Proximo-Distal Patterning in the Drosophila Appendages

项目描述（由申请人提供）：本项目以黑腹果蝇发育中的腿为模型系统，研究发育生物学中的基本问题。除了有前后轴（AP）和背腹轴（DV）外，成熟的腿和所有附属物一样，也有近端远端轴（PD）。与AP轴和DV轴不同，PD轴必须在发育中的胚胎的每个胸椎半段内重新形成。在果蝇中，腿原基首先被识别为约30个表达同源域编码Distalless （Dll）基因的细胞群。到幼虫发育结束时，假定的腿有大约20,000个细胞和沿PD轴的几个确定的区域。这个项目的目标是了解这些细胞是如何获得它们的位置信息的。通常，使用“自下而上”的方法，其中详细剖析驱动PD基因表达的顺式调控模块（crm），以确定控制其活动的上游输入。通过这种方式，一个CRM和基因活动的网络将产生。在下一个资助期，将特别关注1)最近端的PD结构域，它共同表达同源胸（hth），编码同源结构域转录因子，和teasht (tsh)，编码锌指核因子；2)最远端的PD结构域，由于表皮生长因子受体途径的活性而进一步阐述。此外，我们还将利用以crm为中心和靶基因的方法，研究由脊椎动物Sp8、dSp1和buttonhead （btd）的果蝇同源基因编码的两个“腹侧识别”因子的作用。总之，这些实验将使我们更好地理解位置信息是如何在分裂细胞中产生的，利用转录因子和信号通路

DESCRIPTION (provided by applicant): This project addresses fundamental questions in developmental biology using the developing leg of Drosophila melanogaster as the model system. In addition to having antero-posterior (AP) and dorso- ventral (DV) axes, the mature leg, as all appendages, also has a proximo-distal (PD) axis. Unlike the AP and DV axes, the PD axis must form de novo, within each thoracic hemisegment of a developing embryo. In the fly, the leg primordia are first identifiable as a cluster of ~30 cells that express the homeodomain-encoding Distalless (Dll) gene. By the end of larval development, the presumptive leg has ~20,000 cells and several defined domains along the PD axis. The goal of this project is understand how these cells obtain their positional information. Generally, a 'bottom-up' approach is used, in which cis-regulatory modules (CRMs) that drive the expression of PD genes are dissected in detail, to identify the upstream inputs that control their activities. In ths way, a network of CRM and gene activities will be generated. In the next funding period, particular attention will be given to 1) the most proximal PD domain, which co-expresses homothorax (hth), which encodes a homeodomain transcription factor, and teashirt (tsh), which encodes a Zn-finger nuclear factor and 2) the most distal PD domain, which is further elaborated due to the activities of the Epidermal Growth Factor Receptor pathway. In addition, the role of two 'ventral-identity' factors, encoded by the Drosophila homologs of vertebrate Sp8, dSp1 and buttonhead (btd), will be investigated, using both a CRM-centric and target gene approaches. Altogether, these experiments will lead to a better understanding of how positional information is generated in dividing cells, using transcription factors and signaling pathways that are conserved from flies to man.