- 學位論文
利用活體影像進行果蠅黏著型連接運輸功能之研究探討
Novel transport function of adherens junction revealed by live imaging in Drosophila
摘要
黏著型連接(adherens junction)為人所知的功能為調節細胞與細胞間的黏著。DE-cadherin和Echinoid是果蠅表皮細胞黏著型連接中主要的黏著分子。在此我們利用活體影像的技術追蹤果蠅胚胎表皮細胞中內吞Echinoid囊泡的移動，證明了Echinoid囊泡會與含有Rab5或Rab11的胞內體共位且一起移動。令人驚訝的是，這些含有Echinoid的胞內體會透過黏著型連接進行具方向性的細胞至細胞間移動。與此一致，Echinoid囊泡在細胞至細胞間的移動需要黏著型連接中DE-cadherin的存在。活體影像進一步顯示Echinoid囊泡會沿著與黏著型連接相關的微管(microtubule)進入鄰近的細胞，而此過程需要驅動蛋白(kinesin)的協助。重要的是，含有DE-cadherin和EGFR的囊泡也有細胞至細胞間移動的現象。總結而言，我們的研究結果揭示了黏著型連接的運輸功能。此外，這種以黏著型連接作為基礎的細胞間運輸提供了一個平台，讓連接蛋白和信號受體可以在相鄰細胞間做交換。
並列摘要
Adherens junctions are known for their role in mediating cell-cell adhesion. DE-cadherin and Echinoid are the principle adhesion molecules of adherens junctions in Drosophila epithelia. Here, using live imaging to trace the movement of endocytosed Echinoid vesicles in the epithelial cells of Drosophila embryos, we demonstrate that Echinoid vesicles co-localize and move with Rab5- or Rab11-positive endosomes. Surprisingly, these Echinoid-containing endosomes undergo directional cell-to-cell movement, through adherens junctions. Consistent with this, cell-to-cell movement of Echinoid vesicles requires the presence of DE-cadherin at adherens junctions. Live imaging further revealed that Echinoid vesicles move along adherens junction-associated microtubules into adjacent cells, a process requiring a kinesin motor. Importantly, DE-cadherin- and EGFR-containing vesicles also exhibit intercellular movement. Together, our results unveil a transport function of adherens junctions. Furthermore, this adherens junctions-based intercellular transport provides a platform for the exchange of junctional proteins and signaling receptors between neighboring cells.