Xenobiotic-Metabolism and Steroidogenic Enzyme Cytochrome P450 and Their Regulation---Bioinformatic and Functional Genomic Approach (III)

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Project title

Code/計畫編號

NSC98-2627-B019-001

Translated Name/計畫中文名

環境異質代謝與固醇合成酵素細胞色素P450及其調控---生物資訊與功能基因體學探討---(總計畫)生物資訊與功能基因體學探討(III)

Project Coordinator/計畫主持人

Chin-Hwa Hu

Funding Organization/主管機關

National Science and Technology Council

Co-Investigator(s)/共同執行人

李立安
陳逸然
張大慈
鄒文雄
白敦文

Department/Unit

Department of Bioscience and Biotechnology

Website

https://www.grb.gov.tw/search/planDetail?id=1895985

Year

2009

Start date/計畫起

01-08-2009

Expected Completion/計畫迄

01-07-2010

Co-Investigator(s)

Wen-Shyong Tzou

Bugetid/研究經費

2230千元

ResearchField/研究領域

生物技術(理)
生物科學

低氧誘發蛋白HIF1α與-2α以及細胞凋亡抑制蛋白survivin常在人類的癌細胞中有異常的表現，同時也在許多胚胎組織如中樞神經等廣泛表現，但是對於這些蛋白再胚胎發育中的角色一直都不甚清楚。在本論文中，我們證明了斑馬魚的HIF2α透過控制survivin基因birc5a與birc5b表現的方式，保護神經先驅細胞並且促進他們的細胞分化。以morpholino類寡核酸弱化HIF2α蛋白合成會造成斑馬魚胚胎內survivin基因birc5a與birc5b的轉錄活性下降，並且誘發p53-非依賴性細胞凋亡，因而造成神經細胞分化停止。另一方面，弱化birc5a and birc5b也會造成類似HIF2α弱化的狀況。而將HIF2α弱化後如果提供體外合成的birc5a and birc5b mRNA，可以大幅改善HIF2α弱化所造成的發育缺陷，顯示birc5a and birc5b的作用是在HIF2α控制的下游路徑。將hif2α, birc5a or -5b弱化會降低cdk inhibitors p27/cdkn1b and p57/cdkn1c的表現，同時也增加存活的神經先驅細胞內cyclin D1/ccnd1的表現。由微弱的elavl3/HuC神經細胞標示基因的表現以及增強的pcna以及nestin的表現顯示在HIF2α弱化的胚胎內，存活的神經先驅細胞大部分停留在快速增生的狀態而未進行末期的細胞分化工作。值得注意的是將birc5a弱化並沒造成細胞多倍體化，顯示斑馬魚survivin可能並未參與cytokinesis的工作。我們認為HIF2α所造成的胚胎發育缺陷，有部份是由survivin的短缺所造成。 Hypoxia-inducible factor (HIF) 1α and -2α and the inhibitor of apoptosis survivin represent prominent markers of many human cancers. They are also widely expressed in various embryonic tissues, including the CNS； however, little is known about their functions in embryos. Here, we show that zebrafish HIF2α protects neural progenitor cells and neural differentiation processes by up-regulating the survivin orthologues birc5a and birc5b during embryogenesis. Morpholino-mediated knockdown of hif2α reduced the transcription of birc5a and birc5b, induced p53-independent apoptosis and abrogated neural cell differentiation. Depletion of birc5a and birc5b recaptured the neural development defects that were observed in the hif2α morphants. The phenotypes induced by HIF2α depletion were largely rescued by ectopic birc5a and birc5b mRNAs, indicating that Birc5a and Birc5b act downstream of HIF2α. Knockdown of hif2α, birc5a or -5b reduced the expression of the cdk inhibitors p27/cdkn1b and p57/cdkn1c and increased cyclin D1/ccnd1 transcription in the surviving neural progenitor cells. The reduction in elavl3/HuC expression and enhanced pcna and nestin expression indicate that the surviving neural progenitor cells in hif2α morphants maintain a high proliferation rate without terminally differentiating. It is noteworthy that knockdown of birc5a did not cause polyploidy, indicating that the zebrafish survivin orthologues are probably not involved in cytokinesis. We propose that a subset of developmental defects attributed to HIF2α depletion is due in part to the loss of survivin activity.

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Xenobiotic-Metabolism and Steroidogenic Enzyme Cytochrome P450 and Their Regulation---Bioinformatic and Functional Genomic Approach (III)

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