Effects of Bioflavonoids from Taxus Media var. Hicksii on Superoxide Generation, Phosphorylation of Proteins and Translocation of Cytosolic Compounds to the Cell Membrane in Human Neutrophils

In present work, the effects of bioflavonoids (ginkgetin and sciadopitysin) on stimulus-induced superoxide generation, tyrosyl and serine/threonine phosphorylation of proteins in human neutrophils, and the translocation of cytosolic compounds (p47phox, p67phox and Rac) to cell membrane were studied, which were isolated from the needles of Taxus media var. Hicksii. Meanwhile, three normal flavonoids (apigenin, quercetin and isoquercetin) were involved as contrasts. The results indicated that ginkgetin and sciadopitysin were capable of concentration-dependently inhibitory effects on the superoxide generation induced by N-formyl-methionyl-leucyl-phenylalanine (fMLP), arachidonic acid (AA) and phorbol-12-myristate 13-acetate (PMA). And they also suppressed fMLP- and AA- induced tyrosyl or PMA-induced serine/threonine phosphorylation and the translocation of cytosolic compounds (p47phox, p67phox and Rac) to cell membrane, which were in parallel with the suppression of the stimulus-induced superoxide generation. The effect of these compounds on the radical-scavenging was also investigated. Ginkgetin and sciadopitysin did not show remarkable effect on DPPH radical-scavenging activity, and they didn’t display the radical-scavenging activity on superoxide anion generated by phenagine methoxysulfate (PMS)-NADH system. Apparently, ginkgetin and sciadopitysin had great performance in pharmacological value and they are worthy of in-depth study.

Transcriptional reprogramming strategies and miRNA-mediated regulation networks of Taxus media induced into callus cells from tissues

Background Taxus cells are a potential sustainable and environment-friendly source of taxol, but they have low survival ratios and slow grow rates. Despite these limitations, Taxus callus cells induced through 6 months of culture contain more taxol than their parent tissues. In this work, we utilized 6-month-old Taxus media calli to investigate their regulatory mechanisms of taxol biosynthesis by applying multiomics technologies. Our results provide insights into the adaptation strategies of T. media by transcriptional reprogramming when induced into calli from parent tissues. Results Seven out of 12 known taxol, most of flavonoid and phenylpropanoid biosynthesis genes were significantly upregulated in callus cells relative to that in the parent tissue, thus indicating that secondary metabolism is significantly strengthened. The expression of genes involved in pathways metabolizing biological materials, such as amino acids and sugars, also dramatically increased because all nutrients are supplied from the medium. The expression level of 94.1% genes involved in photosynthesis significantly decreased. These results reveal that callus cells undergo transcriptional reprogramming and transition into heterotrophs. Interestingly, common defense and immune activities, such as “plant–pathogen interaction” and salicylic acid- and jasmonic acid-signaling transduction, were repressed in calli. Thus, it’s an intelligent adaption strategy to use secondary metabolites as a cost-effective defense system. MiRNA- and degradome-sequencing results showed the involvement of a precise regulatory network in the miRNA-mediated transcriptional reprogramming of calli. MiRNAs act as direct regulators to enhance the metabolism of biological substances and repress defense activities. Given that only 17 genes of secondary metabolite biosynthesis were effectively regulated, miRNAs are likely to play intermediate roles in the biosynthesis of secondary metabolites by regulating transcriptional factors (TFs), such as ERF, WRKY, and SPL. Conclusion Our results suggest that increasing the biosynthesis of taxol and other secondary metabolites is an active regulatory measure of calli to adapt to heterotrophic culture, and this alteration mainly involved direct and indirect miRNA-induced transcriptional reprogramming. These results expand our understanding of the relationships among the metabolism of biological substances, the biosynthesis of secondary metabolites, and defense systems. They also provide a series of candidate miRNAs and transcription factors for taxol biosynthesis.