Strutt D I, Mlodzik M
Differentiation Programme, EMBL, Heidelberg, Germany.
Mech Dev. 1996 Aug;58(1-2):39-50. doi: 10.1016/s0925-4773(96)00555-2.
The hedgehog signalling pathway is a conserved mechanism which acts in inductive processes in both vertebrate and invertebrate development to direct growth and patterning. In Drosophila, the secreted Hedgehog protein acts as a signal to induce non-autonomous activation in adjacent cells of either the decapentaplegic or wingless genes (both of which encode growth factor-like molecules), via inactivation of patched activity. In the eye disc, this pathway drives progression of the morphogenetic furrow, while in the wing (and leg and antennal) discs it is required to set up an organising centre along the anteroposterior compartment boundary. We have compared the regulation and function of hedgehog pathway activity in the eye and wing discs, and find that there are significant differences. Whereas in the wing disc, engrailed function is required for hedgehog expression, in the eye disc activation and maintenance of hedgehog expression is achieved independently of engrailed. Regulation of decapentaplegic expression also differs: in the wing disc it is repressed in the anterior compartment by patched and in the posterior compartment by engrailed. In the eye disc, however, it is repressed posterior to the morphogenetic furrow in the absence of either patched or engrailed activity. We conclude that in the eye disc there are novel aspects to hedgehog pathway function. Moreover, engrailed does not play an essential conserved role.
刺猬信号通路是一种保守机制，在脊椎动物和无脊椎动物发育的诱导过程中发挥作用，指导生长和模式形成。在果蝇中，分泌的刺猬蛋白作为一种信号，通过使patched活性失活，诱导相邻细胞中decapentaplegic或wingless基因（两者都编码生长因子样分子）的非自主激活。在眼盘中，该通路驱动形态发生沟的进展，而在翅（以及腿和触角）盘中，它需要沿着前后区室边界建立一个组织中心。我们比较了眼盘和翅盘中刺猬信号通路活性的调节和功能，发现存在显著差异。在翅盘中，刺猬蛋白的表达需要engrailed的功能，而在眼盘中，刺猬蛋白表达的激活和维持独立于engrailed实现。decapentaplegic表达的调节也不同：在翅盘中，它在前区室被patched抑制，在后区室被engrailed抑制。然而，在眼盘中，在没有patched或engrailed活性的情况下，它在形态发生沟后方被抑制。我们得出结论，在眼盘中，刺猬信号通路功能有新的方面。此外，engrailed并不发挥必不可少的保守作用。
