DHA-Induced Changes of Supported Lipid Membrane Morphology

Abstract

Docosahexaenoic acid (DHA) is a polyunsaturated long fatty acid known to have fundamental effects on cell membrane function. Here, the effect of DHA on phosphocholine-supported lipid bilayers was measured using the quartz crystal microbalance with dissipation monitoring (QCM-D) technique. Above a concentration of 60 muM (i.e., near the critical micelle concentration), DHA had drastic effects on the viscoelastic properties of the supported membranes, suggesting a more complex process and structure than simple insertion of molecules in the bilayer. Fluorescence microscopy revealed the spontaneous formation of elongated out-growths from the bilayers, which were remarkable for their length ( approximately 100 mum) and extensive coverage of the surface. These results demonstrate the applicability of QCM-D as a method to screen for conditions where membrane remodeling occurs but also that complementary techniques are required to describe in more detail the changes in viscoelastic properties of the membrane. These results are highly relevant for the present rapid development in the field of model lipid membranes aiming toward increased knowledge about processes occurring at biological surfaces.

Docosahexanoic Acid-Induced Coronary Arterial Dilation: Actions of 17S-Hydroxy Docosahexanoic Acid on K+ Channel Activity

“…17S-HDHA may directly interact with and change the conformation of BK Ca channels, leading to increased channel activity. As reported by Thid et al (2007), DHA at high concentrations (more than 6.0 ϫ 10 Ϫ5 M) dramatically changed the viscoelastic properties of the phosphocholine-supported lipid bilayers. Thus, DHA at high concentrations is more likely to exert its effects as a nonspecific lipid compound that modifies biophysical properties of membranes, which results in the alteration of BK Ca channel activities.…”

Confined Bilayers Passively Regulate Shape and Stress

“…In this Letter, we characterize a generic mechanical mechanism by which stressed membranes delaminate from their confining structure to form stable, highly curved tubular and spherical protrusions. In biomimetic systems, protrusions form out of confined membranes upon straining the membrane-supporting surface [3,4] or upon incorporating lipids or peptides in supported bilayers [5][6][7]. Similar processes have been observed in cells, where the plasma membrane bulges into blebs [8] and microvesicles [9] upon contraction of the underlying actin cortex, or forms tubular invaginations away from the substratum in shrinking adherent cells [10].…”

Evidence of a DHA Signature in the Lipidome and Metabolome of Human Hepatocytes

“…It is generally accepted that supplemented DHA is mainly incorporated into cell membrane PL, and this is known to have fundamental effects on membrane function [27]. The poor affinity of cholesterol for LC-PUFA promotes the formation of highly disordered membrane (non-raft) domains [28], which coexist with highly ordered lipid rafts, that are enriched in sphingolipids and cholesterol.…”