Lipid Vesicle Fusion: Investigation, Generation and Manipulation of Cell-Membrane Mimics
Doktorsavhandling, 2011

Membrane fusion is essential for nerve-cell communication, for protein transport between cell organelles and the cell-membrane and for enabling the merger between virus and host membranes during virus infection. In this work, cell-membrane mimics were constructed and evaluated as models for studies of the membrane-fusion process. As a mimic of SNARE-proteins, known to induce fusion in secretory cells (exocytosis), short cholesterol-tagged DNA strands were used to facilitate fusion. The DNA strands were proven efficient as SNARE-protein substitutes in terms of bringing lipid vesicle fusion and content release about. This thus enabled reductionist and protein-free studies of some of the mechanisms behind lipid vesicle fusion. In particular, the fast kinetics of vesicle-content release upon fusion was possible to resolve using amperometry. The model system designed to be compatible with amperometric recordings generated data that could be directly compared with amperometric recordings from live cells. In combination with theoretical modeling, this has led us to suggest that the opening of the fusion pore is the rate-limiting step for content release in a protein-free system. In combination with the ability to systematically alter additional parameters, such as lipid composition, this model system may help resolving some of the still unanswered questions regarding the molecular mechanisms that control the exocytosis process. As a second approach, lipid vesicle fusion was used as a new means to form planar cell-membrane mimics on solid supports. It is demonstrated that such supported lipid bilayers (SLBs) could be made with complex lipid compositions that are generally prevented when alternative SLB-formation methods are used. In particular, successful formation of SLBs containing native cell membrane components was demonstrated. Furthermore, by forming such SLBs in microfluidic systems, spatial manipulation of cell-membrane-associated molecules was demonstrated. This, in turn, points towards the exciting possibility to both enrich and separate membrane proteins while in their native environment, potentially offering a new way to study this biologically and pharmacologically very important class of biomolecules.

TIRF microscopy

biomembranes

amperometry

exocytosis

cell mimic

model system

microfluidics

fluorescence resonance energy transfer

spreading lipid bilayers

membrane-receptor interactions

self-assembly

vesicles

FRET

diffusion

site-specificity

membrane fusion

micromanipulation

lipid bilayer

total internal reflection fluorescence microscopy

DNA

Kollektorn
Opponent: Ralf Richter

Författare

Lisa Simonsson Nyström

Chalmers, Teknisk fysik, Biologisk fysik

Formation and Diffusivity Characterization of Supported Lipid Bilayers with Complex Lipid Compositions

Langmuir,; Vol. 28(2012)p. 10528-10533

Artikel i vetenskaplig tidskrift

Continuous Lipid Bilayers Derived from Cell Membranes for Spatial Molecular Manipulation

Journal of the American Chemical Society,; Vol. 133(2011)p. 14027-14032

Artikel i vetenskaplig tidskrift

Site-Specific DNA-Controlled Fusion of Single Lipid Vesicles to Supported Lipid Bilayers

ChemPhysChem,; Vol. 11(2010)p. 1011-1017

Artikel i vetenskaplig tidskrift

A functioning artificial secretory cell

Scientific Reports,; Vol. 2(2012)p. no. 824-

Artikel i vetenskaplig tidskrift

Celler bygger upp alla levande organismer. Cellens ytterhölje kallas för cellmembran. Alla molkyler som transporteras in i eller ut från cellen måste passera cellmembranet. Exocytos är ett sätt att transportera molekyler ut från cellen. Molekyler som förvaras inuti vesiklar (30-500 nm sfäriska behållare) släpps ut från cellen genom fusion mellan vesikelns och cellens membran. Exocytos ansvarar bland annat för kommunikationen mellan nervceller. För att öka förståelsen kring de komplexa molekylära mekanismerna som möjliggör exocytos, har jag utvecklat förenklade modellsystem. Syftet är att kontrollera och variera olika parametrar för att utläsa relevant information för det naturliga systemet. Exempelvis har slutsatser kring mekanismer som kontrollerar hastigheten för signalöverföringen mellan nervceller kunnat dras. Fusion mellan vesikel och cellmembran resulterar i att molekyler i vesikelns membran levereras till cellmembranet. Detta har inspirerat till att använda membranfusion för att utveckla förenklade modellsystem av cellmembran, som innehåller viktiga membrankomponenter. Vissa membrankomponenter är vanliga måltavlor för medicinska molekyler. Studier och manipulation av dessa i sitt naturliga tillstånd, i cellmembranet, är svårt men viktigt och av intresse för exempelvis läkemedelsindustrin. Genom att kombinera ytbundna cellmembranliknande modellsystem med mikrofluidik och bioanalytiska metoder, kan rumslig manipulation och studier av membrankomponenter möjliggöras.

Styrkeområden

Nanovetenskap och nanoteknik

Livsvetenskaper och teknik

Materialvetenskap

Fundament

Grundläggande vetenskaper

Drivkrafter

Innovation och entreprenörskap

Ämneskategorier

Biofysik

ISBN

978-91-7385-630-0

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 3311

Kollektorn

Opponent: Ralf Richter

Mer information

Skapat

2017-10-07