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Published on: September 16, 2020
Macrophage mitochondrial damage from StAR transport of 7-hydroperoxycholesterol: implications for oxidative
Witold Korytowski1, Katarzyna Wawak2, Pawel Pabisz2
1Department of Biochemistry, Medical College of Wisconsin, Milwaukee, WI, USA; Department of Biophysics, Jagiellonian University, Krakow, Poland.
Abstract:
StAR family proteins in vascular macrophages participate in reverse cholesterol transport (RCT). We hypothesize that under pathophysiological oxidative stress, StARs will transport not only cholesterol to macrophage mitochondria, but also pro-oxidant cholesterol hydroperoxides (7-OOHs), thereby impairing early-stage RCT. Upon stimulation with dibutyryl-cAMP, RAW264.7 macrophages exhibited a strong time-dependent induction of mitochondrial StarD1 and plasma membrane ABCA1, which exports cholesterol. 7α-OOH uptake by stimulated RAW cell mitochondria (like cholesterol uptake) was strongly reduced by StarD1 knockdown, consistent with StarD1 involvement. Upon uptake by mitochondria, 7α-OOH (but not redox-inactive 7α-OH) triggered lipid peroxidation and membrane depolarization while reducing ABCA1 upregulation. These findings provide strong initial support for our hypothesis.
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