title: Regulation of NGF-driven neurite outgrowth by Ins(1,4,5)P3 kinase is specifically associated with the two isoenzymes Itpka and Itpkb in a model of PC12 cells.
abstract: Four inositol phosphate kinases catalyze phosphorylation of the second messenger inositol 1,4,5-trisphosphate [Ins(1,4,5)P3 ] to inositol 1,3,4,5-tetrakisphosphate [Ins(1,3,4,5)P4 ]: these enzymes comprise three isoenzymes of inositol 1,4,5-trisphosphate 3-kinase (Itpk), referred to as Itpka, Itpkb and Itpkc, and the inositol polyphosphate multikinase (IPMK). The four enzymes that act on Ins(1,4,5)P3 are all expressed in rat pheochromocytoma PC12 cells, a model that is used to study neurite outgrowth induced by nerve growth factor (NGF). We compared the effect of over-expression of the four GFP-tagged kinases on NGF-induced neurite outgrowth. Our data show that over-expression of the Itpka and Itpkb isoforms inhibits NGF-induced neurite outgrowth, but over-expression of Itpkc and IPMK does not. Surprisingly, over-expression of the N-terminal F-actin binding domain of Itpka, which lacks catalytic activity, was as effective at inhibiting neurite outgrowth as the full-length enzyme. Neurite length was also significantly decreased in cells over-expressing Itpka and Itpkb but not Itpkc or IPMK. This result did not depend on the over-expression level of any of the kinases. PC12 cells over-expressing GFP-tagged kinase-dead mutants Itpka/b have shorter neurites than GFP control cells. The decrease in neurite length was never as pronounced as observed with wild-type GFP-tagged Itpka/b. Finally, the percentage of neurite-bearing cells was increased in cells over-expressing the membranous type I Ins(1,4,5)P3 5-phosphatase. We conclude that Itpka and Itpkb inhibit neurite outgrowth through both F-actin binding and localized Ins(1,4,5)P3 3-kinase activity. Itpkc and IPMK do not influence neurite outgrowth or neurite length in this model.
authors.affiliation: Interdisciplinary Research Institute, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Sandra
authors.initials: S
authors.lastname: Koenig
authors.affiliation: Interdisciplinary Research Institute, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Colette
authors.initials: C
authors.lastname: Moreau
authors.affiliation: Unité de Chronobiologie Théorique, Faculté des Sciences, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Geneviève
authors.initials: G
authors.lastname: Dupont
authors.affiliation: Laboratory of Functional Genetics, GIGA Signal Transduction, Université de Liège, Liège, Belgium.
authors.forename: Ariane
authors.initials: A
authors.lastname: Scoumanne
authors.affiliation: Interdisciplinary Research Institute, Université Libre de Bruxelles, Brussels, Belgium.
authors.forename: Christophe
authors.initials: C
authors.lastname: Erneux
mesh_terms: D000199:Actins / Q000737:chemistry; D000818:Animals; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007527:Isoenzymes / Q000502:physiology*; D020932:Nerve Growth Factor / Q000494:pharmacology*; D016501:Neurites / Q000502:physiology*; D016716:PC12 Cells; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000502:physiology*; D051381:Rats
chemical_list: D000199:Actins; D007527:Isoenzymes; D049452:Green Fluorescent Proteins; D020932:Nerve Growth Factor; D017853:Phosphotransferases (Alcohol Group Acceptor); C051038:Inositol 1,4,5-trisphosphate 3-kinase
keywords: inositol 1,3,4,5-tetrakisphosphate; inositol 1,4,5- trisphosphate 5-phosphatase; inositol 1,4,5-trisphosphate; inositol 1,4,5-trisphosphate 3-kinase; inositol polyphosphate multikinase