25-hydroxycholesterol interacts differently with lipids of the inner and outer membrane leaflet – The Langmuir monolayer study complemented with theoretical calculations. Issue 211 (July 2021)

• Record Type: Journal Article
• Authors: Wnętrzak, Anita; Chachaj-Brekiesz, Anna; Kuś, Karolina; Filiczkowska, Anna; Lipiec, Ewelina; Kobierski, Jan; Petelska, Aneta D.; Dynarowicz-Latka, Patrycja
• Is Part Of: Journal of steroid biochemistry and molecular biology. Issue 211(2021)
• Publication Date: 2021-07
• Subjects: AFM atomic force microscope -- BAM Brewster angle microscope -- PM–IRRAS Polarization modulation–infrared reflection–absorption spectroscopy -- DFT Density Functional Theory, (DFT) -- LB Langmuir-Blodgett -- chol cholesterol -- 25−OH 25–hydroxycholesterol -- 7α−OH 7α–hydroxycholesterol -- 7β−OH 7β–hydroxycholesterol -- 7–K 7–ketocholesterol -- 24−OH 24S–hydroxycholesterol -- 27−OH 27–hydroxycholesterol -- PC phosphatidylcholine -- PE phosphatidylethanolamine -- DPPC 1, 2–dipalmitoyl–sn–glycero–3–phosphocholine -- POPC 1–palmitoyl–2–oleoyl–sn–glycero–3–phosphocholine -- DOPC 2–dioleoyl–sn–glycero–3–phosphocholine -- DPPE 1, 2–dipalmitoyl–sn–glycero–3–phosphoethanolamine -- POPE 1–palmitoyl–2–oleoyl–sn–glycero–3–phosphoethanolamine -- DOPE 1, 2–dioleoyl–sn–glycero–3–phosphoethanolamine; Oxysterols -- 25–hydroxycholesterol -- Interactions -- Langmuir monolayers; Steroid hormones -- Periodicals; Biochemistry -- Periodicals; Hormones -- Periodicals; Molecular Biology -- Periodicals; Hormones stéroïdes -- Périodiques; Steroid hormones; Periodicals; 572.579
• DOI: 10.1016/j.jsbmb.2021.105909
• Languages: English
• ISSNs: 0960-0760

Abstract

Graphical abstract: Highlights: 25−OH has been investigated in mixtures with main membrane phospholipids (PC and PE). Strength of interactions depends mainly on the type of polar group. 25−OH interactions with PC are more favorable than interactions with PE. 25−OH membrane translocation has been confirmed to occur without orientation changes. Abstract: 25–hydroxycholesterol (25−OH), a molecule with unusual behavior at the air/water interface, being anchored to the water surface alternatively with a hydroxyl group at C(3) or C(25), has been investigated in mixtures with main membrane phospholipids (phosphatidylcholines – PCs, and phosphatidylethanolamines – PEs), characteristic of the outer and inner membrane leaflet, respectively. To achieve this goal, the classical Langmuir monolayer approach based on thermodynamic analysis of interactions was conducted in addition to microscopic imaging of films (in situ with BAM and after transfer onto mica with AFM), surface–sensitive spectroscopy (PM–IRRAS), as well as theoretical calculations. Our results show that the strength of interactions is primarily determined by the kind of polar group (strong, attractive interactions leading to surface complexes formation were found to occur with PCs while weak or repulsive ones with PEs). Subsequently, the saturation of phosphatidylcholines apolar chain(s) was found to be crucial for the structure of the formed complexes. Namely, saturated PC (DPPC) does not have preferences regarding the orientation of 25−OH molecule in surface complexes (which results in the two possible 25−OH arrangements), while unsaturated PC (DOPC) enforces one specific orientation of oxysterol (with C(3)−OH group). Our findings suggest that the transport of 25−OH between inner and outer membrane leaflet can proceed without orientation changes, which is thermodynamically advantageous. This explains results found in real systems showing significant differences in the rate of transmembrane transport of 25−OH and the other chain–oxidized oxysterols compared to their ring–oxidized analogues or cholesterol.