ABSTRACT
WNK1, a kinase that controls kidney salt homeostasis, also regulates adhesion and migration in CD4+ T cells. Wnk1 is highly expressed in thymocytes, and since migration is important for thymocyte maturation, we investigated a role for WNK1 in mouse thymocyte development. We find that WNK1 is required for the transition of double negative (DN) thymocytes through the ß-selection checkpoint and subsequent proliferation and differentiation into double positive (DP) thymocytes. Furthermore, we show that WNK1 negatively regulates LFA1-mediated adhesion and positively regulates CXCL12-induced migration in DN thymocytes. Despite this, migration defects of WNK1-deficient thymocytes do not account for the developmental arrest. Instead, we show that in DN thymocytes WNK1 transduces pre-TCR signals via OXSR1 and STK39 kinases, and the SLC12A2 ion co-transporter that are required for post-transcriptional upregulation of MYC and subsequent proliferation and differentiation into DP thymocytes. Thus, a pathway regulating ion homeostasis is a critical regulator of thymocyte development.
Subject(s)
Cell Differentiation/genetics , Proto-Oncogene Proteins c-myc/genetics , Thymocytes/metabolism , Thymus Gland/metabolism , WNK Lysine-Deficient Protein Kinase 1/genetics , Animals , Mice , Proto-Oncogene Proteins c-myc/metabolism , WNK Lysine-Deficient Protein Kinase 1/metabolismSubject(s)
Colitis/drug therapy , T-Lymphocytes/metabolism , Animals , Disease Models, Animal , Female , Humans , Mice , Mice, SCIDABSTRACT
Adhesion and migration of T cells are controlled by chemokines and by adhesion molecules, especially integrins, and have critical roles in the normal physiological function of T lymphocytes. Using an RNA-mediated interference screen, we identified the WNK1 kinase as a regulator of both integrin-mediated adhesion and T cell migration. We found that WNK1 is a negative regulator of integrin-mediated adhesion, whereas it acts as a positive regulator of migration via the kinases OXSR1 and STK39 and the ion co-transporter SLC12A2. WNK1-deficient T cells home less efficiently to lymphoid organs and migrate more slowly through them. Our results reveal that a pathway previously known only to regulate salt homeostasis in the kidney functions to balance T cell adhesion and migration.
