Lee Hyun-Shik, Park Mae Ja, Lee Sung-Young, Hwang Yoo-Seok, Lee Hyosang, Roh Dong-Hyun, Kim Jong-Il, Park Jae-Bong, Lee Jae-Yong, Kung Hsiang-fu, Kim Jaebong
Department of Biochemistry, College of Medicine, Hallym University, ChunCheon, Kangwon-Do, Republic of Korea.
Biochem Biophys Res Commun. 2002 Nov 15;298(5):815-23. doi: 10.1016/s0006-291x(02)02570-6.
Xvent homeobox proteins are induced by BMP-4 signaling and have been known to mediate many BMP-4 activities as key downstream transcriptional factors. In order to investigate the regulatory mode of Xvent transcription, we isolated genomic DNA of the Xbr-1a/Xvent-2 containing the promoter region responsive to BMP-4 signaling. The cis-acting elements located within the Xbr-1a/Xvent-2 promoter and the regulation modes by BMP-4 signaling were analyzed by serial deletion and site-directed mutagenesis experiments. The upstream -235bp of the promoter retained the full transcriptional activity and BMP-4-response when compared with the longest promoter construct. Further analysis indicated that two separated 15bp regions contained a strong positive element and BMP-4-response element. Site-directed mutagenesis of those regions suggests that those two regions cooperate for the promoter activity and BMP-4-response. Moreover, we found that the transcription factors, Oaz and PEBP2alphaA, were able to elicit additive effects with BMP-4 signaling on Xbr-1a/Xvent-2 reporter activities. These results indicate that transcriptional regulation of the Xbr-1a/Xvent-2 gene occurs in a complex mode through the cooperation of various transcription factors.
Xvent 同源框蛋白由骨形态发生蛋白-4（BMP-4）信号诱导产生，并且作为关键的下游转录因子，已知其介导许多 BMP-4 的活性。为了研究 Xvent 转录的调控模式，我们分离了包含对 BMP-4 信号有反应的启动子区域的 Xbr-1a/Xvent-2 的基因组 DNA。通过连续缺失和定点诱变实验分析了位于 Xbr-1a/Xvent-2 启动子内的顺式作用元件以及 BMP-4 信号的调控模式。与最长的启动子构建体相比，启动子上游-235bp 保留了完整的转录活性和 BMP-4 反应性。进一步分析表明，两个分开的 15bp 区域包含一个强阳性元件和 BMP-4 反应元件。对这些区域的定点诱变表明，这两个区域协同发挥启动子活性和 BMP-4 反应性。此外，我们发现转录因子 Oaz 和 PEBP2alphaA 能够与 BMP-4 信号对 Xbr-1a/Xvent-2 报告基因活性产生累加效应。这些结果表明，Xbr-1a/Xvent-2 基因的转录调控通过多种转录因子的协同作用以复杂的模式发生。
