Upregulation of β-cell genes and improved function in rodent islets following chronic glucokinase activation

J Mol Endocrinol. 2011 Jul 18;47(1):59-67. doi: 10.1530/JME-10-0157. Print 2011 Aug.

Abstract

Glucokinase (GK) plays a critical role in controlling blood glucose; GK activators have been shown to stimulate insulin secretion acutely both in vitro and in vivo. Sustained stimulation of insulin secretion could potentially lead to β-cell exhaustion; this study examines the effect of chronic GK activation on β-cells. Gene expression and insulin secretion were measured in rodent islets treated in vitro with GKA71 for 72 h. Key β-cell gene expression was measured in rat, mouse and global GK heterozygous knockout mouse islets (gk(del/wt)). Insulin secretion, after chronic exposure to GKA71, was measured in perifused rat islets. GKA71 acutely increased insulin secretion in rat islets in a glucose-dependent manner. Chronic culture of mouse islets with GKA71 in 5 mmol/l glucose significantly increased the expression of insulin, IAPP, GLUT2, PDX1 and PC1 and decreased the expression of C/EBPβ compared with 5 mmol/l glucose alone. Similar increases were shown for insulin, GLUT2, IAPP and PC1 in chronically treated rat islets. Insulin mRNA was also increased in GKA71-treated gk(del/wt) islets. No changes in GK mRNA were observed. Glucose-stimulated insulin secretion was improved in perifused rat islets following chronic treatment with GKA71. This was associated with a greater insulin content and GK protein level. Chronic treatment of rodent islets with GKA71 showed an upregulation of key β-cell genes including insulin and an increase in insulin content and GK protein compared with glucose alone.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Enzyme Activation / drug effects*
  • Enzyme Activators / pharmacology*
  • Enzyme Assays
  • Glucokinase / chemistry
  • Glucokinase / metabolism*
  • Glucose / metabolism
  • Insulin / genetics
  • Insulin / metabolism
  • Insulin Secretion
  • Insulin-Secreting Cells / drug effects
  • Insulin-Secreting Cells / metabolism
  • Insulin-Secreting Cells / physiology*
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Rats
  • Rats, Wistar
  • Sulfones / pharmacology*
  • Thiadiazoles / pharmacology*
  • Tissue Culture Techniques
  • Transcription, Genetic / drug effects
  • Up-Regulation / genetics*

Substances

  • 3-(2-methoxy-1-methylethoxy)-5-(4-methylsulfonylphenoxy)-N-(3-methyl-1,2,4-thiadiazol-5-yl)benzamide
  • Enzyme Activators
  • Insulin
  • Sulfones
  • Thiadiazoles
  • Glucokinase
  • Glucose