Microtubule organisation and role of LL5-beta in lymphoid stromal fibroblasts (360G-Wellcome-207089_Z_17_Z)

The lymph node is a meeting point for lymphocytes with antigen-presenting cells, and rapidly expands during immune responses. Lymph node structure is highly compartmentalised, and the complex internal architecture is maintained during lymph node expansion. Therefore, mechanisms must exist to balance lymph node integrity with the need to remodel very rapidly. Fibroblastic reticular cells (FRCs) are the most abundant lymphoid stromal cell population, and span the full volume of the tissue. They provide structural support and are highly contractile. FRCs ensheathes bundles of extracellular matrix, termed the conduit, which filters draining lymph. The Acton lab works to understand how lymph nodes are remodeled during expansion and has shown that interaction between FRCs and dendritic cells change FRC behaviour. This project asks how the microtubule networks within FRCs are reorganised as the FRC network expands. Phosphoproteomic screening has revealed that LL5-beta, a protein targetting microtubules to adhesion sites is regulated by interactions between FRCs and dendritic cells. This may provide a mechanism by which FRCs uncouple from underlying matrix, and target secretion of proteases or new matrix to the expanding network. This project will investigate whether LL5-beta coordinates organization of microtubules in FRCs and whether dendritic cell contact changes LL5-beta activity.