Activated PLC-γ1 is catalytically induced at LAT but activated PLC-γ1 is localized at both LAT- and TCR-containing complexes

• Published in: Cellular signalling 2014-04, Vol.26 (4), p.797-805
• Main Authors: Cruz-Orcutt, Noemi, Vacaflores, Aldo, Connolly, Sean F., Bunnell, Stephen C., Houtman, Jon C.D.
• Format: Article
• Language: English
• Subjects: Adaptor Proteins, Signal Transducing - metabolism; Grb2; GRB2 Adaptor Protein - metabolism; Humans; Jurkat Cells; Kinetics; LAT; Membrane Proteins - metabolism; Phospholipase C gamma - metabolism; Phosphorylation; Phosphorylation kinetics; PLC-γ1; Protein Binding; Receptors, Antigen, T-Cell - metabolism; Signal Transduction; T-Lymphocytes - immunology; T-Lymphocytes - metabolism; TCR
• ISSN: 0898-6568; 1873-3913
• DOI: 10.1016/j.cellsig.2013.12.022

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. •Timing of the initiation of LAT Y132 and PLC-γ phosphorylation is similar.•The phosphorylation kinetics of PLC-γ1 rapidly diverge from LAT Y132.•PLC-γ1 forms transient interaction with LAT compared to Grb2.•Activated PLC-γ is localized at both TCR and LAT microclusters.