Cardiovascular Research Institute and Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94143-2711, USA.
Development. 2010 Nov;137(22):3887-98. doi: 10.1242/dev.055871.
Paracrine Hedgehog (Hh) signaling regulates growth and patterning in many Drosophila organs. We mapped chromatin binding sites for Cubitus interruptus (Ci), the transcription factor that mediates outputs of Hh signal transduction, and we analyzed transcription profiles of control and mutant embryos to identify genes that are regulated by Hh. Putative targets that we identified included several Hh pathway components, mostly previously identified targets, and many targets that are novel. Every Hh target we analyzed that is not a pathway component appeared to be regulated by Hh in a tissue-specific manner; analysis of expression patterns of pathway components and target genes provided evidence of autocrine Hh signaling in the optic primordium of the embryo. We present evidence that tissue specificity of Hh targets depends on transcription factors that are Hh-independent, suggesting that `pre-patterns' of transcription factors partner with Ci to make Hh-dependent gene expression position specific.
旁分泌 Hedgehog (Hh) 信号通路调控许多果蝇器官的生长和模式形成。我们对 Cubitus interruptus (Ci) 的染色质结合位点进行了作图，Ci 是介导 Hh 信号转导的转录因子，我们分析了对照和突变胚胎的转录谱，以鉴定受 Hh 调控的基因。我们鉴定的推定靶标包括几个 Hh 途径成分，大多数是先前鉴定的靶标，还有许多是新的靶标。我们分析的每个不受途径成分调控的 Hh 靶标似乎都以组织特异性的方式受到 Hh 的调控；途径成分和靶基因表达模式的分析为胚胎视原基中的自分泌 Hh 信号提供了证据。我们提出的证据表明，Hh 靶标的组织特异性取决于与 Ci 无关的转录因子，这表明转录因子的“预模式”与 Ci 合作，使 Hh 依赖性基因表达具有位置特异性。
