Activation of cJun NH2-terminal kinase/stress-activated protein kinase by insulin

Biochemistry. 1996 Jul 2;35(26):8769-75. doi: 10.1021/bi952651r.

Abstract

One of insulin's many biological effects is the increased transcription of AP-1-regulated genes. cJun is the principal component of the AP-1 transcription complex, which is regulated by the newly discovered members of the MAPK superfamily referred to as cJun NH2-terminal kinases (JNKs) or stress-activated protein kinases (SAPKs). We show that insulin stimulates a dose- and time-dependent increase in JNK activity in Rat 1 fibroblasts overexpressing human insulin receptors (Rat 1 HIR cells). Using two different polyclonal anti-JNK antibodies, JNK activity was measured after immunoprecipitation from whole cell extracts by phosphorylation of GSTcJun(1-79). Peak activation occurred 15 min after insulin addition, resulting in a 2.5-fold increase in GSTcJun(1-79) phosphorylation over unstimulated controls. Maximal JNK activation correlated with the onset of AP-1 DNA binding activity. Both insulin-stimulated JNK activity and insulin-induced AP-1 transcriptional activity were found to be Ras-dependent. These data suggest that in Rat 1 cells, JNK activation may play a role in insulin-regulated AP-1 transcriptional activity leading to a mitogenic response.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Calcium-Calmodulin-Dependent Protein Kinases / metabolism*
  • DNA Probes
  • Enzyme Activation
  • Humans
  • Insulin / pharmacology*
  • JNK Mitogen-Activated Protein Kinases
  • Mitogen-Activated Protein Kinases*
  • Molecular Sequence Data
  • Phosphorylation
  • Proto-Oncogene Proteins c-jun / genetics
  • Proto-Oncogene Proteins c-jun / metabolism
  • RNA, Messenger / genetics
  • Rats
  • Receptor, Insulin / genetics
  • Sequence Homology, Amino Acid
  • Transcription, Genetic

Substances

  • DNA Probes
  • Insulin
  • Proto-Oncogene Proteins c-jun
  • RNA, Messenger
  • Receptor, Insulin
  • Calcium-Calmodulin-Dependent Protein Kinases
  • JNK Mitogen-Activated Protein Kinases
  • Mitogen-Activated Protein Kinases