Figure 9

SNIP1 is a nuclear repressor of Smad1-regulated BMP-induced gene responses. A. Increased expression of SNIP1 inhibits BMP-induced activation of the Tlx-2 reporter gene. P19 cells were transfected with Tlx2-Luc reporter, BMP type I receptor ALK2, the BMP type II receptor BMPRII and different amount of SNIP1, as indicated. ΔN-SNIP: a.a. 142–396, defective in binding to CBP/p300 [25]. BMP7 was added at a final concentration of 250 ng/ml. The arbitrary units of the luciferase activities of each group are presented with error bars. The assays were carried out in triplicate, and similar data were reproduced three times. B. Increased expression of SNIP1 or lactacystin treatment both can inhibit BMP-induced transcriptional activity of Smad1-GAL4 fusion protein. P19 cells were transfected with GAL4-Smad1 and GAL4-Luc. Cells were treated with BMP7 (250 ng/ml) 24 hrs before lysates were made for luciferase assays. Lactacystin was added 8 hrs before cells were harvested for the assay.