Abstract
Phospholipid transfer protein (PLTP) plays an important role in human plasma HDL metabolism. Clinical data have recently indicated that plasma PLTP activity and mass were both higher in diabetic patients concomitant with hyperglycemia. The present study shows that high glucose increases both PLTP mRNA and functional activity in HepG2 cells, due to a significant increase in the promoter activity of human PLTP gene. The glucose-responsive elements are located between -759 and -230 of the PLTP 5'-flanking region, within which two binding motifs (-537 to -524 and -339 to -327) for either peroxisome proliferator-activated receptor or farnesoid X-activated receptor are involved in this glucose-mediated transcriptional regulation. This finding suggests that high glucose upregulates the transcription of human PLTP gene via nuclear hormone receptors. In addition, high glucose increases mRNA levels for several genes that are functionally important in HDL metabolism, including human ATP-binding cassette transporter A1, apolipoprotein A-I, scavenger receptor BI, and hepatic lipase. The functional promoter activities of these genes are enhanced by high glucose in three cell lines tested, indicating that glucose may also regulate these genes at the transcriptional level. Our findings provide a molecular basis for a role of hyperglycemia in altered HDL metabolism.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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ATP-Binding Cassette Transporters / genetics
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Apolipoprotein A-I / genetics
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Apolipoprotein A-II / genetics
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Carcinoma, Hepatocellular
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Carrier Proteins / genetics*
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DNA-Binding Proteins / metabolism
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Gene Expression Regulation / drug effects
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Gene Expression Regulation / physiology*
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Glucose / pharmacology*
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Humans
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Lipase / genetics
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Lipoproteins, HDL / metabolism*
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Liver Neoplasms
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Membrane Proteins / genetics*
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Phospholipid Transfer Proteins*
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Promoter Regions, Genetic*
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RNA, Messenger / genetics
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RNA, Messenger / metabolism
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Receptors, Cytoplasmic and Nuclear / metabolism*
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Receptors, Immunologic / genetics
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Receptors, Lipoprotein*
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Receptors, Scavenger
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Reverse Transcriptase Polymerase Chain Reaction
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Scavenger Receptors, Class B
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Transcription Factors / metabolism*
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Transcription, Genetic / drug effects
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Transcription, Genetic / physiology*
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Tumor Cells, Cultured
Substances
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ATP-Binding Cassette Transporters
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Apolipoprotein A-I
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Apolipoprotein A-II
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Carrier Proteins
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DNA-Binding Proteins
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Lipoproteins, HDL
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Membrane Proteins
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Phospholipid Transfer Proteins
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RNA, Messenger
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Receptors, Cytoplasmic and Nuclear
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Receptors, Immunologic
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Receptors, Lipoprotein
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Receptors, Scavenger
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Scarb1 protein, mouse
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Scavenger Receptors, Class B
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Transcription Factors
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farnesoid X-activated receptor
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Lipase
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Glucose