Table 2.
Differential activation of GAL4-RARs and GAL4-RXRs by 9-cis-4-oxo-RA
| Retinoid | EC50, nM
|
|||||
|---|---|---|---|---|---|---|
| GAL4-RARα | GAL4-RARβ | GAL4-RARγ | GAL4-RXRα | GAL4-RXRβ | GAL4-RXRγ | |
| RA | 5.9 | 1.0 | 1.1 | ≥800 | ≥1,000 | ≥1,000 |
| 4-oxo-RA | 21.9 | 5.4 | 11.8 | ≥800 | ≥1,000 | ≥1,000 |
| 9-cis-RA | 26.3 | 5.4 | 14.2 | 10.4 | 80.17 | 67.5 |
| 9-cis-4-oxo-RA | 72.8 | 33.6 | 44.9 | ≥800 | ≥1,000 | ≥800 |
GAL4-receptor chimeras were cotransfected with GAL4-luc reporter and SV2lacZ in COS-1 cells. EC50 values are shown and represent concentrations required to produce 50% of the maximal response induced by RA (GAL4-RARs) or 9-cis-RA (GAL4-RXRs). At a high concentration (10−6 M), RA, 4-oxo-RA and 9-cis-4-oxo-RA caused partial activation of GAL4-RXRs (expressed as % relative to maximal activation induced by 9-cis-RA): GAL4-RARα, 60.2, 64.7, 59.7; GAL4-RXRβ, 50.4, 19.6, 58.9; GAL4-RXRγ, 48.9, 33.9, 65.3, respectively. Data are means of at least three experiments. SD was <25%.