title: CCR7/CCL21 migration on fibronectin is mediated by phospholipase Cgamma1 and ERK1/2 in primary T lymphocytes.
abstract: CCR7 binds to its cognate ligand, CCL21, to mediate the migration of circulating naive T lymphocytes to the lymph nodes. T lymphocytes can bind to fibronectin, a constituent of lymph nodes, via their β1 integrins, which is a primary mechanism of T lymphocyte migration; however, the signaling pathways involved are unclear. We report that rapid (within 2 min) and transient phosphorylation of ERK1/2 is required for T cell migration on fibronectin in response to CCL21. Conversely, prevention of ERK1/2 phosphorylation by inhibition of its kinase, MAPK/MEK, prevented T lymphocyte migration. Previous studies have suggested that phospholipase Cγ1 (PLCγ1) can mediate phosphorylation of ERK1/2, which is required for β1 integrin activation. Paradoxically, we found that inhibition of PLCγ1 phosphorylation by the general PLC inhibitor U73122 was associated with a delayed and reduced phosphorylation of ERK1/2 and reduced migration of T lymphocytes on fibronectin. To further characterize the relationship between ERK1/2 and PLCγ1, we reduced PLCγ1 levels by 85% using shRNA and observed a reduced phosphorylation of ERK1/2 and a significant loss of CCR7-mediated migration of T lymphocytes on fibronectin. In addition, we found that inhibition of ERK1/2 phosphorylation by U0126 resulted in a decreased phosphorylation of PLCγ1, suggesting a feedback loop between ERK1/2 and PLCγ1. Overall, these results suggest that the CCR7 signaling pathway leading to T lymphocyte migration on fibronectin is a β1 integrin-dependent pathway involving transient ERK1/2 phosphorylation, which is modulated by PLCγ1.
authors.affiliation: Department of Microbiology, Molecular Genetics, and Immunology, The University of Kansas Medical Center, Kansas City, Kansas 66160, USA.
authors.forename: Laura A
authors.initials: LA
authors.lastname: Shannon
authors.forename: Psachal A
authors.initials: PA
authors.lastname: Calloway
authors.forename: T Paul
authors.initials: TP
authors.lastname: Welch
authors.forename: Charlotte M
authors.initials: CM
authors.lastname: Vines
mesh_terms: D000818:Animals; D002465:Cell Movement; D054421:Chemokine CCL21 / Q000378:metabolism*; D018925:Chemokines / Q000378:metabolism; D002633:Chemotaxis; D005353:Fibronectins / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D019012:Integrin beta1 / Q000378:metabolism; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D051966:Phospholipase C gamma / Q000378:metabolism*; D010766:Phosphorylation; D054400:Receptors, CCR7 / Q000378:metabolism*; D013601:T-Lymphocytes / Q000166:cytology* / Q000378:metabolism
chemical_list: C515478:CCL21 protein, human; C515370:CCR7 protein, human; D054421:Chemokine CCL21; D018925:Chemokines; D005353:Fibronectins; D019012:Integrin beta1; D054400:Receptors, CCR7; C535150:MAPK1 protein, human; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D051966:Phospholipase C gamma