斑馬魚水解磷酸酯受器4功能之研究

The Investigation of LPA Receptor 4 Functions in Zebrafish

林予農(Yu-Nung Lin)

指導教授 ： 李心予

國立臺灣大學/生命科學院/動物學研究所/碩士(2012年)

https://doi.org/10.6342/NTU.2012.01978

摘要

水解磷酸酯 (lysophosphatidic acid) 是一種結構簡單的水解磷酯 (lysophospholipid)，它與許多生理作用如傷口癒合、癌症惡化、心血管活動、神經調節運作、生殖系統調節、血小板活化與毛髮生長等過程皆密切相關。水解磷酸酯主要經由一具有水解磷酯酶 (lysophospholipase D) 活性的酵素 (autotaxin) 催化磷酯 (phospholipid) 分解而成，並進一步作為膜外訊息傳遞分子，以活化不同受器，如水解磷酸酯受器1-6。為了解不同受器的功能，前人的研究利用催化水解磷酸酯生成酵素 (autotaxin) 基因被抑制的小鼠，分析在水解磷酸酯缺少的情況下小鼠所受到的影響，進而發現由於血管發育缺陷所導致的早期胚胎死亡。然而，在其他研究中，水解磷酸酯受器1-3基因被抑制的小鼠中並沒有類似的症狀出現。本研究探討水解磷酸酯受器4，以期發現其可能活化的下游途徑。藉由斑馬魚平台，在注射抑制基因表現分子而導致水解磷酸酯受器4缺少的早期斑馬魚胚胎中，發現不正常的發育現象。除了可能由血管滲漏與淋巴管回收體液不完全所導致的心臟水腫，也同時觀察到心跳速率與血液流速的明顯降低。另外，體節間縱向血管數目的減少及異常的生長方向，也顯示出血管發育的異常。但是，在運用注射大分子葡聚糖 (dextran, tetramethylrhodamine) 觀察循環系統的結果中，淋巴管的發育並沒有受到明顯影響。總結以上，我們認為在斑馬魚中，水解磷酸酯4有調控血管發育的可能性。

關鍵字

水解磷酸酯 ； 水解磷酸酯受器 ； 血管 ； 發育 ； 斑馬魚

並列摘要

Lysophosphatidic acid, LPA, is a structurally simple lysophospholipid. Derived from phospholipids through autotaxin catalyzation, LPA acts as an extracellular signaling molecule that activates various receptors, LPA1-6. Activation of these receptors induces wound healing, cancer progression, cardiovascular function, nervous system regulation, reproduction, platelet activation, hair growth, etc. To clarify the function of different LPA receptors, several knockout animals have been obtained. While the autotaxin deficient mice expressed the phenotype of embryonic lethality due to vascular defects, none of the single or double deficient LPA1-3 mice expressed similar phenotypes. In this study, I investigate the physiological roles of LPA4, which is structurally distinct from LPA1-3, using zebrafish as a model. LPA4 morpholino was microinjected into one-cell stage zebrafish embryo to knock down the expression level of LPA4 in embryos. In day two, edema around the pericardial region was observed, suggesting a vascular leakage or failure of lymphatic vessels to absorb body fluids in the LPA4 deficient embryos, which was similar to the result of a previous study where LPA1 was found to be essential for lymphatic vessel development in zebrafish. In addition, a significant decrease in heart rate and blood flow was observed in some individuals. Furthermore, the number of intersegmental vessels decreased, suggesting abnormal blood vessel development. However, the dextran uptake was not affected in the LPA4 knock down embryos, suggesting that the development of lymphatic vessels was normal. We conclude that LPA4 may regulate the vascular development in zebrafish.

並列關鍵字

lysophosphatidic acid ； G-protein coupled receptor ； blood vessel ； development ； zebrafish

參考文獻

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