HDL-membrane-interactions are highly influenced by the target membrane-lipid composition.

Abstract

Lipid transfer from lipoprotein particles to cells is essential for lipid homeostasis. High-density lipoprotein (HDL) particles are part in an important mechanism in cholesterol homeostasis in the body and are mainly captured by cell membrane-associated scavenger receptor class B type 1 (SR-B1) from the bloodstream. Recently we were able to demonstrate an additional concept of a receptor-independent interaction between lipoprotein particles and lipid membranes. The role of the different lipid composition, properties, and organisation of the target lipid membrane itself has not yet been investigated. This work addresses the question of how the interaction of HDL with synthetic membranes is regulated by varying the chain length, the degree of saturation as well as the binding groups of the head-tail region of the target membrane lipids. Total internal reflection microscopy and fluorescence correlation spectroscopy allowed us to demonstrate that target lipid membrane composed of ether lipids, significantly influences the preferred interaction region in phase separated membranes. In addition, when HDL particles were incubated with single-phase membranes containing ether lipids, we observed that the change in the diffusion coefficient of a fluorescent tracer lipid was significantly higher than for membranes without ether lipids. The receptor-independent interaction of lipoprotein particles with membranes is a fairly new concept and these new findings will help to refine the knowledge of lipoprotein particle biology as well the treatment in dyslipidaemia diseases.