title: Activated PLC-γ1 is catalytically induced at LAT but activated PLC-γ1 is localized at both LAT- and TCR-containing complexes.
abstract: Phospholipase C-γ1 (PLC-γ1) is a key regulator of T cell receptor (TCR)-induced signaling. Activation of the TCR enhances PLC-γ1 enzymatic function, resulting in calcium influx and the activation of PKC family members and RasGRP. The current model is that phosphorylation of LAT tyrosine 132 facilitates the recruitment of PLC-γ1, leading to its activation and function at the LAT complex. In this study, we examined the phosphorylation kinetics of LAT and PLC-γ1 and the cellular localization of activated PLC-γ1. We observed that commencement of the phosphorylation of LAT tyrosine 132 and PLC-γ1 tyrosine 783 occurred simultaneously, supporting the current model. However, once begun, PLC-γ1 activation occurred more rapidly than LAT tyrosine 132. The association of LAT and PLC-γ1 was more transient than the interaction of LAT and Grb2 and a pool of activated PLC-γ1 translocated away from LAT to cellular structures containing the TCR. These studies demonstrate that LAT and PLC-γ1 form transient interactions that catalyze the activation of PLC-γ1, but that activated PLC-γ1 resides in both LAT and TCR clusters. Together, this work highlights that our current model is incomplete and the activation and function of PLC-γ1 in T cells is highly complex.
authors.affiliation: Department of Microbiology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States.
authors.forename: Noemi
authors.initials: N
authors.lastname: Cruz-Orcutt
authors.affiliation: Interdisciplinary Graduate Program in Immunology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States.
authors.forename: Aldo
authors.initials: A
authors.lastname: Vacaflores
authors.affiliation: Interdisciplinary Graduate Program in Immunology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States.
authors.forename: Sean F
authors.initials: SF
authors.lastname: Connolly
authors.affiliation: Program in Immunology, Sackler School of Graduate Biomedical Sciences, Boston, MA 02111, United States; Department of Pathology, Tufts University School of Medicine, Boston, MA 02111, United States.
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Bunnell
authors.affiliation: Department of Microbiology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States; Interdisciplinary Graduate Program in Immunology, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, United States. Electronic address: jon-houtman@uiowa.edu.
authors.forename: Jon C D
authors.initials: JC
authors.lastname: Houtman
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D051380:GRB2 Adaptor Protein / Q000378:metabolism; D006801:Humans; D019169:Jurkat Cells; D007700:Kinetics; D008565:Membrane Proteins / Q000378:metabolism*; D051966:Phospholipase C gamma / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism*; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051380:GRB2 Adaptor Protein; C110810:LAT protein, human; D008565:Membrane Proteins; D011948:Receptors, Antigen, T-Cell; D051966:Phospholipase C gamma
keywords: Grb2; LAT; PLC-γ1; Phosphorylation kinetics; TCR