Screening Of Chinese Herbs Targeting At RXRα

Retinoid X receptor (RXR) is a member of the family of non-steroid hormonereceptors of the nuclear receptor superfamily. RXRs are ligand-activated transcriptionfactors that regulate many aspects of metazoan life. They now consist of threeisotypes, α, β and γ. RXRs play critical roles in a wide range of developmentalprocesses, from embryo implantation to organogenesis, as well as in the regulation ofadult physiology and metabolic processes. RXR is a suitable therapeutic target andnow has received more and more attention.In this thesis, MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide] assay, reporter gene assay, and ligand-binding assay were used to study theinhibition of the growth of human tumor cells by Chinese herbs, and their effect ontransactivity of RXRα and the competitive ligand binding to RXRα protein. 1098Chinese herbs had been screened and 10 groups which contain 19 Chinese herbs werefound active. They could eminently inhibit the growth of human tumor cells, inhibitthe transactivity of RXRα, and inhibit the competitive ligand binding to RXRα protein.All these Chinese herbs are now under the operation of separating and purification, soas to carry out further pharmic studies.Chemokine receptors, which belong to the G protein-coupled receptor (GPCR)family, participate in a variety of physiological functions and become a kind ofimportant drug targets. In this thesis, stable cell line of CHO/CXCR1 which stablyexpressed chemokine receptor CXCR1 was set up. The optimization of [35S]GTPγSbinding assay on CHO/CXCR1 was studied and it was found that the addition of 10μg/ml of Saponin to the assay system could facilitate the activation of the receptor andthe specific binding of [35S]GTPγS to receptor G-protein complexes, enlarge thestimulation ratio. But some other detergents had no such effect. It was also found infurther study that the effect of Saponin upon the activation of various chemokinereceptors was different.