title: An isoform-specific PDZ-binding motif targets type I PIP5 kinase beta to the uropod and controls polarization of neutrophil-like HL60 cells.
abstract: Type I phosphatidylinositol 4-phosphate 5-kinase (PIP5KI)-beta participates in establishing polarity during leukocyte chemotaxis. Its final 83 amino acids localize PIP5KIbeta to the uropod of chemotaxing neutrophils and T cells, and interact with ezrin-radixin-moesin (ERM) proteins and EBP50 (4.1-ERM-binding phosphoprotein 50), a scaffold protein with 2 PDZ (PSD-95, disc large, ZO-1) domains. The structural motifs at the PIP5KIbeta C terminus that confer signaling specificity are, nonetheless, unknown. We show that the last 4 residues of PIP5KIbeta constitute an atypical PDZ-binding motif, which steers PIP5KIbeta to the uropod by binding to both EBP50 PDZ domains. Molecular modeling and mutagenesis indicated that PDZ-binding motif is necessary for PIP5KIbeta localization and for chemoattractant-induced neutrophil polarization. Polarity in cells that express PIP5KIbeta mutants lacking the PDZ-binding motif was restored by overexpression of PIP5KIbeta, but not of PIP5KIgamma_i2, another isoform that localizes to the neutrophil uropod. Our results identify an isoform-specific PDZ-binding motif in PIP5KIbeta, which confers specificity for PIP5KIbeta signaling at the uropod during leukocyte chemotaxis.
authors.affiliation: Department of Immunology and Oncology, Centro Nacional de Biotecnología/Consejo Superior de Investigaciones Científicas, Darwin 3, Campus de Cantoblanco, Madrid E-28049, Spain.
authors.forename: Santos
authors.initials: S
authors.lastname: Mañes
authors.forename: Gloria
authors.initials: G
authors.lastname: Fuentes
authors.forename: Rosa M
authors.initials: RM
authors.lastname: Peregil
authors.forename: Ana M
authors.initials: AM
authors.lastname: Rojas
authors.forename: Rosa Ana
authors.initials: RA
authors.lastname: Lacalle
mesh_terms: D020816:Amino Acid Motifs / Q000235:genetics / Q000502:physiology; D002465:Cell Movement / Q000235:genetics / Q000502:physiology; D016764:Cell Polarity / Q000235:genetics / Q000502:physiology; D002633:Chemotaxis / Q000235:genetics / Q000502:physiology; D018922:HL-60 Cells; D006801:Humans; D009504:Neutrophils / Q000166:cytology / Q000378:metabolism; D054731:PDZ Domains / Q000235:genetics / Q000502:physiology; D010750:Phosphoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017923:Sodium-Hydrogen Exchangers / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D010750:Phosphoproteins; D017923:Sodium-Hydrogen Exchangers; C093376:sodium-hydrogen exchanger regulatory factor; D017853:Phosphotransferases (Alcohol Group Acceptor); C020077:1-phosphatidylinositol-4-phosphate 5-kinase