Studies on the hemifusion of lipid bilayers

• Grant number: 23/11908-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: September 01, 2023
• End date: July 31, 2024
• Field of knowledge: Physical Sciences and Mathematics - Physics - Condensed Matter Physics
• Principal Investigator: Thais Azevedo Enoki Liarte
• Grantee: Guilherme Xavier Pinheiro
• Host Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 22/04046-4 - Investigating the asymmetry of the plasma membrane: model membranes mimicking healthy and tumor cells, and anti-tumor therapeutic strategies, AP.JP

Abstract

The plasma membrane is asymmetric in terms of lipid composition, meaning that the inner and the outer leaflets have different mixtures of lipids. With the advance of new methods and techniques, asymmetric lipid bilayers can be created in vitro, with controlled compositions. Here, we propose to explore the potential of creating asymmetric giant unilamellar vesicles (aGUVs) using the hemifusion method, proposed by Enoki and Feigenson (2019) (Biophysical Journal, 117, 1037). Briefly, the experimental procedure consists in inducing hemifusion between GUVs and a supported lipid bilayer (SLB). Hemifusion is the fusion of the GUV and the SLB outer leaflets, without the fusion of their inner leaflets. In our experimental protocol, hemifusion is initiated by calcium ions, and controlled by the addition of the calcium chelater, EDTA. Here, we propose to optimize steps of the protocols in order to obtain a better outcome: more aGUVs with a high percentage of lipid exchange. Previous reports show that calcium concentration, or the time that GUVs and SLB are connected, influence the percentage of lipid exchange.