Basdicmolecularmechanisms for tissue and organ formaiton: HH and FGF-dependent and regulation of positional information and compartment formation

在本研究中，我们研究了果蝇复眼，气管，腿和内脏中胚层作为模型系统的发展的基本分子机制。在复眼中，重复使用已经分化的小眼细胞发出的Spitz信号触发了大约10种不同类型细胞的分化。我们发现的证据表明，新招募的小眼细胞的细胞命运的选择严格取决于他们的发育潜力和发育潜力的形成是由特定区域的prepattern基因表达。Breathless~ranchless信号的空间和时间调节活性对气管发育至关重要。我们表明，晚期btl表达是无分支/无呼吸信号传导的靶标，因此，无分支/无呼吸信号传导包含正反馈环，其可以保证新鲜受体持续供应到生长的气管分支细胞的膜。我们还表明，高水平的HH si ...更多信息 咀嚼活动对于腿的中间区域的图案化是必不可少的。在中期至晚期的第三龄滞后盘，高水平的HH信号抑制转录的pxb，一个新发现的基因编码的跨膜蛋白特异性表达在前室。错误表达实验表明，Pxb可能作为HH信号衰减剂，能够在HH-Ptc相互作用之前起作用，这表明腿盘中的HH信号包括pxb抑制介导的正反馈回路，运行内脏中胚层产生环状内脏肌肉。已经证明，躯干内脏中胚层旁段通过连接蛋白的表达被细分为至少两个域。我们通过研究更多的内脏中胚层基因，包括HH和FGF，扩展了这一点。外胚层HH和Wg差异调节躯干内脏中胚层中的位变异构靶的表达。HH在PS3中的表达似乎是正常Dpp表达和胃盲囊形成所必需的。发现Vmw中的无分支（FGF）可作为气管内脏分支最初出芽的指南。因此，响应于外胚层指示信号而组织的Vm的同色异谱模式通过自体调节在稍后的时间得以维持，是中肠形态发生所需的，并对气管、外胚层衍生物发挥反馈作用。少

In the present study, we examined basic molecular mechanisms of development using compound eyes, trachea, legs and visceral mesoderm in Drosophila as model systems. In compound eyes, reiterative use of Spitz signals emanating from already differentiated ommatidial cells triggers the differentiation of around ten different types of cells. We showed evidence that the choice of cell fate by newly recruited ommatidial cells strictly depends on their developmental potential and that developmental potential formation is governed by region-specific prepattern gene expression. Spatial y and temporally regulated activity of Breathless~ranchless signaling is essential for trachea development. We showed that late btl expression is a target of Branchless/Breathless signaling and hence, Branchless/Breathless signaling contains a positive feedback loop, which may guarantee a continuous supply of fresh receptors to membranes of growing tracheal branch cells. We also showed that hi g hI evels of HH si … More gnaling activity are essential for medial-region patterning in legs. In mid-to-late third instar lag discs, high levels of HH signals repress the transcription of pxb, a newly identified gene encoding as transmembrane protein expressed specifically in the anterior compartment. Misexpression experiments indicated that Pxb may serve as a HH signaling attenuator capable of acting prior to HH-Ptc interactions, suggesting tha HH signaling in leg discs includes a pxb-repression-mediated positive feedback loop, run visceral mesoderm gives rise to circular visceral muscles. It has been demonstrated that the trunk visceral mesoderm parasegment is subdivided into at least two domains by connectin expression. We extended this by examining a greater number of visceral mesodermal genes including HH and FGF. Ectodermal HH and Wg differentially regulate the expression of the metameric targets in trunck visceral mesoderm. HH expression in PS3 appeared required for normal Dpp expression and gastric caesum formation. Branchless(FGF) in Vmw as found to serve as a guide for the initial budding of tracheal visceral branches. The metameric pattern of Vm, organized in response to ectodermal instructive signals, is thus maintained at a later time via autoregu I ation, is required for midgut morphogenesis and exerts feedback effect on trachea, ectodermal derivatives. Less