Correlation between FUT4 expression and its promoter methylation in HaCaT cells.

The expression level of fucosyltransferase Ⅳ (FUT4) is low in normal cells. The mechanism underlying regulation of FUT4 expression in normal cells remains elusive. In this study, Western blot, immunofluorescence and real-time PCR were used to analyze FUT4 expression in the immortalized human keratinocytes cells HaCaT. Methylated-specific PCR was used to investigate methylation status of FUT4 promoter. The results showed that the FUT4 expression level was significantly lower in HaCaT cells than squamous carcinoma cells A431 and SCC12. FUT4 mRNA expression was increased in HaCaT cells treated by 5-aza-dC (5 µmol/L), an inhibitor of DNA methyltransferase. Furthermore, using the primers to amplify the methylated fragment yielded PCR products and no products were yielded by the primers to amplify the unmethylated fragment in HaCaT cells. Unmethylated PCR products were obtained in HaCaT cells treated by 5-aza-dC, while methylated PCR products were not detected. These results suggest that the lower expression of FUT4 in HaCaT cells may be correlated with the methylation of CpG island in FUT4 promoter.

Constitutive and salt-inducible expression of SlBADH gene in transgenic tomato (Solanum lycopersicum L. cv. Micro-Tom) enhances salt tolerance.

To improve the stress tolerance of crops, many genes, including transcription factors, have been expressed in transgenic plants using either constitutive or stress-inducible promoters. However, transgenic plants that show strong constitutive expression of transcription factors often suffer from many undesirable phenotypes, such as stunted growth and reduced yield. In the present study, the betaine aldehyde dehydrogenase (BADH) gene, cloned from Suaeda liaotungensis and, controlled by the Cauliflower mosaic virus (CaMV) 35S promoter or stress-inducible promoter of BADH (P5: -300 to +62 bp), was transformed into tomato (Solanum lycopersicum). The transformants with single copy of SlBADH were determined by real time PCR. Expression of SlBADH in the P5:BADH transgenic plants exhibited salt induced and was higher than that in CaMV35S:BADH under salt stress. The SlBADH enhanced salt tolerance of P5:BADH and CaMV35S:BADH transformants. And SlBADH in P5:BADH plants did not affect the growth of transformants. Consequently, we conclude that the P5 promoter can drive increased expression of SlBADH in transgenic tomato under salt stress and increase salt tolerance without affecting plant growth.