Calcium-mobilizing insulin secretagogues stimulate transcription that is directed by the cyclic adenosine 3',5'-monophosphate/calcium response element in a pancreatic islet beta-cell line

Endocrinology. 1996 Jan;137(1):225-33. doi: 10.1210/endo.137.1.8536617.

Abstract

In pancreatic beta-cells, calcium is required for insulin secretion, but can also stimulate gene transcription. High potassium-induced membrane depolarization and calcium influx have previously been shown to activate kinases that phosphorylate and thereby activate the transcription factor cAMP response element (CRE-binding protein (CREB) binding to CREs. It is unknown, however, whether hormones and neurotransmitters can activate this mechanism. Arginine vasopressin (AVP), bombesin, and acetylcholine potentiate glucose-induced insulin secretion and are known to raise cytosolic calcium levels through binding to cell surface receptors that activate phospholipase C. The effect of AVP on CRE-directed transcription was examined in the beta-cell line HIT. AVP (0.1-100 nM) stimulated gene transcription after transient transfection of a reporter gene that was placed under the transcriptional control of a CRE. This effect was inhibited by a vasopressin V1 receptor antagonist and depended on calcium influx and calcineurin phosphatase activity. By immunoblots with antiphospho-CREB antibodies and by using a Gal4-CREB fusion protein, it was shown that AVP induces the phosphorylation and activation of CREB. Like AVP, bombesin (100 nM) and the muscarinic agonist carbachol (200 microM) stimulated CRE-mediated transcription. These results show that calcium-mediating insulin secretagogues can activate CREB/CRE-directed transcription in HIT cells, offering a mechanism by which these secretagogues could produce long term effects on beta-cell function, changing the pattern of gene expression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Arginine Vasopressin / pharmacology
  • Biological Transport
  • Calcium / metabolism*
  • Calcium / physiology
  • Cell Line
  • Cricetinae
  • Cyclic AMP Response Element-Binding Protein / physiology*
  • Cyclosporine / pharmacology
  • Insulin / metabolism*
  • Insulin Secretion
  • Islets of Langerhans / cytology
  • Islets of Langerhans / physiology*
  • Phosphorylation / drug effects
  • Tacrolimus / pharmacology
  • Transcription, Genetic* / drug effects

Substances

  • Cyclic AMP Response Element-Binding Protein
  • Insulin
  • Arginine Vasopressin
  • Cyclosporine
  • Calcium
  • Tacrolimus