文章基本信息

标题：Secretion of triacylglycerol-poor VLDL particles from McA-RH7777 cells expressing human hepatic lipase
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作者：Michelle Bamji-Mirza ; Meenakshi Sundaram ; Shumei Zhong 等
期刊名称：JLR Papers In Press
印刷版ISSN：0022-2275
电子版ISSN：1539-7262
出版年度：2011
卷号：52
期号：3
页码：540-548
DOI：10.1194/jlr.M012476
语种：English
出版社：American Society for Biochemistry and Molecular Biology
摘要：Hepatic lipase (HL) plays a role in the catabolism of apolipoprotein (apo)B-containing lipoproteins through its lipolytic and ligand-binding properties. We describe a potential intracellular role of HL in the assembly and secretion of VLDL. Transient or stable expression of HL in McA-RH7777 cells resulted in decreased (by 40%) incorporation of [³H]glycerol into cell-associated and secreted triacylglycerol (TAG) relative to control cells. However, incorporation of [³⁵S]methionine/cysteine into cell and medium apoB-100 was not decreased by HL expression. The decreased ³H-TAG synthesis/secretion in HL expressing cells was not attributable to decreased expression of genes involved in lipogenesis. Fractionation of medium revealed that the decreased [³H]TAG from HL expressing cells was mainly attributable to decreased VLDL. Expression of catalytically-inactive HL (HL_SG) (Ser-145 at the catalytic site was substituted with Gly) in the cells also resulted in decreased secretion of VLDL-[³H]TAG. Examination of lumenal contents of microsomes showed a 40% decrease in [³H]TAG associated with lumenal lipid droplets in HL or HL_SG expressing cells as compared with control. The microsomal membrane-associated [³H]TAG was decreased by 50% in HL expressing cells but not in HL_SG expressing cells. Thus, expression of HL, irrespective of its lipolytic function, impairs formation of VLDL precursor [³H]TAG in the form of lumenal lipid droplets. These results suggest that HL expression in McA-RH7777 cells result in secretion of [³H]TAG-poor VLDL.
关键词：apolipoprotein B-100 ; heparin sulfate proteoglycans ; lumenal lipid droplet ; microsomal triglyceride transfer protein ; triacylglycerol ; very low density lipoprotein