RT Journal Article T1 Eph/ephrin-B-mediated cell-to-cell interactions govern MTS20+ thymic epithelial cell development A1 Montero Herradon, Sara A1 Garcia-Ceca Hernández, Javier A1 Sánchez del Collado, Beatriz A1 Zapata González, Agustín AB Thymus development is a complex process in which cell-to-cell interactions between thymocytes and thymic epithelial cells (TECs) are essential to allow a proper maturation of both thymic cell components. Although signals that control thymocyte development are well known, mechanisms governing TEC maturation are poorly understood, especially those that regulate the maturation of immature TEC populations during early fetal thymus development. In this study, we show that EphB2-deficient, EphB2LacZ and EphB3-deficient fetal thymuses present a lower number of cells and delayed maturation of DN cell subsets compared to WT values. Moreover, deficits in the production of chemokines, known to be involved in the lymphoid seeding into the thymus, contribute in decreased proportions of intrathymic T cell progenitors (PIRA/B+) in the mutant thymuses from early stages of development. These features correlate with increased proportions of MTS20+ cells but fewer MTS20− cells from E13.5 onward in the deficient thymuses, suggesting a delayed development of the first epithelial cells. In addition, in vitro the lack of thymocytes or the blockade of Eph/ephrin-B-mediated cell-to-cell nteractions between either thymocytes–TECs or TECs–TECs in E13.5 fetal thymic lobes coursed with increased proportions of MTS20+ TECs. This confirms, for the first time, that the presence of CD45+ cells, corresponding at these stages to DN1 and DN2 cells, and Eph/ephrin-B-mediated heterotypic or homotypic cell interactions between thymocytes and TECs, or between TECs and themselves, contribute to the early maturation of MTS20+ TECs. SN 0948-6143 (Print) 1432-119X (Online) YR 2016 FD 2016-08 LK https://hdl.handle.net/20.500.14352/17614 UL https://hdl.handle.net/20.500.14352/17614 LA eng NO Ministerio de Ciencia e Innovación (España) NO Ministerio de Economía y Competitividad (España) NO Ministerio de Sanidad y Consumo (España) DS Docta Complutense RD 29 abr 2025