Editorial Feature: Meet the PCP Editor-Kenichi Tsuda.
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Editorial↗
Biomedical subjects
Kenichi Tsuda
Publications and source records attributed to Kenichi Tsuda.
A simple and extremely sensitive system for detecting estrogenic activity using transgenic Arabidopsis thaliana.
Numerous physiological processes are regulated by endocrine systems in animals. Endocrine-disrupting chemicals (EDCs) can affect physiological processes of organisms by binding to hormone receptors. Therefore, it is necessary to develop methods for detecting EDCs and removing them from the environment. We have developed a simple and low-cost reporter gene assay system for the comprehensive analysis of estrogenic activity using transgenic Arabidopsis thaliana. This transgenic plant constantly expresses two effector proteins: a chimeric estrogen receptor and a chimeric nuclear receptor coactivator. Estrogen-dependent interaction between the two effector proteins triggers transcriptional activation of reporter gene, beta-glucuronidase. We have demonstrated this transgenic plant's capability of detecting the existence of 17beta-estradiol at a concentration of 50 pM (13 pg/ml) in agar medium. This plant can also detect other estrogenic substances, such as diethylstilbestrol, p-n-nonylphenol, bisphenol A, and Genistein.
Animals↗
Transcriptional coactivator MBF1s from Arabidopsis predominantly localize in nucleolus.
Multiprotein bridging factor 1 (MBF1) is a transcriptional coactivator. It has been reported that MBF1 changed its subcellular localization from cytoplasm into nuclei with a transcriptional activator for activation of a target gene expression in animals. We found that Arabidopsis MBF1s (AtMBF1s) predominantly localize in nucleolus. We previously reported that plant MBF1s were rapidly induced by several stresses, whereas animal MBF1s were not induced. Therefore, we suggest that MBF1-function in plants is controlled on the level of transcriptional induction but not by nuclear translocation, dissimilar from the case of MBF1s from animals.
Arabidopsis↗
Structure and expression analysis of three subtypes of Arabidopsis MBF1 genes.
Multiprotein bridging factor 1 (MBF1) is a transcriptional co-activator that mediates transcriptional activation by bridging between an activator and a TATA-box binding protein (TBP). Recently, we have reported that three Arabidopsis MBF1s play roles as transcriptional co-activators. This study shows that AtMBF1c is totally different from the other two in its structure and expression pattern, and that MBF1c genes also occur in other plant species, including monocots. We performed histochemical analysis of these genes using beta-glucuronidase (GUS) assays to characterize the expression profile of each AtMBF1 gene extensively. In pAtMBF1a Colon, two colons GUS transformants, GUS staining was observed only in anthers and seeds, whereas strong GUS activity in pAtMBF1b Colon, two colons GUS transformants was detected in leaf veins, stems, anthers, and seeds. In mature pAtMBF1c Colon, two colons GUS transformants, GUS staining was observed in almost all tissues. It is noteworthy that intense GUS staining was observed in anthers of all transformants. We also found that AtMBF1c expression was up-regulated upon diverse stress treatments including exposure to heat, hydrogen peroxide, dehydration, and high concentrations of salt. These findings suggest that AtMBF1c may be involved in stress response pathway.
Amino Acid Sequence↗
Three Arabidopsis MBF1 homologs with distinct expression profiles play roles as transcriptional co-activators.
Multiprotein bridging factor 1 (MBF1) is known to be a transcriptional co-activator that mediates transcriptional activation by bridging between an activator and a TATA-box binding protein (TBP). We demonstrated that expression of every three MBF1 from Arabidopsis partially rescues the yeast mbf1 mutant phenotype, indicating that all of them function as co-activators for GCN4-dependent transcriptional activation. We also report that each of their subtypes shows distinct tissue-specific expression patterns and responses to phytohormones. These observations suggest that even though they share a similar biochemical function, each MBF1 has distinct roles in various tissues and conditions.
Arabidopsis↗