title: Nuclear speckles and nucleoli targeting by PIP2-PDZ domain interactions.
abstract: PDZ (Postsynaptic density protein, Disc large, Zona occludens) domains are protein-protein interaction modules that predominate in submembranous scaffolding proteins. Recently, we showed that the PDZ domains of syntenin-1 also interact with phosphatidylinositol 4,5-bisphosphate (PIP2) and that this interaction controls the recruitment of the protein to the plasma membrane. Here we evaluate the general importance of PIP2-PDZ domain interactions. We report that most PDZ proteins bind weakly to PIP2, but that syntenin-2, the closest homolog of syntenin-1, binds with high affinity to PIP2 via its PDZ domains. Surprisingly, these domains target syntenin-2 to nuclear PIP2 pools, in nuclear speckles and nucleoli. Targeting to these sites is abolished by treatments known to affect these PIP2 pools. Mutational and domain-swapping experiments indicate that high-affinity binding to PIP2 requires both PDZ domains of syntenin-2, but that its first PDZ domain contains the nuclear PIP2 targeting determinants. Depletion of syntenin-2 disrupts the nuclear speckles-PIP2 pattern and affects cell survival and cell division. These findings show that PIP2-PDZ domain interactions can directly contribute to subnuclear assembly processes.
authors.affiliation: Laboratory for Glycobiology and Developmental Genetics, Department of Human Genetics, University of Leuven, Leuven, Belgium.
authors.forename: Eva
authors.initials: E
authors.lastname: Mortier
authors.forename: Gunther
authors.initials: G
authors.lastname: Wuytens
authors.forename: Iris
authors.initials: I
authors.lastname: Leenaerts
authors.forename: Femke
authors.initials: F
authors.lastname: Hannes
authors.forename: Man Y
authors.initials: MY
authors.lastname: Heung
authors.forename: Gisèle
authors.initials: G
authors.lastname: Degeest
authors.forename: Guido
authors.initials: G
authors.lastname: David
authors.forename: Pascale
authors.initials: P
authors.lastname: Zimmermann
mesh_terms: D002352:Carrier Proteins / Q000378:metabolism; D002455:Cell Division / Q000502:physiology; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D002466:Cell Nucleolus / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism*; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008051:Lipid Bilayers / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism*; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D053676:Syntenins; D013997:Time Factors
chemical_list: D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008051:Lipid Bilayers; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D019269:Phosphatidylinositol 4,5-Diphosphate; C109621:SDCBP protein, human; C419574:SDCBP2 protein, human; D053676:Syntenins; C033652:postsynaptic density proteins