INTERCELLULAR SIGNALING IN DROSOPHILA SEGMENT FORMATION RECONSTRUCTED INVITRO
INTERCELLULAR SIGNALING IN DROSOPHILA SEGMENT FORMATION RECONSTRUCTED INVITRO
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DOI：
10.1038/363549a0
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发表时间：
1993-06-10
期刊：
影响因子：
64.8
通讯作者：
KRASNOW, MA
中科院分区：
文献类型：
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作者：
CUMBERLEDGE, S;KRASNOW, MA
遗传学研究表明，细胞间信号转导参与果蝇发育的关键步骤，但以前不可能在简化的体外系统中研究这些过程。对有爪（en）和无翅（wg）以及其他体节极性基因的分析表明，两个或多个细胞间信号传导过程可能参与了体节内模式形成1 -3。en和wg的表达在产卵后约3小时开始，在每个节原基后半部分的相邻行细胞中4 -7。在wg-胚胎和条件突变体中，其中wg功能在产卵后3至5小时的关键时期内失活，早期en表达正常开始，但随后在几小时内消失4，8-10。wg基因编码一种与小鼠Wnt-1原癌基因产物高度相似的蛋白质，一种分泌糖蛋白11，12; wg蛋白被认为充当细胞外信号，维持en表达并激活附近细胞中的其他分子和形态发生过程4，8，9，13。几条证据支持该模型，包括胚胎中wg蛋白的分泌7，14，遗传镶嵌实验15 -17和细胞谱系研究18。我们使用通过全动物细胞分选分离的纯化的胚胎细胞测试了该模型，并验证了三个关键预测：（1）当来自早期胚胎的en表达细胞在培养物中单独生长时，它们快速且选择性地丧失en表达;（2）纯化的wg表达细胞提供了防止这种丧失的局部活性信号;（3）经工程改造以表达WG的异源细胞也显示出信号传导活性，表明单独的WG蛋白或与更普遍表达的因子结合的WG蛋白是信号。
GENETIC studies show that intercellular signalling is involved in key steps in Drosophila melanogaster development, but it has not previously been possible to investigate these processes in simplified in vitro systems. Analysis of engrailed (en) and wingless (wg) and other segment polarity genes suggests that two or more intercellular signalling processes may be involved in intrasegmental patterning1-3. Expression of en and wg begins about three hours after egg laying, in adjacent rows of cells in the posterior half of each segmental primordium4-7. In wg- embryos and in conditional mutants in which wg function is inactivated during a critical period between three and five hours after egg laying, early en expression begins normally but then disappears within several hours4,8-10. The wg gene encodes a protein highly similar to the product of the mouse Wnt-1 proto-oncogene, a secreted glycoprotein11,12; wg protein is proposed to function as an extracellular signal, maintaining en expression and activating other molecular and morphogenetic processes in nearby cells4,8,9,13. Several lines of evidence support the model, including the secretion of wg protein in the embryo7,14, genetic mosaic experiments15-17 and cell lineage studies18. We tested this model using purified embryonic cells isolated by whole animal cell sorting19, and validated three key predictions: (1) when en-expressing cells from early embryos are grown alone in culture, they rapidly and selectively lose en expression; (2) purified wg-expressing cells provide a locally active signal that prevents this loss; (3) heterologous cells engineered to express wg also show signalling activity, indicating that wg protein alone, or in conjunction with more generally expressed factors, is the signal.