Electron microscopic analysis of lipid clusters in the inner leaflet of plasma membrane

2018 Fiscal Year Final Research Report

• Project/Area Number: 15K08167
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: General anatomy (including histology/embryology)
• Research Institution: Institute of Physical and Chemical Research
• Principal Investigator: Murate Motohide 国立研究開発法人理化学研究所, 開拓研究本部, 研究員 (30311369)
• Project Period (FY): 2015-04-01 – 2019-03-31
• Keywords: 細胞膜 / 脂質二重層 / ホスファチジルセリン / ホスファチジルエタノールアミン / 免疫電子顕微鏡法 / ショウジョウバエ / スクランブラーゼ / フリッパーゼ

Outline of Final Research Achievements

We examined transbilayer distribution of phosphatidylethanolamine (PE) and phosphatidylserine (PS) in the plasma membrane of normal and lipid transfer protein-depleted Drosophila cells by freeze-fracture replica immunoelectron microscopy. Our results indicate that both lipids were considerably localized in the outer leaflet, in addition to the inner leaflet of normal cell plasma membranes, whereas they distributed almost restrictedly in the inner leaflet of mammalian cell plasma membranes as reported by our previous studies. This remarkable distribution of PS in the plasma membranes was disturbed in flippase-depleted cells, but it was not affected in scramblase-depleted cells. Futhermore, the depletion of neither scrambrase nor flippase influenced the transbilayer distribution of PE. These results suggest that the mechanism of formation and maintenance of lipid distribution between two leaflets is different in each species.

Free Research Field

細胞生物学

Academic Significance and Societal Importance of the Research Achievements

本研究により明らかにされたショウジョウバエ細胞における細胞膜脂質二重層の内外層における脂質の対称分布は、これまで哺乳類細胞を用いて解析され、また認識されてきた非対称分布とは大きく異なり、細胞膜の脂質分布の多様性を示すとともに、細胞膜研究に対する新たな認識を提供することができた。また、脂質の分布に影響を及ぼすと考えられている酵素を欠損させても、すべての脂質の分布に影響を及ぼすわけではないことを明らかにし、脂質分布の形成と維持の機構に関する知見を提供することができた。