Dominant negative variants of the SHP-2 tyrosine phosphatase inhibit prolactin activation of Jak2 (janus kinase 2) and induction of Stat5 (signal transducer and activator of transcription 5)-dependent transcription

Mol Endocrinol. 1998 Apr;12(4):556-67. doi: 10.1210/mend.12.4.0086.

Abstract

PRL plays a central role in the regulation of milk protein gene expression in mammary epithelial cells and in the growth and differentiation of lymphocytes. It confers its activity through binding to a specific transmembrane, class I hematopoietic receptor. Ligand binding leads to receptor dimerization and activation of the tyrosine kinase Jak (janus kinase) 2, associated with the membrane-proximal, intracellular domain of the receptor. Jak2 phosphorylates and activates Stat5, a member of the Stat (signal transducers and activators of transcription) family. PRL receptor also activates SHP-2, a cytosolic tyrosine phosphatase. We investigated the connection between these two signaling events and derived a dominant negative mutant of SHP-2 comprising the two SH2 domains [SHP-2(SH2)2]. An analogous variant of the SHP-1 phosphatase [SHP-1(SH2)2] was used as a control. The dominant negative mutant of SHP-2 was found to inhibit the induction of tyrosine phosphorylation and DNA-binding activity of m-Stat5a, m-Stat5b, and the carboxyl-terminal deletion variant m-Stat5adelta749, as well as the transactivation potential of m-Stat5a and m-Stat5b. The dominant negative mutant SHP-1(SH2)2 had no effect. The kinase activity of Jak2 is also dependent on a functional SHP-2 phosphatase. We propose that SHP-2 relieves an inhibitory tyrosine phosphorylation event in Jak2 required for Jak2 activity, Stat5 phosphorylation, and transcriptional induction.

MeSH terms

  • Animals
  • COS Cells
  • Caseins / drug effects
  • Caseins / genetics
  • DNA-Binding Proteins / antagonists & inhibitors*
  • DNA-Binding Proteins / biosynthesis
  • DNA-Binding Proteins / genetics
  • Enzyme Activation / drug effects
  • Genes, Dominant
  • Humans
  • Intracellular Signaling Peptides and Proteins
  • Janus Kinase 2
  • Jurkat Cells
  • Milk Proteins*
  • Mutagenesis, Site-Directed
  • Phosphorylation
  • Prolactin / antagonists & inhibitors
  • Prolactin / pharmacology*
  • Promoter Regions, Genetic / drug effects
  • Protein Tyrosine Phosphatase, Non-Receptor Type 11
  • Protein Tyrosine Phosphatase, Non-Receptor Type 6
  • Protein Tyrosine Phosphatases / genetics*
  • Protein Tyrosine Phosphatases / metabolism
  • Protein Tyrosine Phosphatases / physiology*
  • Protein-Tyrosine Kinases / antagonists & inhibitors*
  • Protein-Tyrosine Kinases / metabolism
  • Proto-Oncogene Proteins*
  • Receptors, Prolactin / metabolism
  • STAT5 Transcription Factor
  • Sequence Deletion
  • Trans-Activators / antagonists & inhibitors*
  • Trans-Activators / biosynthesis
  • Trans-Activators / genetics
  • Transcription, Genetic* / drug effects
  • Transcriptional Activation / drug effects
  • Transcriptional Activation / genetics
  • Tumor Suppressor Proteins
  • Tyrosine / metabolism

Substances

  • Caseins
  • DNA-Binding Proteins
  • Intracellular Signaling Peptides and Proteins
  • Milk Proteins
  • Proto-Oncogene Proteins
  • Receptors, Prolactin
  • STAT5 Transcription Factor
  • STAT5A protein, human
  • STAT5B protein, human
  • Trans-Activators
  • Tumor Suppressor Proteins
  • Tyrosine
  • Prolactin
  • Protein-Tyrosine Kinases
  • JAK2 protein, human
  • Janus Kinase 2
  • PTPN11 protein, human
  • PTPN6 protein, human
  • Protein Tyrosine Phosphatase, Non-Receptor Type 11
  • Protein Tyrosine Phosphatase, Non-Receptor Type 6
  • Protein Tyrosine Phosphatases