Elucidation of cell membrane fluidity by updating the system from a model system to a biological system

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K03873
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 13040:Biophysics, chemical physics and soft matter physics-related
• Research Institution: Tohoku University
• Principal Investigator: Sakuma Yuka 東北大学, 理学研究科, 講師 (40630801)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: モデル細胞膜 / 細胞膜流動性 / 膜粘度 / ベシクル

Outline of Final Research Achievements

Since the membrane fluidity plays important roles in the cellular functions, the viscosity of model lipid membrane (GUV) has been investigated. Cell membranes are composed of not only lipids and proteins but also polysaccharide chain-anchored molecules, such as glycoproteins and glycolipids, which are expected to affect the membrane fluidity. To reveal the effects of grafted polymers on the membrane fluidity, in this study, we measured the membrane viscosity of polymer grafted GUVs. The obtained membrane viscosity of polymer-grafted GUVs increased with increasing polymer density up to several times. The increase of membrane viscosity of polymer -grafted GUVs is governed by the　contact interaction among polymer chains. To understand the difference in membrane fluidity between non-living and living cells, we also measured the membrane fluidity of unfertilized and fertilized eggs of C. elegans and ascidians.

Free Research Field

ソフトマター物理学，生物物理学

Academic Significance and Societal Importance of the Research Achievements

脂質、タンパク質、多糖類からなる細胞膜の流動性は、膜内の機能分子の輸送を通じて細胞機能を制御している。多糖鎖などの膜から伸びる高分子鎖は、膜の流動性に大きく影響することが予想されるが、その解明はまだなされていない。本研究では、高分子をグラフトしたモデル生体膜の膜粘度を高分子密度の関数として測定し、膜粘度が最大で数倍まで上昇することを見出した。さらに、　膜にグラフトした高分子鎖間の相互作用を考慮した理論モデルを立て、高分子鎖間の相互作用が膜粘度を上昇させることを明らかにした。本研究は、細胞膜の流動性制御を理解するための新たな知見を提供するものである。