Activation of phosphatidylinositol 3-kinase contributes to insulin-like growth factor I-mediated inhibition of pancreatic β-cell death

L. I.U. Wenli, Catherine Chin-Chance, L. E.E. Eun-Jig, William L. Lowe

Research output: Contribution to journalArticle

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Abstract

To begin to determine whether IGF-I treatment represents a potential means of enhancing the survival of islet cell grafts after transplantation, the present studies established a model of β-cell death secondary to loss of trophic support and examined the ability of IGF-I to prevent cell death. The studies were performed using the rat pancreatic β-cell line, INS-1. Incubating INS-1 cells in RPMI 1640 and 0.25% BSA for 48 h increased cell death, as determined by lactate dehydrogenase release, compared with that of cells maintained in RPMI and 10% fetal calf serum. Addition of 100 ng/ml IGF-I to the serumfree medium decreased lactate dehydrogenase release to a level comparable to that found in cells maintained in fetal calf serum. Similar results were seen using a mouse β-cell line, MIN6, infected with an adenovirus expressing IGF-I. Examination of IGF-I-stimulated signaling demonstrated that IGF-I increased the phosphorylation of protein kinase B in both cell lines, whereas IGF-I-induced phosphorylation of the MAPKs, ERK1 and -2, was observed only in INS-1 cells. The effect of IGF-I on phosphorylation of substrates of phosphatidylinositol 3-kinase (PI 3-kinase) or protein kinase B was also examined in INS-1 cells. IGF-I increased the phosphorylation of glycogen synthase kinase 3β, BAD, FKHR, and p70S6 kinase. Another pathway that has been shown to mediate the protective of IGF-I in some cell types is activation of cAMP response element-binding protein (CREB). IGF-I increased CREB phosphorylation at a concentration as low as 10 ng/ml, and this effect was inhibited by H89, a PKA inhibitor, and PD98059, a MAPK kinase inhibitor. Consistent with the effect of IGF-I on CREB phosphorylation, IGF-I increased the transcriptional activity of CREB, although it had no effect on CREB binding to DNA. Use of inhibitors of the PI3-kinase (LY 294002) or ERK (PD98059) pathways or CREB phosphorylation (H89) in the cell death assay demonstrated partial abrogation of the protective effect of IGF-I with LY 294002. These data demonstrate that IGF-I protects pancreatic β-cells from cell death secondary to loss of trophic support and that, although IGF-I activates several signaling pathways that contribute to its protective effect in other cell types, only activation of PI 3-kinase contributes to this effect in β-cells.

Original languageEnglish
Pages (from-to)3802-3812
Number of pages11
JournalEndocrinology
Volume143
Issue number10
DOIs
Publication statusPublished - 2002 Oct 1

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Phosphatidylinositol 3-Kinase
Insulin-Like Growth Factor I
Cell Death
Cyclic AMP Response Element-Binding Protein
Phosphorylation
Proto-Oncogene Proteins c-akt
2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one
L-Lactate Dehydrogenase
Cell Line
Glycogen Synthase Kinase 3
MAP Kinase Signaling System

All Science Journal Classification (ASJC) codes

  • Endocrinology

Cite this

@article{efea73dce87049b1ba50b867311771e5,
title = "Activation of phosphatidylinositol 3-kinase contributes to insulin-like growth factor I-mediated inhibition of pancreatic β-cell death",
abstract = "To begin to determine whether IGF-I treatment represents a potential means of enhancing the survival of islet cell grafts after transplantation, the present studies established a model of β-cell death secondary to loss of trophic support and examined the ability of IGF-I to prevent cell death. The studies were performed using the rat pancreatic β-cell line, INS-1. Incubating INS-1 cells in RPMI 1640 and 0.25{\%} BSA for 48 h increased cell death, as determined by lactate dehydrogenase release, compared with that of cells maintained in RPMI and 10{\%} fetal calf serum. Addition of 100 ng/ml IGF-I to the serumfree medium decreased lactate dehydrogenase release to a level comparable to that found in cells maintained in fetal calf serum. Similar results were seen using a mouse β-cell line, MIN6, infected with an adenovirus expressing IGF-I. Examination of IGF-I-stimulated signaling demonstrated that IGF-I increased the phosphorylation of protein kinase B in both cell lines, whereas IGF-I-induced phosphorylation of the MAPKs, ERK1 and -2, was observed only in INS-1 cells. The effect of IGF-I on phosphorylation of substrates of phosphatidylinositol 3-kinase (PI 3-kinase) or protein kinase B was also examined in INS-1 cells. IGF-I increased the phosphorylation of glycogen synthase kinase 3β, BAD, FKHR, and p70S6 kinase. Another pathway that has been shown to mediate the protective of IGF-I in some cell types is activation of cAMP response element-binding protein (CREB). IGF-I increased CREB phosphorylation at a concentration as low as 10 ng/ml, and this effect was inhibited by H89, a PKA inhibitor, and PD98059, a MAPK kinase inhibitor. Consistent with the effect of IGF-I on CREB phosphorylation, IGF-I increased the transcriptional activity of CREB, although it had no effect on CREB binding to DNA. Use of inhibitors of the PI3-kinase (LY 294002) or ERK (PD98059) pathways or CREB phosphorylation (H89) in the cell death assay demonstrated partial abrogation of the protective effect of IGF-I with LY 294002. These data demonstrate that IGF-I protects pancreatic β-cells from cell death secondary to loss of trophic support and that, although IGF-I activates several signaling pathways that contribute to its protective effect in other cell types, only activation of PI 3-kinase contributes to this effect in β-cells.",
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Activation of phosphatidylinositol 3-kinase contributes to insulin-like growth factor I-mediated inhibition of pancreatic β-cell death. / Wenli, L. I.U.; Chin-Chance, Catherine; Eun-Jig, L. E.E.; Lowe, William L.

In: Endocrinology, Vol. 143, No. 10, 01.10.2002, p. 3802-3812.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Activation of phosphatidylinositol 3-kinase contributes to insulin-like growth factor I-mediated inhibition of pancreatic β-cell death

AU - Wenli, L. I.U.

AU - Chin-Chance, Catherine

AU - Eun-Jig, L. E.E.

AU - Lowe, William L.

PY - 2002/10/1

Y1 - 2002/10/1

N2 - To begin to determine whether IGF-I treatment represents a potential means of enhancing the survival of islet cell grafts after transplantation, the present studies established a model of β-cell death secondary to loss of trophic support and examined the ability of IGF-I to prevent cell death. The studies were performed using the rat pancreatic β-cell line, INS-1. Incubating INS-1 cells in RPMI 1640 and 0.25% BSA for 48 h increased cell death, as determined by lactate dehydrogenase release, compared with that of cells maintained in RPMI and 10% fetal calf serum. Addition of 100 ng/ml IGF-I to the serumfree medium decreased lactate dehydrogenase release to a level comparable to that found in cells maintained in fetal calf serum. Similar results were seen using a mouse β-cell line, MIN6, infected with an adenovirus expressing IGF-I. Examination of IGF-I-stimulated signaling demonstrated that IGF-I increased the phosphorylation of protein kinase B in both cell lines, whereas IGF-I-induced phosphorylation of the MAPKs, ERK1 and -2, was observed only in INS-1 cells. The effect of IGF-I on phosphorylation of substrates of phosphatidylinositol 3-kinase (PI 3-kinase) or protein kinase B was also examined in INS-1 cells. IGF-I increased the phosphorylation of glycogen synthase kinase 3β, BAD, FKHR, and p70S6 kinase. Another pathway that has been shown to mediate the protective of IGF-I in some cell types is activation of cAMP response element-binding protein (CREB). IGF-I increased CREB phosphorylation at a concentration as low as 10 ng/ml, and this effect was inhibited by H89, a PKA inhibitor, and PD98059, a MAPK kinase inhibitor. Consistent with the effect of IGF-I on CREB phosphorylation, IGF-I increased the transcriptional activity of CREB, although it had no effect on CREB binding to DNA. Use of inhibitors of the PI3-kinase (LY 294002) or ERK (PD98059) pathways or CREB phosphorylation (H89) in the cell death assay demonstrated partial abrogation of the protective effect of IGF-I with LY 294002. These data demonstrate that IGF-I protects pancreatic β-cells from cell death secondary to loss of trophic support and that, although IGF-I activates several signaling pathways that contribute to its protective effect in other cell types, only activation of PI 3-kinase contributes to this effect in β-cells.

AB - To begin to determine whether IGF-I treatment represents a potential means of enhancing the survival of islet cell grafts after transplantation, the present studies established a model of β-cell death secondary to loss of trophic support and examined the ability of IGF-I to prevent cell death. The studies were performed using the rat pancreatic β-cell line, INS-1. Incubating INS-1 cells in RPMI 1640 and 0.25% BSA for 48 h increased cell death, as determined by lactate dehydrogenase release, compared with that of cells maintained in RPMI and 10% fetal calf serum. Addition of 100 ng/ml IGF-I to the serumfree medium decreased lactate dehydrogenase release to a level comparable to that found in cells maintained in fetal calf serum. Similar results were seen using a mouse β-cell line, MIN6, infected with an adenovirus expressing IGF-I. Examination of IGF-I-stimulated signaling demonstrated that IGF-I increased the phosphorylation of protein kinase B in both cell lines, whereas IGF-I-induced phosphorylation of the MAPKs, ERK1 and -2, was observed only in INS-1 cells. The effect of IGF-I on phosphorylation of substrates of phosphatidylinositol 3-kinase (PI 3-kinase) or protein kinase B was also examined in INS-1 cells. IGF-I increased the phosphorylation of glycogen synthase kinase 3β, BAD, FKHR, and p70S6 kinase. Another pathway that has been shown to mediate the protective of IGF-I in some cell types is activation of cAMP response element-binding protein (CREB). IGF-I increased CREB phosphorylation at a concentration as low as 10 ng/ml, and this effect was inhibited by H89, a PKA inhibitor, and PD98059, a MAPK kinase inhibitor. Consistent with the effect of IGF-I on CREB phosphorylation, IGF-I increased the transcriptional activity of CREB, although it had no effect on CREB binding to DNA. Use of inhibitors of the PI3-kinase (LY 294002) or ERK (PD98059) pathways or CREB phosphorylation (H89) in the cell death assay demonstrated partial abrogation of the protective effect of IGF-I with LY 294002. These data demonstrate that IGF-I protects pancreatic β-cells from cell death secondary to loss of trophic support and that, although IGF-I activates several signaling pathways that contribute to its protective effect in other cell types, only activation of PI 3-kinase contributes to this effect in β-cells.

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