Rho Mediates Cytokinesis and Gastrulation via ROCK in Zebrafish

Rho經由ROCK調控斑馬魚胞質分裂與原腸化

賴時磊(Shih-Lei Lai) ； 李士傑(Shyh-Jye Lee)

《Acta Zoologica Taiwanica》 14卷2期 (2004/10) Pp. 103-104

https://doi.org/10.6576/AZT.2004.14.(2).7

摘要

在早期胚胎發育的過程，大量的細胞骨架發生重組的現象。其中，小GTP水解酵素(small GTPases)例如Rho，Rac，和Cdc42等，是調控細胞骨架訊息傳導的重要因子。爲了研究Rho如何調控早期胚發育，我們將Rho抑制劑細菌毒素Clostridium botulinum C3-exoenzyme（簡稱C3）利用顯微注射打入斑馬魚的早期胚以抑制Rho的活性。我們發現隨著施打C3劑量的升高，斑馬魚的卵裂(cleavage)以及原腸化(gastrulation)初期的外包過程(epiboly)被阻礙的程度越嚴重，但若同時注射持續活化態的RhoA與Rac1則可以拯救或防止C3造成的現象，然而Cdc42卻不能。再加上dominant-negative Rac1和Cdc42並不會造成前述的現象，所以我們推論只有Rho對早期斑馬魚胚的卵裂及原腸化是必須的。此外，當注射Y-27632，一種Rho激酶(Rho-kinase, ROCK)的拮抗物時，同樣會抑制卵裂與原腸化。最後，斑馬魚的色素生成(melanogenesis)以及色素細胞的出現，在一部分被C3注射的魚卵中甚至出現延遲的現象，而這種現象並沒有出現在被Y-27632注射的魚卵。這些結果顯示Rho調控斑馬魚早期發育中卵裂與原腸化經由ROCK的訊息傳導路徑，而Rho調控色斑生成則經由目前尚未判定的路徑。

關鍵字

Rho ； ROCK ； 卵裂 ； 外包 ； 色斑生成 ； 斑馬魚

並列摘要

Massive cytoskeletal reorganization occurs during early embryonic development. Small GTPases, including Rho, Rac and Cdc42, are key molecular switches in cytoskeletal signaling. To study the regulation of embryonic development by Rho, we microinjected Clostridium botulinum C3-exoenzyme (C3) into zebrafish embryos. We found that C3 inhibited early cleavage and blocked subsequent epiboly in a dose-dependent manner. Constitutively active RhoA and Rac1, but not Cdc42, could rescued the C3-induced defects. Since dominant negative Rac1 or Cdc42 failed to affect cytokinesis, it was concluded that only Rho is required. Y-27632, an antagonist of rho-associated kinase (ROK/ROCK), also inhibited cytokinesis and gastrulation. Finally, we demonstrated that the melanogenesis and appearance of pigment cells was delayed in a portion of C3-treated embryos. In contrast, no pigmentation defect was noticed in Y-27632-treated embryos. These results suggest that Rho mediates cytokinesis and gastrulation via a ROK/ROCK-dependent pathway. Rho may also regulate pigmentation in zebrafish through an as yet unidentified mechanism.

並列關鍵字

Rho ； ROCK ； cytokinesis ； epiboly ； pigmentation ； zebrafish