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Title: | PTENB 調控斑馬魚原腸期胚細胞方向性遷移 PTENB Mediates Cell Migration during Gastrulation in Zebrafish |
Authors: | Yi-Ching Liu 劉怡青 |
Advisor: | 李士傑(Shyh-Jye Lee) |
Keyword: | 原腸腔,斑馬魚,PI3 kinase,細胞遷移,PTEN, gastrulation,PI3 kinase,zebrafish,Pten,convergence and extension, |
Publication Year : | 2010 |
Degree: | 碩士 |
Abstract: | 方向性細胞遷移是胚胎發育原腸腔時期形成三個主要胚層的主因。目前在斑馬魚關於此時期的研究所知,此種細胞遷移是藉由PI3 kinase磷酸化PIP2為PIP3所調控。Phosphatase and tensin homolog deleted on chromosome 10 (PTEN),是扮演與PI3 kinase相反作用的酵素,其主要作用是將PIP3上D3位置的磷酸根移除而成為PIP2。依此推測,Pten也可能在方向性細胞遷移的過程當中有所參與。因此我利用斑馬魚來探討抑制Pten的表現對於原腸腔時期細胞遷移有何影響。Pten在斑馬魚中有兩種同功異構物Ptena以及Ptenb,我運用ptenb的morpholino (MO)抑制了ptenb的表現之後發現細胞的方向性遷移受到了影響;此外雖然胚胎的形成並未受影響,然而其型態上的發育卻有所缺陷。而我們實驗室先前的實驗也利用PI3 kinase的抑制物,LY294002,削弱PI3 kinase的表現發現可以減弱Ptenb缺失所造成的缺陷,證實Ptenb對於細胞方向性遷移是藉由調控PIP2/PIP3之間的平衡而得之結果。進一步地,在ptenb受抑制的胚胎當中,位於側面具有聚合行為的細胞群其細胞極性也受到影響,同時觀察到肌動蛋白 (actin) 聚合程度有增加的趨勢。此外,我也發現,運用Cdc42的顯性負面(dominant-negative)分子T17NCdc42能夠抑制ptenb缺失所造成之缺陷。若是大量表現持續激活性之另一下游分子AKT1則可觀察到與ptenb 受抑制時同樣之現象,因此我認為此極性上的缺陷是來自於肌動蛋白聚合程度改變所影響而造成的結果。總體而言,Ptenb藉由調控PIP2/PIP3之間的平衡進一步調控了下游分子Cdc42以及Akt1進而調控肌動蛋白之聚合程度而影響了斑馬魚原腸腔時期的方向性細胞遷移。 During gastrulation, directional cell movements occur in the formation of three germ layers. Directional cell movements are known to be controlled by PI3 kinase by phosphorylating PIP2 to form PIP3 in zebrafish embryos. Phosphatase and tensin homolog deleted on chromosome 10 (Pten) is a counter enzyme of PI3 kinase by removing a phosphate group from PIP3. It is logical to hypothesize that Pten may also be involved in gastrulation cell migration. Here, I tested this hypothesis by investigating the effect of Pten knockdown on directed cell migration during gastrulation. I demonstrated that Ptenb, one of the Pten isoforms, regulates convergence and extension in zebrafish gastrulation by using the anti-sense morpholino oligo (MO). The effects of ptenb knockdown were through their control of PIP2/PIP3 balance, because previously in our lab showed that the Pten MO-induced defects could be rescued by PI3-kinase inhibitor, LY294002 and the knockdown of ptenb disturbed polarity and persistency of lateral convergent cells that was presumably via its regulation of actin dynamics, for the reason of actin polymerization was increased in the ptenb morphants. The downstream effectors, Akt1 and small GTPase Cdc42 would increase their activities in ptenb knockdown morphants; therefore, dominant negative Cdc42 was used and found to rescue the ptenb morphant. In addition, over-expression of human constitutively active akt1 mRNA showed similar convergent extension defects. In summary, I demonstrate here Ptenb by modulating PIP2/PIP3 signaling mediates directional cell migration by Akt1 and small GTPase to regulate actin polymerization during gastrulation in zebrafish. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/47337 |
Fulltext Rights: | 有償授權 |
Appears in Collections: | 動物學研究所 |
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