Background The primary pigments in flowers are anthocyanins, the biosynthesis of which is mainly regulated by R2R3-MYBs. Muscari armeniacum is an ornamental garden plant with deep cobalt blue flowers containing delphinidin-based anthocyanins. An anthocyanin-related R2R3-MYB MaAN2 has previously been identified in M. armeniacum flowers; here, we also characterized a novel R2R3-MYB MaMybA, to determine its function and highlight similarities and differences between MaMybA and MaAN2. Results In this study, a novel anthocyanin-related R2R3-MYB gene was isolated from M. armeniacum flowers and functionally identified. A sequence alignment showed that MaMybA contained motifs typically conserved with MaAN2 and its orthologs. However, the shared identity of the entire amino acid sequence between MaMybA and MaAN2 was 43.5%. Phylogenetic analysis showed that they were both clustered into the AN2 subgroup of the R2R3-MYB family, but not in the same branch. We also identified a IIIf bHLH protein, MabHLH1, in M. armeniacum flowers. A bimolecular fluorescence complementation assay showed that MabHLH1 interacted with MaMybA or MaAN2 in vivo; a dual luciferase assay indicated that MaMybA alone or in interaction with MabHLH1 could regulate the expression of MaDFR and AtDFR, but MaAN2 required MabHLH1 to do so. When overexpressing MaMybA in Nicotiana tabacum ‘NC89’, the leaves, petals, anthers, and calyx of transgenic tobacco showed intense and magenta anthocyanin pigments, whereas those of OE-MaAN2 plants had lighter pigmentation. However, the ovary wall and seed skin of OE-MaMybA tobacco were barely pigmented, while those of OE-MaAN2 tobacco were reddish-purple. Moreover, overexpressing MaMybA in tobacco obviously improved anthocyanin pigmentation, compared to the OE-MaAN2 and control plants, by largely upregulating anthocyanin biosynthetic and endogenous bHLH genes. Notably, the increased transcription of NtF3′5′H in OE-MaMybA tobacco might lead to additional accumulation of delphinidin 3-rutinoside, which was barely detected in OE-MaAN2 and control plants. We concluded that the high concentration of anthocyanin and the newly produced Dp3R caused the darker color of OE-MaMybA compared to OE-MaAN2 tobacco. Conclusion The newly identified R2R3-MYB transcription factor MaMybA functions in anthocyanin biosynthesis, but has some differences from MaAN2; MaMybA could also be useful in modifying flower color in ornamental plants.

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Overcoming chemorestistance to 5-fluorouracil (5-FU) could offer a new treatment option for highly malignant colon cancer. In our study, differential microRNA expression profiling revealed that miR-214 is downregulated in 5-FU-resistant colon cancer cells compared to normal cells. In vitro, miR-214 could sensitize non-resistant colon cancer cells and 5-FU-resistant colon cancer cellsto 5-FU. Functionally, miR-214 inhibited cell clone formation and cell growth and enhanced 5-FU-inducing cell apoptosis and caspase-3 levels. MiR-214 targeted heat shock protein 27 (Hsp27), as confirmed via dual luciferase reporter assays and western blots. Hsp27 also sensitized HT-29 and LoVo to 5-FU by enhancing cell apoptosis. Overexpression of Hsp27 could block miR-214 with an effect on the sensitivity of colon cancer cells to 5-FU. In conclusion, miR-214 sensitizes colon cancer cells to 5-FU by targeting Hsp27, indicating a significant role for this miRNA in colon cancer chemotherapy.Electronic supplementary materialThe online version of this article (10.1186/s11658-019-0143-3) contains supplementary material, which is available to authorized users.

Slit homolog 2 (Slit2) is distributed in various tissues and participates in numerous cellular processes; however, the role of Slit2 in the regulation of angiogenesis remains controversial, since it has previously been reported to exert proangiogenic and antiangiogenic activities. The present study aimed to investigate the effects of Slit2 on vascular endothelial cell proliferation and migration in vitro, and to reveal the possible underlying signaling pathway. Aortic endothelial cells were isolated from Sprague Dawley rats and cultured. Cell proliferation assay, cell migration assay, immunocytochemistry and small interfering RNA transfection were subsequently performed. The results demonstrated that exogenous Slit2 administration markedly suppressed TNF-α-induced endothelial cell proliferation and migration in vitro. In addition, TNF-α application upregulated the protein expression levels of vascular endothelial growth factor (VEGF) and Notch in RAECs, whereas Slit2 administration downregulated VEGF and Notch expression in RAECs cultured in TNF-α conditioned medium. Further studies indicated that knockdown of VEGF suppressed the effects of TNF-α on the induction of RAEC proliferation and migration. VEGF knockdown-induced inhibition of RAEC proliferation and migration in TNF-α conditioned medium was also achieved without Slit2 administration. Furthermore, VEGF knockdown markedly decreased Notch1 and Notch2 expression. These results indicated that Slit2 suppresses TNF-α-induced vascular endothelial cell proliferation and migration in vitro by inhibiting the VEGF-Notch signaling pathway. Therefore, Slit2 may inhibit the proliferation and migration of endothelial cells during vascular development.