Figure 9

Characterization of sterol distributions in lipid membranes in wild-type, knockout and knockout-transgenic lungs. Panel A shows the distributions of protein and phosphate in membrane fractions from sucrose gradients of WT (open circles), Dhcr7^-/-Tg- (closed circles) and Dhcr7^-/-Tg+ (filled diamonds) lungs. Fractions 2–4 represent buoyant fractions indicative of rafts. Panel B shows the distribution of cholesterol, Panel C that for precursor sterols 7/8DHC and Panel D that for total sterol (symbols as above). While the total sterol profiles are indistinguishable (Panel D), precursor sterols are increased and cholesterol decreased in the lungs from knockout animals (Panels B and C). Note that the distribution of precursor sterols is also bimodal in knockout lungs and the improvement of the cholesterol/precursor ratio by the Tg status. Quantitative comparison of sterol composition in rafts (fraction 2~4) and non-rafts (fractions 8~11) in WT, Dhcr7^-/-Tg- and Dhcr7^-/-Tg+ lungs was performed on three separate samples and data were normalized to organic-phosphate, Panel E and F. Results are expressed as mean ± SD. Genotypes are as indicated. See Results for discussion.