Steroid and xenobiotic receptor

Zhou C, Assem M, Tay JC, et al. Steroid and xenobiotic receptor and vitamin D receptor crosstalk mediates CYP24 expression and drug-induced osteomalacia. J Clin Invest 2006 116(6) 1703-1712. 

Zhou C, Tabb MM, Sadatrafiei A, et al. Tocotrienols activate the steroid and xenobiotic receptor, SXR, and selectively regulate expression of its target genes. Drug Metab Dispos 2004 32(10) 1075-1082. 

Takeshita A, Koibuchi N, Oka J, et al. Bisphenol-A, an environmental estrogen, activates the human orphan nuclear receptor, steroid and xenobiotic receptor-mediated transcription. Eur J Endocrinol 2001 145 513-17. 

Zhou, C., Tabb, M. M., Nelson, E. L., Grun, E, Verma, S., Sadatrafiei, A., Lin, M., Mallick, S., Forman, B. M., Thummel, K. E., et al. (2006) Mutual repression between steroid and xenobiotic receptor and NF-kappaB signaling pathways links xenobiotic metabolism and inflammation. J. Clin. Invest. 116, 2280-2289. 

Ichikawa, T., Horie-Inoue, K., Ikeda, K., Blumberg, B., and Inoue, S. (2006) Steroid and xenobiotic receptor SXR mediates vitamin K2-activated transcription of extracellular matrix-related genes and collagen accumulation in osteoblastic cells. J. Biol. Chem. 281, 16927-16934. 

N., Blumberg, B., and Sasano, H. (2006) Expression of the steroid and xenobiotic receptor and its possible target gene, organic anion transporting polypeptide-A, in human breast carcinoma. Cancer Res. 66, 535-542. 

Takeshita, A., Taguchi, M., Koibuchi, N., and Ozawa, Y. (2002) Putative role of the orphan nuclear receptor SXR (steroid and xenobiotic receptor) in the mechanism of CYP3A4 inhibition by xenobiotics. J. Biol. Chem. 277, 32453-32458. 

Endocrinol., 145, 513 (2001). Bisphenol-A, an Environmental Estrogen, Activates the Human Orphan Nuclear Receptor, Steroid and Xenobiotic Receptor-Mediated Transcription. 

Recent studies have suggested that MK-4, in particular, has a transcriptional regulatory function, for example, in osteosarcoma cell cultures, in which it binds to and activates the SXR steroid and xenobiotic receptor. This in turn increases mRNA levels for osteoblast markers bone alkaline phosphatase, osteoprotogerin, osteopontin, and MGP. MK-4 and its isolated geranyl-geraniol side chain was also able to suppress the synthesis of prostaglandin Ei, which is a potent bone resorption catalyst. These observations have led to speculation (i) that some of the menaqui-nones may possess some functions that are not shared by phylloquinone, and (ii) that there may be implications for cell proliferation and for cancer risk from variations in the supply of vitamin K and in its speciation. 

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