The effect of oxycholesterols on thermo-induced membrane dynamics.

The effect of temperature change(s) on the dynamics of giant unilamellar vesicles containing oxidized and non-oxidized cholesterol was investigated and characterized. We have demonstrated that (i) major cholesterol auto-oxidation products, 7β-hydroxycholesterol (7β) and 7-ketocholesterol (7keto), rendered vesicles more responsive to temperature changes; (ii) 7keto imparted greater thermo-induced membrane dynamics than 7β; (iii) 7β and 7keto vesicles synergistically were more thermo-responsive than the individual oxysterols; (iv) the thermo-responsiveness of 7keto-containing vesicles was equivalent to that of 25 hydroxycholesterol (25OH)-containing vesicles; and (v) we have characterized the observed membrane dynamics. The results provide a new plausible mechanism: oxidative-stressed membranes in conjunction with temperature change induce membrane dynamics. These findings improve the mechanisms reported previously that attributed the induced dynamics solely to membrane oxidation.