Abstract
As glucose is known to induce insulin secretion in pancreatic Beta cells, this study investigated the role of a phospholipase D (PLD)-related signaling pathway in insulin secretion caused by high glucose in the pancreatic Beta-cell line MIN6N8. It was found that the PLD activity and PLD1 expression were both increased by high glucose (33.3 mM) treatment. The dominant negative PLD1 inhibited glucose-induced Beta2 expression, and glucose-induced insulin secretion was blocked by treatment with 1-butanol or PLD1-siRNA. These results suggest that high glucose increased insulin secretion through a PLD1-related pathway. High glucose induced the binding of Arf6 to PLD1. Pretreatment with brefeldin A (BFA), an Arf inhibitor, decreased the PLD activity as well as the insulin secretion. Furthermore, BFA blocked the glucose-induced mTOR and p70S6K activation, while mTOR inhibition with rapamycin attenuated the glucose induced Beta2 expression and insulin secretion. Thus, when taken together, PLD1 would appear to be an important regulator of glucose-induced insulin secretion through an Arf6/PLD1/mTOR/p70S6K/ Beta2 pathway in MIN6N8 cells.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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ADP-Ribosylation Factor 6
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ADP-Ribosylation Factors / metabolism
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ADP-Ribosylation Factors / physiology
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Animals
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Basic Helix-Loop-Helix Transcription Factors / metabolism
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Basic Helix-Loop-Helix Transcription Factors / physiology
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Cells, Cultured
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Gene Expression Regulation, Enzymologic / drug effects
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Glucose / pharmacology*
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Insulin / metabolism*
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Insulin Secretion
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Insulin-Secreting Cells / drug effects*
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Insulin-Secreting Cells / enzymology
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Insulin-Secreting Cells / metabolism
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Intracellular Signaling Peptides and Proteins / metabolism
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Intracellular Signaling Peptides and Proteins / physiology
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Mice
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Models, Biological
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Oligodeoxyribonucleotides, Antisense / pharmacology
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Phospholipase D / antagonists & inhibitors
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Phospholipase D / genetics
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Phospholipase D / metabolism
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Phospholipase D / physiology*
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Protein Serine-Threonine Kinases / metabolism
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Protein Serine-Threonine Kinases / physiology
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Ribosomal Protein S6 Kinases, 70-kDa / metabolism
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Ribosomal Protein S6 Kinases, 70-kDa / physiology
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Signal Transduction / drug effects
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Signal Transduction / genetics
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TOR Serine-Threonine Kinases
Substances
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ADP-Ribosylation Factor 6
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Basic Helix-Loop-Helix Transcription Factors
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Insulin
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Intracellular Signaling Peptides and Proteins
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Oligodeoxyribonucleotides, Antisense
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mTOR protein, mouse
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Protein Serine-Threonine Kinases
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Ribosomal Protein S6 Kinases, 70-kDa
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TOR Serine-Threonine Kinases
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Phospholipase D
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phospholipase D1
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ADP-Ribosylation Factors
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Arf6 protein, mouse
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Glucose