Sitosterolemia: a gateway to new knowledge about cholesterol metabolism.
Sitosterolemia (OMIM 210250) is a rare, autosomal recessive lipid disorder initially described almost 30 years ago. The disease is characterized by elevated plasma levels of plant sterols due to increased intestinal absorption and reduced biliary secretion of neutral sterols. Patients with sitosterolemia are frequently hypercholesterolemic, and develop xanthomas and premature coronary heart disease (CHD). Hemolysis, arthralgias and arthritis are also frequently associated with the disorder. Recently, sitosterolemia has been revealed to be due to mutations in either of the two ATP-binding cassette (ABC) half-transporters. ABCG5 or ABCG8. These two genes are expressed almost exclusively in the liver and intestine, and are co-regulated by the nuclear hormone receptor, liver X receptor (LXR). Genetically modified mice, which express either high levels or no ABCG5 and ABCG8 have been developed. Analyses of these mice confirm that these two transporters play key roles in regulating the absorption of dietary and biliary sterols, and in mediating the excretion of neutral sterols from the liver to the bile. The elucidation of the gene defects responsible for sitosterolemia provides potential therapeutic targets for the treatment of hyperlipidemias in the general population.
Berge
Knut Erik
KE
Department of Medical Genetics, Ullevaal University Hospital, Kirkeveien 166, NO-0407 Oslo, Norway. KnutErik.Berge@ulleval.no
D000071018:ATP Binding Cassette Transporter, Subfamily G, Member 5; D000071019:ATP Binding Cassette Transporter, Subfamily G, Member 8; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D000818:Animals; D002784:Cholesterol / Q000737:chemistry / Q000378:metabolism*; D008076:Cholesterol, HDL / Q000378:metabolism; D008078:Cholesterol, LDL / Q000378:metabolism; D006801:Humans; D008074:Lipoproteins / Q000235:genetics / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000378:metabolism; D012855:Sitosterols / Q000097:blood* / Q000737:chemistry
C416945:ABCG5 protein, human; C416946:ABCG8 protein, human; D000071018:ATP Binding Cassette Transporter, Subfamily G, Member 5; D000071019:ATP Binding Cassette Transporter, Subfamily G, Member 8; D018528:ATP-Binding Cassette Transporters; D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D008074:Lipoproteins; D018160:Receptors, Cytoplasmic and Nuclear; D012855:Sitosterols; D002784:Cholesterol