Domínguez M, Hafen E
Zoological Institute, University of Zürich, CH-8057 Zürich, Switzerland.
Genes Dev. 1997 Dec 1;11(23):3254-64. doi: 10.1101/gad.11.23.3254.
Patterning of the compound eye begins at the posterior edge of the eye imaginal disc and progresses anteriorly toward the disc margin. The advancing front of ommatidial differentiation is marked by the morphogenetic furrow (MF). Here we show by clonal analysis that Hedgehog (Hh), secreted from two distinct populations of cells has two distinct functions: It was well documented that Hh expression in the differentiating photoreceptor cells drives the morphogenetic furrow. Now we show that, in addition, Hh, secreted from cells at the posterior disc margin, is absolutely required for the initiation of patterning and predisposes ommatidial precursor cells to enter ommatidial assembly later. These two functions of Hh in eye patterning are similar to the biphasic requirement for Sonic Hh in patterning of the ventral neural tube in vertebrates. We show further that Hh induces ommatidial development in the absence of its secondary signals Wingless (Wg) and Dpp and that the primary function of Dpp in MF initiation is the repression of wg, which prevents ommatidial differentiation. Our results show that the regulatory relationships between Hh, Dpp, and Wg in the eye are similar to those found in other imaginal discs such as the leg disc despite obvious differences in their modes of development.
复眼的模式形成始于眼成虫盘的后缘，并向前朝着盘边缘推进。小眼分化的前进前沿由形态发生沟（MF）标记。在这里，我们通过克隆分析表明，从两个不同细胞群体分泌的刺猬蛋白（Hh）具有两种不同的功能：已有充分文献记载，在分化的感光细胞中Hh的表达驱动形态发生沟。现在我们表明，此外，从盘后缘细胞分泌的Hh对于模式形成的起始是绝对必需的，并且使小眼前体细胞随后易于进入小眼组装。Hh在眼模式形成中的这两种功能类似于脊椎动物腹侧神经管模式形成中对音猬因子（Shh）的双相需求。我们进一步表明，在没有其二级信号无翅（Wg）和Dpp的情况下，Hh诱导小眼发育，并且Dpp在MF起始中的主要功能是抑制wg，这可防止小眼分化。我们的结果表明，尽管眼、腿盘等其他成虫盘在发育模式上存在明显差异，但Hh、Dpp和Wg之间的调控关系是相似的。
