Chlordecone increased subcellular distribution of scavenger receptor class B type II to murine hepatic microsomes without altering cytosolic cholesterol binding proteins

Abstract

Pretreatment of male C57BL/6 mice with low doses of the persistent organochlorine pesticide, chlordecone (CD), stimulated biliary excretion of exogenous cholesterol (CH) up to 3-fold. Increased biliary excretion occurred without changes in hepatic ATP-binding cassette transporter G8 (ABCG8) of the bile canaliculus or scavenger receptor class B type I (SR-BI) of the sinusoidal surface. A variety of tissues express scavenger receptor class B type II (SR-BII) and this protein was identified as a splice variant from the SR-BI gene. Although the function of SR-BII has not been elucidated it may play a role in CH homeostasis and trafficking distinctly different than SR-BI. Western blotting demonstrated that a single dose of CD promoted subcellular distribution of SR-BII to murine hepatic microsomes about 2.2-fold when compared to controls without effect on liver crude membrane SR-BII content. This was consistent with increased vesicular CH trafficking. Relative quantification of hepatic cytosolic proteins in a fraction that sequestered [ 14C]CH by mass spectrometry (MS) indicated no role for cytosolic CH binding proteins in CD altered CH homeostasis. Western blotting verified no effect of CD on liver fatty acid-binding protein (L-FABP) in cytosol. MS detected a statistically significant increase in myosin-9, which was also consistent with increased vesicular trafficking.