Attenuation of insulin secretion by insulin-like growth factor 1 is mediated through activation of phosphodiesterase 3B

Proc Natl Acad Sci U S A. 1997 Apr 1;94(7):3223-8. doi: 10.1073/pnas.94.7.3223.

Abstract

Both insulin and insulin-like growth factor 1 (IGF-1) are known to reduce glucose-dependent insulin secretion from the beta cells of pancreatic islets. In this paper we show that the mechanism by which IGF-1 mediates this effect is in large part through activation of a specific cyclic nucleotide phosphodiesterase, phosphodiesterase 3B (PDE3B). More specifically, in both isolated pancreatic islets and insulin-secreting HIT-T15 cells, IGF-1 inhibits insulin secretion that has been increased by glucose and glucagonlike peptide 1 (GLP-1). Moreover, IGF-1 decreases cAMP levels in parallel to the reduction of insulin secretion. Insulin secretion stimulated by cAMP analogs that activate protein kinase A and also are substrates for PDE3B is also inhibited by IGF-1. However, IGF-1 does not inhibit insulin secretion stimulated by nonhydrolyzable cAMP analogs. In addition, selective inhibitors of PDE3B completely block the ability of IGF-1 to inhibit insulin secretion. Finally, PDE3B activity measured in vitro after immunoprecipitation from cells treated with IGF-1 is higher than the activity from control cells. Taken together with the fact that pancreatic beta cells express little or no insulin receptor but large amounts of IGF-1 receptor, these data strongly suggest a new regulatory feedback loop model for the control of insulin secretion. In this model, increased insulin secretion in vivo will stimulate IGF-1 synthesis by the liver, and the secreted IGF-1 in turn feedback inhibits insulin secretion from the beta cells through an IGF-1 receptor-mediated pathway. This pathway is likely to be particularly important when levels of both glucose and secretagogues such as GLP-1 are elevated.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cell Line
  • Cyclic AMP / metabolism
  • Enzyme Activation
  • Insulin / metabolism*
  • Insulin Secretion
  • Insulin-Like Growth Factor I / physiology*
  • Islets of Langerhans / drug effects
  • Islets of Langerhans / enzymology
  • Islets of Langerhans / metabolism
  • Mice
  • Molecular Sequence Data
  • Phosphodiesterase Inhibitors / pharmacology
  • Phosphoric Diester Hydrolases / metabolism*
  • Receptor, IGF Type 1 / metabolism

Substances

  • Insulin
  • Phosphodiesterase Inhibitors
  • Insulin-Like Growth Factor I
  • Cyclic AMP
  • Receptor, IGF Type 1
  • Phosphoric Diester Hydrolases

Associated data

  • GENBANK/X95521