered to be gradually downregulated during the adipogenesis process. TNF­α treatment significantly downregulated the expression levels of miR­424 via binding to its promoter region and reducing its transcriptional activity. Through bioinformatic prediction analysis, miR­424 target genes were analyzed, of which several were identified to be involved in signaling pathways that are known to regulate adipogenesis, such as the Wnt signaling pathway. In conclusion, the present study indicated that miR­424 was regulated by TNF­α and served an important role in adipogenesis.