Summary: | 碩士 === 國立陽明大學 === 生命科學暨基因體科學研究所 === 95 === unpaired (upd) encodes a secreted ligand for the Jak/STAT pathway. It is expressed at the central point of the posterior margin in the eye disc, the initiation site of the morphogenetic furrow (MF). Thus upd may play the role in MF determination. It had been shown that several signaling pathways are involved in MF initiation, such as N, Dpp, Hh and Wg. But it is still unclear what factors specify the expression of upd. To understand the regulatory network controlling upd expression, we checked the interactions between upd and several signaling pathways. Testing of gain-of-function and loss-of-function effects of these pathways on the expression of upd-lacZ suggested Hh and Dpp pathway cooperate with N signaling to activate upd expression at the posterior center of the eye disc. Furthermore, we found that Wg signaling may negatively regulate upd expression, and Upd was also involved in auto-regulation of its own expression. We are also interesting in finding the direct regulation of upd. We checked the direct regulation by enhancer identifications and binding site mutations of several transcriptional factors. We found N, Hh and Wg signaling may regulate upd through these enhancers.
In this study, we demonstrated the spatial and temporal control of upd expression. The intersection of N and Dpp, Hh signaling determines the upd expression. We also discovered a novel finding that Wg signaling restricts the upd expression in posterior center and Jak/STAT pathway may have auto-regulation to maintain upd expression.
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