Pyk2 cytonuclear localization: mechanisms and regulation by serine dephosphorylation

Cell Mol Life Sci. 2013 Jan;70(1):137-52. doi: 10.1007/s00018-012-1075-5. Epub 2012 Jul 17.

Abstract

Cytonuclear signaling is essential for long-term alterations of cellular properties. Several pathways involving regulated nuclear accumulation of Ser/Thr kinases have been described but little is known about cytonuclear trafficking of tyrosine kinases. Proline-rich tyrosine kinase 2 (Pyk2) is a cytoplasmic non-receptor tyrosine kinase enriched in neurons and involved in functions ranging from synaptic plasticity to bone resorption, as well as in cancer. We previously showed the Ca(2+)-induced, calcineurin-dependent, nuclear localization of Pyk2. Here, we characterize the molecular mechanisms of Pyk2 cytonuclear localization in transfected PC12 cells. The 700-841 linker region of Pyk2 recapitulates its depolarization-induced nuclear accumulation. This region includes a nuclear export motif regulated by phosphorylation at residue S778, a substrate of cAMP-dependent protein kinase and calcineurin. Nuclear import is controlled by a previously identified sequence in the N-terminal domain and by a novel nuclear targeting signal in the linker region. Regulation of cytonuclear trafficking is independent of Pyk2 activity. The region regulating nuclear localization is absent from the non-neuronal shorter splice isoform of Pyk2. Our results elucidate the mechanisms of Ca(2+)-induced nuclear accumulation of Pyk2. They also suggest that Pyk2 nuclear accumulation is a novel type of signaling response that may contribute to specific long-term adaptations in neurons.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Active Transport, Cell Nucleus
  • Amino Acid Motifs
  • Animals
  • Calcineurin / physiology
  • Cell Nucleus / enzymology*
  • Cyclic AMP-Dependent Protein Kinases / metabolism
  • Cyclic AMP-Dependent Protein Kinases / physiology
  • Focal Adhesion Kinase 2 / analysis*
  • Focal Adhesion Kinase 2 / chemistry
  • Focal Adhesion Kinase 2 / metabolism*
  • Green Fluorescent Proteins / analysis
  • Green Fluorescent Proteins / metabolism
  • Nuclear Export Signals
  • Nuclear Localization Signals
  • PC12 Cells
  • Phosphorylation
  • Protein Isoforms / analysis
  • Protein Isoforms / chemistry
  • Protein Isoforms / metabolism
  • Protein Splicing
  • Protein Transport
  • Rats
  • Recombinant Fusion Proteins / analysis
  • Recombinant Fusion Proteins / metabolism
  • Serine / metabolism

Substances

  • Nuclear Export Signals
  • Nuclear Localization Signals
  • Protein Isoforms
  • Recombinant Fusion Proteins
  • Green Fluorescent Proteins
  • Serine
  • Focal Adhesion Kinase 2
  • Cyclic AMP-Dependent Protein Kinases
  • Calcineurin