經典Wnt/β-catenin訊息傳遞路徑相關基因在瓢體蟲（Aeolosoma viride）前端再生的表現

Abstract

Aeolosoma viride為一種淡水生環節動物，擁有強大的再生能力，在切除頭部後，A. viride可以在五天內完成頭部再生。本研究成功選殖出A. viride 體內Wnt signaling pathway 相關基因Avi-wnt4、 Avi-wnt8, Avi-β-catenin及Avi-notum，並研究它們在頭部再生過程中的表現及調控。結果顯示：在切除頭部後，avi-wnt4、avi-β-catenin及avi-notum會在再生中的blastema中表現。而blastema中的β-catenin在再生過程會進入細胞核開啟canonical Wnt pathway.。在Wnt pathway抑制劑XAV939處理後，A. viride的頭部再生會受到抑制；然而，在Wnt pathway促進劑azakenpaulone處理後，A. viride的頭部再生也會受到抑制，但是XAV939和azakenpaulone對再生的抑制效果會因為處裡藥物的時間點不同而產生不同的效力。因此，根據實驗結果，我們推論canonical Wnt/β-catenin Signaling pathway在調控A. viride的頭部再生過程中需要先關閉後開啟。

Aeolosoma viride, a fresh water annelid, has been used as an animal model for regeneration study. After decapitation, in which the anteriormost 4 segments including the brain were removed, A. viride can regenerate its lost parts within five days. Among many physiological pathways, the canonical Wnt signaling pathway is known to play roles not only in development and stem cell fate determination but also in regeneration. In this study, genes encoding four different components of Wnt signaling pathway, Avi-wnt4, Avi-wnt8, Avi-β-catenin and Avi-notum, have been cloned. All of them were expressed in the newly regenerating cell mass, the blastema. In addition, this pathway exerts its effect by nuclear import of β-catenin, functioning as a transcription co-activator, it was demonstrated that β-catenin indeed localizes into the nucleus in cells of blastema during regeneration. This result indicates that the pathway is in an on state during A. viride regeneration. Furthermore, after treated with XAV939, a Wnt pathway inhibitor, the anterior regeneration of A. viride was obviously inhibited. This result supports that Wnt pathway is indispensable for proper head regeneration in A. viride. However, after treated with azakenpaulone, a Wnt pathway activator, the anterior regeneration of A. viride was also obviously inhibited. However, the inhibitory effects of XAV939 and azakenpaulone took place at different time points. Therefore, it can be inferred that the canonical Wnt signaling pathway is regulated differently in the regeneration process of A. viride. That is, this pathway should be inactivated at the beginning, and then be activated at late during the anterior regeneration.