Pyk2 cytonuclear localization: mechanisms and regulation by serine dephosphorylation.
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.
Inserm, UMR-S 839, Institut du Fer à Moulin, 17 rue du Fer à Moulin, 75005, Paris, France.
Camille
C
Faure
Mariana
M
Ramos
Jean-Antoine
JA
Girault
D021581:Active Transport, Cell Nucleus; D020816:Amino Acid Motifs; D000818:Animals; D019703:Calcineurin / Q000502:physiology; D002467:Cell Nucleus / Q000201:enzymology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism / Q000502:physiology; D051418:Focal Adhesion Kinase 2 / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000032:analysis / Q000378:metabolism; D049790:Nuclear Export Signals; D019913:Nuclear Localization Signals; D016716:PC12 Cells; D010766:Phosphorylation; D020033:Protein Isoforms / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D019154:Protein Splicing; D021381:Protein Transport; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000032:analysis / Q000378:metabolism; D012694:Serine / Q000378:metabolism
D049790:Nuclear Export Signals; D019913:Nuclear Localization Signals; D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D012694:Serine; D051418:Focal Adhesion Kinase 2; D017868:Cyclic AMP-Dependent Protein Kinases; D019703:Calcineurin