Abstract
Directional cell movement in response to external chemical gradients requires establishment of front-rear asymmetry, which distinguishes an up-gradient protrusive leading edge, where Rac-induced F-actin polymerization takes place, and a down-gradient retractile tail (uropod in leukocytes), where RhoA-mediated actomyosin contraction occurs. The signals that govern this spatial and functional asymmetry are not entirely understood. We show that the human type I phosphatidylinositol 4-phosphate 5-kinase isoform beta (PIPKIbeta) has a role in organizing signaling at the cell rear. We found that PIPKIbeta polarized at the uropod of neutrophil-differentiated HL60 cells. PIPKIbeta localization was independent of its lipid kinase activity, but required the 83 C-terminal amino acids, which are not homologous to other PIPKI isoforms. The PIPKIbeta C terminus interacted with EBP50 (4.1-ezrin-radixin-moesin (ERM)-binding phosphoprotein 50), which enabled further interactions with ERM proteins and the Rho-GDP dissociation inhibitor (RhoGDI). Knockdown of PIPKIbeta with siRNA inhibited cell polarization and impaired cell directionality during dHL60 chemotaxis, suggesting a role for PIPKIbeta in these processes.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Actins / metabolism
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Animals
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Cell Line, Tumor
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Cell Movement / physiology*
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Cell Polarity / physiology*
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Cytoskeleton / metabolism
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Down-Regulation / genetics
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Guanine Nucleotide Dissociation Inhibitors / metabolism
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Humans
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Isoenzymes / chemistry
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Isoenzymes / genetics
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Isoenzymes / metabolism
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Mice
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Neutrophils / enzymology*
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Phosphoproteins / metabolism
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Phosphotransferases (Alcohol Group Acceptor) / chemistry
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Phosphotransferases (Alcohol Group Acceptor) / genetics
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Phosphotransferases (Alcohol Group Acceptor) / metabolism*
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Phosphotransferases (Alcohol Group Acceptor) / physiology*
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Protein Structure, Tertiary / physiology
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RNA, Small Interfering
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Signal Transduction / physiology
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Sodium-Hydrogen Exchangers / metabolism
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rho Guanine Nucleotide Dissociation Inhibitor alpha
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rho-Specific Guanine Nucleotide Dissociation Inhibitors
Substances
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ARHGDIA protein, human
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Actins
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Guanine Nucleotide Dissociation Inhibitors
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Isoenzymes
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Phosphoproteins
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RNA, Small Interfering
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Sodium-Hydrogen Exchangers
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rho Guanine Nucleotide Dissociation Inhibitor alpha
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rho-Specific Guanine Nucleotide Dissociation Inhibitors
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sodium-hydrogen exchanger regulatory factor
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Phosphotransferases (Alcohol Group Acceptor)
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1-phosphatidylinositol-4-phosphate 5-kinase