A-to-I RNA editing是一種改變RNA序列的後轉錄修飾機制，可以增加基因產物的複雜性。ADAR (adenosine deaminase that act on RNA)是負責催化此一反應的酵素，在脊椎動物表現三種ADAR，分別為ADAR1、ADAR2、ADAR3。現今關於ADAR3活性及生理功能的研究相當有限。本論文以ADAR3 i2/e3 antisense morpholino（針對intron 2/exon 3連接處設計）降低ADAR3表現，研究ADAR3 knock down對斑馬魚胚體發育的影響。我們觀察到adar3 morphant胚體發育不正常，異常的表現型包括身體較小、中腦隆起、第四腦腔隆起膨大、對碰觸不敏感、最慢在胚體發育七天內死亡。為進一步瞭解ADAR3 i2/e3 antisense morpholino如何影響斑馬魚胚體發育，我們進行ngn1、neuroD、zNav1.6、otx2和p53的原位雜合染色，結果顯示這些基因在morphant腦部的表現量不同於野生種胚體。以acridine orange染色追蹤細胞凋亡，發現morphant的細胞凋亡多於野生種胚體，且在24 hpf為全身性，36 hpf則侷限在腦部。即時定量PCR分析顯示24 hpf morphant的neuroD mRNA表現量顯著下降，到了36 hpf其他神經相關基因：ngn1、gaba、grin1β，以及neuroD mRNA的表現量都有顯著下降。與細胞凋亡相關的基因，p53和mdm2，在morphant的表現量有非常顯著的上升。cxcr4b原位雜合染色顯示morphant PLL (posterior lateral line) primordium的移動沒有受到影響，但DiAsp染色顯示神經丘發育不完全。本研究結果顯示knock down ADAR3會影響斑馬魚早期腦部的發育。

Adenosine deaminases acting on RNA (ADARs) convert specific adenosines to inosines on dsRNA, which increase complexities of a gene product. ADAR3 is the third member of ADAR gene family; however the RNA editing activity of ADAR3 has not been demonstrated. To elucidate the biological functions of the ADAR3 during zebrafish development, the expression of adar3 was perturbed by the morpholino antisense oligonucleotide. The adar3 knock-down fish (morphant) developed abnormally. The abnormal phenotypes include small bodies, bulging midbrain, enlarged forth brain ventrical, touch insensitive, and death before 7 dpf (days post fertilization). I In situ hybridization showed that the expression of several neuronal markers differed in the brain regions between morphant and wildtype embryos. An elevated level of acridine orange positive granules was observed in the head and trunk of 24 hpf adar3 morphants, and an increase of apoptosis restricted to the head region at 36 hpf. The result of quantitative RT-PCR analyses revealed that the expression of neuroD in the 24 hpf and 36 hpf morphants was significantly reduced. In addition, expressions of many neuron-specific genes were significantly reduced in the 36 hpf morphant. The expressions of p53 and mdm2 mRNA increased dramatically in the 24 hpf and 36 hpf morphants. In situ hybridization of cxcr4b revealed that the migration of PLL (posterior lateral line) primordium was not effected in the morphants, but the results of activity stain suggested that the development of neuromasts was abnormal. These data suggested that ADAR3 participated in the early brain development of zebrafish.

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