title: Role of UBIAD1 in Intracellular Cholesterol Metabolism and Vascular Cell Calcification.
abstract: Vascular calcification is an important risk factor associated with mortality among patients with chronic kidney disease. Intracellular cholesterol metabolism is involved in the process of vascular cell calcification. In this study, we investigated the role of UbiA prenyltransferase domain containing 1 (UBIAD1) in intracellular cholesterol metabolism and vascular cell calcification, and identified its subcellular location. Primary human umbilical vein smooth muscle cells (HUVSMCs) were incubated with either growth medium (1.4 mmol/L Pi) or calcification medium (CM) (3.0 mmol/L Pi). Under treatment with CM, HUVSMCs were further incubated with exogenous cholesterol, or menaquinone-4, a product of UBIAD1. The plasmid and small interfering RNA were transfected in HUVSMCs to alter the expression of UBIAD1. Matrix calcium quantitation, alkaline phosphatase activity, intracellular cholesterol level and menaquinone-4 level were measured. The expression of several genes involved in cholesterol metabolism were analyzed. Using an anti-UBIAD1 antibody, an endoplasmic reticulum marker and a Golgi marker, the subcellular location of UBIAD1 in HUVSMCs was analyzed. CM increased matrix calcium, alkaline phosphatase activity and intracellular cholesterol level, and reduced UBIAD1 expression and menaquinone-4 level. Addition of cholesterol contributed to increased matrix calcification and alkaline phosphatase activity in a dose-dependent manner. Elevated expression of UBIAD1 or menaquinone-4 in HUVSMCs treated with CM significantly reduced intracellular cholesterol level, matrix calcification and alkaline phosphatase activity, but increased menaquinone-4 level. Elevated expression of UBIAD1 or menaquinone-4 reduced the gene expression of sterol regulatory element-binding protein-2, and increased gene expression of ATP binding cassette transporters A1, which are in charge of cholesterol synthesis and efflux. UBIAD1 co-localized with the endoplasmic reticulum marker and the Golgi marker in HUVSMCs. In conclusion, high intracellular cholesterol content contributes to phosphate-induced vascular cell differentiation and calcification. UBIAD1 or menaquinone-4 could decrease vascular cell differentiation and calcification, probably via its potent role of inversely modulating cellular cholesterol.
authors.affiliation: Department of Nephrology, Beijing Friendship Hospital, Faculty of Nephrology, Capital Medical University, Xicheng District, Beijing, China.
authors.forename: Sha
authors.initials: S
authors.lastname: Liu
authors.affiliation: Department of Nephrology, Beijing Friendship Hospital, Faculty of Nephrology, Capital Medical University, Xicheng District, Beijing, China.
authors.forename: Wang
authors.initials: W
authors.lastname: Guo
authors.affiliation: Department of Nephrology, Beijing Friendship Hospital, Faculty of Nephrology, Capital Medical University, Xicheng District, Beijing, China.
authors.forename: Xue
authors.initials: X
authors.lastname: Han
authors.affiliation: Department of Nephrology, Beijing Friendship Hospital, Faculty of Nephrology, Capital Medical University, Xicheng District, Beijing, China.
authors.forename: Wendi
authors.initials: W
authors.lastname: Dai
authors.affiliation: Department of Nephrology, Beijing Friendship Hospital, Faculty of Nephrology, Capital Medical University, Xicheng District, Beijing, China.
authors.forename: Zongli
authors.initials: Z
authors.lastname: Diao
authors.affiliation: Department of Nephrology, Beijing Friendship Hospital, Faculty of Nephrology, Capital Medical University, Xicheng District, Beijing, China.
authors.forename: Wenhu
authors.initials: W
authors.lastname: Liu
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D002463:Cell Membrane Permeability / Q000187:drug effects; D002784:Cholesterol / Q000378:metabolism*; D003470:Culture Media; D004122:Dimethylallyltranstransferase / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006056:Golgi Apparatus / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D042541:Intracellular Space / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism; D010006:Osteoblasts / Q000187:drug effects / Q000473:pathology; D010758:Phosphorus / Q000494:pharmacology; D014471:Umbilical Veins / Q000473:pathology; D061205:Vascular Calcification / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D024482:Vitamin K 2 / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D003470:Culture Media; D024482:Vitamin K 2; C030814:menatetrenone; D010758:Phosphorus; D002784:Cholesterol; D004122:Dimethylallyltranstransferase; C425464:UBIAD1 protein, human; D000469:Alkaline Phosphatase