title: Inositol 1,3,4,5-tetrakisphosphate negatively regulates phosphatidylinositol-3,4,5- trisphosphate signaling in neutrophils.
abstract: Many neutrophil functions are regulated by phosphatidylinositol-3,4,5-trisphosphate (PtdIns(3,4,5)P3) that mediates protein membrane translocation via binding to pleckstrin homolog (PH) domains within target proteins. Here we show that inositol 1,3,4,5-tetrakisphosphate (Ins(1,3,4,5)P4), a cytosolic small molecule, bound the same PH domain of target proteins and competed for binding to PtdIns(3,4,5)P3. In neutrophils, chemoattractant stimulation triggered rapid elevation in Ins(1,3,4,5)P4 concentration. Depletion of Ins(1,3,4,5)P4 by deleting the gene encoding InsP3KB, which converts Ins(1,4,5)P3 to Ins(1,3,4,5)P4, enhanced membrane translocation of the PtdIns(3,4,5)P3-specific PH domain. This led to enhanced sensitivity to chemoattractant stimulation, elevated superoxide production, and enhanced neutrophil recruitment to inflamed peritoneal cavity. On the contrary, augmentation of intracellular Ins(1,3,4,5)P4 concentration blocked PH domain-mediated membrane translocation of target proteins and dramatically decreased the sensitivity of neutrophils to chemoattractant stimulation. These findings establish a role for Ins(1,3,4,5)P4 in cellular signal transduction pathways and provide another mechanism for modulating PtdIns(3,4,5)P3 signaling in neutrophils.
authors.affiliation: Department of Pathology, Harvard Medical School, Dana-Farber/Harvard Cancer Center, Department of Lab Medicine, Children's Hospital Boston, Karp Family Research Building, Room 10214, Boston, MA 02115, USA.
authors.forename: Yonghui
authors.initials: Y
authors.lastname: Jia
authors.forename: Kulandayan K
authors.initials: KK
authors.lastname: Subramanian
authors.forename: Christophe
authors.initials: C
authors.lastname: Erneux
authors.forename: Valerie
authors.initials: V
authors.lastname: Pouillon
authors.forename: Hidenori
authors.initials: H
authors.lastname: Hattori
authors.forename: Hakryul
authors.initials: H
authors.lastname: Jo
authors.forename: Jian
authors.initials: J
authors.lastname: You
authors.forename: Daocheng
authors.initials: D
authors.lastname: Zhu
authors.forename: Stephane
authors.initials: S
authors.lastname: Schurmans
authors.forename: Hongbo R
authors.initials: HR
authors.lastname: Luo
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid; D006801:Humans; D047468:Immunoprecipitation; D007295:Inositol Phosphates / Q000378:metabolism*; D051379:Mice; D009504:Neutrophils / Q000276:immunology* / Q000378:metabolism*; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism*; D021381:Protein Transport / Q000276:immunology; D015398:Signal Transduction / Q000276:immunology*