title: Inositol tetrakisphosphate limits NK cell effector functions by controlling PI3K signaling.
abstract: Natural killer (NK) cells have important functions in cancer immunosurveillance, BM allograft rejection, fighting infections, tissue homeostasis, and reproduction. NK cell-based therapies are promising treatments for blood cancers. Overcoming their currently limited efficacy requires a better understanding of the molecular mechanisms controlling NK cell development and dampening their effector functions. NK cells recognize the loss of self-antigens or up-regulation of stress-induced ligands on pathogen-infected or tumor cells through invariant NK cell receptors (NKRs), and then kill such stressed cells. Two second-messenger pathways downstream of NKRs are required for NK cell maturation and effector responses: PIP(3) generation by PI3K and generation of diacylglycerol and IP(3) by phospholipase-Cγ (PLCγ). In the present study, we identify a novel role for the phosphorylated IP(3) metabolite inositol (1,3,4,5)tetrakisphosphate (IP(4)) in NK cells. IP(4) promotes NK cell terminal differentiation and acquisition of a mature NKR repertoire. However, in mature NK cells, IP(4) limits NKR-induced IFNγ secretion, granule exocytosis, and target-cell killing, in part by inhibiting the PIP(3) effector-kinase Akt. This identifies IP(4) as an important novel regulator of NK cell development and function and expands our understanding of the therapeutically important mechanisms dampening NK cell responses. Our results further suggest that PI3K regulation by soluble IP(4) is a broadly important signaling paradigm.
authors.affiliation: Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA 92037, USA. ksauer@scripps.edu
authors.forename: Karsten
authors.initials: K
authors.lastname: Sauer
authors.forename: Eugene
authors.initials: E
authors.lastname: Park
authors.forename: Sabine
authors.initials: S
authors.lastname: Siegemund
authors.forename: Anthony R
authors.initials: AR
authors.lastname: French
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Wahle
authors.forename: Luise
authors.initials: L
authors.lastname: Sternberg
authors.forename: Stephanie
authors.initials: S
authors.lastname: Rigaud
authors.forename: A Helena
authors.initials: AH
authors.lastname: Jonsson
authors.forename: Wayne M
authors.initials: WM
authors.lastname: Yokoyama
authors.forename: Yina H
authors.initials: YH
authors.lastname: Huang
mesh_terms: D000818:Animals; D007295:Inositol Phosphates / Q000276:immunology* / Q000378:metabolism; D007694:Killer Cells, Natural / Q000276:immunology* / Q000378:metabolism; D008213:Lymphocyte Activation / Q000276:immunology*; D051379:Mice; D018345:Mice, Knockout; D019869:Phosphatidylinositol 3-Kinases / Q000276:immunology* / Q000378:metabolism; D018160:Receptors, Cytoplasmic and Nuclear / Q000276:immunology / Q000378:metabolism; D015398:Signal Transduction / Q000276:immunology*
chemical_list: D007295:Inositol Phosphates; D018160:Receptors, Cytoplasmic and Nuclear; C061107:inositol-1,3,4,5-tetrakisphosphate receptor; C081655:inositol-1,3,4,5-tetrakisphosphate; D019869:Phosphatidylinositol 3-Kinases