Effect of sphingosine on domain morphology in giant vesicles

Sphingosine is a bioactive molecule which is known to participate in the regulation of a number of cellular processes such as apoptosis, cell differentiation, growth, etc. Sphingosine was observed to exhibit different domain morphology depending on the surrounding lipid matrix in biomimetic systems such as giant vesicles. Our current results showed that in a glycerophospholipid matrix sphingosine segregated in gel leaf-like domains whereas cholesterol presence increased its miscibility by melting gel domains in a concentration-dependent manner. Sphingosine and cholesterol did not form merging liquid domains on the micron scale as observed for sphingomyelin and cholesterol. However, we were able to visualize that sphingosine appears as a stabilizer and amplifier of domains in liquid-ordered phase by increasing the temperature of their formation and fraction. These results imply that sphingosine acts as a modulator of the lipid domain formation and thus it could exert its biological role, not only through direct binding to proteins, but also indirectly by influencing their sorting in membranes and modulating the processes of signal transduction.

Membrane microdomains: Effect of sphingosine on domain morphology in biomimetic systems as giant vesicles: sphingosine gel domains (A); melting of leaf-like gel domains in the presence of cholesterol (B); liquid/liquid Lo/Ld immiscibility with (C) and without (D) sphingosine. Sphingosine acts as a stabiliser (amplifier) of Lo domains.Figure optionsDownload high-quality image (55 K)Download as PowerPoint slideResearch highlights
► Sphingosine is a modulator of the lipid domain formation.
► Sphingosine segregates in gel leaf-like domains in glycerophospholipid matrix.
► Cholesterol increases sphingosine miscibility in a concentration-dependent manner.
► Sphingosine acts as a stabilizer and amplifier of domains in liquid-ordered phase.
► Sphingosine increases the temperature of Lo domain formation and their fraction.