Stultz Brian G, Jackson Donald G, Mortin Mark A, Yang Xiang, Beachy Philip A, Hursh Deborah A
Cellular and Tissue Therapy Branch, Center for Biologics Evaluation and Research, Food and Drug Administration, HFM-730, Bldg. 29B, Rm. 1E16, 8800 Rockville Pike, Bethesda, MD 20892, USA.
Dev Biol. 2006 Feb 15;290(2):482-94. doi: 10.1016/j.ydbio.2005.11.041. Epub 2006 Jan 3.
decapentaplegic (dpp) is a direct target of Ultrabithorax (Ubx) in parasegment 7 (PS7) of the embryonic visceral mesoderm. We demonstrate that extradenticle (exd) and homothorax (hth) are also required for dpp expression in this location, as well as in PS3, at the site of the developing gastric caecae. A 420 bp element from dpp contains EXD binding sites necessary for expressing a reporter gene in both these locations. Using a specificity swap, we demonstrate that EXD directly activates this element in vivo. Activation does not require Ubx, demonstrating that EXD can activate transcription independently of homeotic proteins. Restoration is restricted to the domains of endogenous dpp expression, despite ubiquitous expression of altered specificity EXD. We demonstrate that nuclear EXD is more extensively phosphorylated than the cytoplasmic form, suggesting that EXD is a target of signal transduction by protein kinases.
在胚胎内脏中胚层的第7副节(PS7)中,驼背蛋白(dpp)是超双胸蛋白(Ubx)的直接靶标。我们证明,额外齿状蛋白(exd)和同胸蛋白(hth)对于该位置以及发育中的胃盲囊所在的PS3中dpp的表达也是必需的。来自dpp的一个420 bp元件包含在这两个位置表达报告基因所必需的EXD结合位点。通过特异性交换,我们证明EXD在体内直接激活该元件。激活不需要Ubx,这表明EXD可以独立于同源异型蛋白激活转录。尽管改变特异性的EXD普遍表达,但恢复仅限于内源性dpp表达的结构域。我们证明,核EXD比细胞质形式的EXD磷酸化程度更高,这表明EXD是蛋白激酶信号转导的靶标。