TY - JOUR
T1 - A novel pathway for regulation of glucose-dependent insulinotropic polypeptide (GIP) receptor expression in beta cells.
AU - Lynn, Francis C.
AU - Thompson, Stephen A.
AU - Pospisilik, J. Andrew
AU - Ehses, Jan A.
AU - Hinke, Simon A.
AU - Pamir, Nathalie
AU - McIntosh, Christopher H.S.
AU - Pederson, Raymond A.
PY - 2003/1
Y1 - 2003/1
N2 - Glucose-dependent insulinotropic polypeptide (GIP) is secreted postprandially and acts in concert with glucose to stimulate insulin secretion from the pancreas. Here, we describe a novel pathway for the regulation of GIP receptor (GIPR) expression within clonal beta-cell lines, pancreatic islets, and in vivo. High (25 mM) glucose was able to significantly reduce GIPR mRNA levels in INS(832/13) cells after only 6 h. In contrast, palmitic acid (2 mM) and WY 14643 (100 microM) stimulated approximate doublings of GIPR expression in INS(832/13) cells under low (5.5 mM), but not high (25 mM), glucose conditions, suggesting that fat can regulate GIPR expression via PPARalpha in a glucose-dependent manner. Both MK-886, an antagonist of PPARalpha, and a dominant negative form of PPARalpha transfected into INS(832/13) cells caused a significant reduction in GIPR expression in low, but not high, glucose conditions. Finally, in hyperglycemic clamped rats, there was a 70% reduction in GIPR expression in the islets and a 71% reduction in GIP-stimulated insulin secretion from the perfused pancreas. Thus, evidence is presented that the GIPR is controlled at normoglycemia by the fatty acid load on the islet; however, when exposed to hyperglycemic conditions, the GIPR is down-regulated, which may contribute to the decreased responsiveness to GIP that is observed in type 2 diabetes.
AB - Glucose-dependent insulinotropic polypeptide (GIP) is secreted postprandially and acts in concert with glucose to stimulate insulin secretion from the pancreas. Here, we describe a novel pathway for the regulation of GIP receptor (GIPR) expression within clonal beta-cell lines, pancreatic islets, and in vivo. High (25 mM) glucose was able to significantly reduce GIPR mRNA levels in INS(832/13) cells after only 6 h. In contrast, palmitic acid (2 mM) and WY 14643 (100 microM) stimulated approximate doublings of GIPR expression in INS(832/13) cells under low (5.5 mM), but not high (25 mM), glucose conditions, suggesting that fat can regulate GIPR expression via PPARalpha in a glucose-dependent manner. Both MK-886, an antagonist of PPARalpha, and a dominant negative form of PPARalpha transfected into INS(832/13) cells caused a significant reduction in GIPR expression in low, but not high, glucose conditions. Finally, in hyperglycemic clamped rats, there was a 70% reduction in GIPR expression in the islets and a 71% reduction in GIP-stimulated insulin secretion from the perfused pancreas. Thus, evidence is presented that the GIPR is controlled at normoglycemia by the fatty acid load on the islet; however, when exposed to hyperglycemic conditions, the GIPR is down-regulated, which may contribute to the decreased responsiveness to GIP that is observed in type 2 diabetes.
UR - http://www.scopus.com/inward/record.url?scp=0037268159&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0037268159&partnerID=8YFLogxK
U2 - 10.1096/fj.02-0243fje
DO - 10.1096/fj.02-0243fje
M3 - Article
C2 - 12475913
AN - SCOPUS:0037268159
SN - 0892-6638
VL - 17
SP - 91
EP - 93
JO - The FASEB journal : official publication of the Federation of American Societies for Experimental Biology
JF - The FASEB journal : official publication of the Federation of American Societies for Experimental Biology
IS - 1
ER -