Ectopic expression of seven-up causes cell fate changes during ommatidial assembly.
Ectopic expression of seven-up causes cell fate changes during ommatidial assembly.
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发表时间：
1993-08
期刊：
影响因子：
4.6
通讯作者：
Y. Hiromi;M. Mlodzik;S. West;G. Rubin;C. Goodman
中科院分区：
文献类型：
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作者：
Y. Hiromi;M. Mlodzik;S. West;G. Rubin;C. Goodman
在果蝇小眼发育过程中，小眼簇内的单个细胞被选择成为R7感光神经元。七喜基因已被证明在这一过程中发挥作用，阻止其他四个感光细胞前体，R3/R4/R1/R6，采用R7细胞的命运。七喜基因编码一种类固醇受体样分子，该分子仅在发育中的果蝇小眼中需要七喜功能的四种细胞中表达。我们通过错误表达七喜异构体研究了七喜空间限制性表达的功能意义。正如seven-up在R3/R4/R1/R6中执行的功能所预期的那样，seven-up的普遍表达导致R7细胞转变为R1-R6细胞命运。此外，根据表达的时间和空间模式，产生各种其他表型，包括R7细胞的丢失和额外R7细胞的形成。在接近形态发生沟的地方普遍表达seven-up会干扰R8的分化，导致不能表达boss蛋白（sevenless受体酪氨酸激酶的配体），从而导致R7细胞丢失。额外的R7细胞是通过招募非神经元视锥细胞作为光感受器神经元，以一种无7和无7的新娘的独立方式形成的。因此，时空模式的七喜表达起着至关重要的作用，在控制的数量和细胞起源的R7神经元的小眼。我们的研究结果还表明，七喜不仅控制感光细胞亚型之间的决定，而且神经元和非神经元的命运。
During Drosophila ommatidial development, a single cell is selected within the ommatidial cluster to become the R7 photoreceptor neuron. The seven-up gene has been shown to play a role in this process by preventing four other photoreceptor precursors, R3/R4/R1/R6, from adopting the R7 cell fate. The seven-up gene encodes a steroid receptor-like molecule that is expressed only in those four cells that require seven-up function in the developing Drosophila ommatidium. We have examined the functional significance of the spatially restricted expression of seven-up by misexpressing seven-up isoforms. As expected from the function that seven-up performs in R3/R4/R1/R6, ubiquitous expression of seven-up causes transformation of the R7 cell to an R1-R6 cell fate. In addition, depending on the timing and spatial pattern of expression, various other phenotypes are produced including the loss of the R7 cell and the formation of extra R7 cells. Ubiquitous expression of seven-up close to the morphogenetic furrow interferes with R8 differentiation resulting in failure to express the boss protein, the ligand for the sevenless receptor tyrosine kinase, and the R7 cell is lost consequently. Extra R7 cells are formed by recruiting non-neuronal cone cells as photoreceptor neurons in a sevenless and bride of sevenless independent way. Thus, the spatiotemporal pattern of seven-up expression plays an essential role in controlling the number and cellular origin of the R7 neuron in the ommatidium. Our results also suggest that seven-up controls decisions not only between photoreceptor subtypes, but also between neuronal and non-neuronal fates.