LOCALIZED EXPRESSION OF SLOPPY PAIRED PROTEIN MAINTAINS THE POLARITY OF DROSOPHILA PARASEGMENTS
LOCALIZED EXPRESSION OF SLOPPY PAIRED PROTEIN MAINTAINS THE POLARITY OF DROSOPHILA PARASEGMENTS
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DOI：
10.1101/gad.8.8.899
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发表时间：
1994-04-15
影响因子：
10.5
通讯作者：
GEHRING, WJ
中科院分区：
文献类型：
--
作者：
CADIGAN, KM;GROSSNIKLAUS, U;GEHRING, WJ
在果蝇胚胎生殖带延伸过程中，细胞间通讯是维持细胞胚盘基因表达模式所必需的。例如，每个副片段（PS）中的无翅（wg）单细胞宽条纹取决于来自相邻的后部细胞的信号，这些细胞表达enrailed（en）。这个信号被认为是hedgehog（hh）基因的产物，它能拮抗patched（ptc）的活性，patched是wg表达的抑制因子。遗传证据表明hh信号是双向的，但wg转录只在en/hh条纹的前侧被去抑制。为了解释wg启动子对hh信号的不对称响应，目前的模型预测每个PS被分成能够表达wg或en的细胞，但不能同时表达两者。sloppy配对（slp）基因座包含两个转录单位，均编码含有叉头结构域（DNA结合基序）的蛋白质。slp基因功能的去除导致胚胎表现出严重的配对规则/片段极性表型。我们表明，在slp突变胚胎中，en条纹向前扩展，并且slp活性是维持wg表达的绝对要求，同时wg转录依赖于hh。slp蛋白在en阳性细胞的正前方以宽条纹的形式表达，与窄的wg条纹重叠。我们建议，凭借他们的能力，激活WG和抑制EN表达，分布的slp蛋白定义WG-主管和EN-主管组。与这一假设相一致，无处不在的表达的slp蛋白在整个PS废除en的表达，并在ptc突变胚胎，结果在一个几乎无处不在的分布的wg成绩单。除了证明slp在维持片段极性中的作用外，我们的结果还表明slp在ptc/hh信号转导通路中或与ptc/hh信号转导通路平行地调节wg转录。
During germ-band extension in the Drosophila embryo, intercellular communication is required to maintain gene expression patterns initiated at cellular blastoderm. For example, the wingless (wg) single-cell-wide stripe in each parasegment (PS) is dependent on a signal from the adjacent, posterior cells, which express engrailed (en). This signal is thought to be the hedgehog (hh) gene product, which antagonizes the activity of patched (ptc), a repressor of wg expression. Genetic evidence indicates that the hh signal is bidirectional, but wg transcription is only derepressed on the anterior side of the en/hh stripes. To explain the asymmetric response of the wg promoter to the hh signal, current models predict that each PS is divided into cells that are competent to express either wg or en, but not both. The sloppy paired (slp) locus contains two transcription units, both encoding proteins containing a forkhead domain, a DNA-binding motif. Removal of slp gene function causes embryos to exhibit a severe pair-rule/segment polarity phenotype. We show that the en stripes expand anteriorly in slp mutant embryos and that slp activity is an absolute requirement for maintenance of wg expression at the same time that wg transcription is dependent on hh. The slp proteins are expressed in broad stripes just anterior of the en-positive cells, overlapping the narrow wg stripes. We propose that by virtue of their ability to activate wg and repress en expression, the distribution of the slp proteins define the wg-competent and en-competent groups. Consistent with this hypothesis, ubiquitous expression of slp protein throughout the PS abolishes en expression and, in ptc mutant embryos, results in a near ubiquitous distribution of wg transcripts. In addition to demonstrating the role of slp in maintaining segment polarity, our results suggest that slp works in, or parallel with, the ptc/hh signal transduction pathway to regulate wg transcription.