Facilitative glucose transporter 9 expression affects glucose sensing in pancreatic beta-cells. Endocrinology 2009 Dec;150(12):5302-10
Date
10/08/2009Pubmed ID
19808778Pubmed Central ID
PMC2795723DOI
10.1210/en.2009-0747Scopus ID
2-s2.0-71949104919 (requires institutional sign-in at Scopus site) 46 CitationsAbstract
Facilitative glucose transporters (GLUTs) including GLUT9, accelerate the facilitative diffusion of glucose across the plasma membrane. Studies in GLUT2-deficient mice suggested the existence of another GLUT in the mammalian beta-cell responsible for glucose sensing. The objective of this study was to determine the expression and function of GLUT9 in murine and human beta-cells. mRNA and protein expression levels were determined for both isoforms of GLUT9 in murine and human isolated islets as well as insulinoma cell lines (MIN6). Immunohistochemistry and subcellular localization were performed to localize the protein within the cell. Small interfering RNA knockdown of GLUT9 was used to determine the effect of this transporter, in the presence of GLUT2, on cell metabolism and insulin secretion in MIN6 and INS cells. In this report we demonstrate that GLUT9a and GLUT9b are expressed in pancreatic islets and that this expression localizes to insulin-containing beta-cells. Subcellular localization studies indicate that mGLUT9b is found associated with the plasma membrane as well as in the high-density microsome fraction and low-density microsome fraction, whereas mGLUT9a appears to be located only in the high-density microsome and low-density microsome under basal conditions. Functionally GLUT9 appears to participate in the regulation of glucose-stimulated insulin secretion in addition to GLUT2. small interfering RNA knockdown of GLUT9 results in reduced cellular ATP levels that correlate with reductions in glucose-stimulated insulin secretion in MIN6 and INS cells. These studies confirm the expression of GLUT9a and GLUT9b in murine and human beta-cells and suggest that GLUT9 may participate in glucose-sensing in beta-cells.
Author List
Evans SA, Doblado M, Chi MM, Corbett JA, Moley KHAuthor
John A. Corbett PhD Chair, Professor in the Biochemistry department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
AnimalsBlotting, Western
Cell Line, Tumor
Cell Membrane
Gene Expression
Glucose
Glucose Transport Proteins, Facilitative
Humans
Immunohistochemistry
Insulin
Insulin-Secreting Cells
Mice
Mice, Inbred C57BL
Microsomes
RNA, Small Interfering
Reverse Transcriptase Polymerase Chain Reaction
Transfection
