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Leif Groop

Leif Groop

Principal investigator

Leif Groop

Differential phosphorylation of Janus kinase 2, Stat5A and Stat5B in response to growth hormone in primary rat adipocytes

Author

  • Martin Ridderstråle
  • Leif Groop

Summary, in English

In vitro growth hormone (GH) stimulation of Janus kinase 2 (Jak2) tyrosine phosphorylation and activation has been detected in rat adipocytes where GH exerts both chronic diabetogenic and acute insulin-like effects but not in adipocytes where only chronic diabetogenic effects are exerted. The 95 kDa transcription factor Stat5, which is tyrosine phosphorylated in response to GH in both cases, is here identified as the 5A-isoform. Stat5B was not tyrosine phosphorylated in response to GH in adipocytes but subject to a gel supershift indicating regulation by serine and/or threonine phosphorylation. The differential tyrosine phosphorylation of these proteins suggests involvement of a kinase other than Jak2 in Stat5A activation. However, in adipocytes where GH exerts both diabetogenic and insulin-like effects, and both Jak2 and Stat5A were activated, their phosphorylation kinetics and downregulation of tyrosine phosphorylation were almost identical. We conclude that Stat5A is important for the diabetogenic actions of GH and that Jak2 still is the most probable candidate kinase for Stat5A in primary adipocytes.

Department/s

  • Diabetes - Clinical Obesity
  • Genomics, Diabetes and Endocrinology

Publishing year

2001

Language

English

Pages

49-54

Publication/Series

Molecular and Cellular Endocrinology

Volume

183

Issue

1-2

Document type

Journal article

Publisher

Elsevier

Topic

  • Endocrinology and Diabetes

Keywords

  • Growth hormone (GH)
  • Janus kinase 2 (Jak2)
  • Signal transducer and activator of transcription (Stat)
  • Protein phosphorylation
  • Lipolysis
  • Rat adipocyte

Status

Published

Research group

  • Diabetes - Clinical Obesity
  • Genomics, Diabetes and Endocrinology

ISBN/ISSN/Other

  • ISSN: 1872-8057