Bufalin, a bufadienolide type cardiotonic steroid that is one of the major components of the toad venom-prepared traditional Chinese medicine called Ch'an Su or Senso, exhibits a cardiotonic action by inhibiting the membranous Na^+,K^+-ATPase. Bufalin also induces differentiation of leukemia cells alone or in combination with other differentiation inducers including 1@a,25-dihydroxyvitamin D"3 [1,25(OH)"2D"3]. In this study, we performed a transient cotransfection assay using a Vitamin D receptor (VDR) expression vector and a luciferase reporter and found that although bufalin did not transactivate the VDR, it effectively enhanced VDR activity induced by 1,25(OH)"2D"3. Bufalin also augmented VDR activation by bile acid ligands, such as lithocholic acid and 3-ketocholanic acid. Other cardiotonic steroids including ouabain, digitoxigenin and cinobufagin did not enhance VDR activation. Bufalin did not bind directly to VDR but did modulate the interaction of VDR and cofactors, such as steroid receptor coactivator-1 and nuclear receptor corepressor. Bufalin treatment significantly increased the expression of an endogenous VDR target gene, CYP24, in kidney- and monocyte-derived cell lines treated with 1,25(OH)"2D"3. The data indicate that bufalin-mediated cellular mechanisms such as interaction with Na^+,K^+-ATPase may affect VDR transcriptional activity. Bufalin may be a useful tool in the investigation of VDR regulation by membrane-originating cellular signals and of pathophysiological mechanisms linking VDR to cardiovascular dysfunction.
We investigate the near-critical dynamics of atomic density fluctuations in
The non-equilibrium self-organization transition of an optically driven quantum
Gas coupled to a single mode of a cavity. In this system cavity-mediated
Long-range interactions between atoms, tunable by the drive strength, l...
collagen, reaction with vinyl-bearing compounds of varied backbone rigidity,
i.e. 4-vinylbenzyl chloride (4VBC) and glycidyl methacrylate (GMA), was carried
out. TNBS colorimetric assay, 1H-NMR and ATR-FTIR confirmed covalent and
tunable functionalization of collagen lysines. Depending on the type...
We show that the proapoptotic effect of estrogen during osteoclastogenesis is regulated by a posttranscriptional increase in FasL production by down-regulated microRNA-21 (miR-21) biogenesis. Previously, we reported that miR-21 is highly expressed in osteoclastogenesis. We found that estrogen down-r...
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