Overexpression of sterol carrier protein-2 differentially alters hepatic cholesterol accumulation in cholesterol-fed mice

J Lipid Res. 2009 Jul;50(7):1429-47. doi: 10.1194/jlr.M900020-JLR200. Epub 2009 Mar 16.

Abstract

Although in vitro studies suggest a role for sterol carrier protein-2 (SCP-2) in cholesterol trafficking and metabolism, the physiological significance of these observations remains unclear. This issue was addressed by examining the response of mice overexpressing physiologically relevant levels of SCP-2 to a cholesterol-rich diet. While neither SCP-2 overexpression nor cholesterol-rich diet altered food consumption, increased weight gain, hepatic lipid, and bile acid accumulation were observed in wild-type mice fed the cholesterol-rich diet. SCP-2 overexpression further exacerbated hepatic lipid accumulation in cholesterol-fed females (cholesterol/cholesteryl esters) and males (cholesterol/cholesteryl esters and triacyglycerol). Primarily in female mice, hepatic cholesterol accumulation induced by SCP-2 overexpression was associated with increased levels of LDL-receptor, HDL-receptor scavenger receptor-B1 (SR-B1) (as well as PDZK1 and/or membrane-associated protein 17 kDa), SCP-2, liver fatty acid binding protein (L-FABP), and 3alpha-hydroxysteroid dehydrogenase, without alteration of other proteins involved in cholesterol uptake (caveolin), esterification (ACAT2), efflux (ATP binding cassette A-1 receptor, ABCG5/8, and apolipoprotein A1), or oxidation/transport of bile salts (cholesterol 7alpha-hydroxylase, sterol 27alpha-hydroxylase, Na(+)/taurocholate cotransporter, Oatp1a1, and Oatp1a4). The effects of SCP-2 overexpression and cholesterol-rich diet was downregulation of proteins involved in cholesterol transport (L-FABP and SR-B1), cholesterol synthesis (related to sterol regulatory element binding protein 2 and HMG-CoA reductase), and bile acid oxidation/transport (via Oapt1a1, Oatp1a4, and SCP-x). Levels of serum and hepatic bile acids were decreased in cholesterol-fed SCP-2 overexpression mice, especially in females, while the total bile acid pool was minimally affected. Taken together, these findings support an important role for SCP-2 in hepatic cholesterol homeostasis.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • ATP-Binding Cassette Transporters / genetics
  • ATP-Binding Cassette Transporters / metabolism
  • Animals
  • Bile Acids and Salts / blood
  • Bile Acids and Salts / metabolism
  • Body Weight
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Caveolin 1 / genetics
  • Caveolin 1 / metabolism
  • Cholestanetriol 26-Monooxygenase / genetics
  • Cholestanetriol 26-Monooxygenase / metabolism
  • Cholesterol 7-alpha-Hydroxylase / genetics
  • Cholesterol 7-alpha-Hydroxylase / metabolism
  • Cholesterol* / administration & dosage
  • Cholesterol* / metabolism
  • Cholesterol, Dietary*
  • Fatty Acid-Binding Proteins / genetics
  • Fatty Acid-Binding Proteins / metabolism
  • Female
  • Humans
  • Lipid Metabolism
  • Lipids / chemistry
  • Liver / anatomy & histology
  • Liver / metabolism*
  • Male
  • Mice
  • Mice, Transgenic
  • Organ Size
  • Organic Anion Transporters / genetics
  • Organic Anion Transporters / metabolism
  • Phenotype
  • Phospholipids / blood
  • Scavenger Receptors, Class B / genetics
  • Scavenger Receptors, Class B / metabolism
  • Tissue Distribution

Substances

  • ATP-Binding Cassette Transporters
  • Bile Acids and Salts
  • Carrier Proteins
  • Caveolin 1
  • Cholesterol, Dietary
  • Fabp1 protein, mouse
  • Fatty Acid-Binding Proteins
  • Lipids
  • Organic Anion Transporters
  • Phospholipids
  • Scarb1 protein, mouse
  • Scavenger Receptors, Class B
  • sterol carrier proteins
  • Cholesterol
  • Cholesterol 7-alpha-Hydroxylase
  • Cyp7a1 protein, mouse
  • Cholestanetriol 26-Monooxygenase
  • Cyp27a1 protein, mouse