Interferon production under the control of heterologous inducible enhancers and promoters

In a search for a useful enhancer to control expression of interferon (IFN) gene in mammalian cells, mouse IFN-beta cDNA ligated 3' downstream to the enhancer-promoter of either mouse metallothionein-I (MT-I) or Drosophila heat shock protein (HSP) was introduced into various cultured cells by calcium-phosphate precipitation method, and the level of IFN transiently produced was compared. In the case of the MT-I enhancer-promoter, low levels of IFN were produced without induction (0-21 IU/ml) and the level increased 5-50 times by heavy metals. In contrast, the basal level of expression of the HSP enhancer-promoter was very low and its expression was increased several hundred to thousand times by heat shock or arsenite. Thus the HSP enhancer-promoter appears to be a potent inducible element with very low basal level and high inducibility.     

The MIXTA-like Transcription factor MYB16 is a major regulator of cuticle formation in vegetative organs

Cuticle secreted on the surface of the epidermis of aerial organs protects plants from the external environment. We recently found that Arabidopsis MIXTA-like R2R3-MYB family members MYB16 and MYB106 regulate cuticle formation in reproductive organs and trichomes. However, the artificial miRNA (amiRNA)-mediated knockdown plants showed no clear phenotypic abnormality in vegetative tissues. In this study, we used RNA interference (RNAi) targeting MYB16 to produce plants with reduced expression of both MYB16 and MYB106. The rosette leaves of RNAi plants showed more severe permeable cuticle phenotypes than the myb106 mutants expressing the MYB16 amiRNA in the previous study. The RNAi plants also showed reduced expression of cuticle biosynthesis genes LACERATA and ECERIFERUM1. By contrast, expression of a gain-of-function MYB16 construct induced over-accumulation of waxy substances on leaves. These results suggest that MYB16 functions as a major regulator of cuticle formation in vegetative organs, in addition to its effect in reproductive organs and trichomes.