25-Hydroxycholesterol Effect on Membrane Structure and Mechanical Properties

Cholesterol is responsible for the plasticity of plasma membranes and is involved in physiological and pathophysiological responses. Cholesterol homeostasis is regulated by oxysterols, such as 25-hydroxycholesterol. The presence of 25-hydroxycholesterol at the membrane level has been shown to interfere with several viruses' entry into their target cells. We used atomic force microscopy to assess the effect of 25-hydroxycholesterol on different properties of supported lipid bilayers with controlled lipid compositions. In particular, we showed that 25-hydroxycholesterol inhibits the lipid-condensing effects of cholesterol, rendering the bilayers less rigid. This study indicates that the inclusion of 25-hydroxycholesterol in plasma membranes or the conversion of part of their cholesterol content into 25-hydroxycholesterol leads to morphological alterations of the sphingomyelin (SM)-enriched domains and promotes lipid packing inhomogeneities. These changes culminate in membrane stiffness variations.

Automated summary

The presence of 25-hydroxycholesterol interferes with viruses' entry into target cells by inhibiting cholesterol's lipid-condensing effects, ultimately making the bilayers less rigid. This study suggests that incorporating 25-hydroxycholesterol in plasma membranes or converting some of their cholesterol content into 25-hydroxycholesterol can lead to morphological alterations and promote inhomogeneities in lipid packing, resulting in changes in membrane stiffness.