Figure 5.

Developmental stage-specific inhibition of Runx2 by E2 in osteoblasts. A, MC3T3-E1 cells were treated with ethanol or E2 (10 nm) and the presence of ERα in Runx2 immunocomplexes was examined as described in Fig. 3A. B–E, MC3T3-E1 cells stably transfected with the 6XOSE2-luc Runx2 reporter were subjected to differentiation conditions and treated with ethanol (white bars) or E2 (10 nm; black bars) commencing at confluence. Levels of the indicated mRNAs were measured on d 4, 11, and 18 by quantitative RT-PCR as described in Materials and Methods. Data were corrected for the expression of ribosomal protein L10A, which itself did not significantly change during culture progression or in response to E2. RANKL was not expressed on d 4, and the low expression of OC and luciferase on this day are shown in the respective insets (mean ± sd; n = 3).