Alternative NF-κB signaling regulates mTEC differentiation from podoplanin-expressing precursors in the cortico-medullary junction
The thymic epithelium forms specialized niches to enable thymocyte differentiation. While the common epithelial progenitor of medullary and cortical thymic epithelial cells (mTECs and cTECs) is well defined, early stages of mTEC lineage specification have remained elusive. Here, we utilized in vivo targeting of mTECs to resolve their differentiation pathways and to determine whether mTEC progenitors participate in thymocyte education. We found that mTECs descend from a lineage committed, podoplanin (PDPN)-expressing progenitor located at the cortico-medullary junction. PDPN(+) junctional TECs (jTECs) represent a distinct TEC population that builds the thymic medulla, but only partially supp…
Lymphatic Endothelial Cells Control Initiation of Lymph Node Organogenesis
Lymph nodes (LNs) are strategically situated throughout the body at junctures of the blood vascular and lymphatic systems to direct immune responses against antigens draining from peripheral tissues. The current paradigm describes LN development as a programmed process that is governed through the interaction between mesenchymal lymphoid tissue organizer (LTo) cells and hematopoietic lymphoid tissue inducer (LTi) cells. Using cell-type-specific ablation of key molecules involved in lymphoid organogenesis, we found that initiation of LN development is dependent on LTi-cell-mediated activation of lymphatic endothelial cells (LECs) and that engagement of mesenchymal stromal cells is a succeedi…