Physiological function of ABCG1

Since ATP-binding cassette transporter A1 (ABCA1) was discovered as the cause of Tangier disease and familial high-density lipoprotein (HDL) deficiency, many investigators have been interested in the relationship between ABC transporters and the mechanism underlying abnormal lipid metabolism. ABCG1 is an ABC half transporter that facilitates efflux excess cholesterol from macrophages. To elucidate the potential physiological role of ABCG1, we have initiated a series of studies overexpressing ABCG1, using an adenovirus vector (rABCG1-Adv) in C57BL mice. Overexpression of ABCG1 in the liver of mice using recombinant ABCG1 vectors results in decreased plasma HDL levels and increased biliary cholesterol excretion, and indicates that ABCG1 can modulate plasma lipoprotein levels in vivo. ABCG1 and the other ABC transporters might play an important role in cholesterol homeostasis, especially in the liver.